Evolution is a series of successful mistakes: errors made when copying genes, which – by allowing their carriers to run faster or to live on less food – mean they do better. Natural selection, as Darwin called this idea, comes from inherited differences in survival. It worked on us in the past – with some people better at dealing with diseases like malaria, or poisons such as alcohol – and, in time, it leads to new species (ourselves included).

The important word is differences; and they have disappeared. Now, almost every baby born in richer countries survives until they are grown up, but that is new; even in Shakespeare's time, only one in three did – and many who died young did so because their genes could not resist disease, cold, starvation. Now we almost all pass the Darwin exam, we will not become a new species. But although our bodies will not change, with luck our minds – unkind, greedy and angry as they too often are – will.

• Steve Jones's latest book, The Serpent's Promise, is published in May.