One year is really long. Ten is an era. A hundred is a lifetime. A thousand is a millennia. Ten thousand is incomprehensible. A hundred thousand years—unimaginably vast. Yet two million years. Two million years is the amount of time, give or take, that nature has been thoroughly employed with this side project. The human species is a project that seems fresh, new, and cutting-edge. Yet it has been a work in progress for countless millions of years, if not billions. We like to fancy ours...