By 1907, Spitzka could present a tabulation of 115 eminent men. As the list grew in length, ambiguity of results increased apace. At the upper end, Cuvier was finally overtaken when Turgenev broke the 2,000-gram barrier in 1883. But embarrassment and insult stalked the other end. Walt Whitman managed to hear the varied carols of America singing with only 1,282 g. Franz Josef Gall, a founder of phrenology—the original “science” of judging mental worth by the size of localized brain areas—could muster only 1,198 g. Later, in 1924, Anatole France almost halved Turgenev’s 2,012 and weighed in at a mere 1,017 g.
Spitzka, nonetheless, was undaunted. In an outrageous example of data selected to conform with a priori prejudice, he arranged, in order, a large brain from an eminent white male, a bushwoman from Africa, and a gorilla. (He could easily have reversed the first two by choosing a larger black and a smaller white.) Spitzka concluded, again invoking the shade of Georges Cuvier: “The jump from a Cuvier or a Thackeray to a Zulu or a Bushman is no greater than from the latter to the gorilla or the orang.”
Such overt racism is no longer common among scientists, and I trust that no one would now try to rank races or sexes by the average size of their brains. Yet our fascination with the physical basis of intelligence persists (as it should), and the naive hope remains in some quarters that size or some other unambiguous external feature might capture the subtlety within. Indeed, the crassest form of more-is-better—using an easily measured quantity to assess improperly a far more subtle and elusive quality—is still with us. And the method that some men use to judge the worth of their penises or their automobiles is still being applied to brains. This essay was inspired by recent reports on the whereabouts of Einstein’s brain. Yes, Einstein’s brain was removed for study, but a quarter century after his death, the results have not been published. The remaining pieces—others were farmed out to various specialists—now rest in a Mason jar packed in a cardboard box marked “Costa Cider” and housed in an office in Wichita, Kansas. Nothing has been published because nothing unusual has been found. “So far it’s fallen within normal limits for a man his age,” remarked the owner of the Mason jar.
Did I just hear Cuvier and Anatole France laughing in concert from on high? Are they repeating a famous motto of their native land: plus ça change, plus c’est la même chose (“the more things change, the more they remain the same”). The physical structure of the brain must record intelligence in some way, but gross size and external shape are not likely to capture anything of value. I am, somehow, less interested in the weight and convolutions of Einstein’s brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops.
14 | Women’s Brains
IN THE PRELUDE to Middlemarch, George Eliot lamented the unfulfilled lives of talented women:
Some have felt that these blundering lives are due to the inconvenient indefiniteness with which the Supreme Power has fashioned the natures of women: if there were one level of feminine incompetence as strict as the ability to count three and no more, the social lot of women might be treated with scientific certitude.
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:
Women displayed their talents and their diplomas. They also invoked philosophical authorities. But they were opposed by numbers unknown to Condorcet or to John Stuart Mill. These numbers fell upon poor women like a sledge hammer, and they were accompanied by commentaries and sarcasms more ferocious than the most misogynist imprecations of certain church fathers. The theologians had asked if women had a soul. Several centuries later, some scientists were ready to refuse them a human intelligence.
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):
We might ask if the small size of the female brain depends exclusively upon the small size of her body. Tiedemann has proposed this explanation. But we must not forget that women are, on the average, a little less intelligent than men, a difference which we should not exaggerate but which is, nonetheless, real. We are therefore permitted to suppose that the relatively small size of the female brain depends in part upon her physical inferiority and in part upon her intellectual inferiority.
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:
The man who fights for two or more in the struggle for existence, who has all the responsibility and the cares of tomorrow, who is constantly active in combating the environment and human rivals, needs more brain than the woman whom he must protect and nourish, the sedentary woman, lacking any interior occupations, whose role is to raise children, love, and be passive.
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:
In the most intelligent races, as among the Parisians, there are a large number of women whose brains are closer in size to those of gorillas than to the most developed male brains. This inferiority is so obvious that no one can contest it for a moment; only its degree is worth discussion. All psychologists who have studied the intelligence of women,
as well as poets and novelists, recognize today that they represent the most inferior forms of human evolution and that they are closer to children and savages than to an adult, civilized man. They excel in fickleness, inconstancy, absence of thought and logic, and incapacity to reason. Without doubt there exist some distinguished women, very superior to the average man, but they are as exceptional as the birth of any monstrosity, as, for example, of a gorilla with two heads; consequently, we may neglect them entirely.
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:
A desire to give them the same education, and, as a consequence, to propose the same goals for them, is a dangerous chimera…. The day when, misunderstanding the inferior occupations which nature has given her, women leave the home and take part in our battles; on this day a social revolution will begin, and everything that maintains the sacred ties of the family will disappear.
Sound familiar?*
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.
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.”
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:
The limits of variation are really much wider than anyone would imagine from the sameness of women’s coiffure and the favorite love stories in prose and verse. Here and there a cygnet is reared uneasily among the ducklings in the brown pond, and never finds the living stream in fellowship with its own oary-footed kind. Here and there is born a Saint Theresa, foundress of nothing, whose loving heartbeats and sobs after an unattained goodness tremble off and are dispersed among hindrances instead of centering in some long-recognizable deed.
15 | Dr. Down’s Syndrome
MEIOSIS, THE SPLITTING of chromosome pairs in the formation of sex cells, represents
one of the great triumphs of good engineering in biology. Sexual reproduction cannot work unless eggs and sperm each contain precisely half the genetic information of normal body cells. The union of two halves by fertilization restores the full amount of genetic information, while the mixing of genes from two parents in each offspring also supplies the variability that Darwinian processes require. This halving, or “reduction division,” occurs during meiosis when the chromosomes line up in pairs and pull apart, one member of each pair moving to each of the sex cells. Our admiration for the precision of meiosis can only increase when we learn that cells of some ferns contain more than 600 pairs of chromosomes and that, in most cases, meiosis splits each pair without error.
Yet organic machines are no more infallible than their industrial counterparts. Errors in splitting often occur. On rare occasions, such errors are harbingers of new evolutionary directions. In most cases, they simply lead to misfortune for any offspring generated from the defective egg or sperm. In the most common of meiotic errors, called nondisjunction, the chromosomes fail to split. Both members of the pair go to one sex cell, while the other comes up one chromosome short. A child formed from the union of a normal sex cell with one containing an extra chromosome by nondisjunction will carry three copies of that chromosome in each cell, instead of the normal two. This anomaly is called a trisomy.
In humans, the twenty-first chromosome suffers nondisjunction at a remarkably high frequency, unfortunately rather tragic in effect. About 1 in 600 to 1 in 1,000 newborn babies carry an extra twenty-first chromosome, a condition technically known as “trisomy-21.” These unfortunate children suffer mild to severe mental retardation and have a reduced life expectancy. They exhibit, in addition, a suite of distinctive features, including short and broad hands, a narrow high palate, rounded face and broad head, a small nose with a flattened root, and a thick and furrowed tongue. The frequency of trisomy-21 rises sharply with increasing maternal age. We know very little about the causes of trisomy-21; indeed, its chromosomal basis was not discovered until 1959. We have no idea why it occurs so often, and why other chromosomes are not nearly so subject to nondisjunction. We have no clue as to why an extra twenty-first chromosome should yield the highly specific set of abnormalities associated with trisomy-21. But at least it can be identified in utero by counting the chromosomes of fetal cells, thus providing an option for early abortion.
The Panda's Thumb: More Reflections in Natural History Page 14