Guardian Observer February 3, 2002

Is human evolution finally over?

By Robin McKie

For those who dream of a better life, science has bad news: this is the best it is going to get. Our species has reached its biological pinnacle and is no longer capable of changing.

That is the stark, controversial view of a group of biologists who believe a Western lifestyle now protects humanity from the forces that used to shape Homo sapiens.

'If you want to know what Utopia is like, just look around - this is it,' said Professor Steve Jones, of University College London, who is to present his argument at a Royal Society Edinburgh debate, 'Is Evolution Over?', next week. 'Things have simply stopped getting better, or worse, for our species.'

This view is controversial, however. Other scientists argue that mankind is still being influenced by the evolutionary forces that created the myriad species which have inhabited Earth over the past three billion years.

'If you had looked at Stone Age people in Europe a mere 50,000 years ago, you would assume the trend was for people to get bigger and stronger all the time,' said Prof Chris Stringer, of the Natural History Museum, London. 'Then, quite abruptly, these people were replaced by light, tall, highly intelligent people who arrived from Africa and took over the world. You simply cannot predict evolutionary events like this. Who knows where we are headed?'


According to Darwin's theory, individual animals best suited to their environments live longer and have more children, and so spread their genes through populations. This produces evolutionary changes. For example, hoofed animals with longer necks could reach the juiciest leaves on tall trees and therefore tended to eat well, live longer, and have more offspring. Eventually, they evolved into giraffes. Those with shorter necks died out.

Similar processes led to the evolution of mankind, but this has now stopped because virtually everybody's genes are making it to the next generation, not only those who are best adapted to their environments.

'Until recently, there were massive differences between individuals' lifespans and fecundity,' said Jones. 'In London, the death rate outstripped the birth rate for most of the city's history. If you look at graveyards from ancient to Victorian times, you can see that a half of all children died before adolescence, probably because they lacked genetic protection against disease. Now, children's chances of reaching the age of 25 have reached 98 per cent. Nothing is changing. We have reached stagnation.'



However, such arguments affect only the Western world - where food, hygiene and medical advances are keeping virtually every member of society alive and able to pass on their genes. In the developing world, no such protection exists.




However, other scientists believe evolutionary pressures are still taking their toll on humanity, despite the protection afforded by Western life. For example, the biologist Christopher Wills, of the University of California, San Diego, argues that ideas are now driving our evolution. 'There is a premium on sharpness of mind and the ability to accumulate money. Such people tend to have more children and have a better chance of survival,' he says. In other words, intellect - the defining characteristic of our species - is still driving our evolution.

This view is countered by Peter Ward, of the University of Washington in Seattle. In his book, Future Evolution, recently published in the US by Henry Holt, Ward also argues that modern Western life protects people from the effects of evolution. 'I don't think we are going to see any changes - apart from ones we deliberately introduce ourselves, when we start to bio-engineer people, by introducing genes into their bodies, so they live longer or are stronger and healthier.'



Stringer disagrees, however. 'Evolution goes on all the time. You don't have to intervene. It is just that it is highly unpredictable. For example, brain size has decreased over the past 10,000 years. A similar reduction has also affected our physiques. We are punier and smaller-brained compared with our ancestors only a few millennia ago. So even though we might be influenced by evolution, that does not automatically mean an improvement in our lot.'

File Date: 02.05.02