Humans had invented style. Chipping stone tools this way, rather than that way, now marked a group off as different from their neighbors; chipping them a third way marked a new generation as different from their elders. Change remained glacial by the standards we are used to, when pulling out a four-year-old cell phone that can’t make movies, locate me on a map, or check e-mail makes me look like a fossil, but it was meteoric compared to all that had gone before.
