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On evolution of humans and that of other animals: any discrepancy?

  1. Sep 7, 2013 #1
    Question Summary:

    Do you think human evolution worked in the same way as other living things have evolved through natural selection?

    Don't you think the human evolution occurred faster than that of any other animals? And humans have possessed too many characteristics ( especially those of their brains ) compared with other animals who evolved through natural selection?


    I want to first talk about my views on evolution.

    I know that natural selection did occur. I know the process of natural selection is how living things evolved. ( The holy grail is the fossil of Archaeopteryx, if anyone still has any doubts. And please keep it mind that they had bony tails if you are reading any creationist's article. )

    I also want to admit that I have little idea on human evolution. If you can recommend me any good book on human evolution, I would be very grateful.

    However, human evolution always seems rather odd to me. I mean, humans can do what no other animals can do. It has a huge brain capable of solving complex mathematical problems, building giant telescopes to understand better how the universe works and giant machines as big as a city such as Large Hardon Collider. Humans have sent machines on other planets. Humans have a brain that is capable of thinking and communicating in complex languages. None of other animals do have such abilities, at least not at this scale, and none have all of them ( some dolphins, for example, do have language, but use only a few words, and certainly they didn't build telescopes. )

    Humans have gone through a phase in their evolution known as ''Rapid brain expansion.'' From mere apes, within about a million years, we have become ''humans'' who are capable of thinking complex stuff, and building tools while no other animals don't even seem to understand what these things are. I know bipedalism has helped human hunt and collect food more efficiently, and better food means better population; and better population means better chances of different offspring.

    But the fact that all of the different and complex parts of human brain have evolved in such a short time always makes me wonder if this could work just by random genetic mutations and natural selection. Natural selection usually takes a long time, since you have to ''pass in the tests'' of nature to ensure that your species would continue with a newly acquired feature. Doesn't it make you wonder that how so many changes in the environment have taken place in such a short period of time, which some of the ancestors of humans had to pass to ensure only their offspring make it to the next generation, while those with offspring who lacked such features would just die out?

    Yes, I wonder if the nature was somehow ''tuned'' in an extraordinary manner ( and by ''extraordinary'', I mean ''extra-natural-selection-ordinary'' ) for our evolution?
    Last edited: Sep 7, 2013
  2. jcsd
  3. Sep 7, 2013 #2
    Define faster evolution? first of all what do you think evolution in biology mean? Development of technology ? Evolution has no goal, it simply is the idea of populations surviving over long period of time with adaptation and speciation. One recent definition involves change in allele frequency over time.

  4. Sep 7, 2013 #3

    jim mcnamara

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    Evolution is science, not opinions. Try to find some evidence from a book or in scientific literature to show what you think. Currently I am not aware that your hypothesis has has any backing.

    One proposed model for the evolution of increasing human brain size and concomitant changes in social abilities -- exploits the fact that central Africa changed climate cyclically with a period of about 50000 years, from wet to very dry to wet again during the time humans were evolving. However all animals and plants there were subject to the same environmental pressures. See if you can work with that model. Check out: 'The Social Conquest of Earth' by E. O. Wilson. It is accessible for non-technical people.

    Please cite sources, don't post "my view", because the thread will be shutdown. See the very first PF page.
  5. Sep 7, 2013 #4


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    No. Please stick to mainstream science.
  6. Sep 7, 2013 #5
  7. Sep 7, 2013 #6

    D H

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    Other animals use tools. Other animals have dexterous limbs. Other animals have large brains. Intelligence has arisen multiple times in a wide range of species. Even some birds and some octopi are quite intelligent. About the only thing we do have that apparently is unique is the gift of gab.

    The split between chimps and humans occurred somewhere between five to seven million years ago, depending on who you read. Australopithecines appeared about 4 million years ago, the first homo species about 2.4 million years ago. It wasn't all that sudden.

    So what do we have that's unique, at least amongst our ape brethren? It's the gift of gab. We have language. With that ability, we can teach and learn, teach and learn some more. While our physical, mental, and verbal evolution was Darwinian, the knowledge that those mental and verbal skills enabled did not evolve in a Darwinian sense. With language, stuff learned by one generation can be passed to the next.
    Last edited: Sep 7, 2013
  8. Sep 7, 2013 #7


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    For clarification, jim was talking about a period of 50,000 years, not "50,000 years ago".

    (I think he's referring to the Sahara pump theory.)
    Last edited by a moderator: Sep 7, 2013
  9. Sep 8, 2013 #8

    jim mcnamara

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    I was just coming up with one of several possible explanations and giving a citation. Indeed. the 'Pump Theory' applies to 50000 year cycles of climate change over a much longer period than 50000 years.

    My homespun example lost something of the real deal.
  10. Sep 10, 2013 #9
    Sorry about my late reply.

    While I'm checking on your link, you may want to have a look at this or this article.

    For example, modern horses took about 7 million years to evolve from their ancestor Pliohippus, which involved only a few significant anatomical changes. However, chimpanzees and humans shared a common ancestor about 7 million years ago, too, but I'm sure we have significant differences in anatomical structures, such as bones to support bipedalism, opposable thumb, anatomical structures for production of voice, and associated brain areas for them.

