Milk is the Proof

Lactose tolerance gene proves Natural Selection in humans:

"In a recent paper by Dr. Sarah Tishkoff with the University of Maryland, and others titled 'Convergent adaptation of human lactase persistence in Africa and Europe', they describe the results of work collecting and analyzing several gene variants that are the key to the ability for adults to drink milk.

In most people, the ability to digest lactose, the main carbohydrate in milk, declines rapidly after weaning. It is caused by the decrease in production of an enzyme called lactase-phlorizin hydrolase (LPH). LPH breaks down lactose into glucose and galactose, sugars that are easily absorbed in the bloodstream and provide energy."