Evolution (Introduction)

by dhw, Friday, October 16, 2009, 11:50 (5516 days ago) @ David Turell

I pointed out that if humans and apes split from a common ancestor approx. 6 million years ago, it should be possible to find hominid fossils that go back 6 million years. David responds: "Yes, there was a common ancestor, but the apes stayed much more primitive." That seems to me to be in line with the original theory, but you go on to quote from the research publication, which concludes:-"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."-Forgive me if I continue to go my own ape-like way, but there are things that remain unclear to me. I don't understand how one can draw conclusions about the "last common ancestors" through a hominid fossil from approx. 1.6 million years later than those ancestors. Nobody knows what the common ancestor was like, but it seems reasonable to assume that it was more primitive than its descendants. Ardi was already a hominid, even if she was not as advanced as Australopithecus. The fact that she was different from modern chimps (which for all we know may also have evolved) and followed a different evolutionary path is surely only to be expected if the split had taken place 1.6 million years earlier. So what's new?-I like your point that apes didn't need huge brains to survive, but isn't that precisely how evolution works? The earliest living things didn't need eyes, legs, sexual organs to survive, but each innovation that bestowed any sort of advantage was preserved by natural selection. The old organisms often continue to survive (think of bacteria), while the new organisms progress. So although the huge brain was not a necessity, once it was there ... just like eyes, legs, sexual organs ... it turned out to be very useful. It survived, and it developed, while the less brainy apes continued to go their own way. In any case, Ardi didn't have a huge brain. Nor did Lucy. Their brains were more chimp-sized than human-sized. Couldn't that fit in with the idea that they still retained features inherited from a common ape-like ancestor? -As for "different in kind", our brain directs our movements, actions, reactions, perceptions in the same way as that of the apes. But ours is bigger, more complex, more versatile. "More" = degree, not kind, but I can't see that the distinction matters unless you want to discount evolution altogether (which I know you don't) and defend the religious claim that man is a special creation. However, if you believe in a Creator, you can argue that each evolutionary step forward is God making progress towards his ultimate invention: the thinking machine that is man. With the apes he got pretty close, but there was still something missing....so he fiddled with the pelvis, the hands, and above all the brain till he got us. Or you can say he set up the programme for it all to happen. But this scenario also has apes and hominids splitting from a primitive unknown common ancestor, and evolving their own separate ways, with the hominids developing eventually into us. And so, in conclusion, I still don't see how Ardi ... as one of the evolving hominid line ... disproves Darwin.