I hope a lot of you watched "Discovering Ardi" on Discovery Channel last Sunday. If not, don't miss it tonight! What did you find most intriguing? I was especially taken with Ardi's upright, bipedal walking, but hand-like feet. Biologists thought humans evolved in the savanna, but it turns out the oldest fossil so far, Ardi, evolved in the forest! Lots of new hypotheses needed now about why. First one so far is that human females required mates who could deliver plenty of food for a big, dependent group of offspring. Trees hold plenty of food, bipedal walking leaves the male arms and hands free to bring home the bacon.