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.

Are first-borns really the brightest?

Posted in psychology, science by jenapincott on January 20, 2011

For decades, researchers have observed that, on average, first-borns score higher on intelligence tests than their later-born siblings. This is nothing I’d brag about. I think it inspires resentment and eye-rolling among later-borns. But what many (not all) studies have found is that the further down a child is in birth order rank, the lower his or her IQ compared to older siblings. (Of course, intelligence tests and what they really measure are a controversial bugaboo in and of themselves, but let’s put that aside for now.) There’s no obvious reason for this because siblings often have the same parents and grow up in the same family environment.

The largest study on birth order and intelligence comes from Norway, where psychologist Petter Kristensen and Tor Bjerkedel studied data from a vast sample of more than 240,000 brothers conscripted by the military. Eldest children, it turned out, had an IQ nearly three points higher on average than the second-born siblings and about four points higher than third-borns, after controlling for parental education, marital status, income, mother’s age, and birth weight. (The effect of birth order on IQ does not differ for boys and girls.) A three-point difference in IQ doesn’t sound very significant from a personal perspective, but it is in the big picture. All else being equal, three points can translate into a thirty-point difference in SAT scores. That may make all the difference between admittance into an elite college or a second-tier one, for instance.

The IQ boost was strong when Kristensen compared scores between families (my first-born versus everyone else’s first-born, and my second-born versus all other second-borns and so on) and remained strong in a later study when he compared the scores of kids within families (my first-born versus my second-born versus my third-born and so on). This doesn’t mean that every first-born in every family was brighter. Many later-borns scored higher on IQ tests than their older sib. We’re talking about huge populations here, not individuals.

Even so, you’d think there is something special about the wombs of first-time mothers. It’s like a biological birthright, the first-born as know-it-all. They’re preachy and self-righteous. But they can be useful, too. They show the younger kids how to wheedle ice cream from an addled parent and properly glitter and glue. They know how to make killer snowballs, open a lemonade stand, and coax the dog to stand on its hind legs. They know what people do when they have sex.

t turns out that all this teaching and preaching that is key to Kristensen’s explanation of why first-borns score better on tests. Whether sanctimonious and bossy or generous and caring, the interaction between older and younger sibs helps the elder. They learn by telling. In tutoring others, we all make sense of the world, and this in turn affects how well we do on intelligence tests. “Smarter” comes from being the explainer. In Kristensen’s view, this explanation beats the other big three theories that involve family dynamics — first-borns get more parental attention and are exposed to a more intellectual environment longer; parents have higher expectations of them; and they’re more achievement-oriented. It beats them for one major reason that Kristensen discovered when he dug deeper.

The IQs of second-borns are higher in families in which the first-born has died.

Not only did the second-born rise in family rank when a first-born died, but also in IQ, topping the scores of any younger sibs. Third-borns moved into second-place IQ rank in their families (one point higher) in the few cases in which second-borns in a family died.

There are serious critics of the first-born-the-explainer explanation for higher IQs — especially those who insist there must be a biological reason why first-borns score higher. Although family dynamic can still play a role, there may be another sly and subtle culprit: the physical toll the first-born takes on the mother, and how quickly she recovers from it. Some studies have found that second-borns, especially those with older brothers, have lower birthweights. Significantly lower birth weights, in turn, may affect IQs if there are not enough maternal resources for the new baby. (It didn’t in the Norwegian study, but perhaps the data should be looked at more closely.) A deficit of omega-3s may be also to blame, according to one provocative theory. If Mom used up her store of these butt-based-brain-building fats on the previous baby and didn’t have time to replenish them naturally or supplement them in her diet, the next baby might suffer slightly.

But what can we really learn from this? We can imagine that birth order affects a baby throughout life, and performance on IQ tests is only a sliver of it. For those who buy into birth order psychology, even choice of career can be explained by one’s ranking in the family, which some studies confirm and others do not.

First-borns are said to be more conscientious, conservative, performance-and-power-oriented, disciplined, fearful of losing face, and generally more anxious. This helps explain why more first-borns are presidents, Nobel Laureates, and CEOs.

Every rank has its niche. Middle children are born to rebel. They are less conscientious, less religious, and don’t do as well in school. They’re more sociable, impulsive, and open to fantasy. They’re good negotiators. The babies of the family show more interest in others and are more empathetic. They’re more creative, flexible, risk-taking, impulsive and more extroverted, perhaps because they arrive into a larger, more stimulating household and must compete for attention. Children without siblings are similar to first-borns in that they tend to be ambitious and performance-oriented, but they are often lonely, independent individualists, or, depending on their situation, rely more on family. Kids who grew up with same-sex siblings have been found to be more conscientious and extroverted. Women who grew up with both a brother and sister tend to be more creative, while men tend to be more agreeable.

