From BBC News:
By comparing modern man with our ancestors of 37,000 years ago, the Chicago team discovered big changes in two genes linked to brain size. One of the new variants emerged only 5,800 years ago yet is present in 30% of today’s humans, they believe. This is very short in evolutionary terms, suggesting intense selection pressures, they told Science. Each gene variant emerged around the same time as the advent of so called “cultural” behaviours. The microcephalin variant appeared along with the emergence of traits such as art and music, religious practices and sophisticated tool-making techniques, which date back to about 50,000 years ago. It is now present in about 70% of humans alive today.
Researcher Dr Bruce Lahn said the big question was whether the genetic evolution seen had actually caused the cultural evolution of humans or was merely chance. Their hunch is that it might have something to do with the important role that these genes play in brain size, but stressed that did not necessarily mean better intelligence.
More here.