On the Theory That Gender Difference Is Innate, Part 1

Part 2 will go live tomorrow — March 24th, 2015 — morning. 

old photo of boy and girl playing house

IT’S COMMON for people to attribute their interests and capacities to their gender, and it’s hard to dispute that, generally, men and women display different interests and capacities. The crucial question is: Are gender differences innate or learned? This is a hot topic of debate in the scientific community, particularly among neuroscientists, but the fact that there is such a question doesn’t seem to have entered mainstream public consciousness.

It should. There’s ample evidence that parents and teachers start treating boys and girls differently from an early age, based on the assumption that gender difference is inherent (check out these articles at education.com and Newsweek for just two of many examples). Are we playing to the strengths of each gender, or creating difference that ultimately limits possibilities?

The conclusion we come to as to whether gender difference is innate or learned has an impact on how we see ourselves and others — what we see as possible, what we choose to do, what we expect from others. This article examines the argument that gender difference is innate — both its theoretical underpinnings in evolutionary psychology and the behavioral and neuroscientific research that some claim support those underpinnings. Part II of this series will consider the theory that socialization, as opposed to biology, creates gender difference.

Evolutionary psychology states that our genes are programmed a certain way based on what was advantageous to human survival — dating back to the hunter-gatherer days. Women had the primary role of child-bearer and nurturer (in addition to managing household tasks and gathering food in low-risk situations) and men had the role of bringing home the meat, fending off predators, and protecting the family. It benefited human society for women to be nurturing, empathetic, and communicative and for men to be spatially intelligent, competitive, and aggressive. In fulfillment of their role, men faced complex problems that needed to be solved, leading to more complex problem-solving ability, whereas women gained advanced language skills and social abilities.

Proponents of the innateness of gender difference point to a surprising amount of research that supports this theory. The following is not an exhaustive list of relevant studies, but what I found to be the most-discussed and most significant in connection to this debate.

Much of the research in support of the innate essence of gender difference is neuroscientific; female and male brains have been found to be different in various studies. One significant study from 1986 found that the corpus callosum – the bundle of nerves that connects the two hemispheres of the brain – was larger in female fetuses when compared to their male counterparts as early on in gestation as 26 weeks, although researchers noted that the difference was not statistically significant.

Those results, however, received some bolstering when researchers conducting a study in 2013 found that, in the brains of people 14 years of age and older, females exhibit greater cross-hemisphere connectivity, whereas males exhibit greater front-to-back connectivity. The implications, according to some researchers, are that female brains are hardwired for emotional processing and language skills (which are thought to rely on interconnectivity of left and right brain areas), whereas male brains are hardwired for spatial and physical intelligence (involving more front-to-back connectivity).

Further differences can be found when considering the development of the brain in certain areas during early childhood as it occurs in both sexes. According to one study, the areas of the brain believed to facilitate mathematical and geometrical thinking develop four years earlier in boys (at the age of six) than in girls; on the other hand, the areas responsible for language skills develop six years earlier (at the age of six) in girls than in boys.

The final neuroscientific study I’ll note found that the male brain contains 6.5 times more grey matter (aka “thinking matter”) as female brains, whereas female brains contain nearly 10 times more white matter, which allows for connections between different areas of the brain. These results suggest that male brains are predisposed for intelligence in tasks involving more “localized processing,” such as math, and that women are predisposed for tasks that require greater interconnectivity, like language.

In order to address the question as to whether socialization could somehow be responsible for the above-noted differences, several researchers have studied newborn infant behavior. One oft-cited behavioral study from 2000 assessed 102 newborn infants’ behavior when presented with a picture of a face and a picture of a mobile. Overall, male infants showed more interest in the “physical-mechanical object” (they spent an average 51.9% of “looking time” focused on the mobile, compared to 40.6% for the females), whereas females on average paid more attention to the face (a mean 49.4% of “looking time” compared to 45.6% for males). The researchers concluded from this that females are naturally more social, since newborns are immune to the effects of socialization.

The theoretical underpinnings of evolutionary psychology make some sense; are we not, at the end of the day, animals that have evolved? Research has indicated that men’s and women’s brains have significant differences reflective of gender stereotypes, and newborns may show signs of dimorphism. There’s another side to the gender story, though. In Part 2, we’ll look at the arguments of several researchers who claim that, despite the suggestions of the above research, gender difference is largely, if not exclusively, attributable to socialization.

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