| > social darwinism There is none of that in my comment. > I think you're missing why milk is useful though. ? I was saying it is useful, and therefore I expect Homo sapiens would adapt to it. After writing the GP I was told that humans, and some or all mammals, have a gene that disables lactose tolerance when they reach the stage of life where they no longer need milk. A miniority of humans have a mutation that stops that process, making them lactose-tolerent. Why haven't we evolved to consume milk lifelong, given its obvious advantages (or why have we evolved to become lactose-intolerent past early childhood)? A guess: Obviously milk consumption is inherited from mammal ancestors. That provides plenty of time (66 million years +) and population to evolve lifelong lactose digestion. But other mammals don't have much need for that adaptation - for the most part, they can't figure out obtaining milk from another species as a regular food source. Human ancestors didn't figure out tool use until 2.6-3.3 million years ago; would we have figured it out then? My guess is that it required domestication of animals ~12 thousand years ago before non-childhood milk consumption was commonplace. 12,000 years isn't much time to evolve much. |