Bad Science and the Unisex Brain

BOOKS & ARTS COMMENT

so can reach vast dimensions — as in the NEUROSCIENCE blue whale. This narrative is neatly done, but the fascination exerted by human bone on human minds lies at the book’s heart. Bad science and With Switek, we visit Neolithic tombs and medieval ossuaries, consider skull cults and muse on the bony personifica- tion of Death. The book makes extended the unisex brain explorations of how nineteenth-century anthropologists such as Samuel Morton in Philadelphia, Pennsylvania, used skull The hunt for differences between men’s and women’s measurements to claim the existence of brains is full of poor research practice, writes Lise Eliot. racial differences, a malign legacy that, although long discredited in science, lingers today in apologias for racism. arly in The Gendered Brain, cognitive shows, this hunt for Switek also describes the protracted neuroscientist Gina Rippon brain differences tug-of-war between scientists and the describes one of the myriad brain “has been vigorously Native American community around Estudies heralded as ‘finally’ explaining pursued down the the Columbia River in Washington state the difference between men and women. ages with all the tech- over who owns the 9,000-year-old skel- It was a magnetic resonance imaging niques that science eton of the Ancient One, also known as (MRI) analysis of 21 men and 27 women could muster”. And Kennewick Man (D. H. Thomas Nature by researchers at the University of Califor- it has exploded in the 531, 302–303; 2016). This is terrain most nia, Irvine (R. J. Haier et al. NeuroImage 25, past three decades, palaeontologists never navigate; Switek 320–327; 2005). Tiny by today’s standards, since MRI research picks through it well. this brief communication nonetheless went The Gendered joined the fray. Brain: The New In the book’s coda, the narrative gets on quite a publicity tour, from newspapers Neuroscience That Yet, as The Gen- up close and personal. Switek consid- and blogs to television, books and, even- Shatters The Myth dered Brain reveals, ers his own skeleton, and how it might tually, teacher education and corporate Of The Female conclusive findings follow those of the dinosaurs into geo- leadership conferences. Brain about sex-linked logical immortality. Switek’s deep-time I woke one morning in 2010 to see an GINA RIPPON brain differences focus comes through a little too strongly, especially bad extrapolation of this study The Bodley Head have failed to mat I think, in his assertion that it is mainly on the Early Show, a programme on US (2019) erialize. Beyond the our skeletons that will be left to tell of television network CBS. The presenter, “missing five ounces” our passing. Harry Smith, gushed as medical corre- of female brain — gloated about since “Bone’s Of the detritus spondent Jennifer Ashton declared that the nineteenth century — modern neu- potential that each of us men have “six-and-a-half times more roscientists have identified no decisive, for physical casually scatters grey matter” than women, whereas women category-defining differences between immortality — thousands of have “ten times as much white matter” as the brains of men and women. In women’s reminds us all ballpoint pens, men. Next came the obvious quips about brains, language-processing is not spread too vividly of polyester socks, men’s talent at mathematics and women’s any more evenly across the hemispheres our personal aluminium cans uncanny ability to multitask. Never mind than it is in men’s, as a small 1995 Nature mortality.” and so on — that these differences would demand that study proclaimed but a large 2008 meta- much is a good women’s heads were about 50% larger, or analysis disproved (B. A. Shaywitz et al. deal more decay-resistant than the aver- that the Irvine team didn’t even compare Nature 373, 607–609 (1995) and I. E. Som- age cranium or femur. Our bones might brain volumes, but investigated a correla- mer et al. Brain Res. 1206, 76–88; 2008). be only a small part of our ultimate legacy. tion between IQ and measures of grey or Brain size increases with body size, and Nevertheless, as this book shows, the white matter. certain features, such as the ratio of grey skeletal side of life grips us now, and might to white matter or the cross-sectional area enthral whoever excavates our remains NEUROSEXISM of a nerve tract called the corpus callo- in the far future. As Switek ponders the The history of sex-difference research is sum, scale slightly non-linearly with brain sediments in which his own bones might rife with innumeracy, misinterpretation, size. But these are differences in degree, be fossilized, he needs to think of larger publication bias, weak statistical power, not kind. As Rippon notes, they are not geological processes. The sea floor off the inadequate controls and worse. Rippon, a seen when we compare small-headed shore of New Orleans, Louisiana, might leading voice against the bad neuroscience men to large-headed women, and have no provide a good start: there are stagnant of sex differences, uncovers so many exam- relationship to differences in hobbies or muds, and local tectonic subsidence will ples in this ambitious book that she uses take-home pay. allow the fossil to be securely entombed. a whack-a-mole metaphor to evoke the In the meantime, we should enjoy Switek’s eternal cycle. A brain study purports to HISTORY OF BIAS talent for spinning compelling tales of old discover a difference between men and Rippon’s central message is that “a bones. ■ women; it is publicized as, ‘At last, the gendered world will produce a gendered truth!’, taunting political correctness; other brain”. Her book stands with Angela Saini’s Jan Zalasiewicz is professor of researchers expose some hyped extrapola- 2017 Inferior and Cordelia Fine’s 2010 palaeobiology at the University of tion or fatal design flaw; and, with luck, the Delusions of Gender in rooting out the Leicester, UK. With Mark Williams, he is faulty claim fades away — until the next “neurosexism” that has pervaded attempts author of Skeletons: The Frame of Life. post hoc analysis produces another ‘Aha!’ to understand difference at the brain level. e-mail: [email protected] moment and the cycle repeats. As Rippon It’s a juicy history that would make for

