Females can carry higher levels of genetic defects without getting brain development disorders, research shows.
Are men inherently better than women are at some skills, and vice versa? Though we tend to think otherwise -- and there are always notable exceptions -- scientific research frequently concludes that men and women excel in different areas.
So what about nature versus nurture? As Diane Halpern, a professor of psychology at Claremont McKenna College, said during the British Psychological Society Annual Conference last year: "We do socialize our boys and girls differently, but the contribution of biology is not zero."
Men are better at judging person’s size based on their voice
A study in the latest Biology Letters holds that "men are better than women at acoustic size judgments." This means that men have an enhanced ability to determine a person's size based on the sound of his or her voice, according to Benjamin Charlton and colleagues from the University of Sussex. The findings, conclude the authors, "lend support to the idea that acoustic size normalization, a crucial prerequisite for speech perception, may have been sexually selected through male competition."
Men have better spatial awareness
Men possess a stronger ability to think of objects in three dimensions, helping with navigation, which was also discussed during the British Psychological Society Annual Conference. Even 3-month-old infants exhibit the sex-based behavioral difference. It could be that hunting, competitive battles and other activities conducted in the past helped to lock the skill into males.
Ingrid Taylar, Flickr
Women are better at locating specific items
Men often may have better spatial awareness than women do, but women are "better at remembering where things are," Halpern said. As a result, women are more likely to navigate using landmarks. While both men and women can therefore find their way to places with about equal skill, women might have an edge, since they could likely find things like missing car keys and maps first.
Maxwell GS, Wikimedia Commons
Women are better at worrying
Women produce only about half as much serotonin -- a neurotransmitter linked to depression -- as men do and they have fewer transporters to recycle it, according to Karolinska Institute research. As a result, women tend to worry more. That’s not always a bad thing, as women might then possess an enhanced ability to foresee problems and plan how to handle them.
Women detect colors better than men do
Women can detect subtle variations in color that men fail to identify, such as noting certain off-white colors versus white, Israel Abramov of CUNY’s Brooklyn College, determined a few months ago. It could be that women -- acting as gatherers -- developed improved color detection while searching for edibles. Abramov suspects that sex hormones are behind the differences, given that male sex hormones can alter development in the visual cortex.
Men handle lack of sleep better than women do
A Duke University study found that men could tolerate sleep deprivation more than women could. This is either good or bad news for men, as sleep is involved in brain repair, when the brain sorts out memories and other information acquired throughout the day.
We are evenly matched at multitasking
Some studies have found that men are better at multi-tasking, while others have determined just the opposite. When compiled, the data so far suggests that our multitasking skills could be evenly matched.
As we age, we also tend to lose, at about the same rate, our ability to handle more than one activity at once. Older men and women exhibit more difficulty in switching between tasks at the level of brain networks, according to a study published in Proceedings of the National Academy of Sciences.
Men are better at detecting infidelity
Men appear to be better at reading subtle vocal, visual, scent and other cues indicating their partner's fidelity, concludes a study published in the journal Human Nature. The downside, said co-author Paul Andrews of Virginia Commonwealth University, is that that these cues aren’t always accurate, and men are more likely than women to falsely suspect cheating.
Yet another study on cheating, published in the Journal of Marital and Family Therapy, found that men are more upset by sexual infidelity, and while women are more upset by emotional infidelity. Women, it should be mentioned, outperform men when identifying emotions, according to a study in the journal Neuropsychologia.
We are evenly matched in terms of intelligence
Men tend to be larger and, as a result, tend to have bigger brains. Size, however, does not necessarily correlate with intelligence. Braininess instead relies more on neuronal connections, which we help forge when learning by experience or study.
Historically, women's IQs have lagged behind those of men by up to 5 points, but now women are surpassing men in such tests. Rex Jung, an assistant professor of neurosurgery at the University of New Mexico, has found that men tend to have more brain grey matter while women have more white matter. The differences yet again are evident, but it appears that the evolutionary battle between the sexes can, at least for now, be judged as a tie.
Women usually live longer than men
Better immunity, reduced risk for blood diseases and lower risk-taking may give women an edge on longevity. Based on Centers for Disease Control data, women tend to have a life expectancy that’s 5.3 years greater than men's, but the gap is narrowing. In 1978, it was 7.8 years. The good news for men is that they tend to remain sexually active longer than women do. "Interest in sex, participation in sex and even the quality of sexual activity were higher for men than women, and this gender gap widened with age," said Stacy Tessler Lindau of the University of Chicago, who worked on a related study.
Women are able to carry higher levels of genetic defects without getting brain development disorders such as autism, supporting the possibility of a "female protective effect," finds a new study.
The study gives clues as to why 50 percent more males typically have an intellectual disability than females, and why boys are four times more likely to have autism than girls.
Professor Evan Eichler of the University of Washington, USA, led a Swiss-U.S. collaboration which published their results in The American Journal of Human Genetics today.
The team looked for genetic defects in 15,585 people who had been diagnosed with a range of disorders all thought to be due to faulty brain development -- known as neurodevelopmental disorders. Some of these people had autism spectrum disorders but they were not separated out from the rest.
The defects they were looking for were large "copy number variants" (CNVs) -- sections of chromosomes carrying perhaps a dozen genes which are either missing, or present as multiple copies.
Surprisingly, the females in the sample had more CNVs than the males. Although both sexes in the study had neurodevelopmental disorders, the females were carrying a bigger "burden" of genetic damage.
Eichler says this fits with females somehow being better protected from the effects of the CNVs. "It takes a lot more mutational hits to make a woman cross the threshold for a disorder," he said.
"The next question was... do you see this in autism?" said Eichler.
The team then focused on autism alone using a separate group of 762 families with autism spectrum disorders. The females in this group carried an even greater burden of CNVs.
These women were also more likely to carry tiny harmful mutations, affecting just a couple of base pairs in the DNA, than the men in the group.
Why are males more vulnerable?
Eichler now wants to do more research on thousands rather than hundreds of people with autism spectrum disorder, to validate and extend the results. He'd like to pinpoint the genes that most put people at risk of the disease.
As to why females are protected - he speculates that hormonal influences may be involved and adds "there is some data to suggest that we are hard-wired differently, but this is not my area of expertise."
And females are "genetically more robust because they have two X chromosomes while males are stuck with a single X and all the mutations...that are on it."
Commenting on the paper, Professor Cheryl Dissanayake, director of the Olga Tennison Autism Research Centre at La Trobe University, says she is not a geneticist but believes the paper sheds light on the question of why males are more affected than females.
"We've often speculated about a 'female protective factor' but never really understood why that might be."
"This is basically saying females need more genetic damage to have autism or a neurodevelopmental disorder than do the males -- it provides a clue."
The question that now needs to be answered, she agreed, is "what makes males more vulnerable to these genetic defects than females?"