Cooking and the Hominid Revolution

Part Of: Anthropogeny sequence
Content Summary: 2100 words, 21 min read

The Universality of Cooking

Cooking is a human universal. It has been practiced in every known human society. Rumors to the contrary have never been substantiated. Not only is the existence of cooked foods universal, but most cuisines feature cooked foods as the dominant source of nutrition.

Cooking_ A Human Universal (1)

Raw foodists comprise a community dedicated to consuming uncooked food. Of course, compared to historical hunter-gatherers, modern raw foodists enjoy a wide variety of advantages. These include:

  1. Elaborate food preparation (pounding, purees, gently warming),
  2. Elimination of seasonal shortages (supermarkets)
  3. Genetically enhanced vegetables with more sugar content and fewer toxins.

Despite these advantages, raw foodists report significant weight loss (much more than vegetarians!). Further, raw foodists suffer from increasingly severe reproductive impairments, which have been linked to not getting enough energy.  

Cooking_ Consequences of Raw-Foodism (1)

Low BMI and impaired reproduction are perhaps manageable in modern times, but are simply unacceptable to hunter-gatherers living at subsistence levels.

The implication is clear: there is something odd about us. We are not like other animals. In most circumstances, we need cooked food.

The Energetics of Cooking

Life exists to find energy in order to make more copies of itself. Feeding and reproduction are the twin genetic imperatives.

Preferences are subject to natural selection. The fact that we enjoy cooked food suggests that cooking provides an energy boost to its recipients. The raw-foodist evidence hints towards this conclusion as well. But there is also direct evidence in rats that cooking increases energy gains.

In the following experiments, rat food was either processed/pounded, cooked, neither, or both. After giving this diet over the course of four days, rats in each condition were weighed.

Cooking_ Energy Benefits of Cooking (1).png

For starches (left) and meat (right), cooking is by far more effective at preventing weight loss and promoting weight gain. Tenderizing food can sometimes help, but that technique pales in comparison to cooking.  

The above results were taken from rats. But similar results have replicated in calves, lambs, piglets, cows, and even salmon. It seems to be universally true that cooking improves the energy derived from digestion, sometimes up to 30%.

How does cooking unlock more energy for digestion?

First, denaturation occurs when the internal bonds of a protein weaken, causing the molecule to open up. Heat predictably denatures (“unfolds”) proteins, and denatured proteins are more digestible because their open structure exposes them to the action of digestive enzymes.

Besides heat, three other techniques promote denaturation: acidity, sodium chloride, and drying. Cooking experts constantly harp on these exact techniques, because it aligns with eating preferences.

Second, tender foods is another boon to digestion, because they offer less resistance to the work of stomach acid.  If you take rat food, and inject air into the pellets, that does not augment denaturation. Nevertheless, softening food in this way improves the energy intake of the rat.

Cooking does have negative effects. It can cause a loss of vitamins, and give rise to long-term toxic molecules called Maillard compounds, which are linked to cancer. But from an evolutionary perspective, these downsides are overshadowed by the impact of more calories. In subsistence cultures, better fed mothers have more, happier, and healthier children. When our ancestors first obtained extra calories by cooking their food, they and their descendants past on more genes than others of their species who ate raw.

A Brief Review of Human Evolution

The most recent common ancestor of humans and chimpanzees lived 6 mya (million years ago). But the first three million years of our heritage are not particularly innovative, anatomically. The australopiths were essentially bipedal apes. They could walk comfortably, but retained their adaptations for tree living as well. There is some evidence that australopiths acquired food from a new source: tubers (the underground energy storage system of plants).

Climate change is responsible for the demise of the australopiths. Africa began getting dryer about 3 million years ago, making the woodlands a harsher and less productive place to live. Desertification would have reduced the wetlands where Australopiths found fruits, seeds, and underwater roots. The descendents of Australopithecus had to adapt their diet.

The paranthropes adapted by promoting tubers (underground storage organs of plants) from backup to primary food. In contrast, the habilines (e.g., Homo Habilis) took a different strategy: meat eating. These creatures inherited tool making from the late australopiths (Mode 1 tools, the Oldawan industry- was discovered in Ethiopia 2.6 mya), and used these tools to scrape meat off of bones). The habilines are more ecologically successful, and lead to:

  • 1.9 mya: The hominids (e.g., Homo erectus/ergastor) with significantly larger brains and near-modern anatomies.
  • 0.7 mya: The archaic humans (e.g., Homo Heidelbergensis) appear, who eventually give rise to the Neanderthals, Denisovans, and us.
  • 0.3 mya The modern humans (e.g., Homo Sapiens) emerge out of Africa, and completely conquer the globe.

