Watson makes humiliating return to US after row over race comments

James Watson, the veteran Nobel scientist who helped to unravel the structure of DNA in 1953, cancelled his book tour in Britain and returned home to the United States yesterday after his research institute suspended him for his comments about the intelligence of Africans.

Cold Spring Harbor Labor-atory in New York said that its board of trustees had decided to suspend Dr Watson from his administrative duties as Chancellor pending further investigations because of Dr Watson's comments, published in a Sunday newspaper in Britain, suggesting that Africans were less intelligent than white westerners.

Dr Watson hosted a reception on Thursday night at the Royal Society to celebrate the publication of his new book, Avoid Boring People, and was expected to follow it with a book-signing yesterday in London and public engagements next week in Oxford, Cambridge, Bristol, Newcastle and Edinburgh.

However, after a decision by the Science Museum in London to cancel a public talk planned for Friday evening, Bristol and Edinburgh followed suit. It was after Cold Spring Harbor issued its statement in the early hours of yesterday morning that Dr Watson decided to return home rather than continue with what was left of his book tour.

"Dr Watson felt that he needed to go back to the States. He wanted to fly home this morning to have discussions with Cold Spring Harbor Laboratory," said Kate Farquhar-Thomson, head of publicity at Oxford University Press, which is publishing his book.

"I found out that Dr Watson was leaving about 8am this morning when I spoke to him as he and his wife, Elizabeth, checked out of Claridges Hotel in central London. Unfortunately, this means that I am going to have to cancel all the plans for his UK tour."

Dr Watson's comments in a long interview with a former student, Charlotte Hunt-Grubbe, who now works for the Sunday Times, astounded colleagues and caused a public outcry. He said he was inherently gloomy about the prospects for 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".

In an article for The Independent yesterday, Dr Watson apologised for any offence he may have caused. He also said at the Royal Society that he was "bewildered" by the quotes attributed to him and that he had "no memory" of ever having made them – although he did not deny that he could have said them.

Ken Livingstone, the Mayor of London, attacked Dr Watson, saying that the comments were racist propaganda masquerading as scientific fact. "Such discredited racist theories seek to establish a genetically based racial hierarchy of the human race and have been condemned by leading scientists throughout the world," Mr Livingstone said.

"Such views are not welcome in a city like London, a diverse city whose very success demonstrates the racist and nonsensical nature of Dr Watson's comments," he said.

The Science Museum said it had decided to ban Dr Watson because his comments went beyond acceptable debate. A day later, the Bristol Cultural Development Partnership, which was due to host a public meeting with Dr Watson next week, decided that it too had to abandon his talk. "While we are a festival that encourages debate, it is clear that James Watson's opinions were unacceptably provocative," a spokesman said.

Leading academics denounced the decisions to ban Dr Watson, arguing that academic freedom of speech, and even thought, was at stake. "It's outrageous to ban someone based on newspaper reports of their views," said Professor Colin Blakemore, chief executive of the Medical Research Council and a professor of neuroscience at Oxford University.

"Jim Watson is well known for being provocative and politically incorrect. But it would be a sad world if such a distinguished scientist was silenced because of his more unpalatable views."

Professor Richard Dawkins, who was due to conduct a public interview with Dr Watson next week in Oxford, said that if Dr Watson is wrong he will be wrong scientifically, not ethically, and it is a scientific argument, not an ethical one, that will demonstrate his error.

"What is ethically wrong is the hounding, by what can only be described as an illiberal and intolerant 'thought police', of one of the most distinguished scientists of our time, out of the Science Museum, and maybe even out of the laboratory that [he] has devoted much of his life to building up a world-class reputation," Professor Dawkins said.

One of Dr Watson's greatest academic achievements was to take over the running of Cold Spring Harbor Laboratory in the 1960s and establish it as one of the world's greatest centres for research into molecular biology.

Other scientists, however, deplored his comments, arguing that they have no scientific basis. Craig Venter, who pioneered the decoding of the human genome, said: "There is no basis in scientific fact or in the human genetic code for the notion that skin colour will be predictive of intelligence."