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Author | Topic: Neotony in the development of H. sapiens | |||||||||||||||||||||||
Unseul Inactive Member |
Basically i wondered what people's view were on the theory of our origins.
From what i have learnt in my lectures in uni, and then various texts afterwards, im finding it increasingly amusing how we are basically juvenile forms of most of our major ancestors. Neoteny is as far as i am aware the retention of juvenile features (or persisting in a juvenile state). Now just to setup the playing board i think the best example is the origin of vertebrates is thought to be from the sea squirt (dont know how many people have seen these things, they're quite good fun, but just seem pretty useless) However the interesting thing is that the juvenile form is similar to a worm, and has a very basic notochord (prerequisite to spinal column). Here's the first major step that involved using juvenile forms. (having been asked to edit this to give some backups, simple searches on "neoteny" "tunicates" and "vertebrate" "evolution" etc on google will give a good list of what appear to be uni lecture notes on the subject. I attempted to get some papers online but i couldnt get hold of my Athens pass and so couldnt access most of the online journals. I will hopefully be able to back this up with some more journals once i get access again.) The next one which i feel has effected our existence HUGELY is that of our increased intelligence. It is felt once again that we retain a longer childhood, and even extend our degree of learning in adulthood to a much greater degree than even our closest cousins (chimps and gorillas), because we have retained being childlike in terms of interest and curiosity etc. Another neoteny we have kept (though im not sure personally on this one, any confirmation would be nice), is the angle at which our necks are naturally. I have read that during pregnancy the angle of the neck in primates is different for a time, than that of the angle after birth (or during later development in the womb). Whereas we retain this first angle as such. This i suspect would be very useful in terms of comfort whilst having an upright stance permanently. (but as i said im not too sure of the actual skeletons etc or process so not too sure on this one). This idea i think i got from Desmond Morris (The Naked Ape). Once again with access to journals i will hopefully be able to back this up, unfortunatly i borrowed the book and so cant just give the references he used off hand, im sure there will be some more upto date stuff as well tho. Any further examples would be appreciated, any views etc etc. Just thought that a few people out there would find this amusing (probably both creationists and evolutionists, tho for different reasons i suspect). Unseul Give a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.... Do unto others before they do unto you.
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Nicolas Gallagher Inactive Member |
Life-history is extended rather than humans being neotenic relative to the believed common ancestor.
The "angle of the neck" is also due to a novel trait rather than a retention of foetal angle. There are several papers that have demonstrated this. As for human neoteny, I was also very interested in this theory. However, further research led me to believe it isn't correct in regards to human brain evolution at least. If you are interested in reading about this subject in more depth then I have provided a link to my dissertation on heterochronic theories of human brain evolution. link removed edit: provided link rather than full text, corrected errors in the images originally provided This message has been edited by Nicolas Gallagher, 11-28-2004 02:13 PM
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AdminJar Inactive Member |
Welcome Nicholas.
Forum Guidelines suggest that you make your case in your own words and provide links to longer supporting articles. Comments on moderation procedures (or wish to respond to admin messages)? - Go to: Change in Moderation? (General discussion of moderation procedures) or Thread Reopen Requests or Considerations of topic promotions from the "Proposed New Topics" forum or Introducing the new "Boot Camp" forum
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Nicolas Gallagher Inactive Member |
These are my own words, but I've informed my opinion on the research of others as well as drawing on other disciplines I've studied to critically evaluate the assumptions and conclusions other authors have drawn. I did try to find somewhere to host the word file but couldn't. The poster wanted to know opinions on neoteny and so I just thought I may as well post my analysis of the case for human neoteny seeing as it is relevant to what he was interested in. Is this not allowed?
This message has been edited by Nicolas Gallagher, 11-26-2004 06:49 PM
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lfen Member (Idle past 4705 days) Posts: 2189 From: Oregon Joined: |
Jar,
It's cool. The guy has submitted a well cited paper like Bill does on geology. I'm impressed. lfen edit to change typo from "wall" to "well". This message has been edited by lfen, 11-26-2004 11:18 PM
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lfen Member (Idle past 4705 days) Posts: 2189 From: Oregon Joined: |
Jar,
What is also so cool to see this paper is that creationists familiar only with the sketchy arguments of creationist websites can get a better picture of the amount of work scientific reasoning requires and the proper use of citation. It's a very interesting paper to boot. lfen
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AdminJar Inactive Member |
Sure it's allowed. But it is usually less effective to present a long position paper inline. It's usually better to present a summary with links to greater detail. Most ISPs or university systems will provide space to store such material. If you use them them it is best to store it as a text or html file.
