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| Pong |
 Posted: Tue Apr 22, 2008 10:56 pm Post subject: Aquatic ape |
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I read about this theory in the 80's: Humans survived some drought periods living around shorelines, wading and even swimming in water, where there was food. This is supposed to account for changes in posture, hairlessness, tool use (chipping oysters), body fat, even boobs.
Where'd it go? Opinions? |
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| marnixR |
| Posted: Tue Apr 22, 2008 11:39 pm Post subject: |
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Forum Cosmic Wizard
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this topic has been discussed on this forum about a year ago :
Aquatic Ape Theory
it would appear that, although at first glance an elegant alternative explanation, it has been refuted, even if the same old arguments resurface from time to time
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| Pong |
| Posted: Wed Apr 23, 2008 1:30 am Post subject: |
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I don't want to necropost in that, but thanks. Did read it.
Looks to me like both sides were uncompromising, where they could have synthesized. It's not like an either/or proposition. Is it?
For example:
I can sweat profusely in hot weather. Does this suggest all my ancestors came from always hot climates? No.
Circulation in my extremities shuts down in extreme cold, to conserve critical heat. Does this suggest all my ancestors came from always cold climates? No.
I'm an assembly of adaptations. Maybe some of my ancestors adapted somewhat to an environmental challenge, even one visited occasionally. So I'm fairly comfortable and mobile in a tree. That doesn't mean my ancestors climbed trees more often than they absolutely had to! An occasional test is enough. Consider the hand. It's multi-purpose. We do different things with it. So with the entire body. Why claim the body, widely adapted to meet a range of challenges, didn't also adapt to water?
I think I have a bias to aquatic ape theory because of all the time I spend on shorelines with my son, prying delicacies off the rocks, corralling fish into tide pools, etc. We love it. There's just so much food in the intertidal zone only smart scavengers can get. I see those clever raccoons doing same, and think this a perfect environment to develop ingenuity and tools (which we do, spontaneously). Yes we wade down to grab tempting things. Unfortunately Western Canada's waters are a bit cold for prolonged exposure, and I won't be caught swimming in them! |
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| marnixR |
| Posted: Wed Apr 23, 2008 4:01 am Post subject: |
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Forum Cosmic Wizard
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my main problem with the aquatic ape theory is that most of it depends on soft anatomy, and as such it's very hard to determine WHEN certain of our adaptations happened
if you don't know when something happened, not even to the nearest million years, then it becomes very hard to relate changes to outside factors causing these changes
however, i WOULD be interested in finding out whether there's any remains in the Danakil alps that might throw some light on the issue
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| Pong |
| Posted: Wed Apr 23, 2008 4:35 pm Post subject: |
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I don't know that fossils or even technologies out of one region would look any different than another, if the populations were still mixing.
See what I'm saying? You can have adaptation throughout a population, when only one end is... dipped, shall we say... into novel conditions. If the changed nose shape costs a savanna dweller nothing, what's stopping that from spreading through the whole population?
AAT failed because we thought shoreline and savanna populations must be exclusive.
Consider the common North American raccoon. In my neck of the woods, coast Natives call her "washing hands". The name describes the typical activity of feeling around underwater, upturning rocks, their chins held high as they wade along the coastline... raccoons are very effective tidal zone scavengers, with their nimble, sensitive paws. So we have family groups that basically live off the sea. Raccoons also live inland. They always have. Same species! Would we say a raccoon born on the prairie is partially adapted to the water? Why not? |
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| marnixR |
| Posted: Wed Apr 23, 2008 11:36 pm Post subject: |
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Forum Cosmic Wizard
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the reason why i picked out the Danakil alps is that this is one of the few predictions made in one of Elaine Morgan's books that can be checked out - if fossils of the right age turn up in the right spot then at least there would be some concrete evidence that matches the predicted time and space and could lead to further investigations
although, your raccoon story shows that behavioural adaptations can initially happen without noticeable differences of the skeleton, so not sure whether finding fossils there really would give us the necessary clues
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| Pong |
| Posted: Thu Apr 24, 2008 1:50 am Post subject: |
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It seems to me unlikely we would find specialization. Why Morgan had to claim we only lived off water bodies, rivers, etc. in this particular isolated place and time... beyond me. Kinda set a trap for the theory.