Here is a sketch of how our body plans have changed across evolutionary time:

Cooking_ Hominin Anatomy Comparison

And here is a high-level summary of the anatomical and behavioral increments:Anthropogeny_ Anatomical and Cognitive Cladistics (1)

Explaining Hominization

The transition from habiline to hominid deserves a closer look. A number of paradoxes shroud the emergence of H. erectus:

  1. Digestive Apparati. The hominid diet appears to be mainly meat and tubers. Both require substantial jaw strength and digestive apparati. Yet the Homo genus features a dramatically reduced digestive apparatus. How was smaller mouths, weaker jaws, smaller teeth, small stomachs, and shorter colons an adaptive response to eating meat and starches?
  2. Expensive Tissue. Australopiths brain size stayed relatively constant at 400 ccs (10% of resting metabolism). Hominid brains began to grow. This transition ultimately yielded a 1400 cc brain (20% of resting metabolism) in archaic humans. How did the hominids find the calories to finance this expansion?
  3. Time Budget. The above anatomical features of hominids are geared towards endurance running, which suggests that their lifestyle involved persistence hunting. Chimps have about 20 minute intervals in between searching for & chewing food. Thus, chimps can only afford to spend 20 minutes hunting before giving up. How did hominids perform the risky behavior of persistence hunting, which consumes 3-8 hours of time?
  4. Thermal Vulnerability. As part of their new hunting capabilities, hominids became the naked ape (with a new eccrine sweat gland system to prevent overheating). But Homo Erectus also managed to migrate to non-African climates such as Europe. How did these creatures stay warm?
  5. Predator Safety. Hominids lost their anatomical features for arboreal living, which suggests they slept on the ground. Terrestrial sleeping is quite dangerous on the African savannah. How did hominids avoid predation & extinction?

All of these confusing phenomena can be explained if we posit H. erectus discovered the use of fire, and its application in cooking:

  1. Digestive Apparati. As we have seen, the primary role of cooking is to “externalize digestion”, and to increase the efficiency of our digestive tract. Cooked meat and starches are incredibly less demanding to process than their raw alternatives. This explains our reduced guts. By some estimates, the decrease in digestive tissue corresponds with a 10% energy savings by our hominid ancestors.
  2. Expensive Tissue. Cooking increases the metabolic yield of most foodstuffs by ~30%. For reference, a 5% increase in ripe fruit for chimpanzees reduces interbreeding interval (time between children) by four months. 30% is an absurdly large energy gain, enough to “change the game” for hominids.
  3. Time Budget. Cooking freed up massive amounts of time otherwise spent chewing. Chimpanzees can take 4-7 hours per day chewing; humans only need one hour per day. This frees up massive amounts of time, which can be used for e.g., hunting.
  4. Thermal Vulnerability. It is very difficult to explain a hairless Homo Erectus thriving on the colder Asian continent without control of fire.
  5. Predator Safety. It is very difficult to explain how hominids were not preyed upon to extinction without fire to identify & deter predators. Hadza hunter-gatherers comfortably sleep through the night, typically by taking turns “on watch” while the others rest.

Cooking_ Overall Argument (3)

The Archaeological Record

We are positing that hominids learned to create and controlling fire 2 mya. Is that a feasible hypothesis?

Habilines had learned how to create stone tools 2.6 million years ago. By the time of the hominids, techniques to create these tools had persisted for 600,000 years. So it is safe to say that our ancestors were able to retain useful cultural innovations.

Independent environmental reasons link fire-making with H Erectus. The Atlas mountain range is the most likely birthplace of this species, and this dry area fires triggered by lightning are an annual hazard. Hominins living in such environments would be more intimately familiar with fire than those with less combustible vegetation zones.

Hominids would have seen sparks when they hit stones together to make tools. But the sparks produced by many kinds of rock are too cool to catch fire. However, when pyrites (a fairly common ore) are hit against flint, the results are used by hunter-gatherers to reliably produce fire. The Atlas mountain range is renowned for being exceptionally rich in minerals:

Why is Morocco one of the world’s great countries for minerals? No glaciers! Many of the world’s most colorful minerals are found in deposits at the surface, formed over time by the interaction of water, air and rock. Glaciers remove all of that good stuff (as happened in Canada recently, geologically speaking) –  and with no recent glaciation, Morocco hosts many fantastic occurrences of minerals unlike any in parts of the world stripped bare during the last Ice Age.

