Party Animals: Early Human Culture Thrived in Crowds | LiveScience:
"The research, which is published in the June 5 issue of the journal Science, suggests that tens of thousands of years ago, as human population density increased so did the transmission of ideas and skills. The result: the emergence of more and more clever innovations.
'Our paper proposes a new model for why modern human behavior started at different times in different regions of the world, why it disappeared in some places before coming back, and why in all cases it occurred more than 100,000 years after modern humans first appeared,' said study researcher Adam Powell of the Arts and Humanities Research Council Centre for the Evolution of Cultural Diversity at University College London.
The idea that demography is linked to modern human behavior has been around for decades, but this is the first time scientists have run computer models and actually tested out different hypotheses, said Richard Potts, an anthropologist and director of the Human Origins Program at the Smithsonian Institution's National Museum of Natural History in Washington, D.C."