On Bush's intelligence farther down here(*1): it's only opinion, of course, but it's educated opinion talking. Running a country takes 'sophistication' (classical sense); Bush's is 'frat boy'. That Bush has been elected president at all -twice no less, does not speak well for the sophistication of the American voter.

July 28, 2006 Science Magazine

The Anglo-Saxons who invaded Britain from northern Germany in the early 5th century C.E. and ruled over England for 600 years left a huge genetic imprint. Y chromosome studies show that they contributed up to 72% of the modern English gene pool.
   How did they do it? Native Britons numbered about 2 million in the 5th century, so to sweep the gene pool, the Anglo-Saxons would have had to number about 500,000--far more than suggested by archaeological and historical evidence.
   Instead, the Anglo-Saxons leveraged their DNA by ruling as an elite and separate group whose favored status allowed them to have more offspring than the Britons, claims a team led by geneticist Mark Thomas of University College London.

Anglo-Saxon helmet, from 7th century east Anglia.

The team used computer simulations that varied the number of invaders, the rate of intermarriage, and the postulated reproductive advantage. For example, even if the invaders were only 5% of the population, their Y chromosomes would reach the 50% mark within 15 generations if they were 1.4 times as likely as the locals to reproduce and the intermarriage rate was 7%. By keeping the intermarriage rate low, the Anglo-Saxons preserved their elite status and reproductive advantage.
   Thomas and colleagues note that their conclusions, published online 19 July in the Proceedings of the Royal Society B, are consistent with old laws that gave Anglo-Saxons higher social and economic status. "This is an exciting new contribution," says Alex Bentley, an anthropologist at the University of Durham, U.K. It shows that "culture has had real, measurable effects on human genetic history."

July 28, 2006 Science Magazine

In terms of intellect, John Quincy Adams, the sixth U.S. president, is the chief commander in chief, according to a new study that estimates the intelligence quotients (IQs) of all 43 U.S. presidents.
   For the rankings, psychologist Dean Simonton of the University of California, Davis, who does research on intellect and leadership, drew on studies by other researchers as well as history. Sources included IQ estimates that were based on the ages at which presidents reached intellectual milestones such as learning to read, accounts about their intellectual curiosity, and descriptions of the leaders' personality traits. Based on the descriptions, Simonton created anonymous profiles of all the presidents and asked a panel of research assistants to score each on traits associated with intelligence, including curiosity, insightfulness, and inventiveness.

Two extremes--Adams (left) and Harding.
   John Quincy Adams's IQ was estimated at about 170. Other smarty-pants include Thomas Jefferson, John F. Kennedy, and Bill Clinton, Simonton reports in the August issue of Political Psychology. And what of the current leader of the United States? George W. Bush's IQ score is probably about 125, which puts him in the upper range of college graduates but low among presidents. Warren Harding--who "by his own admission was not smart enough to be president," Simonton says--was the only 20th century president to get a lower estimate. Such rankings are imprecise given the gaps in the data, says Douglas Detterman, an intelligence researcher at Case Western Reserve University in Cleveland, Ohio. Even so, he says, Simonton's approach seems reasonable.