Since this mountain range contains pyrites, early hominids could have found themselves inadvertently making fire rather often.

Once it is created, fire is relatively easy to keep going. And it does not take much creativity to stick food a fire. Moreover, modern-day chimps prefer cooked food over raw; it is hard to imagine hominids finding cooked food distasteful. All of these considerations suggest an early control of fire is at least plausible.

We can consult the archaeological record to see record of man-made fire (i.e., hearths). This is bad news for the cooking hypothesis! There is strong evidence for hearths dating back to 800 mya and the advent of archaic humans. Before then, there are six sites that seem to be hominid hearths; but these are not universally acknowledged as such.

Cooking_ Archaeology Evidence (1)

But absence of evidence isn’t evidence of absence, right?

No! That idiom is wrong. Silence is evidence of absence. It’s just that the strength of the evidence depends on the nature of the hypothesized entity.

  • If you think an unidentified planet orbits the Sun, a lack of evidence would weigh heavily against the hypothesis.
  • If you think an unidentified pebble orbits the Sun, a lack of evidence doesn’t say much one way of the other.

Wrangham argues that evidence of hearths are more fragile than e.g. fossils, and points to facts like there are zero hearths recorded for modern humans during European “ice ages” – but we know these must have existed. It is possible that the contested hearth sites will ultimately be vindicated, and that we just can’t see much evidence.

Despite these claims about evidential likelihood, the silence of the archaeological record is undeniably a significant objection to the theory.

Weighing The Evidence

Is the cooking hypothesis true? Let us weigh the evidence, and contrast it with alternative hypotheses.

The most plausible alternative hypothesis is that archaic humans H. Heidelbergensis discovered cooking. But the emergence of that species involved an increase in brain size, and more sophisticated culture & hunting technology.  Neither adaptation seems strongly connected to cooking. In contrast, the H. Erectus adaptations would have all been strongly affected by cooking. 

Moreover, alternative hypotheses must still answer the five paradoxes of hominization:

  1. Digestive Apparati. Why did hominids evolve smaller mouths, weaker jaws, smaller teeth, small stomachs, and shorter colons?
  2. Expensive Tissue. How did the hominids find the calories to finance more brain tissue?
  3. Time Budget. How could hominids afford spending 3-8 hours per day engaged in the risky strategy hunting?
  4. Thermal Vulnerability. Hominids also managed to migrate to non-African climates such as Europe. How did these creatures stay warm?
  5. Predator Safety. Hominids slept on the ground. How did they avoid predation?

The habilines ate meat. It is unclear how they did so (hunting or scavenging), but we have strong evidence that they did. Meat is a much higher quality food than tubers (cf. paranthropes) or fruit (cf. chimpanzees). The meat-eating hypothesis argues that meat eating was the primary driver of hominization.

Meat-eating resolves the Expensive Tissue paradox (meat allows for brain growth) and Digestive Apparati (carnivores are known to have smaller guts). But it doesn’t address why a meat-eater would develop smaller canines. And it struggles to explain how the reduction in gut size is compatible with the tuber component of the hominid diet. And what about time budget, thermal vulnerability, and predator safety? The meat eating hypothesis fails to address these paradoxes entirely.

Which is more likely to occur in the next twenty years: undisputed evidence for early control of fire, or an alternate theory that resolves all five hominization paradoxes?

My money is on the former.

References

  • Wrangham (). Catching Fire: How Cooking Made Us Human
  • Aiello & Wheeler(1995). The expensive tissue hypothesis: the brain and the digestive system in primate and human evolution.
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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 yourmorals.org.

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

The Evolution of Disgust

Part Of: Affective Neuroscience sequence
Content Summary: 1400 words, 14 min read.

Introduction

Why did disgust evolve? Why does it play a role in morality? Should it?

One of the best ways to understand an emotion is to build a behavioral profile: a list of its responses (outputs) and elicitors (inputs).