But is there anything about being a first-born or later-born that affects success and happiness in life? This is ultimately what matters most for our kids — and the answer is that birth order has no impact here. The planet needs explainers and extroverts, contemplatives and can-do types, rebels and realists, visionaries and ancillaries. What one achieves in the world, beyond birth order and standardized exams, is the real test.

Do more babies come out on a full moon?

Posted in news, pregnancy, science by jenapincott on January 12, 2011

Nature still has a subconscious sway over us, and labor brings out the inner animal. We know that circadian rhythms of night and day affect hormone levels, which in turn may trigger contractions. So it doesn’t surprise me when I hear midwives, nurses, and even doctors insist that more births occur on a full moon.

Their logic seems grounded: a full moon has a gravitational pull on amniotic fluid, just as it has on any other body of water. The pressure causes the sac to break, thereby triggering labor.

I’m not the only one who wanted to put this theory to the test. There are over a dozen studies published on labor and la lune (including here and here), totaling hundreds of thousands of spontaneous, non-induced births and hundreds of lunar cycles.

Alas, none have found any significant differences in the frequency of births, route of delivery, preterm delivery dates, or birth complications across the eight phases of the moon (or, for that matter, the weather). It’s a myth, albeit one that has only waxed and never waned – perhaps superstition causes us to see patterns where there are none.

I also found studies that show that contrary to common belief, psychiatric wards are not any busier during full moons than maternity wards. The moon doesn’t make us loonier or more likely to deliver. We do both all on our own.

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!

Would you eat your baby’s placenta?

Posted in news, polls, Polls and Surveys, pregnancy, science by jenapincott on November 14, 2010

“You’ve never seen a mother cat with postpartum depression, right?” a woman in my prenatal yoga class asked me. She had a challenging look in her eyes. Before I could respond she rushed to her punchline. “It’s because cats eat their placentas.”

The woman introduced herself as a doula-in-training who prepares placenta on the side. She thought I might be interested.

I learned that placentophagy, the act of eating the afterbirth, is common among other mammals. Animals probably eat it for the extra iron and other nutrients, to detract predators, or possibly to alleviate pain (not to thwart the kitty blues). My fellow yogi is among the small but passionate population of birthing specialists who believe that women should eat their placentas, too — especially to ward off postpartum depression. The placenta is rich in hormones: progesterone, estrogen, cortisol, and others. These hormones originate in the placenta, which means a woman’s levels take a plunge immediately after she gives birth. One theory of why women get depressed after birth is their hormone levels are low. Eating the placenta, it seems, could raise hormone levels enough to ward off depression.

I once bought a placental cream in New Zealand, and the hormones in it made my face break out in violent pustules. That doesn’t make me want to eat the stuff.

“It’s spongy like liver,” the woman said, going for the hard sell. She could use it in lieu of meat in any dish: a simple sauté, lasagna, meatloaf, anything. “Placenta” means “cake” in Latin because it’s round and flat; she could make it into a burger. If none of this appeals, she could have it freeze-dried, emulsified, and made into capsules.

“Oh, but I’m vegetarian,” I said, moving my eyes reverently in the direction of a Krishna wall hanging. But the doula-in-training was armed with a response. “Placenta,” she said, “isn’t meat that is killed.” She patted me reassuringly. “It’s OK!”

“I’m OK,” I automatically responded, as if already stuffed and passing on seconds. I didn’t want to burst her bubble, but sautéing, stir-frying, or even baking placenta would likely change the molecular structure of the hormones in it. I suspect she’d have difficulty attracting clients if they had to eat their bloody organ raw, sushi-style.

As it turned out, my obstetrician had a difficult time removing my placenta. Once out, I let my eyes linger on the silver platter it was heaped on. Weighing in at about a pound and a half, this grayish bloody sack fed and protected my daughter and manipulated me for the nearly ten months of pregnancy. It removed her waste. “It’s got to be tough,” I thought.

But regret came over me as I watched it leave the room. Should I have kept it, tried it? I reminded myself there is no proof that consumption of the placenta wards off serious depression or even the baby blues. Humans in traditional cultures only very rarely eat the afterbirth. Hippies ate it but chimps won’t. Many ethnic groups, honoring the placenta’s indispensability, bury it ceremoniously.

I admit a medical incinerator is not a respectful end. But neither is a vegetarian’s hostile gut. I hate to be close-minded, but my jaws are locked shut.

[Click here for an account of a woman who ate the placenta in the pic above.]

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Mají páni radši blondýnky?

