Science of Love, Sex, and Babies

Who’s Turned On By Pregnant Women?

Posted in parenting, pregnancy, psychology, science, sex by jenapincott on September 26, 2011

 

Early one evening late in my second trimester of pregnancy, I was standing in the dairy aisle of the grocery store, with one hand on my back and the other over the kicking baby in my distended belly. A young man approached me, initiated a conversation about the World Cup, and, casually, asked me if I’d like watch the game with him that weekend. “You’re pretty!” he whispered. I was shocked.

I wasn’t putting out a sexy vibe. (Not at all.) I had assumed that any male attention I receive in late pregnancy, including that from my husband, would be friendly, not sexual. Why would a man who is not the expectant father think pregnancy is sexy? But then other women told me similar stories about how they got hit on in third trimester. So I decided to look into it, and it turns out that a study on sexual attraction to pregnancy has recently come out.

A team of Swedish and Italian doctors, led by Emmanuele Jannini and Magnus Enquist, recruited nearly 2,200 men who had joined online fetish groups such as alt.sex.fetish and alt.sex.fetish.breastmilk. They presented a questionnaire that asked the respondents questions about their preferences for pregnant and lactating women. The survey also asked for the sex and age of each sibling, and whether the sibling is a full sibling or not (half-sibling or adopted child). Most respondents reported both a pregnancy and a lactation preference. The average age at which respondents became aware of their preference was about 18 years.

What Jannini and Enquist and their colleagues were searching for was evidence that there was something special about the upbringing of men that are secually aroused by pregnancy. They knew that a specific stimulus early in life can elicit sexual behavior when theat animal reaches sexual maturity. For instance, goats that are raised by sheep are sexually aaroused by sheep only. This is called sexual imprinting.

Is it possible that boys that are raised by women who are pregnant for much of their childhoods are unusually attracted to pregnant women?

It turns out, what’s good for the goat is good for the guy. The more exposed a man was to his mother being pregnant and breastfeeding when he was between 1.5 and 5 years old, the more likely he is, as an adult, to be sexually attracted to pregnant and breastfeeding women.

A younger sibling is the key to early exposure. The respondents who eroticized pregnancy and breastfeeding had significantly more younger siblings than expected by chance. Respondents with one sibling were older than their sister or brother in 66 percent of cases. Interstingly, siblings born of a different mother does not appear to be related to respondents’ sexual preferences. Only a boy’s own pregnant mother seemed to leave a sexual imprint.

Freud’s “oedipal phase,” from about 3 to about 5-6 years of age, only overlaps partially with the sensitive period suggested by this study’s data, the researchers are careful to point out. Sexual imprinting is different in that it’s motivated not by sexual drive but because the individual learns what’s normal during a sensitive phase of development and later seeks sexual partners that resemble his (or her) own parents.

What does this mean for women who are pregnant or plan to be pregnant? It means you may be able to predict how attracted your partner will be to you in late pregnancy. Does he have sibling born within five years after him? If so, he’s likelier to be turned on by your pregnant self.

As for the guy I met in the dairy aisle, I’d wager he had a younger brother or sister. I’d bet more on getting this right than the winner of the next World Cup.

 *If you like this blog, click here for previous posts and here to read a description of my most recent book, Do Gentlemen Really Prefer Blondes?, on the science behind love, sex, and attraction. If you wish, check out my forthcoming book, available October 11,  Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy. 

 

 

 

Assorted Trifles (from the science of love, sex, and babies)

Posted in news, parenting, pregnancy, psychology, science, sex by jenapincott on August 4, 2011

Research is like a box of chocolates; you never know what you’re going to find. An assortment of studies on love, sex, and babies — fresh from the lab.

Scientists found that men whose ring fingers are longer than their index fingers are likelier to have longer-than-average penises, at least among Korean men whose flaccid genitals were stretched under anesthesia. Studying the files of women who were raped in 1999-2006, French researchers discovered that there were fewer incidences of living sperm than in rape victims in previous generations, which supports the theory that sperm quality is declining. Women are likelier to get pregnant if they ovulate from their right-side ovary, visible by ultrasound, especially after two consecutive left-side cycles, inspiring women undergoing fertility treatment to desire a L-L-R pattern. Among women whose fetuses inexplicably died in third trimester, 64 percent (392/614) had a premonition before their doctors told them. They described a feeling of discomfort, of a strange unease; that they understood subconsciously that the baby would die. Many described how they dreamed of dead relatives and of death on the night the baby probably died. A recent fMRI study reported that women who had given birth vaginally exhibited greater activation in brain regions involved in the regulation of empathy, arousal, motivation and reward circuits in response to their baby’s cries compared to those who had not. Women who snore loudly and frequently were at high risk for low birth weight (relative risk = 2.6 [95% confidence interval = 1.2-5.4]), and fetal-growth-restricted neonates. The success of an IVF transfer may in part be predicted by how much glucose medium an embryo “eats” on days 4 and 5. On Day 4, female embryos consume significantly more sugar than males.

