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Originally Posted by Ambient1
Only within the last 10,000 years is there any form of recorded history.
The only thing I can think of, is that somehow our brains changed around 10,000 years ago. And changed in a big way (emergence of symbolic thought perhaps?). But would that not mean that we are a new species?
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Do you want the long or the short answer?
The short answer is that yes we are still evolving, there is a significant difference between H. sapiens 100kya and today, particularly in body size and dentition. The face, jaw and teeth of a mesolithic hunter (10kya) are around 10% more robust then those of modern humans, this is thought to be due to the differences in lifestyle e.g. the adoption of agriculture.
The dramatic shift to modern behavior can be explained in two ways - Soffer argues that it was due to social relationships and development of kinship groups, this is debatable as there is evidence for strong kinship links as far back as H. antecessor and the Neanderthals were the first to bury their dead and care for the elderly.
Klein on the other hand argues for a biological change that preceeded fully modern behavior. He believes that a neural reorganisation led to development of new behaviors and cites the newly discovered FOXP2 gene as evidence. FOXP2 thought to control facial movements that lead to the development of sound and its mutation leads to great problems articulating speech. It was discovered by studying a family that in which some members had difficulty both in producing and in processing speech. The gene was localized to the seventh chromosome and subsequently identified as the FOXP2 gene. When compared with other mammals, specifically mice and primates, it was found that it differs by only three amino acids and of these only two are unique to humans.
These are two of the arguments for the development of more complex behavior at around 40/50kya. There is also the argument put forward by Bahn, specifically to do with the development of art, that fully modern symbolic behavior had been around for a lot longer then it is thought but had to do with behavior that is not preserved in the archaeological record. For instance any ritual marking on skin, such as painting or scarification, would not have been recorded.
There is also some evidence for culture before 35kya - such as at Bilzingsleben in Germany a piece of engraved bone was found that was dated at approximately 300,000 years old, while at the Golan Heights in Israel there was found a Venus figure from approximately the same time period. This figure is remarkable in the fact that it has a clearly incised neck separated from the body and that there are two grooves delineating the arms. While no one is arguing that H. erectus carved this out of a piece of formless rock, this is debatable evidence for the production of some sort of art much earlier then the Upper Paleolithic.
The big change at about 10kya is the develpment of agriculture and more sedentary cultures, the so-called "Neolithic Revolution." It seems that all hierachical societies developed after agriculture was adopted, it is thought that storage of food and it's dispersal would have meant that a more structured society was needed then the previous more egalitarian hunter-gatherer societies. From these more structed societies developed and this led to the culture explosion that has been termed the "Neolithic revolution."
If I go into the origins of agriculture and it's significance I could be here all day and I have way too much revison to do for that. If anyone is really interested I'll try to get round to it over the weekend.
So far there is no genetic evidence that there was a major genetic/neural shift at 10kya. It seems to be agriculture that influenced it more. And symbolic behavior has been around a lot longer then 10kya, anything between 300kya and 40kya depending on which theory you subscribe to.
And that was the short answer!