Watson was to arrive Wednesday in London to promote a new book. His remarks in an interview published in The Sunday Times have sparked condemnation from politicians, and the Equality and Human Rights Commission is examining the interview.
"All our social policies are based on the fact that their intelligence is the same as ours -- whereas all the testing says not really," Watson told the Times.
Watson, working with British scientist Francis Crick, unraveled the structure of the DNA molecule in the 1950s at Cambridge University. Watson and Crick -- with Maurice Wilkins of Kings College in London, who also contributed to the effort -- were awarded the Nobel Prize for Medicine in 1962.
Watson said in the interview he opposes color-based discrimination because "there are many people of color who are very talented." But he said human groups separated geographically for thousands of years may have evolved different levels of intelligence.