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The Orchid and the Dandelion

Maria looked at the pregnancy test with disbelief. It couldn’t possibly be right. She was 17, barely three weeks into grade 11, and according to the small plastic rectangle in her hand, her life was about to change dramatically.

She went to her boyfriend’s apartment, resolving to break the news to him over dinner. She made pasta, overcooking the noodles and clumsily dropping a skillet of sauce onto the floor. Her hands trembled and her mind felt shrouded in thick, roiling mist. After 30 minutes of awkwardly puttering around the kitchen, she told him. Her declaration was terse: “I’m pregnant,” she said, the last syllable disintegrating into a long, terrified sob.

Tom, her boyfriend, was stunned but supportive. He’d moved away from home at 16 after a brief and bloody fistfight with his father, and lived on his own in a one-bedroom apartment above a pizzeria. Two years Maria’s senior, he’d finished high school with poor marks and, after a protracted stretch of unemployment, landed a job as a deliveryman for UPS. He told Maria he would stick by her and the baby, and though he wasn’t truly sure of it at the time, he meant it.

Maria gave birth to a baby boy midway through her second semester of grade 11. She named the child David. He was a happy baby. Maria fully intended on returning to school after weaning him, but somehow never got around to it. Instead, she got a job working nights as a waitress, and another as a cashier at 7–Eleven. She and Tom tried to arrange their schedules in such a way that one parent was always home. When this wasn’t possible, an elderly neighbour babysat for them. In exchange, Tom helped her out with a few simple chores. She became a surrogate grandparent to David, whose biological grandparents either didn’t know of his existence or wanted nothing to do with him.

Even with external support, David was often alone. He became self-sufficient at a young age, pouring his own cereal and dressing himself for kindergarten. His parents were kind and loving, but they maintained their social lives and enjoyed smoking pot, which they studiously avoided doing in front of him. As a result David was often left to his own devices, which suited him fine. He was happy entertaining himself and playing with the other children living in his apartment complex. The parents of these children, aware of David’s somewhat peculiar family situation, treated him warmly, feeding him and letting him sleep over and generally looking out for him.

When David was five years old, Maria got pregnant again. The ultrasound confirmed she was carrying twins. Maria panicked. She’d been excited about the idea of having another baby, but even one was sure to stretch her meagre budget to the breaking point. Two seemed utterly unfeasible. After talking things over with Tom, she decided to give one of the children up for adoption.

Maria named the girl she kept Melissa. She was a tiny baby, born about a month premature, and fussy. She cried often, especially at night. Maria and Tom’s sleep schedule became increasingly fragmented, Melissa’s incessant wailing denying them any more than an hour’s uninterrupted slumber. This, combined with the financial strain of raising another child, took its toll on Maria’s mood. She grew sulky and withdrawn, increasing her pot-smoking habit and occasionally yelling at her children, which she’d never done before. She still loved her kids, and cared for them to the best of her ability, but her efforts became increasingly threadbare as the conflicting demands of work and child-rearing wore away at her.

David took his role as big brother very seriously. He cared for Melissa as she grew, dressing her for school, making her meals, helping her with her homework, and doing his best to cheer her up. As a little girl, Melissa could be sweet and charming, and David could always make her smile. However, as she grew, she became more moody and distant. Her teacher reprimanded her frequently for her disruptive behaviour in class, and sent her home on two separate occasions: once for maliciously pouring a jar of paint over the carpet, and again for biting another student. At home, Melissa oscillated wildly between temper tantrums, pleading forgiveness, and silent, brooding withdrawal.

As David grew, he began to indulge in the rebellious acts typical of adolescence. He stayed out late, talked back to his parents, took up smoking for a brief period, and drank at the odd party where alcohol was available. But his grades remained fairly high, and his behaviour calmed down near the end of high school, when he became more focused on getting a proper postsecondary education. School didn’t excite him, but he understood its importance. Attending university seemed like an obligation he needed to fulfill; the consequences of not doing so far outweighed the benefits. He studied economics for two years, dropped out, and went to college instead, where he majored in computer science. He got a job shortly after receiving his diploma, and made a modest but happy life for himself.

While David mellowed, Melissa grew increasingly volatile. She partied incessantly, spent days on end away from home, and dated seedy men several years — and in one case an entire decade — older than her. Not content with the more common narcotic offerings of adolescence, she snorted cocaine and took dangerous amounts of ketamine. Sometimes she stayed up for days, or awoke in strange places without any idea of how she got there. On the surface, it seemed she delighted in making her parents worry, and appeared vindicated when she managed to make her mother cry. Her parents scolded her, grounded her, and pleaded with her, but nothing worked. When they told her their concerns, Melissa would scoff.

“Like you even give a shit,” she’d say. To Melissa, her parents’ neglect during her early years was unpardonable. They didn’t care about her then, she thought, so why should they all of a sudden care about her now? David she listened to, to a point, but when he would suggest she straighten up she would accuse him of being a shill for their mom and dad and storm off. He couldn’t reason with her and eventually stopped trying. Their relationship grew cold.

Overreacting

It’s hardly a surprise that siblings in the same family can have very different temperaments; anyone with a brother or sister could tell you that. Yet doesn’t it seem odd that two children raised by the same set of parents in the same household with roughly the same means can come to such radically different ends? It happens all the time, of course, but what exactly causes two children to react so differently to the same caregiving environment?

The answer has, in part, revealed itself through the studies we discussed in our previous chapter. Certain genes (DRD4, 5-HTT, MAO-A, etc.) can, depending on the allele (or version) one possesses, make a person more susceptible to adverse rearing conditions. In our scenario, David would be a low-reactive child, while Melissa would be high-reactive. Perhaps Melissa’s DNA contains the 7-repeat DRD4 allele, or one of the other problematic polymorphisms we’ve explored, making her more likely to act out in the face of her parents’ benign but persistent inattentiveness.

The question, then, is why do high-reactive traits exist at all? From an evolutionary standpoint, it seems unlikely that an increased disposition toward self-destructive behaviour would be selected for in the long run. Over generations, one would expect 7-repeat, s/s 5-HTT and their hypersensitive ilk to be outstripped by their more stalwart allelic brethren. Are these mutations simply too recent to have been selected out, or is our species too buttressed by its advanced technology and social structure for natural selection to take effect? Not likely. Many of the “problem” alleles we’ve discussed so far have counterparts throughout the animal kingdom, from primates all the way down to crustaceans, implying they’ve been around for a very, very long time. But what benefit could high-sensitivity provide?

To provide a possible answer, let’s check in on Melissa’s sister.

Separated shortly after birth, neither twin was aware of the other’s existence. As far as Marcy knew, she was the only child of Roger and Evelyn Davenport, a wealthy couple in their late thirties. Roger worked as an engineer and Evelyn as a travel agent. The Davenports were attentive and loving parents. They had tried for years to have biological children, but they couldn’t conceive on their own, and their repeated attempts at in vitro fertilization all failed. Though adopting was not exactly how they’d expected to have children, their love for Marcy knew no bounds, and they dedicated their lives — and their considerable means — to providing only the best for her.

Marcy went to a private school, took swimming lessons in the family pool, and had a playroom full of educational toys. Her parents hired skilled tutors to give her lessons in French, the piano, and gymnastics. Evelyn read to her from infancy, and Roger took her to every museum within five hours of their house. The family travelled often, and always took pains to experience and learn about the local culture of whatever country they visited. By the age of 10, Marcy was fluently bilingual, was proficient on three instruments, and had visited four continents.

Marcy loved school. She excelled in science, consistently handled mathematics at a grade level above her own, and devoured every book put in front of her. Every teacher she had considered her a natural student. Her grades were always the highest in class, and by the time she finished elementary school she’d amassed an impressive collection of scholastic awards.

In high school, she became an active member of student council, running in every student body election and winning almost every time. No one was surprised when she was elected valedictorian. Though affording school was not going to be a problem for her regardless — Roger and Evelyn had it covered — she was awarded generous scholarships that, supplemented by her savings from her part-time job, allowed her to pay her own way.

Marcy rocketed through university, got accepted to med school, and landed a residency less than two months after earning her degree. She seemed to thrive under pressure, a quality that, coupled with her fierce intelligence and love of challenging work, led her to specialize in neurosurgery. By 30, she was on track to becoming one of the most respected surgeons in her province.

She’d known she was adopted since she was old enough to start asking questions about it — and for a girl as smart as Marcy, this wasn’t very old at all — but it wasn’t until adulthood that she began pursuing her biological parents. It was during this process that she learned she had a twin sister. The news was exhilarating, though a little hurtful — part of her couldn’t help but wonder why her parents had given her up for adoption while her sister got to stay. In spite of these feelings, she sought out her sister, and was surprised at what she found.

Marcy had been told she was an identical twin, and though she knew their differing tastes and circumstances meant that they probably wouldn’t look as similar to one another as she might have imagined, she was nevertheless startled by Melissa’s appearance. She was 20 pounds thinner than Marcy, and dressed in leggings and a tacky jacket made of fake leather. Marcy’s silk blouse, though far from opulent, likely cost more than Melissa’s entire wardrobe.

Melissa clasped a cigarette between two fingers topped with artificial fingernails. Her face resembled Marcy’s but was prematurely lined. A child tugged at her leg and she patted his head distractedly as Marcy introduced herself. The conversation was polite but the two found they had little to talk about. Secretly, they both nursed doubts as to whether they were actually related. It just seemed so improbable that twins could turn out so differently.

Such stories take some of the wind out of genetic determinists’ sails. Marcy and Melissa are, genetically speaking, identical to one another. And though they were reared apart, they did spend the first eight and a half months of their existences (they were premature, remember) in an identical environment. During that time, they coexisted within a single uterus, absorbing the same nutrients and chemicals, reacting to the same stimuli, breathing in the same amniotic fluid. Sure, from that point on their paths diverged dramatically — Marcy was ushered into a life of privilege and intense intellectual nourishment, while Melissa remained in a home that was financially struggling and structurally laissez-faire — but neither were subjected to heinous abuse or dire poverty. Melissa had fewer advantages, but she never wanted for food, clothing, or shelter, and though she would probably scoff at the suggestion, she was loved.

Is it that simple, then? Do well-meaning but inattentive parents doom their children to a life of alcoholism and drug abuse? Hardly. Even within our brief example, we have David, who turned out well despite growing up in suboptimal early rearing conditions. We’ve already put forth one hypothesis for this discrepancy: David is a low-reactive child, while Melissa is high-reactive. Does this mean that Marcy, somehow, inherited a low-reactive gene not imbued to her sister?

Not necessarily. In fact, according to the theory of Biological Sensitivity to Context, it is probable that Marcy, like her sister, possesses high-reactive genes.

Biological Sensitivity to Context

When differences in reactivity among children first came to the attention of the scientific community, the predominant assumption was that high reactivity was a maladaptive trait — a genetic mutation that made those carrying it less likely to survive into adulthood than their unaffected peers. On first blush, high-reactive genes do appear to be something of a burden to those who possess them, a ball and chain shackled to their chromosomes, leaving their unfortunate heirs prey to whatever trauma the surrounding environment may decide to throw at them. We’ve presented this viewpoint once already, and explained its overarching flaw: these traits are old. In the face of hundreds of millions of years of evolutionary scrutiny, the 7-repeat DRD4 allele and its histrionic brethren should have been selected out eons ago, replaced by their staunch, stable, and unwavering counterparts. The fact that they haven’t suffered such an ignoble fate strongly suggests that they may provide some benefit to offset their potential costs, and a researcher named W. Thomas Boyce has compiled substantial evidence as to what that benefit might be.

