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Gender in science

Discussion about the distribution and relative career success of women in science has a long history and seem unlikely to reach a conclusions any time soon. PLoS Biology made a contribution with a piece from Peter Lawrence back in January. The latest ripple effect from that has just appeared as “An open letter to Nature“.

Peter Lawrence’s piece was called “Men, Women, and Ghosts in Science“. I hope it’s not oversimplifying too much to say that he argued that the way science is practiced puts undue premium on aggressiveness and that “Science would be better served if we gave more opportunity and power to the gentle, the reflective, and the creative individuals of both sexes.“.

The e-Letter responses to this article on our website were on the whole very supportive of Lawrence’s article; some even commended PLoS Biology for “having the courage to publish it“.

In July his year however Nature published a Commentary piece from Ben Barres called “Does gender matter?” which gave The Lawrence piece quite a mauling. I had difficulty recognising the Lawrence article in the description that Barres gave of it and would argue that he was unfairly misrepresented.

Barres’s piece sparked some critical debate in the pages of Nature and also a lot of support on the Nature Newsblog. By far the most detailed response however was posted by ‘agnostic’ on the Gene Expression blog. This in turn has resulted in an open letter to Nature, criticising the Barres piece in very strong terms, again on the Gene Expression blog.

This debate is becoming both heated and aggressive, two things that are guaranteed to prevent any constructive consensus being reached.

  1. When an advantaged group of people calls a disadvantaged group innately less able, you must forgive the disadvantaged folks if they try to defend themselves.

    First, the debate here is about the facts — and the facts are not determined by who is advocating them, but by reality.

    Second, in academia the disadvantaged are those who have the courage to speak out against biology denial. Very few people in academia have the courage to speak out when senior faculty monolithically condemn the positions of Summers, Pinker, and even Lawrence. Even those with tenure figure it’s just not worth it to be attacked — as they were in your article, which denounced the very idea of free speech as “verbal violence”.

    Fortunately we have the internet, the last refuge of anonymous free speech — and we can use it to point out some important papers on sex differences on the brain. Here’s just a sample of a voluminous literature:

    Sexually dimorphic gene expression in mouse brain precedes gonadal differentiation.

    * Dewing P,
    * Shi T,
    * Horvath S,
    * Vilain E.

    Department of Human Genetics, University of California, Los Angeles, CA 90095, USA.

    The classic view of brain sexual differentiation and behavior is that gonadal steroid hormones act directly to promote sex differences in neural and behavioral development. In particular, the actions of testosterone and its metabolites induce a masculine pattern of brain development, while inhibiting feminine neural and behavioral patterns of differentiation. However, recent evidence indicates that gonadal hormones may not solely be responsible for sex differences in brain development and behavior between males and females. Here we examine an alternative hypothesis that genes, by directly inducing sexually dimorphic patterns of neural development, can influence the sexual differences between male and female brains. Using microarrays and RT-PCR, we have detected over 50 candidate genes for differential sex expression, and confirmed at least seven murine genes which show differential expression between the developing brains of male and female mice at stage 10.5 days post coitum (dpc), before any gonadal hormone influence. The identification of genes differentially expressed between male and female brains prior to gonadal formation suggests that genetic factors may have roles in influencing brain sexual differentiation.

    Positron Emission Tomography with [18F]deoxyglucose was used to compare brain activation in men and women while they performed mathematical reasoning.
    Right greater than left-hemisphere activation was predicted, especially in temporal lobes. Forty-four participants were selected and matched for high or average Scholastic Aptitude Test-Math scores. There were no sex differences in cortical glucose metabolic rate (GMR). However, GMR in temporal lobe regions was positively correlated with math reasoning score in men but not in women. The temporal lobes, bilaterally, are implicated in math reasoning ability for men; no specific cortical areas were related to math reasoning performance in women.

    Gender and parental status affect the visual cortical response to infant facial expression.

    * Proverbio AM,
    * Valentina B,
    * Matarazzo S,
    * Del Zotto M,
    * Zani A.

    Department of Psychology, University of Milano-Bicocca, Viale dell’Innovazione 10, 20126 Milan, Italy; Institute of Molecular Bioimaging and Physiology, National Research Council (CNR), Segrate-Milan, Italy.

    This study sought to determine the influence of gender and parental status on the brain potentials elicited by viewing infant facial expressions. We used ERP recording during a judgement task of infant happy/distressed expression to investigate if viewer gender or parental status affects the visual cortical response at various stages of perceptual processing. ERPs were recorded in 38 adults (male/female, parents/non-parents) during processing of infant facial expressions that varied in valence and intensity. All infants were unfamiliar to viewers. The lateral occipital P110 response was much larger in women than in men, regardless of facial expression, thus indicating a gender difference in early visual processing. The occipitotemporal N160 response provided the first evidence of discrimination of expressions of discomfort and distress and demonstrated a significant gender difference within the parent group, thus suggesting a strong interactive influence of genetic predisposition and parental status on the responsivity of visual brain areas. The N245 component exhibited complete coding of the intensity of facial expression, including positive expressions. At this processing stage the cerebral responses of female and male non-parents were significantly smaller than those of parents and insensitive to differences in the intensity of infant suffering. Smaller P300 amplitudes were elicited in mothers versus fathers, especially with infant expressions of suffering. No major group differences were observed in cerebral responses to happy or comfortable expressions. These findings suggest that mere familiarity with infant faces does not explain group differences.

