Tag: hormones

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.

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?

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…..

“Cheating gene” mouth swab test available

Posted in news by jenapincott on May 8, 2010


In BLONDES and in this post I write about the so-called “cheating gene.”

Not long ago, Hasse Walum, a handsome post-graduate at the Karolinska Institute in Sweden, decided to study the association between a particular gene for what is called a vasopressin receptor and relationship stability. He analyzed the responses of over 550 twins and their partners to questions, some of them intrusive, about their relationships: How often do you kiss your mate? “Have you ever regretted getting married/moving in?” “Have you discussed a divorce or separation with a close friend?” “Rate your degree of happiness in your relationship on a scale of 1-7.”

Walum then sampled the men’s DNA. Getting DNA from the men was simple. You don’t need blood to have access to another person’s genome, just saliva, which the men submitted in a mouth swab.

What Walum discovered was stunning. Focusing on one particular vasopressin receptor gene variant, allele 334, he found that the more copies of it a man had, the weaker his bond with his partner. Men who lacked the gene variant were generally happiest in their relationships — only 15 percent of them had a crisis. Men with one copy were slightly more likely to have marital problems. And men with two copies were, on average, twice as likely to have had a relationship crisis in the past year than men who didn’t have the variant — meaning that 34 percent of them, or one in three, were headed toward a break up. Their partners agreed. Women whose partners carried one or two copies of the allele 334 variant were generally less satisfied with their men, probably because they generally scored as less affectionate than other guys.

Walum also found that men with two copies of the variant were nearly twice as likely not to marry their partners and mothers of their children as men who had no copies of the variant. This suggests that there is something slightly different about the vasopressin receptors in the brains of men who struggle in their roles as partners and fathers. These men may have more difficulty bonding with other people, including their wives and kids.

I imagine that some of you are now scheming to get an allele 334 test for your man. Of the more than five hundred women who responded to my online poll on this topic, nearly 65 percent said they would test their man if given the option.

And now you can. Yes, you can order a saliva test for allele 334 of the AVPR1A gene for $99 from Genesis Biolabs. (I can’t vouch for the lab. I’m reporting for entertainment purposes.)

Ladies, there’s a caveat here, of course. Even if there’s a correlation between this particular gene variant and a man’s behavior, it doesn’t account for all men. Just as the “god gene” and “gay gene” are met with skepticism in the scientific community, so is the “cheating gene.” Even within Walum’s study, there were men with two allele 334 variants who were happy husbands and fathers, and there were men without the variant who were miserable in their relationships. The statistics apply to populations, not individuals, who are also influenced by a other factors — parental role models, partner choice, opportunity to cheat, past loves, age, life satisfaction, religion, hormone levels, and so on.

A two-allele man may become a number one husband under the right circumstances.

But it’s your call. Swab him and then decide?

How could you possibly be pregnant and not know it?

Posted in pregnancy by jenapincott on April 10, 2010

Now at the start of third trimester, I find it inconceivable that there are women at this stage — and beyond — who still do not know they’re pregnant.

Here are the astonishing statistics: 1 in 455 women doesn’t know she’s pregnant until after week twenty, and 1 in 2,500 is oblivious until she actually goes into labor. The latter are known to give birth, without medical assistance and in agonizing pain, in Walmart bathrooms and at proms, in dorm rooms and in their own bathrooms. They had no idea they were pregnant because they had irregular periods, have been on birth control pills, are in perimenopause, have had menstrual-like bleeding, and/or are overweight and less sensitive to weight gain.

But I know what you’re thinking because I’ve thought it too: it’s denial. On some level the ladies must’ve known they were pregnant but couldn’t deal with the reality.

Yet the more I explore the origins of cryptic pregnancy, as the condition is clinically called, I realize that denial or mental illness doesn’t explain most of the cases. Only a minority of cryptic pregnancy cases has been attributed to personality disturbances (8 percent) or schizophrenia (5 percent). It appears that most of these women are perfectly sane, educated, and in stable relationships. Quite simply, they do not know they’re pregnant because they have no symptoms — no weight gain, no nausea, and little to no abdominal swelling. Or the symptoms are so subtle as to be easily mistaken for something else.

