These cute monkeys could change our understanding of human history

In the video above, there is something fascinating happening: a group of Brazilian capuchin monkeys are busily hammering rocks together, often creating sharp-edged stone flakes that spin off in all directions. The presence of those rock flakes has caused a stir in scientific circles. The reason is that over the decades, scientists have often found similar rock chips and attributed their existence to early human tool use. Rocks, when they are split a certain way, make handy cutting tools, ideal for scraping meat off of a dead animal or breaking a bone.