By Amishi Patil
There is a popular myth that claims that men and women’s brains process information differently, which can lead to different decision making, thinking, learning, etc. In our daily lives, we often hear that men are more “logical” and women are more “emotional”. However, scientific research does not support the distinction between the “male” and “female” brain. This idea is a myth that society uses to perpetuate gender norms and stereotypes.
There is a partial truth to the myth that scientific research has identified average structural and biochemical differences between male and female brains. For instance, Ingalhalikar et al. (2014) found that in supratentorial regions, an area of the brain responsible for higher cognitive functions, males tended to show greater within-hemispheric connectivity, whereas females showed stronger between-hemispheric connectivity. Other research has shown that, on average, males have larger total brain volumes than females (Ruigrok et al. 2014). These structural differences could lead to downstream effects on how certain cognitive processes are exhibited and processed. In addition, studies have reported sex differences in the functioning of neurotransmitters and hormones like dopamine and serotonin, which may influence aspects of brain function and behavior (Nishizawa et al.,1997). These findings provide insight into evolutionary history, neurodevelopment, and therapeutic outcomes. However, it is important to consider that these results represent averages. They do not imply that men and women’s brains are distinct, or that these differences translate into differences in cognitive abilities or information processing. This is because these averages represent trends across large groups. Many characteristics, like connectivity and levels of neurotransmitters, exist on a continuum, not in distinct groups between males and females.
This myth is rooted in a long history of attempts to not only understand the brain, but explain the social roles of men and women. Historical narratives have often suggested that there are innate differences between the sexes that justify their positions in society. Ancient Greek philosophers, such as Aristotle, believed that male and female bodies were fundamentally different and linked specific behavioral traits to gender. Although these theories did not yet involve the brain, it laid the foundation for associating men with logic, leadership, and higher societal roles, while women were depicted as more emotional and wired for empathy.
As more people began investigating sex differences, preconceived notions spearheaded their approach to research. Oftentimes research was conducted and published to fit these pre-existing biases, relying on weak statistical significance, inadequate controls, and innumeracy to further perpetuate this myth. Additionally, publications that supported this theory were favored, creating a skewed literature.
With the rise of neuroscience and new technologies, a modern form of bias has emerged: “neurosexism”. Cognitive neuroscientist Gina Rippon describes it perfectly: “a gendered world will produce a gendered brain,” highlighting that social expectations shape the interpretation of findings fueling this myth (Waldman, 2019).
Some research has been misused to reinforce sex-based differences in intelligence. For example, Haier, Jung, Yeo, Head, & Alkire (2004) examined structural brain variations alongside IQ scores and found that men and women achieve similar results in intelligence tests but rely on different brain regions to do so. This showcases there is no single neuroanatomical structure for general intelligence. Additionally, the Geschwind-Galaburda hypothesis in the 1980s reported that higher prenatal testosterone in males slowed the development of the left brain hemisphere, which resulted in greater laterization in this area. Lateralization refers to one hemisphere dominating functions more, for example skills like language which perpetuated the narrative that men were more logical and smarter (Haier et al., 2004). However, more recent research found that there is no significant sex difference in the extent of left hemisphere lateralization. The research findings in this area of study are overly simplified to fit the belief that there were sex differences. However, they depict an important point: while structural brain differences between sexes may exist, they do not necessarily translate into functional differences in cognitive ability. Furthermore, methodological issues skew the interpretation of these studies. Brain size correlates with body size, meaning men who tend to have larger bodies and, therefore, larger skulls are more likely to show structural differences compared to women with smaller skulls. When data is not properly normalized, results can be skewed in ways that reinforce stereotypes, such as the false idea that larger male brains equate to superior cognitive abilities compared to females.
So to answer the question – what is the truth and do we know it? Current research shows that whilst there are sex-based differences on average, there is not enough strong evidence to show that there are male and female brains. For example, Joel et al. (2015) conducted a study analyzing MRIs from 1400 human brains and found that there is an extensive overlap between “distribution in gray matter, white matter and connections” of both sexes. They also found that features that embody “maleness” or “femaleness” are rare and our brains are a “mosaic of features some more common in males compared with females and some common in males and females”. There is more emerging research just like this across larger populations and cultures that highlight the truth that there is no “male” or “female” brain (Eliot, 2024). Our brains are adaptive and change as we grow; whilst differences between genders can be observed, there are also differences based on experiences. Neuroplasticity plays a critical role in shaping our brains structure and functions to help us be the most adaptive versions of ourselves. I think the more significant question is what the implications of neurosexism are, who benefits, and how we can tackle this. Research in the field of neuroscience is supposed to educate us in the ways our mind and brains work to overcome challenges in every facet of our lives. Not just in healthcare, but politics, economics, sports, etc. It should not be used to perpetuate the idea that there is a superior gender, race or being. This myth is rooted in history, culture and stereotypes more than scientific evidence. Whilst small sex differences exist on average, they are too subtle to support the claim that there are two different types of brains in males and females. In fact, more variation occurs within each sex than between them, as a result they don’t result in distinct differences. Our human brains are diverse and resilient and shaped by experiences and biology, not gender.
References
Eliot, L. (2019, February 27). Neurosexism: The myth that men and women have different brains. Nature, 566, 453–454. https://doi.org/10.1038/d41586-019-00677-x
Eliot, L. (2024). Remembering the null hypothesis when searching for brain sex differences. Biology of Sex Differences, 15, Article 14. https://doi.org/10.1186/s13293-024-00585-4
Haier, R. J., Jung, R. E., Yeo, R. A., Head, K., & Alkire, M. T. (2004). The neuroanatomy of general intelligence: Sex matters. Brain Research Bulletin, 62(3), 311–315. https://doi.org/10.1016/j.brainresbull.2003.11.001
Ingalhalikar, M., Smith, A., Parker, D., Satterthwaite, T. D., Elliott, M. A., Ruparel, K., Hakonarson, H., Gur, R. E., Gur, R. C., & Verma, R. (2014). Sex differences in the structural connectome of the human brain. Proceedings of the National Academy of Sciences of the United States of America, 111(2), 823–828. https://doi.org/10.1073/pnas.1316909110
Joel, D., Berman, Z., Tavor, I., Wexler, N., Gaber, O., Stein, Y., Shefi, N., Pool, J., Urchs, S., Margulies, D. S., & Assaf, Y. (2018). Sex beyond the genitalia: The human brain mosaic. Proceedings of the National Academy of Sciences of the United States of America, 115(41), 10420–10425. https://doi.org/10.1073/pnas.1712325115
Nishizawa, S., Benkelfat, C., Young, S. N., Leyton, M., Mzengeza, S., de Montigny, C., Blier, P., & Diksic, M. (1997). Differences between males and females in rates of serotonin synthesis in human brain. Proceedings of the National Academy of Sciences, 94(10), 5308–5313. https://doi.org/10.1073/pnas.94.10.5308
Ruigrok, A. N. V., Salimi-Khorshidi, G., Lai, M.-C., Baron-Cohen, S., Lombardo, M. V., Tait, R. J., & Suckling, J. (2014). A meta-analysis of sex differences in human brain structure. Neuroscience & Biobehavioral Reviews, 39, 34–50. https://doi.org/10.1016/j.neubiorev.2013.12.004
Unknown author(s). (n.d.). Geschwind–Galaburda hypothesis.
Waldman, K. (2019, March 2). The Gendered Brain by Gina Rippon – review. The Guardian. https://www.theguardian.com/books/2019/mar/02/the-gendered-brain-by-gina-rippon-review