The Monkey Effect

Bearded capuchin monkey(Adobestock)

There are fancy obsidian blades from Mesoamerica and deftly knapped Clovis points, but many stone tools look, to the uninitiated, like … well … rocks. This is especially true of some of the simplest, oldest human-made artifacts. But there are reasons that a paleoanthropologist can pick up a seemingly random rock and say, “This was made by human hands.” There’s more or less no known natural mechanism that breaks certain kinds of rocks in a way that