1. Absolute drivel, it's pseudo-science!
2. Far-fetched, but at least based on observations
3. Can't decide, further research needed
4. It's quite the intriguing idea, which may explain a lot of peculiar human traits
5. It's the greatest scientific discovery since Darwin!
July 12th, 2011, 08:18 AM
I feel the need to enquire about people's general attitude toward the so-called Aquatic Ape Hypothesis, which some are labeling pseudo-science and some a brilliant idea, and which seem to divide both the educated and non-educated quite strongly.
Read about the so-called Aquatic Ape Hypothesis here:
http://en.wikipedia.org/wiki/Aquatic_ape_hypothesis
Refuting website: http://www.aquaticape.org/
Defending website: http://www.riverapes.com/
Don't know if the gradual options are perfect ...
How many threads showing that it's crap do we really need on this?
http://www.thescienceforum.com/Aquat...sis-28828t.php
http://www.thescienceforum.com/Aquat...eory-6404t.php
http://www.thescienceforum.com/Aquatic-ape-11686t.php
Aparently more than one. It's like the theory that won't die.Originally Posted by inow
AAH would be acceptable if presented as additional to the many good explanations which, taken together, show the inevitability of modern humans. Detractors however frame AAH as an exclusive proposition. Then proponents appear foolish defending one cause of an adaptation, or indeed the species, as the main cause. Remember your likening this debate to heliocentrism vs. geocentrism?
I can't vote because there's no option for "helps explain".
Hmm ...
You may have a point here, however, the problem is that many of the previous 'good' explanations for why humans differ from the other great apes now seem weak by comparison, if one seeks biological precedence for these unique human traits in question.
Either it's a weakness that AAH opens a floodgate of explanations for human evolution ... or it's a strength. Either AAH is Dan Brown or it's Alfred Wegener. (Or perhaps something in between, which of course then would illustrate your point.)
I will admit, that after a certain ammount of study into this splash-splash notion, one sense a fierce and continuous 'Heureka' sensation, which I'm sure is similar to that which Galileo and Darwin must've felt (and Dan Brown too, I suppose ...).
I'm not sure I understand your analogy. To me it seems that Copernicus' and Galileo's suggestion about the Sun being the center of the near-universe ended up making eg. Tycho Brahe's peculiar attempt to keep Earth at the center utterly redundant.
Utterly. But one thing I learned from the thread on human hairlessness, is that a trait may have multiple causes - indeed the more causes the more advantageous the trait. Even a crapload of petty causes amounts to significant adaptation, with no one cause being crucial. Taking bipedalism for example, we could easily list the pros for that on two hands. That is not the place to raise one finger saying, "This one explains bipedalism." One good theory needn't contradict the others. In my humble opinion AAH is neither contradictory nor revolutionary, notwithstanding its debators' egos.I'm not sure I understand your analogy. To me it seems that Copernicus' and Galileo's suggestion about the Sun being the center of the near-universe ended up making eg. Tycho Brahe's peculiar attempt to keep Earth at the center utterly redundant.
That some populations of our ancestors often foraged shorelines and shallows is quite enough.
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I naturally sympathise with any theory bringing water into the picture, since I grew up with BC Coastal Native culture, spending weeks of summer vacation picking around the rich shoreline. Behaviours described by Morgan are intuitively obvious to modern human children who explore this niche. And I'll hazard to state that opponents of AAH strike me as landlubberly, city-raised, alienated from the element. Just my personal sentiments.
I'm sorry, but I can't help but compare this with that of Alfred Wegener's continental drift (today called plate tectonics). Before this peculiar idea, there were countless suggestions about the cause of earthquakes, vulcanoes, mountains, tsunamis, etc., each with causes independent of each other, and then this German meteorologist suddenly collects them all in one hat with this one idea. With one sweep, the life's work of thousands of geologists were ripe for the trash bin, and it would be folly to suggest that the other ideas could somehow be true alongside it.
And I fear the comparison with AAH goes even deeper, because the field of geology probably reacted the exact same way against Wegener as the field of anthropology did against Hardy and Morgan: First complete ignorance, then fierce ridicule. Which is why it took half a century for geologists to even go look for the evidence to support such a pathetic notion as 'moving land masses'. Evidence, which of course were somewhat easy to find, once people got off their keaster.
You could ask yourself, why in the hell a bleeding weatherman is talking about geology? Or why a feminist hack of a TV screenplay writer is talking about human evolution? But then you can also ask yourself, why in the hell a bleeding lens maker like Galileo is talking about the structure of the universe?
One of the few academic replies to AAH is a 1997 paper by John Langdon called "Umbrella hypotheses and parsimony in human evolution: A critique of the Aquatic Ape Hypothesis." In this he makes the case, that one concept behind complex scientific matters is too much to ask of reality, even though such ideas are easier for the 'rabble' to understand.
Well, sometimes it is not. Sometimes the sun is at the center, sometimes life is a metaphysical tree, sometimes Africa and South America were once attached to one another like giant pieces of a puzzle, sometimes man is not made in the image of God because God does not have an image, and sometimes humans are beach apes.
If there (perish the thought) should be validity to AAH at a scale similar to that of Galileo, Newton, Darwin, Mendeleev, Einstein and Wegener, it would indeed leave the life's work of countless hard working scholars completely worthless. To take all those diverse suggestions as to why this or that peculiar feature exist in modern and past humans, and suggest they are null and void, because this one idea explains close to all of them with severe parsimonal support and without much co-existence to spare for the myriad of other suggestions, that does indeed sound incredibly cruel. Almost as cruel as life as described by Darwin.
Perhaps then it makes sense, why anthropology did not jump directly into this no-brainer concept from day one.
The above has been said many times before by pro-aqua people. So hell with it, I do too.
I agree with much of what you have said, but your use of hyperbole in describing the impact on geologists' life work is grossly overstated. (And that is not hyperbole.)
The impact on the work of most geologists was completely irrelevant. Few geologists deal with (exuce the pun) Earth shattering ideas. The study of a lower Triassic ecology is unaffected by whether or not that ecology is moving over the face of the planet at 2.5 cm a year. The interpretation of the meaning of the study is affected and in that regard the work of many geologists was greatly enhanced.
The objection to Wegner's work lay with the physicists, who saw no mechanism and doubted the ability of solid rock to 'flow'. An honourable exception was Arthur Holmes a physicist turned geologist, who proposed mantle convection as a mechanism as early as 1929.
The same would be true of many if not most anthropologists whose work would simply be reinterpreted in the light of the new paradigm.
It's not the detractors who first present the idea as "exclusive", but the proponents. Others are then forced to examine what the proponents say about their ideas; it doesn't make sense to give the critics any grief because of what the proponents of the idea(s) are doing. I've often said that if all that was being said in the AAT/H was that hominins waded and even swam at times during our evolution, and that this was part of our becoming one of the (if not the) supreme environmental generalists among mammals, it would be entirely uncontroversial. But that's not what they're saying.
And what they say is nonsensical on several levels. Part is that they are essentially saying that we became supreme environmental generalists among mammals by adapting to one environment, rather than more and more different ones as mainstream ideas say. Another is that they make claims about features that are not true since they describe these features very inaccurately. Another is that when they make these comparisons about what other animals share these features (and remember that the features are almost always inaccurately described) they tend to be coy about what other animals these are, but their descriptions only fit fully aquatic mammals -- cetaceans, pinnipeds, and sirenia. Yet the claim is that we underwent convergent evolution (wherein similar features arise which are similar in function) without anything remotely like similar selection pressure.
Add to that that they usually describe others' research inaccurately, alter quotes, and engage in various logical fallacies, and you have a set of ideas that, to put it mildly, don't inspire confidence.
The above is based on my long experience with the arguments presented by all the major proponents of the various forms of the AAT/H (BTW, they often disagree with each other, radically, yet pretend that their various diffierent ideas all bolster each other).
Some recommendations for my site:
"Jim Moore's Aquatic Ape page is the definitive web resource for dissecting this fringe theory" - P.Z. Myers (Pharyngula), U of Minnesota biologist
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"Jim Moore has already done a fantastic job dismantling the various problems with the AAH" -- Brian Switek (Laelaps)
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"For a thorough and entertaining discussion of the theory that we went through an aquatic phase prior to Australopithecus, this is THE place to go. Erudite, witty, and insightful" -- [yet another] Jim Moore, UCSan Diego anthropologist
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"Jim Moore's excellent website" -- John Hawks, U of WisconsinMadison anthropologist
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John Hawks
Posted August 18, 2009 at 3:06 pm | Permalink
I second the recommendation of Jim Moores website:
Aquatic Ape Theory (AAT): Sink or Swim?
Its the equivalent of the talk.origins FAQ for AAT.
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"Southern Fried Science (Blog): by WhySharksMatter, on September 9th, 2010
("David is a graduate student in South Carolina studying shark conservation.")
For an extremely thorough resource devoted to debunking this hypothesis, please see Jim Moores excellent website.
***
Peez (the online name of a professor of biology at a Canadian university)
"Incidentally, I think that anthrosciguy's AAH site rocks, and I have a PhD in evolutionary biology (in case that is important)."
Jim, your References page alone is worth the visit just to bookmark. I've copy/pasted it to a document on my hard drive should your site ever go down (hope you don't mind).
Thanks for popping in here from time to time whenever a new aquatic ape thread crops up. It's always good to have your perspective and experience on the topic.
Thank you for the compliment. (I hope to keep my site going forever, but you never know, and outages do happen after all.)
If the existence of a period of structural adaptation to a more or less amphibious way of life is uncontroversial, then why is it so stridently rejected - and quite dubious, poorly supported alternative explanations for a some features, amplified and repeated - by so many authorities in the public discourse?
As far as I can tell, the most solid objections to the AAT overall (rejecting the whole thing) are to the various personal or intellectual flaws of some of its proponents and their extrapolations. These are undeniable, but there remains the matter of the history of human evolution in fact. To point to one obvious reality, bipedalism remains wholly unexplained by the standard or conventional hypotheses - and some fairly ridiculous or confused notions have received the respect denied the AAT enthusiasts. One would think that the embarrassment of having the much trumpeted bipedal savannah ape hypothesis, (which never made much sense despite its wide spread and continual presentation as established) controverted by the new fossil discoveries, would be a bit humbling, and increase the willingness to take a more serious look at other proposals - especially those whose hypotheses have been supported by new and incoming evidence. But apparently not.
Meanwhile, no doubt various absurdities will be advanced by people in support of the AAT, and will be properly dismissed by superior expertise. Why a similar weeding service is denied the savannah ape theory or the bipedal tree limb walking proposal or the ease of face to face copulation notion or the tool kit transport explanation or the rest of the menagerie of creative whims burdening the discussion of bipedalism, I don't know. But if the aquatic phase hypothesis had come along first, before the savannah story, I doubt that the common suggestions for bipedalism such as "seeing over tall grass" - for example - would be taken seriously today.
Well, I have read through the aquaticape.org site without finding any ad hominem arguments and instead found many scientific arguments. It's almost like you haven't even read it.
This argument seems to have been refuted quite convincingly, as far as I am concerned. The AAT does no better at explaining bipedalism than any other hypothesis.These are undeniable, but there remains the matter of the history of human evolution in fact. To point to one obvious reality, bipedalism remains wholly unexplained by the standard or conventional hypotheses - and some fairly ridiculous or confused notions have received the respect denied the AAT enthusiasts.
Ad hominem arguments are not my reference - although plenty are to be had, in the arena, I am not talking about them.I did read it, years ago and just now to check my memory. I am not as persuaded as you by some of the "scientific arguments" (some, like the observations on hairlessness not being an aquatic adaptation, seem well taken).
Since it has come up in particular, this one will do as illustrationIt could hardly do worse. If we are content with silence on the topic, OK. Otherwise, let's consider the better of even a bad lot of proposals - consider it fairly, and not in its weakest descriptions.
And in that light I see no refutation, actually - some complaint about the details of one person's, Elaine Morgan's, Just So Story layout, but nothing to refute the essential observation that the wading ape is the only explanation advanced so far that puts a quadrupedal, tool less, tree adapted ape on the ground and on its hind legs for the necessary hours on end, and gives it the necessary advantage over disadvantage suffered. As in a couple of other places, that site seems to miss the point here: we read, for example, that the blood pressure effects and salt retention and so forth do not kick in until an hour or more after entry into the water, and therefore cannot be advanced as evidence of cost avoidance. But getting the poorly designed ape into the bipedal environment for long times (more than an hour) and extensive, continual employment of a bipedal gait, is exactly the problem we face - and the AAT handles.
Likewise we read that humans were brachiating like gibbons, not knuckle walking like chimps, before bipedalism, and brachiaters walk on their hind legs when forced to the ground - but that begs the question: the whole point is to figure out why they didn't become knucklewalkers or baboon style plantigrads, as all other apes taking to the ground did (and every other tree dweller taking to the ground has done).
And so forth.
Yes you were. You said that arguments against the AAT were based on the personal or intellectual flaws of the proponents.
The solid ones, I said, yes - "and their extrapolations" of the basic setup, to the hypothesis overall - the whole thing.
That's the form of the arguments put forward in this thread, by the guy you are linking, in his first post on page one, for example. He has a lot of trouble with - - - I'll just quote it:See? That's fairly typical of the good ones - the objections based on reason and consideration.I've often said that if all that was being said in the AAT/H was that hominins waded and even swam at times during our evolution, and that this was part of our becoming one of the (if not the) supreme environmental generalists among mammals, it would be entirely uncontroversial. But that's not what they're saying.
And what they say is nonsensical on several levels. Part is that they are essentially saying that we became supreme environmental generalists among mammals by adapting to one environment, rather than more and more different ones as mainstream ideas say. Another is that they make claims about features that are not true since they describe these features very inaccurately. Another is that when they make these comparisons about what other animals share these features (and remember that the features are almost always inaccurately described) they tend to be coy about what other animals these are, but their descriptions only fit fully aquatic mammals -- cetaceans, pinnipeds, and sirenia. Yet the claim is that we underwent convergent evolution (wherein similar features arise which are similar in function) without anything remotely like similar selection pressure.
