Behave: The Biology of Humans at Our Best and Worst

by Robert M. Sapolsky

  * How did Viljoen and Mandela come to meet secretly on that couch? It was catalyzed by a leading antiapartheid theologian . . . Viljoen’s twin brother Abraham. The two had been long estranged, although the general intervened on more than one occasion to prevent his brother from being assassinated by a right-wing death squad. The twins are teaching tools for chapter 8—same genes, radically opposite politics and worldviews. Same genes, and both charismatic leaders who devoted and risked their lives for what they viewed as a sacred cause.

  * See the actual event at www.youtube.com/watch?v=Ncwee9IAu8I. South Africa’s national anthem is now a hybrid of the two songs, with some Zulu, Sesotho, and English thrown in for good measure. While its existence is intensely moving, it must be hell on wheels to sing right, modulating all over the place.

  * I’m hugely grateful to Josh Greene and Owen Jones for closely vetting this chapter.

  * Namely keeping dangerous people far away from everyone else—just to get this one out of the way early in the chapter.

  * And one thing that I’m not going anywhere near is this New Age–y notion: “Of course we have free will. You can’t say that our behaviors are determined by a mechanistic universe, because the universe is indeterminate, because of quantum mechanics.” Argh. What anyone sensible who has thought about this will point out is that (a) the consequences of the subatomic indeterminacy of quantum mechanics (about which I understand zero) don’t ripple upward enough to influence behavior, and (b) if they did, the result wouldn’t be the freedom to will your behavior. It would be the utter randomization of behavior. In the words of philosopher/neuroscientist Sam Harris, a free will trasher, if quantum mechanics actually played a role in any of this, “Every thought and action would seem to merit the statement ‘I don’t know what came over me.’” Except you wouldn’t actually be able to make that statement, since you’d just be making gargly sounds because the muscles in your tongue would be doing all sorts of random things.

  * And just to show what a bleeding heart everyone thought Weyer was, his book was banned by both the Catholic Church and leading Reformation clergy.

  * I thank an excellent undergrad, Tom McFadden (now a superb biology teacher at my kids’ school!), for background research on M’Naghten.

  * I just love the use of the word “reform” in this context.

  * And I mean truly thinking that way, rather than backing into it because the alternative view would demand overwhelming changes in how society works.

  * I’m obviously confused by Gazzaniga’s stance, and I suspect his conclusions reflect his attempts to reconcile his worldview as a neuroscientist with his being a religious man, something he discusses in his memoir, Tales from Both Sides of the Brain: A Life in Neuroscience (New York: Ecco, 2016).

  * Many chapters ago I made reference to the “Son of Sam” murder spree in 1976 and the arrest of David Berkowitz. In his defense Berkowitz claimed that he was demonically possessed and had been commanded to murder—not by Satan, Hitler, Al Capone, or Genghis Khan but, instead, by . . . his neighbor’s dog. He was convicted and given six consecutive life sentences.

  * And also a very nice guy. Along with a Stanford colleague, law professor and bioethicist Hank Greely, I once got to debate against Morse and a colleague at a law school. It was both really fun, because Morse is insanely smart, and really terrifying, because he’s insanely smart.

  * Because cross-cultural psychiatry research shows that in individualist cultures, when depressed people talk to a friend for relief, they’re likely to talk about their problems, whereas in collectivist cultures they’re likely to ask about the friend’s problems.

  * Just to give a sense of how few baby steps we’ve taken, the maximal number of contributing variables identified in predicting depression is serotonin transporter status + childhood adversity status + adult social support status. That’s it, that’s about how far the literature has gotten. For frontal damage and antisocial violence, it’s neurological status of frontal cortex + D4 dopamine receptor subtype + ADHD status.

  * I thank an excellent student, Katrina Hui, for bringing my attention to Malleus Maleficarum.

  * I specify “in the West” because this is by no means a universal interpretation even today.

  * Cars may soon be entering discussions of moral decision making—when having to do one or the other, should a self-driving car smash itself into a wall, killing the passenger, in order to save five pedestrians? Most people think that is how such cars should be programmed but, predictably, would prefer that one that they used make the opposite choice. Perhaps more expensive models will work that way, while the hoi polloi have more utilitarian cars. Or maybe the car will decide, based on how frequently you clean it and change its oil.

