what is normal? not Milk! Evidence of Evolution in Modern Humans

Zac Eckstein wrote:Something that Europeans and their descendants do that you might not realise seems downright bizarre to the rest of the world is that we like to drink cool glasses of that white stuff that comes out from under a cow. That's because most of the non-white population of the world -- 50 percent of Mediterraneans, 95 percent of Asians, and close to 100 percent of Native Americans -- are lactose intolerant. On the other hand, 90 percent of Europeans can drink milk just fine. So why whitey? Simply, early Europeans spent more time around cows.

http://abcnews.go.com/Technology/story?id=8439522

Humans, like every other mammal, were never designed to drink milk past infancy. Normal people (and considering the global statistics, it's the lactose intolerant who are the normal people) lose the ability to digest milk at around 5 years old. That's when we stop producing the enzyme lactase, which breaks down the milk sugars known as lactose. Without that, the lactose in milk just goes straight to our colon and reinvents itself as the Hershey squirts.

But after white Europeans and cultures around the Middle East domesticated cattle around 7,500 years ago, they started dabbling in drinking their milk. Those few who were able to tolerate it had an evolutionary advantage, having access to an abundant new source of protein and vitamin D. Since those who drank their milk grew big and strong, the ability to digest it spread around cattle farming communities until most people who spent a lot of time around cows grew to enjoy it without running to whatever passed for a bathroom back then.

For the rest of the world who preferred to obtain their nutrition in ways that didn't involve sucking on a cow's tits, their lactose intolerance remained just as it was. So if you've enjoyed some cheese recently, you know who to thank.



Read more: http://www.cracked.com/article_20929_5-insane-ways-animals-changed-course-humanity_p2.html#ixzz2wN8PmFHI

Ben_Reilly wrote:Amazing! Think of the lives that have been prolonged by the ability digest cow's milk and the availability of it. Truly an evolutionary benefit; I imagine those who were unable to digest it were left at a disadvantage to those who were.

Very much like Lenski's experiment, when you think about it -- the evolution of the ability to survive on something that was not a viable source of food before.