Have you ever drunk a big glass of milk or eaten an ice cream cone and then felt sick to your stomach afterwards? If so, you might be one of the estimated 30-50 million Americans who have difficulty digesting milk and other dairy products and are said to be “lactose intolerant” (lactose is the sugar present in dairy products such as milk). Worldwide, the ability to drink milk as an adult is actually a rare one. Babies, of course, need to be able to digest the energy-rich lactose sugar in their mother’s breast milk, but for most people the ability to break down lactose disappears during childhood as expression of the gene that allows digestion of lactose gradually gets turned off. However, the percentage of adults who retain the ability to digest lactose (this ability is referred to as “lactose tolerance”) as adults varies greatly among different populations. Scientists investigating why some populations have higher rates of lactose tolerance have found that this ability is likely to be intricately connected to the agricultural habits of our distant ancestors… Continue reading Got lactase? How (some of) our bodies evolved to enjoy milk with our cookies