Something Interesting While Stuck at Home

[shiny!]

If you want to learn some mind-blowing stuff, or maybe you're just bored, check out neuroscientist, neuroendocrinologist, primatologist, author and generally interesting guy, Robert Sapolsky.

Say WHAT??

Give it 10 or 15 minutes and see if you're not hooked:

[Mega]

Re: Something Interesting While Stuck at Home

Thought you were going to find me a date.............

[shiny!]

Re: Something Interesting While Stuck at Home

He'll explain why you can't get a date ;-)

[shiny!]

Re: Something Interesting While Stuck at Home

(Highlighted the line below in red because for many today, this perfectly describes life under Covid-19)

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How to Relieve Stress

Robert M. Sapolsky explains why stress can become a chronic problem—and how we can reduce the toll it takes on our lives.

By Robert M. Sapolsky | March 22, 2012

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This month, we feature videos of a Greater Good presentation by Robert M. Sapolsky, one the country’s foremost experts on stress. In this excerpt from his talk, the best-selling author and Stanford University professor explains the difference between bad stress and good stress, and how we can manage the effects of chronic stress on our lives.

In 1900, what do you think were the leading causes of death in this country?

If you were 20 to 40 years old and a woman, the single riskiest thing you could do was try to give birth. TB, Pneumonia, influenza killed a lot of other people. But few people under the age of 100 die of the flu anymore. Relatively few women die in childbirth. Instead, we die of these utterly bizarre diseases that have never existed before on the planet in any sort of numbers—diseases like heart disease, cancer, adult-onset diabetes, and Alzheimer’s.

Now, some of this has to do with nuts and bolts biology. But some of it has to do with issues that nobody ever had to think about before in medicine—totally bizarre questions like, “What’s your psychological makeup?” or “What’s your social status?” or “How do people with your social status get treated in your society?”

And this one: “Why is it that when we’re feeling unloved, we eat more starch?” Figure that out, and you’ve cured half the cases of diabetes in this country
Indeed, when you look at the diseases that do us in, they are predominantly diseases that can be caused, or made worse, by stress. As a result, most of us in this room will have the profound Westernized luxury of dropping dead someday of a stress-related disease. That’s why it’s so urgent that we understand stress—and how to better manage it.

How stress kills

Do you remember “homeostasis,” a term I guarantee you heard in ninth grade biology? Homeostasis is having an ideal body temperature, an ideal level of glucose in the bloodstream, an ideal everything. That’s being in homeostatic balance.

A stressor is anything in the outside world that knocks you out of homeostatic balance. If you’re some zebra and a lion has ripped your stomach open and your innards are dragging in the dust and you still need to get out of there—well, that counts as being out of homeostatic balance.

So to reestablish that balance, you secrete adrenaline and other hormones. You mobilize energy and you deliver it where it’s needed, you shut off the inessentials like the sex drive and digestion, you enhance immune defenses, and you think more clearly. You’re facing a short-term physical crisis, and the stress response is what you do with your body. For 99 percent of the species on this planet, stress is three minutes of screaming terror in the savannah, after which either it’s over with or you’re over with. That’s all you need to know about the subject if you’re a zebra or a lion.

If you’re a human, though, you’ve got to expand the definition of a stressor in a very critical way. If you’re running from a lion, your blood pressure is 180 over 120. But you’re not suffering from high blood pressure—you’re saving your life. Have this same thing happen when you’re stuck in traffic, and you’re not saving your life. Instead you are suffering from stress-induced hypertension.

We humans turn on the stress response with memories, with emotions, with thoughts, and the whole punch line is: That’s not what it evolved for. Do it regularly enough, and you’re going to damage your cardiovascular system. Increased blood flow hammers on the walls of your blood vessels, causing inflammation. Fat and glucose and cholesterol glom on and begin to clog your arteries. That’s bad news. You are more at risk for chronic fatigue, sleep disruption, muscle atrophy, and probably most importantly, adult-onset diabetes, this once obscure disease that’s just on the edge of being the number one killer in this country.