Disgust Responses

One of the striking features of disgust is how diverse its set of responses. These include an affect program:

  • Gape face. This is characterized by a nose wrinkle, extension of the tongue, and wrinkle upper brow.
  • Feeling of nausea. In fact, the physiological signature of intense disgust closely matches physical nausea.
  • A withdrawal reflex. This reflex need not be physical retreat, but can also yield motivation to remove the offending object.

But disgust also produces an inferential signature:

  • Sense of oral incorporation. That is, the subjective feeling that the offending object is already in one’s mouth.
  • Offensiveness tagging. Even after the object has been removed, it will continue to be treated as offensive indefinitely.
  • Asymmetric transmission logic. See the law of contagion: a clean object that touches something gross is contaminated, but not vice versa.

Disgust Elicitors

Even more diverse than its outputs, the elicitors of disgust include cultural universals, including:

  • Organic decay.
  • People and objects associated with illness
  • Compromised body envelope. These include: cuts, gashes, lesions, or open sores.
  • Substances that have left the body. These include feces, vomit, spit.  

Swallowing the saliva that is currently in your mouth is innocuous, but even imagining yourself drinking a glass of spit (even if it is (was?) your own, is disgusting. These last two elicitors are body perimeter tracking: they not only police the boundaries of the body in peripersonal space, but also seem to enforce a no re-entry policy: anything that exits or becomes detached triggers it.

There exists another suite of elicitors that are culturally tuned

  • Specific foods.  Some foods are deemed disgusting even when they have never been tried (e.g., liver).
  • Specific living animals. These can include: flies, maggots, worms, rates, lice, tics, slugs, snails, and spiders…
  • Specific sexual practices. These can include: homosexuality, pedophilia, bestiality, necrophilia, …
  • Specific morphological signatures. Deviations from bodily normality, however that is construed in a particular culture. These can include: the elderly, disabled, little people, …

It is worth emphasizes that disgust over sexual practices and morphological signatures varies widely across cultures and across individuals. For example, ancient Greece mostly didn’t find homosexuality disgusting but 20th century Americana mostly did.

Finally, people comprise another category of elicitors.

  • Moral transgressors. These can include: murderers, rapists, …
  • Members of an out-group. These can include: untouchable caste, Jews (in Nazi Germany), …

Neuroscientific data suggest that, when people are deemed sufficiently disgusting, brain areas associated with mindreading become deactivated. This is likely the neural basis of dehumanization.

The Entanglement Thesis

Taken together, here is the behavioral profile of disgust:

disgust_ behavioral profile

Puzzle: Why should the sight of a person with leprosy evoke a gape face and a feeling of nausea? Leprosy has nothing to do with digestion.

Solution: Disgust is a kludge! It is the unholy merger of two separate systems.

Poison monitoring is a faculty of the digestive system. It evolved to regulate food intake and protect the gut against ingested substances that are poisonous or otherwise harmful. It was designed to expel substances entering the gastrointestinal system via the mouth. It also acquires new elicitors very quickly.

Infection avoidance is a faculty of the immune system. It evolved to protect against infection from pathogens and parasites, by avoiding them. Not specific to ingestion, but serves to guard against coming into close physical proximity with infectious agents. This involves avoiding not only visible pathogens and parasites, but also places, substances and other organisms that might be harboring them.

Any theory of disgust should explain the unity of responses to disgust. Here is how entanglement theory does it:

  • Poison monitoring produces the affect program. Gape face, nausea and withdrawal all serve digestive (and not immunological) purposes.
  • Infection avoidance produces (most of) the inferential signature. The tendency to monitor disgusting things even when not immediately exposed, and the asymmetric logic of contamination, make perfect sense when tracking the spread of parasites.

Any theory of disgust should explain the diversity of elicitors of disgust. Here is how entanglement theory does it:

  • Poison monitoring is sensitive to certain foods (namely, those that are associated with toxicity)
  • Infection avoidance explains the aversion to certain living animals (flies are more likely to carry disease than dogs), apparently disease-infected substances, to certain sexual practices (sexual practices can bring increased risk of disease) and morphological deviations (e.g., violates of facial symmetry correlate with parasites). It also explains the general tendency for disgust to monitor the body perimeter: which is, after all, how pathogens can enter the body!