She actually claims an "intervening stage" "from trees to land". As if we can't thrive and adapt in many conditions simultaneously, throughout our varied range.
On the other hand, savanna proponents likely feel "you're in the trees or you're not, ever". |
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| marnixR |
| Posted: Thu Apr 24, 2008 3:44 am Post subject: |
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if the case of Ardipithecus has taught us anything, it's that bipedalism had already developed in a forest environment
+ A.afarensis still has skeletal clues that it was comfortable both on the ground and in the trees
imo bipedalism just opened up options when the forest environment retreated, unlike our chimp relatives who were forced to stay in the forests
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| Ophiolite |
| Posted: Thu Apr 24, 2008 7:41 am Post subject: |
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| Pong wrote: |
| On the other hand, savanna proponents likely feel "you're in the trees or you're not, ever". |
Savanna theory is dead. Mosaic theory replaced it. Morgan suggested periodic flooding (which is proven) of tree habitat would foster the move to a semi-aquatic existence.
Marnix's point about the difficulty with soft tissue issues may be resolved through detailed gene analysis. (I think.  )
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| i_feel_tiredsleepy |
| Posted: Thu Apr 24, 2008 10:40 am Post subject: |
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| Pong wrote: |
Consider the common North American raccoon. In my neck of the woods, coast Natives call her "washing hands". The name describes the typical activity of feeling around underwater, upturning rocks, their chins held high as they wade along the coastline... raccoons are very effective tidal zone scavengers, with their nimble, sensitive paws. So we have family groups that basically live off the sea. Raccoons also live inland. They always have. Same species! Would we say a raccoon born on the prairie is partially adapted to the water? Why not? |
A little off topic, but the raccoon is not adapted to marine water. I think the washing hand thing comes from their dousing behavior, which they do inland in fresh water also. These are forest adapted animals that have gripping front paws for climbing trees, these front paws also made them highly adaptable to a lot of habitats because they could then manipulate a lot of objects other animals can't. So they can turn over rocks and catch fish, after they became adapted to catching fresh water fish it isn't much of a stretch to go after shellfish in tidal regions.
They're also annoyingly good at opening trash cans >.> |
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| Pong |
| Posted: Thu Apr 24, 2008 12:51 pm Post subject: |
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| i_feel_tiredsleepy wrote: |
| These are forest adapted animals that have gripping front paws for climbing trees |
I can't see why the adaptation must have one cause though, as if the animal only climbed trees. Did it constantly grip tree limbs, never employing those same paws for other tasks?
Consider cat claws. One argues the claws were developed for scaling sheer surfaces (this also allows cats to pin prey). Another argues the claws were developed for pinning prey (this also allows cats to scale trees). Who's wrong?
Consider a chimpanzee's hands. What are they for, specifically? 
Can bipedalism admit multiple, simultaneous advantages?
If so, then it's no stretch to imagine one sister using her improved bipedalism to gather bundles in a forest; while at exactly the same time a second sister uses it to scan a horizon; while even farther down the valley our third sister forages the river, bipedally. |
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| i_feel_tiredsleepy |
| Posted: Thu Apr 24, 2008 2:38 pm Post subject: |
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Location: Montreal
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| Pong wrote: |
| i_feel_tiredsleepy wrote: |
| These are forest adapted animals that have gripping front paws for climbing trees |
I can't see why the adaptation must have one cause though, as if the animal only climbed trees. Did it constantly grip tree limbs, never employing those same paws for other tasks?
