Demography and the Appearance of Modern Human Behavior
In Science, 5 June 2009 (Vol. 324. no. 5932, pp. 1298 - 1301):
"Late Pleistocene Demography and the Appearance of Modern Human Behavior"
by Adam Powell, Stephen Shennan, Mark G. Thomas.
Here is the UCL press release:
Increasing population density, rather than boosts in human brain power, appears ...