Any theory of disgust should explain cultural variation of the elicitors. Here is how entanglement theory does it:

  • The poison monitoring system is very quick to learn features the Garcia effect: one-shot learning.
  • In women, aversion to deviant sexual practices (and not other forms of disgust) vary with where they are in the ovulation cycle.

disgust_ entanglement thesis

Besides the increase in explanatory power, phylogenetic and ontogenic data also support the independence of these two systems:

  • Researchers disagree whether disgust is unique to humans, or whether homologies exist in the animal kingdom. Both are right: animals show clear signs of the existence of both systems but the systems are expressed separately.
  • Ever wonder why children don’t seem to mind disgusting objects & behaviors? It is because poison monitoring appear very early (within first year of life) but infection avoidance emerges significantly later.

The Evolution of Disgust

Why should the poison avoidance and pathogen monitoring have become entangled in the course of human evolution? Why didn’t poison avoidance become entangled with e.g., FEAR instead?

First, the two systems both care about digestion. Food intake can bring both poison and pathogens into the body, and as such it is monitored by both systems.

Why did entanglement only happen in humans, specifically? Compared to other primates, early hominids adopted a unique lifestyle, that combined scavenging with a nascent ultrasociality. These two characteristics put enormous adaptive pressure on the pathogen avoidance system to innovate.

Perhaps the most important reason for entanglement has to do with signaling. As hominids began to increasingly emphasize social cooperation, there became a need to communicate pathogenic information. Before the emergence of language, the pathogen avoidance module had an inferential signature – but how to communicate this contamination tagging information with others? The functionally-overlapping toxin monitoring system had a clearly visible output: the gape face. Plausibly, the two modules merged such that pathogen monitoring system could co-opt gape face to communicate. We can call this the gape face as signal theory.

My Take on the Theory

The theory I have presented here was developed by Daniel Kelly’s book Yuck! The Nature and Moral Significance of Disgust. The theory strongly complements Mark Schaller’s work on the behavioral immunity system. The overlap between these two researchers will become clear next time, when we turn to the social co-optation of the disgust system.

I personally find the entanglement thesis (the merger of toxin monitoring and pathogen avoidance systems) compelling, given its tremendous explanatory power outline above.

Despite accepting the overall architecture, Kelly’s theory for why the architecture evolved (gape face as signal) strikes me as incomplete.

I also feel like this theory will remain incomplete until we discover how toxin monitoring and parasite avoidance are implemented in dissociable neurobiological structures (i.e., modules).

After the psychological mechanisms are mapped to their physical roots, we could attempt to integrate our knowledge of disgust with other systems:

  • What is the relationship of disgust to the generalized stress response? Stress & the immune systems co-evolved to share the HPA axis, after all.
  • How is disgust implemented in the microbiome-gut-brain axis, which also has links to both the digestive system (enteric nervous system) and the immune system (e.g., leaky gut)?
  • How does the MGB axis differentially produce both disgust and other social phenomena like anxiety?

Open questions are exciting! To me, it suggests a clear research program where we can start integrating our newfound theory of disgust into the broader picture of visceral processes (the hot loop).

Takeaways

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.

Related Resources

  • Kelly (2013). Yuck! The Nature and Moral Significance of Disgust.
  • Fessler & Haley (2006). Guarding the Perimeter: the inside-outside dichotomy in disgust and bodily experience.

Confabulation: saying more than we can know

Part Of: Demystifying Sociality sequence
Content Summary: 1500 words, 15min read

Anosognosia

It is unfortunate to experience illness. It is strange to fail to recognize illness within oneself. Anosognosia is the name for this inability. A few examples:

Example 1. In a letter to his friend Lucilius, Seneca (40 CE) described a woman who obstinately denied her blindness.“….You know that Harpestes, my wife’s fatuous companion, has remained in my home as an inherited burden….This foolish woman has suddenly lost her sight. Incredible as it might appear, what I am going to tell you is true: She does not know she is blind. Therefore, again and again she asks her guardian to take her elsewhere because she claims that my home is dark…..It is difficult to recover from a disease if you do not know to be ill….”. 

Example 2. After a right-hemisphere stroke, she lost movement in her left arm but continuously denied it. When the doctor asked her to move her arm, and she observed it not moving, she claimed that it wasn’t actually her arm, it was her daughter’s. Why was her daughter’s arm attached to her shoulder? The patient claimed her daughter had been there in the bed with her all week. Why was her wedding ring on her daughter’s hand? The patient said her daughter had borrowed it. Where was the patient’s arm? The patient “turned her head and searched in a bemused way over her left shoulder”. 