Add to that that they usually describe others' research inaccurately, alter quotes, and engage in various logical fallacies, and you have a set of ideas that, to put it mildly, don't inspire confidence.
What I said above is not what you said. Do you not see that? There's a vast difference between ocassionally wading, swimming, and/or eating foods found in or near water and "a period of structural adaptation to a more or less amphibious way of life".If the existence of a period of structural adaptation to a more or less amphibious way of life is uncontroversial, then why is it so stridently rejected - and quite dubious, poorly supported alternative explanations for a some features, amplified and repeated - by so many authorities in the public discourse?
The various forms of the aquatic idea would still face the problem of not matching facts, no matter when if they had been presented earlier or later. Some of your other posts' wording seems like you're saying that the idea should be considered outside of what has been presented as the idea by the proponents of the idea. This of course cannot be done.
There are a number of things that no doubt helped provide selection for effective bipedalism, and the top of the list for these would be food-getting/foraging, which is by far, in every study, the activity most often correlated with bipedalism in our close relatives the African apes. Observation and displays would also be on that list, but well down, as would wading and other activities.
My own criticisms speak about "personal flaws" of proponents only insofar as they are revealed by their doing things like alter quotes, misunderstand evolutionary theory, misrepresent what researchers have said, etc. I think it's reasonable to object to their doing that, especially when you see it's an ongoing, consistent habit (or perhaps tactic would be a better descriptor). This is not an ad hominem; the problem is not "they have personal flaws so they're wrong", it's more like "they're making mistake after mistake and even things that look like deliberate distortion and therefore they're wrong".
One other point I forgot to mention is that some researchers over the years (for instance Russell Tuttle, as well as my late wife Nancy Tanner) have suggested that the evidence shows that our ancestors, the last common ancestor we share with the African apes, were likely already bipedal (in not quite the same way we are, but a habitually bipedal mammal). With the results of study of the "Ardi" fossils as published earlier this year (or last?), showing this extremely early hominid to have used fully upright bipedalism, this view seems to be the correct one. This also puts a big hole in most forms of the AAT/H, in particular the one done by Hardy and by Morgan and those which closely follow it in terms of bipedalism and the idea of wading and/or swimming as instrumental in the inception of bipedalism.
Last edited by anthrosciguy; October 18th, 2011 at 03:58 PM.
Hi Jim, good to see you here!
First: When you talk about humans as "supreme environmental generalists", I think it's a fair characterization of our species, and indeed that's how most paleoanthropologists today describe our ancestors -- even Carsten Niemitz's pro-AAH theory is named "Amphibian Generalist Theory" and assumes a generalist starting point in hominid evolution.
But before we accept this notion, I have some doubts -- What's actually meant by being a "super generalist"? How, and why, did we become so, what would be the selective pressure(s) that led our ancestors into this successful but unprecedented evolution pathway? Any similar case in the biological world?
In this regard, I would rather think humans as "multi-specialists". In particular, we are specialized in multiple ways --
(1) climbing (vestigial of brachiating),
(2) swimming and diving (our ability is within the range of semi-aquatic mammals),
(3) bipedal walking and running (not for speed but for endurance),
In contrast, we are not specialized in other ways e.g. sprinting, burrowing, gliding, flying, underwater living...
Thinking in this way, we can reason every set of specialization requires its own conditions, mechanism and time-frame, not just "we are adapted to multiple niches" that lacks any detail.
Second: It seems your major complaints on the methodology of AAH come from the layman side -- popular writings of Elaine Morgan, forum posts by layman adherents (like Marc, Algis, me), and many of the general public that superficially attracted to the idea. But if we bother to find, there are serious researches and writings from the academics, to name a few:
- Alister Hardy's original essays (educated guess),
- Compilation of papers like "Human Brain Evolution: The Influence of Freshwater and Marine Food Resources",
- A whole issue of Quaternary International volume 239 dedicated to shell midden research,
- Various works by specialists like Stephen Cunnane, Kathy Stewart, Jose Joordens, Jon Erlandson, Carsten Niemitz, ...
Reasonably, those "personal flaws" you accused of laymen writers should be minimum in them. Is it possible to, for the purpose of scientific evaluation, ignore those layman writings, and consider only the academic works, verify their validity and plausibility, see whether they support Hardy's original proposal or not? Will it do a better justice to those researchers, and to the idea itself?
Chak
Last edited by chakazul; August 2nd, 2011 at 11:36 AM.
Chak, please stop pretending that you haven't read the answers to your questions before here or on other forums. You've done this now several times; it doesn't become you and makes you look deliberately dishonest (and it's ludicrous to place yourself in the ranks of the major proponents of the AAT/H -- really, get a grip). In fact, as you know, I have dealt at some length with Hardy's claims, with Cunnane and the rest of the omega-3 boosters, and so on, and even have pages on my website dealing with a great deal of that. (Hardy. Cunnane and Crawford, etc.) It is also ludicrious to suggest that it is inappropriate to critique the people who have done, by far, the greatest amount of writing and claims-making regarding the AAT/H, no matter their academic status. And, sadly, your notion that these other proponents exhibit fewer errors about basic facts and evolutionary theory is not so, as I have shown and which you well know by now.
Last edited by anthrosciguy; August 2nd, 2011 at 06:22 PM.
Jim, calling me dishonest or something doesn't let you evade from my questions.
I have read your pages about Hardy and Cunnane et al. Dispite me being far from convinced (because of various errors, like claiming that training alone can make people do anything, or mixed up "tool-making" and "tool-using, etc), more importanly, I didn't see any of the "personal flaws" you mentioned shown up in their reasonings.
For example, if someone proposes that a watered environment or a shore-based diet is a major force in evolution, is it methodologically very different from those who advocated savannah-dwelling as a major force, or meat-eating as the determinant of brain expension? If the former ones are "environmental / dietary deteministic" and "don't understand evolutionary forces", and so do the later ones? I think they're better said as merely schools of thoughts like other evolutionary ideas.
My concern is, you tend to characterize most, if not all, people adhered to AAH as deliberately dishonest, misinterpleting information, and misunderstanding evolution... Maybe some layman works do fit in this description, but this is especially insulting and offending to scientists and their research results, and in fact a serious accusation. Considering Kathy Stewart, Jose Joordens, Jon Erlandson, Carsten Niemitz, Anna Gislén, Erika Schagatay... etc, what do you say about their honesty and knowledge?
BTW, you didn't explain what's meant by a "supreme generalist".
Last edited by chakazul; August 3rd, 2011 at 08:51 AM.
Does anybody have any information on the supposed diet of an aquatic ape living on the seashore? A detailed analysis? It occurs to me that the vast majority of suitable foods available in such an environment would be most easily found along rocky shores or mangrove swamps exposed by the receding tide. Molluscs, crustaceans, echinoderms and trapped fish could all be foraged for quite easily and consumed without ever having to get more than a big toe wet. Similarly, on a sandy shore a diet would be restricted largely to digging at low tide for animals burrowed beneath the sands. I can't understand where the need arises for this aquatic-ape-thing to be frolicking around in the highly dangerous waters of the ocean for extensive periods of time. Help...
There are a couple problems with the diet claims, which have become a biggish part of the core claims of support for the AAT/H (some of it critiqued on my website here). One is the dietary determinism involved, the other is that the proponents end up essentially saying our brains couldn't develop normally without shoreside foods even though we know that many populations of people for many many generations in prehistory and later did without those foods and developed normal brains, and then there's the measurements of dietary requirements and the fact that although some parts of our requirements are easier to come by at seashores, others are not.
And the biggest problem with those claims is what you point out: even if they were using those foods and even if every hominin when we got larger brains (say, during Homo) ate those foods (and this is not so) then it still wouldn't mean they had to do much, if any, swimming or diving to get them. And the base claim of the various versions of the AAT/H is not simply that some of us lived near water and used some water-based resources, because that is a given and is not at all controversial. Their claim is that a number of characteristics -- just which ones differs from one proponent to the next -- arose as a result of this and that these characteristics are similar to those found in some animal or animals which live near or in water. That raises two other problems: first that they describe these characteristics wrong and their idea suffers from GIGO; the second that the beasts which match their claims, the beasts they are saying we were convergent with in these features, are cetaceans, pinnipeds, and sirenia -- all fully aquatic mammals which have been fully aquatic and highly specialized for that life for tens of millions of years. This is far longer than hominins of any sort have existed and had one hell of a lot more selection pressure than any of the major AAT/H proponents say happened.
But a lot of wading and swimming and diving would have come in mighty handy - direct selection pressure (immediate food reward) for incremental bipedal capability, incremental extra fat, incremental breath control, fine motor control and thumb coordination, crude tool employment, larger brain (varied, patchy, and seasonal supplies of very good food), etc.
Arguing against the weakest and most exaggerated AAT hypotheses is a waste. The stronger argument would be that even if not demonstratedly necessary, many developments in human physiology (and behavior, no?) do make sense as bottleneck adaptations to an amphibious niche. And they don't make nearly as much likely sense in the other hypotheses advanced so far. The foolishness conventionally accepted as argument for the savannah hypothesis, for example, deserves less credit than even the flake schools of AAT.
Criticizing the proponents as a group, the flaky in with the sensible, for inconsistency and various foolishness, does not handle the hypothesis.
That's wrong. What the Ardi and other early fossils display supports bipedalism as an early adaptation - before tool use, savannah habitation, or any of the other common proposals for bipedal locomotion (they didn't make much sense anyway, now they don't even match the timeline). The aquatic niche adaptation is just about the only proposal on the table that does fit the new timeline - another point in its favor, along with explaining incremental transitional forms and so forth.
Last edited by iceaura; August 4th, 2011 at 02:01 AM.
Note that there were never an "aquatic ape", not even the AAH says so. Instead "amphibious" is the proper word.
If you're talking about the consumption of aquatic food by humans and our ancestors, there're plenty of information around, like Wikipedia:Omega-3 fatty acid or pop-sci books like "Survival of the Fattest". For more academic stuffs, see this compilation of papers and this journal issue.
The basic idea is, according to archaeological findings, our ancestors consumed freshwater foods like catfish and molluscs, and later exploited marine seafood like oysters, fish and marine mammals. These foods sources are relatively rich in omega-3 like DHA and AA, also micro-nutrients like iodine, iron, zinc and selenium, all are essential to the maintenance of our extravagant brain and our fragile mental health. This aquatic diet was possibly one of the major factors (along with tool-making and hunting) that allow us to evolve much larger brains than our primate fellows. (Despite Jim's "dietary determinism" claim, there's never ignorance of other factors).
Don't be too worried about the "highly dangerous waters" -- the happy amphibious life of the coastal peoples today proves that there's no problem to live, feed, breed, swim, dive, and feel at home in the oceans. They even have a very good underwater vision.
I don't think the dietary aspect is "the weakest and most exaggerated" one, instead it is by far the strongest claim among the AAH-related ideas. It is the most scientifically studied and verified, and is relatively well accepted (though still debated) among the mainstream scientific community.Arguing against the weakest and most exaggerated AAT hypotheses is a waste. The stronger argument would be that even if not demonstratedly necessary, many developments in human physiology (and behavior, no?) do make sense as bottleneck adaptations to an amphibious niche. And they don't make nearly as much likely sense in the other hypotheses advanced so far. The foolishness conventionally accepted as argument for the savannah hypothesis, for example, deserves less credit than even the flake schools of AAT.
We call this creating a "straw man": that all pro-AAH people should be thinking the same weird idea, and any diversity or evolution of ideas is not recognized -- they're said to be dishonest and inconsistent.
Elaine Morgan was criticized as making straw man arguments against the Savannah model, but now some of her criticizers were making the same mistake. I think this is a widespread logical fallacy.
No one has ever demonstrated that wading had any influence on any feature expressed by extant humans, or any human ancestor.
Also, wading "fits the new timeline" only in that wading can be proposed at any point along the time line, or throughout the time line if you wish. But without any evidence of causation between wading and the features in question, the proposition carries no weight.
Strikes me that the most likely food eaten by a biped with excellent arms living by the sea would be anything that can be made available by smashing it between two rocks. That is : shellfish, barnacles, sea urchins etc. Most of these are available at low tide, and only a limited amount of wading would be required. The big advantage to humans or pre humans is the excellent use of two hands and rocks to do the smashing.
The large brain is not dependent on diet. It is an artifact of evolution. The elephant has one of the largest brains in nature, and it is a herbivore that eats grass and leaves. The elephant is sufficiently intelligent that it is one of the few animals to have passed the mirror test.
I still think that an aquatic ape would have left lots of fossils in marine sediments, and this has not happened. Fossil evidence for the aquatic ape hypothesis is zero.
Again, that is such a bizarre exclamation, when AAH-proponents has done nothing but that. There wouldn't be an aquatic ape hypothesis without such demonstrations. Human nakedness is demonstrated to be a general trend for aquatics and semi-aquatics (especially in tropical zones). Human bipedality is demonstrated to be a general trend for primates as a subfamily, when moving through water. The need of various nutrients for a healthy development of eg. the human brain is demonstrated as more readily found in aquatic foods. That human infants swims with a high degree of ease before they can walk is an aquatic demonstration. That water birth drastically limits the need for episiotomy is an aquatic demonstration. That humans communicate via conscious verbal speech is an aquatic demonstration, seeing the only known other example in cetaceans. That human behavior leaves it to be drawn to sand-covered coastal regions in especially tropical zones is an aquatic demonstration. That Homo Sapiens migrated out of Africa along the Southern coasts of Asia and ended up in Australia long before China and Europe is an aquatic demonstration. That humans are instrinsically capable of this William Trubridge 101m CNF World Record Freedive - YouTube , is an aquatic demonstration.
