Science of Love, Sex, and Babies

Do Beautiful Babies Become the Most Beautiful Adults?

Posted in pregnancy, psychology, science by jenapincott on August 18, 2011

The Gerber baby, then and now

Forgive me, I believe my one-year-old is the cutest baby ever. Yes, yes, mothers are biased about their own children.  As I detail in my new book, certain reward circuits “light up” in parental brains only when looking at their own offspring.  But objectively — objectively! — my daughter is adorable.

The little one has “Gerber baby” features:  a bulbous forehead, big eyes, luscious cheeks and thighs (and curls). Babies with these qualities are rated as cuter than those with sunken foreheads, small eyes, and large or long chins.  Adults smile and gaze longer at them. Attractive infants are perceived to be more sociable, easier to care for, and more competent than their homely peers. They inhibit aggression in adult men. They receive more nurture.

Our baby thrills to the attention, and my husband and I have started to worry that being cute might not lead to anything good.  I have a theory that ugly ducklings and tomboys grow up to have richer inner lives.  I don’t want a princess.

We want to know:  Do the cutest babies turn out to be the most attractive adults?

Conveniently, a recent study by psychologists Gordon Gallup Jr, Marissa Hamilton, and their colleagues addresses this very question. (I love these whimsical studies; they’re motivated by genuine curiosity.) The presumption is that physical attractiveness remains stable over time.  This has been proven in childhood onward:  attractive ten-year-olds are likelier to be attractive adults.  (Another study found that adult attractiveness can be predicted as early as age five).  But until now no study had tracked attractiveness from infancy.

It’s interesting, how the psychologists went about it.   They sifted through high school yearbooks and found forty graduating seniors who featured photos of themselves as infants. Then they asked several hundred college students to rate the the individuals — in infancy and in adulthood — for attractiveness.

The upshot?

There was no correlation between attractiveness in infancy and (young) adulthood. Some ugly ducklings turned into swans, some baby swans become ugly ducks.  Some gawky, awkward babies remained that way into their senior year of high school.  And some beautiful babies kept their glow through the years. This was true of males and females alike.  Cuteness — or homeliness — in infancy does not predict future attractiveness.

The study included an interesting side finding:  While the raters were likely to agree about which infants were attractive, they often disagreed about which eighteen-year-olds made the cut. Why? The gold standard of baby beauty — the forehead, the eyes, the thighs — is universal. These preferences are hard-wired in us to elicit care and protection, while the perception of adult beauty is tempered by culture.

Cute babies are universal positives.  In this light, it’s OK that mine gets attention now.  The future will be much less predictable.

 

 *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, Do Chocolate Lovers Have Sweeter Babies?: The Surprising Science of Pregnancy. 

 

Do Flame Retardants Make Us Dimmer?

Posted in parenting, pregnancy, psychology, science by jenapincott on July 6, 2011

When I was in the second trimester of pregnancy, my husband and I bought a new king-sized mattress.  Like all cotton mattresses sold in the U.S., ours had been treated with a flame retardant containing polybrominated diphenyl ethers (PBDEs) and/or organohalogen compounds (OHCs). Flame retardants are also in pillows, car and airplane seats, drapes, rugs, and insulation. They’re in electronic equipment, like TVs, and in the dust on top of TVs.  They’re in air and soil and breast milk.  Almost all humans have flame retardants flowing through their veins.

             Around the same time I got my new mattress (on which I tossed and turned in third trimester), two surprising studies were published on the effects of flame retardants on fetuses and young children.

Study #1

A group of researchers at the University of Gronigden in the Netherlands recruited nearly 70 pregnant women in third trimester, taking samples of their blood and measuring it for PBDEs and OHCs. Five years later, the children were given standardized developmental tests for motor skills (balance and coordination), cognition (intelligence, spatial skills, control, verbal memory, and attention), and behavior.

The result:  PBDEs were correlated with worse performance on fine motor tasks and a shortened attention span.  Strikingly, they were also linked with better coordination and visual perception, as well as better (more placid?) behavior.  OHCs, meanwhile, were correlated with worse fine motor skills. Oddly, these kids had better visual perception.

 Study #2

 Researchers at Columbia University tested for PBDEs in the cord blood of nearly 400 women who delivered their babies at a New York City hospital.  These children were given mental and motor development tests in infancy and, later, at four-to-six years. These tests measure memory, problem solving, habituation, language, mathematical concept formation, and object constancy.  They also assess ability to manipulate hands and fingers and control and coordinate their movements.

 The result:  At both age intervals, children who had higher cord blood concentrations of PBDEs scored significantly lower on tests of mental (lower IQ) and motor development.  This was particularly evident at age two for motor skills and age four for IQ (nearly 8 points lower for certain PBDEs).