COMMENT BOOKS & ARTS super-fun reading, if it were all truly in the past. Sadly, the moles keep surfacing. Rippon begins with an 1895 quote from social psychologist Gustave Le Bon, who K H FUNG/SPL used his portable cephalometer to declare that women “represent the most inferior forms of human evolution”. She ends in 2017, with Google engineer James Damore blogging to co-workers about “biological causes” for the dearth of women in tech and leadership roles. As Rippon shows, the hunt for proof of women’s inferiority has more recently elided into the hunt for proof of male– female ‘comple- mentarity’. So, this “The brain is line goes, women no more are not really less gendered intelligent than men, just ‘differ- than the liver ent’ in a way that or kidneys happens to coin- or heart.” cide with biblical teachings and the status quo of gender roles. Thus, women’s brains are said to be wired for empathy and intuition, whereas male brains are supposed to be optimized for reason and action. This was how researchers at the Uni- versity of Pennsylvania in Philadelphia framed a highly touted 2014 MRI study that seared into the public imagination a picture of men’s and women’s brains as diametrically opposed subway maps: the connections in women are mostly between hemispheres, and those in men within them (M. Ingalhalikar et al. Proc. Natl Acad. Sci. USA 111, 823–828; 2014). However, the map omits the vast majority of connections that did not differ between the study’s adolescent participants; nor did it control for puberty-related maturation An artificially coloured 3D magnetic resonance imaging scan of a human brain. or, once again, for brain size, all of which reduces apparent male–female difference. science and a masculine stereotype of “bril- 443, 634; 2006). Or perhaps it’s to under- liance” — has impeded their entry into, score how ‘the female brain’ has been sized CULTURAL PATHS and advancement across, this high-status up as a strange variant of the real thing, So if it’s not brain hard-wiring, how do realm. Talented women are regarded as much as we refer to a ‘female physicist’ or we explain the often stark differences in “workhorses”, men as “feral geniuses”, a dis- ‘female surgeon’. behaviour and interests between men and tinction that children internalize by the age Whatever the subtitle, the book women? Here is where we get to Rippon’s of six, according to research by Lin Bian, accomplishes its goal of debunking the thesis on the impact of a gendered world Sarah-Jane Leslie and Andrei Cimpian concept of a gendered brain. The brain is on the human brain. She builds her case in (L. Bian et al. Am. Psychol. 73, 1139–1153; no more gendered than the liver or kidneys four loosely defined parts, from the sordid 2018). And all of this factors into the brain- or heart. Towards the end, Rippon flirts history of sex-difference research through building cycle of differential expectations, with the implications of this finding for the modern brain-imaging methods, the emer- self-confidence and risk-taking that drives growing number of people transitioning gence of social cognitive neuroscience and boys and girls down different trajectories or living between current binary gender the surprisingly weak evidence for brain of career and success. categories. But for now, she concludes, most sex differences in newborns. Rippon shows of us remain strapped in the “biosocial how children’s “cerebral sponges” probably CHANGING MINDS straitjackets” that divert a basically unisex differentiate thanks to the starkly pink-ver- This final focus explains the book’s subtitle, brain down one culturally gendered pathway sus-blue cultures in which they are soaked ‘The New Neuroscience that Shatters the or another. ■ from the moment of prenatal sex reveal. Myth of the Female Brain’. For a volume Part 4 brings us into the twenty-first about debunking brain difference, why Lise Eliot is professor of neuroscience at century, although not to any happy end- narrow it to women? At first, I thought it the Chicago Medical School of Rosalind ing. It focuses on women in science and was a stab at Louann Brizendine’s 2006 The Franklin University of Medicine and technology, and how the gendered world Female Brain, skewered in these very pages Science in North Chicago, Illinois. — including the professionalization of (see R. M. Young and E. Balaban Nature e-mail: [email protected]

454 | NATURE | VOL 566 | 28 FEBRUARY 2019©2019 Spri nger Nature Li mited. All ri ghts reserved. ©2019 Spri nger Nature Li mited. All ri ghts reserved. CORRECTION The article ‘Bad science and the unisex brain’ (Nature 566, 453–454; 2019) included incorrect wording on the effects of brain size: in fact, differences are not seen between small-headed men and large- headed women.