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.'"

Re:Difficult concept: that more complex != better

[cyborg_zx]

It reinforces the mistaken view that evolution is a progression towards a goal - the true picture of evolution is tree-like.

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:

• O1 is the parent with genome G1
• O2 and O3 are the offspring with G2 and G3
• O4 - O7 are the offspring with G4 - G7

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.

Re:Difficult concept: that more complex != better

[Kozar_The_Malignant]

>it's not that man's ancestor was an ape, it's that apes and man have a common ancestor that was neither ape nor man.

Any objective taxonomy of primates includes Homo, Australopithecus, and the other human ancestors among the African great apes (family Hominidae). Not only was our ancestor an ape; we are apes.

Re:Difficult concept: that more complex != better

[cyborg_zx]

The lineage of homo sapiens is a progression towards homo sapiens. This is a fact. If someone wants to see the lineage of modern humans, the iconic picture is fine representation of this.

You are somewhat missing the point. Yes, you can create a progression going back through your ancestors but that is using the word in a different sense to the idea that there is an end-point and start-point with an inevitable journey from one to the other, that is to say it has a presumption that humans had to evolve that some of the creationist rhetoric likes to engage in.

For example, if you take my ancestors over the last 20,000,000 years there has been an average upward trend in brain size. It may have had ups and downs, but there is an undeniable trend.

This underlies my point - YES, there has been an upward trend in brain sizes but that IS not because evolution was working in some goal based sense towards big brains. If you examine the whole tree a different picture emerges where bigger brains doesn't look like an inevitable end point, merely one possible future solution in one that includes ancestors with brains that are not progressing in that way (as with any other property one may care to examine).

Re:Evolution vs Intelligence

[Kandenshi]

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! >;(

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 /.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 actually some evidence ...

[gondwannabe]

...to back-up your assertion that the rate of evolution can be manipulated environmentally. However, this could be accelleration rather than retardation. In The Ancestors Tale, Richard Dawkins cites the case of Russian researchers' attempts to domesticate the Silver Fox. By selecting for tameness against aggression the foxes we're both behaviorally and physically transformed within 20 generations. They became short, floppy eared and developed spotted, mongrel like coats which (ironically) made them useless for the fur trade.

Dawkins suggests this is powerful evidence that humans have been dramatically changed by their own environmental manipulations - perhaps accounting for the rapidity of our divergence away from our cousins - not easily accounted for by the relatively recent forking of the family tree.

Just another case where the surprising complexity of natural selection can 'play into' the wilful distortions of the creationists.

Re:can't walk without shoes?????

[LF11]

Actually, I run barefoot, and there's a large number of people who run marathons barefoot. Some people even run ultra-marathons barefoot, others run trails barefoot, etcetera. It's not "extreme" or "fringe," although these folks do seem to be remarkably friendly and helpful online.

Barefoot walking and running is actually extremely beneficial for your feet, ankles, knees, legs, and back. Many barefoot runners have discovered that wearing shoes is actually far more damaging and painful than running barefoot.

Chris