Boyce is a professor of pediatrics at the University of British Columbia. In 2005, he released a paper explaining his theory of Biological Sensitivity to Context. Boyce was understandably skeptical of the notion that some genes were “worse” than others yet had somehow remained floating in the global gene pool all this time. He posited that high reactivity may be a double-edged sword, but can nevertheless be wielded effectively in the right circumstances. Increased sensitivity to one’s environment is not the same as increased sensitivity to pathogens, or exceptionally brittle bones, or haemophilia, or any other conditions that leave one in a vulnerable state without providing any tangible benefit. Rather, it is a difference in malleability. The behaviours of more reactive children — who, in Boyce’s theory, would be considered to have high Biological Sensitivity to Context (BSC) — are more easily sculpted by the surrounding environment than those of low-reactive children — those with low BSC. For Melissa, this meant succumbing to the more unfortunate aspects of her upbringing, and acting out against them in a short-sighted, self-destructive way. David, a low BSC child if ever there was one, took his home life in stride. Between the two of them, David seems to have the evolutionary edge.

But then there’s Marcy. Raised by exhaustingly attentive parents, ensconced in wealth and privilege, provided with every learning resource imaginable, she excelled at everything she put her mind to. For her, high BSC was a tremendous advantage, as it allowed her to make the most of the resources her privileged upbringing afforded her.

Boyce divides children into two poetically named categories: orchids and dandelions. Drawn from an old Swedish aphorism, the term “dandelion children” refers to hardy, rugged individuals with low BSC. Like the plants they are named for, they seem to thrive equally well in manicured lawns and cracks in the sidewalk. Orchid children, on the other hand, have high BSC. Like orchids, they flounder in substandard environments. But if the soil is pH balanced and nutrient rich, and the sun is shining just right, and the rain falls gentle but often, they grow into flowers of exceptional beauty.

Think back to some of the studies discussed in the previous chapter, namely those dealing with the DRD4 7-repeat allele. As you may recall, those with the 7-repeat allele — the “high-reactive” version of the gene — responded much more poorly to hardship than children with different, less reactive alleles. The precise nature of the response (depression, aggression, ADHD, etc.) and hardship (poverty, etc.) varied between studies, but the results were markedly similar.

The severity of these results swept aside a second finding. High-reactive children struggled in adverse living conditions while low-reactive children soldiered on; but in supportive conditions, where low-reactive children achieved about the same as their peers in “high risk” environments, high-reactive children thrived.

Monkey Business

Thirty miles from Washington, D.C., away from the crowds and the noise and the politics, the National Institute of Health’s Laboratory of Comparative Ethnology nestles into the bucolic Maryland countryside. Its location is well-chosen, for the LCE is not the stereotypical lab bedecked with stainless steel counters and finicky instruments awash in harsh fluorescent light. Most of the lab is outdoors, comprised of a swath of Appalachia demarcated by twin bands of electrified chain-link fence. Inside the fence live a colony of rhesus macaques, a primate not quite as closely related to us as chimpanzees or bonobos but that nevertheless shares about 95 percent of our DNA. The LCE is run by Dr. Stephen Suomi, a distinguished psychologist with a long history of working with macaques. Compared to some of his earlier studies, his present work is largely hands off. Much (but not all) of the research done at LCE is observational; aside from having food provided for them — in the form of a delightfully named substance called “monkey chow” — and living within borders defined by a two-tiered cyclone fence, the macaques at Suomi’s lab exist very much as they would in the wild. They feast and fight and fornicate, form alliances, and make power plays, all the while observing a strict and complex social hierarchy.

Macaque troops are matrilineal, stabilizing around a dominant and typically elderly female in groups of between 30 and 300 macaques, called troops. Females born into a troop stay there for life, their position rising and falling within the confines of that matrilineal line, until they themselves are, potentially, among the elder alpha females. Males, by contrast, exist on the fringes of macaque society. At adolescence (which, in macaques, occurs when the male is roughly four years old) they leave the clan of their birth — be it voluntarily or by force — and join roving gangs of similarly disenfranchised males. Life in a gang is a turbulent time for macaques, a Darwinian trial by fire where only the strongest, swiftest, and smartest escape the flames. Mortality rates in these gangs are exponentially higher than in any other facet of macaque society, and males are understandably eager to leave their shiftless existence and rejoin a troop in order to engage in the far more enjoyable pursuit of siring offspring.

Life among the macaques is relentlessly social. Size and strength undeniably help determine a macaque’s place in the hierarchy, but the truest predictor of success is a macaque’s ability to understand and interact with other macaques. In humans, we might call this emotional intelligence. A successful macaque knows exactly where she stands in the hierarchy. She knows which matriarch is the quickest to anger, and which is showing signs of weakness. She can recall without hesitation which macaques have her back in a fight, and which would just as soon bash her brains in with a rock. Macaque society thrums with political intrigue; to thrive, social graces are essential.

Sadly, when it comes to social graces, not all macaques are born equal. Over years of careful observation, Suomi noticed two recurring deviations in macaque behaviour. Macaques of the first deviation have what Suomi deemed to be neurotic personalities, and comprise roughly 20 percent of the total population. These macaques are reluctant to leave their mothers’ sides, and remain anxious and withdrawn well into adulthood. Anxious macaques socialize far less often than other macaques do, form fewer alliances, and swing dejectedly from the lower rungs of macaque society.

Macaques of the second deviation face similar yet opposing challenges. Suomi calls them bullies, and they comprise a smaller portion of the macaque population than do neurotic macaques: between 5 and 10 percent. This is a very good thing for macaque society at large, because, unlike the anxious subgroup, who meekly sidestep conflict and cause no harm, bully macaques are a nuisance to everyone and a danger to themselves. They get between high-ranking mothers and their children — a folly on par with stepping blindly onto a freeway at rush hour. They leap madly from treetop to treetop, taking risks at which more sensible macaques, despite being dextrous and acrobatically gifted, would balk. They challenge macaques twice their size to combat, and when they are inevitably beaten and shamed, they don’t learn their lesson; they attack again and again. Play fighting is a normal and healthy part of macaque development, but bullies have trouble grasping the “play” part — they bite and scratch and hit for real, alienating potential playmates and earning the ire of their mothers.