Every pregnancy is a tug-of-war of resources between Mom and fetus. Each has her self-interest in mind. Most of the time the tug-of-war ends up in a happy equilibrium. Mom provides enough nutrients, but not too much too handicap herself. But sometimes Mom gets more rope….at the expense of the fetus.

According to evolutionary psychologist Marco Del Giudice this might happen in a few ways. For one, the fetus might not be putting out enough signals that it exists and needs resources. One way fetuses announce their existence is through HCG, the hormone that makes a home pregnancy test turn positive. In many cases, the higher the HCG, the more severe the morning sickness and other symptoms. A baby that produces a scant amount amounts of HCG might go “under the radar,” failing the pregnancy test and going unnoticed by the mother — physiologically and psychologically. This would mean the baby gets fewer resources than she otherwise would. The lack of HCG signaling in cryptic pregnancies explains why these babies are so often born preterm, underweight, and small for their gestational age. They didn’t ask for more resources from Mom, and they didn’t get any.

There are a few reasons why a baby wouldn’t produce enough HCG. One is chromosomal anomalies; that is, the fetus has a birth defect and is in danger of miscarrying. It’s also possible that an otherwise healthy fetus simply puts out low quantities of the hormone due to a genetic quirk.

Or, here’s an interesting theory: Maybe Mom has stress and relationship problems. In this case, biologically speaking, it may be in the fetus’s best interest for the mother to be completely oblivious to the fact that she’s carrying to prevent being rejected and miscarried, which may happen when a woman is stressed. As Del Giudice points out, in our evolutionary past a woman who did not know she was pregnant and had few to no symptoms could conserve precious energy. She would be able to move freely and eat food of any kind, and as a result be better able to survive in the face of stresses and threats. In this case, babies may put out less HCG or stressed-out moms may unconsciously lower their sensitivity to the hormones.

Seen this way, cryptic pregnancy is an adaptive “emergency” mechanism — essentially, the fetus sensing a threat and striking a bargain with the mother by demanding little and laying low. When the normal stresses of pregnancy might otherwise trigger a miscarriage, this “stealth strategy” allows the fetus to survive.

The case for wearing blush

Posted in news by jenapincott on January 24, 2010

Bad news for pale girls like me: red is hot. Not only do studies find that men are more attracted to women in red, now we find that men prefer women who are red. Their cheeks, that is….

In a new study, evolutionary psychologist Ian Stephen and his colleagues at the Face Perception Lab recruited volunteers of various races and asked them to digitally adjust the color tone on more than 50 faces to make them look as healthy and attractive as possible. Volunteers consistently added more red coloring to the cheeks — whether the face was Caucasian, Asian, or Black. The redder the face, the more suggestive it is of oxygen-rich blood reaching the skin. The more oxygen-rich blood, the more suggestive it is of the person’s general health and youth. An old person, a sick person, a person with hypertension or bad circulation…will not get rosy-cheeked.

And not only is a flush suggestive of good health and fitness….but high sex hormones as well. In women in particular, high levels of estrogen may cause an expansion of tiny blood vessels under the skin. Hence, rosy cheeks. As in monkeys, female facial redness may be associated with fertility and reproductive quality.

As Stephen points out, the human eye has evolved to pick up on fine variations on the color red. “People are sensitive to the subtle color difference between oxygenated and deoxygenated blood (oxygenated blood is a bright red colour, deoxygenated blood has a slightly bluish red colour, and we interpret this difference in skin blood oxygenation colour as a cue to the health status of individuals.”)

But why did the researchers find that volunteers preferred women over men with rosy cheeks? One reason may be the sex hormones, which show up more obviously in flushed female faces. But it may also be due to the fact that men already have ruddier faces than women do — they have higher levels of hemoglobin and arterial oxygen content in their blood. As a result, the male blush is not as obvious a cue of good health and high sex hormones.

There are surely other reasons why a maidenly blush is attractive, as I describe in BLONDES. For one, a flash of color to a woman’s cheeks may suggest youth, modesty, embarrassment, excitement…all of which, depending on context, may appeal to red-blooded men.

Do hypochondriacs prefer macho men?

Posted in news by jenapincott on January 8, 2010

Evolutionary psychologists tell us that one of the reasons why women find masculinity attractive is that high testosterone is a sign of a strong immune system. A strong immune system, in turn, in a sign of good genes and childhood development (testosterone is an immunosuppressant and only men with good genes can overcome its drawbacks). These strong square-jawed macho men aren’t necessarily good dads: they’re more likely to be uncooperative, combative, and aggressive. But they may offer good genetic material for your kids, depending on the circumstances.

So how do you prove that women equate masculinity with good genes and healthy immune systems (subconsciously, at least)? An indirect approach was taken by Lisa DeBruine and her colleagues at the Face Research Lab at the University of Aberdeen. (The Lab conducts many fascinating studies on attraction, some of which I reference in BLONDES.)

In this new study, DeBruine recruited 345 women of all ages to rate faces. The faces were digitally altered, and ranged from very masculine to very feminine. Participants also completed a test called the Three-Domain Disgust scale, designed to measure moral disgust (deceiving a friend), sexual disgust (hearing strangers have sex), and pathogen disgust (stepping on poop).

Turns out that women’s preference for masculinity in male faces was correlated with disgust sensitivity to pathogens, but not in the moral and sexual domains. (Yes, hypochondriacs do prefer macho men!) DeBruine speculates that in certain situations, such as disease-ridden environments, women are wired to prefer high-testosterone males. The benefits of their good immune system genes are worth the tradeoff.

The testosterone-means-good-genes theory, anyway, may explain why women in disease-ridden environments are likelier to choose macho guys. Explains DeBruine et al.:

Because a partner’s heritable health is of greater value when pathogens are a greater concern, concern about pathogens is likely to also be a factor that contributes to the resolution of this tradeoff. Cross-cultural differences in mate preferences and mating systems vary consistently with differences in pathogen prevalence. When people from 29 different cultures were asked to rank a series of attributes based on how important they would be in a mate, people in areas with a high prevalence of pathogens ranked physical attractiveness higher than people in areas with a relatively low prevalence of pathogens did. Also consistent with these
findings, rural Jamaican women prefer masculinity more than British women do…

So do hypochondriacs, fearful of disease, marry more macho men (e.g. self-professed hypochondriac Susie Essman and her new husband?) As environments become more sterile, will we prefer men with softer, sweeter faces and personalities? Or will the next swine flu outbreak inspire us to pursue pigs?

When the perfect woman is genetically male

Posted in news by jenapincott on June 1, 2009

42-20487063Years ago, in college, I met the perfect woman. Or perhaps a man’s idea of the perfect woman. She had flawless and dewy skin, angular cheekbones, a cinched waist, milkmaid breasts, long legs, dove-like hands, lush long hair. Wherever she went, people swiveled their necks and stared. She was a fantasy, a vision. A goddess.

And she was miserable.

It emerged that the source of her pain was a secret that she kept until she enrolled in a radical gender studies class. Inspired, she came to terms with her identity, and in the telling she liberated herself. Her secret was that she wasn’t technically female. She had a condition known as androgen insensitivity syndrome (AIS). She was the perfect woman on the outside, and inside she felt perfectly female. But she was genetically male (XY).

Her story was typical for women with complete AIS. At birth her doctors didn’t notice any difference in her genitalia. In high school she went from being a normal girl to an Amazonian queen. She was not only taller than her peers but curvier, too (some androgens are converted to estrogen which act on breast tissue). Unlike other girls, she never got acne or grew pubic or armpit hair (androgens regulate hair growth). She had no body odor. She got recruited as a runway model, was attracted to men and had many boyfriends (including a celebrity), and had sex, albeit painfully. But by age sixteen she didn’t get her period, so her mother brought her to the doctor and an astonishing discovery was made. She had undescended testes. Inside, she appeared male: no fallopian tubes, no uterus, no ovaries.