Spend enough time with these patients, and it becomes clear that their problem is not cognitive dissonance. No, the delusion has a much deeper, subterranean, hold on their mental lives.  These patients freely generate explanations for their illness-related behavior (“I can’t walk around because the house is dark”, “The unmoving arm isn’t mine, it is my daughters”). These explanations are not examples of dishonesty. They are genuine perceptions of a misfiring mind. The word for these honest lies is confabulation.

Confabulation_ Comparing to Dishonesty (1)

If you’re anything like me, you’ll find such epistemic fences a bit unsettling. Is it possible our entire species is entertaining a similar delusion that increases biological fitness? Do we actually have four fingers but are collectively convinced that little fingers exist?

Split Brain Patients

The vertebrate brain has two hemispheres. Some neural functions are bilateral: visual processing occurs in both right and left hemisphere (one per eye). Other functions are unilateral: language processing is usually left-lateralized (with the exceptions tending to be left-handed). The advantages & disadvantages of lateralization of brain function is an active research area.

In neurotypical animals, there exist traverse fibers (commissures) which integrate information between the hemispheres. The corpus callosum is the overwhelmingly dominant bridge between hemispheres:

  • Corpus Callosum: 250 million fibers
  • Anterior commissure: 0.5 million fibers
  • Posterior commissure: 0.5 million fibers
  • Habenula commisure: 0.1 million fibers

Split brain patients are those that have had their corpus callosum severed. These patients tend to exhibit selfhood fracturing: each hemisphere constitutes a largely autonomous entity with its own beliefs and desires.

Present the left hemisphere with a picture of a chicken claw, and the right with a picture of a wintry scene. Now show the patient an array of cards with pictures of objects on them, and ask them to point (with each hand) something related to what they saw. The hand controlled by the left hemisphere points to a chicken, the hand controlled by the right hemisphere points to a snow shovel. So far so good.

But what happens when you ask the patient to explain why they pointed to those objects in particular? The left hemisphere is in control of the verbal apparatus. It knows that it saw a chicken claw, and it knows that it pointed at the picture of the chicken, and that the hand controlled by the other hemisphere pointed at the picture of a shovel. Asked to explain this, it comes up with the explanation that the shovel is for cleaning up after the chicken. While the right hemisphere knows about the snowy scene, it doesn’t control the verbal apparatus and can’t communicate directly with the left hemisphere, so this doesn’t affect the reply. The patient instead confabulates.

What did ”the patient” think was going on? This is a wrong question. Once you know what the left hemisphere believes, what the right hemisphere believes, and how this influences organism behavior, then you know all that there is to know.

Gazzaniga has described this propensity of patients to confabulate reasons for the behavior of the right brain as the left-brain apologist. The left hemisphere functions as an interpreter, a lawyer, a press secretary:: it justifies behavior to make the organism look good. V.S Ramachandran, drawing on observations that right-brain lesions disproportionately produce delusions, claims the existence of a right-brain revolutionary. It is the failure some module in the right hemisphere that causes anosognosia: the left-brain apologist to go unchecked: confabulation exacerbated by delusion.

Confabulation in Neurotypicals

We have so far explored confabulation in patients with brain damage. Do neurotypical, everyday people produce “honest lies”?

We confabulate all the time.. We just don’t realize that we are.

In Telling More Than We Can Know: Verbal Reports on Mental Processes, Nisbett & Wilson (1977) review hundreds of studies, across dozens of disciplines. Their evidence admits a theme: people’s attempts to explain their behavior is almost always unhelpful in identifying the important factors influencing their decisions. Let me briefly review four example findings.

Study 1: Insufficient Justification.

Zimbardo et al (1969) ask participants to accept a series of painful shocks while performing a learning task. Participants were split into two groups:

  • Adequate Justification (“nothing will be learned unless shocks administered again”)
  • Inadequate Justification (“I’m curious to see what happens”)

Who suffers less?

→ The Inadequate Justification group. This group learns much more quickly, and admit lower galvinic skin response (lower “fight or flight”).

Why do they suffer less?

→ These people were given a poor justification for continuing, and yet they continued anyway. To explain their own behavior, they generate intrinsic motivation for continuing. (As an aside, this phenomenon is similar to the overjustification effect).

Do they know that they suffer less?

→ No! Subjective reports of pain were the same across groups.

