But when did our earliest ancestors begin to make connections and start to build on the knowledge of others, setting us apart from other primates? Cumulative culture—the accumulation of technological modifications and improvements over generations—allowed humans to adapt to a diversity of environments and challenges. But, it is unclear when cumulative culture first developed during hominin evolution.

A study published this week in the Proceedings of the National Academy of Sciences by Arizona State University researcher Charles Perreault and doctoral graduate Jonathan Paige, concludes that humans began to rapidly accumulate technological knowledge through social learning around 600,000 years ago.

"Our species, Homo sapiens," said Perreault, "has been successful at adapting to ecological conditions—from tropical forests to arctic tundra—that require different kinds of problems to be solved. Cumulative culture is key because it allows human populations to build on and recombine the solutions of prior generations and to develop new complex solutions to problems very quickly.

"The result is, our cultures, from technological problems and solutions to how we organize our institutions, are too complex for individuals to invent on their own." Perreault is a research scientist with the Institute of Human Origins and associate professor with the School of Human Evolution and Social Change.