Behave: The Biology of Humans at Our Best and Worst

by Robert M. Sapolsky

  * Not to mention the idea that adults should aspire to still be adolescent in many ways—to retain or regain adolescent tastes for novelty and sociality, adolescent levels of hair on the head and cellulite in the thighs, and adolescent refractory periods. Hunter-gatherers aren’t interested in “Look ten years younger!” They want to look like elders, so they can boss everyone around.

  * Not surprisingly, the peak of frontal cortical gray matter comes earlier in girls than in boys. Beyond that, what is most striking is the lack of major sex differences in the trajectory of adolescent brain development.

  * An interesting exception is that adolescents do not have particularly strong responses to disgusting stimuli, either on a subjective level or on the level of insular cortex activation.

  * With frontal regulation of emotions emerging later in males than females.

  * With the peak of sensation seeking coming and going earlier in females than in males.

  * What this doesn’t explain is why, for example, it’s males who leave among baboons and females who do among chimps, nor does it explain why novelty seeking varies among humans. That will be touched on obliquely in chapter 10.

  * Studies using this Cyberball paradigm typically have an important control group: The subject is in the same three-way game of virtual catch when they are told, “Oops, there is a computer glitch. We’ve lost contact with the other two players. Hang out in there while we fix this.” While things are being “fixed,” the other two players toss the ball. In other words, the person is left out, but because of technical problems, not for social reasons. And none of those brain regions activate. (Mind you, if it were me when in a less secure state of mind, it would certainly cross my mind that by the time that computer glitch was fixed, the other two would have already bonded and realized they were happier without me as part of the game and would continue to exclude me or, if they started throwing the ball back to me, would be doing so out of sheer condescension, thereby causing my mesolimbic dopamine system to instantly atrophy.)

  * The inventory requires the person to indicate the extent to which various statements tapping into social conformity apply to them—“Some people go along with their friends just to keep their friends happy,” “Some people say things they don’t really believe because they think it will make their friends respect them more,” and so on.

  * Some readers will recognize that those premotor neurons that start to imitate the movement being observed are “mirror neurons.” As will be seen in a later chapter, the mirror neuron system is fascinating, amid enormous amounts of hype.

  * I have not seen any studies that look at maturational sophistication about circumstances where harm to an object produces enormous emotional harm to individuals—for example, the destruction of religious relics. As will be covered in a later chapter, there is vast power to such symbolic objects.

  * How do you demonstrate object permanence in a preverbal infant? Show a child who is not yet at this stage a stuffie, which you then place in a box. For her, the stuffie no longer exists. Now take it out, and she thinks, “OMG, where’d that stuffie come from?” Her heart rate increases. Once the kid masters object permanence, pull the stuffie out of the box and (yawn) “Of course that’s where you put the stuffie”—no heart-rate increase. Even better: put the stuffie in a box and then pull something different (say, a ball) out of the box. Pre-object-permanence kid isn’t surprised—the stuffie stopped existing, and the ball just came into existence. Older kid with object permanence: “Wait, that stuffie turned into a ball!”—heart rate increases.

  * How would you test this? Two humans stand in front of a monkey, one blindfolded. A treat for the monkey is hidden somewhere. Blindfold is removed; monkey chooses which human goes to look for the treat. “Don’t choose the one who was blindfolded. They don’t know where the treat is,” thinks the ToM Master of the Universe monkey.

  * This “sensory motor resonance” might bring “mirror neurons” to mind. Chapter 14 examines what mirror neurons do (often in sharp contrast to what they’ve been speculated to do). The involvement of the PAG also brings to mind sociopaths, with their lack of capacity for empathy; as discussed in chapter 2, such individuals have atypically blunted pain perception.

  * The paper by Decety mentioned in the previous chapter had another interesting finding: For acts that harm people, the typical adult pattern is to advocate greater punishment for intentional acts. There is far less distinction made between intentional and unintentional when it comes to harm to objects. “Damn, I don’t care if he meant to Krazy Glue the fan belt or not—we have to buy a new one.”

  * “Greater good” for kids, as at any age, is in the eye of the beholder. In psychologist Robert Coles’s classic The Moral Life of Children (New York: Atlantic Monthly Press, 1986), he describes his fieldwork in the American South during desegregation, and how older children on both sides of the divide were willing to undergo sacrifice for the good of their ideological group.

  * I once received a lesson in kids’ private world of rule making from my then-four-year-old son. We had gone to a public bathroom together; we stood side by side at two urinals, and I finished a bit earlier than he did. “I wish we had finished at the same time,” he said. Why? “We get more points that way.”