Trying to rule out any 'straw-man' perspective on AAH-opponents, they do tend to share a few key elements, which to me leave them severely weakened in this debate:
One, they seem reluctant to read the actual source texts to eg. Westenhöfer, Hardy and Morgan, but rather prefer this hypothesis be about some sort of ocean-primate, because that version is easy to declare folly. The occasional bong-head with a website going 'wow, we descend from dolphins, awesome' notwithstanding, no serious AAH-proponent has ever suggested more than a beach-ape, a coastal primate with a habitat similar to that of a hippopotamus. The general consensus seems to be that this idea has to be crazy.
Two, they constantly yell and wail that there's no empirical evidence for this or that AAH-argument, but voluntarily ignore that the exact same mind gap is also the case with any land-based argument. In this mind gap, we can only lean on the principle of parsimony.
And thus three, they grossly mal-apply the principle of parsimony, seemingly ignoring that many AAH-arguments have biological precedence, whereas many land-based suggestions fail to strengthen its case in a similar way. Saying that AAH is not supported by Occam's Razor is akin to claim that a car with four wheels does not have four wheels.
To be fair, I imagine that many AAH-proponents also ignore to read source texts of AAH-opponents, but as an avid reader of Jim Moore's aquaticape.org (about once a year in full, it is indeed the best representation of con-AAH observations), I do make an effort to ignore this 'hunch' of mine that AAH is spot on and be open for any potential Dan Browninitis. Basically, I hate to be wrong. And yet, the site never convinces me that I'm on the wrong track, actually every time I find countless examples of the above misrepresentations. I find countless misquotations and focus on AAH-observations decades old and later retracted.
I've come not to blame Jim Moore for anything (have to admit, I haven't always done that). If this is all a wild goose chase and comparable with Erich von Däniken, he is an admirable proponent for 'keeping it real', which I can use his website for.
That depends on the interpretation of the existing fossil archive. Note that most proto-human fossils actually are found in lake sediments. Granted, that doesn't mean that all members of the said species lived lake-side, as the probability of conservation increases in water sediments. Preserved specimens may be over-represented, as specimens who died inland may just not have been preserved. But it could be interesting to see the percentage rate of the suggested proto-human fossils that were conserved in aquatic sediments.
Unfortunately, ammount of fur on a past primate (which would be a strong indicator for an aquatic point in time) cannot be confirmed on ancient fossils (unless we find archeopteryx-like human fossils one day, which is not bloody likely), but bipedalism can be confirmed to at least Ardipithecus, and potentially twice as old as that. The find of Ardipithecus may confirm an aquatic ape suspicion, which is a potential relationship between the homo lineage and the semi-aquatic ape Oreopithecus. Hear me out.
I have been very doubtful as to such a connection, but I find it very intriguing that Oreop. (9-7mya) and Ardip. (4.4mya) share a very similar grabbing 'thumb-like' big toe, which seems to have disappeared in the australopithecines (3.6-2.4mya) and homo (2.4-0mya). This also makes it interesting to reconsider the European Dryopithecus (12-9mya) as an ancestor to both Gorilla, Pan (chimp, bonobo) and Homo. Both because Oreop., which lived on a Mediterrenean archipelago including current Sardinia and Toscany, have the same big-toe, but also because pelvic studies suggest it was bipedal, as was Ardip. and later Australopithecines and Homo. On top of that, the charcoal layers in which Orepop. has been found (in large numbers, even) illustrate that it lived in wetlands (it has been dubbed 'the swamp ape'), which makes it interesting to consider as perhaps the first 'aquatic ape' of human evolution.Something that further supports this relationship, is that both Oreop. and its potential ancestor Dryop. have the iconic eyebrow bones, which all suggested human ancestors from Ardip. and all the way to Homo Sapiens Neanderthalensis have, and which Gorilla and Pan also have till this day, but which great apes in Africa simultaneous with Dryop. and Oreop. is missing.
In such a scenario, human evolution (and the aquatic ape) would be as follows: A descendant of Proconsul, Dryopithecus, migrates out of Africa ca. 12mya in a warm period with tropical jungle expanding far into Eurasia. Some Dryop. evolve into modern Orangutan in East Asia, others evolve in Southern Europe and develop eg. the high eyebrow bone. As colder climate sets in, the tropical jungle moves southward again and three descendants to the European Dryop. (Gorilla, Pan and Homo), evolve three-way and migrate back into Africa (possibly along the Iberian, this Mediterrenean archipelago and the Levant, one lineage each way). Two (Gorilla, Pan) stay in the jungles to this day, whereas the third (Homo) via the Mediterrenean archipelago evolve into a coastal form with Orepithecus, which then later evolve into Ardip., Australop. and Homo.
In this scenario, humans have been aquatic apes for nine million years, with Orepithecus being the first non-common ancestor for humans and chimps, but only to humans. The requested evolutionary force for change is the dwindling jungle in Southern Europe after the end of the warmer period, when a group of Dryop. in the mid-Mediterranean was forced to adapt to an archipelago or go extinct.
There are three problems with an Oreopithecus link, though (and plenty other, I'm sure).
1) Geographical:
For Gorilla, Pan and Homo to have migrated from Southern Europe back into Africa in the suggested time-frame would suggest a migration of Homo through the Sahara region. Today, this is the largest desert in the world, almost totally bereft of life and not very likely for an aquatic ape migration into East Africa. One could counter-argue, that Sahara has not always been a dry void, as even in historic times, rock paintings from human cultures show elephants, giraffes, etc. in the middle of a now dry desert. It could be interesting to determine the paleogeograpical characteristics of the Saharan region in the suggested time frame (circa 7mya), in view of this potential ape migration. If Sahara was indeed lush, green and perhaps wet in late miocene, one might find proto-human fossils along old river beds and lake shores with exposed layers from the suggested time frame.
In this context, the species Sahelanthropus (7mya, the 'Toumaļ' fossil) becomes interesting, being found in Tchad out in Sahara on a then lake shore. Then Sahel. might be a link between Oreop. and Ardip., also because Sahel. has the high eye brow bone. (Unfortunately, Sahel. was found with only scull fragments, so nothing can be concluded about potential bipedalism via the pelvis.)
2) Political-social:
Considering a Southern European spawn of humanity would probably be a big camel to swallow for the academic community, considering the 19th century fight to get arrogant European scientists to even consider that humanity came from outside their own continent (another milestone by mr. Darwin). This one I'm personally very concerned about, even though I do see potential in the above perspective.
3) The molecular clock technique:
Using this technique in its current form suggests, that the human-chimp divergence happened as late as 5-7mya, excluding both Oreop. and perhaps Sahel. as human ancestors (without also being chimp ancestors). Or though some have suggested, that this method can be very inaccurate, as it only proposes values for how often random mutations occur, which may be impossible to predict (similar to Drake's equation). One review of the technique (White et al, 2009) suggests that the point of divergence can be anything from 5mya to 13 mya, making the above possible (or though most repeated experiments with the molecular clock technique conclude values similar to the former).
Either way, the above can only be supported by finding proto-human fossils in the Sahara from the suggested time frame, should they exist. Otherwise, the whole thing is a wild goose chase.
Anyway, another suggestion for the pile.
See perhaps also Evolution of human bipedalism
To CEngelbrecht
Couple of points.
First. Evolution of an aquatic ape would not likely be towards lake dwelling. There is relatively little extra food in lake water. A few fresh water mussels is about it. We cannot accept fresh water fish as part of the deal as they are too hard to catch. Sea water, though, is rich with animal life that is highly edible and can be obtained just by smashing them between two rocks. Thus, fossils should be in marine sediments, and they aint thar!
Second : Hairlessness is not an attribute of aquatic life style. While it is true that cetaceans are hairless, they are extreme cases, which live in water 24/7. The aquatic ape would not be like that, since it would be only partly aquatic. It would be more like seals or otters. These amphibious animals have more, not less hair, and the hair is very dense. This is to hold air for insulation. If an aquatic ape stage existed, the logical evolution would be for a very dense fur coat.
Human functional hairlessness is unique for a terrestrial or amphibious mammal in our size range. The reason it evolved must also be unique. I suggest it evolved because humans invented alternative means of keeping warm, like clothing or fires. No other mammal has done that, so it is a unique reason.
There is not an aquatic ape hypothesis. The various unsupported proclumations by proponents do not satisfy the requirements of a hypothesis.Again, that is such a bizarre exclamation, when AAH-proponents has done nothing but that. There wouldn't be an aquatic ape hypothesis without such demonstrations.Are humans demonstrated to be aquatic or semi-aquatic? Where is that demonstration?Human nakedness is demonstrated to be a general trend for aquatics and semi-aquatics (especially in tropical zones).Observations of Pan sp. find that they are bipedal on land more than in water. Has any study of any primate observed to progress bipedally through water demonstrated that doing so effected any selection?Human bipedality is demonstrated to be a general trend for primates as a subfamily, when moving through water.And demonstrated to be sufficiently available away from water.The need of various nutrients for a healthy development of eg. the human brain is demonstrated as more readily found in aquatic foods.That human infants drown in water 100% is not a demonstration of any aquatic adaptation (besides the whole "human babies swim before they walk" schtick being absolutely groundless).That human infants swims with a high degree of ease before they can walk is an aquatic demonstration.Where is this demonstrated to be the result of a natural history of giving birth in water?That water birth drastically limits the need for episiotomy is an aquatic demonstration.Humans have no trait that is described as being selected for communication under water.That humans communicate via conscious verbal speech is an aquatic demonstration, seeing the only known other example in cetaceans.This is not even true.That human behavior leaves it to be drawn to sand-covered coastal regions in especially tropical zones is an aquatic demonstration.What traits do the descendant populations possess that have been demonstrated to be the result of selection experienced as a result of their migration route, as compared to populations that migrated by other routes away from water?That Homo Sapiens migrated out of Africa along the Southern coasts of Asia and ended up in Australia long before China and Europe is an aquatic demonstration.It is no more an aquatic trait than is running a marathon in record time, or breaking the high jump record. It is a feat of physical training.That humans are instrinsically capable of this William Trubridge 101m CNF World Record Freedive - YouTube , is an aquatic demonstration.colonies like seals and penguins. as aquatic as otters. etc. And backing off from these wild claims, as Algis Kuliukas claims to do does no good, as doing so only requires the same level of congruence with even less selection pressure.
Trying to rule out any 'straw-man' perspective on AAH-opponents, they do tend to share a few key elements, which to me leave them severely weakened in this debate:
One, they seem reluctant to read the actual source texts to eg. Westenhöfer, Hardy and Morgan, but rather prefer this hypothesis be about some sort of ocean-primate, because that version is easy to declare folly. The occasional bong-head with a website going 'wow, we descend from dolphins, awesome' notwithstanding, no serious AAH-proponent has ever suggested more than a beach-ape, a coastal primate with a habitat similar to that of a hippopotamus. The general consensus seems to be that this idea has to be crazy.Oh, very true. It's true of a lot of paleoanthropology unfortunately. Paleoanthropology has been criticised for some time for this tendency. That does not mean that any of the AAT claims have been demonstrated.
Two, they constantly yell and wail that there's no empirical evidence for this or that AAH-argument, but voluntarily ignore that the exact same mind gap is also the case with any land-based argument.In what way is any AAT argument parsimonious?In this mind gap, we can only lean on the principle of parsimony.You mean congruence with aquatic taxa? Hardly.
And thus three, they grossly mal-apply the principle of parsimony, seemingly ignoring that many AAH-arguments have biological precedence,Just as bad is not better, or stronger.whereas many land-based suggestions fail to strengthen its case in a similar way.Nothing is supported by Occam's Razor. What an odd thing to say. The observation that a car has four wheels has absolutely nothing to do with parsimony or Occam's Razor.Saying that AAH is not supported by Occam's Razor is akin to claim that a car with four wheels does not have four wheels.The problem is: the various hypotheses are not supported, are not actually hypotheses. The only proponent to make a testable prediction, Algis Kuliukas, failed to falsify his null. The only bit of science ever done on the topic and it failed. The whole thing is a sad story really. Westerhofer thought we weren't primates, Hardy got carried away with his talk to the scuba club, and Morgan is just an opportunist who thinks nothing of bending the truth into an elaborate smoke bender.
To be fair, I imagine that many AAH-proponents also ignore to read source texts of AAH-opponents, but as an avid reader of Jim Moore's aquaticape.org (about once a year in full, it is indeed the best representation of con-AAH observations), I do make an effort to ignore this 'hunch' of mine that AAH is spot on and be open for any potential Dan Browninitis. Basically, I hate to be wrong. And yet, the site never convinces me that I'm on the wrong track, actually every time I find countless examples of the above misrepresentations. I find countless misquotations and focus on AAH-observations decades old and later retracted.
I've come not to blame Jim Moore for anything (have to admit, I haven't always done that). If this is all a wild goose chase and comparable with Erich von Däniken, he is an admirable proponent for 'keeping it real', which I can use his website for.
Last edited by Eversbane; August 4th, 2011 at 07:51 PM.
In the first place, where has anyone looked? - the transition to bipedalism would be brief in geological time, and not widespread. In the second, we are not talking about "marine sediments" in the anoxic, cold water, bone preserving sense of ocean bottom accumulation and the like: we are talking about shallow water and tide flat stuff, well oxygenated and dense with scavengers and chemically corrosive and not likely to preserve the dead. In the third, behaviorally we don't plausibly have much likelihood of death in this shallow water except by predation - death by disease, injury, even natural disaster, would be more likely back in the trees. And the forest is a poor source of fossils - we still don't have many fossils from the early days of hominidae, despite their apparently wide spread and numbers, until the invasion of drier or otherwise more fossil - suitable habitat.
It demands a large amount of high quality food, especially protein and fat. It does particularly well on seafood, rich in the best nutrition.
And yet we have excellent sequences on a number of aquatic taxa, and brains develop just fine on diets available away from water.In the first place, where has anyone looked? - the transition to bipedalism would be brief in geological time, and not widespread. In the second, we are not talking about "marine sediments" in the anoxic, cold water, bone preserving sense of ocean bottom accumulation and the like: we are talking about shallow water and tide flat stuff, well oxygenated and dense with scavengers and chemically corrosive and not likely to preserve the dead. In the third, behaviorally we don't plausibly have much likelihood of death in this shallow water except by predation - death by disease, injury, even natural disaster, would be more likely back in the trees. And the forest is a poor source of fossils - we still don't have many fossils from the early days of hominidae, despite their apparently wide spread and numbers, until the invasion of drier or otherwise more fossil - suitable habitat.
