Meanwhile, down on the Farm

Note Added in response to 2020 Twitter mob attack which attempts to misrepresent my views: This blog post discusses the firing of James Damore by Google. It was a sensation at the time in Silicon Valley and made national news. This post is primarily about the scientific content of Damore's memo. Initial media reports describing his memo were very misleading and few people made the effort to read what Damore actually wrote before attacking him. I happened to notice that the Stanford Medical School magazine had (by coincidence) just featured an article on some of the issues discussed by Damore. Whether (below) the Stanford neuroscientist Nirao Shah or the former President of the American Psychological Association Diane Halpern are correct or not about the science, it seems unfair to call Damore a crank if he is simply referencing (in good faith) results in the published scientific literature. The same kinds of results are presented in the article below, written for the alumni of Stanford Medical School.

In the second part of the post below I describe some recent survey results on individual preferences among mathematically gifted men and women who are part of a ~50 year longitudinal study -- they have been studied since childhood. I note specifically that differences in preferences between men and women are not necessarily biological in origin (we simply don't know): they could be the result of sexism in child rearing, schooling, postdoc training, etc.

However, the point is that the survey results are likely descriptive of how actual adult men and women think and feel, and may have implications for labor markets. This is NOT a discussion about ability differences between men and women (all the individuals in the study are mathematically gifted), but rather about preferences concerning life fulfillment, lifestyle, work-life balance, etc. And again, no causation is assumed -- the situation may be entirely due to sexism in society, with zero biological basis.

The Spring 2017 issue of the Stanford Medical School magazine has a special theme: Sex, Gender, and Medicine. I recommend the article excerpted below to journalists covering the Google Manifesto / James Damore firing. After reading it, they can decide for themselves whether his memo is based on established neuroscience or bro-pseudoscience.

Perhaps top Google executives will want to head down the road to Stanford for a refresher course in reality.

Stanford Neuroscience Professor Nirao Shah and Diane Halpern, past president of the American Psychological Association, would both make excellent expert witnesses in the Trial of the Century.

Two minds: The cognitive differences between men and women

... Nirao Shah decided in 1998 to study sex-based differences in the brain ... “I wanted to find and explore neural circuits that regulate specific behaviors,” says Shah, then a newly minted Caltech PhD who was beginning a postdoctoral fellowship at Columbia. So, he zeroed in on sex-associated behavioral differences in mating, parenting and aggression.

“These behaviors are essential for survival and propagation,” says Shah, MD, PhD, now a Stanford professor of psychiatry and behavioral sciences and of neurobiology. “They’re innate rather than learned — at least in animals — so the circuitry involved ought to be developmentally hard-wired into the brain. These circuits should differ depending on which sex you’re looking at.”

His plan was to learn what he could about the activity of genes tied to behaviors that differ between the sexes, then use that knowledge to help identify the neuronal circuits — clusters of nerve cells in close communication with one another — underlying those behaviors.

At the time, this was not a universally popular idea. The neuroscience community had largely considered any observed sex-associated differences in cognition and behavior in humans to be due to the effects of cultural influences. Animal researchers, for their part, seldom even bothered to use female rodents in their experiments, figuring that the cyclical variations in their reproductive hormones would introduce confounding variability into the search for fundamental neurological insights.

But over the past 15 years or so, there’s been a sea change as new technologies have generated a growing pile of evidence that there are inherent differences in how men’s and women’s brains are wired and how they work.

... There was too much data pointing to the biological basis of sex-based cognitive differences to ignore, Halpern says. For one thing, the animal-research findings resonated with sex-based differences ascribed to people. These findings continue to accrue. In a study of 34 rhesus monkeys, for example, males strongly preferred toys with wheels over plush toys, whereas females found plush toys likable. It would be tough to argue that the monkeys’ parents bought them sex-typed toys or that simian society encourages its male offspring to play more with trucks. A much more recent study established that boys and girls 9 to 17 months old — an age when children show few if any signs of recognizing either their own or other children’s sex — nonetheless show marked differences in their preference for stereotypically male versus stereotypically female toys.

Halpern and others have cataloged plenty of human behavioral differences. “These findings have all been replicated,” she says.

... “You see sex differences in spatial-visualization ability in 2- and 3-month-old infants,” Halpern says. Infant girls respond more readily to faces and begin talking earlier. Boys react earlier in infancy to experimentally induced perceptual discrepancies in their visual environment. In adulthood, women remain more oriented to faces, men to things.

All these measured differences are averages derived from pooling widely varying individual results. While statistically significant, the differences tend not to be gigantic. They are most noticeable at the extremes of a bell curve, rather than in the middle, where most people cluster. ...

See also Gender differences in preferences, choices, and outcomes: SMPY longitudinal study. These preference asymmetries are not necessarily determined by biology. They could be entirely due to societal influences. But nevertheless, they characterize the pool of human capital from which Google is trying to hire.

The recent SMPY paper below describes a group of mathematically gifted (top 1% ability) individuals who have been followed for 40 years. This is precisely the pool from which one would hope to draw STEM and technological leadership talent. There are 1037 men and 613 women in the study.

The figures show significant gender differences in life and career preferences, which affect choices and outcomes even after ability is controlled for. (Click for larger versions.) According to the results, SMPY men are more concerned with money, prestige, success, creating or inventing something with impact, etc. SMPY women prefer time and work flexibility, want to give back to the community, and are less comfortable advocating unpopular ideas. Some of these asymmetries are at the 0.5 SD level or greater. Here are three survey items with a ~ 0.4 SD or more asymmetry:

# Society should invest in my ideas because they are more important than those of other people.

# Discomforting others does not deter me from stating the facts.

# Receiving criticism from others does not inhibit me from expressing my thoughts.

I would guess that Silicon Valley entrepreneurs and leading technologists are typically about +2 SD on each of these items! One can directly estimate M/F ratios from these parameters ...

For example, if a typical male SV entrepreneur / tech leader is roughly +2SD on these traits whereas a female is +2.5SD, the population fraction would be 3:1 or 4:1 larger for males. This doesn't mean that the females who are > +2.5SD (in the female population) are ill-suited to the role (they may be as good as the men), just that there are fewer of them in the general population. I was shocked to see that even top Google leadership didn't understand this point that Damore tried to make in his memo.

A 6ft3 Asian-American guard (Jeremy Lin) might be just as good as other guards in the NBA, but the fraction of Asian-American males who are 6ft3 is smaller than for other groups, like African-Americans. Even if there were no discrimination against Asian players, you'd expect to see fewer (relative to base population) in the NBA due to the average height difference.

Sex Differences In The Adult Human Brain: UK Biobank data

Male brains exhibit larger variance across all morphological measures. (Don't tell Larry Summers! ;-)

Note, as far as I can tell the authors don't normalize the SD by mean value for each gender to obtain the typical percentage fluctuation (a dimensionless quantity). The male brain is about 10% larger and each of the subregions is roughly that much bigger as well. If you divide the larger male SD by the larger male mean for each morphology the effect is much smaller than tabulated in the second figure below.