    Gender differences in the neural correlates of response inhibition during a stop signal task.

    * Li CS,
    * Huang C,
    * Constable RT,
    * Sinha R.

    Department of Psychiatry, Yale University, New Haven, CT 06519, USA.

    We used functional magnetic resonance imaging to examine gender differences in the neural correlates of response inhibition during a stop signal task. The task has a frequent “go” signal to set up a pre-potent response tendency and a less frequent “stop” signal for subjects to withhold their response. A contrast in brain activation was made between successful and failed inhibitions for individual subjects. We compared 20 men and 20 women matched in age and years of education and in stop signal performance, with stop success rate, post-error slowing and task-related frustration ratings as covariates. The results showed greater activation in men, compared to women, in a wide array of cortical and subcortical areas, including the globus pallidus and motor thalamus during stop signal inhibition. In contrast, no brain regions demonstrated greater activation in women, even at a lower statistical threshold. Moreover, while men activated the medial superior frontal and anterior cingulate cortices, women activated the caudate tail to mediate response inhibition. These results extended gender differences in regional brain activation to response inhibition during a cognitive motor task. Men activated the motor circuitry while women appeared to involve visual association or habit learning during stop signal performance.

    Gender differences in neurological disease: role of estrogens and cytokines.

    * Czlonkowska A,
    * Ciesielska A,
    * Gromadzka G,
    * Kurkowska-Jastrzebska I.

    Institute of Psychiatry and Neurology, Second Department of Neurology, Warsaw, Poland.

    Increasing evidence suggests that inflammatory response may be a critical component of different brain pathologies. However, the role played by this reaction is not fully understood. The present findings suggest that neuroinflammtory mediators such as cytokines may be involved in a number of key steps in the pathological cascade of events leading to neuronal injury. This hypothesis is strongly supported by experimental and clinical observations indicating that inhibition of the inflammatory reaction correlates with less neuronal damage. Estrogens are thought to play a role in the sex difference observed in many neurological diseases with inflammatory components including stroke, Alzheimer’s and Parkinson’s diseases, multiple sclerosis, or amyotrophic lateral sclerosis. Clinical and experimental studies have established estrogen as a neuroprotective hormone in these diseases. However, the exact mechanisms involved in the neuroprotective effects of estrogens are still unclear. It is possible that the beneficial effects of these hormones may be dependent on their inhibitory activity on the inflammatory reaction associated with the above-mentioned brain pathologies. Here, we review the current clinical and experimental evidence with respect to the inflammation-modulating effects of estrogens as one potential explanatory factor for sexual dimorzphism in the prevalence of numerous neurological diseases.

    Blueprints for behavior: genetic specification of neural circuitry for innate behaviors.

    * Manoli DS,
    * Meissner GW,
    * Baker BS.

    Medical Scientist Training Program, Neurosciences Program and Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA.

    Innate behaviors offer a unique opportunity to use genetic analysis to dissect and characterize the neural substrates of complex behavioral programs. Courtship in Drosophila involves a complex series of stereotyped behaviors that include numerous exchanges of multimodal sensory information over time. As we will discuss in this review, recent work has demonstrated that male-specific expression of Fruitless transcription factors (Fru(M) proteins) is necessary and sufficient to confer the potential for male courtship behaviors. Fru(M) factors program neurons of the male central and peripheral nervous systems whose function is dedicated to sexual behaviors. This circuitry seems to integrate sensory information to define behavioral states and regulate conserved neural elements for sex-specific behavioral output. The principles that govern the circuitry specified by Fru(M) expression might also operate in subcortical networks that govern innate behaviors in mammals.

    So, to recap: we know that sex differences impact mammalian brains well before puberty. We know that in humans, they predict all kinds of neurological differences, from responses to the presence of a baby to differences in motor circuitry. We know that in other metazoans we have manipulated the genetic determinants of sexual behavior. And we know that sex differences predict differences in spatial reasoning, differences which manifest themselves in MRI scans, differences known to *impact mathematical ability*.

    It is this kind of evidence which was not addressed in your article in Nature.

  2. It is remarkable that any one could read my commentary “Does Gender Matter?” and conclude that I said that there are not innate differences between male and female brains. Nothing could be further from the truth. The point of my commentary was to say that there is no convincing evidence that these innate differences are relevant to women’s ability to advance in science. Rather the weight of the evidence is that prejudice and bias are responsible for the great majority, if not all, of the problem.

  3. Correction: Meant to say in my last sentence “prejudice and social factors (like lack of child care support for instance) are responsible…”

  4. Dr. Barres,

    Your Nature commentary is rather unrepresentative of the relevant literature. I suggest that you read the references cited in the letter written by Godless Capitalist and myself and the post by our colleague Agnostic.