Chronic stress also does bad things to the nervous system. Stress kills neurons in the part of the brain called the hippocampus and weakens the cables between neurons, so they can’t talk to each other. This impairs the formation and retrieval of long-term memory. The opposite thing happens in the amygdala, which is where we see fear in a brain scanner. In the hippocampus, stress causes stuff to shrivel up. But stress feeds the amygdala. It actually gets bigger. Chronic stress creates a hyper-reactive, hysterical amygdala, and this tells us tons about what stress has to do with anxiety disorders.

Another domain: the mesolimbic dopamine system. Dopamine is a neurotransmitter that is about reward and pleasure. Cocaine works on the dopamine system. All the euphorians do. What are the effects of chronic stress on this part of the brain? Those pathways get depleted of dopamine, and this takes away your ability to feel pleasure. So if stress depletes your dopamine, what have you just set yourself up for? Major depression.

What about the frontal cortex? It’s the most human part of the brain; we’ve proportionally got more of it than any other species does. And what does the frontal cortex do? It does gratification postponement, self-discipline, long-term planning, emotional regulation. It’s the last part of the brain to fully mature—that doesn’t happen until you’re 25 years old, which explains a lot about the freshmen year of college.

This has a very interesting implication. If this is the last part of the brain to fully develop, by definition, then, it is the part of the brain least constrained by genes and most sculpted by experience. What does chronic stress do to the frontal cortex? Atrophy of neurons, disconnecting circuits. As a result, you make the most idiotic decisions, which are going to haunt you for the rest of your life, and yet you think they’re brilliant at the time. That’s another effect of chronic stress: Your judgment goes down the tubes.

How to manage stress

We’ve just gone on a quick tour of all the things that can go wrong from chronic stress. If you study the subject for a living, it’s amazing to you that anybody is still alive, that we haven’t just collapsed into puddles of stress-related disease.

Despite that, most of us do decent jobs at coping, and a subset of us is spectacular at coping. And thus from day one, stress researchers have wondered why some bodies and some psyches deal better with stress than others. In making sense of individual differences, what we’re essentially asking is, “What is it that makes psychological stress stressful”? And a huge elegant literature by now has shown precisely what the building blocks are.

The literature is built on experiments like this one: You have a lab rat in a cage, and every now and then, you give it a shock. Nothing major, but nonetheless, the rat’s blood pressure goes up and so do stress hormone levels. Up goes the risk of an ulcer. You are giving this rat a stress-related disease.
Now, in the second cage, there’s another rat. Every time the first rat gets a shock, so does the second. Same intensity, same duration, both of their bodies are being thrown out of homeostatic balance to exactly the same extent.

But there’s a critical difference: Every time the second rat gets a shock, it can go over to the other side of its cage, where there’s another rat that it can bite the crap out of. And you know what? This guy’s not going to get an ulcer, because he has an outlet for his frustrations. He has a hobby.

There are other stress experiments that involve torturing rats, which suggest ways for humans to manage stress. We can give the rat a warning 10 seconds before each shock, and we find it doesn’t get an ulcer. That tells us that you are less vulnerable to a stress-related disease if you get predictive information.
Another experiment: If we give the rat a lever to press, and that rat thinks he’s in control of the shocks, that helps—a sense of control decreases the stress response.

Yet another experiment tells us it helps to have friends: If a rat getting shocks has a friend it likes in the cage, and they are able to groom each other, the rat doesn’t get the ulcer. So social affiliation helps control stress.

In short, you are more likely to get a stress response—more likely to subjectively feel stressed, more likely to get a stress-related disease—if you feel like you have no outlets for what’s going on, no control, no predictability, you interpret things as getting worse, and if you have nobody’s shoulder to cry on.

Okay, these are very powerful observations. They’re helpful. But please don’t assume that if you get as much control in your life and as much predictive information in your life as possible, you will be protected from stress. To understand why, let me share some of the subtleties of this field.

Look at the rat that got a warning. Timing is everything. He didn’t get an ulcer when he got a 10-second warning. But if the warning light goes on one second before the shock occurs, it has no positive effect whatsoever, because there isn’t time for the rat to adjust anything. Or suppose, instead, the warning light comes two minutes before. That will make the ulcers worse, because the rat is sitting there, ulcerating away, thinking, “Here it comes, here it comes, here it comes.” When it comes to predictive information, there’s only a narrow window where it works.