Sex Differences In The Adult Human Brain: Evidence From 5,216 UK Biobank Participants

doi: https://doi.org/10.1101/123729

Sex differences in human brain structure and function are of substantial scientific interest because of sex-differential susceptibility to psychiatric disorders and because of the potential to explain sex differences in psychological traits. Males are known to have larger brain volumes, though the patterns of differences across brain subregions have typically only been examined in small, inconsistent studies. In addition, despite common findings of greater male variability in traits like intelligence, personality, and physical performance, variance differences in the brain have received little attention. Here we report the largest single-sample study of structural and functional sex differences in the human brain to date (2,750 female and 2,466 male participants aged 44-77 years). Males had higher cortical and sub-cortical volumes, cortical surface areas, and white matter diffusion directionality; females had thicker cortices and higher white matter tract complexity. Considerable overlap between the distributions for males and females was common, and subregional differences were smaller after accounting for global differences. There was generally greater male variance across structural measures. The modestly higher male score on two cognitive tests was partly mediated via structural differences. Functional connectome organization showed stronger connectivity for males in unimodal sensorimotor cortices, and stronger connectivity for females in the default mode network. This large-scale characterisation of neurobiological sex differences provides a foundation for attempts to understand the causes of sex differences in brain structure and function, and their associated psychological and psychiatric consequences.

2:1 faculty preference for women on STEM tenure track (PNAS)

The results described below suggest that faculty evaluators of STEM job applicants tend to favor women over men. Certainly, most departments receive strong incentives and signals from above to increase numbers of women and underrepresented minorities among their faculty. Women could still face obstacles at other points in their careers, such as during promotion or merit reviews, or in the competition for resources such as grant funding or lab space. Nevertheless, I think gender discrimination has decreased significantly during my adult life.

This article is also discussed in Nature. See also STEM, Gender, and Leaky Pipelines and Gender differences in preferences, choices, and outcomes. Earlier blog posts citing research by Ceci and Williams.

National hiring experiments reveal 2:1 faculty preference for women on STEM tenure track (PNAS)

Wendy M. Williams and Stephen J. Ceci

National randomized experiments and validation studies were conducted on 873 tenure-track faculty (439 male, 434 female) from biology, engineering, economics, and psychology at 371 universities/colleges from 50 US states and the District of Columbia. In the main experiment, 363 faculty members evaluated narrative summaries describing hypothetical female and male applicants for tenure-track assistant professorships who shared the same lifestyle (e.g., single without children, married with children). Applicants' profiles were systematically varied to disguise identically rated scholarship; profiles were counterbalanced by gender across faculty to enable between-faculty comparisons of hiring preferences for identically qualified women versus men. Results revealed a 2:1 preference for women by faculty of both genders across both math-intensive and non–math-intensive fields, with the single exception of male economists, who showed no gender preference. Results were replicated using weighted analyses to control for national sample characteristics. In follow-up experiments, 144 faculty evaluated competing applicants with differing lifestyles (e.g., divorced mother vs. married father), and 204 faculty compared same-gender candidates with children, but differing in whether they took 1-y-parental leaves in graduate school. Women preferred divorced mothers to married fathers; men preferred mothers who took leaves to mothers who did not. In two validation studies, 35 engineering faculty provided rankings using full curricula vitae instead of narratives, and 127 faculty rated one applicant rather than choosing from a mixed-gender group; the same preference for women was shown by faculty of both genders. These results suggest it is a propitious time for women launching careers in academic science. Messages to the contrary may discourage women from applying for STEM (science, technology, engineering, mathematics) tenure-track assistant professorships.

STEM, Gender, and Leaky Pipelines

Some interesting longitudinal results on female persistence through graduate school in STEM. Post-PhD there could still be a problem, but apparently this varies strongly by discipline. These results suggest that, overall, it is undergraduate representation that will determine the future gender ratio of the STEM professoriate.

The bachelor’s to Ph.D. STEM pipeline no longer leaks more women than men: a 30-year analysis

(Front. Psychol., 17 February 2015 | doi: 10.3389/fpsyg.2015.00037)

D. Miller and J. Wai

For decades, research and public discourse about gender and science have often assumed that women are more likely than men to “leak” from the science pipeline at multiple points after entering college. We used retrospective longitudinal methods to investigate how accurately this “leaky pipeline” metaphor has described the bachelor’s to Ph.D. transition in science, technology, engineering, and mathematics (STEM) fields in the U.S. since the 1970s. Among STEM bachelor’s degree earners in the 1970s and 1980s, women were less likely than men to later earn a STEM Ph.D. However, this gender difference closed in the 1990s. Qualitatively similar trends were found across STEM disciplines. The leaky pipeline metaphor therefore partially explains historical gender differences in the U.S., but no longer describes current gender differences in the bachelor’s to Ph.D. transition in STEM. The results help constrain theories about women’s underrepresentation in STEM. Overall, these results point to the need to understand gender differences at the bachelor’s level and below to understand women’s representation in STEM at the Ph.D. level and above. Consistent with trends at the bachelor’s level, women’s representation at the Ph.D. level has been recently declining for the first time in over 40 years.

... However, as reviewed earlier, the post-Ph.D. academic pipeline leaks more women than men only in some STEM fields such as life science, but surprisingly not the more male-dominated fields of physical science and engineering (Ceci et al., 2014). ...

Conclusion: Overall, these results and supporting literature point to the need to understand gender differences at the bachelor’s level and below to understand women’s representation in STEM at the Ph.D. level and above. Women’s representation in computer science, engineering, and physical science (pSTEM) fields has been decreasing at the bachelor’s level during the past decade. Our analyses indicate that women’s representation at the Ph.D. level is starting to follow suit by declining for the first time in over 40 years (Figure 2). This recent decline may also cause women’s gains at the assistant professor level and beyond to also slow down or reverse in the next few years. Fortunately, however, pathways for entering STEM are considerably diverse at the bachelor’s level and below. For instance, our prior research indicates that undergraduates who join STEM from a non-STEM field can substantially help the U.S. meet needs for more well-trained STEM graduates (Miller et al., under review). Addressing gender differences at the bachelor’s level could have potent effects at the Ph.D. level, especially now that women and men are equally likely to later earn STEM Ph.D.’s after the bachelor’s.

Gender trouble in the valley

This NYTimes article looks at the gender disparity in technology career success within the Stanford class of 1994.

NYTimes: In the history of American higher education, it is hard to top the luck and timing of the Stanford class of 1994, whose members arrived on campus barely aware of what an email was, and yet grew up to help teach the rest of the planet to shop, send money, find love and navigate an ever-expanding online universe. ...