WAAROM VROUWEN CHOCOLA LEKKERDER VINDEN DAN SEKS

Posted in psychology, science, sex by jenapincott on July 4, 2011

The new Dutch mass market edition of Blondes (retitled, in loose translation, “Why Women Prefer Chocolate to Sex”)

The Real Purpose of Eyebrows?

Posted in psychology, science by jenapincott on July 4, 2011

Human faces are relatively flat. Alas, evolution has flattened the jutting jaw and the bulging brow ridge. 

Fortunately, we still have one reliable landmark:  the eyebrow.

According to a study by MIT behavioral neuroscientist Javid Sadr and his colleagues, eyebrows have remained because they are crucial to facial identification. Faces without eyebrows are like land without landmarks.

The study:  Volunteers were asked to identify fifty famous faces, including that of former U.S. president Richard Nixon and actor Winona Ryder.  The photos were digitally altered and displayed either without eyebrows or without eyes. When celebrities lacked eyes, subjects could recognize them nearly 60 percent of the time.  However, when celebrities lacked eyebrows, subjects recognized them only 46 percent of time.

The lesson:  eyebrows are crucial to facial identity — they’re at least as important as your eyes, if not more so.  If you put colored contacts in your eyes, pumped collagen into your lips, or put on a pair of funky sunglasses, people would probably still recognize you easily.  But try shaving off your eyebrows. Chances are that everyone will say they didn’t recognize you at first glance.

As Sadr points out, eyebrows pop out against the backdrop of your face — and for that reason not only identify who you are but how you’re feeling. Along with the lips, they may in fact be the most expressive part of your body. The single raised eyebrow is a universal sign of skepticism, and the dual raised eyebrow a sign of surprise.

The shape of your eyebrows also reveals, in a glance, a lot about your age and other characteristics.  Bushy, gnarly, salt-and-pepper brows:  older apha males. Thin, graceful arcs:  young, stylish women.  Sparse, light brows:  youths.  Waxed and tweezed, the brow can advertise good grooming.

Eyebrows sometimes meet each other halfway across the bridge of the nose, especially on men, to form a monobrow, which resembles the vanished browridge of our primate ancestors.  Distinctive? Yes, and also brow-raising.

 *This entry was previously published on this blog. If you wish, also check out my forthcoming book, Do Chocolate Lovers Have Sweeter Babies: The Surprising Science of Pregnancy. 

Are Extroverts That Way Because of Their Fathers?

Posted in parenting, psychology, science by jenapincott on June 24, 2011

All babies demand their parents’ attention. But how many 11-month-olds demand the attention of strangers, too? Ours does. We bring her to restaurants and she scans the room until she catches someone’s eye. My husband will pick her up and carry her over to her admirer, whom he’ll chat up. Dad’s a socialite, Baby’s a socialite. Mom reaches into her bag and pulls out a book.

You might think your baby’s social confidence depends on the usual mix of genes and environment. This is true, but it might not be the whole truth. There’s also evidence that children rely more on their father’s social signals than their mother’s. That is, socially confident dads may have more socially confident kids. Socially anxious fathers may have more socially anxious kids. It matters less whether Mom is a social butterfly or a bookworm.

The bulk of the research on paternal influence on sociability comes from Susan Bogels, a professor in Developmental Psychopathology at the University of Amsterdam, and her colleague Enrico Perotti. In a recent review, Bogels and Perotti draw on research that suggests a dominant paternal role in their children’s sociability, including:

In one study, 9-11-year-olds were asked to imagine themselves in a series of stories involving strangers, while their mother and father responded in a socially anxious or socially confident way. Children who had socially anxiety were more influenced by their father’s reaction more than their mother’s.

A study of boys with behavioral problems, including social anxiety, found that fathering, but not mothering, predicted the children’s level of inhibition. In another study, secure infant-father attachment, but not infant-mother attachment, predicted stranger sociability among toddlers.

• Among kids enrolled in treatment for social anxiety, those whose fathers had high levels of social anxiety had a worse outcome (were more socially anxious) than those whose mothers had it. Socially anxious mothers are not as likely as socially anxious fathers to make their kids less sociable.

So here’s the mystery: Why would fathers, who have less to do with childrearing than mothers, have more influence on their children’s sociabilty?

