The limits of the proposed 'behavioral immune system'

Many evolutionary psychologists argue that humans have a sophisticated ‘behavioral immune system’. We are, so the story goes, endowed with a suite of sophisticated, evolved psychological mechanisms that enable us to effectively detect and avoid disease causing parasites and pathogens. Unfortunately, work on the ‘behavioral immune system’ is plagued by one key methodological issue, and ethnographic evidence points to a more complex picture.

The core problem with existing research on the ‘behavioral immune system’ is that it is largely restricted to surveying people in modern nation-state societies. This is a big problem for two reasons. One, people in modern nation states tend to be aware of the germ theory of disease. That is, for cultural-historical reasons, they have scientifically informed knowledge of how disease is transmitted. This means disease-avoidance behavior can follow for reasons that are socially learned, and not the result of evolved mechanisms to avoid pathogens per se.

Consider for example an ethnographic account I wrote of previously, which demonstrates the behavioral contrast between someone with culturally learned knowledge of how pathogens spread compared to beliefs in a society with a different understanding of disease: “In The Afterlife is Where We Come From (2004), anthropologist Alma Gottlieb describes her fieldwork among the Beng farmers of West Africa. In this book, Gottlieb recounts her failure to persuade Beng villagers to boil their drinking water;

During our stays in Beng villages, Philip and I have always either boiled or filtered our own drinking water. To our dismay, our neighbors often derided our laborious efforts. One day we thought to explain our mysterious actions. The village had been experiencing an especially crippling outbreak of Guinea worm. After reading about the disease, Philip and I were convinced that polluted drinking water was the cause of our neighbors’ misery. We urged our friends to boil their water as protection against future infestation. But even our closest and most open-minded friends dismissed our suggestion with casual laughter.

“Can you see the worms in our water?” our friend Yacouba challenged us. We admitted we couldn’t.

“There’s nothing wrong with the water,” he insisted. “Anyway, even if the Guinea worms come to us through the water, they’re put there by witches.” Yacouba added emphatically, “Boiling the water wouldn’t stop the witches.” (Gottlieb, 189).”

Second, people in state societies often have access to culturally developed antiseptic systems and substances, facilitating greater pathogen avoidance than was often possible historically. This is important for an evolutionary model—if we want to investigate a pan-human ‘behavioral immune system’, and consider how it evolved, we should be looking at behavior in places where people don’t have historically recent knowledge of the germ theory of disease or access to antiseptic inventions, where they have to grapple with pathogens in contexts more similar to our evolutionary history than the WEIRD environments of today.

Let us consider a few domains where there is evidence across traditional societies that complicates that ‘behavioral immune system’ framework.

First, putrid or rotting meat. Anthropologist Frank Marlowe writes of the Hadza hunter-gatherers of East Africa that, “the Hadza often eat very rotten week-old meat they scavenge from carnivores,” adding that, “The scavenged (and sometimes very rotten) meat also gives them stomachaches, even after they cook it, but not often enough to keep them from eating it.”

Anthropologist C.R. Hallpike touches on this a great deal in his book Ship of Fools, writing that, “In Papua New Guinea the people are even less fastidious about their pork when it is stinking, even cutting it up under water when the smell is too bad. And yes, sometimes they died from it. Biologists often tell us that we are protected by the vomiting reflex from eating meat that has begun to smell as it goes bad, but no one seems to have told primitive peoples about this.”

Missionary Angel Turrado Moreno writes among the Warao of the Amazon of the, “Fish and meat, half raw, spoiled, and even rotten, which they eat without the slightest scruple at any hour of the day or night.” Among the Yaghan of Tierra del Fuego beached whales were often feasted upon, even when putrid or rotting, and digestive disorders caused by spoiled meat were said to be common.

Now, to some degree this can fit within the ‘behavioral immune system’ framework, with the important acknowledgement that tradeoffs matter a great deal. In their paper on ‘Human pathogen avoidance adaptations’, evolutionary psychologists Joshua M. Tybur and Debra Lieberman write that, “Individuals should be more willing to accept the potential costs of infection via food if nutrients are more needed.” Under this logic, the willingness to consume rotting or putrid meat reflects necessity borne from a scarcity or shortage of nutrients. This seems reasonable, although I think this is something that would still require greater investigation.

It is clear that ecological and cultural factors play an important role in disease avoidance behaviors to a degree that indicates the limitations of assuming humans have a powerful and predictably expressed ‘behavioral immune system’. For example, opportunities for good hygiene are often quite rare across many small-scale societies, and even if they are ecologically possible cultural beliefs and knowledge determine to a large degree what hygiene practices do or do not develop. Hallpike writes that, “Where water is scarce and is arduous to fetch, drinking and cooking take priority over hygiene by a wide margin, and I never saw the Konso [of Ethiopia] (or the Tauade [of New Guinea], for that matter) wash their hands before eating.”