I found this reader comment to be realistic -- it is consistent with my own experience both as a parent and as a startup founder.

tiddle nyc

I've been in tech field for some years now. Being a working mother, with two kids (one boy, one girl), this subject hits close to home.

When I first started, there were more women in the ranks than it is now. I never experienced any sexism or discrimination in workplace, nor did I ever feel pushed aside. But I have to say this to my fellow female peers, in order to get ahead, you have to stay in the field. Dropping out or even scaling back will not help, and you can't blame others for not entrusting you with high profile projects because you might not be here next week.

Naturally it helps to have a spouse who share chores and childrearing, rather than having the woman/mother/wife to have-it-all, but really do-it-all which is practically impossible. That's how we stay the course and allow a pathway for younger generations of female to move up the ranks.

Looking at my kids - and we raise them to have the same aspirations, ambitions, and aggressiveness - there is indeed certain nature-vs-nurture difference. Justified or not, my son is almost always over-confident in his ability in all situations whereas my daughter is more circumspect and tentative (even if she's more than capable). It takes a lot more encouragement to prompt my daughter to be aggressive, whereas my son naturally does it on his own. As I look around all those in fields like VC and startups, I see mirrors of how men and women behavior.

This article doesn't surprise me.

See also Gender differences in preferences, choices, and outcomes: SMPY longitudinal study. A longitudinal study of mathematically precocious men and women (SMPY) showed significant gender differences in life and career preferences:

... According to the results, SMPY men are more concerned with money, prestige, success, creating or inventing something with impact, etc. SMPY women prefer time and work flexibility, want to give back to the community, and are less comfortable advocating unpopular ideas. Some of these asymmetries are at the 0.5 SD level or greater. Here are three survey items with a ~ 0.4 SD or more asymmetry:

# Society should invest in my ideas because they are more important than those of other people.

# Discomforting others does not deter me from stating the facts.

# Receiving criticism from others does not inhibit me from expressing my thoughts.

I would guess that Silicon Valley entrepreneurs and leading technologists are typically about +2 SD on each of these items! One can directly estimate M/F ratios from these parameters ...

The anecdote below about serial entrepreneur David Sacks is amusing:

NYTimes: ... Mr. Sacks almost wasn't hired because of doubts that he could work well with others; during his job interview, he put the chief financial officer on notice that his own job would be totally different once Mr. Sacks arrived, Mr. Thiel remembered. But his lack of social grace became an asset, according to Mr. Thiel and other former colleagues. He did not waste time on meetings that seemed pointless, and he bluntly insisted that the engineers whittle an eight-page PayPal registration process down to one.

Everyone knew Mr. Sacks was politically conservative, but in the office, he was less bombastic. He had become a manager, he said in an interview, and did not want to hurt the cohesion of his team. But he and Mr. Thiel now had a setting in which to try out their ideas about diversity and meritocracy. 'In the start-up crucible, performing is all that matters,' Mr. Sacks wrote about that time. He wanted to give all job applicants tests of cognitive ability, according to his colleague Keith Rabois, and when the company searched for a new chief executive, one of the requirements was an I.Q. of 160 -- genius level.

The goal was 'pure meritocracy,' said Amy Klement, one of a small number of women to rise high within the organization. She and other women called Mr. Sacks an effective, relentless, generous boss. But some also wondered how comfortable the men running the company were around them. Lauri Schultheis said that when she interviewed to be PayPal's office manager, and its first female employee -- before even Mr. Sacks arrived -- an engineer asked her, 'Does this mean I have to stop looking at porn? ...

Gender differences in preferences, choices, and outcomes: SMPY longitudinal study

The recent SMPY paper below describes a group of mathematically gifted (top 1% ability) individuals who have been followed for 40 years. This is precisely the pool from which one would hope to draw STEM and technological leadership talent. There are 1037 men and 613 women in the study.

The figures show significant gender differences in life and career preferences, which affect choices and outcomes even after ability is controlled for. (Click for larger versions.) According to the results, SMPY men are more concerned with money, prestige, success, creating or inventing something with impact, etc. SMPY women prefer time and work flexibility, want to give back to the community, and are less comfortable advocating unpopular ideas. Some of these asymmetries are at the 0.5 SD level or greater. Here are three survey items with a ~ 0.4 SD or more asymmetry:

# Society should invest in my ideas because they are more important than those of other people.

# Discomforting others does not deter me from stating the facts.

# Receiving criticism from others does not inhibit me from expressing my thoughts.

I would guess that Silicon Valley entrepreneurs and leading technologists are typically about +2 SD on each of these items! One can directly estimate M/F ratios from these parameters ...

Life Paths and Accomplishments of Mathematically Precocious Males and Females Four Decades Later  (Journal: Psychological Science)

David Lubinski, Camilla P. Benbow, and Harrison J. Kell
Vanderbilt University

Two cohorts of intellectually talented 13-year-olds were identified in the 1970s (1972–1974 and 1976–1978) as being in the top 1% of mathematical reasoning ability (1,037 males, 613 females). About four decades later, data on their careers, accomplishments, psychological well-being, families, and life preferences and priorities were collected. Their accomplishments far exceeded base-rate expectations: Across the two cohorts, 4.1% had earned tenure at a major research university, 2.3% were top executives at “name brand” or Fortune 500 companies, and 2.4% were attorneys at major firms or organizations; participants had published 85 books and 7,572 refereed articles, secured 681 patents, and amassed $358 million in grants. For both males and females, mathematical precocity early in life predicts later creative contributions and leadership in critical occupational roles. On average, males had incomes much greater than their spouses’, whereas females had incomes slightly lower than their spouses’. Salient sex differences that paralleled the differential career outcomes of the male and female participants were found in lifestyle preferences and priorities and in time allocation.

See also these poll results from the Harvard Crimson.

Crimson: ... The gender gap was also apparent in career choice. Men were far more likely to hope to eventually work in finance and entrepreneurship than women, while women were much more likely to aspire to careers in nonprofits and public service, health, and media or publishing. [ Note: these are super high achieving HARVARD kids in the survey, not state-U types ... no one has more "privilege" than they do, so I think it's fair to conclude that they might be expressing their relatively unconstrained actual preferences here. ]

Inside HBS: "kill, f^^k or marry"

I recommend this long NYTimes article about recent efforts at Harvard Business School to increase gender equity. If nothing else, it provides some insight into HBS and "elite business" culture. The contrast with East Asian business culture couldn't be more stark -- the emphasis at HBS is on getting your (possibly superficial or wrong) opinion out there as assertively as possible. Talking assertively is, by itself, considered a good thing regardless of content. This is a problem for many women, but it's also a problem for good decision making at firms ...

NYTimes: ... Some students, like Sheryl Sandberg, class of ’95, the Facebook executive and author of “Lean In,” sailed through. Yet many Wall Street-hardened women confided that Harvard was worse than any trading floor, with first-year students divided into sections that took all their classes together and often developed the overheated dynamics of reality shows. Some male students, many with finance backgrounds, commandeered classroom discussions and hazed female students and younger faculty members, and openly ruminated on whom they would “kill, sleep with or marry” (in cruder terms). Alcohol-soaked social events could be worse.