It’s an interesting question, and Bogels and Perotti have an interesting answer. “In the course of human history,” they write, “fathers specialized in external protection (e.g. confronting the external world outside the clan or extended family), while mothers provided internal protection (e.g. providing comfort and food). Therefore, children may be hardwired to respond more to their father’s signals about the social world than the mother’s, and adjust their behavior accordingly.

Through the ages, it benefited children to rely more on their father’s than mother’s cues about whether unfamiliar people are generally hostile or cooperative. Of course, gender roles have long since changed – moms go out into the world every day and meet strangers – but our instincts haven’t.

So the lesson here is that fathers orient their children outward, mothers inward. When researchers observed a group of toddlers taking swimming lessons, they took note of where the parents stood. Mothers protectively stood in front of their babies, encouraging face-to-face interaction with them. Fathers stood in back, so that their children would face their social environment.

∞∞∞∞∞∞∞∞∞∞∞∞

Bogel and Perotti’s review includes a fascinating aside about paternal roughhousing and its effect on children’s social confidence. Rough-and-tumble play – I think of my husband tossing our infant in the air, spinning her around, throwing her over his shoulder, as she giggles and squeals- gets a scientific seal of approval.

Here’s why. Kids learn to associate physiological arousal – a racing heart, tight chest, spinning head – with fun instead of fear, which crosses over into other social interaction. Roughhousing also involves behavior – being aggressive, sneaky, teasing, playful – that requires different roles and different responses, and forms a basis for social skills. By pinning kids to the ground, swinging them like sacks of potatoes, attacking them and getting attacked – fathers make their progeny more confident.

∞∞∞∞∞∞∞∞∞∞

So many questions. If we have evolved so that fathers strongly influence their children’s sociability, what does this mean?

It means that fathers who are socially anxious themselves are likelier to have kids who are not socially confident. If a kid suffers from severe social anxiety, perhaps his or her father should be involved in the kid’s therapy or get therapy himself. But what about kids who don’t have fathers who are involved or live at home? How do mothers compensate? And what about gender? So far there is no evidence that boys are more susceptible to the father’s signals than are girls, but is this really so? And what about other male figures – male teachers, older brothers, uncles, grandfathers – are they equally influential? At what age is paternal influence on sociability strongest? And are paternal genes more influential here too?

Further research is warranted. Until then, we can wonder about the great socialites in history – the Jackie Os, Andy Warhols, Paris Hiltons, Truman Capotes, Gloria Vanderbilts, Nan Kempners, and Ivana Trumps. Did they get it from their dads?

 

 

 

How big is your limbal ring?

Posted in news, psychology, science, sex by jenapincott on April 30, 2011

Of all the qualities that give an attractive person an edge, here’s one you’ve likely overseen:  the limbal ring,  the dark circle around iris.  The limbal ring is the line that separates the colored part of the eye from the white (the sclera).   

It’s completely unconscious, the way we all judge others’ limbal rings. In the 20 milliseconds or so it takes to assess a person’s attractiveness, you’re factoring in the size and shade of the limbal rings. The bigger and blacker they are, the more attractive the eyes. People with the prettiest eyes have the most prominent limbal rings.  

This, anyhow, is the upshot of a recent study by Darren Peshek and his colleagues at the Department of Cognitive Science at the University of California at Irvine. The researchers showed volunteers eighty pairs of male and female faces.  Each pair of faces was identical except the eyes: one had dark limbal rings and the other had no limbal rings.  The volunteers were asked to pick which face was more attractive and to indicate their degree of preference.

Men thought women with the dark limbal rings were more attractive than those without, and women thought the same of men with dark limbal rings.  Men and women also judged faces of the same sex as more attractive when the limbal rings were large.

Looking into my baby daughter’s eyes, I see the blue of her iris is framed by a thick black limbal ring.  The contrast makes the white of her eyes so white they look blue. The very young have the thickest, darkest limbal rings.

Which is exactly the point.  The limbal ring serves as an honest signal of youth and health-desirable qualities, reproductively speaking. The ring fades with age and with medical problems.  It’s thickest from infancy through the early twenties.  A thick, dark limbal ring may make us appear younger.  It makes the whites of the eyes whiter.  This might be why so many people think light eyes are so sexy:  the limbal ring, when present, shows up more.  

There are so many ways to fake the appearance of youth. You can wear makeup and wigs and get tummy tucks, plastic surgery, Botox, and boob jobs.

But a fake limbal ring?