  * The callous aggression speaks to another childhood predictor of adult sociopathy, namely abuse of animals.

  * I haven’t a clue whether that should apply to Floyd, the Depression-era bank robber (and murderer) who nonetheless became somewhat of a folk hero to the poor, and whose Oklahoma funeral was attended by somewhere between twenty thousand and forty thousand people.

  * A recent study adds an important twist to this story. There are the kids with problems with impulse control—“I’m absolutely going to hold out for two marshmallow”—who then instantly eat that first one. That profile is a statistical predictor of adult violent crime. In contrast, there are kids with steep time-discounting curves—“Wait fifteen minutes for two marshmallows when I can have one right now? What kind of fool waits fifteen minutes?” That is a predictor of adult property crime.

  * Bowlby, unlike most Freudians and behaviorists, actually had extensive experience with children, including children in the 1940s separated from their mothers—London children sent to the countryside during the Blitz, Central European Jewish children shipped to England in the Kindertransport rescues one step ahead of Hitler, and of course war orphans. BTW, what was Bowlby’s childhood like? He was the son of Sir Anthony Bowlby, the king’s own surgeon, and was raised by nannies.

  * Naturally, by now Bowlby’s offspring, the school of “attachment parenting,” is so established as to have generated endless misconceptions, fads, cults, lunatic fringes, and crazy-making senses of neurotic inadequacy or self-righteous superiority among parents. To open a can of worms a smidgen, there is no scientific support for concluding that a woman has irreparably damaged her child if she does not breast-feed, breast-feeds for less than the first decade of the child’s life, can’t successfully breast-feed her child within seconds after birth, or ever leaves the child alone for more than two seconds, let alone works outside of the house. And nothing about the science says that the same good effects of attachment can’t be provided by a man, a working single mother, two mommies, or two daddies.

  * The iconic nature of this study is such that I’ve heard psychologists sardonically reference Harlow, as in, “I had a pretty crappy childhood; my father was never around and my mother was a chicken-wire mom.”

  * Interestingly, Bowlby’s first published paper reported that thieves had an increased rate of extended maternal separation in childhood. Related to that, a 1994 study showed that individuals who suffered the combination of birth complications and maternal rejection at age one had a markedly increased likelihood of committing violent (but not nonviolent) crimes eighteen years later.

  * The
brutality of these studies helped spawn the animal-rights movement. I’ve been deeply conflicted about Harlow’s work since I was first moved to tears reading about it as a teenager. He was appallingly callous, readily admitted that he felt nothing for the monkeys, and did too many of the deprivation studies. But at the same time, the work helped, among other things, lay the groundwork for understanding the biology of how early-life loss predisposes toward adult depression. Given the prevailing wisdom at the time concerning child rearing and the perceived irrelevance of features of parenting that we now view as vital, the irony is that it was Harlow’s pioneering work that most clearly demonstrated the immorality of doing such research.

  * For example, early-childhood lead exposure—a strong correlate of living in a poor neighborhood—impairs brain development and predicts poor cognitive and emotional regulatory skills and increased incidence of criminality in adulthood.

  * What’s anhedonia like in a rat? Give a normal rat two water bottles to choose from, one with water, the other with water sweetened with sucrose. The rat prefers the sucrose water. But a stressed, anhedonic rat shows no preference. Same result for other pleasurable things.

  * Remarkably, exposure to multiple incidents of violence even accelerates the aging of children’s chromosomes.

  * I want to thank a really excellent undergrad, Dylan Alegria, who helped me tread water in this voluminous literature.

  * I thank another superb undergrad, Ali Maggioncalda, for help with this topic.

  * A shocking part of the story: Roma children were regularly abandoned at orphanages and left there until they were adolescents—and could work.

  * An irresistible irony: In the aftermath of the book’s publication, Harris received a major award from the august American Psychological Association, an award named in honor of . . . the man who, decades before, as chairman of the psychology department at Harvard, had thrown Harris out of the PhD program for her lack of potential.

  * All of these differences are typical in fathers as well but have been studied far more in mothers.

  * I’ve experienced a manifestation of such parenting in my decades of fieldwork in Kenya, where my nearest neighbors have been highly un-Westernized members of the Maasai tribe. Sometimes I’d run into someone I hadn’t seen in a while who had had a baby in the interim, and it took me years to get out of my ridiculous Western reflex—“A new baby! That’s wonderful! Mazel tov! What’s her name?” Awkward silence—you don’t give a baby a name (or perhaps aren’t willing to utter it) until she’s survived her first malarial rainy season and hungry dry season.

  * Which, as noted by Kusserow, included the largest percentage of fathers who were willing to be interviewed.

