As Fit as we will ever be: Evolution is over

Humans are as fit they will ever be according to geneticist Professor Steve Jones. In a lecture entitled 'Human Evolution is Over' delivered this week at University of College London in the United Kingdom, Professor Jones argue that there were three components to evolution - natural selection, mutation and random change.

As Professor Jones explained, "human social change often changes our genetic future," citing marriage patterns and contraception as examples. Although chemicals and radioactive pollution could alter genetics, one of the most important mutation triggers is advanced age in men.

This is because cell divisions in males increase with age, Professor Jones advised "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."

Professor Jones sees that another factor is the weakening of natural selection, adding "in ancient times half our children would have died by the age of 20. Now, in the Western world, 98% of them are surviving to 21."

Decreasing randomness is another contributing factor, Professor Jones believes, concluding "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."