Yes, this too. Long ago, Japanese schoolgirls discovered the edge a limbal ring can give you by wearing “limbal ring” contact lenses. They make the eye look bigger and more defined. And while you’re eyeing these contacts, you might as well buy a set that expands your pupils too. Big, dark, dilated pupils signal emotional arousal. They, too, act on the unconscious favorably.

The limbal ring is well-named. Limbis means border or edge, and it’s related to limbic, meaning emotion or drives. The limbal ring, seen from inches away, is an intimacy zone. Don’t flirt until you see the whites of their eyes.

Why are Redheads More Sensitive?

Posted in psychology, science by jenapincott on April 16, 2011

Redheads may be hotheads, but they get colder faster. They also bruise more easily. And they feel more pain.

All this comes from a series of studies done in the last few years on people with genes for red hair. A true redhead produces an abundance of a yellow-red pigment called pheomelanin. (Brunettes produce the more common eumelanin, a dark brown pigment.) A redhead’s prodigious pheomelanin output is the result of mutations, or variants, of the MC1R.3 gene. Redheads have two copies of this variant allele, one from each parent.

So what does this “redhead gene” have to do with sensitivity? The same gene is involved in the body’s perception of pain. Edwin Liem, an anesthesiologist at the University of Louisville, suspects that when both copies of the MC1R.3 gene are variants, as they are in redheads, receptors in the nervous system modulate pain more intensely.  It’s also possible, according to Liem, that the redhead version the MC1R gene also directly affects hormones that stimulate pain receptors in the brain.

In one study, Liem and his colleagues compared the pain tolerance of sixty naturally red-haired volunteers with sixty brunettes. The redheads reported that they felt a chilling pain at around 6 degrees C (43 degrees F), unlike the volunteers with dark hair. Brunettes did not feel an aching chill until the temperature approached freezing.

In another experiment, also led by Liem, women with various hair color types were exposed to electric shock. Turns out, the redheads needed about 20 percent more anesthetic to relieve the pain (confirming the common belief among anesthesiologists that redheads are tough to knock out). While redheads have normal blood counts and coagulate blood the same as anyone else, they bruise more easily. Yet another study found that redheads are more than twice as likely as women with other hair colors to fear and avoid the dentist.

These studies have been done on women only, and it’s unknown whether red-haired men would have the same outcome. (However, there’s evidence that pain pathways differ between the sexes.)

Redheads are stereotyped as being hot-headed, tempestuous, dramatic, high-strung. Is it possible that a genetic sensitivity to pain can affect temperament? It’s fun to speculate. For some, physical pain may translate into emotional pain. Sensitivity may tip over into volatility. Could a fiery, short temper even be a pain avoidance mechanism? Why not–after all, a good offense can be the best defense.


Why are Men Mad About Mammaries?

Posted in news, psychology, science, sex by jenapincott on April 3, 2011

Why do men love breasts?

Let me count the theories:

1. Freudian (breasts remind men of their moms and the nurturing of childhood)
2. Evolutionary (breasts resemble buttocks, and prehuman ancestors always mounted from behind)
3. Reproductive (breasts are an indicator of age, and big breasts in particular are a marker of high estrogen levels, associated with fertility).

Do these reasons sufficiently explain why breasts are beloved — even in cultures that don’t eroticize them any more than the face?

If not, here’s another:

Breasts facilitate “pair-bonding” between couples. Men evolved to love breasts because women are likelier to have sex with — and/or become attached to — lovers who handle their breasts.

This idea came up in New York Times journalist John Tierney’s interview with Larry Young, a neuroscientist famous for his research on monogamy. According to Young, “[M]ore attention to breasts could help build long-term bonds through a ‘cocktail of ancient neuropeptides,’ like the oxytocin released during foreplay or orgasm.”

The same oxytocin circuit, he notes, is activated when a woman nurses her infant.

When women’s breasts are suckled, as they are during breastfeeding, the hormone oxytocin is released. Oxytocin makes the mother feel good and helps her bond with her baby. She feels loving and attached. The same reaction might happen if a man sucks and caresses a woman’s breasts during foreplay. In our ancestral past, the most titillated men may have been the ones to attract and retain mates and pass on their genes.

The “boobs-help-bonding” theory may not be the strongest explanation of why men love breasts, but it’s worth introducing to the debate. That said, there are many ladies out there for whom a lover’s suckling does nothing — and there are many breast-ogling boobs who know nothing of foreplay.

