Ohh, lets get really taxing now.
Do we know of any intermediary fossils?
Are fossils the only evidence for evolution or indeed are they the strongest evidence for evolution?
|
Ohh, lets get really taxing now.
Do we know of any intermediary fossils?
Are fossils the only evidence for evolution or indeed are they the strongest evidence for evolution?
Two seconds on Google would answer this question: List of transitional fossils - Wikipedia, the free encyclopedia
They are NOT the only evidence for evolution, but they are strong (and oft denied) evidence.
Evolution is a well established fact. HOW evolution happens is what the "theory" part is about.
What is the evidence for evolution?
What is the evidence for evolution?
Lines of evidence: The science of evolution
Lines of evidence: The science of evolution
Apes and man links. Do we believe there is an ancesteral one, or, has Darwin been misquoted?
I believe the current evidence is that our lineage and that of Pan speciated from the ancestors of gorillas ~10 million years ago. Someone else may have to fact check that, though.
I recently gave you a list of one for the dinosaur to bird transition. Similar ones exist for land animal to whale evolution, equines, pinnipeds, humans etc.
Just one of many lines of evidence.Are fossils the only evidence for evolution or indeed are they the strongest evidence for evolution?
The fossil evidence probably isn't even the strongest anymore...genetic evidence is even more compelling.
For a quite simplified explanation for the scope of evidence:
http://www.astro.umd.edu/~miller/tea...9/slides08.pdf
I think Selective Breeding/Artificial Selection a nice example of evolution in progress. E.g. Dog breeding.
Natural Selection is simply the default process that occurs when, us humans, aren't interfering with nature. Before humans, natural selection has been running amok for millions of years.
I am a fan of talkorigins myself. Here is their page on intermediate fossils: CC200: Transitional fossils
They have an index of claims. It's quite useful.
Fossils are far from being the strongest evidence for evolution. Evolution depends on simple "barn yard" level observations. 1) Like begets like, cats have kittens, dogs have puppies, in short ofspring look like their parents. 2) Process #1 is not perfect. Feaks happen. 3) not every individual has equal chances of becoming a parent. If something about you prevents you from becoming a parent then the next generation will not have any individuals with exactly your genetic material. You can only pass on your genetic material if you have offspring.
Not now - they're on different continents Maybe a long time ago when some tiger species were in the same areas as some lion species.There was a tiger and a lion that were crossed (liger) but does this happen in the wild?
I'm sure this sort of thing can happen, though it is unlikely the offspring will be fertile if they are different species (mule is a good example).
Hannah have a look at "ring species", e.g. here:Ring species - Wikipedia, the free encyclopedia
These are populations of closely related creatures in which the closeness (or distance) in relationship can be expressed by plotting them on a ring (genetically closest next to each other, most distantly related, on opposite sides of the ring). There are several examples of groups like this which can interbreed with near relatives but cannot with the more distant ones on the other side of the ring.
With these, what you effectively looking at is a species caught in the very act of splitting into several.
Im not a Palaeontologist but here are some of my thoughts:
Whats the % of the surface of the earth that was thoroughly dug up and examined to search for fossils?
10%? 1%? 0.1%? 0.01%? 0.001%?
Lets say you dont know where chimpanzees live, you take a pin, close your eyes, roll the globe and randomly pin a location, what are the odds that you will find chimpanzees in the specific location you pick?
In addition, if by a stroke of luck you do find chimps, you might say hey heres where the apes are, and look in the same region, and find chimps as opposed to Orang-outangs (not sure of spelling), and say in 2014 there were chimps and we found no evidence of other Apes on earth (although we did not look everywhere, so because you havent found Orang-Outangs, Gorillas or Lemurians(Madagascar?) where you looked it doesnt mean they do not exist).
Last edited by icewendigo; March 13th, 2014 at 11:58 AM.
You have the bulk of it, yes. Replication with variation, and selection by the environment. These are the key concepts.