Anxious macaques and bullies have a lot in common. Both have trouble relating with other macaques in their troop. Both show signs of behavioural disorder, a fact neatly ascertained by the reaction of anxious and bully macaques to a “happy hour” test. For a one-hour period, macaques are given unrestricted access to a fruity beverage containing 9 percent alcohol. Well-adjusted macaques know their limits. They have between three and four drinks and call it quits. Anxious and bully macaques show no such moderation. They drink to excess, though each group goes about it in a different way. Anxious macaques drink more than they should, but they do so in a manner that suggests self-medication. They drink until they’re good and drunk. Bullies take it one step further. They are the frat boys of the animal kingdom, hitting the bottle as if it were an endurance contest. They drink until they are practically unconscious, their drunken bodies reeling and their blood alcohol content skyrocketing to dangerous levels.

But perhaps the most important connection between anxious and bully macaques is their origins. Both have genetic susceptibility to problematic behaviour, but genetic cause ends precisely there. In order to activate these behaviours, young macaques must experience them during childhood. Anxious macaques came from anxious mothers, and bully macaques from bully mothers. When these macaques grow, they adopt the same parenting flaws they themselves experienced as infants and impart them on a number of their children, lending the cycle of neuroses and violence an air of inevitability. But take the neurotic or aggressive macaque away from his troublesome upbringing and foster him to a nurturing, affectionate mother, and these adverse behaviours disappear.

The culprit, therefore, is poor parenting, though it is aided and abetted by certain high-reactive polymorphisms. If you’ve read this far, it shouldn’t surprise you that one of them goes by the name rh-5HTTLPR, the macaque equivalent of our notorious friend 5-HTT. As with 5-HTT, rh-5HTT has a long (l) and a short (s) allele; when you genotype bully macaques, guess which one you find? Consistently, the s allele makes an appearance, either paired with an l allele (l/s) or doubled up with anothers allele (s/s).

Genetically susceptible individuals, when raised in nurturing environments, are no more likely than genetically resistant individuals to succumb to their grim, ostensibly gene-predicted fates. Genes may be the trigger, but the environment is the finger that pulls it. And different environments choose very different targets, and so trigger very different outcomes. Suomi’s genetically vulnerable macaques may become bullies when raised by bullies, or suffer chronic anxiety when raised by anxious mothers, but when they are raised in supportive environments, they don’t just do okay, they flourish.

In a number of ways, high-reactive macaques fostered with love and affection actually exceed their low-reactive, similarly coddled peers. They consume less alcohol in happy hour tests. They become exceptionally caring mothers, their nervous energy channeled into a productive pursuit. They rise high in the social hierarchy, often becoming prize mates or matriarchs of top-ranking troops. And, on a molecular level, they process serotonin (the neurotransmitter responsible for modulating mood) roughly 10 percent more efficiently than l/l macaques, despite having the supposedly less efficient serotonin transporter gene.

Not all primates have an exact equivalent of the 5-HTT serotonin transporter gene. In fact, only two species do: macaques and humans. Macaques may not be our closest relatives, but we and they share another trait that every other primate lacks: versatility. Apes, chimps, and bonobos are fine-tuned to their environments; attempt to relocate them even in the most tightly controlled conditions and the results will be, at best, lukewarm. Macaques are a different story. Pluck a troop of macaques from their native home and drop them just about anywhere on Earth,[24] and they will not only survive, but prosper. Given adequate resources and sufficient means to avoid predators, their numbers will steadily increase until they reach the upper limits of sustainability.

On the Indian subcontinent, where indigenous macaques can be found, they dwell in jungles, hardwood forests, savannahs, the fringes of deserts, and the rocky outcrops of the Himalayan foothills. They have made their homes happily in rural Maryland, islands off the coast of Puerto Rico, the swamps of Louisiana, the high arid plains of Texas, and the San Fernando Valley. And while many of these macaque colonies are bolstered by human intervention, they are more than capable of surviving without us.

In the 1930s, a tour boat operator known as Colonel Tooey released a troop of rhesus macaques into the forests of Silver River State Park, Florida, in order to provide his river cruise business with a bit of exotic colour. Eighty years later, the descendants of these monkeys have become a significant part of the local ecosystem despite the repeated attempts of local farmers to wipe them out. These are not Great Apes in captivity, their environment meticulously regulated, their intergenerational survival hinging on the constant efforts of trained zoologists. These are monkeys that we’re actively trying to kill, but can’t. That’s truly impressive, because if there’s one thing human beings are good at, it’s killing our competition.

There exists a correlation between high-reactive serotonin transporter genes and primate adaptability. Does the former cause the latter? We cannot yet definitively say. Causation is a far harder relationship to prove than correlation. Yet it remains a tantalizing hypothesis. After all, our ability to adapt to new environments has been paramount to our success as a species; without it we would all remain nestled in the cradle of civilization, our numbers culled by severely limited resources and our ingenuity stunted by an absence of necessity. And studies have shown that high reactivity is only a liability when it and the surrounding environment clash. When they harmonize, it can prove to be a tremendous advantage. Could this two-tiered reactivity be the key to the success of us and our rhesus macaque cousins? Bold, high-reactive wagers hedged with a larger population of low-risk, moderate-yield alleles? We may never know for sure, but any new parents left wringing their hands as they await the results of their child’s genotype testing can relax. An s/s 5-HTT allele is not a death sentence. In fact, under the right environmental conditions, its presence could very well be an advantage.

The Two Faces of DRD4

Remember our Dutch friends, Bakermans-Kranenburg and Van IJzendoorn? They designed a study examining the effects of maternal sensitivity on externalizing behaviour. Researchers videotaped mothers as they interacted with their infants, noting both how much attention the mother paid to her baby and how the baby responded to that attention. A distracted, inattentive, or easily frustrated mother received a low maternal sensitivity score, and a crying, inconsolable, aggressive child ranked higher on the scale of externalizing behaviour. Bakermans-Kranenburg and Van IJzendoorn’s theory was that the presence of the 7-repeat DRD4 allele in children would make them more likely than average to act out when raised by low-sensitivity mothers.

The numbers agreed with them. Among children from low-sensitivity homes, those with the 7-repeat allele scored an average of 7 points higher on the Child Behavior Checklist externalizing behaviour scale than those without the 7-repeat. This is not surprising, as these children learned from an early age that, to ensure a response from their parents, they had to act out vigorously.

