Earth Log 0010 Becoming Human

The previous entry ended in the early Eocene, with the small, large-eyed, tree-dwelling primate Teilhardina moving rapidly across the Northern Hemisphere during a brief warm spike at the boundary between the Paleocene and Eocene epochs. The basic primate body plan — forward-facing eyes, grasping hands, social groups, long childhoods — was in place. What had not happened, and would not happen for another fifty million years, was that any branch of the primates climbed back down out of the trees.

This entry follows what happened when one branch did. It covers the appearance of the earliest hominins, the move to habitual bipedal walking, the manufacture of stone tools, the appearance and expansion of the genus Homo, the use of fire, the brief mid-Pleistocene world in which several human species lived simultaneously, the appearance of Homo sapiens, and the spread of Homo sapiens across every continent of the planet by the end of the last ice age. The story closes about twelve thousand years ago, just before the agricultural revolution that begins the next major arc of the project.