The rapid ascent of man: how the human races are evolving apart

The rapid ascent of man: how the human races are evolving apart

By DAVID DERBYSHIRE - More by this author » Last updated at 11:24am on 11th December 2007 Comments (3)

Humans are evolving at a faster rate than at any time in history, according to a study. Scientists say the speed of natural selection has accelerated so much that within a few generations we will have evolved resistance to diseases such as diabetes and malaria.

Instead of people from different parts of the world becoming more alike over time, they have actually been diverging, the study suggests.

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Genetic change: We are adapting faster than ever

Dr Henry Harpending, a professor of anthropology at the University of Utah who led the study, looked for clues about the speed of evolution in the DNA of 270 people from around the world.

The research showed that the population explosion since the Ice Age 10,000 years ago had accelerated the rate of genetic change.

"We aren't the same as people even 1,000 or 2,000 years ago," he told the journal Proceedings of the National Academy of Sciences.

"The dogma has been these are cultural fluctuations, but almost any temperament trait you look at is under strong genetic influence.

"Human races are evolving away from each other. Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin.

"We are getting less alike, not merging into a single, mixed humanity."

The study looked for genetic evidence of natural selection - the evolution of favourable gene mutations - during the past 80,000 years by analysing DNA from northern Europe, China, Japan and Africa's Yoruba tribe.

The Europeans were mostly represented by data from Utah Mormons. It looked at genetic variations called single nucleotide polymorphisms.

These are mutations that appear in DNA and if they are favourable, can spread quickly through natural selection.

The rate of evolution increased 40,000 years ago - after modern humans had left Africa and were colonising the world - and sped up even more when agriculture was developed 12,000 years ago.

These changes included the emergence of paler skin in Europeans to cope with the lack of sunlight in northern climes, and the spread of a gene that allows adults to drink milk without being ill.

Today, that gene is common in Europeans, but rare in Africans and Chinese.

Although the study found growing differences between races, it does not take into account mass migrations of the past 100 years which have brought together people from parts of the world that were once isolated.

Dr Harpending said differences between races "cannot be used to justify discrimination".

"People have rights and should have opportunities whatever their group," he said.

Co-author Dr John Hawks from the University of Wisconsin, said people were evolving resistance to diseases.

"If you suddenly take hunter-gatherers and give them a diet of corn, they frequently get diabetes. We're still adapting to that.

"Several new genes we see spreading through the population are involved with helping us prosper with high-carbohydrate diet," he said.

There are now more than two dozen genetic changes linked to malaria resistance, including an entirely new blood type known as the Duffy blood type.

Another recently discovered gene, CCR5, originated about 4,000 years ago and now exists in about 10 per cent of the European population.

It was discovered recently because it makes people resistant to HIV/Aids. But its original value might have come from obstructing smallpox, Dr Hawks said.