“Are humans still evolving? In the vernacular sense of improving morally and intellectually – by cultural changes – I think so,” says Steven Pinker. “In the biological sense of changes in the gene pool, it’s impossible to say.” If pressed to come off the fence, however, the Harvard-based evolutionary biologist knows where he stands. “People, including me, would rather believe that significant human biological evolution stopped between 50,000 and 100,000 years ago, before the races diverged, which would ensure that racial and ethnic groups are biologically equivalent,” he says.

It’s an understandable position given the political implications of being wrong. And in one important sense Pinker is absolutely spot on: it’s very difficult, if not impossible, to observe human evolution in action. But saying it isn’t happening is an increasingly difficult position to defend scientifically. Recent discoveries show that we must reject the idea that human evolution stopped dead 50,000 years ago or more. In fact, there is every reason to believe that it is going on right now.

Take the discovery last year by Bruce Lahn of the University of Chicago of two genes involved in brain development that emerged in recent human history and swept quickly through the population. One, a version of a gene called microcephalin, arose between 14,000 and 60,000 years ago and is now carried by 70 per cent of people. The other, a variant of the ASPM gene, is as recent as 500 to 14,000 years old and is now carried by about a quarter of the global population.

No one yet knows the function of these genes, but Lahn’s …