... By graduation, the school had become a markedly better place for female students, according to interviews with more than 70 professors, administrators and students, who cited more women participating in class, record numbers of women winning academic awards and a much-improved environment, down to the male students drifting through the cafeteria wearing T-shirts celebrating the 50th anniversary of the admission of women. Women at the school finally felt like, “ ‘Hey, people like me are an equal part of this institution,’ ” said Rosabeth Moss Kanter, a longtime professor.

And yet even the deans pointed out that the experiment had brought unintended consequences and brand new issues. The grade gap had vaporized so fast that no one could quite say how it had happened. The interventions had prompted some students to revolt, wearing “Unapologetic” T-shirts to lacerate Ms. Frei for what they called intrusive social engineering. Twenty-seven-year-olds felt like they were “back in kindergarten or first grade,” said Sri Batchu, one of the graduating men.

Students were demanding more women on the faculty, a request the deans were struggling to fulfill. And they did not know what to do about developments like female students dressing as Playboy bunnies for parties and taking up the same sexual rating games as men. “At each turn, questions come up that we’ve never thought about before,” Nitin Nohria, the new dean, said in an interview.

The administrators had no sense of whether their lessons would last once their charges left campus. As faculty members pointed out, the more exquisitely gender-sensitive the school environment became, the less resemblance it bore to the real business world. “Are we trying to change the world 900 students at a time, or are we preparing students for the world in which they are about to go?” a female professor asked.

... The men at the top of the heap worked in finance, drove luxury cars and advertised lavish weekend getaways on Instagram, many students observed in interviews. Some belonged to the so-called Section X, an on-again-off-again secret society of ultrawealthy, mostly male, mostly international students known for decadent parties and travel.

Women were more likely to be sized up on how they looked, Ms. Navab and others found. Many of them dressed as if Marc Jacobs were staging a photo shoot in a Technology and Operations Management class. Judging from comments from male friends about other women (“She’s kind of hot, but she’s so assertive”), Ms. Navab feared that seeming too ambitious could hurt what she half-jokingly called her “social cap,” referring to capitalization. ...

The goal of equalizing female representation at hedge and venture funds, and in aggressive areas of finance or entrepreneurship, will be challenging. A recent Crimson poll of the Harvard freshman class revealed:

Crimson: ... The gender gap was also apparent in career choice. Men were far more likely to hope to eventually work in finance and entrepreneurship than women, while women were much more likely to aspire to careers in nonprofits and public service, health, and media or publishing. [ Note: these are super high achieving HARVARD kids in the survey, not state-U types ... no one has more "privilege" than they do, so I think it's fair to conclude that they might be expressing their relatively unconstrained actual preferences here. ]

See also Having it All , Creators and Rulers , Credentialism and Elite Performance.

Creators and Rulers: ... I went to Harvard Business School, a self-styled pantheon for the business elite.

The average person was:
- top decile intellect (though probably not higher)
- top decile emotional intelligence (broadly construed - socially aware, self-aware, persuasion skills, etc.)
- highly conscientious / motivated

Few were truly brilliant intellectually. Few were academically distinguished (plenty of good ivy league degrees, but very few brilliant mathematical minds, etc.).

A good number will be at Davos in 20 years time.

Performance beyond a certain level in the vast majority of fields (and business is certainly one of them) is principally a function of having no cognitive and personal qualities which fall below a (high, but not insanely high) hygene threshold -- and then multiplied by determination, of course.

Conscientiousness, in fact, is the best single stable predictor of job success for complex jobs (well established in personality psychometrics).

Very high intelligence actually negatively correlates with career success (Kotter), probably because smart people enjoy solving problems, rather than making money selling things -- which outside of quant trading, show business and sport is really the only way of being really successful.

There are some extremely intelligent people in business (by which I mean high IQ, not just wise or experienced), but you tend to find them in the corners of the business landscape with the richest intellectual pastures: some areas of law, venture capital, some cutting edge technology fields.

Steve Ballmer - for instance - might deafen you, but he would not dazzle you.

PS I don't know much about Ballmer, but others claim that he is actually exceptionally intelligent, as are the other MSFT billionaires Gates, Allen, Simonyi. None of these individuals has an MBA ;-)

Having it All: opt outs want back in

No, you can't actually have it all -- neither as a man nor as a woman. If you want to spend time with your kids (I highly recommend it), that will take time away from your startup, hedge fund, climb up the ladder, investigations into quantum decoherence. You just have to strike a balance that you can deal with.

Men are on average more driven by career success and money than women, and similarly women are more, well, maternal than men. It's best to think about this (as with all questions dealing with groups of people) in terms of distributions rather than strict categories. There are outlier women who are better corporate warriors than 95% of men (but perhaps they comprise less than 5% of the female population!), and there are outlier men who are great stay at home dads. At least at the moment, and perhaps for deep evolutionary reasons, the male and female distributions are shifted relative to each other along these dimensions. To me, feminism means fighting for the rights of outliers to do what they want, while still respecting the larger number of women who might be happier in more traditional roles. In my opinion, noticing properties of distributions is not in any way anti-feminist.

NYTimes: ... The culture of motherhood, post-recession, had altered considerably, too. The women of the opt-out revolution left the work force at a time when the prevailing ideas about motherhood idealized full-time, round-the-clock, child-centered devotion. In 2000, for example, with the economy strong and books like “Surrendering to Motherhood,” a memoir about the “liberation” of giving up work to stay home, setting the tone for the aspirational mothering style of the day, almost 40 percent of respondents to the General Social Survey told researchers they believed a mother’s working was harmful to her children (an increase of eight percentage points since 1994). But by 2010, with recovery from the “mancession” slow and a record 40 percent of mothers functioning as family breadwinners, fully 75 percent of Americans agreed with the statement that “a working mother can establish just as warm and secure a relationship with her children as a mother who does not work.” And after decades of well-publicized academic inquiry into the effects of maternal separation and the dangers of day care, a new generation of social scientists was publishing research on the negative effects of excessive mothering: more depression and worse general health among mothers, according to the American Psychological Association.

I wondered if these changes affected the women who opted out years ago. Had they found the “escape hatch” from the rat race that one of Belkin’s interviewees said she was after? Were they able, as a vast majority said they had planned, to transition back into the work force? Or had they, as the author Leslie Bennetts predicted in her 2007 book, “The Feminine Mistake,” come to see that, by making themselves financially dependent upon their men — particularly at a time when no man could depend upon his job — they had made a colossal error?

