When Rick Potts started digging at Olorgesailie, the now-dry basin of an ancient Kenyan lake, he figured that it would take three years to find everything there was to find. That was in 1985, and Potts is now leading his fourth decade of excavation. It’s a good thing he stayed. In recent years, his team has uncovered a series of unexpected finds, which suggest that human behavior and culture became incredibly sophisticated well before anyone suspected—almost at the very dawn of our species, Homo sapiens.
The team found obsidian tools that came from sources dozens of miles away—a sign of long-distance trade networks. They found lumps of black and red rock that had been processed to create pigments—a sign of symbolic thought and representation. They found carefully crafted stone tools that are indicative of the period known as the Middle Stone Age; that period was thought to have started around 280,000 years ago, but the Olorgesailie tools are between 305,000 and 320,000 years old.
Collectively, these finds speak to one of the most important questions in human evolution: When did anatomically modern people, with big brains and bipedal stances, become behaviorally modern, with symbolic art, advanced tools, and a culture that built on itself? Scientists used to believe that the latter milestone arrived well after the former, when our species migrated into Europe between 50,000 and 60,000 years ago, and went through a “creative explosion” that produced the evocative cave art of Lascaux and Chauvet. But this conspicuously Eurocentric idea has been overturned by a wealth of evidence showing a much earlier origin for modern human behavior—in Africa, the continent of our birth.