Anthropologist Ran Singh Mann writes among the Onge Andaman Islanders “The raw material for food is not properly cleaned. It is boiled in dirty water containing mud and dust. The utensil in which the food is cooked is hardly cleaned. It is used over and over again without being cleaned. Layers of dirt keep on accumulating on the utensils used for cooking and eating purposes. The dogs also eat the left-overs in the same containers.”

Beyond limited hygiene practices, extensive and visceral interactions with dead bodies offers one of the most powerful complications for the ‘behavioral immune system’ framework. Hallpike quotes a patrol officer writing in 1945 that among the Tauade, ““A recently bereaved widow had an arm bone, several rib bones and the complete hand of the late departed hanging on a string around her neck. She did not appear to mind the offensive odour.”” Among the Inuit on Kodiak Island, “Nobody was afraid to touch a corpse,” and burials would not be conducted until the fourth day after death, “Until then the corpse is never left alone,” and is given a place in the main room of the house. Rituals involving corpses where also common among whale hunters in the region: “The whale hunters preserved the bodies of renowned men in caves, where they assembled prior to the hunt, carried the corpses to nearby streams, laid them in the water, and drank from this water.”

Andaman Island girl wearing her sister’s skull. From Radcliffe-Brown (1922).

In Australia, James Dawson writes that, “Before the minds of the aborigines were poisoned by the superstitions of the white people, they had not the slightest dread of the dead body of a friend, nor had they any repugnance to remain beside it." And, as I noted in a previous article touching on this topic, anthropologist Bruce Knauft described mourning rituals among the Gebusi of New Guinea,

The following morning, Dugawe’s body was grossly bloated. His swollen limbs oozed corpse fluid, and his peeling skin exposed putrid yellowgreen flesh. His belly and even his genitals had swelled with the gases of decomposition. The stench was unforgettable; it burned up my nose, down my throat, and into my brain. Equally powerful were the actions of Dugawe’s female kin. With unearthly sobs, they draped themselves physically over the corpse, lovingly massaged its slime, and drew back its skin. They rubbed their arms and legs with the ooze of the body. Corpse fluid on one’s skin is a tangible sign of grief, of physical as well as emotional connection to the deceased—making one’s own body like the corpse. Seeing this, Dugawe’s departing soul was said to know how much they cared for him and ease his anger at having died, at least a little (Knauft, 51).

See also mummification practices among the Anga of New Guinea. And kuru, the prion disease that spread through ritual cannibalism among the Fore of New Guinea.

Blood rituals are also not uncommon. As I previously noted, “Men of the Arunta foragers of Australia would drink some of each other’s blood under the belief that it would make them stronger and prevent treachery. Anthropologists Francis Gillen and Walter Spencer wrote that, “If [a man] refused to drink the blood, then, as actually happened in one case known to us, his mouth would be forced open and blood poured into it, which would have just the same binding influence as if the drinking had been a voluntary one.” Gillen and Spencer also discuss practices of treating sickness with blood, adding that,

When a woman is very ill and weak, one of her male Umba, to whom she is Mia alkulla – that is, he is the son of one of her younger sisters – may volunteer to strengthen her with his blood, in which case all the women and children are sent away from her. The man draws a quantity of blood from [his] sub-incised urethra, and she drinks part of it, while he rubs the remainder over her body, adding afterwards a coating of red ochre and grease. [italics added]”

Warriors in some societies may smear the blood of enemies on their bodies, or consume body parts to gain power. Among the Ingalik hunter-gatherers of Alaska, “a warrior may eat the eye of a respected opponent whom he has killed. When such a thing is done, it is for the purpose of gaining an enemy's power.”

The ritual use of animal excreta also complicates the ‘behavioral immune system’ framework. Infants would be ritually bathed with female camel urine among the Bedouin pastoralists of the Middle East [camel urine has also been known to be traditionally consumed in many parts of the region], while male Nuer pastoralists of Sudan would ritually rub the ashes of cattle dung on their bodies. Among the Fulani of Niger, “The feces (belade) from the cow are used for healing purposes. Women sometimes cook the belade and rub it into their hair to make it look darker. Cow urine is considered to have healing capabilities as well, and people who have been ill for a long time wash with the urine.” Cattle dung is also commonly used among many pastoralists as fuel or building material, although this has a clearer and more direct function than its ritual usage.

To sum up, I am not arguing humans never avoid pathogens, or that they are completely unconcerned with doing so. I think universally across cultures humans do share some sort of disgust ‘instinct’, although what facilitates a disgust reaction is far more culturally and historically contingent than many evolutionary psychologists would likely expect, in ways that complicate an emphasis on our supposed ‘behavioral immune system’.

