An Introduction to Domestication

Part Of: Anthropogeny sequence
Content Summary: 1300 words, 13 min read.

The Domestication Syndrome

Since our emigration out of Africa 70,000 years ago, Homo Sapiens have domesticated many other species, including

  • dogs (18 ka, first domesticated in Germany)
  • goats, sheep (11 ka)
  • cattle, pigs, cats (10 ka)
  • llamas, horses, donkeys, camels, chickens, turkeys (5 ka)
  • foxes (50 years ago)

Consider the domestication of wolves into dogs. An important part of the environment of a species is other species- not merely its predators or pathogens but its symbionts. In this case, canines began to get food from human campsites. Dogs that were less aggressive were (by unconscious preference and conscious intent) more successful at extracting resources. This process is known as artificial selection.

Most ancient dogs kept by hunter-gatherers share a common body shape. More recently however, humans have conducted pedigree breeding: influencing the morphologies of different dog breeds. We have used this power to sculpt breeds as diverse as the Chihuahua and the Great Dane.

The defining feature of domestication is docility: a reduction in reactive aggression. All domesticated species exhibit this feature, in comparison to their wild counterparts. Not all species are capable of this sort of control. For example, humanity has tried for centuries to domesticate big fauna such as zebras, lions, and hippos. However, some breeds have reproductive and aggressive styles that prohibit domestication.

But domestication doesn’t just bring about a change in behavior. It also brings with it a bewildering number of anatomical changes, to essentially all domesticated species. The domestication syndrome include:

  • Docility (agreeableness, reduction in irritability)
  • Depigmentation (especially white patches, brown regions)
  • Floppy ears
  • Shorter ears
  • Shorter jaws
  • Smaller teeth
  • Smaller brains (10-15% reduction in volume)
  • More neotenous behavior (juvenile behavior that extends into adulthood).
  • Curly tails

Most domesticated species express some aspect of the domestication syndrome, as we can see in the following table:

Self-Domestication_ The Domestication Syndrome (1)

Three Theories of Domestication

The sheer complexity of the domestication syndrome requires an explanation. What is the link between floppy ears and docility?

Three hypotheses suggest themselves:

  1. Multiselection. Are the symptoms of domestication all expressions of human preferences? Do we simply like curly tails and floppy ears?
  2. Environment. Is there something about proximity to humans that incentivizes these changes?
  3. Byproduct. When the genes for aggression are altered, does that somehow incidentally cause these other changes?

Animal husbandry practices are lost to the sands of time. Nevertheless, there is a way to test multiselection directly: by creating a domesticated species in the laboratory.

In 1959, Dmitri Belyaev began trying to domesticate silver foxes. He used exactly one criterion for selection: he only bred pups that exhibited the least aggression. Skeptics thought it would take centuries to complete the domestication process. But changes in temperament were seen after only four generations. At twelve generations, “elite” foxes began to emerge with dog-like characteristics: wagging their tails, allowing themselves to be petted etc. At twenty generations, the entire population was considered fully domesticated.

Despite only selecting for docility, Belyaev’s foxes exhibited the full domestication syndrome. The foxes inexplicably developed floppy ears, curly tails, white patches, etc etc. The multiselection hypothesis is false.

Is there something about proximity to humans that selects for the domestication syndrome? The environment hypothesis seems false for two reasons. First, when they return to the wild, domesticated species take a long time reverting their characteristics. In fact, often domestication gives them a selective advantage over their wild cousins. Second, as we will see in the next section, self-domesticated species such as bonobos exhibit the syndrome despite their evolution not being influence by hominids.

The byproduct hypothesis is our only remaining explanation for the domestication syndrome. But what specific system produces these changes? 

The Biological Basis of Domestication

In order to fully explain aggression reduction, we must understand it at a biological level.