  * The full list (figures in deaths per year, approximate): (1) World War II, 11 million; (2) An Lushan Rebellion, 4.5 million; (3) World War I, 3 million; (4) and (5) Taiping Rebellion and Tamerlane, each 2.8 million; (6) fall of the Ming dynasty, 2.5 million; (7) and (8) Mongol conquests and Rwandan genocide, each 2.4 million; (9) Russian Civil War, 1.8 million; (10) Russia’s sixteenth/seventeenth-century Time of Troubles, 1.5 million; (11) Mao-induced Chinese famines, 1.4 million.

  * This has always been the classic interpretation of Friedman’s idea. It’s quite possible, however, that people don’t go to war in those circumstances because they’re too busy going to the doctor for their adult-onset diabetes.

  * An exception is Lawrence Keeley of chapter 9, who argued that the net result of trade, with its inevitable disagreements, is more, rather than less, intergroup tension.

  * To be fair, Richard Nixon was raised as an Evangelical Quaker; they are not pacifists.

  * Although it is fascinating that over the last century, while Scandinavian countries developed their enlightened and far-reaching system of governmental support of people’s social needs, religiosity there plummeted dramatically; today only a small minority of Scandinavians are devoutly religious. So religiosity may not be as robust in the future as one would think, and as we saw in chapter 9, as secular institutions become better at caring for people’s needs, religiosity declines. Probably more important, this is a good demonstration that religion sure isn’t the only route for highly inclusive in-group prosociality.

  * Another limitation of the approach is that by definition there is self-selection for participants willing to entertain the possibility of détente with Thems. Moreover, participants often come from privileged socioeconomic backgrounds, limiting their ability to go and transform the masses afterward.

  * The British eventually crushed the rebellion, at the cost of approximately 150 British lives and 10,000 to 20,000 Kikuyu lives, and then handed over power to handpicked, über-Westernized Kenyans rather than Mau Mau guerrilla fighters; as a measure of how successful the Anglicized handoff was, more than fifty years later, black Kenyan judges still wear powdered wigs when presiding.

  * I thank a really excellent undergrad, Dawn Maxey, for her research assistance regarding TRCs and for the bulk of these insights.

  * And, it should be noted, there’s enormous controversy as to what percentage of kills are accidents, collateral damage to innocent bystanders; estimates range from 2 to 20 percent.

  * Yes, yes, I know this isn’t necessarily everyone’s list, but the point is the singularity, rather than the specifics of their acts.

  * Two who participated in the killings eventually committed suicide. One, Lieutenant Stephen Brooks, did so for unknown reasons while in Vietnam. The other, PFC Varnado Simpson, did so years later, after, among other things, seeing his ten-year-old son killed by a stray bullet fired by neighborhood teens. He said, “He died in my arms. And when I looked at him, his face was like the same face of the child that I had killed. And I said: This is the punishment for killing the people that I killed.” He suffered from severe PTSD, sequestered himself in
his home with windows shuttered for years, and succeeded on his third suicide attempt.

  * Thompson radioed fellow helicopter pilots to evacuate survivors to hospitals; Andreotta waded through the dead in the ditch to rescue a miraculously unharmed four-year-old. Thompson reported what he had seen to his commanding officers, who sent word of the events further up the chain. As a result, the senior officer who had commanded the search-and-destroy mission canceled the ones planned for subsequent days in neighboring villages and began the process of covering up what had occurred. Andreotta was dead within three weeks, killed in battle. Colburn and, even more so, Thompson, attempted to inform every military, governmental, and media source available about the events and played key roles in making the My Lai Massacre public. Representative Mendel Rivers, chairman of the House Armed Services Committee, attempted to block the prosecution of Calley and to have Thompson prosecuted instead as a traitor; Thompson testified against Calley at his trial and received death threats for years. It took thirty years for him and Colburn to be honored by the military for their actions. Thompson died in 2006, with Colburn at his bedside.

  * I thank two great undergrads, Elena Bridgers and Wyatt Hong, for help with the research throughout this section.

  * Which, among other things, is why the nervous system is so vulnerable to injury. Someone has a cardiac arrest. Their heart stops for a few minutes before it is shocked into beating again, and during those few minutes the entire body is deprived of blood, of oxygen and glucose. And at the end of those few minutes of “hypoxia-ischemia,” every cell in the body is miserable and queasy. Yet it is preferentially brain cells (and a consistent subset of them) that are now destined to die over the next few days.