The Creation of Men and Women in Hunter-Gatherer Societies

In evolutionary biology, male and female tend to be defined very simply—males are the category of individuals that produce the smaller, relatively mobile gametes (sperm), while females are the ones who produce the larger, less mobile games (ova or eggs). In human societies, however, the categories of ‘man’ and ‘woman’, do not follow solely from biological differences, but are also associated with behavioral roles and social identity within groups. Across many hunter-gatherer and other small-scale societies, young boys and girls would commonly be socialized through ritual processes to be considered full-fledged men and women.

The Rite of the First Kill was of particular importance among the !Kung hunter-gatherers of the Kalahari. A !Kung boy was not allowed to marry until he had killed his first large game animal and undergone the Rite, where he was ritually scarified by his father or other kinsman. For !Kung girls, their passage into womanhood was marked at their first menstruation, as is common across hunter-gatherer societies more broadly. Anthropologist Lorna Marshall writes that at this ceremony,

The girl is isolated in a special scherm for the duration of the flow only. She must be covered by a kaross because the sun must not shine upon her, and her feet must not touch the ground. When she must go out to urinate or defecate, she is carried on the back of the old woman (not her mother) who attends her. It is not the menstrual blood but the girl herself who must be kept from touching the ground. She would get thin if she disregarded this taboo. Men and boys must not look at the girl and she must not look at them lest the men become highly visible to animals and unable to get near enough to them to shoot.

Among Andaman Islanders, as part of the initiation process, “Every boy and girl has to undergo the operation of scarification. This is begun when the child is quite young, and a small portion of the body is operated on. The operation is repeated at intervals during childhood, until the whole body has been scarified.” And further,

In the case of a girl the period of childhood is brought to a close by a ceremony that takes place on the occasion of her first menstrual discharge…On the occurrence of the first menstrual discharge the girl tells her parents, who weep over her. She must then go and bathe in the sea for an hour or two by herself. After that she goes back to her parents hut or to a special shelter that is put up for the occasion… She may not speak nor sleep for 24 hours. Her wants are attended to by her parents and their friends, who sit near her to keep her from falling asleep…The girl sits thus for three days. Early every morning she leaves the hut to bathe for an hour in the sea. At the end of the three days she resumes her life in the village. For a month following she must bathe in the sea every morning at dawn…On the occasion of this ceremony the girl is given a new name, her “flower-name,” and from this time till after the birth of her first child she is never addressed or spoken of by the name which she had as a child, but only by the name given to her at this ceremony.

Girls are often segregated and even hidden away at their first menstruation, as they, by virtue of their condition, are considered particularly powerful or dangerous at this time. Among the Tlingit of Alaska, “Almost the most important event in a woman’s life was her first menstruation, for her conduct during her long puberty confinement was supposed to influence not only her own future life for good or ill, but the fortunes of her relatives and of her future husband. For this reason she was surrounded by taboos and enjoined to perform magical tasks.” In the first few days she wasn’t supposed to eat or drink, and she would remain relatively isolated from the rest of the group for months, while being taught important lessons or practical skills that women must know. Anthropologist Frederica de Laguna writes that, “During the remainder of her period of seclusion, the girl was given various tasks to perform, not only to educate her in a practical way but as a magical “training.” For example, “When I was in the tent, they ripped sheets and I had to sew them. I just had a a quilt of my mother’s. I don’t know how many times she ripped it and I had to sew it together again.””

Anthropologist Jane Goodale describes a girl’s first menstrual rituals among the Tiwi of Australia, writing that,

During her first menstrual period the [young girl] is removed from the general camp and makes a new camp in the bush with a number of other women. Her companions usually include her mother, her co-wives, and any other senior women in her residential group. No men are allowed in this camp. [She] and her female companions remain in the bush camp for five to ten days. During this time [she] cannot dig yams, or gather or cook any food. Nor may she touch any food with her hands, but must either use a stick or have someone place the food in her mouth, for if she did any of these things, she would “by and by swell up.” She cannot touch any water, even in a container, but must wait for someone of lift the container to her lips, for otherwise she would fall ill. She cannot scratch herself with her fingers, but must use a stick, because later her arm might break. She cannot make a fire, for the flames might singe her arm and cause it to break at some future time. Breaking a stick in two is taboo, for it would cause her legs to break.