The results were more dramatic still when comparing 7-repeat children from low- and high-sensitivity homes. Those with low-sensitivity mothers scored over twice as high on the externalizing behaviour scale as those whose mothers were more cognizant of and attentive to their needs. That is a big jump. However, one comparison the researchers glossed over was between 7-repeat and non-7-repeat children in high-sensitivity homes. Among these two groups, the children with the 7-repeat allele (the high-sensitive version of the gene) scored over 4 points lower than their peers without the offending allele. In other words, the children with the risky, “problem” allele were actually better behaved than those with the stable, less reactive allele. Four points is a less significant discrepancy than 7 points, and not even close to the 10-point, 100 percent markup seen between 7-repeat children in low- and high-sensitivity homes. But it’s not peanuts, either.

The Dutch duo were not the only researchers to document this trend. Half a dozen different studies have reached similar conclusions. Dr. Kim-Cohen, a psychology professor from Yale University, found children with the less efficient “low reactive”[25] allele of the MAO-A gene — a polymorphism responsible for doubling incidents of externalizing behaviour when found in unsupportive households — accounted for below-average externalizing behaviour when possessed by children in supportive, nurturing homes. Again, the kids with the “trouble alleles” were the ones causing less trouble.

One of the more surprising findings came from Hungarian psychologist Dr. Judit Gervai. In many ways, Gervai’s study mirrored that of Van IJzendoorn and Bakermans-Kranenburg. Both looked at the prevalence of disorganized attachment as mediated by the DRD4 7-repeat allele. Both divided mothers into groups of low and high risk — for Van IJzendoorn and Bakermans-Kranenburg, this meant separating grieving mothers based on whether or not they were still struggling to resolve their loss. Gervai, meanwhile, grouped mothers based on whether or not they engaged in “disrupted maternal communication,” meaning they appeared disoriented, excessively needy, withdrawn, or childish in their behaviour toward their children. And both found that children’s genotypes dictated whether they would be susceptible or immune to their environments.

The only difference was which gene did which.

In Van IJzendoorn and Bakermans-Kranenburg’s study, as in every other experiment we’ve reviewed that incorporated the DRD4 gene, the 7-repeat allele increased children’s reactivity (or, as Boyce would put it, their Biological Sensitivity to Context). The 7-repeat children did as well or better than non-7-repeats in stable conditions, but when put under strain by poverty, neglect, parental depression, or any other hardship, they fared particularly poorly. Gervai reached the opposite conclusion. In her study, comprising 96 middle-class Hungarian families and 42 low-income American families, the 7-repeat allele acted as a moderating variable. Those who possessed it exhibited disorganized behaviour with roughly equal frequency regardless of whether or not their mothers engaged in disrupted maternal communication. Conversely, children without the 7-repeat allele were four times more likely to exhibit signs of disorganized attachment if raised by disruptive mothers than if raised by mothers who showed no signs of disruptive behaviour. When compared to a 7-repeat child, a non-7-repeat child was twice as likely to be disorganized if each were raised by a disruptive mother, but only half as likely if raised by a non-disruptive mother. The pattern is familiar; only the variables have been reversed.

Does this mean that either Gervai or Van IJzendoorn is wrong? Not necessarily. Their studies were similar, but they weren’t identical. By focusing on slightly different environmental causes — disrupted behaviour and communication in Gervai’s study versus more subtle responses to unresolved loss in Van IJzendoorn and Bakermans-Kranenburg’s — the two studies point to different gene-by-environment interactions. For children with the 7-repeat allele, mothers’ disrupted communication and childish behaviour did not seem to matter in predicting whether or not children were disorganized in their attachment. However, more subtle psychological responses to unresolved loss did make a difference. You could conclude, then, that parenting (particularly with high-reactive children) involves more than a specific set of behaviours, but rather a certain amount of psychological preparedness that likely could benefit from external sources of support like fathers, friends, and, if necessary, counsellors. Clearly, context matters more in some cases than in others.

Boyce’s Studies

Data from dozens of papers supported Boyce’s theory, but in order for Biological Sensitivity to Context to gain real traction, he needed to do some studies of his own. One of these measured the effects of biological sensitivity and environmental stressors on children’s susceptibility to respiratory illness.

Many human studies — including almost all of those we’ve discussed so far — measure children’s environmental stressors based on the disposition, behaviour, and socioeconomic situation of their parents. As parental bonds are the closest that children experience until at least adolescence, and as parents are the people with whom children spend most of their time, the quality of a child’s home life is a logical way to gauge his or her degree of exposure to environmental stressors. But it is not the only way. With more families finding it necessary to have both parents join the work force full-time, children are spending more of their early years in childcare facilities. Though parental influence remains important, Boyce thought a daycare centre could produce an environmental impact significant enough to affect a high-sensitive child.

Boyce measured the level of environmental stress in two ways. First, he disseminated questionnaires to four childcare facilities. The questionnaires contained descriptions of 20 minor stresses a child could experience during daycare: rejection by peers, change in drop-off or pick-up routine, toilet problems, etc. The events described were not deeply traumatic, but could conceivably embarrass or upset a child. Preschool teachers completed the forms every two weeks, noting the stresses, if any, experienced by each child in her care.

Boyce’s second measure was broader. Observing each of the four participating childcare centres, Boyce’s researchers noted the teacher-to-child ratio, staff turnover rate, proportion of full- and part-time teachers, teachers’ average education level, and overall quality as measured by the venerable Clifford Early Childhood Environment Rating Scale. These five criteria were tabulated and used to place each childcare facility on a continuum of environmental stress, with two centres in the low-stress field and two considered high-stress.

Next, Boyce needed to measure each child’s Biological Sensitivity to Context. As we’ve already mentioned, this is not as simple as genotyping each child and grouping them based on which allele of a given gene they have. Without any sort of genetic calibration, Boyce needed to assess each child’s sensitivity the old-fashioned way: through experimentation and empirical evidence.