The primary basis of aggression reduction is a shrinking amygdala and periaqueductal gray (PAG). These modules comprise the negative valence system which learn which stimuli are negatively-valenced, and forward them to the mobilization system (e.g., snake → bad → run away). Serotonin inhibits the negative valence system, and domesticated animals have much high concentrations of serotonin receptors in these regions. Finally, it appears that these changes mostly act across development. The negative valence system comes online only slowly: there exists a socialization window in the first month of a wolf’s life, where it can learn “humans are okay”. Domestication primarily acts by increasing the socialization window from one to twelve months. If a dog isn’t exposed to a human in its first year, it’s now-active fear system will kick in: it will be wild for the rest of its life.

So what biological system is able to a) expand the socialization window, and b) cause the rest of domestication syndrome? The leading hypothesis involves a feature of development called the neural crest.

A blastocyst has no brain. To correct this unfortunate situation, every vertebrate genome contains instruction for constructing a neural tube. This structure emerges via folding.

The neural crest resides between the epidermis and the neural tube. These neural crest cells (NCCs) then proceed to migrate to a certain number of other anatomical structures to assist development. When the NCC migration malfunctions, the resultant disease is called a neurocristopathy. Many neurocristopathies result in outcomes similar to the domestication symdrome! For example, here is the effect of piebaldism:

Self-Domestication_ Piebalism

The mild neurocristopathy hypothesis (Wilkins et al, 2014) holds that domestication syndrome is a byproduct of changes to the NCC migration pattern.

Self-Domestication_ Mild Neurocristopathy Hypothesis

The hypothesis, however, is not very detailed (how exactly is NCC migration changed? What are the genomic and epigenomic contributions?). It is more of a promissory note than a mechanistic account. And there are other holistic hypotheses on offer, including genetic regulatory networks (Trut et al 2004) and action of the thyroid gland (Crockford 2000). It seems clear that, in the coming decades, a detailed mechanistic theory of domestication will emerge to vindicate the byproduct hypothesis.

Two Kinds of Domestication

Natural selection explains why the “design requires a designer” trope is obsolete. For the same reason, domestication can occur in the absence of a domesticator. More precisely, change in a species ecological niche can itself select against aggression.  Because aggression is very relevant to survival, we see plenty of species that have increased, and plenty that have decreased their rates of aggression. We call those less aggressive species self-domesticated: they became more peaceful in the absence of humans. What’s more, these species also exhibit the domestication syndrome.  

Another example is embedded in Foster’s Rule. Islands tend to be geologically more recent than continents, so their populations derive from the continent rather than vice versa. Islands tend to have fewer predators, but also fewer resources. Reduced predation increases the size of small animals (e.g., dodos evolved from pigeons), but limited resources decreases the size of big animals (e.g. the 3ft tall dwarf elephant).  

Self-Domestication_ Foster's Rule

Because islands have fewer predators, they also tend to have higher population densities; as such, reactive aggression is a less useful strategy. Selection favors the less aggressive. And we can see the domestication syndrome in island species. For example, the Zanzibar red colobus monkey has diverged from the continental red colobus along the same trajectory as dogs diverged from wolves.

Other examples of self-domestication can be found with group size reduction (ungulates, seals) and low-energy habitats (extremophile fish).

Finally, bonobos provide a particularly relevant example of self-domestication. Because food is more plentiful (don’t have to compete with gorillas for vegetation), females can spend time close to one another. Proximity produces bonding, and female coalitions exert pressure on bonobo behavior.

  • In chimps, bullying women increases reproductive success. Chimps will systematically beat up all females in their group as a coming-of-age ritual.
  • In bonobos, female coalitions retaliate against male aggression, making it unprofitable. Sexual selection then acts against reactive aggression.

So we can see that domestication (i.e., reduction in aggression) can come in two flavors: traditional vs self-domestication.

Self-Domestication_ Categories of Aggression Reduction (1)

As we will see next time, Homo Sapiens is yet another example of a self-domesticated species. See you then!