There was an intense and extensive ritual process for Tiwi boys as well, “it was a long drawn-out and elaborate affair, marked by successive stages or grades which began with the status of Marukumarni, which a boy entered when he was about fourteen, and did not end finally until he was around twenty-four.” The initiation began with a mock abduction when the boy was an early teen. Anthropologists Charles Hart and Arnold Piling write that,

Though the father instigated and stage managed the whole affair, he and his household were always thunderstruck when the cross-cousins—armed to the teeth and painted like a war party—arrived at his camp one evening and proceeded to carry off forcibly the yelling 14-year-old. He had to be dragged literally from the bosom of his family, with his mother screaming and trying to hide him and the father pretending to resist the invaders of his household. From then on, until the final stage (Mikingula) at age 24–26, the boy was completely under the authority of the men who carried him off. During these approximately ten to twelve years, he spent much of the time alone with them in the bush where the group lived a monastic existence, as a small band of isolates, speaking to no one (especially not to females) and obtaining their own food. During these phases the tutors guarded the boy as if he were literally a prisoner and taught him all the things—chiefly ritual matters—that grown men should know. At intervals the youth was allowed to go home, on week-end leaves so to speak, but when at home he had to observe all the silences, the modest demeanor, the taboos and the austerities of the isolated life. In monastic language, he was under a strict rule of obedience to his tutors.

While the Naskapi of Canada were said to not have had elaborate formal rituals of inititiation, anthropologist Julius Lips notes that, “the young hunter who passes the test of courage by killing a bear is henceforth regarded and treated as a man...if he happens to be the eldest son it is now he...who will inherit the hunting-ground.”

It is only after going through such trials or initiation processes that a boy attains the higher status that comes with manhood. Among the Aranda of Australia, “Boys are not allowed to handle real boomerangs, spears, or shields before they have undergone the first initiation ceremony. If they did so, the offence would be looked upon as an insult to the dignity of the men who have qualified and are thus entitled to the privilege of carrying such weapons on parade. The offence is in fact, on a point of decorum, similar to the case of a fellow in the ‘rank and file’ wearing the sword or insignia of his superior officer.””

While young women’s rituals are often oriented around menstruation, young men’s are more often associated with the hunt, or in some cases the introduction of spirit beings and the dynamics of the men’s secret cult. Among the Ona of Tierra del Fuego, anthropologist John Cooper writes that,

The adolescent boy is taken from his mother and obliged to fast and to undergo other physical and psychical tests. Endurance and stoicism, generosity, honesty, veracity, bravery, the duty of blood-revenge, observance of the marriage laws against incest and adultery, and other tribal virtues are solemnly inculcated. The grown men paint and dress up in masks to represent spirits, and proceed to terrorize the women and children and to test the courage of the boy candidate. Finally the boy, if found worthy, is told the truth about the supposed spirits and the purpose of the masquerading, namely, to keep the women in subjection, and he is threatened with dire punishment if he should ever reveal the secrets to the women or children.

Similarly, among the Hadza of East Africa, after a young man demonstrated success in hunting he would go through a deceptive ritual process and be allowed to join the men’s secret epeme feasts, where they consume the most desirable portions of various large game animals while hidden away from the women and children, with the story given that it was the epeme spirits consuming the meat.

We can see that these initiation practices revolve around socializing girls and boys to become responsible women and men, who will learn to fill their necessary obligations and social roles. In some societies, some individuals may even grow up filling an opposite-sex role. Anthropologist Will Roscoe writes that, "among Inuit and Athabaskan-speaking groups of the arctic and subarctic females were sometimes raised in accordance with names of male ancestors chosen for them before their birth, or they were given a male or mixed gender assignment because their family lacked or desired a son." Some societies also had social roles for ‘masculine’ women, or ‘feminine’ men, such as the ‘manly-hearted’ women of the northern Plains groups of Native America.

To be a ‘man’ or a ‘woman’ in many societies does not simply reflect a biological imperative, but is a social role that must be cultivated and developed through ritual. This is not to deny the relevance of biological factors—there is a reason why it is women commonly associated with menstruation, for example, and men are more commonly associated with the hunt. Yet there are complex social processes and notions of identity at work that go far beyond biology alone, along with cross-culturally varying beliefs about what it means to be a ‘man’ or ‘woman’.

Book Review: Humankind by Rutger Bregman

The aim of revision is to get the distortions to match the mood of the present times—Mary Douglas, How Institutions Think, 1986.

It is a curious thing, to reflect on one’s nature—not simply the nature of oneself, but that of their entire species—human nature. Being so close to the problem, how does a person escape their own cultural trappings and preferred values to understand the entirety of humanity, in all its different social and environmental contexts?

In Dutch historian Rutger Bregman’s case, he doesn’t.