The test was carefully designed. Boyce needed a series of activities enjoyable enough to engage 3- to 5-year-old children, but challenging enough to stimulate physiological stress responses, namely an increased heart rate and heightened blood pressure. He would then measure these stress responses and, based on his findings, declare a child to be high- or low-reactive.

The trouble with performing stress tests on children is keeping results consistent. Strange environments, the presence of a person the child finds frightening or unpleasant, or a tantrum on the ride over can act as emotional and biological white noise, weakening the signal the test picks up and garbling its results. Distortion is inevitable, but a good study keeps it to a minimum. Bearing this in mind, Boyce allowed the children to see, touch, and even operate the testing equipment a week before testing, in order to make them more familiar — and hence more comfortable — with the experiment while it was being performed. He held the tests in a quiet, secluded room within the childcare facility to keep the children focused but comfortable. The examiner was a woman the children had not met before; a familiar face may have been more comforting, but also would have come with its own collection of biases, both positive and negative. Children are usually more comfortable with women than men, and the examiner had experience working with young children.

The experiment’s content was as meticulously crafted as its setting. Participants completed seven activities that provided a physical, intellectual, and emotional challenge at a level that young children would find difficult but not daunting. The tasks were as follows: an interview, using building blocks to replicate a structure built by the examiner, remembering and reciting a series of numbers, a gestalt closure task,[26] solving a dispute between hypothetical classmates, identifying an object while blindfolded, and describing an emotional event. Throughout the procedure, children wore a blood-pressure cuff on their non-dominant arms that measured their heart rate and blood pressure.

Lastly, pediatric nurses and doctors checked the children each week for respiratory illnesses. Neither the doctors nor the nurses knew anything of the children’s sensitivity or the childcare centre’s level of environmental stressors. Each section of the experiment was performed in isolation from the others, and the three variables were only brought together after the data was tabulated and ready for analysis.

Boyce, W.T., Chesney, M., Alkon, A., Tschann, J.M., Adams, S., Chesterman, B., … and Wara, D. (1995). “Psychobiologic Reactivity to Stress and Childhood Respiratory Illnesses: Results of Two Prospective Studies.” Psychosomatic Medicine, 57(5), 411–422.

The findings confirmed Boyce’s suspicions. High-reactive children were 20 percent more likely to develop a respiratory illness if they attended one of the high-stress childcare facilities than if they attended a low-stress facility. Conversely, low-reactive children were 10 percent less likely to catch a respiratory illness if they attended a high-stress facility. Of the four groups, high-reactive children in low-stress daycare actually showed the lowest rate of respiratory illness, with an average of only four incidents per six-month period.

Boyce conducted several similar studies and scoured peer-reviewed journals for dozens more, amassing an impressive body of evidence to support his theory and fitting it eloquently within a broader evolutionary framework. Diversity has been the key to an organism’s survival almost since life began. Without it, even the most fearsome apex predator will inevitably be exterminated when some industrious microbe or parasite devises an effective way to attack them, or the environment becomes hostile, or a valued food supply dwindles. It’s the reason that sexual reproduction has been such a rousing success among just about every creature more complex than bacteria. If you don’t shuffle the deck, you may draw nothing but kings and queens at first, but eventually you’ll face a run of threes and twos that will almost certainly be your undoing.

Biological Sensitivity to Context is an extension of that premise. Varying degrees of sensitivity assure that the human species will be able to cope with a wide and ever-shifting range of environments. High-reactive children are humanity’s high-stakes bet. If the cards don’t fall their way, they lose big, but if they hit a hot streak, the payout is enormous. Low-reactive children, by contrast, are the human gene pool’s conservative investment, a kind of genetic GIC. The returns may not dazzle us, but the pool is, at least, safe. This diversified take on genetic investing works for the rhesus macaques, and it seems to be working for us, too.

But Boyce takes it farther. Prior to his theory, gene-by-environment interactions were considered to be much as we’ve described them thus far: a method of diversifying the gene pool to better assure our species’ survival. Boyce agrees with this concept, but does not consider it to be a purely passive phenomenon. Instead, he argues that Biological Sensitivity to Context is determined in part by the surrounding environment.

Tuning Our Reactivity

Think of environmental stress as a spectrum with a safe, well-adjusted, and financially stable upbringing at one end and an insecure, impoverished, and violent upbringing at the other. According to Boyce, children at either end of this spectrum are disproportionally likely to be high-reactive, while children in the middle are more likely to be low-reactive. Boyce believes that the environment does not simply predict a child’s chances of success, considering his or her genotype. Rather, it actually helps dictate the strategy that a child will adopt in order to cope with his or her surroundings, not just psychologically, but biologically.

But if Boyce is right, and BSC is determined by environmental factors early in life, why do children faced with severely adverse conditions become high-reactive? Every study we’ve reviewed shows that, under stressful conditions, high-reactive children perform worse physically, intellectually, and emotionally than their low-reactive peers. Shouldn’t an environmentally determined BSC account for this poor standing by making every child low-reactive unless they are born into a stable, nurturing family?

Consider Patricia Crittenden’s interpretation of attachment theory, the Dynamic Maturational Model. As you may recall, the crux of Crittenden’s theory is that children adopt seemingly self-destructive attachment behaviours because, during the first few years of their lives, they are the best strategies children have at their disposal. When a parent is consistently neglectful, a child cannot afford to waste energy by crying every time he or she is hungry or cold, since that behaviour has proven ineffective. Instead, the child becomes withdrawn, seeking comfort in his or her own self-sufficiency. When crying sometimes summons a caregiver and sometimes doesn’t, the child learns that the affection of his or her capricious protectors is fleeting, and as a result, he or she becomes clingy but not trusting. These behaviours often cause trouble for people down the road, straining their relationships with their family and peers, and hindering their ability to function effectively in a market society, where co-operation is paramount. But if in the child’s eyes the alternative is death, then such behaviours are, in the short term, advantageous. It doesn’t matter if the child isn’t actually likely to die (few parents are deliberately negligent enough to kill their children, and in many cases where they are Social Services will step in before they get the chance); the child is acting on basic evolutionary instincts, not rational thought, and so can only make decisions (though even calling them decisions is somewhat misleading) based on the lesson imparted to him or her.

