professor Richard Lynn said the Scots average IQ of 97 was well below the England and Wales average of 100.5 and on a par with the Republic of Ireland. London and the south-east of England scored top in the UK, with an average IQ of 102.
Scotland - when split from the rest of the UK - comes two-thirds down the table of European average intelligence, beating Russia by one point and France by three.
But Prof Lynn, a lecturer at the University of Ulster, said he was not surprised by the poor Scots showing. He blamed the centuries-old tradition of Scots seeking their fortune south of the Border or overseas for a literal brain drain.
Prof Lynn said: "I believe this has been caused by selective migration. Over the course of two centuries, there has been a trend for more intelligent Scots to migrate to London and beyond, to New Zealand, Australia, the United States and Canada.
It wasn't a serious claim, it's marginal if anything. But white Welsh people aren't dumb, sorry to disappoint you. They score much higher than many ethnic groups around the world