It begins with how doctors are trained. Historically it’s been assumed that there wasn’t anything fundamentally different between male and female bodies other than size and reproductive function, and so for years medical education has been focused on a male ‘norm’, with everything that falls outside that designated ‘atypical’ or even ‘abnormal’.1 References to the ‘typical 70 kg man’2 abound, as if he covers both sexes (as one doctor pointed out to me, he doesn’t even represent men very well). When women are mentioned, they are presented as if they are a variation on standard humanity. Students learn about physiology, and female physiology. Anatomy, and female anatomy. ‘The male body’, concluded social psychologist Carol Tavris in her 1992 book The Mismeasure of Woman, ‘is anatomy itself.’3
This male-default bias goes back at least to the ancient Greeks, who kicked off the trend of seeing the female body as a ‘mutilated male’ body (thanks, Aristotle). The female was the male ‘turned outside in’. Ovaries were female testicles (they were not given their own name until the seventeenth century) and the uterus was the female scrotum. The reason they were inside the body rather than dropped out (as in typical humans) is because of a female deficiency in ‘vital heat’. The male body was an ideal women failed to live up to.
Modern doctors of course no longer refer to women as mutilated males, but the representation of the male body as the human body persists. A 2008 analysis of a range of textbooks recommended by twenty of the ‘most prestigious universities in Europe, the United States and Canada’ revealed that across 16,329 images, male bodies were used three times as often as female bodies to illustrate ‘neutral body parts’.4 A 2008 study of textbooks recommended by Dutch medical schools found that sex-specific information was absent even in sections on topics where sex differences have long been established (such as depression and the effects of alcohol on the body), and results from clinical trials were presented as valid for men and women even when women were excluded from the study.5 The few sex differences that did get a mention were ‘hardly accessible via index or layout’, and in any case tended to be vague one-liners such as ‘women, who more often have atypical chest discomfort’. (As we’ll see, only one in eight women who have a heart attack report the classic male symptom of chest pain, so in fact this description is arguably not only vague, but inaccurate.6)
In 2017 I decided to see if much had changed, and set off to a large bookshop in central London with a particularly impressive medical section. Things had not changed. The covers of books entitled ‘Human Anatomy’ were still adorned with be-muscled men. Drawings of features common to both sexes continued to routinely include pointless penises. I found posters entitled ‘Ear, Nose & Throat’, ‘The Nervous System’, ‘The Muscular System’, and ‘The Vascular System and Viscera’, all of which featured a large-scale drawing of a man. The vascular-system poster did, however, include a small ‘female pelvis’ off to one side, and me and my female pelvis were grateful for small mercies.
The gender data gaps found in medical textbooks are also present in your typical medical-school curriculum. A 2005 Dutch study found that sex-and gender-related issues were ‘not systematically addressed in curriculum development’.7 A 2006 review of ‘Curr-MIT’, the US online database for med-school courses, found that only nine out of the ninety-five schools that entered data into the system offered a course that could be described as a ‘women’s health course’.8 Only two of these courses (obstetrics and gynaecology classes taught in the second or third academic years) were mandatory. Even conditions that are known to cause the greatest morbidity and mortality in women failed to incorporate sex-specific information. Ten years later, another review found that the integration of sex-and gender-based medicine in US med schools remained ‘minimal’ and ‘haphazard’, with gaps particularly identified in the approach to the treatment of disease and use of drugs.9
These gaps matter because contrary to what we’ve assumed for millennia, sex differences can be substantial. Researchers have found sex differences in every tissue and organ system in the human body,10 as well as in the ‘prevalence, course and severity’ of the majority of common human diseases.11 There are sex differences in the fundamental mechanical workings of the heart.12 There are sex differences in lung capacity,13 even when these values are normalised to height (perhaps related is the fact that among men and women who smoke the same number of cigarettes, women are 20-70% more likely to develop lung cancer14).
Autoimmune diseases affect about 8% of the population,15 but women are three times more likely to develop one, making up about 80% of those affected.16 We don’t fully know why, but researchers think it might be down to women being the childbearing sex: the theory is that females ‘evolved a particularly fast and strong immune response to protect developing fetuses and newborn babies’,17 meaning that sometimes it overreacts and attacks the body.18 The immune system is also thought to be behind sex-specific responses to vaccines: women develop higher antibody responses and have more frequent and severe adverse reactions to vaccines,19 and a 2014 paper proposed developing male and female versions of influenza vaccines.20
Sex differences appear even in our cells: in blood-serum biomarkers for autism;21 in proteins;22 in immune cells used to convey pain signals;23 in how cells die following a stroke.24 A recent study also found a significant sex difference in the ‘expression of a gene found to be important for drug metabolism’.25 Sex differences in the presentation and outcome of Parkinson’s disease, stroke and brain ischaemia (insufficient blood flow to the brain) have also been tracked all the way to our cells,26 and there is growing evidence of a sex difference in the ageing of the blood vessels, ‘with inevitable implications for health problems, examination and treatment’.27 In a 2013 Nature article, Dr Elizabeth Pollitzer points to research showing that male and female mice cells have been found to respond differently to stress; that male and female human cells ‘exhibit wildly different concentrations of many metabolites’; and to ‘mounting evidence’ that ‘cells differ according to sex irrespective of their history of exposure to sex hormones’.28
There are still vast medical gender data gaps to be filled in, but the past twenty years have demonstrably proven that women are not just smaller men: male and female bodies differ down to a cellular level. So why aren’t we teaching this?
The inclusion of sex-specific information in textbooks is dependent on the availability of sex-specific data, but because women have largely been excluded from medical research this data is severely lacking. Even the very basics of sex determination have a sex data gap: since the landmark 1990 paper that identified the Y chromosome as ‘the’ sex-determining region, the female sex has – the irony – been seen as the default. But in this case, the default didn’t mean we focused on the female. Rather, research instead focused on testes development as the supposedly ‘active’ process, while female sexual development was seen as a passive process – until 2010, when we finally started researching the active process of ovarian determination.29