What Singles Can Learn from Baby Talk

Posted in news, psychology, science by jenapincott on March 28, 2011

When you become a new parent you get a lot of advice on how to connect with your infant. To win her over, you’re told, talk the way she talks.  If Baby says “bah-bah-bah,” you say, “bah-bah-bah” back. You can make your “bah” sound like a real word by saying BAH-tel” or “BAH-th.” The content doesn’t really matter.  You just need make sure you sound like her.  Researchers call this “language style matching.” It draws the infant in and helps her connect with you. Experts can predict a baby’s attachment to her mother by how much they bah-bah back and forth during baby talk.

            Singles seeking love and connection can learn from this, according to a new study led by James Pennebaker and Molly Ireland at the University of Texas at Austin, and their colleagues at Northwestern University.  What the psychologists investigated is whether people on a first date who use similar words hit it off better than those who don’t.  Could language style predict whether you and your date will decide to see each other again and even have a strong and stable relationship eventually?

            To find out, the researchers recorded college students on speed dates. Thrown together for four-minute pairings, the men and women warmed up by asking each other the usual questions:  Where are you from?  What’s your major? How do you like college?

 Using a computer algorithm to analyze the speed-daters’ conversations, Pennebaker and Ireland found that men and women that wanted to see each other again matched each other’s function words significantly more often than those that had no interest in each other. Function words are like glue. They are not nouns or words; rather, they show how those words relate.  They are words like the, a, be, anything, that, will, him, and well. They are the yeses and okays and the pauses and interjections between words. They are the ifs, ands, and buts. By themselves they don’t sound like much, but they set a mood.

            The more a couple’s language styles matched, especially the function words, the likelier they were to hit it off. Couple whose speaking styles were in sync more than average were nearly four times as likely to desire a second date as those that were not.  About 77 percent of similar-sounding speed-daters desired a second date compared to only about half the dissimilar speakers.  Similar-speakers were also significantly more likely to be dating three months later.

            Language style matching is usually unconscious, according to the researchers.  It’s verbal body language.  Just as couples on the most successful dates make more eye contact, lean in toward one another, and otherwise echo each other’s body movements, they also echo each other’s choice of words.  We put ourselves in sync with people with whom we want to get close and stay close. 

Pennebaker and his team also used the alogrithm to test written correspondence for language style, and found that couples who had been dating a year or more were likelier to stay together if their writing styles in text messages matched. 

You can predict if you and your date or partner are in sync by taking Pennebakers’s online test at http://www.utpsyc.org/synch/.   Enter your and your love’s email or text correspondence and you’ll get a number that assesses how much your language matches up — which in turn may predict how well your relationship will hold up.

**
If you and your partner use actual baby talk to communicate — that is, speaking in a high-pitched voice with elongated syllables to your ickle-bitty-peshus wuv –you may have an especially healthy long-term relationship. According to a study by researchers Meredith Bombar and Lawrence Littig, baby talk helps lovers enhance feelings of mutual intimacy and attachment to each other.  Compared to other couples, babytalkers are more secure and less avoidant in romantic relationships.

Why?  In effect, baby talk, when mutual, is not only a form of language style matching but also a way to reactivate primal circuits of attachment. It taps into the unconditional love of a parent for child.

The old “play” circuits are activated; as in any form of fantasy, baby talk allows a couple to step outside the limits of self, space, and time. Stress is reduced — the same reason why a recent study on light S&M found that couples who spank together stay together. Babytalking lovers get a blast of dopamine and oxytocin in areas of the brain involved in reward and bonding — the ventral tegmental area, orbitofrontal cortex, and anterior cingulate cortex.

Mutual use of high-pitched voices, soothing whispers, cooing, lisping, and making expressive faces is also a way of “looping” or “mirroring” affection. Along with the other bonding benefits, baby talk may be a way of flaunting one’s healthy emotional neural circuitry — suggesting not only love and commitment but also strong nurturing instincts.

Do babytalking couples make better parents?  Who knows — but secure, loving, long-term ones do.

Do Brothers Stall Their Sisters’ Sex Lives?

Posted in parenting, psychology, science by jenapincott on March 20, 2011

Nearly eight months ago I gave birth to a baby girl. The child is now a seam-popping twenty-plus pounds. Infants, they grow so quickly it’s creepy — my thoughts fast-forward through her teething years to the teens, and I’m terrified. Problem is, my family lives in New York City where children want to be adults. The weenies of tweens should stay in their jeans, but all too often they don’t.

The onset of girls’ sexual maturity depends a lot on the social environment — peers, culture, and so on. A recent study by Australian behavioral ecologists Fritha Milne and Debra Judge found that it especially depends on the family environment, and not in the expected ways of curfews and chastity pledges. Sure, if you’re a teenage girl your parents might hold you back from trying to lose your virginity. So may your grandparents and any other authority figure in your family.

But so might your little brother.