This gorgeous college student had complete androgen insensitivity syndrome. Women with this condition — approximately 1 in 20,000 — tend to be exceptionally tall and striking in appearance. AIS is caused by a recessive variant of the gene that codes for Androgen Receptor. Because the body is insensitive to the androgen testosterone, the usual male features — penis, testes, scrotum, etc. — are unable to develop. The default phenotype is female, so people with AIS have a vagina or “vaginal pouch” (although most AIS women require surgical expansion). If a woman with AIS were to get a blood test, her testosterone levels would be as high as any man’s, but her body can’t process the hormone. That’s why women with complete AIS are so feminine — arguably more so than other women. (Some people with AIS have only partial androgen insensitivity. Considered intersex, or hermaphrodites, they fall all along the spectrum between typically male and female and have a micropenis. Naturally, there’s much controversy about gender assignment at birth and estrogen or testosterone injections at puberty.)

Several women have revealed they have complete or partial AIS, including singer Eden Atwood and tennis player Sarah Gronert. Although impossible to confirm, several famous celebrities of the past are purported to have had AIS: Wallis Simpson (Edward may have given up the crown for her, but it is said they could never have sexual relations), Queen Elizabeth I, and Joan of Arc. Rumors of AIS abound, perhaps out of jealousy, whenever a celebrity is statuesque, beautiful, and lacking a biological child — Jamie Lee Curtis, Ann Coulter,and even Gisele Bunchen,among many other model types.

In a sense, complete AIS flies in the face of the evolutionary theory I write about in BLONDES. If straight men are drawn to slim waists, shapely breasts, lush scalp hair, sparse body hair, long legs, and flawless skin because those qualities represent high fertility, then AIS is the ultimate deception. As gorgeous as an AIS woman is, there’s no chance of conception. But this ultimately doesn’t matter. It’s the 21st century, and an important lesson must be learned: Femininity is about more than reproduction.

Hormones in 20 seconds or less

Posted in news by jenapincott on May 16, 2009

The_Notebook_Limited_Edition_DVD-Contest-Ryan_Gosling-Rachel_McAdamsWithin 20 seconds of encountering a beautiful woman, men have been shown to have a surge of two hormones: testosterone and cortisol. This makes good sense, evolutionarily speaking. As I describe in BLONDES, hormones mirror the subconscious mind. Testosterone promotes assertiveness and reflects increased sexual desire. Cortisol focuses motivation. Women are the choosier of the sexes, which means — generally, of course — that the onus is on men to flaunt and flatter or take other action to attract the woman.

But what do women do when they see an attractive man?

The same thing. Far from being passive observers, women also experience a hormonal riot within seconds of seeing a hot guy. This is true even if the man is an actor in a film, as indicated in a new study led by neuroscientist Hassan Lopez at Skidmore College. Lopez and his team showed 120 women one of four 20-minute videos, each with a different scenario: 1.) an attractive man courting a woman (a clip from The Notebook starring Ryan Gosling) exhibiting a dominant social presence, risk-taking, kindness to children, faithfulness, confidence, and humor 2.) a nature documentary about caves; 3.) an unattractive older man (Jack Nicholson) courting a woman 4.) an attractive woman (Cameron Diaz) with no man present. Saliva samples were taken right before and after each viewing.

Of all four groups, only the women watching the hot, desirable, “high mate value” guy trying to seduce a woman had a surge of testosterone and cortisol. The higher the hormones, the stronger the romantic/sexual interest the women reported. (Interestingly, women on birth control pills only experienced a cortisol surge, not testosterone, apparently because the pill suppresses the hormone. Naturally-cycling women also reported a greater willingness to engage in sexual activity and enter a relationship with the attractive man. This may be due to stronger hormonal surges in women who aren’t on the Pill or the fact that more Pill-takers are already taken.)

The study reminds us that hormones help both sexes focus and flirt more effectively, and a surge at the sight of an attractive prospect may change our moods in an instant. But what threshold must be met to trigger such a surge? Do women with higher baseline testosterone and cortisol levels respond faster and get turned on easier? Are high testosterone men more effective in raising women’s hormones? Could taking the Pill really decrease your natural attraction to handsome strangers? And when two people mutually elevate each other’s hormones within seconds, is that considered love at first sight — or just lust?

Archives

Connect on Facebook

Top Posts & Pages