When does a sense of control work? When you’re dealing with a mild to moderate stressor, because in those circumstances you know how much worse it could have been and can imagine, rightly or wrongly, that you had control over that improvement. But if it’s a major disastrous stressor, the last thing you want is an inflated sense of control, because that sets you up to think that the disaster is all your fault. In the case of a major disaster, we tend to minimize people’s sense of control—by saying, for example, “It wouldn’t have mattered if you had gotten him to the doctor a month ago, it wouldn’t have made a difference.” And one of the worst things we do, societally, is attribute more control to victims: “Well, what’s she going to expect if she dresses that way?” or “Well, what are they going to expect if they choose not to assimilate?”

In short, a sense of control is protective for mild to moderate stressors, but it’s a disaster for major ones. In that domain, the most humane thing you can do is foster denial and rationalization rather than a sense of responsibility.

When is stress good?

Just as not all stress management techniques work, not all stress is bad. In fact, we love stress. We pay good money for it in a scary movie or on a roller coaster ride. We love stress when it’s the right amount of stress.

When is it optimal? When it’s only moderately stressful, at the most. And good stress is transient—it’s not for nothing that you don’t have roller coaster rides going for three weeks! The stress also has to be happening in a context that feels safe overall. Moderately stressful at most, transient, safe—what does that define?
© John Goode
That defines stimulation. That defines what play is. What is play about?

It’s when a higher rank dog says to a lower ranking dog: “I am willing to suspend our dominance relations right now and allow all sorts of unpredictable interactions. To show how much I’m doing that, I’m going to give you access to my throat or my genitals, and we’re just having a great time here playing.” In play, you feel safe, and as a result, you are willing to give up some control and predictability. We say, “Surprise me!” That’s good stress.

There’s another lesson we can learn from dogs and other hierarchical mammals, like baboons: Social rank can cause stress, especially where rankings are unstable and people are jockeying for position. But social rank is not as important as social context. What patterns of social affiliation do you have? How often do you groom, how often does somebody groom you? How often do you sit in contact and play with kids?

What’s clear by now is if you have a choice between being a high-ranking baboon or a socially affiliated one, the latter is definitely the one that is going to lead to a healthier, longer life. That’s the baboon we want to be—not the one with power, but the one with friends, neighbors, and family.

[thriftyandboringinohio]

Re: Something Interesting While Stuck at Home

What a great article shiny!.
Some time ago you brought us a different Sapolsky essay. As a result I bought his book Behave. I put it down about a third of the way through when it got heavily technical about brain physiology. I going to pick it back up and finish it. It's clear Sapolsky has some pretty good insights into how and why we think and act and react, and how we can adjust all those to be happier.

[shiny!]

Re: Something Interesting While Stuck at Home

What a great article shiny!.
Some time ago you brought us a different Sapolsky essay. As a result I bought his book Behave. I put it down about a third of the way through when it got heavily technical about brain physiology. I going to pick it back up and finish it. It's clear Sapolsky has some pretty good insights into how and why we think and act and react, and how we can adjust all those to be happier.

Glad you enjoy Robert Sapolsky as much as I do. If Behave is too dense of a read, you might try watching his Stanford lecture series on Human Behavioral Biology. Behave covers much if not most of the Stanford material. There's a trick to not getting bogged down in the technicalities: If it gets too dense, don't worry about it because the next lecture will begin with a summation of the most important take-aways from the previous lecture. The lectures tend to be technical until the break. After the break they're about applying the technical stuff to real-world examples, which is a lot easier to follow.

Sapolsky is one of those gifted scientists who is also a great teacher. I watched him explain a very technical, hard-to-grasp concept. Then he explained it in a different way. Then again in yet another different way. Then a fourth time in another different way. By the fourth repetition I got it. He was teaching to an audience with different experiential backgrounds and different learning styles. That's the mark of a great teacher.

If you want a really fun read that's also quite thoughtful and beautifully written, check out A Primate's Memoir. It's his coming-of-age, "fish out of water" story about his early research years in Kenya.

