Science of Love, Sex, and Babies

Do You Live Less if Your Mom Was Stressed?

Posted in parenting, pregnancy, psychology, science, sex by jenapincott on August 12, 2011

Not long ago, a handful of scientists at the University of California at Irvine were curious about why some people live longer than others — even within groups that have similar ethnic and educational backgrounds, demographic and disease risk profiles, and are exposed to similar stressors in life.  At heart, they know the question is impossible to answer.  People are complex. The effects of life events on our genes—what we eat, what we breathe, who we love and how well we’re loved, and so on —are impossible to isolate.

But the scientists had a hunch that some of us had a bad start —beginning in the womb — because our mothers were highly stressed during pregnancy.   There’s an avalanche of evidence that women who are under extreme duress in pregnancy have kids who have shorter attention spans, lower IQ, memory deficiencies, and health problems.  

Could prenatal stress also set a baby’s life expectancy clock to tick faster?

One way to find out is to look at the genes of people whose mothers were extremely stressed during pregnancy. In each of our cells are DNA-protein complexes called telomeres, which cap the end of chromosomes.  Telomeres are like the plastic bit at the end of a shoelace to keep it from unraveling. Each time a cell divides, they become a little shorter. This makes telomeres something of a longevity marker. People with long tips at the end of their DNA strands tend to live longer than people who have short tips.  It doesn’t matter how long your shoelace is; what counts is the integrity of the cap.

In the UCI study, researchers recruited volunteers in their twenties. Some were selected because their mothers experienced a horrid event during pregnancy.  The scientists weren’t looking for the normal pregnancy stressors — work-life balance, weight gain, fretting about the baby’s health, and so on. They meant extreme stressors: a sudden divorce, a death in the family, a natural disaster, and physical or emotional abuse.

What they found is disturbing.

Compared to the control group (whose moms had a relatively stress-free pregnancy), people exposed to their moms’ extreme prenatal stress had significantly shorter telomeres.  By our mid-twenties, most of us lose about 60 base pairs of telomere length annually.  Not so of people who were exposed to extreme prenatal stress — they lose drastically more telomere length each year. The men had 178 fewer base pairs on average (equivalent to 3.5 additional years of aging).  Women had a shocking 295 base-pair deficit  (5 years of accelerated aging). It seems that a mother’s prenatal stress hits her daughter harder than her son.

How does this happen?  During pregnancy, stress may alter blood flow, oxygen, and glucose metabolism between mother and baby. High levels of the stress hormone cortisol from the mother flood the placental barrier. Excess cortisol may also slow down in the production of telomerase, an enzyme that acts as a repair kit for telomeres. Telomerase adds telomeric DNA to shortened telomeres. It regenerates our cells and tissues.  Like a fountain of youth, telomerase gives back what time takes away.

So what if you’re on a telomerase-less trajectory?

Here’s the big relief:  Your clock doesn’t have to keep ticking so quickly, even if it has been set that way before birth. There’s strong evidence that lifestyle changes can amp up telomerase production. One study found that stress management, counseling, and a healthy diet are associated with higher telomerase activity.  Another found that meditation turns up the telomerase dial.  

In the research community there’s much interest in the idea that, by maintaining our telomeres, gene therapy might someday reverse or prevent aging if started early enough.  Is it possible? As a measure to conceal the abuses of youth, teens could freebase on telomerase. 

Oh, the ways to stress out Mom.

 

 *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. 

 

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.

Do Fish and Coconuts Reverse Prenatal Stress?

Posted in news, parenting, pregnancy, psychology, science by jenapincott on July 22, 2011

Is it any coincidence that the most laidback people I’ve ever met hail from Brazil, land of fish and coconuts?  

The mellowness of Brazilians came to mind when I read a study on prenatal stress to be published next month in the International Journal of Neurodevelopmental Medicine. The researchers, including lead author Carlos Galduróz, are biologists at  Universidade Federal de São Paulo (in Brazil).

It’s been long known that significant prenatal stress — characterized by a blitz of  the stress hormone cortisol — harms a fetus. Prenatal stress results in an increased risk of premature birth and low birthweight.  In humans, it’s linked with anxiety, attention deficit disorder, impaired memory, low test scores in childhood, and depressive behavior in adulthood.  Rats whose mothers are exposed to extreme stressors are likelier to have impaired motor skills and are slower to learn.

Intriguingly, there’s evidence that the mother’s diet might offset some of these disadvantages.  A baby whose stressed-out mom ate “special” foods during pregnancy and lactation may fare better than one whose equally stressed -out mom ate a normal diet. 

