Calorie boost may explain why adults evolved ability to digest milk

Young children who retain the ability to digest milk benefit from a big increase in available calories, and this may explain why mutations that allow this spread rapidly in some human populations several thousand years ago.

These extra calories would greatly increase children’s chances of surviving infections, as undernourished children are more likely to die if they become seriously ill, says Alexandre Fabre, a paediatrician at the Timone Infant Hospital in Marseille, France, who led the study.

Milk is …