I came across Sapolsky quite by serendipity. For the last few years I've been struggling with mood and cognitive issues caused (I believe) by social isolation (no family), PTSD, traumatic grief and early childhood head injuries. There's a beautiful large zoo near my house. I few years ago I bought an annual pass so that I might have a pleasant place to walk on nice days. Figured it would do my brain and body good to get out, walk around and socialize.

I've never been "into" primates. In fact, I had always found the ones in movies to be repulsive. Their ugly grins gave me the creeps. I've since learned that these aren't grins but fear grimaces. Handlers with whips and shock prods are just off screen, threatening the poor things to make them grimace so that audiences will see the monkey "smile." My intuition had been telling me that there was something disgusting going on, but it wasn't the monkey, it was the abuse.

Anyway, one day I happened to walk past the Olive (savannah) Baboons and saw a tiny black infant. His mother had turned away just as he tried to nurse. In frustration, the little guy had a temper tantrum. He stood straight up on his hind legs; shaking his hands in the air he SCREAMED in his mother's face. "EEE! EEE! EEE!"

It was hilarious but also scary. I waited with bated breath for Mom to slap him across the face because that's what my mother would have done. But she didn't. She paused for a long moment, gazing at him like a stone buddha, then reached out and gathered him into her arms for a big hug.

I was just gobsmacked. All I could think was, THAT is how you raise a baby! THAT is how you treat a child!

I've been observing this little family ever since, 6-8 hours a day, 2-3 days a week when weather allows, watching some of the best parenting you'll ever find. I started reading everything I could find about baboons. I read that a baboon troop had lost all its aggressive males to TB and become peaceful as a result, and that they had remained that way for many years. I was looking for more info on this when I found a clip of the guy who had made the discovery: Robert Sapolsky. It was his Forest troop that this happened to.

So there I was, bopping around on Youtube looking for more stuff about baboons by some Sapolsky guy when I found a fascinating interview with Joe Rogan. Turned out that this Sapolsky guy not only knows baboons, he's also spent his career studying the effects of stress on the brain, of which I'm a poster child! After that interview I had to hear more, and that's when I found the Stanford lectures.

I've learned how to communicate respectfully to baboons. They're so familier with me now that most of them come to greet me when I show up. They've become like family to me- only their much nicer than the family I grew up with. Their keeper even let me name one of the babies.

The alpha male and his oldest son take turns sitting near me, just to hang out. This is quite an honor because they generally despise humans. Baboons look down on us because they value courteous manners. To them, our manners are just awful. They think we're savages. Judging from the way that most of the human visitors scream at them, mock their appearance and interrupt their family interactions to demand their attention, they're quite right.

Here's Derek, Mama and Cheeky, and their children Anubis, Imani and Zane:

[shiny!]

Re: Something Interesting While Stuck at Home

Peace Among Primates

Anyone who says peace is not part of human nature knows too little about primates, including ourselves.

By Robert M. Sapolsky | September 1, 2007

It used to be thought that humans were the only savagely violent primate. “We are the only species that kills its own,” narrators intoned portentously in nature films several decades ago. That view fell by the wayside in the 1960s as it became clear that some other primates kill their fellows aplenty. Males kill; females kill. Some use their toolmaking skills to fashion bigger and better cudgels. Other primates even engage in what can only be called warfare—organized, proactive group violence directed at other populations.

Yet as field studies of primates expanded, what became most striking was the variation in social practices across species. Yes, some primate species have lives filled with violence, frequent and varied. But life among others is filled with communitarianism, egalitarianism, and cooperative child rearing.

© Theo Allofs/Corbis
© Peter Glinter/Getty Images

Patterns emerged. In less aggressive species, such as gibbons or marmosets, groups tend to live in lush rain forests where food is plentiful and life is easy. Females and males tend to be the same size, and the males lack secondary sexual markers such as long, sharp canines or garish coloring. Couples mate for life, and males help substantially with child care. In violent species, such as baboons and rhesus monkeys, the opposite conditions prevail.

The most disquieting fact about the violent species was the apparent inevitability of their behavior. Certain species seemed simply to be the way they were, fixed products of the interplay of evolution and ecology, and that was that.

