Toward a Unified Theory of Black America tells the story of Roland G. Fryer Jr., a 27-year-old assistant professor of economics at Harvard — who happens to be black. Naturally, this allows him the liberty to tackle racial issues — including some unusual theories:
Fryer’s notion that there might be a genetic predisposition at work was heightened when he came across a period illustration that seemed to show a slave trader in Africa licking the face of a prospective slave. The ocean voyage from Africa to America was so gruesome that as many as 15 percent of the Africans died en route, mainly from illnesses that led to dehydration. A person with a higher capacity for salt retention might also retain more water and thus increase his chance of surviving.So it may have been that a slave trader would try to select, with a lick to the cheek, the ”saltier” Africans. Whether selected by the slavers or by nature, the Africans who did manage to survive the voyage — and who then formed the gene pool of modern African-Americans — may have been disproportionately marked by hypertension.