Party Animals: Early Human Culture Thrived in Crowds
"The basic idea conceptually is you can have individuals who are really great at inventing ideas and concepts and ways of approaching the world, but you need a certain population density to be able to have that stuff catch hold and spread," Potts told LiveScience.
He added, "You could imagine that there may have been very innovative individuals on occasion, but with very small population sizes and mobile foragers who didn’t run into other groups very often, those innovations were probably very short-lived and almost invisible in the archaeological record."
http://www.livescience.com/culture/090604-human-behavior-evolved.htm