It demands a large amount of high quality food, especially protein and fat. It does particularly well on seafood, rich in the best nutrition.
This simply continues the problem that the AAT has no evidential support.
iceauraIn the first place, where has anyone looked? - the transition to bipedalism would be brief in geological time, and not widespread. In the second, we are not talking about "marine sediments" in the anoxic, cold water, bone preserving sense of ocean bottom accumulation and the like: we are talking about shallow water and tide flat stuff, well oxygenated and dense with scavengers and chemically corrosive and not likely to preserve the dead. In the third, behaviorally we don't plausibly have much likelihood of death in this shallow water except by predation - death by disease, injury, even natural disaster, would be more likely back in the trees. And the forest is a poor source of fossils - we still don't have many fossils from the early days of hominidae, despite their apparently wide spread and numbers, until the invasion of drier or otherwise more fossil - suitable habitat.
It demands a large amount of high quality food, especially protein and fat. It does particularly well on seafood, rich in the best nutrition.
If pre-humans spent a lot of time in sea water, we should find a lot more fossils in marine sediments than anywhere else. The bones may not end up at the site of death, of course, since the sea is very mobile. Marine sediments are the best place to form fossils, as an enormous wealth of discovered fossils show. And yes, there is a high chance of death while in the sea. Death by disease and by old age would be much less frequent, and death by accident and predation much higher in a primitive pre-human society. So far, to the best of my knowledge, pre-human fossils are found pretty much in all sediment and soft rock (although rare) except marine sediments.
On the brain.
You obviously missed my reference to the elephant, which has a large brain and is highly intelligent, and lives on grass and leaves. Brain size is a function of evolutionary adaptation, rather than type of food eaten. Otherwise whelks would have very large brains!
why do i get a message "You are not authorised to access the web page at http://www.thescienceforum.com/..." when i try to access these links
interestingly enough all I get is white screens when I try
It looks like the trasition to the new software may have resulted in the threads having different id numbers/structures so the pre-transfer links are broke.
Well said Chris, and for Eversbane's doubts, I have some comments.
The so called AAH is not a single hypothesis but a group of hypotheses. They are linked by a common theme -- water, much like the group of hypotheses conveniently called "Savannah hypothesis" have a common theme of open grasslands. Each of the hypotheses has to be verified independently.There is not an aquatic ape hypothesis. The various unsupported proclumations by proponents do not satisfy the requirements of a hypothesis.Again, that is such a bizarre exclamation, when AAH-proponents has done nothing but that. There wouldn't be an aquatic ape hypothesis without such demonstrations.
A curious case is the monk seal, comparable to human as a medium-sized tropical amphibious species. All pinnipeds originated from the arctics, so they are covered by a thick fur to provide extra heat retention, but when they invaded the tropical waters, the monk seals lost their pelage, only a short, non-functional layer of hair is left (possibly used for colorization). This may be comparable to human's loss of thermoregulatory fur, only hairs of other functions are left. We don't see such loss in other comparable species for purely terrestrial reasons.Are humans demonstrated to be aquatic or semi-aquatic? Where is that demonstration?Human nakedness is demonstrated to be a general trend for aquatics and semi-aquatics (especially in tropical zones).
So why the Pan species and other primates, with a significant time of bipedal foraging on land, didn't evolve obligatory bipedalism? What's so special of humans?Observations of Pan sp. find that they are bipedal on land more than in water. Has any study of any primate observed to progress bipedally through water demonstrated that doing so effected any selection?Human bipedality is demonstrated to be a general trend for primates as a subfamily, when moving through water.
OK for ape-sized brains but not for human-sized brains, as demonstrated by medical studies that our mental / physical health is significantly jeopardized by lack of iodine and, in babies case, DHA.And demonstrated to be sufficiently available away from water.The need of various nutrients for a healthy development of eg. the human brain is demonstrated as more readily found in aquatic foods.
It is demonstrated that infants have an innate ability to keep floating on water (not swimming) and dive briefly, which is essential before the learning of more advanced aquatic locomotions. When culturally permitted, babies do learn swimming/diving before walking, as a common fact in the Asia-Pacific coastal peoples.That human infants drown in water 100% is not a demonstration of any aquatic adaptation (besides the whole "human babies swim before they walk" schtick being absolutely groundless).That human infants swims with a high degree of ease before they can walk is an aquatic demonstration.
Anecdotes of natural water birth tradition exist for various aboriginals in Hawaii, New Zealand, American NW coast, etc (unfortunately they were not formally documented before disappearance). Igor Charkovsky's experiments, and large-scale medical research, confirmed that water birth is at least as safe as normal birth procedures, with many significant benefits like no need for episiotomy and pain-killers, a fact that is unthinkable if human is a strictly terrestrial mammal.Where is this demonstrated to be the result of a natural history of giving birth in water?That water birth drastically limits the need for episiotomy is an aquatic demonstration.
Along with syntax and semantics, vocal learning is another major factor to our success in verbal communication. Vocal leanring is only common in birds (which they use a different apparatus called syrinx) and marine mammals, but not in terrestrial ones.Humans have no trait that is described as being selected for communication under water.That humans communicate via conscious verbal speech is an aquatic demonstration, seeing the only known other example in cetaceans.
This goes to the ambiguous realm of Evolutionary Psychology, but is still obvious by the price difference between living places with or without seaview (at least very true in my coastal home town).This is not even true.That human behavior leaves it to be drawn to sand-covered coastal regions in especially tropical zones is an aquatic demonstration.
You got it the wrong way, it's not that Homo sapiens got the aquatic adaptations along the coastal route, but that we must possess those adaptations before we were able to do the migrations. Just like the prerequisites for other routes -- the ability to make clothes and fire for northern areas, or adapt to low oxygen air for mountainous areas.What traits do the descendant populations possess that have been demonstrated to be the result of selection experienced as a result of their migration route, as compared to populations that migrated by other routes away from water?That Homo Sapiens migrated out of Africa along the Southern coasts of Asia and ended up in Australia long before China and Europe is an aquatic demonstration.
The notion that we can achieve everything with physical training is uttery wrong. Consider that our top athletes can't even run faster than an average dog, or the best beer-drinker can't drink faster than a camel, there are unsurpassable limitations in our physical body (= lack of certain evolutionary adaptations). On the other way, consider that no primate can dive for couple of minutes or 10+ meters, while every human can do it easily, and our coastal peoples do it every single day.It is no more an aquatic trait than is running a marathon in record time, or breaking the high jump record. It is a feat of physical training.That humans are instrinsically capable of this William Trubridge 101m CNF World Record Freedive - YouTube , is an aquatic demonstration.
chakazul
Your argument is a bit prone to overlooking inconvenient facts. For example : you compare our hypothetical pre-human aquatic ape to the tropical monk seal. You ignore the great need for any aquatic organism for thermal insulation. Water removes heat at a rate roughly 30 times as great as air of the same temperature. Monk seals get around this with a very thick layer of blubber. Such a layer is not practical for an animal that spends most of its time on land, since it adds too much body weight. Monk seals are very clumsy on land. An aquatic ape could not proceed down the blubber route, due to its need to be agile on land, and would instead have an adaptation similar to the sea otter, with a thick layer of fur, with hairs very close together, for thermal insulation. That has not happened.
You ask what is special about humans that led to bipedalism?
Simple. Humans are the technological ape. Our ancestors used basic technology in every aspect of their lives, from sharp sticks as short spears, to nice rocks to break open rotten wood to get grubs. Carrying tools or weapons requires the fore limbs not being used for locomotion. Our hind limbs are nearly useless for moving through water, but are superbly adapted for bipedal locomotion on land.
Technology is also the most reasonable explanation for functional hairlessness. Hair is needed for thermal insulation, and no mammal is likely to lose that nice, warm hair until an alternative is present. Technology permits warming in other ways, by fire or clothing. Humans are the only terrestrial or amphibious mammal in our size range without hair or a thick blubber layer. We are also the only mammal using sophisticated technology. The two are linked.
You also fall into the trap of believing humans have exceptional aquatic skills. Not so. We are mere neophytes compared to a lot of other mammals that have no specific aquatic stage in evolution. The classic example is elephants, which can swim long distances, and are totally at home in water. Yet they are animals of the forest and savannah. Monkeys and apes can be trained to swim and even dive. There are monkeys living in the mangrove forests of South East Asia that regularly and routinely enter the water to collect food, sometimes by breath hold diving to the bottom to feel around for shellfish. Yet they are adapted to living in trees.
So what are humans especially good at as athletes? Humans are star stamina runners. Only horses are better. A young man who is in the peak of fitness can run almost any other animal into the ground over the long distance. African hunters have been filmed using this technique for hunting. They pick an individual antelope and run at it. It sprints away and stops. The hunter tracks it and catches up. It sprints again. After many such sprint/stop incidents, the antelope cannot go any further. It fails through sheer exhaustion, and the human hunter with his stamina catches up and kills it.
This exceptional running stamina is not characteristic of an aquatic ape. And none of human aquatic abilities are exceptional compared to many other mammals.
As we have found no fossils of the transition anywhere, that's an empty point.
Given where humans are thought to have evolved, we can assume warm water in general.
And humans in general do, visibly, carry an extra layer of fat around on them - an odd adaptation for a distance running animal.
Despite many thousands of years of adaptation to dry land running, we remain superbly adapted to wading and foraging for rich food in shallow water (and carrying our booty to shore). Nothing else comes close.
And this is visible behaviorally, as well. What do humans like to do? What do they do naturally, as children on up, without circumstantial demands, by preference?
Last edited by iceaura; August 6th, 2011 at 06:09 PM.
Why does the infamous fat-layer story never die? It's a feature common in vertebrates and especially so in the mammalian class. How big that layer is depends on several factors - not least of which is diet. Has nobody ever had a steak with a ridiculously large and disgusting subcutaneous fat layer on it? Aquatic cows?
Blame Marilyn Monroe.Why does the infamous fat-layer story never die?
A human being with the fat distribution of a normal chimp is malnourished, starved or anorexic or something. A healthy human female is quite noticeably padded throughout.Uh, yeah, kind of - swamps are their origin And pigs. Check it out. Compare with goats and sheep and turkeys and chickens and llamas and camels and horses and bison and wildebeest and so forth.Aquatic cows?
Responses to iceaura
1. Given where humans are thought to have evolved, we can assume warm water in general.
Aquatic mammals in the tropics inevitably have good thermal insulation. The 30 fold rate of heat removal applies in the tropics also. Water rarely gets above 30 C, and mostly way below that, even in the tropics. As a keen scuba diver who has dived in many tropical locales, I am very familiar with the need for a wet suit, even in the tropics. Human body temperature is 37 C which means rapid heat loss when immersed in water.
2. And humans in general do, visibly, carry an extra layer of fat around on them
This is way thinner than equivalent blubber layers on marine mammals, even in the tropics. I am not a thin person, and I have to wear a wet suit even in the warm tropics.
3. we remain superbly adapted to wading and foraging for rich food in shallow water (and carrying our booty to shore). Nothing else comes close
Tell that to the local herons near where I live. Wanna see real adaptations to wading and foraging! Look no further. You mistake upright stance and long legs for wading adaptations. Upright stance is, as I said before, to permit our fore limbs to be used to hold things, and long legs are for running. We are so badly adapted to the aquatic life style that we cannot even see clearly underwater. I have to wear a face mask when scuba diving to see things!
4. What do humans like to do?
We do what we have been taught to do. When a child first encounters water, that child will be afraid. Curiosity may lead the child to return to the water, but you only have to look to see the fear. I have had a lot to do with people from India, who are not taught, as westerners are, to love the sea (with a few exceptions). It is notable how scared they are of water.
Thanks Skeptic -- skepticism is always a good thing.
Yes, we need to be agile on land as well. If we're amphibious, there will be competing selective pressures -- to keep warm in water, and to be agile on land. I think our fat level is in the middle and meets the two requirements -- not so clumsy as the seals and not so skinny as the apes.
(I'm talking about "we" because I think there was no hypothetical aquatic ape -- we Homo sapiens is the amphibious ape)
The sea otter (and all small-sized aquatic mammals) does not make a good example because of their smaller size, heat lose to the surroundings in much higher rate and subcutaneous fat alone is insufficient, they still need to maintain an expensive fur.
Frankly, it's hard to find a good example to justify or reject any evolutionary convergence... cetaceans live underwater 24/7, most pinnipeds live in polar regions, elephants & hippos are too big, otters & beavers & aquatic rodents are too small... I guess the monk seal is a suitable choice? Isn't it reasonable to consider their relatively thick fat, loss of functional fur, and dark pigmentation as convergent features with Homo sapiens?
Bipedalism: it occurred long before any tools or weapons were made, so it needs purely non-technological reasons, like foraging or child caring (on land or in water).You ask what is special about humans that led to bipedalism?
Simple. Humans are the technological ape. Our ancestors used basic technology in every aspect of their lives, from sharp sticks as short spears, to nice rocks to break open rotten wood to get grubs. Carrying tools or weapons requires the fore limbs not being used for locomotion. Our hind limbs are nearly useless for moving through water, but are superbly adapted for bipedal locomotion on land.
Technology is also the most reasonable explanation for functional hairlessness. Hair is needed for thermal insulation, and no mammal is likely to lose that nice, warm hair until an alternative is present. Technology permits warming in other ways, by fire or clothing. Humans are the only terrestrial or amphibious mammal in our size range without hair or a thick blubber layer. We are also the only mammal using sophisticated technology. The two are linked.
