Did Lucy Walk On the Ground or Stay in the Trees?:
Dec. 31, 2012— Much has been made of our ancestors “coming down out of the trees,” and many researchers view terrestrial bipedalism as the hallmark of “humanness.” After all, most of our living primate relatives — the great apes, specifically — still spend their time in the trees. Humans are the only member of the family devoted to the ground, living terrestrial rather than arboreal lives, but that wasn’t always the case.