The 22 women I interviewed, for the most part, told me that the perils of leaving the work force were counterbalanced by the pleasures of being able to experience motherhood on their own terms. A certain number of these women — the superelite, you might say, the most well-off, with the highest-value name-brand educational credentials and powerful and well-connected social networks — found jobs easily after extended periods at home. These jobs generally paid less than their previous careers and were less prestigious. But the women found the work more interesting, socially conscious and family-friendly than their old high-powered positions.

Pamela Stone, a professor of sociology at Hunter College and the author of the 2007 book “Opting Out? Why Women Really Quit Careers and Head Home,” heard many similarly glowing stories. In the early 2000s, she spent considerable time interviewing 54 well-off married mothers drawn primarily from the alumnae networks of several highly selective colleges and universities “who had navigated elite environments with competitive entry requirements,” as she described them in her book. Now she’s updating her research and has reached about 60 percent of her interviewees, two-thirds of whom have returned to work — their decisions sometimes prompted by their husbands’ somewhat reduced earnings, post-recession. “What I heard repeatedly was ‘The job found me’ or ‘The job fell into my lap,’ ” she told me.

Among the women I spoke with, those who didn’t have the highest academic credentials or highest-powered social networks or who hadn’t been sufficiently “strategic” in their volunteering (fund-raising for a Manhattan private school could be a nice segue back into banking; running bake sales for the suburban swim team tended not to be a career-enhancer) or who had divorced, often struggled greatly.

Note, moms with elite pedigrees have a much easier time getting back into the workforce after opting out to raise young kids.

Hmm ... this might affect average hourly wages by gender ... but too complex to make its way into the social science discourse ...

At a time when having a “good” job means working 50-plus hours a week, in addition to weekends and tech-tethered evenings, it’s not surprising that, if both spouses work, it can often feel as if neither is ever truly home. And that desire to be emotionally present at home, Pamela Stone, the sociologist, told me, became more pressing over time for the women she interviewed, reshaping their ambitions when they decided to go back to work.

While two-thirds of the women she reinterviewed originally worked in male-dominated professions like banking or corporate law, now only a quarter are employed in traditionally masculine and hard-driving fields. The rest chose more female-dominated, and far less lucrative, “caring, nurturing occupations” like teaching or nonprofit work, Stone said. Only one of the women she interviewed had returned to her former employer (in a “vastly different capacity, much diminished,” she said); and all have scaled down their ambitions.

“The longer they’re home, the more they continue the trajectory toward something different,” Stone told me. “They have greater appreciation of some of the values of home and connectivity, which were somewhat alien to them in their high-flying professions.”

Male and female science professors equally gender biased

This study (PNAS) surveyed 127 professors of biology, chemistry and physics, asking them to evaluate resumes of potential lab managers. Half the pool received a particular resume with a male name and the other half with a female name -- the applications were otherwise identical. There was a significant preference for male applicants over female applicants, and, strikingly, this preference was independent of the gender of the evaluator (professor).

Click for larger figure.

I've always felt that gender plays a big role in academic careers. Men in my field are much more likely to bluff, win arguments by intimidation, oversell results, etc. Usually if a woman says she understands a result or calculation, she really does.

See also Women in the Classroom.

Baumeister on Gender Differences and Culture

Nice discussion on Econtalk. I suspect Baumeister has slightly stronger opinions than he expressed to Russ.

Roy Baumeister of Florida State University and the author of Is There Anything Good About Men talks with EconTalk host Russ Roberts about the differences between men and women in cultural and economic areas. Baumeister argues that men aren't superior to women nor are women superior to men. Rather there are some things men are better at while women excel at a different set of tasks and that these tradeoffs are a product of evolution and cultural pressure. He argues that evolutionary pressure has created different distributions of talent for men and women in a wide variety of areas. He argues that other differences in outcomes are not due to innate ability differences but rather come from different tastes or preferences.

The podcast got me through 30 pullups, 100 pushups, situps, kettlebells and cycling :-)

Price and self-deception

Is the letter below for real, or just a clever parody? ("Shoes!") This old joke says it all:

A man meets a woman in a bar and asks her if he will have sex with him for a million dollars. The woman thinks about it for a moment and says yes.

The man then asks the woman if she will have sex with him for $20. The woman becomes incensed and says, “What do you take me for, a whore?”

The man replies, “Ma’am we’ve already established what you are, now we’re just negotiating price.”

Related posts. Via Maoxian.

Why I Love My Sugar Daddy: ... The dating pool in my town wasn’t the most appealing, so I took my search online. I was bombarded with messages from guys who couldn’t spell, took shirtless pictures of themselves in mirrors, and were perfectly content to be living in their parents’ basements. I was a driven pre-law student with a 4.0 GPA and dreams of a pitbull-esque career in corporate law. These candidates weren’t cutting it. I wanted a man who was ambitious and successful, someone who knew what he wanted and exactly how to get it. I wanted an established man.

I entered my specifications into Google, and the first hit was a Sugar Daddy dating site. “No way,” I thought. “I’m not a golddigger, I just want a man who has his shit together.” But the tagline had already hooked me– “Meet Wealthy Men Seeking to Spoil Beautiful Women!” It felt like I had just been challenged… was I attractive and charming enough to pique the interest of a successful millionaire? My mind raced. Is this thinly-veiled prostitution? Were there really men out there who wanted to buy me shoes? I like shoes! Was this going to affect how I identified myself as an intelligent, independent woman? PRESENTS! I caved. I set up a profile, paid the membership fee, and waited to see what would happen.

The difference in quality (my idea of quality, at least) between the two dating pools was… slightly disappointing. I was expecting some kind of Mensa utopia, but apparently shitheads exist in all tax brackets. Once I became more realistic about my expectations, the outlook was less bleak. There were men who read! Books! These men had careers and dreams and ambitions! I was getting messages that were entirely free of grammatical errors!

I learned very quickly that there were many different types of SD relationships, ranging from blatant prostitution/escorting to regular relationships with the perk of total financial stability. After going on a few dates and being flat-out propositioned, I decided I wasn’t into the whole sex-for-cash-in-an-unmarked-envelope deal. I received offers to be a travel companion– jetsetting to Bali or Brazil whenever a SD’s schedule allowed it– but as a busy student, that option didn’t seem too viable. I decided that I wanted a more traditional relationship, which is slightly harder to find, but (IMO) is the most rewarding. I was looking for someone who, like myself, was busy building their career and simply didn’t have all the time in the world to commit to a normal relationship. Something easy, fun, and drama-free, with a guy who could help me better myself in all areas.

After a year and a half of casual relationships with great guys, I met my current Sugar Daddy, The Lawyer. My first date with The Lawyer was… probably one of the most surreal experiences of my lower-middle class, smalltown life. After exchanging a few e-mails, phone calls, and Skype sessions (who knew 45-year olds knew how to use Skype?), we agreed to meet. Normally, a quick date at Starbucks would suffice, but The Lawyer lived 1500 miles away. Since I didn’t have a law firm to run, we decided it would be easier if I travelled to meet him. ...

