BELGIUM: How long did Neanderthal infants breast-feed? A new study examined the mineral content of teeth of modern humans and macaques and found that elevated levels of barium are a reliable indicator of the ingestion of breast milk. They then applied this test to a fossilized Neanderthal tooth from Belgium, and found that the child was breast-fed exclusively for seven months, followed by seven months of mother’s milk supplemented with other foods. Using the technique on other well-fossilized Neanderthal remains might help show if such abrupt weaning was common among them. —Samir S. Patel