I just saw a commercial for Lactaid, the milk that's been processed so those who are lactose-intolerant can process it easily. The thing that caught my eye about the commercial was the ethnicity of the three lovely ladies shown enjoying the milk.
Lactose-intolerance, or the inability to process the milk sugar lactose, is the norm throughout most of the world, this because it's been the norm through history for humans to stop using milk as a food source after weaning. The ability to digest lactose into adulthood is a modification in those populations where milk products continued to be a primary source of protein into adulthood, mainly populations in Northern Europe and some in East Africa.
The vast majority of people in the world--Asians, Native Americans, those of African descent--are lactose-intolerant (60% to 100% in those populations), while the rates of lactose intolerance in those of Northern European ancestry are as low as 2% to 5%.
Someone needs to tell the folks at Lactaid, because they're a bit confused. All three shiny, smiling women in their commercial were white.