Functional hairloss: Only when people migrated to temperate or polar zones will they need clothes. Look at the hunter-gatherer-fishers in the tropics, only minimum cloths, and we have no reason to assume that our ancestors invented clothes and then abandoned it. So the clothes argument is very unlikely. Fire is a valid argument, though, but we'll need more evidence on that.
Elephants do have amphibious ancestors, so their ability isn't surprising.You also fall into the trap of believing humans have exceptional aquatic skills. Not so. We are mere neophytes compared to a lot of other mammals that have no specific aquatic stage in evolution. The classic example is elephants, which can swim long distances, and are totally at home in water. Yet they are animals of the forest and savannah. Monkeys and apes can be trained to swim and even dive. There are monkeys living in the mangrove forests of South East Asia that regularly and routinely enter the water to collect food, sometimes by breath hold diving to the bottom to feel around for shellfish. Yet they are adapted to living in trees.
I watched YouTube clips that have apes swim slowly, and monkeys dive shortly in shallow depth. Dogs can do these too. I consider these general mammalian abilities because in fact most mammals can do so. However it's a totally different level when we talk about diving down to 100m and holding your breath for 5mins (see CEngelbrecht's link). It definitely needs a complex system of physiological adaptations, and if not, we would wonder why other land mammals can't do it and won't do it.
In fact I don't reject the idea that humans are also adapted to endurance running. Our strong legs, foot archs and sweating are the features need to be acquired (either as adaptations or pre-adaptations). The seemingly conflicting ideas that we are water-adapted (AAH claims) and also land-adapted (savannah model claims) are not mutually exclusive, and in fact need to be reconciliated because each of them are telling one side of the whole story.So what are humans especially good at as athletes? Humans are star stamina runners. Only horses are better. A young man who is in the peak of fitness can run almost any other animal into the ground over the long distance. African hunters have been filmed using this technique for hunting. They pick an individual antelope and run at it. It sprints away and stops. The hunter tracks it and catches up. It sprints again. After many such sprint/stop incidents, the antelope cannot go any further. It fails through sheer exhaustion, and the human hunter with his stamina catches up and kills it.
This exceptional running stamina is not characteristic of an aquatic ape. And none of human aquatic abilities are exceptional compared to many other mammals.
Chak
The main difference is in the distribution and properties. Cows and pigs (and yes, unhealthy middle-age men and apes) have their fat mostly inside abdomen, and marine mammals (and healthy women) mostly under their skin. Obviously they're used for different functions and acquired under different selective pressures.
Iceaura,
I think it's far more likely that my steak was fatty due to selective breeding and the cow being very well-fed. You're right though - and I should've realised - that the ancestors of modern cows possibly did frequent watery environments. I've no idea how fatty their auroch ancestors were though. It's a dangerous game to play when one starts picking various creatures as examples since it's all too easy to find an equal number of counter examples: There are aquatic animals with very little subcutaneous fat and purely terrestrial animals with a lot of fat. Such selective observations are, for me, one of the main irritating factors of the AAH. It's bad science. What about seasonal variations in food supply? Could that be a more effective explanation?
chakazul,
The bodily distribution of fat in humans does not suggest that it would be of much use at preventing heat loss due to prolonged immersion in water. I'd love to see a bioenergetics study of just how effective it is or not. In general, fat would appear to be primarily about energy metabolism and storage; it's also used in certain groups to provide hydrodynamic streamlining to the body. It's also pretty essential to normal physiology for various reasons. In the case of humans, that fat layer would be wholly ineffective (my guess, until convinced otherwise) at doing what the AAH claims. Its distribution is wrong and the observed differences between the sexes (apples versus pears) also needs addressing.
I'd also point out that my fatty steak had subcutaneous fat on it, not visceral fat.
So are you arguing my case for me? More than one person has commented on how very "human like" a large crane is, for example. Bipedal stance of course comes natuarally for birds, as opposed to reptiles or mammals - and we see mostly birds wade foraging.
Humans are better foragers, of course - take a wider variety of foods, hunt at night as well as day, easily handle much greater water depths and habitat circumstances, and so forth.
Humans can play - for fun, without critical discomfort or any economic reward - in fairly cold water for hours.
And that's after thousands of generations of adaptation to running across savannah and other dry land, in extreme heat.
When they first encounter waterside environs, children need watching so they don't drown themselves while having fun. Little or no instruction is required, for the fun part.
You take a hundred kids to a park. There's a lovely hundred acre meadow, a nicely paved lot, a beautiful hundred acre woods full of interesting trees easily climbed, and an ordinary fifty yard pebblesand beach on a clean lake. Come back in two hours. Where do you expect to find most of the kids? From anywhere - India, anywhere.
Healthy pigs and cows carry significant subcutaneaous fat. They also feature semi-amphibious genetic heritages, and modern preferences for swamp and wetland habitat. Pigs make an especially interesting example, for their circulatory and dietary similarities with people - and they are about the same size.
The critics of AAH are generally worse, significantly more indulgent in such things. Of course seasonal variation in food supply affects fat deposits - but we're talking about a fairly even layer of subcutaneous fat, not a dedicated storage feature, and meanwhile the notion conflicts with the running adaptation - often advanced by the same people.
The things is: sure the aquatic side trip is speculative, but it's not wrongheaded and borderline ridiculous as an explanation for a couple of key features, such as bipedalism. Most of the counter offerings, even some accepted into conventional wisdom, are. To carry tools? To see over tall grass? To enable face to face sex? To cool off in the heat? To take advantage of the opposable thumbs? C'mon.
Last edited by iceaura; August 7th, 2011 at 01:49 PM.
btw: re thisCSI Activities (Surin Islands, Thailand)We are so badly adapted to the aquatic life style that we cannot even see clearly underwater. I have to wear a face mask when scuba diving to see things!
Let me make a general comment here.
Humans are superb generalists. We climb trees. We dig burrows. We dig up edible roots. We hunt with artificial fangs and claws. We run. We swim. We travel. Humans are the only mammal to colonise all continents without assistance. (Rats and mice have done the same, but only on human coat tails.)
As such superb generalists, we can exploit salt water. This exploitation is mistaken by some as signs of an aquatic stage in evolution. Not so. We are not adapted to the aquatic environment. I speak from strong personal experience. I am one of those who loves the sea, and especially loves scuba diving. I am also painfully aware from experience just how poorly adapted I am to that environment. I see other species in the sea on a regular basis, from fish to mammals to birds. They can all swim rings around me, and stay underwater far longer if I do not use artificial aids.
Sexual reproduction creates genetic variability, and that means there will always be a few people who are better suited to specific activities. A great marathon runner here. A great sprinter there. A great swimmer elsewhere. And even the occasional person who is great at holding his breath. The occasional person who is great for breath hold diving after extreme training is not a sign that the species as a whole is adapted to that. I consider myself to be average for that skill, but have trained hard. I have breath hold dived to 17 metres (55 feet), using extreme effort. Even a bloody shag can do much better! Damn it!
Underwater vision. Sure the ability to see underwater varies, and like so much else, improves with practise from childhood. But humans are not adapted to see underwater, and our underwater vision stinks. That is why I wear a face mask.
Carl Zimmer's blog "The Loom" has an interesting graphic on it, taken from a paper in Nature. The authors try to reconstruct the vegatation cover for two important fossil localities over the last six milion years by examining carbon isotope ratios in paleosols.
link to article
link to graphic
Try taking it off every once in a while and see what happens. My own diving experiences have shown that the eye can be trained to see 'adequate' under water. Having trained freediving since 1997, I have a habit of not wearing goggles at the start and end of a training session. At one point, I tried to dive without a mask on open water dives, first on diving vacations in Egypt, then in Scandinavian waters. On one dive, wearing only my nose clip, I noticed I was heading towards a burning jellyfish and quickly surfaced. Only afterwards I considered that I had reacted to underwater vision input without a mask.
I am not saying I can read under water, but I find no problem orientating in clear and lighted water. After a number of years training, my eyes seem to have adapted themselves to a certain degree, similar to that of the so-called Sea Gypsies. And that's an athletically average Northern European who has suffered from stigmatism since birth.
And note that some aquatic and marine mammals have poor under water eye sight, eg. sirenes and hippos.
Also check this video to widen the perspective on children's fear of water:
BBC - BBC Two Programmes - Wild, Wild Tribe - Reef Gypsies, Free-diving skills
(Not that children should be unsupervised at the beach.)
And be wary of thinking too 'European'/'Western' in these matters. We have only been a temperate primate for little over 30.000 years (Cro Magnon, not counting earlier strains of Neanderthal and Erectus). All other humans before that are tropical primates. Our behavior in colder waters may not be an indicator in this debate, and we'd be better off looking towards tropical peoples.
On the flip side, it's an ok argument that humans may be superb generalists, capable of adapting to anything even in the same generation. But I can't imagine a three day old baby and it's 95-year-old great grand mother enjoying a 'vacation' on open grassland or in a thick jungle, where as there's nothing more enjoyable for both of them but to sit all day long on the beach 'playing' in the sand and looking out over the ocean. Regardless if they descend from Africa, Europe, Asia or the Americas (granted, temperate peoples may need more sunscreen, but ...).
CEngelbrecht,
Our fascination with the seashore has relatively recent origins. Perceptions of things change for all sorts of reasons. This is not an evolutionary hang-over from a past aquatic phase.
Ok, a valid point. Those kind of arguments based on human behavior may be based on short-termed cultural whims. And human cultures live in a chaos mathematical realm, with countless random variations mixed from the human survival instincts.
However, it strikes me as peculiar to consider where humanity live today in most numbers. Consider a map over the global human population density, and you'd be perplexed by just how many of us live along river beds and sea coasts. Almost one third of the current world population live along the Chinese and Indian rivers and coasts in Southern and Eastern Asia. Aparently, that's where the best survival conditions are for Homo Sapiens.
And people's quick counterargument on that is always, "We live there, because that's where the most food is." Excuse me, but the largest potential ammount of food would actually be found on the central Asian plains, eg. in Russia. Even if the large ammount of people in China and India is simply due to the recent advent of agriculture (even though Homo Erectus also found the Chinese rivers and the Indonesian archipelago long before agriculture), it doesn't explain why we haven't spread equally further out onto the plains of Asia, so that all of Asia would be colored on that map. Especially if we are supposedly a grassland ape. Or, if we're a woodland ape, why we don't exist in the scores of millions in African and East Asian jungles or European forests.
It may be correct, that it's difficult to use behavioral arguments in this debate. But even if we focus solely on physiological arguments, it is very difficult to find an evolutionary force that would explain the key features in modern and past humans in the suggested, non-aquatic scenarios, in view of lacking biological precedences. And when these features can be compared somewhat easily with that of aquatics. Even though at some crazy level it's possible that humanity made up its own rules and started making peacock's tails left and right through its evolution, it is not very likely. Parsimony screams that we adhere to the same evolutionary principles as all other biological life forms on planet Earth, and that our features would have convergent precedences elsewhere.
Quite frankly, I don't understand what the problem is, this idea is a no-brainer. And I'm sure that 50 years from now, anthropologists are gonna have the same short term memory loss as geologists with Wegener and say something like, 'We knew it all along, we just needed to secure the evidence first." That they wil have forgotten these times out of shame, when all they want is to secure evidence against it.
Chris,
I don't think it's relevant for the AAH that with our modern technology and farming practices we can turn Kazakhstan or the South Siberian Plains in to a giant wheat field. For human habitation, those sorts of places are quite resource poor and climatically harsh.
We did none of that except tree climibing until after we became bipedal hominids - so none of that explains the transition.
You are well adapted to tropical, amphibious, forest edge, shallow water, wade foraging - marine environments, like desert or montane or savannah or tundra or prairie or temperate zone forest environments, require technology.
Drop a naked ten year old child into the ocean at a random place without resources or special training, and they will probably die in a couple of days. They might last a couple of days longer in the desert, prairie, mountains, savannah, temperate zone forest (if lucky in the season). On the shore of a lake, river mouth, or similar environment in the tropics, they might live for years with reasonable luck.
The transition from quadrupedal ape to bipedal hominid, with the other coincident and possibly concurrent adaptations in thumb structure, fat distribution, behavioral preferences, dietary preferences, breath control, brain size and structure, etc, is what we are considering here. The subsequent geographical radiation and environmental niche expansion of this new kind of ape apparently came later, with tools and emergent options. We became modern superb generalists in consequence of, not in preparation for, our novel bodies.
This is one of those fascinating ideas that illustrate the reality that humans will choose to believe anything that appeals to them, whether there is adequate evidence or not.
The people who contribute to this forum are mostly pretty smart. In spite of that intelligence, there is a bunch who are trying hard to make a case for an aquatic ape stage in human evolution, and I can see why. It is a very romantic and attractive idea. Finagle only knows, I find the idea very attractive too, since I am a person who loves the sea.
In spite of all this, the 'evidence' that is used is forced and unconvincing. We have someone trying to say that : "Sure, we cannot see well underwater, but, hey, the blurred signal does bring at least a little information, so we must be adapted to underwater vision." Or else : "Some people have slightly less blurred vision, so they must be adapted."
The functional hairlessness of humanity is clearly nothing to do with aguatic existence, since we are totally unprepared for the extreme heat loss when immersed. The hottest sea water in the world (excluding geothermal) is near the equator. Such as Papua New Guinea where I have done a lot of scuba diving. I can stay in that water for up to an hour underwater with no wet suit, but I am shivering afterwards. And I have more subcutaneous adipose tissue than most. Humans are just not adapted to thermoregulation in immersion, even in the hot tropics.
CEngelbrecht thinks that living on coast or river is evidence. Not so. Such towns and cities are there for transport reasons. Barges and ships are the best way to deliver goods in bulk, and humans make good use of that. Especially 100 plus years ago, when most were founded.
The Engel points to the fact that human physiology and physical adaptations are unique. Sure. They are unique and not shared by amphibious mammals. Our uniqueness comes from the fact, as I said before, that we are the only species using relatively sophisticated technology. Definition of sophisticated technology is anything from stone tipped spear and more advanced than that. We should be called Homo technologica, rather than Homo sapiens. We are adapted to using technology, and to its effects. We are functionally hairless because we have alternative methods of keeping warm, based on the technology of fire and clothing. This gives humanity the ability to shuck off clothing when a period of intense exertion is required, such as hunting, permitting a massive increase in physical performance.
