What is \"human\"? (Evolution)

by dhw, Monday, October 19, 2009, 12:28 (5513 days ago) @ David Turell

David has referred us to an article by Ann Gibbons, who clears up some of the misunderstandings that have arisen over the original report on Ardi. The fact that Ardi was not like a chimpanzee has been distorted into claims that humans did not descend from apes (or ape-like ancestors). "Not like a chimpanzee" does not mean "not like an ape". After all, the oldest chimp fossils ever found only go back half a million years, whereas primates are believed to go back about 50 million. However, David points out that at this juncture no-one knows what the "common ancestor" will be like, and ... a great line ... "fossils don't come labeled as in the museum".-I would go a lot further. I don't think there is any way in which we could ever identify "THE" common ancestor. We may find fossils of all kinds of extinct ape-like species, with all kinds of primitive "human" traits, but everything that we find will have descended from something else. All species must have common ancestors, and since we have absolutely no way of knowing what has NOT been discovered, we will still be confined to speculation. I see this as yet another instance of language creating its own reality. We use expressions like "common ancestor" and the old favourite "missing link", and somehow these create a pattern, almost an authenticity of their own ... as if these things are bound to exist because we have words for them. My guess is that there are lots and lots of missing links. -You have also referred us to John McCrone, who argues that human speech is the dividing line between us and all other animals. The physiological changes necessary to allow human speech certainly mark yet another difference, but of course other animals also have a larynx and an epiglottis, and also make sounds with meaning. Our languages are almost infinitely more complex, but once again "more" = degree. I would say the new form/position of palate and larynx, like the altered pelvis and birth canal, are variations on existing structures and therefore not "different in kind". But, as I've said before, this only matters if one wants to argue for special, Genesis-type creation as opposed to evolution. I do think we are special, and language is a crucial part of our "human-ness", but so too are cave paintings, mastery of fire, the invention of the wheel, none of which are connected with speech. For me, it comes down to human intelligence, the seat of which is the brain, and this seems to have expanded very rapidly in homo erectus from chimp-size to roughly our size. Maybe homo erectus is the guy that holds the key.