On Setting The “Universal Sex Difference” Bar Way Too Low

This post was co-written by Veronica Berglyd Olsen and Will Robertson.

Studies about brains, gender, and sex always seem to make headlines somewhere. Recently, the Washington Post and many other news sources reported a new study that found brains don’t belong to either a distinct “male” or “female” category: instead, our brains are a big continuum or “mosaic” of features.

This… is not really news. Not if you follow gender and neuroscience anyway. But maybe the last thing you read was about how male and female brains are wired differently, then got lazy/busy/distracted and didn’t read all the follow-up articles about how that splashy study was poorly constructed, and how the conclusions drawn by the researchers and the media were problematic.

In many ways, following the neuroscience of gender is a little like following the “is coffee good for you” debate: if all you do is scan the major headlines, your head would be snapping back and forth like you were watching a ping pong match close up. It’s best to back up so you can look at the whole table without getting whiplash.

This most recent study is not without pushback, however. Over on Psychology Today, David Schmitt has taken issue with what he sees as the broader attempt to “make sex differences disappear”.

From his article:

“Too far, statistically contrived, and scientifically dangerous. The views of Joel et al. represent the polar opposite of where sexual science is going, as evidenced by the National Institutes of Health’s recent declaration that biological sex differences are so large and consequential that both males and females must be included in studies involving cells and non-human animals and in preclinical research. Let us hope sexual scientists keep their eyes on where science is really going, rather than the abracadabra analyses that misleadingly convey there are no important sex differences.”

Whoa there, fella! This is a paper on how brains can’t be categorically shuffled into “male” or “female”, and doesn’t say anywhere that we should stop studying both sexes in medical research. In particular, it’s important that drug and toxicology studies are done on both men and women: the average man’s hormonal cocktail differs enough from the average woman’s that it can impact our health and medical profiles, for example. These differences between our bodies often do impact how we experience disease, and how we respond to treatment. And because we’re twitchy about testing drugs on pregnant women, we have no idea how many drugs and treatments might affect them or their unborn babies.

When you dig into the bulk of his post, and the citations throughout it, he’s not really talking about medical research, or neuroscience specifically: he’s mostly pointing to psychological and behavioural research to support his thesis that men and women are “universally different”.

“Empirically, Hyde (2014) reviewed 100s of studies on psychological sex differences and concluded there are relatively moderate to large sex differences in spatial rotation abilities, agreeableness, sensation seeking, interests in things versus people, physical aggression, certain sexual behaviors (e.g., masturbation and pornography use), and attitudes about casual sex. Smaller sex differences exist in measures of gregariousness, reward sensitivity, conscientiousness, negative affectivity, relational aggression, and self-esteem.

“Some of these sex differences persisted or varied in size across cultures and time periods, others did not (see Lippa, 2009). Ellis (2011) examined psychological sex differences across cultures and found evidence 65 apparently universal sex differences, prevalent across all cultures. These sex differences were universal across all cultures, with not a single replication failure across 10 studies (probably too tough a criterion leading to an under-reporting of actual psychological sex differences).

“Schmitt (2014) found most psychological sex differences are larger in more gender egalitarian cultures, and smaller in more patriarchal cultures, directly refuting the view psychological sex differences are learned because they emerge more strongly in patriarchal cultures that have more extreme sex-role socialization (see also Udry, 2000). Indeed, psychological sex differences seem to emerge most strongly in the most gender-egalitarian of cultures (e.g., Northern Europe), cultures that allow people to pursue the lived experiences they most want to pursue (see also, Schwartz & Rubel-Lifschitz, 2009).”

We dug through the papers referenced in this section, and weren’t terribly impressed. There were a lot of assumptions and a lot of speculation. They were primarily psychological studies, with data collected from questionnaires and mined from large datasets, that attempted to break down behaviors and values along gender lines.

The 2014 Hyde paper, “Gender Similarities and Differences”, summarizes and reviews the current major theories, statistical methods, and conclusions of some recent research, then suggests future research directions based on this review. It doesn’t really claim anything on its own: it’s primarily a summary of other people’s work and findings. There aren’t really any significant conclusions drawn nor critiques made here.