    When the population is sampled from the right extreme of the distribution, sex differences are readily found. This point is even acknowledged by Leahy and Guo in their discussion. Take the Study of Mathematically Precocious Youth, in which the SAT was administered to all students in the participating junior high schools (a sample numbering in the hundreds of thousands).

    Top 1 in 1000: A 10-Year Follow-up of the Profoundly Gifted, J.Appl.Psycol. 86, 718-729 (2001).

    The above paper analyzed educational outcomes in scorers estimated by normal theory to be among the top 1 in 10,000 in IQ. It should be noted that there is absolutely no question that the SAT is a legitimate proxy for IQ and possesses high validity for the prediction of school achievement, choice of major, and even the probability of obtaining a patent. These generalizations are supported in this very study; this top 1-in-10,000 cohort pursued Ph.D. degress at over 50 times base expectations and boast a long list of accomplishments that includes scientific publications, software innovations, NSF fellowships, a “design for image correlation system for Mars landing program,” a physics teaching award, and also several non-scientific distinctions (e.g., a proposal for a voting system in the South African constitution). The items listed in the paper actually underestimate the accomplishments of this cohort (which on average must be under 25 years in age) because some chose not to volunteer biographical information for fear of being identified.

    What sex differences are evident when the cutting score is set this extraordinarily deep into the right tail of the ability distribution? A subgroup of these gifted individuals consisting of those with SAT profiles skewed toward math shows a male:female ratio of 169:16. A subgroup with a relatively balanced profile (i.e., more or less equal scores on the SAT-M and SAT-V) shows a male:female ratio of 53:9. A subgroup with a verbal skew shows a ratio of 31:42.

    Of the high-math group, what percent of the boys and girls respectively (who, recall, took the SAT as pre-adolescents) majored in math, physical science, engineering, and computer science? 72% and 44%. What about master’s degrees? 27% and 25%. That is four women earning master’s degrees. Obviously, sample size is inadequate to support rigorous inference. But the reason the sample is so small is that talent searches in junior high schools turn up so few girls scoring >700 on the SAT-M. What about Ph.D.’s? 24% and 12.5%.

    Among the balanced group, the breakdown for bachelor’s, master’s, and doctorates in math, physical science, engineering, is 60% v. 44%, 21% v. zero, and 30% v. zero.

    Among the high-verbal group, it’s 45% v. 17%, 16% v. 5%, and 10% v. 2%.

    These findings (which indicate sex differences in both mental abilities and non-cognitive factors) are quite representative of the literature. In constrast, your characterization of the average phenotypic differences at issue and their impact on real-world outcomes is far out of tune with the massive body of relevant evidence and the judgments of those authorities who are most familiar with it (Camilla Benbow, Diane Halpern, Linda Gottfredson, etc.).

    Given the plentiful psychological evidence of which this comment provides a miniscule sample (and the corresponding molecular evidence pointed to by Godless Capitalist), surely any reasonable person must agree that it is at the very least an open question as to whether biologically rooted parameters contribute to the observed sex disparities across scientific disciplines in addition to whatever sociocultural forces may be at play. And a more or less definite answer to this question should be pursued with all possible rigor, as such an answer may contribute to a resolution of an important social issue and to advance our self-understanding as a species. For this reason I strongly urge that you reconsider your dogmatic disparagement of hypotheses invoking biological factors, no matter how distasteful you find them. I believe that impartiality with respect to even the most painful and emotionally laden issues is the only stance reconciliable with a sound scientific conscience.

    Darth Quixote

  5. It is remarkable that any one could read my commentary “Does Gender Matter?” and conclude that I said that there are not innate differences between male and female brains. Nothing could be further from the truth.

    It is certainly not remarkable given the content of your article, which included many passages which referred to innate differences (and the proponents thereof) in disparaging terms, yet included no citations whatsoever to the voluminous literature on innate differences between male and female brains (Box 1 — the only place where even an indirect nod is made to this research — contains anecdotes, not citations). For example:

    Barres: Last year, Harvard University president Larry Summers suggested that differences in innate aptitude rather than discrimination were more likely to be to blame for the failure of women to advance in scientific careers…Lawrence draws from the work of Simon Baron-Cohen4 in arguing that males are ‘on average’ biologically predisposed to systematize, to analyse and to be more forgetful of others, whereas females are ‘on average’ innately designed to empathize, to communicate and to care for others….I am suspicious when those who are at an advantage proclaim that a disadvantaged group of people is innately less able….there is little evidence that gender differences in maths abilities exist, are innate or are even relevant …The comments of Summers, Mansfield, Pinker and Lawrence about women’s lesser innate abilities are all wrongful and personal attacks on my character and capabilities…Mansfield and others claim that women are more emotional than men. There is absolutely no science to support this contention…There is no scientific support, either, for the contention that women are innately less competitive…

    And on and on it goes. Almost every sentence in which the word “innate” appears is surrounded with dismissive, disdainful context. Both careful and casual readers alike could be forgiven for believing you to be rather hostile to the idea of innate differences between male and female brains.

    But for the sake of argument let us agree that you do (now) grant that there are significant innate differences — inborn differences — on average between the genders, not just in terms of hormonal levels and secondary sexual characteristics, not just in terms of hardwired sexual preferences and physical strength, but also in terms of neurological properties and behavioral traits.