Study 2: Attribution Effect

Storms & Nisbett (1970) ask insomnia-suffering participants to sleep under observation. Participants were split into two groups:

  • Arousal Attribution: placebo given, claimed to cause restlessness, alertness
  • Control: no placebo administered

Who falls asleep more quickly?

→ Arousal Attribution group (28% faster).

Why do they fall asleep more quickly?

→ Attribution of restlessness to placebo, rather than cognitive factors.

Do they know why they fall asleep more quickly?

→ No! More than 80% of patients would not attribute sleep improvement to pill, even after the experiment being explained to them.

Study 3: Counterattitudinal Advocacy

Bem & McConnell (1970) ask participants for their view on a political topic. Then ask they write an essay against their own view. Participants were split into two groups:

  • Coercion: bribed to write the essay
  • Freedom: led to believe they had a choice

Who changes their position after writing the essay?

→ Freedom group.

Why do they change?

→ Difficult to explain writing that essay, unless they wanted to.

Do they know that they changed their position?

→ No! In contrast to the Coercion group which had accurate memories, those whose opinions had changed failed to remember their previous position.

Study 4: Choice Blindness

Johannson et al. (2005) ask participants to evaluate which of two female faces was more attractive. Researchers then hand subjects the face they had chosen, asking them to explain the motives behind their choice. Participants were split into two groups:

  • Switch: used a sleight-of-hand trick to switch the photos, showing viewers the face they had not chosen.
  • Control: show the face they had chosen

Does the Switch group notice the change?

→ Most don’t. ⅔ of participants believe they had chosen the other face.

Did those who didn’t notice explain of their (non-)choice?

→ Without missing a step. They happily explained why they preferred the face they had actually rejected, inventing reasons like “I like her smile” even though they had actually chosen the solemn-faced picture.

Putting It All Together

Confabulation is “honest lying”: communicating an untruth, while earnestly believing in its veracity.

  • Anosognosia patients cannot admit that they are paralyzed. When asked to explain their inability to move, they confabulate answers.
  • Split brain patients similarly confabulate explanations for the behavior of the non-linguistic right hemisphere.
  • Confabulation is not merely a medical curiosity. Confabulation is everywhere: most self-reports are utterly useless. Some evidence includes:
    1. Insufficient Justification: people didn’t notice when they were suffering less
    2. Attribution Effect: people failed to understand the reason why they slept better
    3. Counterattitudinal Advocacy: after people change their minds, they fail to remember they ever thought differently
    4. Choice Blindness: once tricked into thinking they chose something different, people are happy to explain their reasons.

Confabulation_ Evidence Overview

Why do human beings confabulate so often? How can we be such utter strangers to ourselves?  We shall explore these questions next time. Until then!

The Construction of Body Status

Part Of: Neuroeconomics sequence
Content Summary: 800 words, 8 min read

Connection To Philosophy of Well-being

What is well-being?

Philosophers have put forward three theories.

  • Hedonic Theory. Well-being is experiencing pleasure.
  • Desire Fulfillment Theory. Well-being is achieving your goals.
  • Objective List Theory. Well-being is living an objectively good life.

In this post, we ask “does the brain have any incentive to compute biological measures of well-being? If so, what would this data structure be used for?”

Well-being is Body Status

Everyone agrees that the following are true about well-being:

  1. Well-being is sensitive to variables of body status. Instantaneous well-being is less if an animal is in pain, other things being equal.
  2. Well-being responds to many divergent factors (e.g., both pain and hunger reduce instantaneous well-being).

But there is only one biological apparatus that satisfies these properties:

Proposition 1. Well-being is body status, constructed by regulatory processes.

In 1925, Walter Cannon formulated homeostasis, which posits the body striving to maintain internal variables essential for life. For example, the body measures its own body temperature. If it is too hot or cold, a negative feedback process will initiate actions to bring the variable back into its optimal value.

homeostasis (2)

The body tracks many more variables besides body temperature. These variables together constitute a representation I will call body status:

Wellbeing Biology- Healthy Organism Body Status (2)

Body status representations play a key role in the biological construction of personal identity and subjectivity. We will return to this topic at another time.

Desire from Body Status

Markov Decision Process (MDPs) are a lens through which we can interpret behavior. An MDP contains states, actions, and a reward signal. The organism selects a policy \pi such that the states encountered maximize the reward signal.

mdp basics

Within the brain, the basal ganglia implements two data structures which together generate motivation:

  • A policy 𝝅 which maps states to actions, S → A.
  • A value function V(s) which represents expected reward.

