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Thread: Scientists Cite Fastest Case of Human Evolution

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by roughdraft274 View Post
    I can't really talk to you about the genetic bottlenecking of each individual species, but it seem s that there are at least a few other species that hit this same problem at around the same time that is talked about in the link.
    Ok, but still, why are they so much more genetically diverse than humans? Unless far more humans than chimps died, leaving far more chimp survivors, then the impact should be about equal, right?

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by mac View Post
    Ok, but still, why are they so much more genetically diverse than humans? Unless far more humans than chimps died, leaving far more chimp survivors, then the impact should be about equal, right?
    Why do humans have to have the same genetic diversity as chimps? Could one make the same argument when comparing cheetahs to other big cats?

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by mac View Post
    Ok, but still, why are they so much more genetically diverse than humans? Unless far more humans than chimps died, leaving far more chimp survivors, then the impact should be about equal, right?
    I don't know.

    There could have been many more chimps in the first place. That's just the first thing that comes to mind.

    Is there something you're getting at? Are you saying that since we aren't as genetically diverse as chimps we didn't share a common ancestor?

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by roughdraft274 View Post
    I don't know.

    There could have been many more chimps in the first place. That's just the first thing that comes to mind.

    Is there something you're getting at? Are you saying that since we aren't as genetically diverse as chimps we didn't share a common ancestor?
    I've read that it indicates we are a much younger species. Doesn't make sense to me if we are descendant from a common ancestor. Was wondering what other's take on it was before I suggested this in order to get an unadulterated opinion.

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by mac View Post
    I've read that it indicates we are a much younger species. Doesn't make sense to me if we are descendant from a common ancestor. Was wondering what other's take on it was before I suggested this in order to get an unadulterated opinion.
    It could mean many things.

    If the population of humans and chimps bottlenecked at the same time as is plausibly presented in the linked Toba article, then perhaps the chimps managed to have a couple of populations that had previously diversified come together with less territorial pressures. perhaps the chimps had a few more paternal figures that added their genes to the mix (and actually differences in monogamous human versus chimp opportunistic mating behaviors make it quite plausible that a diversified group of male chimps passed their seed versus a very narrow selection of human males). Perhaps humans killed of each other, or perhaps there was a scenario that fits the stereotypical Amazon women tales where they killed off all the men except for one who then impregnated them all. Perhaps any of these, or a million other scenarios or situations that might explain it.

    We do not have sufficient evidence to explain why our bottleneck only allowed a few variants through, while chimps may have had more, and when the sample size is reduced substantially even extremely slight variables can make a dramatic difference in potential outcomes.
    Last edited by marduc; 07-07-10 at 05:00 AM.
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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by marduc View Post
    It could mean many things.

    If the population of humans and chimps bottlenecked at the same time as is plausibly presented in the linked Toba article, then perhaps the chimps managed to have a couple of populations that had previosly diversified come together with less territorial pressures. perhaps the chimps had a few more paternal figures added their genes to the mix (and actually differences in monogomous human versus chimp opportunistic mating behaviors make it quite plausible that a diversified group of male chimps passed their seed versus a very narrow selection of human males). Perhaps humans killed of each other, or perhaps there was a scenario that fits the stereotypical Amazon women tales where they killed off all the men except for one who then impregnated them all. Perhaps any of these, or a million other scenarios or situations that might explain it.

    We do not have sufficient evidence to explain why our bottleneck only allowed a few variants through, while chimps may have had more, and when the sample size is reduced substantially even extremely slight variables can make a dramatic difference in potential outcomes.
    What about the concept that we are actually an offshoot of Chimps. There is evidence that early humans interbred with Chimps.

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by mac View Post
    What about the concept that we are actually an offshoot of Chimps. There is evidence that early humans interbred with Chimps.
    what???
    We are an offshoot of chimps and we have interbred? What and where is this evidence you allude to?
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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by marduc View Post
    what???
    We are an offshoot of chimps and we have interbred? What and where is this evidence you allude to?
    News in Science - Early humans had sex with chimps - 18/05/2006

    I haven't followed up on it much more than these few articles...other then the genetic diversity part.

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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by mac View Post
    News in Science - Early humans had sex with chimps - 18/05/2006

    I haven't followed up on it much more than these few articles...other then the genetic diversity part.
    Talk about a misleading headline. No one was having sex with chimps, our common ancestors were having sex with each other, and prior to the populations actually becoming speciated it is possible the two seperate lineages were still able to interbreed for a while

    From your article:
    "It is possible that the Toumai fossil is more recent than previously thought. But if the dating is correct, [it] would precede the human-chimp split," he says.

    "The fact that it has human-like features suggest that human-chimp speciation may have occurred over a long period with episodes of hybridisation [inter-breeding] between the emerging species."

    A gradual divergence of species through hybridisation, rather than a quick break, may be far more common than we suspect.
    So our common ancestor was able to interbreed for a while before the two populations split into what became chimps and humans, This is how speciation works, eventually the changes add up to the point where they can no longer interbreed, and they become divergent populations that continue to drift further apart over time.
    Last edited by marduc; 07-07-10 at 05:15 AM.
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    Re: Scientists Cite Fastest Case of Human Evolution

    Quote Originally Posted by marduc View Post
    Talk about a misleading headline. No one was having sex with chimps, our common ancestors were having sex with each other, and prior to the populations actually becoming speciated it is possible the two seperate lineages were still able to interbreed for a while

    From your article:


    So our common ancestor was able to interbreed for a while before the two populations split into what became chimps and humans, This is how speciation works, eventually the changes add up to the point where they can no longer interbreed, and they become divergent populations that continue to drift further apart over time.
    I don't read it to say that. What I get is that early humans and chimps were close enough to interbreed (like chimps and bonobos) for awhile and then diverged further. Added to the greater diversity of chimps than humans, that means we are spin off of chimp rather then two separate species descendant from a common ancestor.

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