  * For chemists, in other words, the distribution of charged ions inside and out balance each other.

  * Jargon: that little bit of “depolarization.”

  * Ironic footnote: Cajal was the chief exponent of the neuron doctrine. And the leading voice in favor of synctitiums? Golgi; the technique he invented showed that he was wrong. He apparently moped the entire way to Stockholm to receive his Nobel Prize in 1906—shared with Cajal. The two loathed each other, didn’t even speak. In his Nobel address, Cajal managed to muster the good manners to praise Golgi. Golgi, in his, attacked Cajal and the neuron doctrine. Jerk.

  * More with the keys in locks—the reuptake pumps have a shape that is complementary to the shape of the neurotransmitter, so that the latter is the only thing taken back up into the axon terminal.

  * What that also implies is that if a neuron is getting axonal projections to five thousand of its spines from a neurotransmitter A–releasing neuron and five thousand from a neurotransmitter B–releasing one, it expresses different receptors on those two populations of its spines.

  * This makes sense only after introducing an additional fact. Thanks to random, probabilistic hiccups in the ion channels now and then, neurons will occasionally have a random, spontaneous action potential from out of nowhere. So neuron A intentionally fires off ten action potentials, followed soon after by two random ones. That might make it hard to tell if neuron A meant to yell ten, eleven, or twelve times. By calibrating the circuit so that the inhibitory feedback signal shows up right after the tenth action potential, the two random ones afterward are prevented, and it is easier to tell what neuron A meant. The signal has been sharpened by damping the noise.

  * Thanks to the wisdom of Dale, we know that the same neurotransmitter(s) is coming out of every axon terminal of neuron C. In other words, the same neurotransmitter can be excitatory at some synapses and inhibitory at others. This is determined by what type of ion channel the receptor is coupled to in the dendritic spine.

  * Similar circuitry is also seen in the olfactory system, which has always puzzled me. What’s just to the side of the smell of an orange? A tangerine?

  * As an aside, there has been incredibly interesting work concerning emergent properties of the brain that helps explain how the different regions wire up in the developing brain in an optimal way that minimizes the amount (and thus “cost”) of axonal projections needed. For aficionados, the things the developing brain does bear some resemblance to some approaches used for the Traveling Salesman Problem.

  * An implication of these definitions is that the same molecule can serve as either a neurotransmitter or a hormone in different parts of the body. Also (minutia warning), sometimes hormones have “paracrine” effects, influencing cells in the gland in which they were secreted.

  * Just to make sure we have this sorted out, here’s a second example, namely the hypothalamic/pituitary/ovarian axis: the hypothalamus releases GnRH (gonadotropin-releasing hormone), which triggers the pituitary to release LH (luteinizing hormone), which triggers the ovaries to release estrogen.

  * And just to head off a potential misunderstanding at the pass, a zillionth of a percent of the cholesterol in your body is used for hormone synthesis, so changes in levels of cholesterol in the diet won’t impact the amount of such steroids made—the body synthesizes enough cholesterol on its own for steroid synthesis.

  * Actually typically more than one, but let’s not go there.

  * Naturally, the picture is more complicated than this, as is the case for most everything in this primer. Not all enzymes are made of proteins.

  * And as a clarification, there are millions of copies of a particular hormone molecule (e.g., insulin) in the circulation, all sharing that same shape.

  * Actually, I haven’t a clue how many atoms there are in the universe, but you’re required to say stuff like this.

  * The names of which I’m omitting, to avoid inundating the newcomer.

  * The central dogma of “information flows from DNA to RNA to protein” can be wrong. There are circumstances where RNA can determine the sequence of DNA. This has lots to do with how some viruses work but isn’t relevant to us. Another bit of revisionism, one that garnered two Nobel Prizes in 2006, is that a huge percentage of RNA does not then specify the construction of some protein. Instead it can target and destroy other sequences of RNA, a phenomenon known as “RNA interference.” Still other RNAs are created simply to render some segments of DNA itself “unreadable.”

  * There are other, rarer types of mutations. One class of them, for example, involves the codon coding for an amino acid called glutamine being repeated over and over in the gene, even dozens of times, producing what are called “polyglutamine expansion diseases,” the most famous being Huntington’s disease. They are extremely rare mutations, though.

  * As do a parent and child, while half siblings share 25 percent of their genes, as do grandparents and grandchildren, and so on.

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