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Chimps Evolved More Than Humans
jas_public writes "Since the human and chimp families split about 6 million years ago, chimpanzee genes seem to have evolved more than human genes. The results, detailed in the Proceedings of the National Academy of Sciences, go against the conventional wisdom that humans are the result of a high degree of genetic selection, evidenced by our relatively large brains, cognitive abilities, and bipedalism. The researchers found that 'substantially more genes in chimps evolved in ways that were beneficial than was the case with human genes.'"
So, you get a whole load of species radiating off a single branch, some branches producing further branching, others being cropped and ending that particular evolutionary pathway.
Essentially the process should be viewed as such:
G encodes the information for a genome. The replication of G introduces mutations into that genome into the successors. This is mutation. If we take a simple asexual reproductive organism O1 then:
And so on... we rapidly try out a whole range of G, some of which will be branches that lead to dead-ends (i.e. solutions that produce organisms that are poorly adapted), some will lead to better solutions and eventually some of these solutions will incorporate significant phenotypical changes.
So there was no 'progression' towards homo sapiens, we're just an end point of a huge exploration of a genetic search space.
Neuroscience student here, and yes there do appear to be some growth of new neurons in the adult brain, but at vastly reduced numbers. While we have pretty good evidence for neurogenesis(birth of new neurons) in most parts of the primate brain, there's somewhat less good evidence for it in the neocortex of humans. silly ethics rules slow research down! >;(
/.ers consider themselves to be a bit smarter than average? And the running joke for years has been that none of them get laid. :P Besides, the smart ones are the people who'll use birth control properly right? Instead of just accidently knocking someone up.
There's also somewhat debateable data on what these new neurons do exactly. What the consequences of them are. The data on their being related to learning/memory and such is a bit muddy. They do get functionally integrated in other species anyway, and there seems to be a link to depression. Possibly lower neurogenesis is what mediates stress inducing depression. And the lag of a few weeks before alot of the SSRIs begin to work seems to fit with the few weeks needed for new neurons to be made and mature.
And just to clear one other thing up, these new neurons aren't being made from mature neurons undergoing mitosis and splitting in two. They're made from multipotent stem cells in the dentate gyrus and along the subventricular zone.
As for humans evolving to become smarter, I'm not really sure that being smarted conveys much evolutionary fitness. After all, don't most