Related Resources

  • Wilkins et al (2014). The “domestication syndrome” in mammals: a unified explanation based on neural crest cell behavior and genetics

[Excerpt] Replicators and their Vehicles

Original Author: Richard Dawkins, The Selfish Gene
See Also: [Excerpt] The Robot’s Rebellion
Content Summary: 800 words, 4 min read

The First Replicator

Geochemical processes gave rise to the “primeval soup” which biologists and chemists believe constituted the seas some three to four thousand million years ago. The organic substances became locally concentrated, perhaps in drying scum round the shores, or in tiny suspended droplets. Under the further influence of energy such as ultraviolet light from the sun, they combined into larger molecules. Nowadays large organic molecules would not last long enough to be noticed: they would be quickly absorbed and broken down by bacteria or other living creatures. But bacteria and the rest of us are late-comers, and in those days large organic molecules could drift unmolested through the thickening broth.

At some point a particularly remarkable molecule was formed. We will call it the Replicator. It may not necessarily have been the biggest or the most complex molecule around, but it had the extraordinary property of being able to create copies of itself.

A molecule which makes copies of itself is not as difficult to imagine as it seems at first, and it only had to arise once. Think of the replicator as a mold or template. Imagine it as a large molecule consisting of a complex chain of various sorts of building block molecules. The small building blocks were abundantly available in the soup surrounding the replicator. Now suppose that each building block has an affinity for its own kind. Then whenever a building block from out in the soup lands up next to a part of the replicator for which it has an affinity, it will tend to stick there. The building blocks which attach themselves in this way will automatically be arranged in a sequence which mimics that of the replicator itself. It is easy then to think of them joining up to form a stable chain just as in the formation of the original replicator. Should the two chains split apart, we would then have two replicators, each of which can go on to make further copies.

Replicator Competition

The primeval soup was not capable of supporting an infinite number of replicator molecules. For one thing, the earth’s size is finite, but other limiting factors must also have been important.

But now we must mention an important property of the copying process: it is not perfect. mistakes will happen. I hope there will be no misprints in this book, but if you look carefully you may find one or two. We do not know how accurately the first replicator molecules made their copies. Their modern descendants, the DNA molecules, are astonishingly faithful compared with the most high-fidelity human copying process, but even they occasionally make mistakes, and it is ultimately these mistakes which make evolution possible. Mistakes were made, and these mistakes were cumulative.

Replicators with a comparatively worse design must actually have become less numerous because of competition, and ultimately many of their lines must have one extinct. There was a struggle for existence among replicator varieties. They did not know they were struggling, or worry about it; the struggle was conducted without any hard feelings, indeed without feeling of any kind. But they were struggling, in the sense that any mis-copying which resulted in a new improved level of stability, or a new way of reducing the stability of rivals, was automatically preserved and multiplied.

This process of replicator improvement was cumulative. Ways of increasing stability and of decreasing rivals’ stability became more elaborate and more efficient. Some of them may even have ‘discovered’ how to break up molecules of rival varieties chemically, and to use the building blocks so released for making their own copies. These proto-carnivores simultaneously obtained food and removed competing rivals. Other replicators perhaps discovered how to protect themselves, either chemically, or by building a physical wall of protein around themselves. This may have been how the first living cells appeared.

Replicator Self-Improvement

Replicators began not merely to exist, but to construct for themselves containers, vehicles for their continued existence. The replicators that survived were the ones that built survival machines for themselves to live in. The first survival machines probably consisted of nothing more than a protective coat. But making a living got steadily harder as new rivals arose with better and more effective survival machines. Survival machines got bigger and more elaborate, and the process was cumulative and progressive.

Was there to be any end to the gradual improvement in the replicators’]techniques? What weird engines of self-preservation would the millennia bring forth?  Four thousand million years on, what was to be the fate of the ancient replicators?

