What’s the connection between your facial appearance and your personality/character? Sometimes you can judge a book by its cover. Check out “What’s in a Face?, my cover article in the December 2012 issue of Psychology Today.
Not long ago, a group of Czech biologists embarked on an interesting experiment.Their inspiration was the enormous body of evidence that finds that human sweat carries information about a person’s gender, genetic compatibility, and reproductive state. We breathe in other people’s body odors, and, on a subconscious level, find them attractive, passable, or repulsive. This is the sexual selection theory behind body odors. We sniff out the best mates.
There’s even more going on under our noses, the researchers thought. From an evolutionary standpoint, we also ought to care about a mate’s nutritional status. After all, a good diet is an indicator of one’s overall condition — which is related to fertility and stamina. In the animal world, there’s plenty of evidence that eating healthily leads to more sex. Among meadow voles, both males and females prefer the odors of those that eat high-protein diets. Animals that haven’t eaten in a day produce less attractive smells than sated ones.
So, what would happen if you ate a lot of a strong-smelling healthy food? Garlic, say.
The researchers asked a group of subjects to eat bread laced with garlic cream cheese (the equivalent of 2-4 cloves) every day for one week. The next week, they ate their bread with plain cream cheese. At the end of the experiment, female raters were brought in to smell the pads that each man had worn in their armpits. Sniffing time was not restricted.
Which armpit pads were rated as more attractive-smelling — the garlic ones or the plain ones?
Garlic, of course. And here’s the shocker:
The odour of donors in the experimental (garlic) condition was judged as significantly more attractive, more pleasant and less intense than in the control (non-garlic) condition . These preliminary results unexpectedly suggest that garlic consumption positively influences body odour.
Several explanations are offered. Garlic influences body odor with antioxidants, which protect against bad-smelling metabolites, indirectly resulting in a healthier-smelling personal odor. Or, garlic’s bactericidal properties reduce the intensity of bad-smelling armpit odor. Either way, you’re advertising a healthy metabolism, and healthy smells better.
Have we evolved to be attracted to body odors from healthy food? The researchers weigh in:
It is thus plausible that human odour preferences were shaped by sexual selection to be sensitive to odour cues of current metabolic functioning in potential mates. These cues are affected by the amount and quality of food such as garlic digested by the producer.
The study warrants more research on other foods. But it supports the theory that what you eat makes you smell better — which whets others’ appetite for you.
*If you like this blog, click here for previous posts or follow me on Twitter. If you wish, check out my new book on what we don’t expect when we’re expecting: Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy.
Check out my feature article, Slips of the Tongue, in this month’s Psychology Today.
Check out my video and excerpt from Chocolate Lovers on Big Think.
Not long ago, a single friend of mine observed something about the photos that men post of themselves on Match.com and other online dating sites. Many—too many for her taste—also include women. Ex-girlfriends, presumably, with their slender arms thrown around the men in question. Or possibly friends, but always attractive ones. Even when the woman in the photo had been cropped out, whatever boady part remained in the frame was comely. Long blond hair. Manicured nails.
Why do so many singles post pictures of themselves with exes? Do they know, at least on a subconscious level, that having a gorgeous ex makes them look hotter?
It actually does, according to a matchmaking strategy called mate-choice copying. Birds do it, and so do many other animals. There’s mounting evidence that humans are no exception. If a person has an attractive partner, then there must be something worthwhile about him or her that may not meet the eye. It’s a wisdom-of-crowds approach.
In a recent mate-copying study, researchers at Duke University and the University of California at Davis asked a group of straight volunteers to rate the attractiveness of men and women who were photographed solo. A second group of volunteers was asked to rate the attractiveness of the same men and women when paired with a person of the opposite sex. They were told that each couple had once been romantically involved but had broken up. How hot was the individual of the opposite sex? How much would they like to date that person?
Turns out, it depends on the ex.
Both male and female volunteers rated faces as more attractive, desirable, and dateable when paired with hot exes than when featured solo.
While having a hot ex is a boost to your attractiveness, having a homely one can hurt you. When volunteers spent more time looking at a potential mate’s unattractive partner, they were less interested in dating that person.Take note: volunteers were only asked to rate people of the opposite sex, but they all spent significant time looking at each person’s partner.
There’s an exception to this rule, and (as usual) it’s hot women. While female volunteers downgraded otherwise hot men if they were paired with a dumpy partner, men gave high ratings to an attractive woman regardless of her partner’s appearance. Women, generally the choosier and more cautious sex, are more likely than men to rely on social cues such as whether other women find the target guy attractive.
Is it really a good strategy to include a picture of yourself with an attractive ex-girlfriend or boyfriend (or a hot friend) in your dating profile? My exasperated friend would say no, yet all too often the guys that she finds exceptional are the ones who have hot exes.
This is not an ad in the personals. It’s the opening line of the commentary in the straitlaced scientific journal, Proceedings of the National Academy of Sciences (PSAS). The authors, neuroscientists Liisa Galea and Cindy Barhain, intend to shock. Why, one wonders, would a man have no luck in love?