    Your position, then, is that though such differences exist that they are *immaterial* to anything of importance regarding scientific or mathematical output. That is, brain differences between genders exist — they just can’t affect anything in the real world of importance, such as the likelihood of becoming a scientist (not to mention a construction worker or a nursery school teacher). It doesn’t matter whether women are shown to have better verbal abilities on average than men or whether men are shown to differ from women by a full SD in average 3D visualization ability…all of this is ostensibly immaterial to the question of what professions they might choose to pursue.

    This sort of airlock between theory and practice is reminiscent of the way fundamentalist Christians separate their use of antibiotics from their antipathy towards evolution. Somehow you wish to accept modern neuroscience — complete with manipulation of sexual behavior in fruit flies and brain imaging of gender differences in cognition — while walling it off from any real world relevance. As you say:

    there is no convincing evidence that these innate differences are relevant to women’s ability to advance in science.

    So let’s rebut this claim directly. For the sake of brevity, I will focus on one point.
    Again from the original article:

    Barres: there is no evidence that sexually dimorphic brain wiring is at all relevant to the abilities needed to be successful in a chosen academic career. I underwent intensive cognitive testing before and after starting testosterone treatment about 10 years ago. This showed that my spatial abilities have increased as a consequence of taking testosterone.

    So, spatial abilities increase as a consequence of taking testosterone — one of the biggest biochemical differences between males and females. Is it really plausible to state that spatial abilities are irrelevant to mathematical ability? Or that the ability to manipulate CAD/CAM drawings, to develop statistical visualization algorithms, and to calculate rotation matrices are irrelevant to scientific and engineering progress? The literature indicates otherwise:

    Importance of Assessing Spatial Ability in Intellectually Talented Young Adolescents: A 20-Year Longitudinal Study

    …It appears that spatial ability assessments can complement contemporary talent search procedures. The amount of lost potential for artistic, scientific, and technical disciplines that results from neglecting this critical dimension of nonverbal ideation is discussed….

    Proficiency in spatial ability has long been associated with success in cognitively demanding educational tracks and occupations such as engineering, architecture, physics, chemistry, and medical surgery…strong abilities in these areas are salient characteristics of physical scientists. Gardner (1993) agrees and suggests “it is skill in spatial ability which determines how far one will progress in the sciences” (p. 192). Others have made similar observations (Hedges & Nowell 1995; Humphreys, Lubinski, & Yao 1993)…Wide agreement exists that spatial ability distinguishes group membership and performance in cetain artistic, engineering, and scientific disciplines.

    Utility of predicting group membership and the role of spatial visualization in becoming an engineer, physical scientist, or artist.

    Humphreys LG, Lubinski D, Yao G.

    Department of Psychology, University of Illinois, Champaign 61820.

    This article has two themes: First, we explicate how the prediction of group membership can augment test validation designs restricted to prediction of individual differences in criterion performance. Second, we illustrate the utility of this methodology by documenting the importance of spatial visualization for becoming an engineer, physical scientist, or artist. This involved various longitudinal analyses on a sample of 400,000 high school students tracked after 11 years following their high school graduation. The predictive validities of Spatial-Math and Verbal-Math ability composites were established by successfully differentiating a variety of educational and occupational groups. One implication of our findings is that physical science and engineering disciplines appear to be losing many talented persons by restricting assessment to conventional mathematical and verbal abilities, such as those of the Scholastic Aptitude Test (SAT) and the Graduate Record Examination (GRE).

    Gender differences in advanced mathematical problem solving.

    * Gallagher AM,
    * De Lisi R,
    * Holst PC,
    * McGillicuddy-De Lisi AV,
    * Morely M,
    * Cahalan C.

    Educational Testing Service, Princeton, New Jersey 08541, USA.

    Strategy flexibility in mathematical problem solving was investigated. In Studies 1 and 2, high school juniors and seniors solved Scholastic Assessment Test-Mathematics (SAT-M) problems classified as conventional or unconventional. Algorithmic solution strategies were students’ default choice for both types of problems across conditions that manipulated item format and solution time. Use of intuitive strategies on unconventional problems was evident only for high-ability students. Male students were more likely than female students to successfully match strategies to problem characteristics. In Study 3, a revised taxonomy of problems based on cognitive solution demands was predictive of gender differences on Graduate Record Examination-Quantitative (GRE-Q) items. Men outperformed women overall, but the difference was greater on items requiring spatial skills, shortcuts, or multiple solution paths than on problems requiring verbal skills or mastery of classroom-based content. Results suggest that strategy flexibility is a source of gender differences in mathematical ability assessed by SAT-M and GRE-Q problem solving. Copyright 2000 Academic Press.

    Moreover, the male-female difference on this particular variable (spatial visualization) is one of the largest on any mental test known to date:

    Sex Differences in the Brain, Scientific American, May 13 2002

    In examining the nature of sex differences in navigating routes, one study found that men completed a computer simulation of a maze or labyrinth task more quickly and with fewer errors than women did. Another study by different researchers used a path on a tabletop map to measure route learning. Their results showed that although men learned the route in fewer trials and with fewer errors, women remembered more of the landmarks, such as pictures of different types of buildings, than men did. These results and others suggest that women tend to use landmarks as a strategy to orient themselves in everyday life more than men do.

