I had the chance to talk to biological anthropologist Dan Lieberman of Harvard late last week for a story on the evolution of upright walking. He had a really great line I wasn't able to work into the piece, but wanted to share. He was explaining to me that right now wild chimps walk about a mile and a half a day--not nearly enough for natural selection to adjust for the high energy cost of knuckle-walking. "That's like dieting by eating five fewer M&M's a day," he said. Which reminds me: is it lunch time yet?