The lecture is entitled "Human evolution is over", and this is how the media have been framing Jones' findings, although he's not quite saying that the process has stopped completely. Rather, he says that several factors have led to a slow-down, most strikingly the huge fall in the number of fathers over the age of 50, particularly in Western societies:
“Every time there is a cell division, there is a chance of a mistake, a mutation, an error. For a 29-year old father [the mean age of reproduction in the West] there are around 300 divisions between the sperm that made him and the one he passes on – each one with an opportunity to make mistakes. For a 50-year-old father, the figure is well over a thousand. A drop in the number of older fathers will thus have a major effect on the rate of mutation.”Other factors are the increased life expectancy of humans, which has lowered the capacity for natural selection, and the sheer size of the human population:
"Humans are 10,000 times more common than we should be, according to the rules of the animal kingdom, and we have agriculture to thank for that. Without farming, the world population would probably have reached half a million by now – about the size of the population of Glasgow. Small populations which are isolated can evolve at random as genes are accidentally lost. World-wide, all populations are becoming connected and the opportunity for random change is dwindling. History is made in bed, but nowadays the beds are getting closer together. We are mixing into a global mass, and the future is brown."You can listen to a recording of Jones discussing this on the Today programme this morning.