    Other findings seemed also to point to female superiority in landmark memory. Researchers tested the ability of individuals to recall objects and their locations within a confined space–such as in a room or on a tabletop. In these studies, women were better able to remember whether items had changed places or not. Other investigators found that women were superior at a memory task in which they had to remember the locations of pictures on cards that were turned over in pairs. At this kind of object location, in contrast to other spatial tasks, women appear to have the advantage.

    It is important to keep in mind that some of the average sex differences in cognition vary from slight to quite large and that men and women overlap enormously on many cognitive tests that show average differences. For example, whereas women perform better than men in both verbal memory (recalling words from lists or paragraphs) and verbal fluency (finding words that begin with a specific letter), we find a large difference in memory ability but only a small disparity for the fluency tasks. On the whole, variation between men and women tends to be smaller than deviations within each sex, but very large differences between the groups do exist–in men’s high level of visual-spatial targeting ability, for one.

    Although it used to be thought that sex differences in problem solving did not appear until puberty, the accumulated evidence now suggests that some cognitive and skill differences are present much earlier. For example, researchers have found that three- and four-year-old boys were better at targeting and at mentally rotating figures within a clock face than girls of the same age were. Prepubescent girls, however, excelled at recalling lists of words.

    Sex differences in visuospatial ability: do performance factors play such an important role?

    * Delgado AR,
    * Prieto G.

    Universidad de Salamanca, Spain.

    This study was designed to analyze some performance factors as a possible source of sex-related bias in psychometric tests of visuospatial aptitude. Goldstein, Haldane, and Mitchell (1990) explored the effect of two response styles-slowness of performance and reluctance to guess-by using a 3-D mental rotation test (the task showing the largest cognitive sex difference) and found that time limits and raw scores contributed substantially to the male advantage. We applied two tests in the speed-power continuum to a representative sample of 621 males and 821 females in their last year of high school in a 2 x 2 (gender x time) full factorial design. Reluctance to guess was similar for males and females. Males obtained more correct responses on both tests, and for both time conditions, than did females. These results are not only statistically significant but also are of substantial practical consequence.

    And at least part of the molecular mechanism is known — namely testosterone:

    Sex hormones affect spatial abilities during the menstrual cycle.

    * Hausmann M,
    * Slabbekoorn D,
    * Van Goozen SH,
    * Cohen-Kettenis PT,
    * Gunturkun O.

    Biopsychologie, Fakultat fur Psychologie, Ruhr-Universitat Bochum, Germany.

    The aim of this study was (a) to show that different measures of spatial cognition are modulated by the menstrual cycle and (b) to analyze which steroid is responsible for these cognitive alterations. The authors collected blood samples in 3-day intervals over 6 weeks from 12 young women with a regular menstrual cycle to analyze concentrations of estradiol, progesterone, testosterone, luteinizing hormone, and follicle-stimulating hormone. The performance on 3 spatial tests was measured during the menstrual and the midluteal phases. A significant cycle difference in spatial ability as tested by the Mental Rotation Test was found, with high scores during the menstrual phase and low scores during the midluteal phase. Testosterone had a strong and positive influence on mental rotation performance, whereas estradiol had a negative one. These results clearly indicate that testosterone and estradiol are able to modulate spatial cognition during the menstrual cycle.


    The point of all these references, in sum, is this:

    1) spatial visualization ability is one of the largest average cognitive differences between men and women
    2) this cognitive difference is known to be at least partly based in biochemistry (namely testosterone)
    3) and reams of literature support the fact that such ability is a strong predictor of scientific ability in general.

    Hence this is but one of many known sex differences in the brain which are partially responsible for the observed pattern of sex differences in professional choices. I should probably reiterate at this point that stating that A and B have *different* inclinations and aptitudes is clearly *not* equivalent to stating that A is “inferior” to B.

    Note also that the references cited above are but a drop in the ocean of literature on this topic; I have specifically limited my remarks here to sex differences in spatial visualization and their consequences for professional choices, one of the most cut & dried issues in the sex difference literature — a cut & dried issue whose manifest relevance to scientific achievement you nevertheless deny.

  6. there are a few assumptions here i’d like to see backed up.

    1. Differences in SAT test scores are the result of innate differences. I think the fact that a 1 month test-taking course can bump a score by over 100 points scuttles that. As the ETS itself says “it is a myth that a test will provide a unitary, unequivocal yardstick for ranking on merit.” SAT scores also over predict future male performance and underpredict femal performance in university. Students perform lower if their expectations of their own ability are lowered or they are aware of race/gender differences in test outcomes (hmmm, how would that happen?).

    2. The sciences as a whole are made up of people that fall at the far-right edge of whatever cognitive ability curve you’re talking about. (And you have to do better than anecdotes from particular disciplines, like spatial grasp and certain engineering fields.)

