Most experts, though, think this sets the bar too low, and standard biological classifications in fact define the genus Homo (“mankind” in Latin) by bundling together an increase in brain size from 400–500 cubic centimeters to roughly 630 (our own brains are typically about twice as big) with the first evidence for upright apes smashing stones together to create crude tools. Both processes began among bipedal East African apes around 2.5 million years ago.