Perhaps, but not likely. However, with more social species, yes, absolutely. We Homo Sapiens Sapiens have a lot of Neanderthal DNA, and we could almost certainly make babies with Homo Erectus and almost certainly did. We might be able even to make mules with gorillas or chimanzees. Certainly H. S. S. can mate with Denisovans and Floresiensis and all the others, if we could with H. Erectus. Men are dogs; they'll poke anything.![]()
If evolution is a continual process, aren't just all fossils transitional? It would all depend on what was first classified as a given species.
And if that could be done with the complete fossil record of H. Sapiens (or of any species) it would be a really amusing slide show. It's just that I find the question a bit misleading because it seems to imply that the better-known species (fossil or extant) are somehow milestones or goals.
Not that the OP intended it that way but it's like talking about the "missing link".
Some patterns are very successful and last a long time, through multiple species. Turtles, crocodiles, and birds are good examples. So are felines. So are domesticated primates.
OTOH all of us are amateurs compared to sharks. They're almost as old as bacteria. Sharks are very successful. The very largest sharks don't eat meat; they are filter feeders like the baleen whales. These are called "whale sharks." Sharks are over 300 million years old.
Good point. The notion of "missing links", which is beloved of newspapermen etc, tacitly implies the fossil record is a jigsaw that is essentially complete, apart from a handful of "missing" pieces. But of course it cannot be.
A few moments reflection on how fossils are deposited and then discovered hundreds of millions of years later, in spite of all the intervening geological processes of the Earth's crust, should make one realise that only a tiny fraction of the lifeforms that have existed can possibly be known to us. Which means the number of "missing" pieces of the jigsaw must vastly outnumber the pieces we have been lucky enough to find. And, as you rightly say, those we have found have no special status , other than that of having been found by us. So they are just as "transitional" as anything else, including any creature alive today.
The short answer is yes, as well a birds, reptiles etc.
--
Here's a fun blog about the subject in more detail. I normally avoid blogs, but this one looks pretty good at first glance and rather well referenced--I hope I'm right as I read more.
http://pigeonchess.com/2012/05/31/gi...ny-other-name/
Last edited by Lynx_Fox; March 27th, 2014 at 06:56 PM.
Last edited by Paleoichneum; March 28th, 2014 at 10:39 AM. Reason: spelling
I've now read the article and would like to pick up on the above. The author said:
"So that leaves us with the semantic objection to the informal use of the term gill slits to refer to these structures, which is a bit like getting worked up over calling the human coccyx a ‘tailbone’ because it never functions as a proper tail in humans."
"Creationists are fond of repeating that in amniotes, “gill slits” are not only not gills, they’re not even slits. And they are partly correct if by “slit” one means an unobstructed opening from the outside of the neck region to the inside the of throat of mammal embryos. That is, they are technically correct as far as normal mammal development goes, however this is not the case with all non-”fish” vertebrates, nor is it always the case with mammals including humans."
So would it be strictly accurate to say that there are almost always 'slits' in the developing embryo? The author cites mutations, but leaving that aside, and ignoring the analogies following the first quote, the author would otherwise seem to agree that there are no 'slits' in the sense of unobstructed openings. Would this be a reasonable interpretation of what was presented?
Transitional types ? A better question is: what form ISN'T transitional ? DNA indicates all are. As well as simple comparative anatomy. Creationist are priests
in science clothing. Nothing more.
Yes it is very accurate to say the for a small amount of time the mammals do have pharyngeal arches (correct anatomical term). They are one of the four defining characters that unite the Phylum Chordata, along with a hollow dorsal nerve cord, a notochord, and a muscular post anal tail. All are seen during embryonic development.
The confusion that seems to be happening is that the author is using the wrong term, slits, rather then the correct term, arches. They develop into gill slits in some chordates, into neck and ear bones in other chordates.
Thanks for the replies.
I am still a bit confused, Paleoichneum. This post suggested there were slits:
This also suggested slits (unless Flick was calling me a mutant):
Then this post says the author is using the wrong term - but you used the same term - 'slits' - in the first response you made:
Flick is categorical in that me as an embryo had unobstructed openings in the area referred to as 'arches', whereas you are not quite so equivocal. The author, you say, is using the wrong term, slits - I don't understand how that would be wrong if that is what they are.
