Paleontologist and evolutionary biologist Stephen Jay Gould (1941–2002) was a professor of geology and zoology at Harvard University from 1967 until his death. His major scientific work was the theory of punctuated equilibrium, a biological theory that builds on the work of Charles Darwin by suggesting that evolution occurs sporadically, rather than gradually over a long period of time. Gould authored numerous books, including The Mismeasure of Man (1981); Wonderful Life: The Burgess Shale and the Nature of History (1989); his magnum opus, The Structure of Evolutionary Theory (2002); and The Hedgehog, the Fox, and the Magister’s Pox: Mending the Gap between Science and the Humanities (2003).

Women’s Brains

Gould wrote for a general audience in his column for Natural History, where the following essay originally appeared in 1980.

In the Prelude to Middlemarch, George Eliot lamented the unfulfilled lives of talented women:

Eliot goes on to discount the idea of innate limitation, but while she wrote in 1872, the leaders of European anthropometry were trying to measure “with scientific certitude” the inferiority of women. Anthropometry, or measurement of the human body, is not so fashionable a field these days, but it dominated the human sciences for much of the nineteenth century and remained popular until intelligence testing replaced skull measurement as a favored device for making invidious comparisons among races, classes, and sexes. Craniometry, or measurement of the skull, commanded the most attention and respect. Its unquestioned leader, Paul Broca (1824–80), professor of clinical surgery at the Faculty of Medicine in Paris, gathered a school of disciples and imitators around himself. Their work, so meticulous and apparently irrefutable, exerted great influence and won high esteem as a jewel of nineteenth-century science.

Broca’s work seemed particularly invulnerable to refutation. Had he not measured with the most scrupulous care and accuracy? (Indeed, he had. I have the greatest respect for Broca’s meticulous procedure. His numbers are sound. But science is an inferential exercise, not a catalog of facts. Numbers, by themselves, specify nothing. All depends upon what you do with them.) Broca depicted himself as an apostle of objectivity, a man who bowed before facts and cast aside superstition and sentimentality. He declared that “there is no faith, however respectable, no interest, however legitimate, which must not accommodate itself to the progress of human knowledge and bend before truth.” Women, like it or not, had smaller brains than men and, therefore, could not equal them in intelligence. This fact, Broca argued, may reinforce a common prejudice in male society, but it is also a scientific truth. L. Manouvrier, a black sheep in Broca’s fold, rejected the inferiority of women and wrote with feeling about the burden imposed upon them by Broca’s numbers:

Broca’s argument rested upon two sets of data: the larger brains of men in modern societies, and a supposed increase in male superiority through time. His most extensive data came from autopsies performed personally in four Parisian hospitals. For 292 male brains, he calculated an average weight of 1,325 grams; 140 female brains averaged 1,144 grams for a difference of 181 grams, or 14 percent of the male weight. Broca understood, of course, that part of this difference could be attributed to the greater height of males. Yet he made no attempt to measure the effect of size alone and actually stated that it cannot account for the entire difference because we know, a priori, that women are not as intelligent as men (a premise that the data were supposed to test, not rest upon):

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In 1873, the year after Eliot published Middlemarch, Broca measured the cranial capacities of prehistoric skulls from L’Homme Mort cave. Here he found a difference of only 99.5 cubic centimeters between males and females, while modern populations range from 129.5 to 220.7. Topinard, Broca’s chief disciple, explained the increasing discrepancy through time as a result of differing evolutionary pressures upon dominant men and passive women:

In 1879, Gustave Le Bon, chief misogynist of Broca’s school, used these data to publish what must be the most vicious attack upon women in modern scientific literature (no one can top Aristotle). I do not claim his views were representative of Broca’s school, but they were published in France’s most respected anthropological journal. Le Bon concluded:

Nor did Le Bon shrink from the social implications of his views. He was horrified by the proposal of some American reformers to grant women higher education on the same basis as men:

Sound familiar?¹

I have reexamined Broca’s data, the basis for all this derivative pronouncement, and I find his numbers sound but his interpretation ill-founded, to say the least. The data supporting his claim for increased difference through time can be easily dismissed. Broca based his contention on the samples from L’Homme Mort alone—only seven male and six female skulls in all. Never have so little data yielded such far-ranging conclusions.

In 1888, Topinard published Broca’s more extensive data on the Parisian hospitals. Since Broca recorded height and age as well as brain size, we may use modern statistics to remove their effect. Brain weight decreases with age, and Broca’s women were, on average, considerably older than his men. Brain weight increases with height, and his average man was almost half a foot taller than his average woman. I used multiple regression, a technique that allowed me to assess simultaneously the influence of height and age upon brain size. In an analysis of the data for women, I found that, at average male height and age, a woman’s brain would weigh 1,212 grams. Correction for height and age reduces Broca’s measured difference of 181 grams by more than a third, to 113 grams.