Iceaura is concerned about the transition to bipedalism. Technology explains that most handily. Upright stance freeing fore limbs to handle and carry tools and weapons.
Iceaura naively thinks you can place a 10 year old next to the sea and he will be able to survive. Yes, but only with appropriate training. Which also applies to every other environment. A 10 year old raised in the rainforest, and trained to collect food and build shelter could likewise survive there. It is all about knowledge and skills.
There is nothing special about humans as aquatic beings. We can handle it to a degree because we are superb generalists. But we are equally at home in the rainforest, steppes, or even desert. Knowledge and skill is enough to permit humans to thrive anywhere. Just look at the Inuits!
It's seen in humans, chak, but before you claim congruence with monk seals you will need to provide evidence of congruence with monk seals. Are you claiming an aquatic natural history for humans that is comparable to monk seals, or are you just drawing a thermoregulation analogy? Because thermoregulation is already a hypothesis within the realm of human natural history, and there is a terrestrial analogue - the Patas monkey. They have not lost all their hair yet, but they are second only to humans in sweat production per square unit skin area, and second only to humans in the ability to depress core body temperature under heat stress. And they live on the savannah.A curious case is the monk seal, comparable to human as a medium-sized tropical amphibious species. All pinnipeds originated from the arctics, so they are covered by a thick fur to provide extra heat retention, but when they invaded the tropical waters, the monk seals lost their pelage, only a short, non-functional layer of hair is left (possibly used for colorization). This may be comparable to human's loss of thermoregulatory fur, only hairs of other functions are left. We don't see such loss in other comparable species for purely terrestrial reasons.Are humans demonstrated to be aquatic or semi-aquatic? Where is that demonstration?
lolz. "If we evolved from monkeys, why are there still monkeys?"So why the Pan species and other primates, with a significant time of bipedal foraging on land, didn't evolve obligatory bipedalism? What's so special of humans?Observations of Pan sp. find that they are bipedal on land more than in water. Has any study of any primate observed to progress bipedally through water demonstrated that doing so effected any selection?
nice, chak. worthy of Algis.
In specific populations that vary quite a bit from standard ecomonic and subsistance practices. You cannot bring data to bear that shows anyone with access to varied resources likewise available to our ancestors suffers any significant detriment from such a diet. If you can, bring it. Provide citations.OK for ape-sized brains but not for human-sized brains, as demonstrated by medical studies that our mental / physical health is significantly jeopardized by lack of iodine and, in babies case, DHA.And demonstrated to be sufficiently available away from water.
Any infant of an age before walking (not that walking has anything whatsoever to do with the ability to self-prevent drowning) will drown - 100%. There is no evidence of selection in the baby swimming argument.It is demonstrated that infants have an innate ability to keep floating on water (not swimming) and dive briefly, which is essential before the learning of more advanced aquatic locomotions. When culturally permitted, babies do learn swimming/diving before walking, as a common fact in the Asia-Pacific coastal peoples.That human infants drown in water 100% is not a demonstration of any aquatic adaptation (besides the whole "human babies swim before they walk" schtick being absolutely groundless).
"Unthinkable?" What does that mean? Does that mean you don't have any evidence of selection for a natural history of giving birth in water?Anecdotes of natural water birth tradition exist for various aboriginals in Hawaii, New Zealand, American NW coast, etc (unfortunately they were not formally documented before disappearance). Igor Charkovsky's experiments, and large-scale medical research, confirmed that water birth is at least as safe as normal birth procedures, with many significant benefits like no need for episiotomy and pain-killers, a fact that is unthinkable if human is a strictly terrestrial mammal.Where is this demonstrated to be the result of a natural history of giving birth in water?
Anecdotes. pshaw!
Humans have no trait that is described as being selected for communication under water.Along with syntax and semantics, vocal learning is another major factor to our success in verbal communication. Vocal leanring is only common in birds (which they use a different apparatus called syrinx) and marine mammals, but not in terrestrial ones.Humans have no trait that is described as being selected for communication under water.
'nough said.This goes to the ambiguous realm of Evolutionary PsychologyThis is not even true.
It wasn't my hypothesis.You got it the wrong way,What traits do the descendant populations possess that have been demonstrated to be the result of selection experienced as a result of their migration route, as compared to populations that migrated by other routes away from water?Then there's no argument here.it's not that Homo sapiens got the aquatic adaptations along the coastal routeWhat adaptations?, but that we must possess those adaptationsHence, no argument here.before we were able to do the migrations.Now you say there is no difference between the routes = no argument here.Just like the prerequisites for other routesHas absolutely nothing to do with the argument presented.-- the ability to make clothes and fire for northern areas, or adapt to low oxygen air for mountainous areas.
That was not my argument.The notion that we can achieve everything with physical training is uttery wrong.It is no more an aquatic trait than is running a marathon in record time, or breaking the high jump record. It is a feat of physical training.Such was never a survival requirement. Why should we?Consider that our top athletes can't even run faster than an average dogNot the camel argument again, chak!, or the best beer-drinker can't drink faster than a camelIndeed., there are unsurpassable limitations in our physical body (= lack of certain evolutionary adaptations).lolz. You switched gears, there, chak. You drew comparisons to dogs and camels but failed to specify a comparison to anything aquatic. It remains that it takes a tremendous amount of training for a human to make a 101m dive that a newborn cetacean could make on its first breath. This is the comparison you wanted to make, chak.On the other way, consider that no primate can dive for couple of minutes or 10+ meters, while every human can do it easily, and our coastal peoples do it every single day.
Now provide the evidence that the abilities, as pitiful as they are, that humans do have in water are actually the result of selection due to association with water. This is where the AAT keeps falling down.
Indeed, underwater visual acuity has been demonstrated to be a learned feat. Anyone can learn it.Try taking it off every once in a while and see what happens. My own diving experiences have shown that the eye can be trained to see 'adequate' under water. Having trained freediving since 1997, I have a habit of not wearing goggles at the start and end of a training session. At one point, I tried to dive without a mask on open water dives, first on diving vacations in Egypt, then in Scandinavian waters. On one dive, wearing only my nose clip, I noticed I was heading towards a burning jellyfish and quickly surfaced. Only afterwards I considered that I had reacted to underwater vision input without a mask.
I am not saying I can read under water, but I find no problem orientating in clear and lighted water. After a number of years training, my eyes seem to have adapted themselves to a certain degree, similar to that of the so-called Sea Gypsies. And that's an athletically average Northern European who has suffered from stigmatism since birth.
And note that some aquatic and marine mammals have poor under water eye sight, eg. sirenes and hippos.
Also check this video to widen the perspective on children's fear of water:
BBC - BBC Two Programmes - Wild, Wild Tribe - Reef Gypsies, Free-diving skills
(Not that children should be unsupervised at the beach.)
And be wary of thinking too 'European'/'Western' in these matters. We have only been a temperate primate for little over 30.000 years (Cro Magnon, not counting earlier strains of Neanderthal and Erectus). All other humans before that are tropical primates. Our behavior in colder waters may not be an indicator in this debate, and we'd be better off looking towards tropical peoples.
On the flip side, it's an ok argument that humans may be superb generalists, capable of adapting to anything even in the same generation. But I can't imagine a three day old baby and it's 95-year-old great grand mother enjoying a 'vacation' on open grassland or in a thick jungle, where as there's nothing more enjoyable for both of them but to sit all day long on the beach 'playing' in the sand and looking out over the ocean. Regardless if they descend from Africa, Europe, Asia or the Americas (granted, temperate peoples may need more sunscreen, but ...).
Do you understand the implication of that?
The implication of that is that there is no evidence of any genetic variation between modern human populations for this feat, irrespective of whether any particular population associates with water or not.
Even then, the acuity that can be achieved is not great compared to mammals that actually have undergone selection due to association with water.
Also, we have no idea of the capability of other primates to achieve the same feat, although we know that quite a few Catarrhines monkeys swim, even foraging underwater. So if you want this ability to be a trait selected by association with water, then push it back onto our Catarrhines ancestors.
Are you familiar with Algis Kuliukas' experiment tossing human and chimp babies into water to record the relative rates of survival? This is exactly the same argument.
No. A human 10yo will not last more that a few days, if that, in a tropical near water setting. Not even.Given the hominid basal condition with respect to bipedalism, as compared to the other extant African apes who are derived toward various arboreal specialties, and given that hominids are the African ape that gave up the trees, it is entirely likely that bipedalism as we see it evolve in the hominid lineage might have been nothing more than the consequence of a Late Miocene/Early Pliocene ape giving up the trees. It might be more proper to look at how they could have given up the trees.
The transition from quadrupedal ape to bipedal hominid, with the other coincident and possibly concurrent adaptations in thumb structure, fat distribution, behavioral preferences, dietary preferences, breath control, brain size and structure, etc, is what we are considering here. The subsequent geographical radiation and environmental niche expansion of this new kind of ape apparently came later, with tools and emergent options. We became modern superb generalists in consequence of, not in preparation for, our novel bodies.
One hint is seen in Orrorin tugenensis where we see modifications in the femur toward obligate bipedality combined with modifications of the dentition that would have allowed increased consumption of terrestrial plants. The bipedality might only have been a consequence of reduced selection for arboreal capability. Other variations are not necessarily related to each other: i.e. breath control doesn't necessarily have anything to do with bipedality (although there is a link hinted at in the locking of respiratory rate to stride rate). One should not assume causations between traits - that would require evidence of causation. That bipedality might be simply the result of reduced selection for an arboreal lifestyle is the null hypothesis against which positive selection alternatives much make their case. And, again - that requires evidence.
Returning to fat layers:-
Could someone kindly provide me with a few references to some free and easily accessible literature (preferably something published in an appropriate journal) on what is different, special or unusual about the supposed aquatically-adapted fat layer in humans? As far as I can tell it's a feature that is very common in the vertebrate lineage, particularly in mammals - including the non-human primates. It's only slightly odd character is the observed differences in bodily distribution between the sexes (unexplained by AAH) and it's typical thickness (which is easily explained by diet). AAH-peddlers repeatedly claim that humans are unique among primates in having this fat layer, so I'd like to see some actual evidence.
All I can find is an oft-quoted reference to a 1929 paper by F. Wood-Jones, "Man's place among the mammals"* which apparently has been used to state that the human subcutaneous layer of fat is lacking in other primates. Can't find the book itself though, so can't be sure. It would appear though that this is the likely source for the claim. Any thoughts on that? I'm inclined to assume that a single reference has been quoted and quoted for decades so that it now, to some at least, appears as fact and is never questioned. Given the pervasiveness of the fat-story in AAH literature one would like to assume that the claim has a solid scientific foundation. Since I can find dozens of studies on primate subcutaneous fat without trying very hard, as well as numerous studies on non-aquatic mammalian superficial fat deposits in general, I'm inclined to discount this reference as inaccurate.
Any suggestions would make welcome reading.
* I stumbled across this reference in a 2002 letter published in Molecular Biology and Evolution, where one paragraph begins: "One long-noted basic anatomical difference between humans and chimpanzees is the human subcutaneous layer of fat which is lacking in other primates (Wood-Jones 1929, p. 309)".
Mol Biol Evol. 2002 Dec;19(12):2342-5.
Selective sweeps in the human genome: a starting point for identifying genetic differences between modern humans and chimpanzees.
Diller KC, Gilbert WA, Kocher TD.
The human subcutaneous fat layer is most definitely not homogenous. This is especially true in males. In the female of our species, it is more so, and appears to have the same function as breasts. ie. enhancing sexual attractiveness by creating smooth curves.
Thermal resistance has been tested between men and women. In spite of the myth that the fat in women gives better resistance to cold, it turns out to be the opposite. Men are more resistant to cold - doubtless because of the greater body mass.
Primitive peoples with poorer diets have considerably less cold resistance than modern, over-fed, man with his extra bulk. Sizeable fat layers in humans are not 'natural'. The 'natural' appearance of a primitive human, and presumably prehuman also, is skinny.
I have a complete inability to understand why AAH proponents find fat so fascinating and convincing for there's yet to be a single credible piece of evidence presented on this forum so far that can satisfactorily explain this (even though this is not a unique feature at all) as an adaptation to immersion in water. The standard fare appears to be to compare two organisms with vastly different life styles that are separated by the best part of 100 million years of evolution and leave it at that. Everything seems to be little more than ill-informed speculation and ignores the rather obvious: a thin layer of fat is a crap thermal insulator when compared with fur.
Although I'm not a pro swimmer / diver, my experience told me that when swimming in cool water, the only time I shivered is when jumped in and when came out from water, in-between I can stay like 1-2 hours without feeling cold. This fact always surprised me because the water felt so cold. I guess it has something to do with water's heat capacity (less temperature fluctuations)?
For ethnological examples, there are the Ama divers in Japan and Korea. They (mostly women) used to dive for oysters as food (now dive for pearls for $$), and even for the deep cold water of Japan Sea, they dive naked. At one hand, they demonstrated our free-deep-diving ability as a common trait, also demonstrated is our efficiency of heat retention in deep diving -- at least in women.
This makes me suspect that, perhaps women are more adapted to diving, provided their thicker and more evenly distributed fat, more streamlined body, and (not entirely jokingly) being more vocal (i.e. talk more than men). That may be caused by a possible "sex role" of diving for food, spending more time in water. In contrast, men are more muscular, more adapted to running, more skillful in making tools / weapons, being explanable by a possible sex role of hunting. Apparently this is only my unfounded speculation (some here will ridicule it without mercy!) but as far as it seems fit some descriptions of our sexual dimorphism, I would like to find more evidences.
At least, I suggest to examine the two sexes of our species independently. The huge differences in morphology and behavior (compare to other primates) call for our special attention.
If you tried considering the actual speculations advanced, rather than your continual rewritings of them, you might find understanding easier.
