Sunday, January 18, 2009

Why men are more intelligent than women

By Satoshi Kanazawa

The answer is:  They aren’t

The orthodoxy in intelligence research for the second half of the 20th century had been that men and women had the same average intelligence, but men had greater variance in their distribution than women.  Most geniuses were men, and most imbeciles were men, they said, while most women were in the normal range.  This conclusion, however, was manufactured out of political expediency.  Not wanting to discover, or a priori denying, any sex differences in intelligence, psychometricians simply deleted from the standardized IQ tests any item on which the performance of men and women differed.

More recently, however, especially since the turn of the millennium, there have been an increasing number of studies that cast doubt on this politically correct conclusion.  Studies with large representative national samples from Spain, Denmark, and the United States, as well as meta-analyses of a large number of published studies throughout the world, all conclude that men on average are slightly but significantly more intelligent than women, by about 3-5 IQ points.  So this has now become the new (albeit tentative) consensus in intelligence research.

However, these studies do not answer the ultimate evolutionary question of why men should be more intelligent than women.  General intelligence likely evolved as a domain-specific psychological mechanism to deal with evolutionary novelty.  However, unlike populations in different geographic parts of the world, men and women within a population have always faced the same level of evolutionary novelty throughout evolutionary history, because they have always migrated together.  If general intelligence is a function of the evolutionary novelty of the environment, why then are men on average slightly more intelligent than women?

My LSE colleague, Diane J. Reyniers, and I offer one possible explanation in our article, forthcoming in the American Journal of Psychology.  Psychometricians have known since the end of the 19th century that height is positively correlated with intelligence:  Taller people on average are more intelligent than shorter people.  And men in every human population are taller than women.  So one possibility is that men are more intelligent than women, not because they are men, but because they are taller.

Our analysis of a large representative American sample from the National Longitudinal Study of Adolescent Health shows that this is indeed the case.  In fact, once we control for height, women are slightly but significantly more intelligent than men.  Further controlling for health, physical attractiveness, age, race, education, and earnings does not alter this conclusion.  Height has exactly the same effect on intelligence for men and women:  Each inch in height increases the IQ by about .4 point.  The partial effect of height on intelligence is more than three times as strong as the partial effect of sex.

So it is not that men are more intelligent than women, but that taller people are more intelligent than shorter people, but net of height women are more intelligent than men.  Women who are 5’10” are on average more intelligent than men who are 5’10”, and women who are 5’5” are on average more intelligent than men who are 5’5”.  But, more importantly, people who are 5’10” are significantly more intelligent than people who are 5’5”, and most people who are 5’10” are men and most people who are 5’5” are women.

This conclusion simply leads to another question:  Why are taller people more intelligent than shorter people?  I’ll address this question in my next post.

Wednesday, January 14, 2009

Woman attacked in Scotland ‘because she sounded English’

Police treating incident as racially motivated

A young woman who comes from England originally has been viciously assaulted in a Scottish city centre in what police are treating as a racially motivated attack.

Lucy Newman, 22, who lived in Cheltenham as a child, claims her male attacker said “Get back to England” before punching her in the face. She was left with serious injuries after the attack last Saturday in Aberdeen.

Ms Newman, who was on a night out with a female friend, said she was hit so hard that she fell, hitting the pavement and fracturing her left cheekbone. The nerves in her eye have also been damaged.

“We had just left a club and were going to catch a bus,” said Ms Newman, a beauty therapist who has lived in Scotland for about 15 years.

“We noticed these two older guys alongside us . . . we carried on walking and then heard them saying something about the English, because I’m from England and I do have a twang with some of the things I say.

“He shouted something like, ‘Get back to England’. I turned round, not even thinking that he was speaking to me. I didn’t even get a chance to look at him properly and he just punched me in the face.”

Ms Newman, whose accent sounds Scottish, added: “A few things I say sound English. But no one has ever hit me because I am English.”

Her mother, Susan, 47, a trainee funeral director, said: “I can’t believe somebody, especially a man, could do something like this to such a lovely and quiet girl. She’s tiny, about 5ft 3in (1.6m) and weighs next to nothing.”

Grampian Police are appealing for witnesses. Sergeant David Forsyth said: “Whilst this is clearly a despicable act, it is unfortunately not uncommon for racially motivated incidents to take place. Very often these incidents occur during the evenings when alcohol has been consumed.

“Where sufficient evidence exists that an incident had some racial motivation to it, those responsible will be charged with a racial offence in addition to any other matter.”

There have been other incidents of low-level anti-Englishness over the years, particularly in rural areas, but overt violence is uncommon.

In 1999 Tina Warren, who ran a museum near Pitlochry, Perthshire, claimed her time in Scotland had been made a “living hell” by anti-English racists. She alleged that she met “vicious hostility”, received verbal abuse and her signs had been smashed.

A spate of anti-English racial attacks by Scots came in June 2006, during the football World Cup. In the most shocking incident, a seven-year-old boy wearing an England shirt was punched in the head in an Edinburgh park. Hugo Clapshaw, whose father is a New Zealander and whose mother is Scottish, was attacked by a man who shouted “This is Scotland, not f****** England” before running off. In another incident, a man from Leeds who had moved to Lanarkshire had three windows broken at his home after flying the St George’s Cross.

Aberdeen, which has been the focus of the international oil industry for more than 30 years, has a slightly lower rate of racial incidences than other Scottish cities. Nevertheless, the Aberdeen Racist Incidents Partnership found that there had been a rise in reported racist incidents in primary and secondary schools in recent years.

Lewis Macdonald, the Labour MSP for Aberdeen Central, said: “This is a very disappointing incident, given Aberdeen’s strong culture of welcoming people from all over Britain and the world. It’s a very cosmopolitan city.”

A Scottish Government spokesperson said: “Any assault, verbal or physical, which is borne out of prejudice is utterly abhorrent. Fortunately our police forces take racially aggravated crime very seriously and our courts are able to reflect the nature of aggravation when sentencing.”