    3. Academic science is purely meritocratic, and having a bit more of a particular science-related ability will help you have a more successful scientific career (as opposed to, say, the ability to manage a lab full of students and postdocs, grant writing skills, work ethic, ability to get your name on papers with minimal input/effort, writing a lot of reviews, being buddies with journal editors, being a convincing and charismatic advocate of your ideas at conferences, etc, etc…)

    4. Relatedly, the higher you go up in academic prestige (tenure, promotion) correlates with (let alone is caused by) innate abilites.

    Given that discrimination that actively excludes and underrates females (and no, I’m not saying the disparity itself is evidence of discrimination–a new favorite straw man) has been demonstrated far more convincingly than the argument that innate cognitive difference–innate or otherwise–determine academic career success, why do you find it so easy to dismiss discrimination as a primary cause? Doesn’t it just make sense to work harder toward meritocracy and then see where we stand?

    When scientists (male and female) stop consistently rating work based on the gender of the author’s name, and female students stop experiencing grindingly regular demeaning and exclusionary treatment throughout their education, I think we’ll find the situation much improved. Of course, that requires us to be both proactive and self-critical, rather than shrugging our shoulders from a position of privilege and saying “viva la difference.”

  7. Wow! What’s fascinating is that not only should women not complain that they can’t hack it in science, as predicted by their SAT performace compared with males, but a huge majority (>95%) of 18 year olds should be discouraged from futilely attempting to have an academic career…they just don’t have the inherent smarts it takes to get to the top. I mean, even the boys among them are dumber than the few lucky girls who can rotate a complex solid in their heads.

    I guess all these programs that encourage kids to go into science are in vain. We’re already skimming the cream, the rest are a waste. Oh well, the world needs autoclave repair technicians, too…

  8. Differences in SAT test scores are the result of innate differences.

    The SAT mostly measures g, the highest-order factor common to all subtests in a large and diverse battery of mental tests.

    Scholastic Assessment or g? Psychological Science 15, 337 (2004)

    The SAT’s correlations with 7 other traditional IQ tests in this study a non-weighted average 0.74. Its correlation with Raven’s Progressive Matrices, a nonverbal test of inductive reasoning that is widely accepted as a marker of g, is 0.483 (0.72 after correction for restriction of range in ability in this college sample). Based on these data the g loading of the SAT (that is, the correlation of the SAT with the latent construct measured by all IQ tests) probably exceeds 0.80.

    g is highly heritable. At least 70 percent of its variance is attributable to genetic differences in the population.

    Sources of human psychological differences: the Minnesota Study of Twins Reared Apart. Science 250, 223-228 (1990)
    Large, Consistent Estimates of the Heritability of Cognitive Ability in Two Entire Populations of 11-Year-Old Twins from Scottish Mental Surveys of 1932 and 1947. Behavior Genetics 35, 525-534 (2005)
    A Quantitative Genetic Analysis Of Cognitive Abilities During The Second Half Of The Life Span. Psychological Science 3, 346 (1992)

    The narrow-sense heritability of g/IQ (that is, the component of variance transmitted by parents to their offspring) is probably lower than 0.70 but is still substantial.

    Nature, Nurture, And Cognitive Development From 1 To 16 Years. Psychological Science 8, 442 (1997)
    Chapter 4 in Intelligence, Heredity and Environment. eds. Robert J. Sternberg & Elena Grigorenko (Cambridge University Press; January 28, 1997)

    Look at Figure 3 of this paper and note the extremely weak IQ correlation between biologically unrelated adoptive siblings together (r = 0.04, 398 pairs):

    Genetic and environmental influences on human psychological differences. J. Neurobiol. 54, 4-45 (2002)

    Whether the sexes differ in g is a controversial matter that is currently being disputed. It is clear, however, that they do differ in other ability factors measured by standardized tests (e.g., spatial-visualization). Moreover, these other ability factors show incremental validity in the prediction of academic outcomes such as choice of field.

    Importance of Assessing Spatial Ability in Intellectually Talented Young Adolescentes: A 20-Year Longitudinal Study. J.Edu.Psychol. 93, 604-614 (2001)

    Individual differences along these dimensions are heritable independently of g. The most recent analysis of their heritability known to me is contained in this paper:

    Sex differences in mental abilities: g masks the dimensions on which they lie. Intelligence doi:10.1016/j.intell.2006.03.012 (2006)

    Note that the shared environment parameter was dropped from the quantitative-genetic model of the determinants of the lower-order ability dimensions without significant deterioration of model fit. This makes it rather unlikely that whatever causes between-sex differences can be accounted for by environmental differences that vary across families, which include just about every variable that culture-only advocates have invoked.

    I think the fact that a 1 month test-taking course can bump a score by over 100 points scuttles that. As the ETS itself says “it is a myth that a test will provide a unitary, unequivocal yardstick for ranking on merit.” SAT scores also over predict future male performance and underpredict femal performance in university.

