First, let's point out that the "journalist/investigator" whom we follow in the "documentary", Harald Eia, is not actually trying to "inform himself" (and he's not a journalist) - he is an active proponent of the theory that biology leads to differences in behavior and interests between men and women, including in terms of career paths. He has, in fact, published a book defending these views (EIA, Harald, IHLE, Ole-Martin (2010), Født sånn eller blitt sånn?). He has confirmed in an interview that he held these views prior to making the "documentary", and that they came to him notably after reading authors like Steven Pinker and David Buss (see his interview here). So let's keep in mind that, contrary to what is being shown on screen, this guy is absolutely not genuinely trying to get a better idea of the issue and weighing what different experts are telling him - he has already made up his mind and the entire documentary is constructed to convince the audience of the validity of the views he holds. That is why he ends the documentary by showing the expert in gender studies seemingly unable to answer what is put forward by the experts in psychology and human evolution he carefully selected.

This being said, what is the validity of the "expert opinions" he relies on to assert that biology leads to men and women essentially having different brains? One of the cornerstones of his demonstration is the opinion of Simon Baron-Cohen, which he goes into great length to present as a legitimate scientific authority (shots of the University of Cambridge where he works, etc.), and Baron-Cohen's study on what he says are 24 hrs-old male and female babies. According to Baron-Cohen, his study shows that babies with virtually no amount of socialization through culture still act differently based on their sex: male babies will tend to be more interested by the movement of a mechanical object and female babies by a human face. Let's start by pointing out that the "mechanical object" referred to here is actually a ball on which were pasted bits of a photograph of a human face - not exactly the type of "mechanical object" that some argue boys are naturally more interested in than girls. Second, the babies were not actually a day old but, on average, 36,7 hrs old - we do not know more from the information given in the study, but the difference is far from being negligible in terms of child development, and culture can already have started to have an impact at that point.

More importantly, however, the study does not, in fact, show statistically significant differences between the sexes in terms of interest in the human face, and does not show a statistically significant preference among boys in favor of the mobile object. There were 58 girls and 44 boys selected for the study, and the numbers in terms of time spent watching each stimulus are simply too close in both cases. Looking at confidence intervals clearly shows that the differences are not statistically significant. To mention the numbers themselves, boys spent around 51-52 seconds looking at the mobile object and around 46 seconds looking at the face. Girls spent barely more time than the boys looking at the face: just below 50 seconds. From a scientific point of view, these differences are non-existent because they are, again, not statistically significant.

If you look at the numbers even further, you'll notice that, beyond the averages put forward by the authors (Baron-Cohen was not alone in writing the study), 64% of the girls did not manifest a preference for the face, and 57% of the boys did not manifest a preference for the mobile object (these percentages include those who manifested a preference for the other stimulus and those who manifested no preference for either). I'll let that sink in. In the documentary (and, in fact, in the article itself), Baron-Cohen deliberately chose to look at the results which seemed to go this way (for example, girls did spend on average more time watching the mobile stimulus than the face - even though the difference was less than 10 seconds between the two), and presented interpretations that went way beyond, and were actually contradicted by, the very results of his experiment. An assertion of the type that "girls preferred the face" and "boys preferred the mobile" is actually false for a majority of both groups. In addition to these problems with the interpretation of the results, several methodological biases and problems have been pointed out with regards to the study, including actual mistakes in the statistical analysis of the results - see NASH, Alison Nash, GROSSI, Giordana (2007), "Picking Barbie’s brain: inherent sex differences in scientific ability?".

Beyond these numbers, which do not support what is said in the documentary, it's also worth mentioning that the authors apparently did not keep the actual data (or at least they're unwilling to share it), and the results they cherry-pick to support their idea that biology plays a major role have never been strictly reproduced. In fact, they've been contradicted by other studies - see SPELKE, Elizabeth (2005), "Sex differences in intrinsic aptitude for mathematics - A critical review", American Psychologist, 60(9), pp. 950-958 and Paola Escudero et al., "Sex-related preferences for real and doll faces versus real and toy objects in young infants and adults", Journal of Experimental Child Psychology, Vol. 116, No. 2, October 2013, pp. 367-379.

To put Baron-Cohen's opinion back into context as well, he did not - contrary to what Harald Eia asserts in the documentary - happen to coincidentally discover what he presents as a difference between sexes in his study. In fact, Baron-Cohen formulated several years prior to the study his personal theory of autism as an extreme form of the natural cerebral masculinity which he posits the existence of. His theory notably included some of what is mentioned in the "documentary" in terms of a link between testosterone levels and differences in cognitive dispositions with regards to the spatial and the social among males and females. In his following research, therefore, he tried to prove this theory of his, and the study referred to here is part of that effort. He had a prior interest in presenting certain specific results and not simply an interest in discovering what results he could find. In the scientific field on autism, his theory on "essential" differences between female and male brains is absolutely not consensual (and, in fact, rather unpopular if we look at citations).

I explored the detail of this specific part of the documentary, but similar comments can be made with regards to the other testimonies defending the existence of a biological determinism separating male and female brains in a way that leads to differences in interests and even career paths. The social scientist interviewed at the beginning which says that there is no actual scientific evidence of such biological determinism is actually perfectly right. They were not very articulate at the end (I suspect that there might have been a bias in the selection of footage to show for their answers at the end, but oh well), but the fact is simply that the scientific research done so far does NOT establish the existence of such biological determinism. There have been articles claiming to establish such differences, such as Baron-Cohen's, but they do not resist scrutiny and are systematically characterized by methodological biases/flaws and interpretation problems. In fact, if you want a very extensive look at the literature on the topic, I suggest you read Rebecca M. Jordan-Young's book Brain Storm: The Flaws in the Science of Sex Differences (2010), it's extremely exhaustive and well-documented. Her conclusions include that we are not blank slates (predispositions are not completely identical in individuals) but that the binary system of gender does not accurately capture these initial differences (see also WITELSON, S. F. (1991), "Neural Sexual Mosaicism: Sexual Differentiation of the Human Temporo-Parietal Region for Functional Asymmetry". Psychoneuroendocrinology, 16 (1-3): pp. 131-153). Clearly, cultural factors are a driving force behind differences in career paths between men and women, and social construction of gender roles is a fundamental object of study for whomever is interested in more equality between sexes.

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