Milne and Judge recruited nearly two hundred women and seventy-six men, all living in or around the city of Perth, Australia, and asked them questions about their family lives and sexual development. The results were that girls with only younger brothers lost their virginity an average of more than a year later (at age 18.3) than girls with younger sisters only. Girls with both younger brothers and sisters lost it nearly two years later on average (age 19.3) than girls with no younger siblings. Younger sisters alone had no impact.

The chastity effect only applied to girls with younger brothers. Having a big brother (or sister) didn’t make a girl any less likely to hold onto her virginity, yet another strange pattern emerged. This one involved the girls’ physical maturity.

The more older brothers a girl had, the later she got her first period. Girls with only elder brothers got their first visit from “Aunt Flo” up to a year later (at age 13.6) than girls with older sisters or no older siblings (age 12.7). (This is meaningful given that breast cancer and other conditions are related to earlier menstruation.)

Elder brothers delay physiological maturation, while younger brothers delay behavioral maturation.

What’s going on?

Trained as behavioral ecologists, Milne and Judge took a look at the big picture. Daughters are often caregivers. Historically, as has been found in traditional societies, a woman with daughters as first- or second-born children has a larger family than a mom whose first children were sons. Elder daughters take care of younger siblings, which frees up Mom to keep popping them out. Boys historically required more resources than do girls, which made big sister’s contributions even more important. As a result, these helpful elder daughters experience a delay in starting their own families. In the modern world where women don’t usually start their families until their mid-twenties on average, this is no problem, but in the past females with brothers may have had fewer children over their lifetimes.

The bigger mystery is what’s actually behind Big- and Little Brother’s stalling effect on their sisters’ sexuality. This is unknown territory, so Milne and Judge tread lightly here. The safest theory is that the delays are behavioral. Girls with little brothers lose their virginity later because they’re too busy taking care of their siblings to have love lives of their own. Perhaps little brothers, who are slower than female siblings to develop and reach puberty, keep their elder sisters in a more childish mindset. Or perhaps the stress of care-giving slows down puberty.

The researchers should also consider a much more surprising yet equally plausible theory: brothers send out chemical cues (pheromones) in their sweat that inhibit their sisters’ sexual development. Odd as it sounds, this would explain the perplexing finding that girls with older brothers get their first periods later than their peers. And, it appears, so do girls who grow up with their biological fathers in the household, compared to their peers with absent dads. Several studies, including here and here and a large one at Penn State that involved over nineteen hundred college students, came to this conclusion. (Interestingly, the same study found that girls growing up in homes with males unrelated to them got their periods earlier than average.)

The sweat-stifles-sexuality theory isn’t as far-fetched as it sounds. Other animals — rodents, for instance — use pheromones to modulate sexual maturity and fertility in a population. Over the years, a girl would inhale chemical cues in fraternal sweat — think of all those sock and armpit odors. Those chemicals would hit the hypothalamus of her brain where sex hormones are produced, and slow down the works. Puberty strikes a little later. Evolutionarily speaking, the result is that a girl could stay in the family nest longer without conflict. The risk of incest is reduced.

So should I try for son now? Truth is, the data applies to populations, not individuals. There are no guarantees; these are just interesting findings that deserve more research. Moreover, I’m in over my head right now with my baby girl’s teething and feeding challenges. Sure, I’ll want preserve her girlhood for longer than a New York minute. But I also need to preserve my sanity

 

Do baby tears have mind-control properties?

Posted in news, psychology, science, sex by jenapincott on March 8, 2011

A few weeks ago, Israeli neuroscientists Shani Gelstein and Noam Sobel published a study about mind-control properties in human tears. The gist of the research, which enjoyed much media attention, is that women’s tears contain a chemical signal that reduces sexual desire in men. Tears were collected from the cheeks of emotionally-distraught women watching sad films and wiped on the upper lips of male volunteers. Compared to men who whiffed a salt solution control, the tear-sniffers not only had a reduced sex drive but also lower testosterone levels and reduced brain activity.

A leading explanation is that chemicals in tears generally reduce male aggression, making them more sympathetic.

How does this work? One theory is that one or more of the hundreds of chemicals in tears has “mind-control” properties, triggering specific predictable behaviors in others. (Here and here I write about how this happens in sweat, too.) One candidate is prolactin, a hormone associated with bonding. When inhaled in a person’s tears, prolactin may affect the sniffer’s hypothalamus, the part of the brain that produces hormones which in turn affect behavior.

Baby tears have not been the subject of a study yet (hopefully soon). But it’s not a far cry from certain that if there are chemicals in the tears of women that affect men, there are also chemical triggers in the tears of babies that affect their caregivers or anyone else that comes into contact with them. These tears may trigger care-giving instincts and reduce aggression toward the screaming infant.