They did not die out, for they are past masters of the survival arts. But do not look for them floating loose in the sea; they gave up that cavalier freedom long ago. Now they swarm in huge colonies, safe inside gigantic lumbering robots, sealed off from the outside world, communicating with it by tortuous indirect routes, manipulating it by remote control..

They are in you and in me; they created us, body and mind; and their preservation is the ultimate rationale for our existence. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines.

[Excerpt] Self-domestication and human homosexuality

Excerpts are not my writing! This comes from Richard Wrangham’s book:

The Goodness Paradox: The Strange Relationship Between Virtue and Violence in Human Evolution

It was a fun read. Recommended!

Human homosexuality is not adaptive

The hypothesis that human homosexuality is adaptive (genetically advantageous) has not been rejected lightly. Homosexual behavior can be frequently found among wild animals, and traits that are widespread are likely to be adaptive.

So when evolutionary biologists began to study human homosexual behavior, they tended to search for ways to explain how a same-sex preference might have been favored in natural selection. Homosexual behavior among other animals offered some ideas.

Close study reveals how homosexual behavior can be adaptive.

  1. Scarcity of opposite-sex partners. Among Laysan albatrosses in Hawaii, two parents are needed for chicks to be reared successfully. When there are not enough males, females pair together. Their sexual behavior includes courtship and pseudo-copulation. Females in same-sex pairs are fertilized by an already mated male, who then ignored the resulting eggs and chicks. The female pair brings them up without male help.
  2. As a prosocial device. In animals whose choice of sexual partner is not a response to a shortage of opposite-sex partners, homosexual behavior sometimes appears to be adaptive by promoting useful social relationships. In troops of Japanese monkeys, females form temporary homosexual mating partnerships even when other males are available. Among savanna baboons, males form alliances that they use in fights against others. Allies reciprocally fondle one another’s genitals, apparently to demonstrate their commitment to the bond.

Researchers have sought evidence that the kinds of reproductive or social benefits that animals gain from same-sex sexual interaction might be found in human. In theory, humans could form same-sex partnerships in response to a short supply of members of the opposite sex. Certainly, partner availability influences us. Women and men in single-sex institutions such as prisons, schools, monasteries, and ships often temporarily shift their sexual activity toward their own sex. Nevertheless, of course, many individuals feel an exclusive attraction to members of their own sex, regardless of the availability of the opposite sex.

Further, homosexual couples tend to have smaller families than same-sex couples, and there is a lack of evidence that their sexual orientation leads them to give exceptional help to their genetic kin. These data suggest that homosexual behavior in humans is not biologically adaptive.

Unfortunately, the conclusion that same-sex behavior is not adaptive has sometimes been associated with a negative view of homosexuality. But normative value and biological purpose are independent considerations. Many tendencies that we regard as morally reprehensible clearly evolved, including numerous kinds of sexual coercion, lethal violence, and social domination. Equally, many morally delightful tendencies did not evolve, such as charity to strangers and kindness to animals. Our decisions about which behavior we like or dislike should never be attributed to adaptive value.

The biological basis of homosexuality

Same-sex sexual attraction is often stable over a lifetime, and there is good evidence that is is partly heritable. These features make human homosexuality different from most animal homosexuality.

One particular area of the brain responds to androgens (sex hormones) in the fetal stage: the third interstitial nucleus of the anterior hypothalamus (INAH3). The INAH3 is larger in heterosexual men than in women, and has been found to be intermediate-sized in homosexual men. In an adult rams, experimentally reducing the comparable nucleus (oSDN) causes them to change his sexual-partner preference from female to male.

Homosexual preference is more likely in males who receive low testosterone exposure before birth. A standard method for assaying prenatal testosterone exposure is to measure the length of the ring finger (the fourth finger) compared to the length of the second finger: increased prenatal exposure to testosterone tends to be associated with relatively long ring fingers. The largest surveys of homosexual men in the United States, China, and Japan have found a tendency for homosexual women to have relatively long ring fingers, whereas homosexual men have relatively short ring fingers. Homosexual men also tend to have somewhat feminized face shapes and shorter, lighter bodies than heterosexual men, most likely from relatively low exposure to testosterone in the womb. In general, females who have been exposed to higher-than-usual levels of androgens, and males who have been exposed to lower-than-usual levels, appear to have a higher likelihood of being homosexual.

