Does How You Look Determine Your Personality?

This week in science: the difference between men and women's brains as they get older, how your appearance influences your personality, and how birth control could affect the way women read facial expressions.

Feb 15 2019, 4:28pm

Nicola Powys / Unsplash

Each week, we read what's going on the world of science and bring three of the wildest findings straight to you. Here's the latest:

Do our looks determine our personalities? Maybe, but not in the ways you think.

There’s a technical-sounding theory, called facultative calibration, that you’re familiar with even if you’ve never heard its name. It argues that the way you look physically influences your personality and behavior, because your physical appearance provides advantages (or disadvantages) in social interactions. Advantages, for instance, could lead to being extraverted or aggressive.

Examples of this resemble tropes or stereotypes that already exist, says Christoph von Borell, a psychologist at the University of Goettingen in Germany: that stronger men and physically attractive women are more angry, aggressive, and more extraverted, or outgoing, assertive, and active.

But in a new study in Evolution and Human Behavior, Borell and his colleagues tried to prove that these associations with physical attractiveness were true, and couldn’t confirm many of them, especially in women—they didn’t find a connection between attractiveness and extraversion in women. (In the study, they let the subjects rate their own attractiveness level, as well as getting an outsider’s rating.)

“It seems that judgments of physical attractiveness do not lead to a behavioral adaptation in women, perhaps (and hopefully) because other aspects of women, say, how intelligent or witty they are, play an important role, too,” Borell tells me.

They did find some associations between being more active and assertive and stronger and more muscular men; strength being a different trait than attractiveness level. Some of the other associations I found intriguing were an association with height and gregariousness in men, and lung function and excitement-seeking in women. So there seems to be some evidence of a facultative calibration, but it could be more complicated than originally envisioned.

“[It] could be that there are also possible strategies counter to the expected association between appearance and behavior,” Borell says. “For example, that people who are not valued for their looks compensate with being especially outgoing. For men the association between appearance and behavior could be wired more directly, since being strong or muscular could be thought of as prerequisite for being active, assertive, or physically aggressive.”

Birth control might change women’s ability to recognize complex emotions

So many women are on birth control, and yet we’re still learning about the subtle side effects taking hormones has on women’s minds and bodies. A couple weeks ago, I wrote about research that found that hormonal birth control could change which partner a woman was attracted to.

Now, a new study in Frontiers in Neuroscience found that birth control could be affecting the way women perceive facial expressions in other people. The study found that women taking an oral contraceptive pill were almost 10 percent worse at interpreting subtle emotional expressions like pride or contempt compared with those who weren’t on the pill.

Variation in amounts of hormones like estrogen and progesterone can already affect emotion-recognition abilities, possibly by changing the way neurons behave in brain regions that are implicated in emotion processing, says senior author Alexander Lischke, a psychology researcher at the University of Greifswald in Germany. So if hormonal birth control suppresses or changes the cycle of these hormones, it could have an effect on those processes too.

Lischke and his colleagues gave their subjects an emotion-recognition task called Reading the Mind’s Eye. (You can take a version of it here.) The test asks you to identify complex emotional expressions from subtle cues from the eyes, and only the eyes—the rest of the face is blocked off.

“The expressions did not depict basic emotions like fear or anger but rather complex ones like, for example, pride or contempt,” Lischke tells me. “As a consequence, the emotion-recognition task was quite challenging.”

The study found that 42 women on birth control, as they hypothesized, were less accurate in recognizing emotions when compared to the 53 women not on birth control, “in particular during the processing of expressions that were difficult to recognize,” the paper says.

Misreading someone’s expressions can lead to misunderstandings and conflicts in professional or personal relationships—you can imagine that misreading pride for contempt might lead to problems. Women should potentially be made aware of these side effects, Lischke says, but more work needs to be done to find out how much they could influence everyday life, since the effects do seem to be quite subtle.

“Further studies are needed that replicate and extend the findings of the present study before we should start worrying about the side-effects of oral contraceptives on women’s emotion-recognition abilities,” Lischke says. “We should not forget that oral contraceptives have far more positive effects than negative effect.”

Women’s brains appear to be three years younger than men’s

As we get older, our brains literally shrink in size, and their metabolisms slow down. But this aging process isn’t uniform—some people’s brains might decline more slowly, and possibly be associated with less dementia or cognitive issues.

Why do some people have a rapidly declining brain and others don’t? Scientists are still trying to determine why, but one reason might be gender. A new study in Proceedings of the National Academy of Sciences found that women’s brains seemed to be about three years younger than men’s of the same age. It could be “one clue to why women tend to stay mentally sharp longer than men,” a press release says.

It’s not the first time it’s been pointed out that men and women’s brains could be affected by age in different ways. A previous study from 2015 found that in some parts of the brain, middle-aged women had more grey matter than middle-aged men did. Brain differences could start as early as puberty, where sex differences could influence brain development and blood flow to the brain, “raising the possibility that the adult female brain retains more youthful…features compared with the adult male brain,” the study says.

Manu Goyal, an assistant professor of radiology at the Washington University School of Medicine in St. Louis and first author on the new work, tells me that they measured brain metabolism and blood flow in 121 women and 84 men from 20 to 82 years old. Specifically, they looked at how much glucose (or sugar), oxygen and blood flow the brain was using in its different parts. When we age, these factors typically change, and the researchers used them to calculate a “metabolic brain age.”

Using algorithms that were trained to find a relationship between age and brain metabolism, they found that the brains of the women were about three years younger than their chronological ages. They observed this even in the female subjects who were in their 20s. He tells me it might be due to those differences in development, or it might be some other small but important variations in the cells that make up female and male brains. It could be that hormones play a role.

"It's not that men's brains age faster [but rather that] they start adulthood about three years older than women, and that persists throughout life," Goyal says in the release. "What we don't know is what it means. I think this could mean that the reason women don't experience as much cognitive decline in later years is because their brains are effectively younger, and we're currently working on a study to confirm that."

Your weekly health and science reads

A Ketamine-Based Nasal Spray for Depression Could Soon be Approved by the FDA. By Ed Cara in Gizmodo.
It looks like it’s going to happen: Ketamine has been an off-label use for depression so far. But a panel of experts voted that the benefits of approving this new drug outweighed the risk.

The Women Who Contributed to Science but Were Buried in Footnotes. By Ed Yong in The Atlantic.
“They became literal footnotes in scientific history, despite helping make that history.”

More than 26 million people have taken an at-home ancestry test. By Antonio Regalado in MIT Tech Review.
That is… a lot of people. “If the pace continues, the gene troves could hold data on the genetic makeup of more than 100 million people within 24 months,” Regalado writes.

Big Bang May Have Created a Mirror Universe Where Time Runs Backwards. By Tim de Chant in Nova.
It’s always fun to read something that I barely understand, and this piece on the forward motion of time fits the bill.

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