Bregman’s latest book, Humankind: A Hopeful History, is less a history of humanity than an exercise in promoting a simplistic narrative about it to suit one’s own preferred cultural values. Consciously echoing Rousseau, with an update for the 21st century, the core argument is that humans are fundamentally ‘good’ (that is, egalitarian, cosmopolitan, feminist, and opposed to violence)—unless or until their minds happened to be poisoned by property ownership or corrupt leaders, which Bregman claims were lacking for most of human history. Since, as Bregman correctly notes, humans spent the vast majority—upwards of 95%—of our history living in groups reliant on hunting and gathering to survive, let us consider in detail how accurately he characterizes these social systems.

Bergman claims that “in prehistory women had been free to come and go as they pleased,” and that it was only with the rise of agriculture that we began to see arranged marriages and male control over female sexuality, but this is pure fiction. Among the !Kung hunter-gatherers of the Kalahari, anthropologist Richard Lee—a source Bregman selectively references for his claims about hunter-gatherer’s inherent peacefulness--notes that “All first marriages are arranged by parents, and the girls have little say in the matter.” Among the Kaska nomadic foragers of British Colombia, anthropologist John Honigmann writes that, “Ideally a man feels entitled to beat his wife if he suspects that she has been untrue to him,” although “not all men avail themselves of this permitted behavior.” Arranged marriages are customary across the majority of hunter-gatherer societies, and violence, directed towards one’s wife and/or another man, is a common male response to actual or suspected infidelity.

Bregman makes much of the fact that among the Ache hunter-gatherers of Paraguay, women tend to have numerous different husbands throughout their lifetimes, but what he leaves unmentioned—or perhaps is unaware of—is that this partially reflects the particularly challenging socioecological circumstances they live in. The Ache are heavily reliant on male hunting for their subsistence, with men contributing about 87% of the total calories. In part due to their extensive food sharing and significant reliance on male hunting, it is not uncommon for children without fathers to be killed by adult men, who don’t want to have to help provide for them. This pattern was sex-biased as well, with female infants and children significantly more likely to be killed than male children. Having at least one male partner around at all times for provisioning and social support was thus quite essential for child survival. Girls tended to marry very early as well, with 85% of them getting married before menarche (about 15 years of age).

Contrary to the available evidence, Bregman sums up his caricature, writing that, “For most of human history, then, men and women were more or less equal. Contrary to our stereotype of the caveman as a chest-beating gorilla with a club and a short fuse, our male ancestors were probably not machos. More like proto-feminists.”

Yet the Ache have literal club fights, which were utilized as a tool of social control by powerful adult men. Anthropologists Kim Hill and Ana Hurtado write that, “Before contact, middle-aged men between thirty-five and fifty-five years old were politically powerful and monopolized many fertile women in the population. Younger men were afraid of these “fully grown adult men” because of their strong alliances and the fact that they sometimes killed younger men in club fights.” Hill and Hurtado also note that, "In the first few days [after a club fight] some men might die, but most recovered, even if their skulls had been split after a direct hit. Many Ache men have multiple large dents in their skulls, evidence of past fights and their ability to recover."

Many hunter-gatherer societies had ‘men’s groups’ where initiated adult men would monopolize the best pieces of game for themselves. Among the Hadza hunter-gatherers of East Africa, men would have secret ‘epeme’ feasts, where they would consume the most desirable parts of the large game animals killed, which were forbidden to women, children and the uninitiated. Among the Mi’kmaq foragers of Canada, the missionary Father Le Clercq noted that, “The women, the children, the young boys who have not yet killed any moose, and all of those who are not in condition to go to war against the enemy, do not, as a rule, enter into the wigwams where there is feasting,” and instead must wait for the men to finish before they can have the remains. 

Speaking of “war against the enemy”, Bregman claims that it was the beginnings of sedentism and property ownership that led to the origins of warfare, “Scholars think there were at least two causes. One, we now had belongings to fight over, starting with land. And two, settled life made us more distrustful of strangers. Foraging nomads had a fairly laid-back membership policy: you crossed paths with new people all the time and could easily join up with another group.” 

In fact, however, in every region of the world where there is evidence of different nomadic forager groups neighboring each other, there are cases of intergroup violence. This pattern is thoroughly reviewed in a 2012 paper by anthropologists Richard Wrangham and Luke Glowacki, who write that, “External war has been described in each of the areas we reviewed based on evidence of intergroup killing, explicit fear of strangers, and/or avoidance of border zones,” and adding that the “cases of hunter-gatherers living with different societies of hunter-gatherers as neighbors show that the threat of violence was never far away.” 

Among the Innu (also known as the Montagnais-Naskapi)—another society Bregman selectively references—hunting grounds were inherited through the patriline, and if someone repeatedly trespassed without permission, “the owner of the hunting-ground will be entitled to shoot him,” and that, “if during the coming winter the crime is repeated and the rightful owner kills the illegal trapper or hunter the owner will not be brought to account,” anthropologist Julius Lips writes.

