Too old to take it

摘要

A quick, cheap test to identify people who can't digest milk is now on the cards. It would help hundreds of thousands of people with the condition, known as lactose intolerance, who are never diagnosed because the current tests are time-consuming and unreliable. The test has been made possible by the discovery of the genetic basis for lactose intolerance by Leena Peltonen's team at the University of California, Los Angeles. Her findings support the theory that retaining the ability to digest milk into adulthood is an adaptation that only evolved recently in milk-guzzling cattle herders.