And although human males might not be inflexibly polygamous or outfitted with bright red butts and six-inch canines designed for tooth-to-tooth combat, it was clear that our species had at least as much in common with the violent primates as with the gentle ones. “In their nature” thus became “in our nature.” This was the humans-as-killer-apes theory popularized by the writer Robert Ardrey, according to which humans have as much chance of becoming intrinsically peaceful as they have of growing prehensile tails.

That view always had little more scientific rigor than a Planet of the Apes movie, but it took a great deal of field research to figure out just what should supplant it. After decades’ more work, the picture has become quite interesting.

Some primate species, it turns out, are indeed simply violent or peaceful, with their behavior driven by their social structures and ecological settings. More importantly, however, some primate species can make peace despite violent traits that seem built into their natures. The challenge now is to figure out under what conditions that can happen, and whether humans can manage the trick ourselves.

Old primates and new tricks

To an overwhelming extent, the age-old “nature versus nurture” debate is silly. The action of genes is completely intertwined with the environment in which they function; in a sense, it is pointless to even discuss what gene X does, and we should consider instead only what gene X does in environment Y. Nonetheless, if one had to predict the behavior of some organism on the basis of only one fact, one might still want to know whether the most useful fact would be about genetics or about the environment.

Two classic studies have shown that primates are somewhat independent from their “natures.” In the early 1970s, a highly respected primatologist named Hans Kummer was working in a region of Ethiopia containing two species of baboons with markedly different social systems. Savanna baboons live in large troops, with plenty of adult females and males. Hamadryas baboons, in contrast, have a more complex and quite different multilevel society. When confronted with a threatening male, the females of the two species react differently: A hamadryas baboon placates the male by approaching him, whereas a savanna baboon can only run away if she wants to avoid injury.

Kummer conducted a simple experiment, trapping an adult female savanna baboon and releasing her into a hamadryas troop and trapping an adult female hamadryas and releasing her into a savanna troop. The females who were dropped in among a different species initially carried out their species-typical behavior, a major faux pas in the new neighborhood. But gradually, they absorbed the new rules. How long did this learning take? About an hour. In other words, millennia of genetic differences separating the two species, a lifetime of experience with a crucial social rule for each female—and a miniscule amount of time to reverse course completely.

The second experiment was set up by Frans de Waal of Emory University and his student Denise Johanowicz in the early 1990s, working with two macaque monkey species. By any human standards, male rhesus macaques are unappealing animals. Their hierarchies are rigid, those at the top seize a disproportionate share of the spoils, they enforce this inequity with ferocious aggression, and they rarely reconcile after fights. In contrast, male stump tail macaques, which share almost all of their genes with their rhesus macaque cousins, display much less aggression, looser hierarchies, more egalitarianism, and more behaviors that promote group cohesion.

Working with captive primates, de Waal and Johanowicz created a mixed-sex social group of juvenile macaques, combining rhesus and stump tails together. Remarkably, instead of the rhesus macaques bullying the stump tails, over the course of a few months the rhesus males adopted the stump tails’ social style, eventually even matching the stump tails’ high rates of reconciliatory behavior. It so happens, moreover, that stump tails and rhesus macaques use different gestures when reconciling. The rhesus macaques in the study did not start using the stump tails’ reconciliatory gestures, but rather increased the incidence of their own species-typical gestures. In other words, they were not merely imitating the stump tails’ behavior; they were incorporating the concept of frequent reconciliation into their own social practices. Finally, when the newly warm-and-fuzzy rhesus macaques were returned to a larger, all-rhesus group, their new behavioral style persisted.

This is nothing short of extraordinary. But it brings up one further question: When those rhesus macaques were transferred back into the all-rhesus world, did they spread their insights and behaviors to the others? Alas, they did not—at least not within the relatively short time they were studied. For that, we need to move on to a final case.

Left behind

In the early 1980s, “Forest Troop,” a group of savanna baboons I had been studying—virtually living with—for years, was going about its business in a national park in Kenya when a neighboring baboon group had a stroke of luck: Its territory encompassed a tourist lodge that expanded its operations and, consequently, so did the amount of food tossed into its garbage dump. Baboons are omnivorous, and this “Garbage Dump Troop” was delighted to feast on leftover drumsticks, half-eaten hamburgers, remnants of chocolate cake, and anything else that wound up there. Soon they had shifted to sleeping in the trees immediately above the pit, descending each morning just in time for the day’s dumping of garbage. (They soon got quite obese from the rich diet and lack of exercise, but that is another story.)

