We may never know every subtle difference, but gender research is coming a long way.
The researchers reason that the maternally-inherited X chromosome is epigenetically silenced, potentially through the addition of methyl groups. And this isn’t as far-fetched as it sounds. It’s called genomic imprinting, and it’s known to occur in a handful of mammals. Alleles from one parent (in this example, the mother) are silenced, while those from the other parents (here, the father) are expressed.
However, further investigations of this phenomenon, at least in terms of gender differences in social cognition, have been inconclusive. A more recent study did not find the same pattern of chromosomal inheritance and social cognition; in fact, some of the results were actually reversed from the previous study. While the original study has been replicated (but not published) by the original authors, the scientific community is still split on the controversial idea that genomic imprinting plays a role in the social cognition gender gap.
Studying another genetic abnormality called congenital adrenal hyperplasia, or CAH, has provided solid evidence that biology plays a role in shaping early behavioral differences between boys and girls. Generally, toy preferences in human children are attributed to cultural pressure and socialization; adults encourage girls to play with dolls and boys to play with trucks. But a group of researchers wondered whether sex-specific play behavior might also be influenced by hormones.
People with the classic form of CAH experience very high levels of masculinizing hormones called androgens in utero, thanks to an inability to produce certain enzymes. The authors hypothesized that if androgen exposure affects toy preferences, girls with CAH might prefer traditionally “male” toys over stereotypically “female” toys.
And they were right: 3- to 8-year old girls with CAH spent much more time playing with toys generally considered to be “boys’ toys”—including a helicopter, a fire engine, and Lincoln Logs—than with “girls’ toys” such as dolls and kitchen supplies. In fact, these girls spent just about as much time playing with these toys as boys did.
Although it’s possible that this is a product of the girls’ upbringing, other studies have found that parents of girls with CAH don’t encourage their daughters to play with opposite sex toys. In fact, they praise these girls more when they do play with “feminine” toys. Therefore, these results provide rather convincing evidence that hormone exposure may dictate toy preferences in girls with CAH and potentially in the rest of the population as well.
Studies in other species, such as rhesus and vervet monkeys suggest that other primates may share humans’ sex-specific toy preferences, lending even more weight to a biologically-based explanation.
The role of “nurture”
So, there is some evidence that biology plays a role in male-female behavioral differences via our genes and our hormones. But how influential is, well, everything else?
If the environment played no role in sex differences, gender gaps should be consistent across cultures. But this isn’t what researchers find; behavioral differences between men and women range widely—and sometimes disappear—in other countries. In Turkey, Korea, and Italy, the mathematics gender gap is large, and boys do much better than girls do on standardized math tests. In Iceland, there is also a large gender gap when it comes to math, but here, girls, not boys, score the best. In Norway and Sweden, there is almost no difference in the performance of boys and girls. These differences appear to be correlated with a general measure of gender inequality in each country, as calculated by the World Economic Forum. Countries where women are politically and economically empowered have the smallest sex differences, at least when it comes to math. However, these countries also have the largest gender gaps in reading, and here, girls actually outperform men. In both cases, it’s clear that a simple biological explanation doesn’t cut it. There is a definite relationship between sex differences in test performance and the cultural milieu of different nations.
Researchers found a similar phenomenon when they looked at spatial reasoning among members of two tribes in India. The tribes are closely related in terms of genetics but differ greatly in their social structures: the Karbi are patrilineal (inheritance passes from father to son, and most rights belong to men, not women), while the Khasi are matrilineal (inheritance passes from mother to daughter, and women are more empowered than men). Among the patrilineal Karbi, men were much better at a spatial rotation task than women. However, when it came to the matrilineal Khasi, women outperformed men on the puzzle. (See Ars’ previous coverage on this study for more information.)
Many studies also find that situational factors play a large role in whether or not men and women demonstrate measurable differences in behavior. Simply asking for a participant’s gender can cause differences in performance; women tend to do better on verbal tests and worse on math tests after being asked their gender. By making people think about their gender (increasing its “salience,” in psychology parlance), researchers believe that they are triggering a tendency to conform to traditional gender stereotypes.
Note, however, that none of the studies advocating the role that culture and environment play in gender gaps actually rule out an evolutionary or biological contribution. As un-PC as it may be, it’s nearly impossible to believe that over our evolutionary history, the brains and behavior of men and women have not succumbed to different selective pressures. In the natural world, species from hummingbirds to hyenas demonstrate remarkable differences in the behavior of each sex. Is it so hard to believe that men and women have evolved to behave differently from one another?
However, the truth probably lies somewhere in the middle; our evolutionary history may have selected for differences in the behavior of males and females, but they aren’t of the “Mars-Venus” magnitude that pop culture would like us to believe. Furthermore, the influence of the environment on our behavior is so strong that “nurture” likely plays a much larger role in gender gaps than “nature.” It may seem disconcerting that culture can increase—or even spontaneously create—sex-specific differences in our behavior, but this also suggests that we can affect, and perhaps even eliminate, some gender gaps if we see fit.
Shifting gaps
And today, gender gaps are changing. Some gaps are narrowing, others are widening, and still others have reversed. For instance, in 1970, just 42 percent of undergraduates were women; today, women make up 57 percent of the student body at colleges and universities. That number is predicted to grow to 59 percent by 2020. Census data shows that the number of men that have left the workforce to become stay-at-home dads has more than doubled since the early 2000’s. Even our perceptions of gender gaps are changing: earlier this year, the US military lifted the ban on women in combat.
Thanks to an improving body of knowledge about gender gaps, we are starting to understand how and when some sex differences are manifested. And, in turn, scientists, psychologists, and educators are now beginning to figure out how we can manipulate these gaps to affect sex-specific behavior.
For instance, one study suggests that choosing specific test administrators can increase or decrease a gender gap; girls did just as well as boys on a challenging math test when a “female role model” (in other words, a woman that’s good at math) administered the test, but they performed much worse than boys did with a male administrator. Other studies, too, suggest that female role models are an effective way to promote self-confidence in girls when it comes to math and science.
Recent research also suggests that boys and girls respond very differently to repeated contests, compared to single stand-alone competitions. In a “one-shot” math contest, where kids are tested just a single time, elementary school-age boys tend to outperform their female classmates by about 10 percent. However, in a sequential competition where kids are quizzed over multiple rounds, the sex difference disappears. Ironically, however, this actually raises the possibility of another gender gap, since the researchers believe their results may stem from the different way males and females respond to competition.
By taking these findings into account, researchers may be able to get a more accurate picture of males’ and females’ abilities, and these concepts could potentially be used to help each gender perform their best on tests, in schools, and in the workforce. The end goal isn’t to create a homogeneous society where everyone performs equally, but it's instead to make sure that our preconceptions about gender-specific behavior aren’t actually magnifying or creating differences in how males and females behave.
We’re still far from understanding where gender gaps come from, or even whether there really are concrete cognitive or behavioral differences between men and women in some areas. In all likelihood, we will never understand the full range of subtleties involved. In fact, research on sex differences in humans seems to be raising just as many questions as answers. But forward-thinking scientists and clever, well-designed studies are helping us move in the right direction: away from an oversimplified and exaggerated Mars-Venus dichotomy and toward a more thorough understanding of the complex underpinnings of gender gaps.
Courtesy: arstechnica
Courtesy: arstechnica
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