Tue, Sep 09, 2008
HUMANS ARE still busily evolving under the influence of natural selection, studies have shown.
So far the changes have had little impact, since homo sapiens has only been on the planet for around 100,000 years.
But a million years from now there might be a lot more variation between people's genes, experts believe.
New evidence of the way the human genome is being shaped has emerged from two major pieces of research.
One, the HapMap Project, compared four large populations from around the world.
The other, the 1,000 Genomes Project, aims to sequence the genetic blueprint of 1,000 individuals.
Genetics expert Prof Gil McVean from Oxford University spoke about the studies yesterday at the British Association Festival of Science.
Speaking at the University of Liverpool, he said: "We're beginning to understand that the human genome is an incredibly dynamic object.
"It's not like everyone has the same three billion letters . The key insight is that in a lot of the variation that we see there's evidence that it's been shaped by natural selection.
"The differences between people and peoples do seem to be influenced by their environment ... Humans are still very much evolving."
The effects of infection, climate and diet could all influence the genetic make-up of new generations.
One example was the way Europeans and some African tribes had acquired an ability to digest milk through a particular genetic mutation, said Prof McVean. Other people remained lactose intolerant and unable to consume dairy products without getting ill.
A mutation that caused resistance to malaria in sub-Saharan Africans was another instance of evolution at work.
Generally there was evidence of genes emerging that could break down environmental toxins. Some of these might be adaptations to modern influences such as urban pollution, Prof McVean said.
"I could well imagine that that selection is coming in from new directions."
Despite these effects, humans were still one of the least-varied animals on the planet, Prof McVean said. Gut bacteria were 50 times more genetically variable than humans.
Humans had only evolved recently - around 100,000 years ago - and everyone alive today was descended from a small group of individuals, the professor added.
"In a million years we might be just as variable as other species," he said. - ( PA )
© 2008 The Irish Times