The development produced nearly as dramatic a shift in the social behavior of Forest Troop. Each morning, approximately half of its adult males would infiltrate Garbage Dump Troop’s territory, descending on the pit in time for the day’s dumping and battling the resident males for access to the garbage. The particular Forest Troop males who did this shared two traits: They were especially combative (which was necessary to get the food away from the other baboons), and they were not very interested in socializing (the raids took place early in the morning, during the hours when the bulk of a savanna baboon’s daily communal grooming occurs).

Soon afterward, tuberculosis, a disease that moves with devastating speed and severity in nonhuman primates, broke out in Garbage Dump Troop. Over the next year, most of its members died, as did all of the males from Forest Troop who had foraged at the dump. (Considerable sleuthing ultimately revealed that the disease had come from tainted meat in the garbage dump. There was little animal-to-animal transmission of the tuberculosis, and so the disease did not spread in Forest Troop beyond the garbage eaters.) The results were that Forest Troop was left with males who were less aggressive and more social than average, and the troop now had double its previous female-to-male ratio.

The social consequences of these changes were dramatic. There remained a hierarchy among the Forest Troop males, but it was far looser than before. Compared with other, more typical savanna baboon groups, high-ranking males rarely harassed subordinates and occasionally even relinquished contested resources to them. Aggression was less frequent, particularly against third parties. And rates of affiliative behaviors, such as males and females grooming each other or sitting together, soared. There were even instances, now and then, of adult males grooming each other—a behavior nearly as unprecedented as baboons sprouting wings.

This unique social milieu did not arise merely as a function of the skewed sex ratio (with half the males having died); other primatologists have occasionally reported on troops with similar ratios but without a comparable social atmosphere. What was key was not just the predominance of females but the type of male who remained. The demographic disaster—what evolutionary biologists term a “selective bottleneck”—had produced a savanna baboon troop quite different from what most experts would have anticipated.

But the largest surprise did not come until some years later. Female savanna baboons spend their lives in the troop into which they are born, whereas males leave their birth troop around puberty; a troop’s adult males have thus all grown up elsewhere and immigrated as adolescents. By the early 1990s, none of the original low aggression/high affiliation males of Forest Troop’s tuberculosis period was still alive; all of the group’s adult males had joined after the epidemic. Despite this, the troop’s unique social milieu persisted—as it does to this day, some 20 years after the selective bottleneck. In other words, adolescent males that enter Forest Troop after having grown up elsewhere wind up adopting the unique behavioral style of the resident males. As defined by both anthropologists and animal behaviorists, “culture” consists of local behavioral variations, occurring for nongenetic and nonecological reasons, that last beyond the time of their originators. Forest Troop’s low aggression/high affiliation society constitutes nothing less than a multigenerational benign culture.

Continuous study of the troop has yielded some insights into how its culture is transmitted to newcomers. Genetics obviously plays no role, nor apparently does self-selection: Adolescent males that transfer into the troop are no different from those that transfer into other troops, displaying on arrival similarly high rates of aggression and low rates of affiliation. Nor is there evidence that new males are taught to act in benign ways by the residents. One cannot rule out the possibility that some observational learning is occurring, but it is difficult to detect, given that the distinctive feature of this culture is not the performance of a unique behavior but the performance of typical behaviors at atypically extreme rates.

To date, the most interesting hint about the mechanism of transmission is the way recently transferred males are treated by Forest Troop’s resident females. In a typical savanna baboon troop, newly transferred adolescent males spend years slowly working their way into the social fabric; they are extremely low ranking—ignored by females and noted by adult males only as convenient targets for aggression. In Forest Troop, by contrast, new male transfers are inundated with female attention soon after their arrival. Resident females first present themselves sexually to new males an average of 18 days after the males arrive, and they first groom the new males an average of 20 days after they arrive, whereas normal savanna baboons introduce such behaviors after 63 and 78 days, respectively. Furthermore, these welcoming gestures occur more frequently in Forest Troop during the early post-transfer period, and there is four times as much grooming of males by females in Forest Troop as elsewhere. From almost the moment they arrive, in other words, new males find out that in Forest Troop, things are done differently.