{NOTE FROM ADMINNEMOOSEUS - I've posted message 265, concerning this situation, at the "Change in Moderation?" topic. It would be a very good thing to discuss there, but NOT here.} This message has been edited by Adminnemooseus, 11-27-2004 03:55 AM Comments on moderation procedures (or wish to respond to admin messages)? - Go to: Change in Moderation? (General discussion of moderation procedures) or Thread Reopen Requests or Considerations of topic promotions from the "Proposed New Topics" forum or Introducing the new "Boot Camp" forum
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Quetzal Member (Idle past 5900 days) Posts: 3228 Joined: |
Nicholas: Welcome to EvCForum!
An excellent paper and well-reasoned argument. Much appreciated. One question: besides brain structure (which you addressed admirably in that paper), are there other features of H. sapiens that might be considered neotenic? I have heard that the relative hairlessness of human adults is also a neotenic feature. (I've also heard that hairlessness relates to an adaptation for savannah dwelling, i.e., heat exchange). Since this isn't my area, I'd appreciate your thoughts on the subject.
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Nicolas Gallagher Inactive Member |
There are so many areas of human ontogeny being explored for possible heterochronic mechanisms of evolution. One problem with this area of research is the mess that has engulfed the terminology and hence the analysis of data - as is evident in how McNamara deals with brain evolution. Even the bonobo has often been labelled as neotenic relative to the common chimpanzee, but this too seems false. While I havn't researched any area in depth apart from cranial and brain "neoteny", I can add that neoteny is likely to be fairly rare. As I described in that argument, neoteny requires a shift towards isometric growth, which requires positive allometries to "flatten" towards isometry and negative allometries to "steepen" towards isometry. This combination seems unlikely to occur often in evolution. I'm afraid I cannot make any more informed comments in regards to your questions, because I'm simply not knowledgable enough about other people's research in those areas!
"Hairlessness" in humans is generally considered a heat adaptation. Humans have unique sweat glands that are considered a specific adaptation to the environment they evolved in, we can sweat far more efficiently and to a higher degree than any other animal (due to unique sweat glands). I remember reading somewhere that a human could survive ambiant temperatures of 120C if provided with enough water and conditions allowing rapid evaporation of sweat (don't take that as gospel, it's just a memory). However, humans have not lost hair as such, our body hair is simply very small but we still retain roughly the same number of hairs. It would seem more likely that some genetic adaptations suppress extensive hair growth, which could explain why some individuals can be covered in full body hair. I would be sceptical of labelling things as neotenic based on apparent similarities with juvenile apes. But again, I'd have to look at genuine research. Sorry I can't shed more light on your queries
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Ben! Member (Idle past 1427 days) Posts: 1161 From: Hayward, CA Joined: |
Nicholas,
It took me a few hours, but I got through the beginning of the paper, now halfway through the discussion about defining homology. Thanks for posting the paper. The approach is familiar; I'm trying to take a similar approach in the realm of philosophy of language, linguistics, and philosophy of mind The thing that was most difficut for me was to figure out what "morphometrics" was. Now, I've tentatively defined it as "formalism of describing morphological changes during development; provides a way of classifying and comparing the changes." with key terms "shape" and "displace," which I both understand (graphically). Is there a website you would recommend for exploring morphometrics? If not, I'll just use whatever an internet search pops up. This is cool... Thanks!Ben
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Nicolas Gallagher Inactive Member |
Hi,
I'm afraid I don't know any websites that deal with morphometrics, but you're definition is essentially good enough. It deals with measurements of shape and in this context with "measurements" of shape change during ontogeny. Thing is that size and shape are very closely linked so it can be problematic in same cases. I'm impressed that you have spent so long trying to understand all these aspects when it seems you are unfamiliar with the subjects. I have removed the paper from this site, if you have not got a copy of it to read offline and are still interested reading it, then please let me know and I will email you a link thanks Nick This message has been edited by Nicolas Gallagher, 11-28-2004 02:11 PM
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Brad McFall Member (Idle past 5061 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
http://life.bio.sunysb.edu/morph/
see also perhaps; quote: This message has been edited by Brad McFall, 11-30-2004 08:44 AM
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Ben! Member (Idle past 1427 days) Posts: 1161 From: Hayward, CA Joined: |
Thanks Brad.
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