Biological Sensitivity to Context operates in much the same way. When a given trait first rose to prominence, an adverse environment meant something very different than it does today. In modern times, few denizens of the first world face famine or drought on par with that experienced by our ancestors. We are at little risk of attack from vicious animals or rival tribes, and have developed our own protection from many of the diseases that once threatened to wipe our entire species from the face of the Earth. These dangers have shrunk or disappeared, but new ones have risen to take their place. Modern threats are complex and intuitional, and require a new set of defences that, from an evolutionary standpoint, we have not yet developed.

Here is the key difference. When we consider a trait maladaptive, we do so through the lens of an affluent and highly structured 21st-century society where the goal is to survive not just physically, but economically. People continue to die young, and probably always will, but making it to a procreationally viable age is no longer the feat of prowess and ingenuity it once was. Ten thousand years ago, it was all that mattered. Responding to a violent upbringing by becoming exceptionally aggressive, or mistrustful, or self-sufficient was, at the time, a fairly effective way to go about things. If times were hard, predators plentiful, and food scarce, then being the biggest and baddest primate on the block was the best way to assure that you survived long enough to pass on your genes. But now, when our body responds to similar cues of hardship, these ingrained survival traits become liabilities. Children grow up too aggressive to get along with others, too hyperactive to hold down a job, too anxious to make the social connections necessary to succeed in a service-based market economy. Our instincts have turned against us. Or, perhaps more accurately, the world has turned against our instincts.

Stressing Out

If BSC is environmentally determined, then why have so many studies linked reactivity to the presence of certain alleles? Boyce doesn’t discount the role genes play in determining BSC. Indeed, his studies have been among those that indicate their importance. He merely argues that the environment exerts an additional influence on our BSC on top of the effects of genes like DRD4 or 5-HTTLPR. It does so, says Boyce, by influencing the way our body responds to stress.

In both highly stressful and highly supportive environments, children become exceptionally attuned to stressful stimuli. Their heart rate rises, adrenaline floods their veins, and their minds become instantly alert, ready to respond to danger (or opportunity) in a fraction of a second. In a high-stress environment, it’s easy to see how this could have been an advantage. When danger continually looms in the form of a bear or a lion or an enemy tribe, quick reflexes and increased vigilance can be the difference between life and death. But for low-stress environments, the benefits of a heightened stress response system are less clear. Why would a child raised in a secure, nurturing, and supportive environment require a stress response system on par with a child for whom danger is a constant companion? The short answer is he wouldn’t, but Boyce offers a compelling theory as to why he got one anyway.

Do you remember the crash course in genetics we gave you back in chapter 3? If so, you’ll recall that genes aren’t the neatly ordered units of code they have often been described as in mainstream science articles. Rather, they are a conglomeration of nucleotide sequences interspersed with introns — commonly (and somewhat erroneously) called “junk DNA” — and spread across tens or hundreds of thousands of base pairs, and sometimes even multiple chromosomes. They overlap with other genes sharing the same nucleotide sequences, and can be reassembled in different ways at different times.

It should come as no surprise, then, that an organism built from such ostensibly chaotic instructions should possess some traits with unusual or unexpected connections. High BSC is one such trait. A number of studies have found a positive correlation between heightened stress response and a number of indicators of intelligence. On the surface, this seems strange. Stress, at sufficiently high levels, is supposed to elicit our most primitive instincts, forcing us into simple, atavistic responses like fight, flight, or freeze. We are more likely to associate intelligence with calm, rational, nuanced thinking, hardly the sort of thing one should engage in when being chased by a tiger or shot at by an advancing army. Yet deeper down, the link between the two traits becomes more apparent.

Researchers have found high-reactive children to be more reflective and more conscious of themselves and their environment. They are more capable of delaying gratification in pursuit of long-term goals, and have better self-control, than low-reactive children. One could see how these traits — particularly an awareness of oneself and one’s environment — could be useful at both ends of the environmental stress spectrum. To children in high-stress environments, it means an above-average ability to assess risk, spot danger, and remain vigilant in the face of a longstanding threat. To children without such dire concerns, the same trait can be put toward exploration, introspection, and invention, all hallmarks of high intelligence. Coming from the other direction, a 2006 study found that more intelligent, introspective individuals have trouble coping with stress. This is true not just of humans, either. Going back to Dr. Stephen Suomi’s Maryland compound, you may recall how members of the two major socially aberrant groups — the neurotics and the bullies — developed previously unseen advantages when raised by supportive mothers. The neurotics, genetically destined to fretful, low-status lives, became model parents, their anxiety honed into perception and forethought. The bullies, meanwhile, channeled their killer instincts into the political arena, allowing them the edge necessary to rise in the macaque ranks, while their more stable upbringings taught them the importance of the soft touch as well. In humans, as in macaques, intelligence and high-reactivity may be two sides of the same coin.

The Orchid-Fringed Garden

To turn speculation into data, Boyce conducted a pair of studies. The studies were similar in nature, both to each other and to experiments we’ve discussed in previous chapters. Boyce determined environmental stress through surveys and questionnaires, taking into account both demographic data (family income, mother’s level of education, etc.) and personal responses (whether there is much fighting at home, if mothers felt overwhelmed by the responsibilities of child-rearing, had the children been excluded by their peers or experienced a change in their routine, etc.). The studies each used slightly different measures, but the general category of questioning was the same.

To determine children’s Biological Sensitivity to Context, Boyce used the same stress test featured in his respiratory illness study reviewed earlier this chapter. Children performed a series of seven activities designed to stimulate their spatial and emotional reasoning while machines monitored their heart rate and blood pressure.

So why two tests? Given the similarities, it may seem redundant not to bundle them into a single experiment. Except Boyce differentiated between the two of them in one key way: focus. Boyce’s theory regarding BSC’s distribution can be graphically represented as a large U shape, with environmental stress represented by the x axis (left to right) and child reactivity by the y axis (up and down).