At present, I think the most plausible explanation is that this troop’s special culture is not passed on actively but simply emerges, facilitated by the actions of the resident members. Living in a group with half the typical number of males, and with the males being nice guys to boot, Forest Troop’s females become more relaxed and less wary. (This is so, in part, because in a typical baboon troop, a male who loses a dominance interaction with another male will often attack a female in frustration.) As a result, they are more willing to take a chance and reach out socially to new arrivals, even if the new guys are typical jerky adolescents at first. The new males, in turn, finding themselves treated so well, eventually relax and adopt the behaviors of the troop’s distinctive social milieu.

Natural born killers?

Are there any lessons to be learned here that can be applied to human-on-human violence—apart, that is, from the possible desirability of giving fatal cases of tuberculosis to aggressive people? Can human behavior be as malleable—and as peaceful—as Forest Troop’s?

Any biological anthropologist opining about human behavior is required by long-established tradition to note that for 99 percent of human history, humans lived in small, stable bands of related hunter-gatherers. Game theorists have shown that a small, cohesive group is the perfect setting for the emergence of cooperation: The identities of the other participants are known, there are opportunities to play games together repeatedly (and thus the ability to punish cheaters), and there is open-book play (players can acquire reputations). And so, those hunter-gatherer bands were highly egalitarian. Empirical and experimental data have also shown the cooperative advantages of small groups at the opposite human extreme, namely in the corporate world.

But the lack of violence within small groups can come at a heavy price. Small homogenous groups with shared values can be a nightmare of conformity. They can also be dangerous for outsiders. Unconsciously emulating the murderous border patrols of closely related male chimps, militaries throughout history have sought to form small, stable units; inculcate them with rituals of pseudokinship; and thereby produce efficient, cooperative killing machines.

Is it possible to achieve the cooperative advantages of a small group without having the group reflexively view outsiders as the Other? One often encounters pessimism in response to this question, based on the notion that humans, as primates, are hard-wired for xenophobia. Some brain-imaging studies have appeared to support this view in a particularly discouraging way. There is a structure deep inside the brain called the amygdala, which plays a key role in fear and aggression, and experiments have shown that when subjects are presented with a face of someone from a different race, the amygdala gets metabolically active—aroused, alert, ready for action. This happens even when the face is presented subliminally, which is to say, so rapidly that the subject does not consciously see it.

More recent studies, however, should mitigate this pessimism. Test a person who has a lot of experience with people of different races, and the amygdala does not activate. Or, as in a wonderful experiment by Susan Fiske, of Princeton University, subtly bias the subject beforehand to think of people as individuals rather than as members of a group, and the amygdala does not budge. Humans may be hard-wired to get edgy around the Other, but our views on who falls into that category are decidedly malleable.

In the early 1960s, a rising star of primatology, Irven DeVore of Harvard University, published the first general overview of the subject. Discussing his own specialty, savanna baboons, he wrote that they “have acquired an aggressive temperament as a defense against predators, and aggressiveness cannot be turned on and off like a faucet. It is an integral part of the monkeys’ personalities, so deeply rooted that it makes them potential aggressors in every situation.” Thus the savanna baboon became, literally, a textbook example of life in an aggressive, highly stratified, male-dominated society. Yet in my observation of Forest Troop, I saw members of that same species demonstrate enough behavioral plasticity to transform their society into a baboon utopia.

The first half of the twentieth century was drenched in the blood spilled by German and Japanese aggression, yet only a few decades later it is hard to think of two countries more pacific. Sweden spent the 17th century rampaging through Europe, yet it is now an icon of nurturing tranquility. Humans have invented the small nomadic band and the continental megastate, and have demonstrated a flexibility whereby uprooted descendants of the former can function effectively in the latter. We lack the type of physiology or anatomy that in other mammals determine their mating system, and have come up with societies based on monogamy, polygyny, and polyandry. And we have fashioned some religions in which violent acts are the entrée to paradise and other religions in which the same acts consign one to hell. Is a world of peacefully coexisting human Forest Troops possible? Anyone who says, “No, it is beyond our nature,” knows too little about primates, including ourselves.