Findings from a new study suggest it may be your mother’s dietary exposure to bisphenol A (BPA).
Galea and Barha have all my attention now. Ever since my pregnancy, I have been tracking studies on BPA’s subtle yet shocking effects. One of the most common chemicals in the world, bisphenol A is found in the stuff we use every day of our lives. Soup and soda cans. Water pipes. Computers. Cell phones. Thermal paper receipts. Paper money. Even some baby bottles—at least in the U.S., because they are not banned here.
Much of the trouble with BPA lies in its ability to fool estrogen receptors into thinking it’s estrogen. Imagine a man doesn’t know that the woman he’s marrying is really an alien in drag, and you have a sense of the danger here. BPA disrupts any process that estrogen normally mediates, affecting brain, body, and behavior. It also tinkers with the way genes express themselves, turning up those that would otherwise be turned off or down. BPA exposure has been linked to breast cancer, heart disease, obesity, diabetes, attention-deficit disorder, increased anxiety, a decreased IQ in children and a low sperm count in men.
Pregnant women and new moms should be especially cautious. BPA has been found in umbilical cord blood and in breast milk. It crosses the placenta and flows in fetuses. Young bodies are especially vulnerable to pseudoestrogens. The toxin strikes us moms, too. Researchers worry that BPA may affect women’s brains in a way that alter their maternal instincts. In laboratory studies, BPA-exposed female rats are less likely to nurture their offspring—they lick them less—which in turn affects the emotional and cognitive system of their babies. They become more fearful and anxious.
And now, there’s more.
There is evidence that BPA emasculates males and makes them sexually undesirable. Galea and Barha’s opening lines in PSAS are tongue in cheek—they are describing a new study at the University of Missouri on the effects of BPA on deer mice—but the application to humans is implicit. Adult mice whose mothers were fed a dosage of BPA equivalent to what the USDA deems safe for pregnant women, were, well, different from other males.
“One of the prominent effects of early BPA exposure is that it eliminates a number of sex differences in brain and behavior,” the researchers wrote. It turned out that BPA-exposed males have impaired spatial ability (can’t find their way out of a maze or to their nest, considered unattractive to females). They also suffer from decreased exploratory ability (incurious and easily lost), and overall reduced attractiveness to the opposite sex. They may even smell different from their peers—in rodents, a sign of unhealthiness. Females are disgusted.
It’s not absurd to worry about similar effects of BPA-exposure on our babies. Men are not mice, but there is increasing evidence that BPA affects us as well, and in doses below the below the 50 µg/kg/day safety threshold in the United States. Almost every American pregnant woman (93 percent) has detectable BPA in her body, which is passed on to her fetus. The average BPA body burden of an American is high, alarmingly high, compared to other countries. We love our BPA-enriched Cokes and canned Campbell’s soups.
On a population level, how might BPA affect us? Might boys in the U.S. grow up to have poorer spatial skills—and, because it’s linked, weaker mathematical ability? Might they have little interest in exploring the world, preferring to hang out at home? Might our national temperament become more placid? Because BPA is lined with obesity and heart disease, will we become fatter and more sedate? And what about our sex lives?
Take a look at human history through the lens of hormones, as Harvard University’s Daniel Lord Smail did in his fascinating book, On Deep History and the Brain. Smail introduces a new view in which physiology and culture evolve symbiotically in a process driven by brain chemistry. Caffeine stimulated the body and mind, driving the industrial revolution and the modern corporation. Tobacco help us to focus and be calm. These substances changed the character of society. Now we have environmental toxins such as BPA (and other hormone disruptors such as phthlates and PCBs) that may also change our culture in subtle but very real ways.
BPA: Bad for your manhood. Bad for your sex life. Sensationalistic, sure—but would this get CEOs to pay attention? Hit them where it hurts.
Stubborn pushback—that’s the response from many corporations regarding BPA bans. The chemical is a mainstay in packaging, and to ditch it is disruptive for business. Coca Cola has famously refused to find an alternative. You can find BPA-free cans of beans from brands such as Eden, but not crushed tomatoes yet (in the meantime, buy them in glass jars). Avoid plastics that are marked with recycle codes 3 or 7; they may contain BPA. While Canada, Europe, and even China have banned the use of the chemical in baby bottles, the U.S. has not (although consumer demand has pushed many manufactuers to go BPA-free).
The good news, as I describe in my book, is that there is laboratory evidence that a diet high in folic acid and B12 may reverse at least some of the nasty effects of prenatal BPA exposure. How? One way that BPA tinkers with our systems is by attaching itself to strands of DNA and “turning on” certain genes (removing methyl groups) that are normally turned off—resulting in obesity, cancer, and other nasty effects. This is classic epigenetics—an environmental trigger affects the way that genes behave. Nutrients in green vegetables, beans, eggs, and soy may be protective (in those of us who include enough in our diet) because they turn off genes that BPA otherwise turns on.
Of course, the best protection is to turn corporations off BPA. That would really be a turn-on for us moms.
*If you like this blog, click here for previous posts. If you wish, check out my new book, Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy.