Dr James Watson, who won a Nobel Prize in 1962 for his part in discovering the structure of DNA, was due to speak at The British The Science Museum on Friday.
But the museum has cancelled the event, saying his views went "beyond the point of acceptable debate".
Dr Watson, currently director of the Cold Spring Harbor Laboratory (CSHL) in New York, has arrived in Britain to promote his latest book.
In an interview with The Sunday Times, the 79-year-old said 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".
He went on to say he hoped everyone was equal but that "people who have to deal with black employees find this is not true".
The scientist has courted controversy in the past, saying that a woman should have the right to abort her unborn child if tests could determine it would be homosexual.
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