Last Sunday I was trying to browse the web in a hotel room in Beijing. Try as I might, I could not find the BBC news site. It reminded me that China, a country that I admire hugely, is still on a long march towards open expression and debate.

I am now in Singapore and have learnt from erroneous reports that James Watson, Nobel laureate, co-discoverer of the structure of DNA and one of the most influential scientists of the 20th century, had advocated discrimination against blacks in an interview in this newspaper.

Watson’s discoveries have led to immense and still-growing benefits to humanity. We should all be grateful to him for his fight to prevent the patenting and commercialisation of information about human genes. He works energetically and selflessly to convey the wonder of science to the public, including to underprivileged groups. And he is passionate in his support for research aimed at eradicating schizophrenia, the scourge suffered by his son Rufus.

I have known Jim for 20 years. I love his company and his zest for life. I’m proud to be a friend and yet to be free to object to some of the things he says. He is deliberately provocative, using outrageous comments as a conversational device - a way of testing the opinions of others.

When I heard that the Science Museum had cancelled a public lecture that Jim was due to give last Friday, I imagined that he must really have gone over the top. But what he was reported to have said is that he was “inherently gloomy about the prospect of Africa” because “all our social policies are based on the fact that their intelligence is the same as ours - whereas all the testing says not really”.

What he has written on this subject is even more measured: “There is no firm reason to anticipate that the intellectual capacities of peoples geographically separated in their evolution should prove to have evolved identically. Our wanting to reserve equal powers of reason as some universal heritage of humanity will not be enough to make it so.” I take it that Jim objects to positive discrimination on the basis of colour. But he does not argue that people (black or not) should be discriminated against on the basis of IQ.

The present outcry reminds me of the furore that followed a lecture by Roger Bannister, the legendary four-minute miler and distinguished neurologist, in 1995. He said he was “prepared to risk political incorrectness by drawing attention to the seemingly obvious but understressed fact that black sprinters and black athletes in general all seem to have certain natural anatomical advantages”.

At the Seoul Olympics in 1988, male runners from Kenya won the 800m, 1500m and 5,000m, and the 3,000m steeplechase. Based on population size the likelihood of this achievement is 1 in 1.6 billion. The fact that black athletes do disproportionately well is undeniable. Yet even though Bannister was talking about black superiority, he still provoked fierce criticism.

Whatever Watson actually said about race and intelligence, he should not have been silenced. I am sad that the Science Museum cancelled his lecture. I should have liked to be there, to challenge him to provide the evidence for his views.

There will be some who misinterpret and misuse Watson’s alleged opinions. But we should be grateful to live in a society that allows individuals to air their views and is then capable of rejecting them.

Genetics is illuminating our understanding of humanity, like a spreading floodlight, and is revealing a host of undeniable inherited differences between individuals and between ethnic groups. Ashkenazi Jews are more prone to a variety of inherited medical conditions (but have higher average IQ than Caucasians, by the way). The incidence of inherited forms of diabetes, blood, hormone and kidney diseases varies dramatically around the world. Knowledge of these differences is vitally important for medical care.

The basic structure and organisation of the brain is also regulated genetically, so it is no surprise to discover that many brain disorders and mental health problems have a genetic component. However, I think that Jim puts too much faith in the likelihood that genetic variation accounts for all differences in human personality.

It is true some surveys have found that average IQ differs between ethnic groups. But the variation of IQ within each ethnic group is far greater than the average differences between them. Whatever IQ tells us about intelligence (and that is hotly contested), the results of these tests do not allow us to generalise about individual intelligence.

Moreover, there is ample evidence that intelligence (or whatever it is that IQ measures) can be hugely affected by experience. In a classic study in the 1980s, a team led by Sir Michael Rutter found that the IQ of children raised in Romanian orphanages was almost 40 points below average when they arrived in the UK for adoption at the age of two or less. Most of them made astounding progress in the following two years, climbing to an IQ comparable with British children adopted in-country.

There is a deeper issue here. Society should not base its morality on a denial of facts.

Even if it were true that intelligence is firmly inherited and distinctly different between racial groups, this could not justify discrimination of whites against blacks (or Chinese against Caucasians) - any more than poor Rufus Watson should be condemned for his schizophrenia.

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