... I had never even flown business class before, so a private jet was… well, it was fucking awesome. ...

When I first got into the whole Sugar Daddy relationship world, I was worried I was going to lose myself. I didn’t want people to think I was some kind of brainless, golddigging bimbo. I was worried that other people’s opinions of my love life would somehow change who I was and what I believed in. Of course, that’s total bullshit. I’m the exact same person I was two years ago, except with more shoes and less debt. SD relationships work for me, and not just monetarily. They fit well into my busy life, and most of the men I’ve met are smart, kind, and incredibly charming. I’m in a great relationship, and I have no reason to be ashamed of it. I’m not a brazenly parasitic adult baby. I’m just an intelligent, driven, career-oriented woman with a boyfriend who likes to buy me presents.

Click through for marvelous comments.

Annals of socially constructed gender roles

A typical conversation between my five year old twins. Guess which is the boy and which is the girl!

I: Let's play with my dolls.

M: You never want to play anything fun!

I: Like what?

M: Like guns, robots or dinosaurs!

Yesterday M asked me why in all the stories the prince does the fighting and the princess always needs rescuing. Unsure, I consulted mommy, who has a PhD in comparative literature from Berkeley. The answer is, apparently, that in the old days princesses were weak and so the princes had to do the fighting. Nowadays (as you can see on TV in Afghanistan) princesses can take care of themselves. M was very confused by this and keeps asking me why the princesses used to be so weak: did an evil wizard do it?

Gender differences in "extreme" mathematical ability, part 2

We had Andrew Penner of UC Irvine here last week to discuss his paper Gender Differences in Extreme Mathematical Achievement: An International Perspective on Biological and Social Factors. PDF.

I posted back in 2007 on some earlier research of Penner's which showed an 8 percent larger variance in male math ability already at the beginning of kindergarten. (This is not so different from the adult difference in variance.)

For a relatively balanced overview of this topic see Women's underrepresentation in science: Sociocultural and biological considerations; Ceci, Stephen J.; Williams, Wendy M.; Barnett, Susan M. Psychological Bulletin. Vol 135(2), Mar 2009, 218-261. Abstract, PDF.


In the more recent paper Penner claims that national variation in gender gaps in mathematical ability implies that the effect is culturally moderated. While I don't doubt that culture affects development of mathematical ability, and perhaps in such a way as to favor males, I question whether his paper or other recent papers relying on international tests like TIMSS and PISA really have the statistical power to investigate this issue very well. It is already hard to capture national differences in average ability level from tests of only a few thousand students (ensuring that these students are representative of the whole population is difficult); gender gaps are even smaller effects and therefore more sensitive to statistical and systematic error. See here (figure 4) for a convincing demonstration that PISA data on country by country gender gaps is noise dominated: the gaps are not stable between the 2003 and 2006 results. Only by aggregating the data over many countries do we arrive at a stable gap. This makes me suspicious of TIMSS results because PISA has significantly larger statistics. A meta-analysis suggests that cultural effects, while perhaps non-zero, are relatively small.

Andrew and I had an interesting discussion about his paper; my side is summarized in the message and two figures below.

Andrew,

Sorry I had to leave early from your talk and didn't get to discuss this in person. As I mentioned yesterday and in my earlier email, country level gender gaps are not stable between PISA 2003 and 2006, whereas the meta-analysis gap, averaging over all countries, is stable. This to me is clearly a signal that the PISA country level data on gender gaps is dominated by statistical error, and makes me strongly suspect the same is true for TIMSS.

In your talk you said that a biological model would imply the same gender gap in every country, and that country by country variation would undermine the biological model. However, you neglected to mention that statistical error would lead to country by country variation (of measured gaps) even in the biological model.

In the 1995 TIMSS table below there are 8 "gold standard" countries that complied with the statistical procedures. The data from the remaining countries would be suspect, since, as I mentioned, getting a representative sample for a country of millions is not an easy task. In particular, the standard error for countries outside the first group of 8 is likely to be much larger than quoted. (See the column labeled "Difference" in the table. The number in parenthesis is the standard error for the gender gap.)

For the gold standard countries, it appears that all gender gaps are within roughly 1-2 standard deviations (using the standard error given) of the group average, with the exception of Hungary which is an outlier. This suggests that the variation within this group could be entirely statistical. That is, if one formulated a "null model" with constant gender gap across countries, and asked whether TIMSS disfavors that model, the answer might be no, at least not in a statistically significant way. (Actually I suspect that the standard error given is an underestimate, because of systematic errors in the sampling procedures even in the gold standard countries.) Note within this set of countries there is a lot of variation on your societal indicators.

To summarize, I think the claim that TIMSS data supports country level variation in gender gaps has to be considered carefully for statistical significance. As I mentioned, I doubt one can really trust the TIMSS quoted standard errors, so a real test would be time stability of (measured) gender gaps -- a test which PISA fails.

One final comment on your talk: it seems to me that all of the societal variables you listed (labor force participation, wage gap, etc.) have changed significantly in the last 40 years in the US. Nevertheless, I believe gender gaps on the SAT-M (a truly large statistics measurement) have not narrowed during that time. (See second figure below.)

Steve

(Click for larger versions.)

The joy of gender imbalances on campus

The Chronicle of Higher Education reports on the social effects of gender imbalances. As we know, teenage girls are more likely than boys to have their acts together, hence make up a larger and larger percentage of those who attend college. I see this all the time in my intro classes -- a majority of the most organized students are female, and a majority of the least organized are male. Many universities will have to use affirmative action for male applicants in order to preserve 50-50 gender ratios.

Math puzzle: (optional for readers who have trouble with distributions) If most of the least able students are male, and yet men and women perform equally on average (actually this may not be true anymore, but see PISA data :-), what does that imply about the most able students on campus?

Chronicle: American colleges are undergoing a striking gender shift. In 2015 the average college graduating class will be 60-percent female, according to the U.S. Education Department. Some colleges have already reached or passed that threshold, which allows anecdotal insights into how those imbalances affect the pickup culture. What can be seen so far is not encouraging: Stark gender imbalances appear to act as an accelerant on the hookup culture.

...In 2006 I visited James Madison University, a public university with 17,000 students. At the time, women made up 61 percent of the campus population.

...A senior added: "The guys see that there are a lot more girls, and they're not interested in having a relationship longer than the next girl to come along. Men know how to take advantage of that competition. They'll set things up at parties to get girls to do stuff, such as having a slip and slide contest," in which girls strip to their underwear and get wet sliding through water on a plastic sheet.

As a result of the rising gender imbalances, the university has become "female centric." But while women may run the clubs, dominate in classes, and generally define the character of the university, the law of supply and demand rules the social scene. That's why the women are both competitive in seeking men and submissive in lowering their standards.

Men at the university don't dispute what the women say. "Since there's such an overwhelming number of girls, they have such competition between each other to get a guy," a male junior admitted. "The guys here aren't stupid. They're plenty aware of that and know that girls have to get into a fight over them, instead of what's normal with guys courting girls."