Homosexuality as a by-product of self-domestication

The evidence that exclusive homosexual preference is common but not adaptive makes it a prime candidate for being an evolutionary by-product.

Elsewhere, I have presented the self-domestication hypothesis: the theory that H. sapiens domesticated itself; that is, it selected against reactive aggression. Testosterone is involved both in male violence, but also sexual preference.

But since reduced testosterone is a common effect of domestication, homosexual orientation in this species appears to be explicable ultimately as an incidental consequence of selection against reactive aggression.

Some additional evidence are suggestive:

  • The only nonhuman animal in which exclusive homosexual preference is known is a domesticated species – namely, sheep.
  • At least 19 species of domesticated animals show homosexual behavior, though it occurs in their wild relatives as well.
  • Our two closest primate relatives are chimpanzees and bonobos. Chimpanzees are non-domesticated (highly aggressive) and have long ring fingers suggesting high prenatal exposure to testosterone. Bonobos are self-domesticated (placid), and have short index fingers.
  • Homo neanderthalensis morphology indicates they were quite an aggressive species (non-domesticated), and they shows a large finger-length ratio. The 100,000-year-old H. sapiens at Qafzeh is in-between the ratios for living humans and the five Neanderthals.

Thus, it may be that self-domestication (the source of our species’ remarkable ability for cooperation) yielded homosexual behaviors as a by-product.



[Sequence] History

I have blogged some on the history of ancient Israel, here:

I have also done some research on the Middle Ages, and the Bronze Age collapse of civilization. I’m hoping to someday present these data, in context of the theory of cliodynamics.

Related Content

Moral Foundations Theory

Part Of: Demystifying Ethics sequence
Content Summary: 1700 words, 17 min read

The contents of our social intuitions is not arbitrary. They are not entirely plastic to changes in environment. Rather, the brain are built with innate social intuition generators, which bias the content of social judgments.

Generator 1: Care/Harm

Parents care for their children. This imperative of natural selection is directly expressed in caregiving mechanisms in the brain. While the proper domain of caregiving is one’s kin, other modules (such as the mammalian attachment module) can elicit caregiving behaviors towards non-kin.

For primates living in close proximity, male violence is an increasingly noxious threat. Accordingly, Cushman et al (2012) show evidence for a violence aversion device, which triggers a strong autonomic reaction to actions of violence committed by oneself (but not others). Here is an example of their experimental apparatus: underneath the X is a fake leg. Even though they knew the action was harmless, delivering the blow caused significant visceral distress, compared to watching it being done by someone else. moral foundations_ violence aversion (1)

The violence aversion device is sensitive to calculations of personal force which is used to generate feelings of agency in the brain. The alarm only triggers when our body directly delivers force onto another person. This explains why the alarm triggers in the footbridge dilemma (“push the fat man to save five lives”) but not the trolley problem (“flip a switch to kill one and save five”).

Generator 2: Proportional Fairness

Main Article: Evolutionary Game Theory

When interacting with other organisms, one can act purely selfishly or cooperatively. The Prisoner’s Dilemma illustrates that acting in one’s self-interest can lead to situations where everyone loses. There is strong evolutionary pressure to discover cooperative emotions: devices that avert the tragedy of the commons.

The Iterated Prisoner’s Dilemma (IPD) makes game theory more social, where many players compete for resources multiple times. While one-off PD games favor selfish behavior, IPD can favor strategies that feature reciprocal altruism, such as Tit-for-Tat. More generally, IPD strategies do best if they are nice, retaliating, and forgiving.

