Paul also studied the banned texts. He studied balancing equilibriums and Hardy-Weinburg; but alone at night, walking the dark halls of his own head, it was the trade-offs that fascinated him most. Paul was a young man who understood trade-offs.

He learned of the recently discovered Alzheimer’s gene, APOE4—a gene common throughout much of the world; and he learned theories about how deleterious genes grew to such high frequencies. Paul learned that although APOE4 caused Alzheimer’s, it also protected against the devastating cognitive consequences of early childhood malnutrition. The gene that destroys the mind at seventy, saves it at seven months. He learned that people with sickle cell trait are resistant to malaria; and heterozygotes for cystic fibrosis are less susceptible to cholera; and people with type A blood survived the plague at higher frequencies than other blood types, altering forever, in a single generation, the frequency of blood types in Europe. A process, some said, now being slow-motion mimicked by the gene CKR5 and HIV.

In his anthropology courses, Paul learned that all humans alive today could trace their ancestry back to Africa, to a time almost six thousand years ago when the whole of human diversity existed within a single small population. And there had been at least two dispersions out of Africa, his professors said, if not more—a genetic bottleneck in support of the Deluvian Flood Theory. But each culture had its own beliefs. Muslims called it Allah. Jews, Yahweh. The science journals were careful not to call it God anymore; but they spoke of an intelligent designer—an architect, lowercase “a.” Though in his heart of hearts, Paul figured it all amounted to the same thing.

Paul learned they’d scanned the brains of nuns, looking for the God spot, and couldn’t find it.