I wonder: Infant abuse is relatively uncommon given how irritating a screaming baby can be. Are the people guilty of this crime more likely to be amnosiacs (loss of smell-sense) or have another form of brain damage that would prevent them from inhaling aggression-reducing signals in the baby’s tears?

Another theory: Kids cry all the time and sometimes it’s hard to tell when they really need attention. Might chemicals in emotional tears direct parents to respond appropriately when there is a real need for attention? Assume these chemical signals are only in emotional tears–not crocodile tears or sleepy-time tears. Do they help us intuitively know when it’s OK to let a child cry it out instead of rushing to soothe her?

What your date’s fingerprints reveal

Posted in news, psychology, science, sex by jenapincott on February 6, 2011

Not long ago, people everywhere started to do the “finger game” on a first date. This is not as naughty as it sounds. As I describe in BLONDES, the finger game involves asking your companion for a look at his (or her) right hand. If his ring finger is longer than his index finger it’s a sign of prenatal exposure to high levels of testosterone. People with longer ring (than index) fingers are likelier to be more aggressive, better at sports, and more musically inclined. They may have more sex partners in life.

Now you can take the game to the next level: fingerprints.

Take a close look at the ridges on your companion’s fingers. (Actually, they’re best seen under a magnifying lens or photocopied and enlarged.) Most people have slightly more ridges on the fingers of one hand than the other.

More ridges on the right-hand fingers: This indicates higher levels of prenatal testosterone. He or she might master mental rotation – knowing which one of four abstract figures, revolved in three-dimensional mindspace, matches a diagram (a “masculine” task). Right-ridge dominant people are also better at aiming at a target and getting a bull’s eye.

More ridges on the left-hand fingers:
This indicates lower levels of prenatal exposure. He or she may be a whiz at games like word associations, taking a word like clear and coming up with glass then Philip then opera then ghost, or naming as many round objects as she can in three minutes (considered “feminine” tasks). Compared to straight men, gay men have more ridges on their left pinkies and thumbs.

Four or more ridges on the fingers of one hand than the other: This reflects how much stress your companion weathered when he or she was a second-trimester fetus. For instance, researchers found that women who were 14-22 weeks pregnant when an epic ice storm hit Canada were more likely to have babies whose ridge counts varied greatly between hands. In nature, dramatic asymmetry is often a sign that the fetus has been stressed in some way. The more stress, the less symmetry. In fact, those with significantly asymmetric ridge counts between right and left hands were more likely to score lower in language and intellectual development as toddlers. Both fingerprint development and the brain may have been affected by constriction of blood flow to the placenta or stress hormone levels.

Other ridge count studies have also found interesting correlations: a significant difference between the ring and pinky fingers of the right hand is associated with less muscle mass in the lower extremities and a bulked-up upper body, including a thicker waist. A difference of around three or four more ridges between the thumb and pinky fingers is also associated with diabetes later in life. Asymmetries are also connected to cleft lip, dyslexia, schizophrenia, infections, and other prenatal problems.

Around ten weeks after conception is when the bottom (basal) layer of fetal skin outgrows the top (epidermis), and the tension between the two causes the skin to buckle. At this time fingerprints are like wet cement: any disturbance until mid- pregnancy may leave a lifelong impression. At this time the skin and the brain are both are made of the same raw material — fetal ectodermal tissue. Any disruptive event in the womb left its mark on both. This means that fingerprints give us clues about the brain.

You would like to know more about the minds of the people you date, which is why you’re analyzing their fingers. Of course if you could read their minds, you’d know they think you’re crazy.

Do you carry DNA of former lovers in your body?

Posted in pregnancy, psychology, science, sex by jenapincott on January 28, 2011

This bit of science arcanum is especially cringe-worthy.

Many years ago, scientists first discovered that a large minority of women have Y-chromosome gene sequences in their blood. At first glance, this seems strange. Men are born with Y-chromosomes but most women are not. The male cells in these women must’ve come from somewhere else.

But where?

The most obvious source is a fetus. Nearly every woman who has ever been pregnant or had a baby has cells from her fetus circulating in her bloodstream. These cells filter through the placenta and reside in the mother’s bloodstream and/or organs — including her heart and brain — for the rest of her life. This condition is called microchimerism, named after the Greek chimera, a creature composed of the parts of multiple animals. Pregnancy-related microchimerism explains why women with sons would have Y-chromosome sequences in their blood.

This is fascinating enough. But how do you explain why women without sons also have male cells circulating in their bloodstream?