Social equality is a special case of proportionality: when contributions are equal, so too should rewards. But when contributions are unequal, most adults affirm reward inequality. We have a deep intuitive sense of karma: what people deserve depends on how much effort they expend.

Generator 3: Dominance

Main Article: An Introduction to Primate Societies

When animals’ territory overlaps, they often compete for access to resources (e.g., food and reproductive access).

Fighting is accompanied with risk: the stronger animal could be unlucky, the weaker animal could lose their life. Similar to human warfare, both sides suffer less when the weaker side preemptively surrenders. The ability to objectively predict the outcome of a fight is therefore advantageous.

Suppose the need for fight-predictions is frequent, and do not often change (physical strength changes only slowly over an animal’s life). Instead of constantly assessing physical characteristics of your opponent, it is simpler to just remember who you thought was stronger last time.

This is the origin of the dominance hierarchy. The bread and butter of dominance hierarchies is status signaling. Dominant behaviors (e.g., snarling) evokes submissive behaviors (e.g., looking away).

Generator 4: Autonomy

Consider the following facts.

  1. The earliest groups of humans seem to have been governed by an egalitarian ethic, much as surviving communities of nomadic hunters and gatherers still are.
  2. That ethic is unique among other species of great apes that are our closest cousins. Most notably, chimps and gorillas live in bands led by despotic alpha males.
  3. As human societies developed settled agriculture and then civilization, despotism and hierarchy reemerge.

How can we explain these things? Perhaps a new emotional system evolved: autonomy. It motivated groups of non-dominant humans to form coalitions against any potential alpha despot. This trend is born out in the data: about half of all murders cross-culturally have an anti-bullying motive. But murder is not the only sanctioning device, followers also use techniques such as criticism, ridicule, disobedience, deposition, and desertion (Boehm, 2012).

Our species never lost its capacity for despotism. But in the human inverted hierarchy, our species discovered a newfound will to tear down authority figures, which created within us a capacity for egalitarianism. These two systems (Autonomy and Dominance) live in tension with one another, and one can “gain the upper hand” by changes in the broader cultural milieu (cf., agriculture and the collapse of egalitarian societies).

Generator 5: Purity / Disgust

Main Article: The Evolution of Disgust

The human brain comes equipped with two systems:

  1. Poison monitoring is a faculty of the digestive system. It evolved to regulate food intake and protect the gut against harmful substances.
  2. Infection avoidance is a faculty of the immune system. It evolved to protect against infection from pathogens and parasites, by avoiding them.

In humans, these two systems were entangled in the emotion of disgust. This explains the otherwise baffling diversity of disgust elicitors & behaviors.

Disgust motivated the creation of food taboos (e.g., don’t eat pork) and purity laws (e.g., don’t put your feet on the table).

Generator 6: Group Loyalty

Two people can put Us ahead of Me by belonging to a cooperative group, provided that group members can reliably identify one another. Specifically, we possess a group membership device which uses symbols to delineate different factions. Members of the ingroup are treated warmly (ethnocentrism); members of the outgroup are treated poorly (xenophobia). We even pay more attention to members of the ingroup, leading to such phenomena as outgroup homogeneity (c.f., evangelical Christians describing non-evangelicals as “the world”).

Ethnic psychology describes modules in our brain responsible for constructing groups. We are particularly interested in constructing stereotypes of other groups. Our brains already come equipped with folk biology modules that delineate different species of flowers, for example. Gilwhite et al (2001) adduce evidence that ethnic groups are treated as biological “species” in the human brain.

The Right Kind of List

We’ve discussed six intuition generators: care/harm, proportional fairness, dominance, autonomy, purity/disgust, and group loyalty.  

Is our list too long? So many mechanisms to explain human social behavior would seem to violate parsimony. Are we adorning our theory with epicycles? Are we overfitting our model?

