Original Homo sapiens could only digest lactose in milk until age-5.
But around around 10,000 B.C. a genetic mutation appeared, allowing many — including me — to enjoy lactose milk products their entire lives.
read more on Slate – The Most Spectacular Mutation in Recent Human History
In fact I use chocolate milk as a sports recovery drink. LOVE IT. 🙂
Cheers to Peter and Warren for the link.

Many people who have problems with regular pasteurized milk, do just fine with raw milk. Despite its bad stigma, raw milk from reputable sources is quite safe.