Bregman claims that, “Hunter-gatherers viewed nature as a ‘giving place’ that provided for everybody’s needs, and it never occurred to them to patent an invention or a tune,” but again this is completely mistaken. Many hunter-gatherer societies in fact did have systems of ownership of inventions and songs. Among the Yolngu of Australia, “art encoded meanings in the context of a revelatory system of knowledge, in which knowledge of certain 'levels' of meaning was restricted to a few individuals, and in which knowledge of the meaning of paintings varied according to an individual’s status. As with song, men maintained the secrecy of designs by restricting sensory contact with the medium,” writes anthropologist Ian Keen.

Anthropologist Peter Jordan notes that across many Northwest Coast fisher-forager societies, “Canoe makers had personal songs that they recounted at key stages in the production sequence…The canoe maker’s supernatural connections and songs were kept secret, and others were forbidden from watching him work.” Among many California forager populations, ‘world renewal’ dances were “sponsored by wealthy men, and enabled them to show their riches off to the wider regional community,” writes Jordan, adding that “these treasures were never exchanged at the events; the wealthy men did not part with their treasures.”

What comes across most strongly in Bregman’s distortion of hunter-gatherer societies is how condescending it is. All the struggle, all the inventiveness and vitality, all the deeply human conflict and self-interest and challenges of defending oneself, one’s family, one’s possessions, and one’s community have been handwaved away to suit Bregman’s own preferred values. That he felt the need to misrepresent the past and other cultures in order to provide a ‘hopeful’ history is rather a message of despair. Bregman presents hunter-gatherer societies as being inherently peaceful, antiwar, equal, and feminist likely because these are commonly expressed social values among educated people in his own society today. This is not history but mythology. 

It is also noteworthy how little actual research Bregman did on hunter-gatherer societies for his book, despite his sweeping claims purporting to describe them. Nearly all of his references to traditional societies come from secondary sources, and importantly, all of them are ones that appear uniquely amenable to his simplistic narrative, such as The Good Book of Human Nature by Carel van Shaik and Kai Mitchell, Blueprint: The Evolutionary Origins of a Good Society by Nicholas Christakis, Myths of Male Dominance by Eleanor Leacock, and the infamously flawed Sex at Dawn by Christopher Ryan and Cacilda Jethá.

The central problem throughout the book, beyond his selective reading and the imposition of his own preferred values onto human history, is that Bregman keeps perpetuating a false dichotomy between simplistic Rousseauian and Hobbesian narratives, while neatly landing on the side of the former. In reality, human beings everywhere are neither inherently freedom loving and peaceful, nor inherently coercive and violent, but can be either or both depending on their socioecological and cultural context. From the extreme violence and warfare within Europe detailed in Lauro Martines book Furies: War in Europe, 1450–1700, to the more recent ‘long peace’ in Europe since World War 2, history is a mass of ‘change and contradiction’. The idea that we must restrict ourselves to some simple narrative about human nature to offer hope for the future is not only an unreasonably simplistic notion but a historically unjustified one.

'The WEIRDest People in the World' gets polygyny wrong

Anthropologist Joseph Henrich has a new book out, The WEIRDest People in the World: How the West Became Psychological Peculiar and Particularly Prosperous. I have previously written a number of articles touching favorably on his work, in relation to monogamy, leadership, and cultural evolution, though I have also contested his, in my view, overemphasis on cultural group selection as an explanation for the social structure of the Ilahita Arapesh horticulturalists of New Guinea. I have not yet finished Henrich’s latest work, however it contains a section discussing polygyny (Chapter 8, pgs 256-263) that I believe is sufficiently flawed and misleading to warrant detailed criticism.  

One thing I have always appreciated about Henrich’s work is his focus on the importance of culture for understanding human behavior, and much of what I have read in his new book thus far follows that tradition, such as his rich description of the social norms characteristic of societies with patrilineal clans (pgs. 104-115). I was surprised, however, to see that his account of polygyny is a very simple evolutionary psychology model. He argues both men and women have an “evolved psychological push to polygynous marriage” (pg 259), yet the evidence he provides points to the severe limitations of this argument, and in some ways severely undercuts it.

