Humans didn't begin major agriculture until about 10,000 years ago. But 20,000 years before that they were grinding their own flour, a new study (in press) suggests, adding more proof that our forebears were eating the beginnings of a more balanced diet while still roving as hunter-gatherers. Anna Revedin's team says in today's Proceedings of the National Academy of Sciences that they found traces evidence of flour still stuck in 30,000-year-old stones the team found in Russia, Italy, and the Czech Republic.