Large-scale genome studies reveal evolution in action
9 September 2008
Scientists have known for some time that there is a significant amount of genetic variation between individual people, and that this contributes to how we look and the diseases that we are likely to develop. Recent advances such as the International HapMap Project and most recently the 1000 Genomes Project have provided scientists with the tools to explore this variation and understand how it arises.
Recent research published by Professor McVean and colleagues at the University of Oxford showed that certain types of mutation occur in hotspots across the human genome, partly arising due to a process known as recombination, which is essential for accurately copying our genome from mother to child.
“The genome is an incredibly dynamic object,” says Professor McVean. “It’s not like everyone has the same three billion letters. There’s a lot of rearrangement and shuffling and duplication and loss, and that’s all contributing to how we look and the diseases we’re going to get.”
According to Professor McVean, the key insight to come out of recent studies is that the majority of our genetic variation is caused by natural selection processes, rather than through random mutation: the differences that we see between people and different populations appear to be influenced by our environment, for example, diet, disease or physical environment.
The research has allowed scientists to address the key question of whether we are still evolving, or whether evolution has “stalled” in humans.
“In order to have evolution, you need to have a dynamic, shifting environment and you need processes generating variation,” says Professor McVean. “Those two things are very much still happening and as a consequence humans are still evolving.”
However, he says, humans are still amongst the least varied species on the planet. The bacteria that live in our gut are around 50 times more variable at the genetic level than humans, and the HIV-1 virus 500 more variable.
“There are only a very few things which are less variable than us: one is gonorrhoea and one of them tuberculosis.”
Image: Fiona Pragoff; Wellcome Images