Excerpt from United States Senate document #264:
"It is bad news to learn from our leading authorities that 99 percent of the American people are deficient in these minerals, and that a marked deficiency in any one or more of the important minerals actually results in disease. Any upset of the balance, any considerable lack of one or another element, however microscopic the body requirement may be, and we sicken, suffer, shorten our lives."
Over time certain groups of people have evolved to living beside animals to utilize their bounty. Those who didn't take well to the animal diet died earlier.
Probably why some groups of people don't tolerate milk as well as others