But in us, the neo-Darwinian mechanism seems logjammed. Some genetic variants are being lost, as small tribal groups continue to die out; and others are constantly gained by mutations, some of which persist. There are fluctuations: genes that confer resistance to Aids are gaining ground in Africa, for instance, while Kenyans are currently breeding faster than Italians, so any genetic variants that are peculiar to either group must be increasing or falling. But the permanent losses of genes through extinction of minorities are small compared to the whole pool, and while the particular genes of Kenyans may wax in one century, they may wane in another. Most importantly, there is no consistent pressure to push our gene pool in any particular direction. Nobel prize-winners and professional basketball players are lauded, but do not typically leave more offspring than the ordinary Joe. Infant mortality is still high in some societies but, in genetic terms, it strikes randomly because the poor are not genetically distinct.