Consider cat claws. One argues the claws were developed for scaling sheer surfaces (this also allows cats to pin prey). Another argues the claws were developed for pinning prey (this also allows cats to scale trees). Who's wrong?
Consider a chimpanzee's hands. What are they for, specifically?
Can bipedalism admit multiple, simultaneous advantages?
If so, then it's no stretch to imagine one sister using her improved bipedalism to gather bundles in a forest; while at exactly the same time a second sister uses it to scan a horizon; while even farther down the valley our third sister forages the river, bipedally. |
The ability to climb trees is the feature that would be selected for most though since it would dramatically increase survival. It indeed does help them in gathering food, and which came first isn't really important, but raccoons are by and far descidious forest dwellers, and the adaptation to climb trees is very common with descidious mammals. |
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| Pong |
| Posted: Thu Apr 24, 2008 11:21 pm Post subject: |
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| i_feel_tiredsleepy wrote: |
| the adaptation to climb trees is very common with descidious mammals. |
Yeah, I yet appreciate it when I have some pruning to do... cherry trees too. 
But I want to go back to an earlier question. If we have a population, occupying ranges A & B, each range adequate, yet range B offers some sweet exploit... exploit like, break the nut, you win a prize... how does the population adapt to that? Suppose that gaining a bit more dexterity (to break the nut) is highly advantageous to B-dwellers, and costs A-dwellers nothing. A takes it on, no?
I'm looking for examples.  Sure with modern humans we have lots of traits associated with a particular region, which we may not live in. The traits cost nothing, so they spread (e.g. brown eyes). Better "real world" examples?
Best I can think of is the dungeness crab, named for Dungeness Spit, a sandbar where it's obscenely abundant. This crab is well adapted to a muddy bottom (e.g. at Dungeness), which it buries into when threatened. The funny thing is, the species ranges from Aleutian Islands to California - much of its habitat offers no sandy or muddy bottom at all. Apparently, the skeletal characteristics that help dungeness bury (if possible) don't cost the general population much. So they all share the adaptation, even where irrelevant. |
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| marnixR |
| Posted: Thu Apr 24, 2008 11:34 pm Post subject: |
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Forum Cosmic Wizard
Joined: 10 Apr 2007
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Location: Cardiff, Wales
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| Pong wrote: |
| But I want to go back to an earlier question. If we have a population, occupying ranges A & B, each range adequate, yet range B offers some sweet exploit... exploit like, break the nut, you win a prize... how does the population adapt to that? Suppose that gaining a bit more dexterity (to break the nut) is highly advantageous to B-dwellers, and costs A-dwellers nothing. A takes it on, no? |
survival of a species does usually not just depend on one trick (although if it's one that means the difference between life and death, then it might do) : it's not just a matter of finding sufficient food, but what is the reproduction pattern, how heavy is the predation, how prone is the environment to fluctuations etc.
also, do i see a hint of lamarckism in your reasoning (it's good to be able to crack a nut, so the first one to develop the dexterity to do so will flourish) ?
in my experience i see that species develop a certain trait through random variation, which then gets co-opted into other usages, and depending on the needs of the organism in its environment can become a useful adaptation
SJ Gould used the word exaptation for this type of co-opting of existing traits, and i think it's a far more important phenomenon than i usually see it being given credit for
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| Pong |
| Posted: Fri Apr 25, 2008 1:05 am Post subject: |
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Wanna take a crack at the question?
If it costs nothing, to any member of a species occupying both environments A & B, will those occupying A take adaptations out of B?
For hypothetical example. Some mountain goats. A western population, an eastern population, same species, they do mix though an individual wouldn't possibly travel the whole range. The westerners suffer no predation and are limited only by scarcity of food. The easterners are harassed by cougars which prey mainly on deer of the adjacent forest. These eastern goats would do well to camouflage with a reddish shrub particular to their range. Colouration makes little difference to the western goats. Do the western goats turn rusty too? |
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