Humans domesticated themselves 3.5 million years ago by creating stone tools, leading to genetic changes like larger brains and bodies.

“the first domesticated species on earth were humans we domesticated ourselves three and a half million years ago when we started creating these first stone tools and started and because of the creation of these stone tools we could access resources we put ourselves in a culturally human created environment with these technologies stone tools fire and a whole bunch of other things we genetically changed because of and you know through evolutionary processes as a result of this new environment we were in on our ability to access foods we never could before and with the introduction of things like animal uh based foods our bodies and our brains grew to the point that we can no longer we've domesticated ourselves we can no longer survive outside of a culture-created environment”