Research suggests that male and female brains are wired differently since biological sex shapes them

The results of a study published in February 2024 by a team of researchers at Stanford University have shed new light on the controversial subject of whether men and women have different brains.

According to the authors of the study, AI-generated brain scans do indeed indicate that males and females are wired differently, and that contrasts in cognitive ability do exist. But the wider scientific community is divided on the issue, with some academics warning of the propagation of a “hunt the sex differences” agenda.

So, is searching for a ‘male’ and ‘female’ brain a worthwhile pursuit, or just a waste of time? Questions about whether or not men and women are wired differently have raged for centuries. But do men and women really have different brains?

Neurosexism

Actually, is there such a thing as neuro-sexism, and is the search for male and female distinctions inside the skull worth the effort? Well, it depends on who you talk to.

According to a 2021 study published by the National Center for Biotechnology  Information (NCBI), on average, men and women differ in brain structure and behavior, raising the possibility of a link between sex differences in brain and conduct.

The study, however, found only a weak association between brain size and behavioral differences.

Furthermore, the basis of average differences in male and female behavior for example, specific cognitive abilities and personality traits, is not well understood and remains open to interpretation.

But the question remains: is the brain gendered?

A paper published on February 2024 by a research group from Stanford University suggests that it is. The research group used an artificial intelligence (AI) neural network model to look at brain scans to see if it could reliably and robustly tell female and male brains apart.

The aim was whether the algorithm can tell if the brain patterns being looked at were from women or men. The answer was that it could. Brain scans showed that there are differences in regions responsible for certain functions.

Most of these differences are in the default mode network (the part of the brain in which we store key elements of social knowledge acquired by interaction), and the striatum and limbic network areas involved in a wide range of processes including daydreaming, remembering the past, planning for the future, making decisions, and smelling.

Findings made public

The findings were published by the Proceedings of the National Academy of Sciences (PNAS) and carried by various media outlets.

According to the team at Stanford, these results have effectively added a new piece to the puzzle. They believe their research adds weight to the theory that biological sex shapes the brain. But not everyone’s convinced.

Searching for a ‘male’ and ‘female’ brain is nothing new. But it’s a controversial subject that has its detractors.

The scientific journal Nature reminds that the history of sex-difference research is rife with innumeracy, misinterpretation, publication bias, weak statistical power, inadequate controls, and worse.

Indeed, neuro-sexism has endured since the 19th century. Then, scientists and philosophers quickly drew conclusions about the mental inferiority of women, or their lack of aptitude for certain tasks, on the basis of alleged anatomical differences between male and female brains. Pictured in 1931 is a woman seated with a psychograph, or phrenology machine, on her head. The psychograph claimed to mechanically discern a subject’s aptitudes in a number of mental faculties.

However, early research into measurements of skull capacity demonstrated that the brains of men were, on average, somewhat bigger and heavier than those of women. On this basis, some commentators advanced the so-called ‘missing five ounces’ theory, which they believed was key to men’s supposedly superior abilities.

Bigger body, bigger brain

In fact, notes New Scientist, the simple explanation is that bigger bodies require more brain tissue to run them, a relationship seen across animal species.

While not wanting to draw any inferences about the value, or even the meaning, of the differences the Stanford team found, neuroscientist Gina Rippon, writing in The Guardian, warned of propagating a ‘hunt the sex differences’ agenda.

“There seems to be an implacable need, even in today’s world, to find a nice set of biologically programmed, sex-specific differences in the brain, and agree that these must be the basis of any female-male differences in behavior, or temperament, or ability and achievement,” argued Rippon, who is emeritus professor of cognitive neuroimaging at the Aston Brain Centre at Aston University in England.

Researchers at Stanford, meanwhile, expressed optimism that their work would help shed light on brain conditions that affect men and women differently. They cited the fact that autism and Parkinson’s are more common in men, whereas multiple sclerosis and depression are more common in women.

Motivation behind the study

Commenting further, the study’s senior author Vinod Menon, professor of psychiatry and behavioral sciences at Stanford, said in a statement: “A key motivation for this study is that sex plays a crucial role in human brain development, in aging, and in the manifestation of psychiatric and neurological disorders.”

“Identifying consistent and replicable sex differences in the healthy adult brain is a critical step toward a deeper understanding of sex-specific vulnerabilities in psychiatric and neurological disorders,” added Menon.

Still, the notion that there are cognitive differences between men and women based on brain size remains a contentious one.

But with gender issues now one of the most talked about subjects of the 21st century, the question of whether there are differences between the brains of men and women has been placed further under the microscope.

Equal but different?

“If we continue to buy in to the argument that differences between men and women are hardwired, permanent and intractable, then any attempts to address inequalities will all too easily be dismissed,” underlined Rippon.

But Stanford’s Vinod Menon warns that “overlooking sex differences in brain organization could lead us to miss key factors underlying neuropsychiatric disorders.”

So while AI-led research is cutting through historical discrimination and gender politics to get to the truth about differences between the brains of men and women, the attitude adopted by many scientists is that any results need to be interpreted cautiously.

Sources: (NCBI) (PNAS) (The Guardian) (Nature) (New Scientist) (Stanford Medical Magazine)