Henrich writes that, “In the most comprehensive study, 90 percent of hunter-gatherer populations around the globe had some degree of polygynous marriage, while just 10 percent had only monogamous marriage.” However, this manner of dichotomizing full monogamy and any degree of polygyny is a highly debatable way of conceptualizing this, and stems from the coding decisions made by anthropologist George Murdock back when he created the Ethnographic Atlas and the Standard Cross-Cultural Sample [the EA and the SCCS are large datasets consisting of geographically and culturally diverse societies of multiple subsistence types coded on numerous variables]. Murdock and anthropologist Suzanne Wilson coded societies with less than 20% of marriages being polygynous as ‘limited polygyny’, yet they could have just as easily coded these societies as being ‘mostly monogamous’, in which case it would be clear most societies are mostly monogamous, and Henrich’s account would likely have to be framed quite differently.

Cross-cultural codes for the SCCS, from Murdock & Wilson (1972).

Indeed as Henrich notes, “Of the societies with polygyny, about 14 percent of men and 22 percent of women were polygynously married.” Meaning the majority of marriages across ‘societies with polygyny’ are in fact monogamous. If, then, the data shows that monogamy is the most common form of marriage cross-culturally, by a wide margin, why should these data be framed as humans having an “evolved psychological push to polygynous marriage,” rather than an ‘evolved psychological push to monogamous marriage’?

Of course, different researchers can prioritize different domains, and if polygynous marriage is extant across cultures, despite usually not being the most common form of marriage, then the ‘puzzle of polygynous marriage’ remains. Accepting this, is an ‘evolved psychological push to polygynous marriage’ the best explanation for the existence of polygyny cross culturally?

Henrich writes that, “The best move for a particular woman in a hunter-gatherer society might be to become the second wife of a great hunter instead of being the first wife of a poor hunter; this helps guarantee that children get both excellent genes and a steady supply of meat (a valuable source of nutrition).” While this may be true in some contexts, one of the papers Henrich cites actually demonstrates that this is an insufficient and often poor explanation for polygyny cross-culturally.

One paper Henrich cites on the prevalence of polygyny is Frank Marlowe’s 2003 paper ‘The Mating System of Foragers in the Standard Cross-Cultural Sample’. Marlowe found among hunter-gatherer societies in the SCCS “The percentage of polygynous women is higher where gathering contributes more to the diet (r= .477, p= .008, n= 30) and lower where fishing contributes more to the diet (r= –.550, p= .002, n=30), which is where males contribute the most.” This may seem puzzling until you realize what the mechanisms supporting polygyny tend to actually be. Marlowe found that, “Among foragers as well, there is a higher percentage of polygynous women where female marriages are arranged (r= .502, p= .009, n= 26). Assault frequency is also correlated with percentage of polygynous women (r= .672, p= .001, n= 22).” This is consistent with other work noting the ubiquity of arranged marriages across hunter-gatherer societies, as well as a recent replication from 2018 demonstrating the association between polygyny and assault frequency, as well as polygyny and arranged marriages, across societies in the SCCS.

As Marlowe himself summed it up in his 2003 paper cited by Henrich, “Among all 186 societies in the SCCS, there is greater polygyny where female marriages are arranged but not where male marriages are arranged (Marlowe, n.d.), suggesting that marriage arrangement is a form of male coercion and a way parents can benefit by supplying the most influential males with brides.”

Henrich does discuss arranged marriages and their coercive elements in other contexts, writing that among societies with patrilineal clans, “Norms about arranged marriages empower patriarchs to strategically use their daughters’ marriages to nourish their clan’s network of alliances and relationships.” (pg 107), and there is a strange disconnect when he notes among the Wathaurung of Australia that, “Men arranged marriages for their daughters or sisters, often when they were children or even infants. As in most hunter-gatherer societies, men could marry polygamously, with prestigious hunters and great warriors sometimes accumulating five or even six wives, leaving lesser men with no wives and few prospects.” (pg 60). This makes it quite odd that he never seems to connect arranged marriages to the practice of polygyny cross-culturally when this association is directly noted in one of the key papers he cites and clearly prevalent in the ethnography he discusses.

Henrich assumes polygynous marriages reflect an ‘evolved psychological’ bias on the part of both sexes towards such marriages, but as mentioned above polygynous marriages cross-culturally can often be a coercive arrangement where powerful males arrange such marriages for themselves or their kin (as Henrich noted among patrilineal clans, without making the connection to polygyny). From the male perspective, they can also be motivated by economic concerns just as much or even more than sex or companionship, as I discussed in detail here. As I noted in that piece, anthropologists Charles Hart and Arnold Piling write that among the Tiwi hunter-gatherers of Australia,

The most concrete symbol of Tiwi success was the possession of surplus food, for this not only permitted its possessor to make gifts to others and throw large parties for which he picked up the check, but also gave him lots of leisure time to devote to social and political life. Since a man required a large number of women in his work force if he was to build up a surplus of food, in the final analysis it was control of women that was the most tangible index of power and influence. Women were the main currency of the influence struggle, the main “trumps” in the endless bridge game.

