Why is learning proof of culture? This idea permeates the report that chimpanzees, can learn from each other how to solve a puzzle.[1] Or perhaps its the fact that when two chimps were taught different ways to solve the puzzle, some chimps learned from one and others from the other, and they did not seem to settle, as a group, on a single solution, but rather to stick with the one they learned initially. To me this seems not an indication of culture, but an indication of stupidity. They failed to rationally evaluate which solution was most efficient, and settle on that one. Rather, it demonstrates simple utility, once they found a solution, they were not interested in learning others.
[1] BBC News. "Chimpanzee culture 'confirmed'" BBC News (World Edition, online). 2005-08-22 http://news.bbc.co.uk/2/hi/science/nature/4166756.stm