Yes, but the word "slits" is misleading. You had pharyngeal arches.
Last edited by Flick Montana; March 28th, 2014 at 04:25 PM.
Slits is an inaccurate alternative name for the Pharyngeal arches.
Maybe a picture will help:
You had these. Whatever you want to call them is fine.
But it's agreed that I didn't have slits, right? Just to be sure before I carry on.
We had structures with spaces in-between them, that have been called both. the tissue portion is the arch, the space between the slit. period
Paleo basically said it. There ARE slits, but defining the slits as the structures isn't quite appropriate because they are just the gap between the important structures. If you have two objects which abut one another, there is a space between them which could be named, but it isn't really focusing on what is important.
I get this ominous feeling that you're going to try to make some kind of profound point based upon some silly semantics.
So these slits you talk about - do you agree with the author that they are 'unobstructed openings from the outside of the neck region to the inside of the throat of mammal embryos'?:
"Creationists are fond of repeating that in amniotes, “gill slits” are not only not gills, they’re not even slits. And they are partly correct if by “slit” one means an unobstructed opening from the outside of the neck region to the inside the of throat of mammal embryos. That is, they are technically correct as far as normal mammal development goes, however this is not the case with all non-”fish” vertebrates, nor is it always the case with mammals including humans."
This was where I started, and as your description seems to describe folds, rather than any opening to the throat, I am still trying to establish the existence of 'slits' - or not. The author does appear to be saying there usually are no slits. Therefore when it is said that there are slits, that is a contradiction to the comments made by the article writer, as far as I can tell.
As to why it's important, well, someone thought fit to write about it, illustrate it, publish it, have it linked to on a forum etc. Why would not investigation of the assertions made not be a natural and compelling thing to do? And I have only pursued it as I thought the answers given were contradictory and unclear. This isn't a criticism, as I appreciate the feedback given.
What is important is whether the mention of pharyngeal 'slits' is an accurate description or just a convenient tag to use. I believe the latter to be true and the former to be false from what I have understood so far. Also bear in mind that in answer to the question as to whether or not human embryos have fish-like gills, Lynn Fox answered 'yes'. As she then introduced evidence to support this assertion I looked at the evidence in that which mentioned 'slits' - which would support Lynn's assertions or not. Had the evidence mentioned arches there would have been no argument. But as the evidence was presented in support of fish-like gills in embryos I then have to see if that's what they are. The further evidence suggested not.
Yes.
You are arguing from a semantic position. Pharyngeal arches and the associated slits between them are found in All members of Phylum Chordata at some point in there development. From Humans to Lancelets and Tunicates.
If you are so concerned, then talk simply about the arches themselves and ignore the spaces between them.
Embryonic studies and genetic studies, along with evolutionary biology in general show there is no question about the presence of them in amniotes. Three members comments here does not doubt create.
As in 'The meaning or the interpretation of a word, sentence, or other language form'? I am not sure how a discussion about whether or not human embryos have fish-like gills can be had without interpreting what that phrase means. The inaccuracy of the view that human embryos have fish-like gills is supported by what the Blog article said, as far as I can tell, so if the description is regarded as wrong by the authority cited then the assertion falls down. I would be interested to hear what Lynn has to say in response to this.
As i have said a number of times, biology shows we do NOT have fish like gills. We have pharygeal arches and associated slits. They are NOT gills in humans or in fish until later in development, and only gills in some taxa not all. Do you understand during embryonic development they are neither gills or neck/ear bones?
This is what Lynx said:
He didn't say specifically that humans had fish-like gills, he simply offered an abbreviated response to your question. If asked to revise his statement, I'm sure he would clarify that what we have during our embryo stage are neither fish-like nor actually gills.
Stop arguing semantics. It's not important.
Sorry Lynx - misread you username. Thanks Flick and P for the correction.
You are the one doing that.