The context: we speculators in an amphibious phase of hominid evolution are not even attempting to exclude or deny the subsequent evolution of hominids into humans. In particular, the speculations of adaptation to hot weather mid day running seem very well supported, by the hair loss and sexual dimorphism and various structural features - including even the larger brain. See Berndt Heinrich's now dated but well put arguments.
But much of human structure is very poorly explained as adaptation to savannah running. It makes no freaking sense that humans adopted bipedalism, grew a layer of fat, developed opposable thumbs, radically modified their breath control and vocal structures, and so forth, as an adaptation to a mysteriously taken on niche they were initially so poorly suited for. It doesn't fit the timeline, it doesn't have an incremental mechanism, it doesn't add up.
re the fat: Humans are covered with a layer of fat not present in other primates and rare to absent in dry land hot weather mammals. That's an observation, and you can make it for yourself. It's especially obvious in children, and women. It isn't a proper layer of blubber, but then much has changed in the past million years. It does help insulate against the cold, thin as it is, and heat loss is a critical factor in amphibious foraging - a thicker one, of which this is the remnant, would be even more effective, especially if it were a continuation of the layer of special brown fat human babies (and no other primate babies) feature.
It's just one observation. It's not a fascination. It's just ordinary. And its counter arguments are stuff like this:The dimorphism between the sexes supports the AAH readily, because the AAH explains its existence and distribution in the first place. There's something for sexual dimorphism to work with - the running ape speculation, with its wealth of evidence and support, easily supplies the sexual selection advantage once the fat layer is present. And diet does not begin to explain its thickness - women and children without it are starving, not simply on a different diet. You bring a human baby with the fat distribution of a well fed healthy baby chimp into a hospital, and the docs will start running emergency tubes. You stuff a baby chimp with butterfat for months, it will still have skinny arms and visible jawbones, collarbones, etc.
Well, no, fat is a better insulator than fur in the water. But you make a good point - hairlessness is not explained by an aquatic phase. Why is that an argument against an aquatic phase? Don't most people think that loss of hair came long after bipedalism, etc? The "running ape" speculation has us losing the hair long after we developed tools, fire, speech, and a dry land foraging niche. It is postulated as an incremental advantage to an ape already up on two legs, foraging long distances on the ground, carrying food back and gear with them, etc. And it seems more than a little plausible, in that context - lots of evidence, lots of mechanism, agreement with the timeline, etc.
But something has to get that ape up on its hind legs, controlling its breath with radically modified structures, wrapping itself in expensive fat, manipulating with its thumbs, and thinking hard about fairly complex stuff, for hours every day and thousands of generations on end. And this is where the cavalier dismissal of the AAH becomes a bit irritating - because the proposals that are taken seriously are comparative garbage, frankly. Comedy fare. Seeing over tall grass? Carrying tools? Allowing face to face copulation? Walking on tree branches? Please.
Last edited by iceaura; August 10th, 2011 at 02:14 AM.
Iceaura,
If you tried considering the basic biological facts then you might understand my criticisms of the AAH in regards to fat a little better. Can you provide a single credible reference (I ask this for the second time) that demonstrates that a subcutaneous fat layer is not present in non-human primates? It is not a uniquely human feature amongst primates. It does have some features that are of interest and require explaining - such as fat levels in neonates - but nothing that would require a comedy aquatic explanation. That this fat is more abundant in modern humans can be adequately explained by diet. The idea that it actually forms a "layer" as such is also not strictly true. It's a loose connective tissue with varying amounts of adipocytes that tend to accumulate in some places more than others. This tissue evolved early in the vertebrate lineage and has many, many functions; the relevance of insulation among these functions is not all that clear.
Sexual dimorphism for fat distribution does not support the AAH. Not even close. A far more elegant hypothesis would be to consider the differences between the sexes as a measure of sexual attractiveness: fertility and reproductive capability. And again, sorry, but a thin layer of fat is a poor insulator when contrasted with fur - both in water and on land. This is a fact. Hence, it is a very major criticism of the AAH. Can you provide references that demonstrate the effectiveness of fat over fur? Recall also that the AAH tries to explain loss of fur as an aquatic adaptation.
When it comes to fat the AAH rests upon what I see as two very flawed ideas that have no evidentiary support: unique fat and its thermal advantages over fur. So I repeat: it's all ill-informed speculation. Then again, maybe it is I that needs to be better informed? Show me the evidence.
I don't find your comedy fare all that amusing, for I don't recall ever lending any support to such notions as those you like to continually put in my mouth.
Subcutaneous tissue - Wikipedia, the free encyclopedia
I need to ask you, do you take a shower every day? If so, why?a comedy aquatic explanation
tumblr_l3t9lqpI8L1qar3s3o1_500.jpga thin layer of fat is a poor insulator when contrasted with fur - both in water and on land. This is a fact.
Last edited by CEngelbrecht; August 10th, 2011 at 09:37 AM.
CEngelbrecht,
What specifically about that wiki article am I supposed to be reading? In several places it confirms what I have been saying all along.
Edited to reply to your edit:
No, I don't shower every day for a variety of reasons. Why?
The seal picture is not relevant to the question I posed.
Hi Zwirko,
In fact, I found that sexual selection (= measure of sexual attractiveness) may not adequetly account for our sexual dimorphism.
First, when considering the whole animal kingdom, it is almost always the males that are modified by sexual selection, like the extravagant feathers in birds, the horns of dear, or the facial feature of orangutans. In human's case, strangely, it's the females that have many features seems modified and deviated from the primate norm.
Second, those modifications are usually adornments (though sometimes develop to a ridiculous level), but rarely invasive modifications like lose of functional fur.
Third, being a human by myself, of course I consider a female body attractive, with the beautiful curves, big boobs, big buttocks, smooth skin, and long legs. But I can't imagine how would a chimp (or more appropriately an Australopithecus) found such properties attractive in the first place -- he should find a female losing hairs, having weird body proportions and lacking a red buttock unattractive. That is, sexual attractiveness is more likely the result, not the cause, of they acquiring those features.
About the effectiveness of our fat, referring to my last post, I found that a thin layer of fat mostly like exist in healthy men (except the beer belly that proven to be an unwanted feature), while healthy women always have a moderately thick fat covering most of their body. The fat layer serves them well in providing buoyancy during swimming, and keeping warm during diving, as examplified by the Ama divers dive naked in the cold Japan Sea, and women being the champions in long distance open water swimming.
Interestingly, compared to man, woman is also the sex that has less body hair, smoother skin, more streamlined morphology, and behaviorally more attracted to beaches and coasts (based on my observation of friends), etc.
So, the AAH arguments seems not so outrageous at least for half of our species?
Chak
This is easily explained by the fact that the males of the species mentioned do not provide for their families in the way that humans do. A buck deer will add any number of doe to his harem, no matter what they look like. He loses nothing. A beautiful woman, on the other hand, will have her pick of a number of men, and may choose the one offering the best prospect as provider for her and her offspring.
You really think they are streamlined??Interestingly, compared to man, woman is also the sex that has less body hair, smoother skin, more streamlined morphology,
Can anyone explain where the fat layer is that is being referred to?
From the images that are available of tropical lowtech tribes of humans, there seems to be very little fat present on the body, and what little there is is not placed in areas or quantities that would be viable as a heat conservation method.
Once more the fat. Sigh.
Our fat layer is easily explained in terms of running. Humans have possibly the best cooling system found in all mammals. We have almost no fur, and sweat glands over almost the whole body. When we run, the blood flowing to the skin is cooled by the evaporation of sweat. The cooler blood flowing back inside cools the rest of the body. However, when we are not running, a degree of thermal insulation is advantageous. A thin fat layer assists this. The thin fat layer, in combination with clothing and fire, provides the thermal insulation all mammals need. If we used hair or fur instead of fat for thermal insulation, the cooling mechanism would be severely impaired, and we could not run the way we do.
The fat layer is far too thin, though, to confer any benefit in water immersion. As I pointed out before, heat loss is 30 times greater in water than in air of the same temperature. To counter that with fat alone requires a very thick layer of blubber, like that of the monk seal, but totally unlike that of humans.
Bipedalism is also vital for our running. The only reason humans run with great stamina is to hunt. So if we ran on all fours, what the hell would we do when we caught the prey? Bite it?
Human stamina hunters carry spears. They need to run bipedally to free the forelimbs for carrying and wielding spears. Otherwise there would be no point running at all. The enormous stamina shown by young male hunters indicates that bipedalism is no handicap to stamina running. It is a major handicap to sprinting, of course, and any prey animal can out-sprint us. But with good tracking skills and stamina, over the longer event, the human will run down a deer or antelope every time.
If iceaura cannot see how good breathing and opposable thumbs are useful in stamina hunting, then I cannot help him!
Iceaura also thinks fur is not good for aquatic insulation. Tell that to the sea otter, which lives 24/7 immersed in the frigid waters of Alaska, and has little fat. It has, however, very dense fur that is a very effective air trap. Superb insulation. Seals and other pinnipeds normally rely mainly on fur also, though they will also have a fat layer. Seal skins were once regarded as the premium source of warm fur coats, due to their luxuriant fur. This is something the Inuit knew very well indeed! Fat is a good insulator in water only if the layer is very thick. This is not the case with humans.
I also have to point out that stamina hunting requires a light weight body. Fat will be at a minimum for that hunting style, making it useless for immersion.
Chakazul said :
"Interestingly, compared to man, woman is also the sex that has less body hair, smoother skin, more streamlined morphology, and behaviorally more attracted to beaches and coasts (based on my observation of friends), etc.
So, the AAH arguments seems not so outrageous at least for half of our species?"
The human female body is adapted for sexual attractiveness. Why else do women have protruding breasts and buttocks? Lack of body hair is a good way of drawing attention to sex, especially with some of that limited hair in an intriguing triangle with the lower apex pointing to the site of maximum interest.
Their curves make them less, not more steamlined for movement through water. In terms of ability in water, males outperform females every time. No female olympic swimmer has come close to the equivalent males in either stamina or speed events. Men are better at breath hold diving also. Apart from the odd freak like the delectable Tanya Streeter, the records for depth and breath hold times are all held by men. Even Tanya's records are massively exceeded by the best male divers. Ama divers are female by tradition, not by physical superiority.
Fat is a good energy store. It costs less energy to maintain than an equivalent amount of energy in the form of muscle. This can help us get through lean times without starving. As anyone who has gone on a diet knows, the body responds to reduced calorie intake by consuming muscle first, before fat, unless you exercise a lot. Of course this trait would tend to reduce the ability to go and get more food, so it's a tradeoff. Perhaps man's technological advantage allowed him to survive hard times with less reliance on strength, shifting the advantage to more fat storage.
Also out of curiosity what is the adult size range that CFelegans and Iceaura are using for the aquatic mammal/Aquatic ape comparisons?
That might explain a lot. No, I'm sorry ...
(Hippos, not seals...)
That's kind of a strange request, 'cause that's not controversial at all in modern science. Science agrees, that humans have for some strange reason shed the fur and replaced it by skinfat for heat insulation. It's thoroughly dealt with in Frederic Wood Jones' "Man's Place among the Mammals" as early as 1919, and has been studied extensively ever since. In fact, Wood Jones' observation of "why humans, unlike all other land mammals, had fat attached to their skin", was one of the key notions that originally lead Alister Hardy to suspect that humans are aquatic primates. That this type of fat is blubber.
Link: Alister Hardy - Wikipedia, the free encyclopedia
When you use Google Scholar to search 'chimpanzee subcutaneous fat', the very first entry states:
Link: Selective Sweeps in the Human Genome: A Starting Point for Identifying Genetic Differences Between Modern Humans and ChimpanzeesOne long-noted basic anatomical difference between humans and chimpanzees is the human subcutaneous layer of fat which is
lacking in other primates.
Again, a strange request, 'cause that's not debated either. Use Google Scholar and search "fat insulation aquatic mammals".
You might as well be asking for credible references to why the Earth isn't flat, excuse me.
Yes, it is correct that many species of otter and seals have retained fur for insulation. But note, that these aquatic mammal species is adapted in temperate to polar climates, whereas tropical and subtropical aquatic mammals all adapt to shed the fur in full (and all humans are originally tropical mammals in any scenario, aquatic or not). This difference based on climate zones is particularly visible in sea lions, where a species like the Steller sea lion from the cold Bering Sea has fur (and skin fat), while its cousin the Californian sea lion in a subtropical belt is slick as a bottle. And in the case of otters, both small body size, temperate climate and recent aquatic adaptation may be factors as to why these species still has fur.
Compare that to a tropical aquatic like the hippo (which I suspect we exceed in aquatic ability when observing these freedivers or sea peoples), who is both naked and fat. Or to naked land dwellers like elephants and rhinos, which both is now suggested as having been aquatics in earlier evolutionary stages (this of course explaining why wildebeests only drink from rivers and lakes, while elephants has to bathe in 'em).
Link: Elephant - Wikipedia, the free encyclopedia
Here of course the follow up question is, that if contemporary zoology has no problem working with a scenario where a large, naked mammal like the elephant may be a past swimmer/wader without fearing 'academic execution by ridicule', why is it such 'pseudo-science' and 'Oh, no, not the Aquatic Ape hypothesis!' to suggest something quite similar with another African mammal, a primate, that just so happens to be ourselves?
And there in lies the rub. Because this debate is about us. Every time human science has made a leap forward in understanding Creation and especially our own place in it, we have a tendency to pee ourselves and aim the pitchforks at the discoverers. That is why the threat of torture of an Italian lens maker in his 70's is the greatest sin ever committed in the history of science. That is why a 19th century British naturalist is still being persecuted for his studies. That is why a German weatherman got ridiculed for fifty years by scholars who should've known better. And that is why a Welsh TV screenplay writer has been ridiculed for the last forty years by scholars who should know better. Scholars who betray their own scientific methods, because this pathetic little 'splash-splash' notion for some damned peculiar reason is an inconvenient truth!
I must say, that it leaves me quite depressed as to the scientific potential of the human race.
