London ? A prominent American scientist who set off an international furor with remarks about intelligence levels among blacks canceled a book tour of Britain and returned home Friday, after his employer suspended his administrative duties.

James Watson, 79, is chancellor of the prestigious Cold Spring Harbor Laboratory in New York. Late Thursday, the lab’s board said it had suspended Watson’s administrative responsibilities pending further deliberation.

Watson, who shared a Nobel Prize in 1962 for DNA research, apologized on Thursday.

“I am mortified about what has happened,” Watson said. “More importantly, I cannot understand how I could have said what I am quoted as having said.”

The trouble began after the Sunday Times Magazine of London quoted Watson as saying that he’s “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.”