Lynx agreed that a proposition was true, Paleoichneum said it was not. Arguing semantics is not what the assertion of a perception of completely opposite statements being made is. It is pointing out that both statements cannot be true and that therefore one of them is wrong. A revision of one or both of the opposing views will obviously lead to an alteration of the perceived merits of them. We know that the two assertions are mutually exclusive so one must be false at the moment and that's all we have to rely on in the absence of revision.
He asked a personal question as opposed to one about the stance I had taken - thus fulfilling the definition you suggested I seek (below). So I think his response is very close rather than nowhere close. I need no knowledge of biology to recognise when two people quite clearly and unequivocally say the exact opposite to each other. Do I have to show a resume before pointing out the blatantly obvious?
ad hominem
ad ˈhɒmɪnɛm/
adverb & adjective
adverb: ad hominem; adjective: ad hominem
- 1.
relating to or associated with a particular person.
"the office was created ad hominem for Fenton"
- 2.
(of an argument or reaction) directed against a person rather than the position they are maintaining
The question is relevant so I know what level of detail you will understand while we have this discussion. It has nothing to do with attacking you, and you should assume good faith rather then attacking.
Seriously you should understand what Ad hominem is all about before you use it or accuse people of it. It is a converse of an appeal to authority. (you can look that up as well)
Ask yourself if the reason given to refute your argument supported by reason and logic--only if it isn't can you call it an Ad hominem.
If he had, for example said something akin to a mistake you had made about another topic....say physics, than it would have been an ad hominem. Or if you'd said onetime that you'd failed your BAR exam and he used that to claim you were a dumb ass and opinion about biology shouldn't be taken seriously...that would be a ad hominem.
In this example by your simple questions about evolution and transitional fossils, it is rather obvious you have hardly any knowledge about biology. By logic his question was directly related to the topic and quite reasonable. I assumed you didn't have a high level because of your very simple line of questioning. You got the term from the slide show, which was using a simplified language for laymen. Several of us answered the question and told you it was an alternative name with links to more complete explanations. Much like you might use a common name for someone who doesn't know anatomy...such as "heart" while a doctor might call it a cardiac muscle.
If you want to play childish semantics games we can all play and avoid simple common names--the result would probably be Homo sapiens sapiens never learn and cannot join in the conversation--both of which would be bad for the forum.
In this case you've now learned two words for the same thing as well as how it supports and is consistent with evolution. That's a good thing. Don't take confusion personally--most of us are ignorant about most things--that's just the way it has been since about 1500 CE or so.
Attacking? I was just asking. I assumed nothing other than a failure to appreciate that you and Lynx are saying the complete opposite to each other. The question in hand requires no input from me as to my level of biology. You were asking me an irrelevant question and I was enquiring why. My level of detail of understanding has no bearing on my ability to understand when two people are expressing completely different views and your question therefore seemed an odd one to ask in the circumstances. Hence why I wondered why you were asking.
So the conclusion is that human embryos have fish-like gills and that human embryos do not have fish-like gills. Thanks for clearing that up for me.
The REAL conclusion is that Lynx kept his response to your question at what he believed was an appropriate level. He did not correct the poor term choice because he would probably have to explain what "pharyngeal" meant or why gills and slits and arches are all used to describe the same feature.
I might actually agree that Lynx should have been more clear in agreeing with what you said, but it is in no way realistic to expect the guy could have known you would turn his brevity into a page-long semantic tirade to which you assign a great deal more importance and relevance than is worthy.
Maybe this will help (I suspect not): Do humans have fish-like gills as embryos?
Short answer: Yes.
Long answer: Sort of, but the term "fish-like" is merely a descriptor for someone unfamiliar with the structure to relate it to something they may have seen. It should not be taken literally. The term "gills" should be treated the same way. The function of the human embryonic "gills" is not the same as in a fish. These are not breathing structures. However, they do develop into important parts of the face and neck (as seen in the picture above) and can be associated with the same general area of the human form as gills are with fish.