    Companies like Princeton Review and Kaplan grossly overhype the effectiveness of their coaching. 100 points is about the most that their programs can boost your score. However, some individuals would have attained gains of that magnitude on their own (because of measurement error or some true change in ability level owing perhaps to maturation), others actually do worse, and others see no effective change. The average gain over all coached individuals is something on the order of 30 points. A review of practice effects on the SAT is included here:

    Straight Talk About Mental Tests. Arthur R. Jensen (Free Press; 1983)

    A more recent study is in accord with past findings:

    Effects of Coaching on SAT I: Reasoning Test Scores. J.Edu.Measurement 36, 93-118 (1999)

    As for differential prediction for males and females, this is confounded by the fact that males and females tend to major in different areas. Statistically adjusting for this disparity substantially reduces differential prediction.

    Students perform lower if their expectations of their own ability are lowered or they are aware of race/gender differences in test outcomes.

    You are referring to “stereotype threat.” First of all, these effects are small and cannot possibly account for the observed group diparities that they are often invoked to explain away. For example, in the MISTRA study referenced above, the male advantage on tests of spatial and mechanial ability exceed one standard deviation, which is far larger than the effect size of stereotype threat. See the highly critical commentary on this research here:

    On Interpreting Stereotype Threat as Accounting for
    African American–White Differences on Cognitive Tests. American Psychologist 59, 7-13 (2004)

    2. The sciences as a whole are made up of people that fall at the far-right edge of whatever cognitive ability curve you’re talking about. (And you have to do better than anecdotes from particular disciplines, like spatial grasp and certain engineering fields.)

    I claim that this has been established beyond any reasonable doubt. Please read the article that I linked to in my previous comment for an introduction to the oceanic literature on this topic. For a more recent article:

    Tracking Exceptional Human Capital Over Two Decades. Psychol.Sci. 17 194 (2006)

    Also, as a sort of experiment, visit the local math department of your nearest top-20 university and try to find out the GRE-Q scores of the graduate students there. I predict that not a single one will have a score one standard error below perfect (about 770). It is even likely that not a single one failed to score a perfect 800.

    3. Academic science is purely meritocratic, and having a bit more of a particular science-related ability will help you have a more successful scientific career (as opposed to, say, the ability to manage a lab full of students and postdocs, grant writing skills, work ethic, ability to get your name on papers with minimal input/effort, writing a lot of reviews, being buddies with journal editors, being a convincing and charismatic advocate of your ideas at conferences, etc, etc…)

    No doubt all these factors orthogonal to cognitive abilities do contribute to success in any field. Yet it remains the case that no other single predictor accounts for as much variance in workplace performance and job knowledge as IQ.

    Handbook of Understanding and Measuring Intelligence. eds. Oliver Wilhelm & Randall W. Engle (Sage Publications, Inc.; 2004) (chapter by Ones)

    If all of these variables could be quantified and entered in a multiple regression with some measure of performance as a criterion variable (e.g., number of publications, tenure/not tenure in a logistic regression), I take it you do not disagree that a measure of cognitive ability would undoubtedly have positive regression coefficients. (Or you shouldn’t, given the evidence that I present next.)

    4. Relatedly, the higher you go up in academic prestige (tenure, promotion) correlates with (let alone is caused by) innate abilites.

    In fact, there is such a correlation. The linear correlation between test scores and criterion variables holds throughout the range of ability, even at the highest levels. The threshold hypothesis implicit in your statement receives no support in the literature that I know of. For a discussion of this matter, see pp. 289-290 here:

    The g Factor: The Science of Mental Ability (Human Evolution, Behavior, and Intelligence). Arthur R. Jensen (Praeger Publishers (1998)

    For a more recent study, see here:

    Creativity and Occupational Accomplishments Among Intellectually
    Precocious Youths: An Age 13 to Age 33 Longitudinal Study. J.Edu.Psychol. 97, 484–492 (2005)

    Two SMPY cohorts, all in the 99th percentile of SAT-M scores as junior high students, were subdivided into quartiles based on SAT-M scores. Even at this extremely high threshold of mathematical ability, the subjects in the upper quartile of the 99th percentile earned more science/math doctorates, earned more doctorates in all fields, enjoyed higher incomes, obtained more patents, and secured tenure at top-50 American universities with greater frequency than their counterparts in the lower quartile.

    why do you find it so easy to dismiss discrimination as a primary cause? Doesn’t it just make sense to work harder toward meritocracy and then see where we stand?

    I do not dismiss discrimination as a cause. My hypothesis is that it is not the only cause. As for working toward meritocracy, Steven Pinker has put it best on
    Edge: The Reality Club:

    I share Nora Newcombe’s desire to move away from a concern with gender differences in mathematical ability to a focus on individuals and how we can maximize their abilities, at least in the spheres of education and public policy. But she does not play out the radical implications of this move. Other than in the context of evolutionary psychology (which elegantly predicts a number of interesting gender differences), a focus on gender differences arises because people ask why the genders are disparately represented in certain walks of life. Almost invariably, disparities in numbers are interpreted as proof of discrimination and discouragement. This, of course, is a fallacy, since the disparities could arise from differences in average temperaments and talents instead or as well. And it’s a fallacy with consequences: if the discrepancies attributed to bias really come from sex differences, then the costly measures designed to counter them (aggressive affirmative action, presumptions of ubiquitous prejudice, re-education programs, diversity bureaucracies, etc.) are misbegotten. If people didn’t obsess over disparities in gender representation in the first place, they would not create the need for researchers to determine whether the disparities may be caused in part by gender differences in ability or interests. So if people want to minimize the importance of the science of gender differences, they should speak out against gender bean-counting in university science departments.