Reading the 2011 Ellis meta study, “Identifying and explaining apparent universal sex differences in cognition and behavior”, we were highly suspicious of their selection criteria specified in the introduction. They only appeared to evaluate the studies on statistical significance, not the quality of the study to control for unintentional bias and stereotype threat. The bulk of the paper – discussing the apparent “universal” sex differences found – is highly speculative and mostly unsourced. Not exactly something rock solid conclusions are made from.

Ellis notes a couple of known alternative hypothesis for lack of sex difference in passing, but both misrepresents and then dismisses them without offering much to justify this rejection other than tautology. These other theories didn’t predict what he believes he sees, so out they go, without much question of whether what he thinks he sees is actually what’s there.

The 2009 Lippa paper “Sex differences in sex drive, sociosexuality, and height across 53 nations: Testing evolutionary and social structural theories” is based entirely off a data set from the BBC. There were over 250,000 respondents from around the world, but since the survey was English-language only, over 83% came from a combination of the UK, the US, Canada, and Australia, with another 6% coming from Western Europe. Most other countries were represented with ridiculously small sample sizes: 25 female and 25 male responses was all it took to get a country included.

Call us sticklers, but we don’t think you can declare human universals because the BBC did an internet survey, where only people who spoke English responded.

Also, it’s important to note you can probably find a study that backs your opinion that almost any gendered trait or behavior is “universal” or “inherent”, and then turn around and find another study that refutes this idea. Here’s a recent giant metasynthesis on 106 meta-analyses and 386 meta-analytic effects on behavioral gender differences: they found few genuinely significant differences emerge, and the top 10 differences could arguably be tied to socialization.

Table 3 from 'Evaluating gender similarities and differences using metasynthesis'. Zell, Ethan; Krizan, Zlatan; Teeter, Sabrina R. American Psychologist, Vol 70(1), Jan 2015, 10-20.

Table 3 from “Evaluating gender similarities and differences using metasynthesis”.
Zell, Ethan; Krizan, Zlatan; Teeter, Sabrina R.
American Psychologist, Vol 70(1), Jan 2015, 10-20.

As Cordelia Fine argued in response to the “our brains are wired differently” study of 2013:

“…the social phenomenon of gender means that a person’s biological sex has a significant impact on the experiences (including social, material, physical, and mental) she or he encounters which will, in turn, leave neurological traces.

“Yet the researchers do not pay any attention to the gendered experiences (such as hobbies, subjects studied at school or higher education, or participation in sporting activities) of the young males and females in their sample.

“This absence has two consequences. First, the researchers miss an opportunity to investigate whether gendered experiences might influence brain development and enhance the acquisition of important skills valuable to all. The second consequence is that, by failing to look at gendered social influences, the authors guarantee that no data will be produced that challenge the notion of “hardwired” male/female neural signatures.”

Our early experiences change our behaviors, change our values, and may even influence the way our brains develop. Teasing apart the “nature versus nurture” knots when it comes to gender – a label we usually get from birth that comes with a lot of cultural baggage and socialization cues – is extraordinarily difficult.

The Udry reference is to a somewhat controversial paper, “Biological limits of gender construction”, published in the 2000 American Sociological Review. The year after, they published several critiques (here, here and here), a response to those critiques from Udry, and a response from the editor on the ASR review process. We also read the paper, and agree there are some major problems with the methodology. There’s a damn fine methodological critique of this paper by Gayathiri Ganeshan up on Academia.edu which is both concise and accessible that covers pretty much everything we would like to say.

The Schmitt reference points to what appears to be his own book chapter. We read that too. It cites a lot of stuff and we obviously couldn’t read through every citation, but it heavily references a couple of the studies we already mentioned, as well as the Schwartz/Rubel-Lifschitz paper titled “Cross-national variation in the size of sex differences in values: Effects of gender equality”.