Notably Tiwi practices of polygynous marriages could not possibly be attributed to any ‘evolved psychological push’ on the part of women towards such marriages, as they, like the Wathaurung, practiced infant bestowal, where young girls would be promised in marriage arrangements orchestrated by their male kin, often before they were even born—a not altogether uncommon form of marriage arrangement across some hunter-gatherer societies. They also had strong social norms requiring every woman to be married, and as a consequence practiced compulsory widow remarriage.

Consistent with the economic incentive for polygyny, among the Asmat hunter-gatherers of New Guinea, at marriage a man would gain access to the highly valued sago patches that his wives inherited through their matrilines. His wives would provide the labor necessary to process the sago enabling him to throw feasts and gain status, similar to the Tiwi example where female labor is a path to increasing male status. Anthropologist Bruce Knauft goes into detail on the coercive and economic dimensions of Asmat marriage practices, writing that,

Polygyny and control of female labor in sago production were a significant dimension of male status differentiation, and in cases of polygynous marriage, second wives "may be little more than drudges" unless they were sisters to the first wife (Eyde 1967:194; cf. Trenkenschuh 1982a:46). Wife-beating was assessed by Eyde (1967:192) to have been quite common among central Asmat, and he says, "only where a wife-beating becomes near-murder, or actually results in murder, will her brothers intervene." He documents four cases that came to his attention in which men in fact murdered their wives. Unmarried women could be beaten by their fathers or brothers for promiscuity (ibid. :220).

Even beyond more coercive arrangements and economic motives, polygyny can be highly influenced by cultural norms in other ways, such as through sororal polygyny (where co-wives are sisters). Among the Dobe Ju/'Hoansi hunter-gatherers of the Kalahari, anthropologist Richard Lee found a relatively small percentage of polygyny, as well as a polyandrous union “In a sample of 131 married men in 1968, 122 (93 percent) were living monogamously, 7 (5 percent) were living polygamously (6 with 2 wives, 1 with 3), and 2 men (2 percent) were living in a polyandrous union, sharing 1 woman.” And of these, “Three of the 7 cases were sororal polygyny, while in 4, the co-wives were unrelated.” Among the Kaska hunter-gatherers of British Colombia, marriages were generally arranged, monogamy was the norm, and polygyny and polyandry co-existed in relation to economic needs, with polygyny always being sororal. Anthropologist John Honigmann notes that,

Monogamous families were most common. Few men could afford to support as many as two wives and the children they produced. Polygyny was sororal in type. Even a widower had trouble securing permission to marry a woman other than his deceased's wife's sister, parents-in-law showing particular possessiveness about a man renowned as a hunter. To bring an unrelated woman into the family constituted a signal for the first wife to quit her husband and go home. No bride service attended marriage to a subsequent wife. Polyandry appears to have been restricted to old men who were unable to hunt sufficiently to support their families.

Note further that here it is the parents-in-law in particular preferring a good hunter, consistent with the common cross-cultural practice of ‘bride service’ across many hunter-gatherer societies, where the husband or prospective husband provides goods and services to their in-laws for a period of months or years at the start of marriage (or sometimes longer). As the Kaska practiced bride service for the first marriage, but not for second wives, this preference for sisters if polygyny occurred makes even more sense, as they were coming from the same household, where the man was likely already providing for his in-laws (notably the Dobe Ju/'Hoansi also practiced bride service). This makes a great deal of sense when you think of how marriages are often an economic arrangement between families across many traditional societies, rather than projecting the modern WEIRD norm and assuming such marriages are the result of autonomous individuals engaging in free choices. Henrich himself actually gives a great description related to this in the chapter on ‘WEIRD Families’, writing that,

In pre-Christian Europe, as in much of the world until recently, marriage customs had evolved culturally to empower and expand large kin-based organizations or networks. Marital bonds establish economic and social ties between kin-groups that foster trade, cooperation, and security. To sustain such ties, long-term marital exchanges are necessary…In patrilineal societies, senior males—the patriarchs—administer these ongoing spousal exchanges and thus use the marriage of their sisters, daughters, nieces, and granddaughters to cement relations with other kin-groups and nourish important alliances. Arranged marriages thus represent a key source of patriarchal power (pg 167) [emphasis added].

It’s unfortunate he doesn’t connect this pattern to the practice of polygyny, and instead offers a simplistic free choice model in the polygyny chapter.

These social institutions demonstrate the importance of considering cultural norms (and other dimensions of socioecology) for understanding both polygyny and monogamy, as well as other cross-cultural practices, as Henrich has effectively argued previously and in other parts of his new book.

For more on polygyny cross-culturally, see my piece for Areo Magazine ‘How Coercive is Polygyny?’