In the New York Times, John Tierney  reports:
When men and women take personality tests, some of the old Mars -Venus stereotypes keep reappearing. On average, women are more cooperative, nurturing, cautious and emotionally responsive. Men tend to be more competitive, assertive, reckless and emotionally flat. Clear differences appear in early childhood and never disappear.
Whatâ€™s not clear is the origin of these differences. Evolutionary psychologists  contend that these are innate traits inherited from ancient hunters and gatherers. Another school of psychologists asserts that both sexesâ€™ personalities have been shaped by traditional social roles, and that personality differences will shrink as women spend less time nurturing children and more time in jobs outside the home.
To test these hypotheses, a series of research teams have repeatedly analyzed personality tests taken by men and women in more than 60 countries around the world. For evolutionary psychologists, the bad news is that the size of the gender gap in personality varies among cultures. For social-role psychologists, the bad news is that the variation is going in the wrong direction. It looks as if personality differences between men and women are smaller in traditional cultures like Indiaâ€™s or Zimbabweâ€™s than in the Netherlands or the United States. A husband and a stay-at-home wife in a patriarchal Botswanan clan seem to be more alike than a working couple in Denmark or France. The more Venus and Mars have equal rights and similar jobs, the more their personalities seem to diverge.
These findings are so counterintuitive that some researchers have argued they must be because of cross-cultural problems with the personality tests. But after crunching new data from 40,000 men and women on six continents, David P. Schmitt and his colleagues conclude that the trends are real. Dr. Schmitt, a psychologist at Bradley University in Illinois and the director of the International Sexuality Description Project, suggests that as wealthy modern societies level external barriers between women and men, some ancient internal differences are being revived.
The biggest changes recorded by the researchers involve the personalities of men, not women. Men in traditional agricultural societies and poorer countries seem more cautious and anxious, less assertive and less competitive than men in the most progressive and rich countries of Europe and North America.
To explain these differences, Dr. Schmitt and his collaborators from Austria and Estonia point to the hardships of life in poorer countries. They note that in some other species, environmental stress tends to disproportionately affect the larger sex and mute costly secondary sexual characteristics (like male birdsâ€™ displays of plumage). And, they say, there are examples of stress muting biological sex differences in humans. For instance, the average disparity in height between men and women isnâ€™t as pronounced in poor countries as it is in rich countries, because boysâ€™ growth is disproportionately stunted by stresses like malnutrition  and disease.
For my upcoming review of the remake of "The Women" with Meg Ryan, Annette Bening and the traditional all-female cast, I rented the 1939 George Cukor-directed original (based on the play by Clare Booth Luce), which is so good that my wife watched it three times over the weekend. It's the story of Park Avenue society ladies who can afford to indulge in every rococo frill of femininity. When all the ladies who lunch end up at a dude ranch in Reno for six weeks so they can qualify as Nevada residents and get quick divorces, their cook is a tough old cowgirl (played by Marjorie Main, who went on to star in the lucrative "Ma and Pa Kettle" comedies about a clan of hicks) who thinks the ultrafeminine New York women are silly and spoiled.
Ma and Pa Kettle both got a heap of farm chores to do, and don't have time, energy, or money to waste on, say, tiny purse dogs or playing Grand Theft Auto, so they might be more similar in important ways than a wealthy couple.
â€śIn some ways modern progressive cultures are returning us psychologically to our hunter-gatherer roots,â€ť he argues. â€śThat means high sociopolitical gender equality over all, but with men and women expressing predisposed interests in different domains. Removing the stresses of traditional agricultural societies could allow menâ€™s, and to a lesser extent womenâ€™s, more â€?naturalâ€™ personality traits to emerge.â€ť
I'm not a big fan of self-reported cross-cultural personality tests because you're always seeing oddities, such as Danes and Swedes showing up at opposite ends on some personality trait. What Freud called the narcissism of small differences can have a big impact on these tests, where people compare themselves to other people they know, not to people around the world. Moreover, the problems of translating text about emotions can throw monkey wrenches into the results.
Fortunately, there is some objective data on ... track and field! (And you were looking forward to a 3 year and 11 month respite until the next Olympics.)
But he notes that thereâ€™s already an intriguing trend reported for one trait â€” competitiveness â€” based on direct measures of male and female runners.
Competitive running makes a good case study because, to mix athletic metaphors, it has offered a level playing field to women the past two decades in the United States. Similar numbers of males and females run on high school and college teams and in road races. Female runners have been competing for equal shares of prize money and receiving nearly 50 percent more scholarship aid from Division I colleges than their male counterparts, according to the N.C.A.A .
But these social changes have not shrunk a gender gap among runners analyzed by Robert Deaner , a psychologist at Colgate University , who classifies runners as relatively fast if they keep close to the pace of the worldâ€™s best runners of their own sex. When Dr. Deaner looks at, say, the top 40 finishers of each sex in a race, he typically finds two to four times as many relatively fast male runners as relatively fast female runners.
This large gender gap has persisted for two decades in all kinds of races â€” high school and college meets, elite and nonelite road races â€” and it jibes with other studies reporting that male runners train harder and are more motivated by competition, Dr. Deaner says. This enduring â€śsex difference in competitiveness,â€ť he concludes, â€śmust be considered a genuine failure for the sociocultural conditions hypothesisâ€ť that the personality gap will shrink as new roles open for women.
(This gender gap is actually even bigger than the track results show because American male distance runners can't really compete with Kenyan men on the world class level, but there are fewer Kenyan women running, so American women would have more of a chance than American men at the 800m to 10000m distances.)
Clare Booth Luce said it well (hat tip to Christina Hoff Sommers ):
"It is time to leave the question of the role of women in society up to Mother Nature--a difficult lady to fool. You have only to give women the same opportunities as men, and you will soon find out what is or is not in their nature. What is in women's nature to do they will do, and you won't be able to stop them. But you will also find, and so will they, that what is not in their nature, even if they are given every opportunity, they will not do, and you won't be able to make them do it."