Posted in media by jenapincott on November 12, 2010

Now in Czech by Jena Pincottová!

Is there a mommy gene?

Posted in news, pregnancy, science by jenapincott on October 17, 2010

At four o’clock in the morning, in the street in front of our home, I nearly lose it. Our three-week old has been crying for ten hours. I’ve wrestled her into a sling and am jumping up and down under a streetlight, singing “Amazing Grace” in agitated bursts.

Things have taken a turn for the worse. Earlier in the day when I lifted the baby up to my face, eyeball to eyeball, she jerked her head away and cried harder. The infant has been rocked and bounced, shushed and swaddled – with increasing force and desperation. It occurs to me that maybe I should ignore her for a spell. I could lay her down on the dewy grass, let her scream at the stars and the moon, while I drop my head in my hands and weep. How sweet the sound.

If there’s a mommy gene, I don’t have it.

Mommy genes! The idea started about fifteen years ago when a doctoral student named Jennifer Brown and her colleagues at Harvard Medical School noticed something wrong with their mice experiment. Pups were dying. Whole litters, in fact, were wiped out just a day or two after birth. This was strange, because the babies were healthy and so were the mothers. One glance at the mouse cage solved the mystery. Pups were scattered everywhere, shivering and starving, while the mothers nonchalantly went about their business. Normal mother mice round up their brood and feed and lick them. But these dams didn’t give a damn. They acted oblivious to their babies’ frantic squeaks.

The mother mice were specially bred to lack a gene called fosB. Brown and her colleagues had no idea that knocking out fosB would make mice into deadbeat moms, but it apparently does. It turns out that the gene, when activated, creates a protein that turns on other genes and is partly responsible for the function of neurons in the hypothalamus, a region of the brain that controls emotional behavior — including nurture. If you’re a murine mother, just being around your babies usually triggers the fosB gene to express itself. Because mother mice lacking a working copy of the gene are not motherly, fosB hit the headlines as the first “mommy gene.”

Several years later researchers found that genes called Peg 1/Mest and Peg3 also have an effect on the motherliness of mice. When scientists disabled these genes the result was similar the FosB experiment: cold-hearted mothers, empty-bellied pups. Both these genes influence how oxytocin, the “love hormone” behind caressing and nursing and other mothering behavior, is processed in the brain. When oxytocin doesn’t get to where it needs to go, the result is less nurture, more neglect. (Interestingly, in mice and humans, only the Peg1/Mest and Peg3 genes are imprinted and only the one inherited from the father is active. This means an afflicted mouse can blame her lack of mothering instinct on her dads. An attentive one can give him credit. )

“More Mommy genes!” the headlines raved. Mice and humans share many of the same genes, so these genes may influence women’s nurturing instincts, too. Perhaps we can test every wannabe mom to see if she has working copies of FosB, Peg1/ Mest, and Peg3. Then we’ll know who can soothe babies into submission and who thinks it’s a good idea to leave them to cry under the stars. Perhaps we can use genetic engineering to make us supermoms. No new parent would feel exasperated and hopeless again. Let’s make sure everyone has warm fuzzy mommy genes.

The scientists doing this research never claimed they found mommy genes. That sort of bravado would be embarrassing. Humans are obviously more complex than mice, and our behavior is more nuanced.

To say a gene makes a woman a good mother is a little like saying the carburetor is what makes a plane fly. Sure, the plane wouldn’t get off the ground without the device to blend air and fuel. But to credit the carburetor for flight? What about the wings, the pilot, the fuel? Or even the screws and the steel? And what about air around the plane, and the molecules in it? We can’t give all the credit (or blame) to one widget.

The same goes for “mommy genes.” Sure, genes influence how proteins are transcribed and neurons fire and signals are dispatched and hormones are received and processed, and so on. Every part of this infrastructure supports our nurturing behavior. We may be especially deficient if particular genes are defective or if they malfunction. There’s no doubt that researching these genes gives us valuable information about our nurturing behavior. But it’s likely that any one gene is just a widget in what makes us fly.

What’s a good mommy, anyway? That’s a debate beyond the realm of science. It’s slippery. When my newborn finally falls asleep in my arms, angelically, clutching my pinky, I feel like a good mommy again. It doesn’t require mommy genes.

It takes amazing grace.

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Can an infection have mind-control properties?

Posted in news, pregnancy by jenapincott on September 29, 2010

I try to be calm as the obstetrician draws my blood to test for toxoplasmosis.

Officially known as T. gondii, toxoplasmosis (or toxo) is a single-celled protozoa transmitted by exposure to cat excrement and by eating raw meat. We can also get it by gardening, eating unwashed fresh veggies and fruit, walking with bare feet on feces-rich soil.