I wonder what a FaceBook search on the keywords "slip and slide" brings up?

Women in the classroom

Interesting comments from Judith Warner of the Times, as she reports on a brain science workshop for journalists, held at MIT. The audience was more engaged (less intimidated?) by female lecturers. I find as well that women are less likely to try to get by with "proof by intimidation" than men, and that their presence tends to improve the quality of scientific discussion, assuming an equal level of competence.

Anyone familiar with Feynman idolatry knows that "man crushes" are just as real as what is described below for women.

At M.I.T., we were mostly spoken to by men, various kinds of men, of different ages and with different speaking styles, and we interacted with them with typical reportorial formality. Some were more popular with us than others; some were more engaged with us than others. Some spoke right over our heads; some reached even me with perfect clarity.

Something very different happened, however, on the two occasions when we were spoken to by women. The atmosphere in the room changed. We all became more familiar. We asked more questions. We interrupted more. We made sounds of assent or dissent; we questioned methods, concepts, base assumptions. It was as though, with the women, the boundaries dissolved. We were all immediately drawn into relationships.

How much of this had to do with the fact that the women tended to speak more relationally (“I think,” “I feel”), I don’t know. I don’t know if it was created by the fact that the women — to varying degrees — turned the story of their work into personal narratives.

I know that there was no conscious desire on anyone’s part to talk back to them or treat them with less respect. But one woman in particular, Rebecca Saxe, a young, dynamic professor of neurobiology at M.I.T. who gave a riveting presentation on social cognition — “how we reason about the desires and intentions that motivate others’ actions” — was interrupted so much by her super-engaged audience that she didn’t have time to get through essential portions of her talk.

I did not ask questions of this amazing young woman. I was struck, once again, with one of my crippling bouts of shyness, and besides that, I was too busy writing down her every word and wondering why on earth I had never taken science and whether my daughters might attend M.I.T.

Maybe I could send them to do summer study, I thought. (Once they’d both learned their multiplication tables, of course.) Maybe I should sport little wire glasses and wear my hair in a long braid. Or buy Birkenstocks.

“What did you think?” I breathed to a fellow female fellow, as we filed out of the classroom for lunch.

“I have a crush on her,” she said. The women around us made approving noises.

“It was her passion and energy and approach that was infectious,” she later explained in an e-mail. “I really had an emotional reaction to her, and found myself day dreaming about being her friend.”

What is this thing we so often do, when confronted with an impressive woman? Why do they, in particular, set off such a Pavlovian rush of emotion? Why, for women in particular, do they set off this me/not me engagement, this game of my friend/not my friend, this eternal, sometimes infernal play of positive or negative mirroring?

Men do a version of this with women, too — though I think it plays out more in terms of validates me/doesn’t validate me, which may amount, in slightly altered form, to much the same thing. I don’t see them doing it with other men. I don’t hear of men getting “crushes” on other men because they’re impressed with them. They don’t seem to get so flooded with the desire to be them, to try on their skins; they don’t appear to be constantly testing their identities against another man’s example, calling into question, at the drop of a hat, their clothing style or hair or general sense of being in the world.

Gender differences in "extreme" mathematical ability

Since the Larry Summers debacle I've kept my eye out for relevant data on gender differences in mathematical ability. Finally I've found some analysis of results from a nationally representative study of elementary school children (K-5). Interestingly, the larger variance in male math performance is already observed at the beginning of kindergarten -- yes, before formal schooling has begun. By 3rd grade males are outperforming throughout the distribution, but the advantage at the high end is roughly unchanged. Note the authors consider 95 percentile to be "extreme" ability, which is kind of funny. You have to go quite a bit further out on the tail to find the talent pool from which professors of math, computer science, physical science and engineering are drawn.

Taking a quick look at their numbers, it appears that at the beginning of kindergarten the male distribution has standard deviation about 8 percent greater than the female distribution (larger variance -- both tails are overpopulated by males), although means and medians are pretty much the same. This implies that, already at age 5, at the 1 in 1000 talent level there will be roughly 2.5 times as many boys as girls. This ratio becomes larger and larger as one looks at more elite groups -- for 1 in 10k talents the ratio is something like 4 to 1 male to female. (I am extrapolating the normal distribution here, which might be a source of error.)

If subsequent societal effects were exactly gender neutral after age 5, one still might expect to find a strong asymmetry in gender representation in certain fields. Therefore, gender asymmetry in outcomes is not by itself evidence of discrimination at higher levels of the selection process. Removing gender bias at all levels, starting from kindergarten and continuing through grade school, high school, undergraduate, graduate and postdoctoral training, and, finally, faculty hiring, will not correct for the effect which is already present at age 5!

Note, I'm not claiming that the male advantage at age 5 is necessarily biological in origin -- it might be due to environmental causes. If one believes the causes are entirely environmental, and if one wants to equalize the numbers of male and female math geniuses, then intervention had better begin quite early -- extending to how mommies and daddies raise their infants.

In some other research by the same authors (I don't have a web link), international scores on the TIMSS examinations show that at the 90th percentile in math ability among seniors in high school, the ratio of males to females varies between roughly 2-3. This is a much larger discrepancy than the kindergarten numbers (strongly apparent already at only the 90th percentile), although it would be hard to know whether it is due to biological causes such as hormones and differences in male/female development, or to societal causes. The fact that there is some variation between countries does suggest at least a significant societal component.

If you read this post carefully, you will see that I have done little more than interpret the results of the nationwide testing examined in the paper below. Nevertheless, I anticipate I might get into trouble for having the temerity to perform this simple analysis. Let me therefore state, for the record, that I do believe that societal effects tend to discourage women from achievement in math and science, and that we can do much better than we currently are in promoting female representation in math-heavy fields. However, I do not think that there is any data supporting a complete absence of gender differences in the distribution of cognitive ability.

Gender Differences in Kindergartners Mathematics Achievement! Evidence from a Nationally Representative Sample

Paper presented at the annual meeting of the American Sociological Association (to appear in Social Science Research)

Paret, M. and Penner, A., Dept. of Sociology, UC Berkeley (2006, Aug)

Abstract: Gender differences in mathematics achievement are typically thought to emerge at the end of middle school and beginning of high school, yet some studies have found differences among younger children. Until recently the data available to examine gender differences among young children consisted of small non-nationally representative samples. This study utilizes data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 to analyze differences in a nationally representative sample of kindergarteners as they progress from kindergarten to third grade. Using quantile regression techniques to examine gender differences across the distribution, differences are found among students as early as kindergarten. Initially boys are found to do better at the top of the distribution and worse at the bottom, but by third grade boys do as well or better throughout the distribution.

The truth about men

Via NYTimes' Tierny Lab blog, this address to the American Psychological Association.