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I don’t know what to make of this remaining difference because I cannot assess other factors known to influence brain size in a major way. Cause of death has an important effect: degenerative disease often entails a substantial diminution of brain size. (This effect is separate from the decrease attributed to age alone.) Eugene Schreider, also working with Broca’s data, found that men killed in accidents had brains weighing, on average, 60 grams more than men dying of infectious diseases. The best modern data I can find (from American hospitals) records a full 100-gram difference between death by degenerative arteriosclerosis and by violence or accident. Since so many of Broca’s subjects were very elderly women, we may assume that lengthy degenerative disease was more common among them than among the men.

More importantly, modern students of brain size still have not agreed on a proper measure for eliminating the powerful effect of body size. Height is partly adequate, but men and women of the same height do not share the same body build. Weight is even worse than height, because most of its variation reflects nutrition rather than intrinsic size—fat versus skinny exerts little influence upon the brain. Manouvrier took up this subject in the 1880s and argued that muscular mass and force should be used. He tried to measure this elusive property in various ways and found a marked difference in favor of men, even in men and women of the same height. When he corrected for what he called “sexual mass,” women actually came out slightly ahead in brain size.

Thus, the corrected 113-gram difference is surely too large; the true figure is probably close to zero and may as well favor women as men. And 113 grams, by the way, is exactly the average difference between a 5 foot 4 inch and a 6 foot 4 inch male in Broca’s data. We would not (especially us short folks) want to ascribe greater intelligence to tall men. In short, who knows what to do with Broca’s data? They certainly don’t permit any confident claim that men have bigger brains than women.

To appreciate the social role of Broca and his school, we must recognize that his statements about the brains of women do not reflect an isolated prejudice toward a single disadvantaged group. They must be weighed in the context of a general theory that supported contemporary social distinctions as biologically ordained. Women, blacks, and poor people suffered the same disparagement, but women bore the brunt of Broca’s argument because he had easier access to data on women’s brains. Women were singularly denigrated but they also stood as surrogates for other disenfranchised groups. As one of Broca’s disciples wrote in 1881: “Men of the black races have a brain scarcely heavier than that of white women.” This juxtaposition extended into many other realms of anthropological argument, particularly to claims that, anatomically and emotionally, both women and blacks were like white children—and that white children, by the theory of recapitulation, represented an ancestral (primitive) adult stage of human evolution. I do not regard as empty rhetoric the claim that women’s battles are for all of us.

Maria Montessori did not confine her activities to educational reform for young children. She lectured on anthropology for several years at the University of Rome, and wrote an influential book entitled Pedagogical Anthropology (English edition, 1913). Montessori was no egalitarian. She supported most of Broca’s work and the theory of innate criminality proposed by her compatriot Cesare Lombroso. She measured the circumference of children’s heads in her schools and inferred that the best prospects had bigger brains. But she had no use for Broca’s conclusions about women. She discussed Manouvrier’s work at length and made much of his tentative claim that women, after proper correction of the data, had slightly larger brains than men. Women, she concluded, were intellectually superior, but men had prevailed heretofore by dint of physical force. Since technology has abolished force as an instrument of power, the era of women may soon be upon us: “In such an epoch there will really be superior human beings, there will really be men strong in morality and in sentiment. Perhaps in this way the reign of women is approaching, when the enigma of her anthropological superiority will be deciphered. Woman was always the custodian of human sentiment, morality and honor.”

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This represents one possible antidote to “scientific” claims for the constitutional inferiority of certain groups. One may affirm the validity of biological distinctions but argue that the data have been misinterpreted by prejudiced men with a stake in the outcome, and that disadvantaged groups are truly superior. In recent years, Elaine Morgan has followed this strategy in her Descent of Woman, a speculative reconstruction of human prehistory from the woman’s point of view—and as farcical as more famous tall tales by and for men.

I prefer another strategy. Montessori and Morgan followed Broca’s philosophy to reach a more congenial conclusion. I would rather label the whole enterprise of setting a biological value upon groups for what it is: irrelevant and highly injurious. George Eliot well appreciated the special tragedy that biological labeling imposed upon members of disadvantaged groups. She expressed it for people like herself—women of extraordinary talent. I would apply it more widely—not only to those whose dreams are flouted but also to those who never realize that they may dream—but I cannot match her prose. In conclusion, then, the rest of Eliot’s prelude to Middlemarch:

(1980)