Last edited by CEngelbrecht; August 21st, 2011 at 08:47 AM. Reason: Spelling
Engel
You cannot compare hypothesizing about aquatic apes with Galileo and other luminaries.
The difference is the lack of evidence. The aquatic ape idea would get full credit if, and only if, the evidence was sound. It is not.
Show me fossils of our hypothetical aquatic ape in marine sediments, and I will take the idea seriously. The marine environment is the best place to form fossils, by far. If our ancestors had spend any significant amount of time puddling around in the sea, many would have died there, and been preserved. Yet not one fossil has been found in that environment. Compare this to the numerous pre-human fossils found in terrestrial and fresh water environments, along with the fossils of other land mammals.
Human hairlessness is easily explained in terms of known evolution. The human fat layer would devlop along with hairlessness, to provide a little thermal insulation after hair has gone. Nothing special about that.
The most special thing we know about humans and pre-humans is the use of technology. Homo habilis made stone tools by knapping, up to 3 million years ago. Homo erectus made better tools, and Homo sapiens carried technology to its now great heights. As I said before, we should be called Homo technologica, since well developed technology is the one thing that distinguishes our species, and our forebears from all other mammals. That technology is what we are adapted to.
Bipedalism to handle and carry tools and weapons. Hairlessness in response to the technologies of fire and clothing. Fat layer to supplement thermal insulation. Social togetherness, to enhance defense using spears and clubs as a group, and a large brain in response to the need for sophistication in working together, including language and communication. There is nothing about the aquatic ape hypothesis that is needed to explain human evolution.
still waiting for size range number on the AA being talked about.
I don't know what will be CEngel's and Iceaura's answer, but reasonably humans are in the size range of dolphins, manatees, and seals. Dolphins and manatees are out of question, but we see some interesting trends in the pinnipeds, as in CEngel's example of Steller's Sea Lion VS Californian Sea Lion, and my example of Polar Seals VS Monk Seals, that medium-sized mammals apparently have a need for fat but not fur in the tropical waters.
Maybe I haven't state clear what's "streamlined" -- A torpedo/rhombus shape, smooth surface curves, that allow water (or air) flows through smoothly and minimize eddy currents. Streamlined are many aquatic animals (dolphins and seals), vehicles (airplanes and submarines), even fast land mammals (leopards), and is also an appropriate adjective for human female's body. Not so perfect like sharks / dolphins / ichthyosaurs, but you can compare to our fellow apes and monkeys.
I see argument that women's big breasts and big buttocks make them un-streamlined, but come on... will you point to dolphin's pectoral fins, or Ferrari's side mirrors and wheels, and say that they're not streamlined? These are their non-dispensable functional parts, as long as these features are themselves streamlined or well covered, it's just fine.
CEngel, I couldn't say it any better.
Frankly, all counter-arguments to AAH are just fine, or any alternative explanations are welcomed. As long as AAH is still a bunch of hypotheses, they're subject to scrutiny and criticism, and we're ready to discard any of them if we finally got better explanations with proper evidence.
But what irritated me most is some of the biased reactions, and some people, I've to say, appear to "hate" AAH. Of course, as humans we're free to express preferences to a certain standpoint, like a political ideology or a religious belief. But in science, especially when we aim to examine a hypothesis using scientific method, we should ask ourselves, did our emotion affect our judgement? If someone "loves" an idea, he tend to see everything as supporting and bypass any contradiction (like my attitude towards AAH some years ago). If someone decided to "hate", he tends to persuade himself that it must be non-sense, that there is no evidence, even tempted to twist available evidence and well-accepted facts into doubtful questions to fulfill the prophesy.
CEngel's example of elephant is an excellent demonstration. When it's not emotion-laden, we're ready to accept surprising conclusions like a mammal can go back to the oceans and come back to the savannahs again. Even a decade ago, when solid evidence (isotopic data of teeth) was not available, a scientist who speculated on their aquatic ancestry based on naked skin, snorkel-like trunk, kidney morphology, swimming ability etc will not be ridiculed or deemed pseudo-science. But when it's all about human, the acceptability is just not the same.
This is one of those ironic threads that can only exist on popular science fora.
There is the popular notion that one can support or undermine the aquatic ape theory by discussing its merits or worse, one's own dogmatic preferences.
There is only one scientific way to support or destroy the aquatic ape theory. And that is to do actual research.
Since nobody here is doing that here (for obvious reasons) it is really funny/sad/ironic/entertaining (fill in your preference) to see so many having a vested interest in this topic, and to see so many people being absolutely sure of their own viewpoints.
One could start a topic on what kind of evidence would be needed to support the aquatic ape theory and how it could be gotten. This could actually be quite interesting. Although possibly it is also a minefield.
Otherwise what we are doing is just rehashing of known facts, speculations, and falsehoods with the effort of soothing one's own mind. A poll is probably the silliest thing you can do scientific wise, so hence my personal need to intervene.
A scientist has spoken. And it will go unnoticed as usual.
Which is very odd answer considering that the semi aquatic stage if it existed would have been when the semi-aquatic hominoid was less then to about 100 lbs in size and most likely smaller. This is based on the sizes of the oldest distinct bipedal fossils known, Orrorin tugenensis and Ardipithecus looking at the size increase overtime from the Miocene to the Pliocene. So you are comparing to mammals that are actually notably larger then the semi-aquatic Hominoid would have been. Thus you are comparing the semi-aquatic hominoid to taxa that minimally at least double its size.I don't know what will be CEngel's and Iceaura's answer, but reasonably humans are in the size range of dolphins, manatees, and seals. Dolphins and manatees are out of question, but we see some interesting trends in the pinnipeds, as in CEngel's example of Steller's Sea Lion VS Californian Sea Lion, and my example of Polar Seals VS Monk Seals, that medium-sized mammals apparently have a need for fat but not fur in the tropical waters.
The sea otter and giant river otter and African clawless otters are all within the size range that you should be looking at, and the giant and clawless otters are from the tropical regions where the aquatic stage would have occurred.
Chris,
In one of my previous posts (#69) I suggested that the lack of subcutaneous fat in non-human primates is a misconception that likely has its origins in F. Wood-Jones's "Man's place among the mammals". This was subsequently used by Hardy and a myth was born. Suggesting that I refer two these two authors for enlightenment is rather bizarre since this is where I suggested that the myth stems from. If you read the literature you'll see that this contentious claim is repeatedly made either without reference (because some consider it so well established and self-evident that it is basically a "given") or they reference Hardy or Wood-Jones (as in the paper you linked to); other references used for the claim can probably be traced back through others to Wood-Jones too. You'll notice too that all papers that state this claim didn't actually examine a single primate themselves. There is not one single data point. No measurement. No direct observation. All we have is a repeated assertion - usually in a review that is not specifically about subcutaneous fat directly.
When I used your suggested search terms I found lots of results of work discussing subcutaneous fat in chimps - actual measurements and real data. Perhaps you could explain the following:
CA Shively, TB Clarkson, LC Miller and KW Weingand (1987)
Body fat distribution as a risk factor for coronary artery atherosclerosis in female cynomolgus monkeys
1987, 7:226-231 Arterioscler Thromb Vasc Biol
Douglas S. Lewis et al (1986)
Preweaning Food Intake Influences the Adiposity of Young Adult Baboons
J. Clin. Invest. Volume 78, pp 899-905
Here we have two papers making direct observations and measurements of subcutaneous fat in non-human primates. They are observing it in live non-human primates. They have dead non-human primates on the dissection table. They are mapping the distribution of subcutaneous fat. Measuring it's thickness. Real data. Actual science. Can you see that? So no, my request for evidence to back up your claim is not a strange one at all for the science does not agree with the AAH claim in the slightest.
When I use Google Scholar I see hundreds of papers on the properties of non-human primate subcutaneous fat. I'd challenge anybody reading this thread to conduct their own searches and report back. All I'd ask is that you avoid AAH hypotheses papers (which flood Google Scholar) and reviews and stick to direct expermental reports or books specifically about primate and/or mammalian skin.
The rest of your post is equally unfounded in fact and myth. Neither did it actually address the request I made. I've not the time at the moment to go through it except to point at that the role of fat as an insulator is not at all clear. Things like diet, local and seasonal food availability, migratory habits and bunch of other things seem to be far more important. It's simply silly to randomly pluck two species and compare them. Let us see the data.
Last edited by Zwirko; August 14th, 2011 at 12:42 AM.
I beg your pardon, but I think you are reading these works wrong, and also there's a somewhat misguided use of language by some scholars when studying fat. You refer to works that eg. studied cardiovascular illnesses connected to obesity in other primates, which is designed to make a prediction about a similar effect in humans. You can't use these works to denounce that humans have insular skinfat instead of fur, because these tests made use of drawing visceral adipose tissue (body fat energy reserve) from the belly of these other primates. For some reason, this is called 'subcutaneous adipose tissue' in some works, but this visceral fat is not the type of insular fat in the human skin, eg. in the limbs, that this debate is referring to.
Consider this article: http://en.wikipedia.org/wiki/Visceral_fat
Here you find an image caption called 'subcutaneous adipose tissue on a male' [human]. However, the image clearly show a visceral fat depot in a man's belly, a type of depot that all primates share. Technically, this visceral tissue is indeed 'subcutaneous' (Latin for 'under skin', in Greek called 'hypodermis'), but it's a lingual misunderstanding to compare this with the insular skinfat only found in humans among the primates.
I must reiterate, that humans for some evolutionary cause shed the fur and instead developed subskin fat for insulation. This is still not a controversial claim. At all.
I will agree that it is possible, that elder ideas in science may be outdated and based on only partial data. But that might also include the assumption that humans are purely terrestrial.
Play the mind game, that a tropical jungle ape is forced to adapt to a coastal habitat, swimming and wading for food and protection, and consider how that being would turn out both physically and mentally. I put it to you, that it would end up quite similar to what we are today. Naked, habitual bipedal, habitual bathing, talking, singing, with hooded nostrils, not tearing when giving babies in the water's edge, capable of reaching phenomenal depths when breath hold diving, and drawn to 'beautiful, romantic' tropical beaches.
What's remarkable to me is how many of those characteristics you're attributing to our species are almost entirely cultural.Naked, habitual bipedal, habitual bathing, talking, singing, with hooded nostrils, not tearing when giving babies in the water's edge, capable of reaching phenomenal depths when breath hold diving, and drawn to 'beautiful, romantic' tropical beaches.
especially when they would have been the size of a larger otter species and that no ape/homonid fossils are found in middle to late Miocene marine strata.
Excuse me, but this only confirm to me, that AAH-oponents will not lower themselves to read the actual source texts. If you'd glance through Hardy's original text from 1960, you'd find that what he proposed was a coastal ape, not a sea ape. That is all it has ever been. Not a dolphin ape, but a beach ape. Not a marine primate, but a coastal primate. Coastal! Coastal, coastal, coastal. Did I mention that he proposed a coastal ape, not a sea ape?
We would not find this aquatic ape in marine sediments, but in coastal sediments. Either out to sea, rivers or lakes. And I beg your pardon, but that is EXACTLY where we have found many of the key specimens labeled to the human fossil archive. Specimens like the Taung Child, like Lucy, like Ardi, like Toumaļ. Like the entire species of Oreopithecus, a potential first aquatic ape of human evolution.
It leaves me furious to see also experienced scholars betray their own fields by insisting that Hardy suggested a form of primate which is easy to refute, but which Hardy never proposed. Because this idea has to be crazy by any mean necessary. It is preposterous to claim that there is no evidence for the aquatic ape in this fashion. And in that sense, yes, I do believe we can compare to Galileo. The refutation of the aquatic ape stems too much from social dominanse behavior, not science.
I put it to you, that the proposed evidence exists, it exists in abundance and is screaming at us from the drawers of the faculties. But no evidence pops up untill the coppers get off their arse and go look for it.
Last edited by CEngelbrecht; August 15th, 2011 at 11:09 AM.
Granted, some on that list may be a cultural whim in some random generation, primarily those pertaining to human behavior. But the ones pertaining to human physiognomy (naked, bipedal, hooded nose, not tearing in water births) could only with difficulty be claimed to be caused by culture, especially when applying parsimony.
The most likely place to find fossils of a coastal dwelling ape are strata that preserve nearshore marine sediments, as this is the area that will have high deposition rates and so preserve the carcasses of animals that die in the tidal zone.
Chris, you're going to extraordinary lengths to avoid facing the facts. Read both papers again please. Pay particular attention to the methods and results sections. What you wrote in your reply is not true.
One thing I've noticed is that of those people who find the AAH appealing and have a bit of savvy about them, many don't use the no sub fat argument. They tend to focus on the thickness or distribution angle. They do this because it is not possible to effectively argue there is no sub fat because it is a basic feature of mammalian skin.
As a person who lives on the coast, and goes for numerous walks along our lovely beaches, let me offer this observation. There is one animal that shows a much more powerful attraction to the sea than humans. I am talking of dogs.
Right now, it is winter here in the southern hemisphere, and the sea is bloody cold! Yet when people take their dogs for walks on the beach they tear into the water with enthusiastic abandon, and evident great pleasure into the sea to fully immerse themselves in spite of the cold.
I would hereby like to propose on the basis of this single observation that the evolution of dogs involves an aquatic stage. I call it the ACE hypothesis (aquatic canine evolution). There. That ACE'd the competition!
Well then, I suppose, your Canis aquaticus should have splashed, or even jumped into the beautiful water and enjoy it. Then I wonder, with a little more effort, can he dive a little bit deeper, say a few or dozens of meters, because even his fellow humans (a terrestrial species) can do it. Or when he swims with his perfect doggie style, he should have evolved to allow his front legs move circularly or his spine sinusoidally, as these could help his speed a little bit. I won't insist his pregnant mate to deliver her pups under water... that will make them drown, but he and his family should find the abundant raw seafood a delicacy so not to starve at the coast.
In any way, he will need badly a few mediocre aquatic adaptations so to live up to his name of the aquatic canine!
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