 

            Are flame retardants slowing us down? Correlation is not causation, but there’s a real risk that they do — and researchers have some ideas about how these chemicals have a toxic effects on the brain. OHCs (for instance) have been found to decrease a fetus’s production of thyroid hormone by interfering with thyroid receptors. This leads to an increase in thyroid stimulating hormone (TSH). Brain development in the fetus relies on the precise timing and quantity of thyroid hormone; too much or too little causes developmental delays. High prenatal exposure to TSH is associated with lower IQs – 4 points less on average.  During critical developmental periods, PBDEs and OHCs may also have a toxic effect on neurons in the hippocampus, the memory region of the brain, by reducing the number of neurotrasnmitter receptors.

            Infants and toddlers have what researchers call a high “body burden” of flame retardants. Household dust, which floor-playing infants and toddlers encounter constantly, accounts for 80-93 percent of postnatal PBDE exposure, followed by breast milk (however, the benefits of nursing appear to outweigh this drawback; breastfed babies score higher on neurodevelopmental tests). 

            A disturbing fact is that American kids have levels of PCBEs that are 10 to 1,000 times higher than their peers in Europe or Asia. We produce 1.2 billion pounds of the stuff annually. (Interestingly, the Scandivanian study, whose subjects had lower levels of prenatal exposure, found no IQ deficit while the U.S. study did.) Consider our nation’s problems:  attention deficit disorder, placidity, lower standardized test scores in reading and math.

Are flame retardants making kids dimmer?

            The question fires up the imagination.  Should pregnant women be advised to avoid, say, dusting and buying new mattresses in the same way we avoid emptying the litter box (to avoid toxoplasmosis)? Are the perceived gains in visual perception real, and, if so, why, and do they come at the expense of other abilities? Are urban kids at a higher risk  than average? Are there naturally flame-retardant materials that we can use in lieu of chemicals?   More research, especially on American kids, is warranted.

            After all, the nightmare scenarios can keep an expectant mom up all night, tossing and turning on her nonflammable mattress.

 

 * If you wish, 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?

 

 

 

Where Do Demanding, Unweanable Babies Come From?

Posted in news, parenting, pregnancy, psychology, science by jenapincott on May 24, 2011

A season ago, when my daughter reached the six-month mark, her pediatrician told us to introduce her to a new food every few days and see what she likes. It wasn’t time to wean her, but soon it will be, and supplementation should help the transition. So I lovingly shopped for organic fruits and vegetables: apples, bananas, avocados, peas, and so on. I presented them passively — as items for her to experiment withon her placemat — and actively, by making mmmms, playing airplane, and swallowing the goop and showing her my tongue.

Three months later, we’ve made astonishingly little progress on the solids front. At best, the infant deigns to nibble delicately on peas and lentils. She’ll squish the bits of mango and avocado on her plate and drop them on the floor. She’ll taste a food then whip her head to the other side and bat away the spoon. She wrinkles her nose.

All she really wants to do is nurse. Baby loves to nurse. She cries and cries in the wee hours of the morning because she wants to nurse. She is tall and heavy for her age.

Who’s to blame (at least in part) for her unweanable stubbornness?

Her dad. 

It’s not only convenient to blame the father for babies who won’t give up nursing, It’s scientific.  There’s evidence.    

Here’s how it works, according to a new study Bernard Crespi, an evolutionary biologist at Simon Fraser University.  How much and how long a baby nurses depends in part on her genes. The genes she inherits from her father have an ulterior motive.  Paternal genes want the baby to extract as much as possible from the mother.

Paternal genes are thought to influence:

  • suckling strength  (so the baby extracts as much milk as she can)
  • tongue size (a larger tongue is a better suction pump)
  • crying  (for maternal attention and food)
  • appetite and speed of eating
  • duration of breastfeeding before weaning
  • night-time suckling (results in suppression of periods, which helps delay future pregnancies/siblings)

The genes that influence these behaviors are active only when they come from the dad. This is called genetic imprinting — when only the genes from one parent are expressed. Dad’s genes strongly affect the intensity of infant behavior.  Only a tiny percentage of human genes are imprinted. 

Dad’s genes are greedy for a good reason. From a biological perspective he has nothing to lose by making sure this particular offspring who carries his genes demands a lot of her mom — including suckling often, crying a lot, and taking a long time to wean. This behavior may be essential to a child’s survival in a setting in which resources are limited. “Weaning” genes have been shaped this way under evolutionary pressure in a premonogamous era.

Mom’s genes, meanwhile, are more moderate.  They want the child to survive but dial back the feed controls. They’d prefer for a baby to self-feed and start solids sooner. Mom’s genes push moderation to save resources (time and energy) for her other (or future) offspring. When paternal genes are disabled and maternal genes are active, babies have Prader-Willi syndrome, a condition that manifests as inability to latch and suckle effectively, complacency, and lack of crying or other solicitation for food.  These infants wean early because they never really nurse. They fail to thrive.

Demanding, unweanable infants come from dads. At a minimum, paternal genes play a real role in their aggressive eating, crying, and nursing behaviors.  

Now that they’re outed, perhaps guilty fathers should be the ones to work the night shift and scrape  food off the floor?

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?