Evolution (Introduction)

by David Turell , Thursday, October 15, 2009, 01:14 (5517 days ago) @ dhw


> I'm going to be stubborn, not because I know anything, but because I still find it hard to follow the reasoning. 
> 
> 1) Scientists tell us that humans and chimps split from a common ancestor about 6 million years ago (but it could have been a lot more). If the theory is correct, it should be possible to find hominid fossils dating back 6 million years or so. We've now found one that dates back only 4.4 million years, so why is human ancestry suddenly turned on its head?-Because of the following quote from the recent studies. It appears that the main line of descent for humans and apes is different. Yes, there was a common ancestor, but the apes stayed much more primative. -Quote:
Ar. ramidus, first described in 1994 from teeth and jaw fragments, is now represented by 110 specimens, including a partial female skeleton rescued from erosional degradation. This individual weighed about 50 kg and stood about 120 cm tall. In the context of the many other recovered individuals of this species, this suggests little body size difference between males and females. Brain size was as small as in living chimpanzees. The numerous recovered teeth and a largely complete skull show that Ar. ramidus had a small face and a reduced canine/premolar complex, indicative of minimal social aggression. Its hands, arms, feet, pelvis, and legs collectively reveal that it moved capably in the trees, supported on its feet and palms (palmigrade clambering), but lacked any characteristics typical of the suspension, vertical climbing, or knuckle-walking of modern gorillas and chimps. Terrestrially, it engaged in a form of bipedality more primitive than that of Australopithecus, and it lacked adaptation to "heavy" chewing related to open environments (seen in later Australopithecus). Ar. ramidus thus indicates that the last common ancestors of humans and African apes were not chimpanzee-like and that both hominids and extant African apes are each highly specialized, but through very different evolutionary pathways.-> 
> 2) The theory has been that the "common ancestor" was "more ape-like" than hominid. so didn't we originally still descend from something that was not human?-Way back before the two lines, ape & hominid developed
> 
> 3) If we really are "different in kind", isn't that because of our brain? But Lucy, we are told, proved that early humans walked upright before they evolved large brains, and Ardi's brain is the size of a chimp's. Is upright walking therefore the criterion for "different in kind"?-Not as I see it. There is more. The hominids were selected (by whom or what)as a separate line that ended up with completely upright walking, better use of hands (we can hammer, they can't) and a huge brain. We did not need a huge brain to survive,any more than apes did. What are we doing here if nature does the selecting? We have gone way beyond what survival required, if one follows Darwin. If we developed from apes and we apparently did not, then we differ in kind, not degree.