This paper looks at specific “gendered” values such as “benevolence”, “power”, and “security”. It is survey-based, and while the sample size is pretty large it’s not terribly diverse. One data set draws primarily from European and Scandinavian countries, with a few outliers – Turkey, Israel, Slovakia, Slovenia, and Ukraine – thrown in. The second draws from college and university students from 68 countries between 1988 – 2005. Overall, sifting through the numbers in the appendix, European, Scandinavian, and English speaking countries are pretty vastly over-represented.

They created a “gender equality” score for each country using a mixture of data (it’s not entirely clear how this was created), then compared the gendered “values” revealed in each country’s responses with their “gender equality” score. The idea being that more egalitarian societies will show a smaller difference in gender values. What they find is the differences get larger, and conclude these gendered traits are thusly universal.

The idea that choices people make when seemingly free somehow proves these differences are universal and innate is severely lacking in critical analysis. They become convenient arguments because they fit the preferred model.

There is huge social pressure and expectations on boys and men in many cultures to be “aggressive”, to show no emotion, unless it’s anger, to be the primary breadwinner, to be ambitious. On the other side, women feel a huge social obligation to be mothers, to be warm, to smile, to be caregivers, and to be empathetic. From early on in our lives we’re surrounded by these values and expectations, and our urge to fit in and be “normal” often pushes us into certain interests, certain careers, and certain lifestyles.

What Does “Universal” Really Mean?

The biggest thing that bothered us in this article and in the papers we read was the assumed definition of “universal”, and low standard set for what makes the cut.

Something that is truly “universal” has a high bar to reach, and many of those things that are truly universal are so basic as to be uninteresting; for example, all humans require food and water. What’s interesting is the various things humans do with food and water, and/or how the prevalence of particular kinds of foods in different societies shapes biology in different ways. Margaret Lock calls this “local biologies”: even the very biological processes people think of as universal are not universal, but are always already tied up with sociocultural and environmental milieu.

Sometimes people say “universal” when they mean “nearly universal” or simply “ubiquitous”. Often when we see such claims they’re based on a small sample, or there are issues with data collection, specifically presentism or ethnocentrism. The ethnographic and historical records demonstrate wild variation in sex/gender/sexuality across societies, most of which do not fit our contemporary understandings of these phenomena. But we’re really good at fitting them into our current models and making them seem like there is no difference. And don’t forget: patriarchal social systems are widespread and have been for a long time, so it should be no surprise when the cultural hangover from it lingers, even in countries that are working to counteract its effects.

Sometimes the social sciences can be really sloppy with what qualifies as good data and proof. We understand that applying the same standards as are applied in so-called “hard” sciences is nearly impossible, due to the nature and complexity of the things being studied, but the conclusions should also reflect that. That includes the sloppy usage of statistics, that David Schmitt accuses others of, and also does himself.

None of the studies referenced in this article that we looked at convinced us any gendered behaviors or traits are universal, and they certainly don’t provide any convincing mechanisms by which these traits should fall across gendered lines even if they are.

We also think that bashing a study about how brains can’t be empirically or reliably categorized by gender by claiming it’s trying to ignore medically relevant gender differences, then launching into a tirade about how solid the decidedly shaky evidence is for “universal” gendered behaviors is bullshit. That’s clearly not what the Joel et al. study was about.

If you’re keen and want to read more about gender, brains and behavior, here are five awesome books we recommend that step back from the ping pong table and show you the bigger picture.

Featured image of neural pathways in the brain from NICHD/P. Basser.

Rachelle Saunders

Rachelle is the producer and one of the hosts of "Science for the People", a syndicated radio show and podcast that broadcasts weekly across North America. It explores the connections between science, pop culture, history, and politics. By day she slings code as a web developer and listens to an astonishing number of podcasts.

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One Comment

  1. Cultural differences are a big problem. Like, obviously women’s swimwear is higher-cut than men’s in the West, for the most part. But then you have, like in my culture, when it got hot (The climate in South Dakota is highly variable depending on the time of year.), men would shed clothing faster than women, whose dresses really hid any curves. (Seriously, have you ever worn animal skins? You’ll see what I mean.)

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