High-reactive children are largely distributed to the low- and high-stress ends of the environmental stress axis, represented by the two prongs of the U, while low-reactive children congregate in the middle of the axis, represented by the U’s round bottom. A number of studies we’ve reviewed have reflected this general trend: only the left, low-stress half of the U has been, in most cases, decidedly atrophied, failing to reach the same heights as the U’s right, high-stress half. Boyce argues that this discrepancy does not prove his theory wrong, but rather speaks to the imbalance of significantly low-stress and significantly high-stress environments in a normal population sample. To put it crudely, sore thumbs stick out. While high-stress environments are fairly common, exceptionally low-stress households are, unfortunately, fairly rare. Much more common are households in which there is a moderate — and completely normal — level of stress, as parents fret about bills, bemoan juice spilled on carpets or crayon scribbles on walls, or struggle to cram yet another doctor’s appointment or visit to the mechanic into their already hectic lives.

To counter this trend, Boyce ran his two studies with different scopes. The more broadly focused of the pair looked at three levels of environmental stress —low, medium, and high — and found the same lopsided U shape implied in the data from Bakermans-Kranenburg and Van IJzendoorn’s studies, and several others we’ve reviewed. Child reactivity was higher in low-stress environments than in middle-stress environments, but highest by far in high-stress environs. The other study, however, put aside high-stress environments entirely. It divided environmental stress into three more narrowly defined groups: very low stress, low stress, and moderate stress. Essentially, Boyce cut his original graph in half and focused solely on the left side of the U. He thought the shift in focus would invert the typical trend of higher-stress environments producing more high-reactive kids. And it did.

Boyce, W.T., and Ellis, B.J. (2005). “Biological Sensitivity to Context: I. An Evolutionary-Developmental Theory of the Origins and Functions of Stress Reactivity.” Development and Psychopathology, 17(2), 271–301.

Ellis, B.J., Essex, M.J., and Boyce, W.T. (2005). “Biological Sensitivity to Context: II. Empirical Explorations of an Evolutionary–Developmental Theory.” Development and Psychopathology, 17(02), 303–328.

Moving from very low-stress to low-stress environments, the drop-off in child reactivity is stark; from low-stress to moderate-stress, the difference is non-existent. Compare this to the almost linear increase in environmental stress from very-low to moderate groups, and the reason for all those lopsided U’s seems pretty clear. Highly supportive environments produce a disproportionate amount of high-reactive children, but only when those environments pass fairly rigorous standards of quality. In households like Marcy’s — the gifted child we talked about at the start of this chapter — high-reactivity is the BSC de jour. In less affluent homes, or households where parents don’t have the luxury of devoting every second of their lives to nurturing their children, low-reactivity becomes far more common. This trend continues until we reach a place where stress becomes intense and commonplace and child reactivity promptly rises to levels equalling those at the opposite, low-stress end of the spectrum.

Migration

Of course, there is another possible explanation for the prevalence of high BSC children in highly supportive and abusive homes, one that allows genes like DRD4 and 5-HTT a more prominent role. The increased number of high-reactive children in adverse environments may have come, in large part, from a gradual migration of genetically susceptible individuals to the fringes of the environmental adversity scale. For instance, think back to David and Melissa, the brother and sister introduced at the start of this chapter. Though raised in the same household, the two went on to live very different lives. David became a programmer for a fairly large company, earning a decent middle-class salary. His wife, whom he met in university and married shortly after graduation, worked in data processing, and the two of them made enough to provide a decent life for their children. Sometimes money was tight, but there was always food on the table, a roof over their heads, and enough left over to pay for field trips and piano lessons, and to take the odd vacation. Melissa, meanwhile, descended into a dark and gloomy cavern of adolescent debauchery from which she never fully emerged. She drank too much, partied too hard, tripped too intensely, and had her first child before she was emotionally or financially capable of shouldering that kind of responsibility.

David was a classic dandelion child, living comfortably and happily despite his less than idyllic home life. Melissa, on the other hand, was an orchid, and the care and climate of her childhood failed to meet her high standards. Their respective dispositions had an enormous impact on the outcome of their lives, and beyond that, the lives of their children. Not only are Melissa’s children at a socioeconomic disadvantage, living in near poverty and raised by an emotionally immature mother with a drug problem, they also have a 50 percent chance of inheriting the genes responsible for causing high biological sensitivity to context. Among her several children, those who inherit low BSC genes may overcome their adverse circumstances, while those with high BSC have the odds stacked much higher against them. Exposed and susceptible to poor rearing environments, high BSC children will often continue the cycle of poverty and addiction, passing it down to their own children, and so on.

Melissa and David aren’t the only people in this situation. Millions of families like theirs will show similar patterns, where dandelion children soldier on despite emotional and financial setbacks, and orchid children flounder. And since people typically meet, befriend, and marry people in their own socioeconomic level, the genes for low and high BSC may begin, over many generations, to separate. And the same is true on the opposite end of the spectrum. Marcy — Melissa’s prosperous twin sister, who was adopted by a wealthy family — is able to offer her children a life of privilege, opportunity, and unwavering support. Though all of them have a great shot at doing well and succeeding in any career they choose, the ones with high BSC will be able to truly maximize their potential, much as Marcy herself did.

Thus, just because a majority of high BSC children live in adverse circumstances doesn’t mean the environment directly caused high BSC; generations of genetic susceptibility may have simply attracted the more high-reactive individuals to the far ends of the environmental spectrum.

However, our reluctance to endorse every aspect of Boyce’s model doesn’t mean we reject his theory outright. Quite the opposite. His claim that biological sensitivity to context is an adaptive trait, as opposed to a maladaptive one, is well-documented. Nor do we entirely reject the notion that BSC is environmentally determined. We simply think that these influences might have a slightly different origin than Boyce describes.

We’ve known for some time that nature and nurture aren’t diametrically opposed, and that the enmity between genetic determinists and behaviourists was little more than political posturing and a case of tunnel vision. Not only are the two factors entwined through the gene by environment interactions we’ve discussed so far, they are actually linked by an intricate network of molecules capable of brokering exchanges between them. How they do so forms the crux of an important and exciting new science called epigenetics.