This was the subject of a study by immunologists at the Fred Hutchinson Cancer Center. They took blood samples from 120 women without sons and found that 21 percent of them had male DNA. Women were then categorized into four groups according to pregnancy history: women with daughters only, spontaneous abortions, induced abortions, and no children/no abortions.

While the number of women bearing male DNA was highest in the groups that had abortions (nearly 80 percent), women who had only girls or no babies (20 percent) also had male cells in their blood. For no apparent reason.

There are other reasons why women in the fourth group carried male cells: inherited in the womb from a male twin that passed, from a miscarriage they did not know about, from their mother via an older brother…

Or through sexual intercourse.

There remains a possibility, however remote, that cells from a lover may pass be transmitted during sex. Those cells may hang out forever in the recipient’s body, taking residence in any organ. These cells are the imprint of lovers past, a trace of living history.

Might a woman’s bodily fluids enter a cut in a man’s genitals as well? Could men carry around the genes of women they’ve slept with?

The imagination is stirred. What are those foreign cells doing in hearts and minds? Are they wreaking havoc in our heads? Do the cells of former lovers clash? In a science fiction scenario a person could even take a drop of her own blood, isolate a cell from her former boyfriend, and clone him. Then do with him what she will.

The upshot of this research? It’s yet another reason to use a condom.

Why Your Brain Is Better in Love

Posted in media by jenapincott on January 8, 2011

A re-post of my interview with David DiSalvo on his fascinating Neuronarrative column at Psychology Today.

あなたがその人を捕まえたいと思ったら?

Posted in news by jenapincott on November 22, 2010

BLONDES — now in Japanese!

Mají páni radši blondýnky?

Posted in media by jenapincott on November 12, 2010

Now in Czech by Jena Pincottová!

Guardian’s Internet pick for “sex research revelations”

Posted in media by jenapincott on August 23, 2010

Today the Guardian selected this blog as one of its Internet Picks of the Week!

I will return from my hiatus soon….Stay posted.

Perks and perils of the Pill?

Posted in news by jenapincott on August 7, 2010

I spoke to the blogger Rachel Rabbit White about the psychological impact of birth control, and here’s her article.

On a personal note, I’m busy with a newborn so posts will be (temporarily) less frequent…..

“Blondes” in the Washington Post

Posted in media, news by jenapincott on July 11, 2010

At 40+ weeks pregnant still happy to talk about men’s bodies….Here’s a fun article in today’s WaPo on the hot soccer players of the World Cup, with mention of BLONDES.

Do employers prefer blondes?

Posted in news by jenapincott on June 17, 2010

Earlier this month I was sent a new study that found that there’s yet another bonus of being blonde, and this one is unexpected: Blondes get paid more than women with any other hair color. This surprised me, and so I read further.

David Johnston, an economist at Queensland University in Australia, scoured a database of 12,686 Caucasian women ages 25 and older living in the United States. The database identified the natural hair color of each woman [light blonde (1.6%), blonde (19.0%), light brown (21.8%), brown (51.2%), black (2.4%) and red (4.0%)], their hourly wages, their marital status, their husbands’ hourly wages, and their education level. Johnston controlled for height, weight, eye color, education, and other variables.

Contrary to the (silly) perception that blondes are dumb, the data reveal that they have as much education as women of any other hair color. But, interestingly, they earn 7 percent more than women with any other hair color — the market equivalent of an extra year of education. (For the same job that pays darker-haired women $50,000 yearly, blondes would get paid $53,500). No other hair color but blond appears to influence a woman’s salary.

Blondes in the marriage market also appear to get a monetary boost. The data show that blondes marry men who earn 6 percent more on average than the husbands of women with other hair colors. Blondes appear to attract and marry higher-earners. Or wealthier men appear to marry blondes.

Johnston speculates tepidly on the reasons why blondes appear to have an advantage wage-wise. Skin color is one. Although all the women were Caucasian, natural blondes may have fairer skin, associated with countries with a strong work ethic (Northern European).

More plausibly, he cites attractiveness as a paycheck-plumper. Blondes may be perceived as prettier, and beauties are known to get paid more than plain Janes. Even if they aren’t inherently more beautiful, blondes, boosted by public perception, may be more confident, social, and therefore have better communication skills. They may be (wrongly) perceived as being more productive and valuable as employees.

What Johnston doesn’t break down are the types of occupations in which the women are employed. Among waitresses, dancers, Fox newscasters, and Mary Kay saleswomen, perhaps blond hair is a bonus. But do blond doctors and librarians, physicists and writers really earn more than their darker-haired colleagues? I hope not.

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