In fact, I affirm the massive modularity hypothesis: that the human brain contains dozens of mental modules, each of which have distinctive phylogeny, ontogeny, anatomy, behavioral profile, and ecological motivation. I have not conjured these entities to explain morality. Rather, I am drawing a small subset from my overarching project to describe the architecture of mind.

Implications for the Norm System

Recall the the moral/conventional distinction:

  • Conventional judgments (should / should not) are intuitions of socially appropriate behavior, and associated with embarrassment.
  • Moral judgments (good / evil) are also judgments about behavior, but more associated with anger, inflexibility, condemnation, and guilt.

Jonathan Haidt claims that these generators are responsible for moral intuitions. But the above generators also underlie the structure of our conventional norms. After all, there are plenty of mildly disrespectful behaviors that even the most conservative people would not describe as evil.

We have identified dozens of other specialized modules in the human brain. Why is e.g.,  feeling of knowing (recognition memory) not on our list? Because there were no biocultural pressures to integrate it with the norm acquisition and norm evaluation systems. We call our six modules social intuition generators because they have become intertwined with our normative machinery.

moral foundations_ module view

An Explanation of American Politics

People are genetically and environmentally disposed to respond to certain generators more strongly than others. Social matrices encode how many stimuli activate a given social intuition, and how strongly. 

People with similar matrices tend to gravitate towards similar political parties. When you measure the social matrices of American citizens, you can see large differences between the social intuitions of Democrats and Republicans (Graham et al, 2009).

moral foundations_ social matrices by political party (2)

These differences in social matrices explain much of American politics.

  • Why do Democrats praise entitlements, but Republicans denounce them? Because Democrats heavily emphasize Care for the poor, whereas Republicans more strongly reverberate to questions of Proportional Fairness (moral hazard).
  • Why are Democrats more skeptical of patriotism than their Republican counterparts? Perhaps because they respond to Loyalty to country less.
  • How can both groups claim to value Proportional Fairness? There are two competing explanations for poor outcomes: environmental (bad luck) or personal (poor character). Liberals tend to focus on the former, conservatives on the latter.
  • How can both groups claim to value Autonomy? For liberals, Autonomy responds ethnic oppression: perceived injustices done in the name of one’s tribe. The foundation is expressed as group symmetry. For conservatives, Autonomy responds to government oppression: perceived injustices in the form of taxes, nanny state, and regulations. The foundation is expressed as political liberty.

Looking Forward

Moral Foundations Theory is the invention of Jonathan Haidt, who introduces the concept in his excellent 2012 book The Righteous Mind: Why Good People are Divided by Politics and Religion. You can explore your moral matrix at

This post is 90% exposition, and 10% innovation. I innovate in the preceding two sections, by a) linking the six “taste buds” to mental modules that modulate inputs to the normative system, and b) broadening its reach to conventional (non-moral) norms.

In his book, Haidt makes the case the conservatives are more ethically sophisticated, because their moral judgments respond to a larger number of taste buds. But besides appealing to the ethos of Durkheim and Burke, Haidt doesn’t investigate the normative status of the social intuition generators in sufficient detail.

Here are three questions I would like to explore, at some point:

  • What is the normative status of e.g., disgust? If we could dampen or amplify disgust reactions in human beings, what would be the end result?
  • Social matrices encode different modes of existence that are hard to comprehend unless they are lived. What sort of social matrices are underexplored? Does there exist entirely novel modes of existence that we simply have not yet tried out?
  • What does the moral matrix of a successful metamorality look like? How do we promote positive outcomes when moral communities must live with one another?

Related Resources

  • Boehm (2012). Hierarchy in the Forest: The Evolution of Egalitarian Behavior
  • Haidt (2012). The Righteous Mind: Why Good People are Divided by Politics and Religion.
  • Graham et al (2009). Liberals and conservatives rely on different sets of moral foundations.
  • Cushman et al (2012). Simulating murder: the aversion to harmful action
  • GilWhite et al (2001). Are ethnic groups biological “species” to the human brain? Essentialism in our cognition of some social categories