Galduróz and his colleagues were curious to know if the composition of fat in a prenatal diet might make the difference. So, during the equivalent of second and third trimester, they subjected some of the rats in their study to extreme stress — restraint and bright lights for forty-finve minutes, three times daily.  Some of these pregnant rats were fed a diet high in omega-3 fatty acids, the kind found in salmon, sardines, and other fish. Others were fed a diet high in saturated fatty acid from coconut milk. A third group ate normal rat chow.

The results?

As expected, babies of stressed-out moms had lower birth weights.  The surprise came three weeks later:  Babies whose moms ate fish oil or coconut fat diets during pregnancy and lactation gained weight quickly. So quickly, in fact, that they became the same weight as the babies whose moms weren’t stressed during pregnancy.  In other words, fish and coconut fats reversed the impact of low birthweight, a potentially dangerous effect of prental stress.

That’s not all.

Babies exposed to prenatal stress were more active (restless) than other pups if their moms were on a regular or coconut-oil diet.  Interestingly, if a stressed-out mother was on a fish oil diet, her pups were not more restless than those of pups with non-stressed moms.

In an earlier study by the same authors, adult rats whose moms ate a coconut fat or fish oil-based diet released fewer stress hormones (a reduced corticosteroid response) than rats whose moms ate a normal diet.

Many studies have shown that fish oil, omega-3s, modulate mood by reducing the stress response. This has been shown in rat studies, and also in many (but not all) human studies.  Is it possible that when a mother consumes food containing omega-3s, her babies are less agitated? Are they happier?  Of course, rodents express anxiety, neuroticism, and depression differently from human babies.  But the healing effect of nutrients is fascinating.  Do stressed-out moms on fish-and-coconut diets have happier, healthier babies than their equally stressed peers who don’t eat as well?

For the real possibility that  fish and coconut oil have prenatal physical and psychological perks, I link to a favorite recipe here. It’s for moqueca, a stew made of fish and coconut fats, from Bahia, the Coconut Coast of Brazil.

 *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. 

 

 

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?

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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Why redheads feel more pain

Posted in news by jenapincott on April 26, 2009

angry-girl-showing-middle-fingerRedheads may be hotheads, but they get colder quicker. 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. Red hair is red due to excess production of the molecule pheomelanin. While we brunettes produce more eumelanin (dark brown pigment), redheads produce an excess of pheomelanin. Too much of this yellow-red pigment is the result of mutations in the MC1R.3 gene. Redheads have two copies of this variant allele, one from each parent.

So what does the “redhead gene” have to do with sensitivity? University of Louisville anesthesiologist Edwin Liem suspects that when both copies of the MC!R.3 have mutations, which is the case for redheads, the melanocortin 4 receptor is faulty, inefficient, and/or unable to be transported to the surface of cells. This receptor happens to modulate sensations of cold and pain. Another explanation is that the mutation in the MC1R gene, the same one that produces too much pheomelanin, 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 began to feel chilling pain at around 6C (43F), unlike the volunteers with dark hair, who did not really begin to ache until the temperature approached freezing. In another study, by Liem et al., women with various hair color types were exposed to electric shock. Turns out, the redheads needed about 20 percent more anesthetic to put down 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, a study found that 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.

POLL: Would you test him for the “cheating gene”?

Posted in Polls and Surveys by jenapincott on September 29, 2008

Imagine there’s a genetic test that could reveal your man’s chances of being a cheater — or, at least, a difficult long-term companion. Would you make him take it?  Turns out we’re one step closer to having the option.

Can your genes make you cheat? is one question posed in BLONDES.  To answer, I mention recent studies on the monogamous prairie vole and the role of vasopressin, a hormone associated with monogamy.  Prairie voles are much more monogamous than their cousins, the montane vole, and the difference might boil down to different variants of vasopressin receptor genes in the two species. (Vasopressin receptors exist in regions of the brain related to trust, reward, and bonding, including the ventral tegmental area or VTA.)  Scientists have  since speculated that men, too, might vary in their vasopressin receptor genes….and that might make all the difference between faithful guys and cheating rats.

Now there’s more concrete evidence that men do indeed differ in their vasopressin receptor genes, and that that a single genetic variation affects their love lives.  Hasse Wallum , a medical epidemiologist at the Karolinska Institute, found that men who had one or two copies of allele RS3 334, a variant of a vasopressin receptor gene, were more likely to have relationship crises than men who lacked the variant. The wives of guys with the variant cited more relationship problems than did women married to men without the variant.  Interestingly, studies have also found that autistic men are more likely to have copies of this wayward gene variant.

Although the study stresses that men with RS3 334 alleles aren’t guaranteed to be romantic duds and deadends — after all,  the effects are modest, other genes may be involved, and cultural factors have their sway — but it inspires the imagination.  What do you do if your man has the “cheating” gene, putting your relationship at greater risk of strife and infidelity?  Do you still date him – or do you dump him?  Would you even want to know? 

So, do you test him?

(Thoughts welcome in comment box below.)