  * I once got a poignant reminder of just how permeating the consequences of lack of privilege are in my professional world. I was interviewing candidates for a position in my lab. In the process, I’d ask each person about how they handled interpersonal conflict, looking for people who promptly addressed a social tension, rather than letting it fester into passive-aggressiveness. I was interviewing a guy whose background was in Queens, rather than the Upper East Side. And when asked, instead of giving the Upper East Side answer I hoped for (“Yeah, I know how bad things get when you don’t communicate; I’d be pretty good at just asking the person to be considerate and please return my pipette when they borrow it”), I got the correct answer from Queens: “Nope, no problems there. I know that a lab is no place for fighting; you take it outside. You’ve got nothing to worry about with me.”

  * In contrast, newborns recognize but show no preference for their father’s voice.

  * This view held in most medical circles for many years afterward. For an example of how wrong that approach can be, see John Colapinto, As Nature Made Him: The Boy Who Was Raised as a Girl (New York: Harper Perennial, 2006).

  * Remarkably, studies have examined brains of transgender individuals, concentrating on brain regions that, on the average, differ in size between men and women. And consistently, regardless of the desired direction of the sex change and, in fact, regardless of whether the person had undergone a sex change yet, the dimorphic brain regions in transgender individuals resembled the sex of the person they had always felt themselves to be, not their “actual” sex. In other words, it’s not the case that transgender individuals think they’re a different gender than they actually are. It’s more like they got stuck with the bodies of a different sex from who they actually are.

  * Prenatal screening for CAH is now possible, and the fetal masculinization can be prevented to some extent with fetal hormone treatments. This has been framed by some clinicians as a means to increase the odds of a CAH female having a heterosexual orientation, something that has drawn the ire of bioethicists and the LGBTQ community.

  * Meanwhile, there is no consistent evidence that the extent of androgen exposure in the hours to weeks after birth predicts anything about subsequent behavior.

  * Why not “determines” instead of “influences”? Because the female’s body can convert one nutrient into another before passing it to the fetus.

  * Third-trimester malnutrition also alters aspects of physiology, so that the fetus has a lifelong increased risk of diabetes, obesity, and metabolic syndrome, something known as the “Dutch Hunger Winter effect.”

  * FYI, the gene that codes for the glucocorticoid receptor.

  * The next chapter discusses how this nongenetic but rather epigenetic transmission of traits multigenerationally resembles a long-discredited idea about acquired inheritance proposed by the eighteenth-century scientist Jean-Baptiste Lamarck.

  * Note: This does not mean that every neuron in the frontal cortex had the regulation of a thousand-odd genes changed. Instead, there are glial cells in addition to neurons, and the neurons are of a variety of types. So in reality the average number of changes within any given cell was probably far less than a thousand. Note about note: which doesn’t make any of this less interesting, just harder to study.

  * The strongest ideological criticisms of genetics have typically been leftist in flavor. Despite that, and to my surprise, the one study I know of that has examined the subject showed no Left/Right ideological differences in the tendency to attribute individual differences to genetics. Where they differ concerns what sorts of differences are attributed. Thus right-wing ideology is more associated with genetic interpretations for race or class differences, while left-wing ideology is more associative when it comes to sexual orientation.

  * My own personal experience with extreme essentialism: During 1976 and 1977 the New York City area was terrorized by the string of “Son of Sam” murders (I was home from college in Brooklyn during the summer of 1977 and can attest that the psychological impact of the murder spree was enormous). In August 1977 it ended with the arrest of David Berkowitz, a twenty-three-year-old petty criminal and arsonist who claimed that he killed under the command of a neighbor’s dog, said dog ostensibly being demonically possessed. A month later, back at college, the phone rang. My roommate answered and handed me the phone, looking a bit puzzled. “It’s your mother; she seems kind of excited.” “Hi, Mom, what’s new?” And in a euphoric, relieved, triumphant tone, she shouted: “David Berkowitz! He’s adopted. Adopted! HE’S NOT REALLY JEWISH!” Ironic ending department for my mother: The biological mother of Berkowitz, born Richard David Falco, was Jewish. As was his biological father, who was not Falco.

  * Terminology: A gene is “transcribed” when the RNA template of its DNA sequence is made, which is then used to generate the protein that it codes for.

  * Note that “junk” DNA may be junk or, more likely, DNA whose function hasn’t been discovered yet. There are reasons to go with the latter interpretation.

  * There are related stretches of noncoding DNA that are part of on/off switches called enhancers and operators. For our purposes, we’ll just use th
e term promoters.

  * Or to use other jargon in the field, when it is “activated” or “expressed”—I’ll use these terms interchangeably.