Why aren't our evolutionary ancestors extinct?

Discussion in 'Biology & Genetics' started by EmmZ, May 21, 2008.

  1. Oli Heute der Enteteich... Registered Senior Member

    Messages:
    11,888
    It's a good skim.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Enmos Staff Member

    Messages:
    43,184
    Of course, but I doubt Orangutan genetic make-up changed significantly lately.
    Besides, the article EmmZ found didn't exactly agree with the claim either.
    It said it was 'controversial, to say the least'.
    So according to today's scientific findings it is controversial 'to say the least'.
    I also didn't see any arguments to back up this claim.

    The author's premise is that morphology links people and orangutans, despite genetic and molecular studies that say that chimps are our closest relatives.
    Anyone that knows what convergent evolution is, knows the claim is bull..
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Enmos Staff Member

    Messages:
    43,184
    The author's claim rests on morphology.
    Behavior would have been even worse though..

    Please Register or Log in to view the hidden image!

     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. madanthonywayne Morning in America Staff Member

    Messages:
    12,461
    The purpose of the physical change was that brute force, sheer physical strength turned out to not be the most important factor in the survival of the genus homo.
     
  8. Buckaroo Banzai Mentat Registered Senior Member

    Messages:
    332
    I simply can't understand how someone can really defend such thing by now. It was pretty much a viable, if not preferable, hypothesis, before the emergence of all the molecular data, but now... impossible. Unless we're allowed to make really crazy ideas about how pseudo-genealogical patterns of acquisition of RNA viruses could happen and things like that.

    At the same time, that does not mean that all the similarities are meaningless, actually, some people propose "alternative" hypotheses that take these evidence as more relevant than just the bare statement that chimps and gorillas are more closely related to us.

    For some people, bipedal apes came first, as bipedism is/was somewhat already present in arboreal apes, which are the ancestors of both the lienages of bipedal "apes" (australopithecines, humans, etc) and knuckle-walkers (gorillas and chimps). Then instad of bipedism being an "evolved" trait of our lineage, it would have been just a betterment of secondary bipedism of arboreal apes, while knuckle-walking evolved independently on the other lineages. Some people even propose that chimps descend from Australopithecines.

    The overall "humans retained and improved secondary bipedism" is a rather old hypothesis, actually, but it's being "revamped" recently by some researchers.


    And how does that connect with the evidences that Schwartz (and hopefully no one else) cites to defend that orangutans are our closest relatives? Well, basically it would all have been inherited from a common ancestor between humans, chimps, gorillas and orangutans, along with bipedism, but lost in the lineages of chimps and gorillas.

    Some old school theorizer of that idea (I don't remember his name, I guess I read about it in "Lucy: the beginnings of mankind" by Johanson and Edey or "the ascent of man" by Pilbeam) proposed that it happened due to some sort of "evolutionary pressure" that lead the other African apes to diverge from "pre-humans" (while the orangutans remained "safe" in Asia), a sort of selection for "character displacement".

    I think it sounds pretty convincing overall; not only the knuckle-walking seems to me to be more plausible to evolve twice than full bipedism from knuckle walking, even if only once, but many other things seems to be coming together with this idea recently (or at least I had this impression from a few news along the last years, that seemed to fit together).

    And I also think that something similar perhaps happened with lions and leopards, which, despite of being more closely related to each other, are far more physically/adaptively different than lions and tigers. Which, of course, is not an evidence per se that the same happened in the apes case, but a whole different episode, which would only illustrate that perhaps this thing could happen at this continental level. But that's just my layman's guesses, anyway.
     
  9. Buckaroo Banzai Mentat Registered Senior Member

    Messages:
    332
    And there's no real problem with some species being more phenotipically and behaviorally similar to some not-so-close relative than to it's closest relative known.

    Perhaps the better illustration of that would be different "morphs" of males in some species, or even the normal male and female sexes.

    The different morphs of males are different "models" of males with behavioral and sometimes anatomical adaptations to some sort of reproductive strategy; I think that in some species they are actual diverging lineages within a species that's somewhat like at the point of speciation but still united by the females, but in other they are actually just the product of differentiation by environmental factors (like different sorts of ants or bees of the same swarm or beehive). In both cases, they can differ more from closely related ancestors or individuals than to some other not-so-close relatives.

    And for just the sexes, which is perhaps more easier to visualize, just think of a female chimp and a female bonobo, how they are much more similar, anatomically and behaviorally to each other than to the males of each species. I've read that some bird species are somewhat cryptic, phenotypically indiscernible, by the female alone; you can only tell that there are different species by looking at the males.

    Some other examples could be found probably in dog breeds; if I recal, the chow-chow and or the peklinese is more closely related to the wolves than the german shepherd.
     
  10. Fraggle Rocker Staff Member

    Messages:
    24,690
    Canis lupus familiaris has only had approximately fifteen thousand years to differentiate from Canis lupus lupus, so as you'd expect, there isn't much differentiation. Pick the two most unrelated dogs you can find and there will be more similarity in their DNA (and wolf DNA) than that of a human from Norway and one from Borneo.

    DNA analysis shows which breeds were developed the earliest. I don't remember about the chow chow, but the Peke, Lhasa Apso, Shizi ("Shih-Tzu" in Wade-Giles romanization) and mastiff go back about 8,000 years, which puts them among the very first dogs to be selectively bred by humans. Some of the sight hounds (greyhound, Afghan, saluki, etc.) go back more than 3,000 years. The Maltese was the lap dog of the Roman empresses and Rottweilers pulled their peasants' wagons. But most of the breeds that you see in the USA and Europe aren't 200 years old. The German shepherd was invented in 1899.
     
  11. Roman Banned Banned

    Messages:
    11,560
    I think Buckaroo's point, Fraggle, is that morphological traits aren't necessarily indicative, and often times are straight up misleading, when constructing evolutionary trees. Molecular phylogenetics, presumably, more accurately solves such problems.
     
  12. Ophiolite Valued Senior Member

    Messages:
    9,232
    And the Austrian corporal ten years earlier.
     
  13. synthesizer-patel Sweep the leg Johnny! Valued Senior Member

    Messages:
    2,262
    That is so true - I have a stack of them in my loo for a bit of enlightening reading while I take my morning dump

    Please Register or Log in to view the hidden image!



    Although I also have a stack of old Judge Dredd comics too
     
  14. Koalama Registered Senior Member

    Messages:
    50
    If you are asking. If we evolved from moneys, why are there still monkeys? Then the answer is. We did not evolve from the modren day monkeys.
     
  15. Koalama Registered Senior Member

    Messages:
    50
    Look at the peppered moths or the slight differences in the birds that Darwin studied.
     

Share This Page