    On the other hand, cichlid fishes are known to evolve relatively very rapidly, several new species are discovered almost every year.
  11. Sep 10, 2013 #10
    Thank you very much for your answer.

    I wanted to understand how humans have evolved, and I have no problems in acknowledging my ignorance of the subject. However, I don't think it's too much for someone to wonder exactly how humans have evolved to such degree in such a short period of time.

    I think I have found the answer, though ( Thanks a lot to D H ). It was probably first the appearance of bipedalism, then opposable thumb and then acquisition of language. While environment must have been significantly influenced by environment, opposable thumbs I think made our ancestors benefit themselves regardless of the environment since it enabled us to make tools and hunt more efficiently. And when you have opposable thumb, you have the ability to manipulate a lot of resources of nature, and to make the best use of it, language must have been very useful later. I certainly have missed the role of sociocultural in human evolution before.

    But of course, I might be wrong. Please let me know if you think I've missed something, or worth correcting.

    Thanks for the reference of the E. O. Wilson book.
  12. Sep 10, 2013 #11
    Thank you very much for your great answer. And sorry about my late reply.

    You have given a really strong point: language, which I have missed. And I certainly do not defend my ignorance of the role of sociocultural influence in the course of human evolution.

    However I think humans must have gone through at least three very important anatomical changes in the course of their evolution which can be explained by genetics before being able to be efficient at communication through use of language. The anatomical changes should be bipedalism, opposable thumbs, and anatomical structures related with production of voice ( and the associated parts of the brain ). While bipedalism should have been influenced greatly by environment, the appearance of the opposable thumbs was almost sure to happen next. To have better hands to manipulate the resources of nature means you can outlive your cousins who can't by hunting-gathering better. And of course, if you can use a lot of things from nature for your own advantage, it would be helpful to have a good chunk of the brain dedicated to memory.

    Of course, then came the next triggering point. If you can associate some sound that you can produce with parts of your body with a specific thing or action, it would be very valuable, since you can teach your children what to do in a specific situation or how to do it. That should enable one generation of your species pass what you've known in your lifetime to your offspring. And the rest of the story of evolution may only be the consequence of combined sociocultural contribution.

    But of course, I might be wrong. Please let me know if you think I've missed something, or any point I have made is worth correcting.
  13. Sep 10, 2013 #12
    I'm just flabbergasted no one is mentioning punctuated equilibrium. Really I'm a little disappointed people. Wait, let me re-read everything the poster asked . . . yep, everyone of them can in my opinion be adequately explained by Gould's greatest contribution to Biology.
  14. Sep 10, 2013 #13


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    Just a note about punctuated equilibrium: Gould was studying only bones: morphology... not the complete molecular picture and not all aspects of evolution. Additionally, just because you're missing samples in between, doesn't mean they don't exist. It might mean that global volcanic events that preserve the bones aren't always occurring, but occur in intervals.

    Robert Sapolsky covers this some in his open lectures "Human Behavioral Biology". He talks about the history, an argument between (iirc) the molecular biologists saying "evolution is gradual" and the paleontologits saying "evolution is step-wise", but propositions that perhaps evolution is both, and different aspects dominate in different domains.

    I don't know what time-scales "step-wise" vs. "gradual" actually imply quantitatively, or how it compares to the OP's "rapid expansion", though.
  15. Sep 10, 2013 #14
    Actually the difference in the anatomical structures are trivial as far, i know. Maybe an expert talk about it.
    Bipedalism existed even before homo sapiens arrived, You should know, we belong to the hominid family of which many extinct groups found in the fossil records had one or more of our niches like bipedalism even perhaps opposable thumbs.



    Even bonobos are known walk on two legs occasionally.


    Neanderthals(closest to homo sapiens) had some sort of language and social gathering, even buried their dead.

  16. Sep 10, 2013 #15
    No, there are significant anatomical difference. Read this article. And this.

    The holy grail of human evolution is bipedalism. No other ape walk on their two feet ( many COULD, but I'm not talking about them now) full-time. And the references you gave: ''Bipedal walking has been recorded as less than 1% of terrestrial locomotion in the wild.'' Well, maybe we can stay under water without oxygen tank for less than 1% of an hour. But that doesn't mean, we are as good as fish.

    And about opposable thumb. Our opposable thumb is unquestionably different than that of any other ape. From wikipedia: '' In apes and Old World monkeys, the thumbs than can be rotated around its axis, but the extensive area of contact between the pulps of the thumb and index finger is a human characteristic.'' And without the kind of thumb you have, you couldn't make so many efficient tools. And one more point, anatomy includes neuroanatomy as well. Your brain is significantly different than your ape cousins, at least by volume, and in the areas involved in the process of cognition.

    And yes, many now-extinct primates were able to walk on their two feet including Neanderthals. And as you said, Neanderthals are one of our closest evolutionary cousins. That doesn't contradict the fact that there are significant differences between us and chimpanzees.
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