exception: temperate to tropics)—it is Mexicans and people further south who are coming into the US, not Canadians and Eskimos. So Trump is erecting a barrier against Darlington’s Rule—migration is always tropics outward. Africa is the center of the tropics in the entire globe. Before that it was part of Gondwanaland (Africa, South America, Antarctic) but it was the center of that super-continent, and therefore most tropical section, so Darlington’s rule held back then, as we know from fossils. BTW it is striking that there is strong evidence that selection from parasites has been increasing over the past 40,000 years with an acceleration of positive selection to a striking degree—before agriculture and animal husbandry which added further acceleration associated with orders of magnitude (5 Or 6) increases in density. There are “signatures” that genes show of recent strong positive selection, basically comparing neutral sites (change in DNA has no effect on structure of associated protein) with non- neutral sites and seeing if the latter evolve while the former show a random walk. And what are the chief “selected variants”? Parasite-resistant genes. Now these are automatically selected when density increases because parasites LOVE density--consider people packed in a room breathing on each other, or water-born parasites traveling quickly to others, or vector-borne parasites, e.g. malaria--if one in ten humans are sick but widely dispersed a mosquito biting the sick person rarely passes on the Plasmodium but if dense, every tenth person gives it to the mosquito who quickly passes it on Likewise parasites like mobility--which increases density of contacts--so Haitians acquired HIV-1 because their middle class served as the middle class of emerging French-speaking African nations with high HIV, and they brought back the disease with them when they HOUSE_OVERSIGHT_025144