on strange fruit

'I am inherently gloomy about the prospect of Africa. All our social policies are based on the fact that their intelligence is the same as ours - whereas all the testing says not really.'

So claimed the Nobel Laureate, and co-discoverer of the structure of DNA, James Watson in a controversial interview in the Sunday Times last October. Censure was swift and universal. The Federation of American Scientists condemned Watson for choosing 'to use his unique stature to promote personal prejudices that are racist, vicious and unsupported by science'. London's Science Museum, at which Watson was to have delivered a lecture, cancelled his appearance, claiming that he had gone 'beyond the point of acceptable debate'. New York's Cold Spring Harbor Laboratory, of which he was director, not only 'vehemently' disowned Watson's remarks but also forced him to resign.

The row over Watson's comments shows all that is wrong with the current debate about race. On the one hand, Watson got his facts in a double helix. There are certainly real genetic differences between human populations, the scientific study of which can help unravel the roots of disease, develop new medicines, unpick the details of deep human history - and perhaps even tell us something about the nature of intelligence. The concept of 'race', however, is a crude, and unscientific, tool through which to understand such genetic differences.

On the other hand, implicit in much of the outrage over Watson was the belief that certain views cannot be expressed, because they are politically unpalatable. That, too, is a deeply unscientific way of looking at the world. Race is a legitimate area for scientific inquiry. Watson had every right to express his opinion even if that opinion was factually wrong, morally suspect and politically offensive. That is the essence of scientific debate.

For 20 years I have been exploring the idea of race as a biologist, a historian and an antiracist activist. But two development over the past decade made me realise that I needed to rethink my attitudes to human differences.

First the idea of race has returned in a big way to scientific research and medical practice. Where once the idea of race was a scientific embarrassment, with most scientists dismissing racial differences as merely skin deep, now it is becoming central to much scientific debate. Where once only the lunatic fringe embraced racial ideas, now they have become the currency of distinguished, mainstream thinkers.

The US government, for instance, has licensed a heart drug to be used only on African Americans. In a follow-up to the Human Genome Project, geneticists have launched an international study to map genetic differences between races to help provide data for treating diseases. Anthropologists have developed software to determine an individual's race from the shape of his skull. A genetic study from respected researchers has claimed that Jews are more intelligent because their history of moneylending and other financial occupations has favoured genes associated with cleverness. Another suggests that white Britons are genetically distinct and can trace their ancestry back to a few hundred Stone Age hunters who lived here some 14,000 years ago. And so on.

In genetics, anthropology, psychology and medicine the use of racial categories is becoming the norm in both research and practice. For Steven Pinker 'the most dangerous idea of the next decade' will be the notion that races 'may differ genetically in their average talents and temperaments'. Dangerous not because it is a myth but because it is scientifically true but politically inconvenient.

I realised, therefore, that we needed to look again at the science of race in the wake of the new knowledge created by the Human Genome Project. The conclusions I came to were surprising. Race, I affirmed, is not a biological reality but something humans create socially. But it is precisely because it is a social category that race is so important in scientific and medical research. Getting our heads around this paradox will be crucial for the health both of scientific research and social harmony.

The second change that has taken place is equally paradoxical. For all the vitriol directed at the likes of James Watson, racial talk today is likely to come out of the mouths of liberal antiracists as of reactionary racial scientists. The affirmation of difference, which once was at the heart of racial science, has become a key plank of the antiracist outlook. We're All Multiculturalists Now observes the American sociologist Nathan Glazer in the title of a book. And indeed we are. The celebration of difference, respect for pluralism, avowal of identity politics - these have come to be regarded as the hallmarks of a progressive, antiracist outlook and as the foundation of modern liberal democracies. The old arguments about race have become recycled through new ideas about culture and identity. And these ideas can crop up in unexpected places. The current mania for genealogy, for instance, is helping rehabilitate racial ideas about human differences. So, surprisingly, is the debate about the Elgin Marbles and the idea of 'cultural ownership' expressed through the campaign for the repatriation of the Marbles.

Liberal antiracism has not only helped resurrect racial thinking. It has also become increasingly hostile to traditional notions of science, knowledge and freedom of thought - as the Watson row revealed. And this is perhaps the most paradoxical aspect of the new race debate - that in challenging the irrationality of racial science, liberal antiracists have become so irrational themselves.

Strange Fruit challenges both sides of the race debate. There are three broad parts to my argument. First, I re-examine the meaning of race as a scientific category - and the paradox that it is precisely because it is a social category that it may be useful in scientific and medical research. Second I look historically at the rise and fall of the idea of race, and its sublimation into the idea of culture. And third, the book explores at the contemporary clash between claims of scientific rationality and cultural identity and shows how much modern liberal thinking has been infected by a racial view of the world.

Race is not a rational, scientific category. Liberal antiracism has become an irrational, anti-scientific philosophy that paradoxically keeps the racial pot bubbling. The challenge we face is to confront racial thinking while defending scientific rationality and the Enlightenment idea of common values. The aim of Strange Fruit is to do just that.