My doctor tests all pregnant women for toxo, as do many doctors in Europe. Infection rates hover around 12 percent in the United States. In Brazil about 67 percent are infected (due to warm climate), in Hungary 59 percent, and in France about 45 percent (for the latter, blame all that steak tartare and pink lamb).

We’ve known for decades that toxo does weird things to the brain because rats infected with the parasite act a bit strange. By strange I mean they’re not only afraid of cat scents, they’re strangely aroused by them. And because they seek out cats, they’re often consumed, and in being consumed they infect the cats, completing toxo’s lifecycle. This is how the parasite perpetuates — by puppeteering. It manipulates rodents to sacrifice themselves to infect other cats and other rats, and so on.

Toxo may also invade and manipulate the human brain, which shares much of the same anatomy and neurotransmitters with rats — although mind control here is different (cats don’t usually eat humans, so there’s no evolutionary pressure on the parasite to tweak its effect on people). Paristologist Jaroslav Flegr of Charles University in Prague found that people with a latent infection tend to be more apprehensive, guilt-prone, self-doubting, and insecure. They have slower reaction times, especially if they also lack a certain blood protein, and three times as likely to get into traffic accidents due to impaired attention or reflexes. Infected women tend to be warmer-hearted, dutiful, moralistic, conforming, easy-going, persistent, and more outgoing and promiscuous. Infected men tend to be more jealous, rigid, slow-tempered, rule-flaunting, emotionally unstable, and impulsive.

Correlation is not causation, as scientists say when fascinating associations like this arise. But toxo may have an impact on personality and behavior because causes slight brain inflammation and alters its host’s levels of dopamine, the neurotransmitter associated with reward and anticipation (and also movement). The parasite does this by producing an enzyme called hydroxylase, which makes dopamine.

Dramatic as this sounds, most people are completely oblivious that toxo haunts their cells. Only pregnant women are commonly tested. And I’m one of them. Because I’m a hypochondriachal life-long cat owner who once worked on a farm, travels extensively, and doesn’t always scrub her veggies vigorously, I’m convinced I’ve been infected.

The nurse doesn’t think it’s an issue. “Not much happens if you’re positive,” she says, and shrugs. Her body language suggests it’s a silly test.

“Unless it’s a recent infection it doesn’t matter. We can tell by the antibodies if you’ve been infected in the last few months. If so, we give you antiparasitic drugs.”

Simple as that.

From a medical perspective, what she says is true. The risk to a fetus depends on the timing of infection and recent infection has the most disastrous consequences. If you happen to become infected with toxoplasmosis while pregnant, or soon before, the parasite or its toxins may cross over the placenta to infect your baby’s nervous system. Babies born to mothers infected in the first half of pregnancy often have shrunken or swollen brains and mental retardation. If infected in the second half, babies may not show symptoms at birth yet central nervous system problems may emerge years later. These babies are at a higher risk of developing schizophrenia — delusions, hallucinations — later in life, likely due to altered levels of dopamine triggered by the parasite.

The nice news is that if you’ve been infected for years before pregnancy you probably won’t pass toxo to your baby, nor will you likely have any obvious signs of infection (although cysts form in the brain). According to Dr. Flegr, only an active infection in the mom suggests a causal link between infection and her baby’s temperament. This is because your immune system usually keeps the parasite in check. But don’t think it’s completely asymptomatic.

In the past decade or so, studies have found that moms with dormant toxo infections have more sons (up to two boys for every girl), and those fetuses develop slightly more slowly than other babies. Perhaps there are other side effects that are undocumented.

Reading up on the science of prenatal infection I get reflective. Viruses, bacteria, and other parasites have always entered us — and some, such as our mitochondrial DNA (originally a bacterium), have become part of us and we can not live without them. Ancient viruses now exist deactivated or defanged in our DNA (in fact, genes from the placenta are thought to be a legacy of ancient viruses) Some viruses may be reactivated, like half-cured villains released from prison, and are thought to be a cause of cancer. Some invaders, initially dangerous, have converted to communalism, such as the thousands of good-guy varieties of healthy gut bacterial that make digestion possible. Strange but true: there are more bacterial than human genes in our bodies.

In a way, pregnancy has made me less fixed on the notion that my self is a singular identity over which I have total control. The fetus is me but not me, and she has changed me in ways I can’t yet fathom. The line between self and other is getting fuzzier.

But as philosophical as I get about self and other, me and microbe, my heart still races when I call the nurse to read my test results.

Negative for toxoplasmosis.

I’m relieved. Truth is, the only parasite I really don’t mind carrying is the baby.

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