Culture likely created a buffer against ancient evolutionary pressures, letting Homo sapiens shrink their jaws and grow calorie-hungry brains rapidly. The oldest fossils attributed to the genus Homo date to around 2.8 million years ago in Africa, where it evolved from Australopithecus, an extinct genus of early hominins. Of course, the last surviving member of this genus, Homo sapiens, were relative latecomers, evolving in Africa some 300,000 years ago. Since evolution doesn’t work toward a goal, earlier Homo species weren’t rough drafts on the way to H. sapiens. What remains is the harder question: which specific cultural behaviors let Homo sapiens slip past constraints that had held for millions of years?