    Thank you for your comments.

  9. Thank you for your detailed reply. First, you refer to various types of longitudinal tracking studies related to precocious kids, who, not surprisingly have dazzling careers in whatever they choose to do relative to average kids. First, it does not logically follow that their subsequent success is wholely attributable to their cognitive abilities. In our society and particularly our schools, “smart” kids are showered with opportunities, encouragement, and confidence-building experiences (smart boys even more so, and it’s christmas every freakin day for smart, upper middle class white boys). Second, noting that smart kids tend to achieve high rank in whatever they do is not even close to the same experiment as testing cognitive ability across, say, the entire academic staff of the U of C system and seeing how well it correlates with rank, citation rate, peer ratings, invitations to speak at conferences, journal editor positions, etc, etc.

    The participation of women in science–and indeed in almost every aspect of our society–has increased steadily for the last few decades. We can say with absolute certainty that this is due to an increase in opportunity and a decrease in discrimination and exclusion. In countries where certain disciplines are less gendered, the participation of women is much higher than the U.S. We also know that our education system still favor boys (preferential treatment by teachers, more parental investment), and that sexual harassment, sexist behavior, and sexual discrimination still occurs within academia.

    In science we look for proximal causes and parsimonious explanations. Sexism and discrimination are a fact, it happens all the time, everywhere. Men and women do it, not because they consciously have unfair assumptions about their colleagues and students, but because they are products of their society. And we know it affects female students and academics in a variety of ways. Why not fix it?

    Pinker’s quote trots out the straw man assumption that the disparity itself is the only evidence we have for discrimination. This is patently false, negated by thousands of sociological studies and the millions of anecdotal experiences of women. Until we have created a meritocracy, citing innate differences as a nebulous first cause in gender disparity is ridiculous and harmful.

    You, I, and even Steven Pinker have no idea what women and minorities are capable of on a level playing field; to claim otherwise is a lie. I’m sure Pinker could tell us some convincing adaptationist stories about why humans instinctively stereotype individuals based on beliefs about groups. Hyping putative innate differences and assigning them more importance than is supported by evidence will directly lead to increased sexism in academia, sexism in primary and secondary classrooms, and the closing of opportunities for thousands of young girls. Science and our society will be poorer for it.

  10. The studies are interesting but most of them seem to provide evidence for something that Barres already grants: that there are some innate differences between male and female brains. What he objects to is using these differences as THE explanation for women’s problems advancing in science.

    Your point 3) is only only weakly supported in the evidence you provide. One citation makes offhand reference to the fact that spatial ability “distinguishes” people in certain disciplines. How essential it is to the actual successful pursuit of those diciplines is left an unanswered question.

    It is certainly possible that spatial ability has become a looked for and tested for quality because it is seen as a more-or-less tribal distinction, rather than exclusively for its on-the-job use value. (See, for instance, medical training, where residencies sometimes seem more to be ritual rites of passage than tests of useful abilities.)

    NOT to say that spatial ability doesn’t matter in science, simply to say that its use to cull candidates may go far beyond what’s merited by it’s actual utility in science.

    So spatial ability distinction granted, you seem streets and streets away from having provided anything like an explanation for the phenomenon under question:

    Do women fail in science because of lack of spatial abilities? Are these spatial insufficiencies 100% innate, or might women’s performance in this area be improved? Do men and women with similar spatial capabilities perform similarly? What reasons are cited by women dropping out of science career paths? Are these related to spatial ability? Do women lag ONLY in fields strongly associated with spatial abilities? etc. etc.

  11. The participation of women in science–and indeed in almost every aspect of our society–has increased steadily for the last few decades. We can say with absolute certainty that this is due to an increase in opportunity and a decrease in discrimination and exclusion.

    What do you exclude from particpation “in almost every aspect of our society”? You seem not to understand the reality of tradeoffs in activities that one chooses to do. Over the last few decades, women have faced intense social pressure to conform to traditional male standards of success, namely, job earnings and status. At least over the past decade, increasing social pressure on women to conform to male standards has probably affected women’s career choices more than discrimination.

    Today, the more children a woman has, the more she is considered benighted. From a historical and evolutionary perspective, that’s amazing.

  12. You are equating expanded access to education and the opportunity to choose from more diverse lifestyles and careers to being “pressured” to conform to male standards? I don’t know how to take that seriously.

  13. Wow. I’m coming late to this thread (thanks Google!), but to the disinterested observer Darth Quixote and godlesscapitalist absolutely dominated here. The objections to their arguments like the one above (“spatial ability” as a “tribal distinction” in science!) are so ad-hoc and desperate as to be laughable.

    On one side we have negative adjectives, on the other side we have science. It’s clear which side has peer-reviewed evidence on its side. Wow, Nature really screwed the pooch on this one by publishing Barres without this counterargument.

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