The important point to take away from this is that there are many misnomers in generalized scientific terminology. Ladybugs are not bugs. Thus, you could find numerous scientific and general publications which contradict one another with both the scientific name and the one the general population uses. This does not bring into question the evolution of insects or the existence of Ladybugs.
You are taking semantics to a whole new level of absurd and it's making you look bad.
No, the conclusion is that human embryos have pharyngeal arches, with associated slits between, that sometimes get misidentified in lay publications as gill slits.
You need to understand that the publication you are looking at is highly simplified for they layperson, and NOT a biologically perfect explanation.
You claim a "quest for clarity", but things have now been clarified and you're still on your tirade. It's time to accept the answers which have been provided and move on.
So the general public are being misled, is my conclusion. And similar evidence is presented on here - also misleading the readers. If gill-slits are not there (as per the article quoted in support of gill-slits being there) then why mention them in the first place? It's a viewpoint which deserves no place in any publication if it's not true. The first diagram said 'slits', not 'arches', so I asked for clarification - which came back as verification of 'gills', which was then contradicted by the evidence presented in the article.
Had I not questioned the purported presence of fish-gills or slits the impression would have been left that human embryos have fish-like gills, as that was what was said and what the evidence presented was supposed to verify. But due to my persistence we now have a situation where that view is found to be invalid. I would have thought this was a satisfactory result.
No, the general public just doesn't seem to invest the brain cells into actually looking up the scientific description of these things. If you believe a Ladybug is a bug, that's your fault. The information is out there which corrects the misnomer. The same is true of gill-slits/pharyngeal arches.
OK then, so let's move on to the next slide in the presentation...
Which is?
Is it going to be about intermediary fossils or should it be a new topic?
I just skimmed through the blog he posted, too. You might be well-served to check it out. Like Lynx said, I'm not a fan of blogs for the most part, but that one seems to have some good thought put into it. It actually would have answered, in a great deal more detail, the question you posed earlier about "gill-slits".
Sammoot- No, the general public is not being misled in any way. The information is being given at the average level of biology understanding. More biologically exact and there becomes a knowledge gap that means no understanding happens. This is exemplified by the importance being assigned to the name rather then acknowledgement of the biology of the feature itself.Do you understand at this point what the structure is? And I don't mean what the name used is but the function of the feature itself.
Well, I thought I was right in thinking you had read the referenced article before you spent two days arguing about the facts presented in it, so being right in that instance could hardly be characterised as 'nice'.
But as you suggested, we should move on. Though please enjoy having the last word if you must.
To my knowledge, I never argued a single fact about the article with you. All we did was go over (and over and over) why misnomers plague science aimed as the masses.
I'm not trying to get the last word. I'm trying to see if you understand that there is no difference between "fish-like gill slits", a poor term created to evoke a visual in a layperson, and pharyngeal arches, the term to which one would expect someone with more knowledge in the subject to refer.
I mainly want to clarify this point because I feel like it sets the tone for further discussion. If this is how the rest of your questions are going to progress, I will probably take a much less active role in participating. While I like to share my knowledge and I get a great deal of satisfaction from helping people understand the few topics about which I am knowledgeable, I do not enjoy frustrating arguments over semantics.
With all respect this is as resolved as it needs to be. I do appreciate all the advice given but any more analysis or opinion is not really necessary. I'd be happy if you would accept that I have as complete an understanding as I need to form an opinion of what has been said. Thanks again for the input.
Any level of biology beyond high school will show that the view point you have given is naive at best. you have purposely picked the name of an anatomical feature, and presented it as a grand conspiracy to mislead the worlds population. Biological studies do not lie, the structures, BOTH ARCHES AND SLITS are present in human embryos, do you have empirical evidence that shows otherwise?
Your current conclusion is based entirely on how these structures, seen in the development of chordates, are refered to in lay publications, with no reference at all to peer-reviewed or actual biology texts. Yet you seem to feel that One blog and an ambiguous forum post are enough to declare that the structures are not there.
Horse. Dead. Flogging.
« Could there be other kind of life/civilizations in our past? | The first Americans may have been Japanese? » |