The Self-Domestication of Humans
We domesticated ourselves. "Dr. Leach listed four characteristics of the bones of domesticated animals: They mainly have smaller bodies than their wild ancestors; their faces tend to be shorter and don’t project as far forward; the differences between males and females are less highly developed; and they tend to have smaller brain cavities (and thus brains). As it turns out, all of these changes appear in human fossils. Even our brain size fits the pattern: While the human brain grew steadily over the last two million years, that trajectory took a sudden turn about 30,000 years ago, when brains started to become smaller."