First Direct Evidence of Human Evolution in Response to Natural Selection

According to a new study of fossilized bone samples, Europeans were unable to digest milk as recently as 7000 years ago. Today, more than 90% can. How has this change occurred?

A study lead by Mark Thomas at the University College London proposes that the genetic makeup of Europeans evolved because the ability to drink milk enabled them to take in more nutrients, giving them a massive survival advantage. Doctor Thomas points out that unlike nourishment from seasonal crops, milk from cows is available for nourishment all year long. It is also uncontaminated by parasites, making it safer to drink than stream water. Low levels of sunlight in northern Europe during winter months meant that people had lower levels of vitamin D in their bodies, and therefore had difficulty absorbing calcium. Milk solved this problem by providing them with both calcium and some vitamin D.

Thomas says the comparison of the fossil DNA and present-day European genes provides a before-and-after snapshot that provides “the first ever direct evidence that humans have changed in response to natural selection."

From NewScientist