What was the audience reaction? Did people run from the room to avoid vomiting at Baumeister's horrible remarks? Do psychologists not have an intuitive understanding of variance? Why does Baumeister take so long to explain something so mathematically simple?

Former Harvard president Larry Summers' vile comments here.

Is There Anything Good About Men?

R. Baumeister, Eppes Eminent Professor of Psychology & Head of Social Psychology Area, Florida State University

... I’m sure you’re expecting me to talk about Larry Summers at some point, so let’s get it over with! You recall, he was the president of Harvard. As summarized in The Economist, “Mr Summers infuriated the feminist establishment by wondering out loud whether the prejudice alone could explain the shortage of women at the top of science.” After initially saying, it’s possible that maybe there aren’t as many women physics professors at Harvard because there aren’t as many women as men with that high innate ability, just one possible explanation among others, he had to apologize, retract, promise huge sums of money, and not long afterward he resigned.

What was his crime? Nobody accused him of actually discriminating against women. His misdeed was to think thoughts that are not allowed to be thought, namely that there might be more men with high ability. The only permissible explanation for the lack of top women scientists is patriarchy — that men are conspiring to keep women down. It can’t be ability. Actually, there is some evidence that men on average are a little better at math, but let’s assume Summers was talking about general intelligence. People can point to plenty of data that the average IQ of adult men is about the same as the average for women. So to suggest that men are smarter than women is wrong. No wonder some women were offended.

But that’s not what he said. He said there were more men at the top levels of ability. That could still be true despite the average being the same — if there are also more men at the bottom of the distribution, more really stupid men than women. During the controversy about his remarks, I didn’t see anybody raise this question, but the data are there, indeed abundant, and they are indisputable. There are more males than females with really low IQs. Indeed, the pattern with mental retardation is the same as with genius, namely that as you go from mild to medium to extreme, the preponderance of males gets bigger.

All those retarded boys are not the handiwork of patriarchy. Men are not conspiring together to make each other’s sons mentally retarded.

Almost certainly, it is something biological and genetic. And my guess is that the greater proportion of men at both extremes of the IQ distribution is part of the same pattern. Nature rolls the dice with men more than women. Men go to extremes more than women. It’s true not just with IQ but also with other things, even height: The male distribution of height is flatter, with more really tall and really short men. Again, there is a reason for this, to which I shall return.

Tierney's summary:

“I’m certainly not denying that culture has exploited women,” he said. “But rather than seeing culture as patriarchy, which is to say a conspiracy by men to exploit women, I think it’s more accurate to understand culture (e.g., a country, a religion) as an abstract system that competes against rival systems — and that uses both men and women, often in different ways, to advance its cause.”

The “single most underappreciated fact about gender,” he said, is the ratio of our male to female ancestors. While it’s true that about half of all the people who ever lived were men, the typical male was much more likely than the typical woman to die without reproducing. Citing recent DNA research, Dr. Baumeister explained that today’s human population is descended from twice as many women as men. Maybe 80 percent of women reproduced, whereas only 40 percent of men did.

“It would be shocking if these vastly different reproductive odds for men and women failed to produce some personality differences,” he said, and continued:

For women throughout history (and prehistory), the odds of reproducing have been pretty good. Later in this talk we will ponder things like, why was it so rare for a hundred women to get together and build a ship and sail off to explore unknown regions, whereas men have fairly regularly done such things? But taking chances like that would be stupid, from the perspective of a biological organism seeking to reproduce. They might drown or be killed by savages or catch a disease. For women, the optimal thing to do is go along with the crowd, be nice, play it safe. The odds are good that men will come along and offer sex and you’ll be able to have babies. All that matters is choosing the best offer. We’re descended from women who played it safe.

For men, the outlook was radically different. If you go along with the crowd and play it safe, the odds are you won’t have children. Most men who ever lived did not have descendants who are alive today. Their lines were dead ends. Hence it was necessary to take chances, try new things, be creative, explore other possibilities.

The second big motivational difference between the genders, he went on, involves the kind of social relationships sought by each sex. While other researcher have argued that women are more “social” than men – more helpful and less aggressive towards others — Dr. Baumeister argued that women can be plenty aggressive in the relationships that matter most to them, which are intimate relationships. Men are more aggressive when it comes to dealing with strangers, because they’re more interested than women are in a wider network of shallow relationships.

“We shouldn’t automatically see men as second-class human beings simply because they specialize in the less important, less satisfying kind of relationship,” he said. Men are social, too, he said, just in a different way, with more focus on larger groups: “If you make a list of activities that are done in large groups, you are likely to have a list of things that men do and enjoy more than women: team sports, politics, large corporations, economic networks, and so forth.”

Male, female and Einstein's brains

This portrait of neuroscientist Sandra Witelson reveals some interesting details about gender differences in brain structure, and of Einstein's brain. Apparently Einstein's brain had no fissure separating the two parietal lobes.

"What is astonishing to me," Witelson said, "is that it is so obvious that there are sex differences in the brain and these are likely to be translated into some cognitive differences, because the brain helps us think and feel and move and act.

"Yet there is a large segment of the population that wants to pretend this is not true."

No one knows how these neural differences between the sexes translate into thought and behavior — whether they might influence the way men and women perceive reality, process information, form judgments and behave socially.

...As Witelson's research helped establish, however, the mental divide between the sexes is more complex and more rooted in the fundamental biology of the brain than many scientists once suspected.

In the last decade, studies of perception, cognition, memory and neural function have found apparent gender differences that often buck conventional prejudices.

Women's brains, for instance, seem to be faster and more efficient than men's.

All in all, men appear to have more gray matter, made up of active neurons, and women more of the white matter responsible for communication between different areas of the brain.

Overall, women's brains seem to be more complexly corrugated, suggesting that more complicated neural structures lie within, researchers at UCLA found in August.

Men and women appear to use different parts of the brain to encode memories, sense emotions, recognize faces, solve certain problems and make decisions. Indeed, when men and women of similar intelligence and aptitude perform equally well, their brains appear to go about it differently, as if nature had separate blueprints, researchers at UC Irvine reported this year.

"If you find that men and women have fundamentally different brain architectures while still accomplishing the same things," said neuroscientist Richard Haier, who conducted the study, "this challenges the assumption that all human brains are fundamentally the same."

[Einstein's brain:]

Witelson and her colleagues carefully compared the 40-year-old tissue samples with dozens of normal male and female brains in her collection. She also compared them with brains from eight elderly men to account for any changes due to Einstein's age at the time of his death.

She found that one portion of Einstein's brain perhaps related to mathematical reasoning — the inferior parietal region — was 15% wider than normal.

Witelson also found that it lacked a fissure that normally runs along the length of the brain. The average human brain has two distinct parietal lobe compartments; Einstein's had one.

Perhaps the synapses in this area were more densely interconnected.

"Maybe this was one of the underlying factors in his brilliance," she said. "Maybe that is how it works."