Reinforcement learning theory is silent on the biological substrate of the reward signal. But to us, the solution is clear:

Proposition 2.  Reward is derived from the body status representation.

Body Status- Construction of Reward Signal (1)

This is one mechanism by which low body temperature is corrected. Body status deviations elicit a reward signal that prompt “cold” motor desires (e.g., shivering). In contrast, notice that “hot” visceral desires (e.g., blood vessel constriction) are constructed directly, not implemented by the basal ganglia.

Hedonics from Body Status

There are two liking systems in the brain:

  1. Hedonics is a global measure of pleasure and pain. It summarizes body state information.
  2. Valence is an object-specific judgment of value. Valence usually correlates with desire: we approach things that are pleasant, and avoid things that are unpleasant.

Yet drug addicts often reach the point where drug consumption is unpleasant, yet they pursue a fix regardless. Wanting and liking are dissociable. Why? Because they are implemented by different neurochemical systems (phasic dopamine and opioids, respectively).

Body status is not only used to behaviorally motivate. In my view, it also tags perceptual data with information about its visceral relevance.  This includes the two primary affective dimensions:

  • Object salience (“does this merit attention, further computation”)
  • Object valence (“is this safe to approach”)

Body Status- Tagging for Visceral Relevance (1)

So we have arrived at our next thesis:

Proposition 3. Hedonics and valence are derived from body status representation.

Philosophers debate whether well-being is best attributed to pleasure/pain or desire. But body status is used to construct both of these phenomena. This gives us reason to believe that the philosophical theories of hedonism and desire fulfillment can be unified.

The Socialification of Body Status

Across the course of natural history, certain animals have become increasingly social, able to interact more meaningfully with their conspecifics.

Three important social adaptations were:

  • In mammals, social status. Animals track their standing in the group.
  • In primates, social inclusion. Group living made possible by e.g., exchange of favors.
  • In hominids, social reputation. An prosocial alternative to power, independent of the dominance hierarchy.

How might a biological organism introduce these new behavioral repertoires? A simple way to do it might be to extend body status to incorporate social variables of interest:

body status socialification

Proposition 4. Body status was extended to support novel social behaviors.

This proposition lends a biological perspective why social ostracization is so painful, and elicits physiological distress directly comparable to e.g., evading predation.

This socialification hypothesis is more speculative than my other three propositions. How might we go about evaluating whether it is true?

Recall that body status is represented by an overlapping set of neurochemical networks, whose main connecting hub is the hypothalamus. If Proposition 4 is true, we would expect to find new chemical systems uniquely responsive to these proposed dimensions.

I suspect these connections will be established rather quickly. We already possess several extremely suggestive lines of evidence. See, for example, Hennessy et al (2014). Sociality and sickness: have cytokines evolved to serve social functions beyond times of pathogen exposure?

Takeaways

Today, I presented the following ideas:

  • Proposition 1. Well-being is body status, constructed by regulatory processes.
  • Proposition 2. Desire is derived from body status representation.
  • Proposition 3. Hedonics and valence are derived from body status representation.
  • Proposition 4. Body status was extended to support novel social behaviors.

Until next time.

The Relational Sphere Hypothesis

Part Of: Demystifying Sociality sequence
Followup To: The Three Spheres of Culture
Content Summary: 1700 words, 17 min read

A Theory of Relationship Dynamics

How can we make sense of social life? Let’s start by considering a simple cup of coffee.  

  1. In my own house, I can just help myself to as much as I want, sharing with others in the framework of “what’s mine is yours.”  
  2. Or my friend can get me a cup of coffee in return for the one I got for him yesterday, so we take turns or match small favors for each other.
  3. At Starbucks, I buy my coffee, using price and value as the framework.
  4. To my children, however, none of these principles apply. To them, coffee is something that only “big people” are allowed to drink: It is a privilege that goes with social rank.

What is true of a humble cup of coffee is true of the moral dilemmas surrounding major policy questions such as organ donation. Decisions have to be made, and there are again four fundamental ways to make them:

  1. Should we hold a lottery, giving each person an equal chance?  
  2. Should we somehow rank the social importance of potential recipients?
  3. Should we sell organs to the highest bidder?  
  4. Or should we expect everyone in a local community to give freely, offering a kidney to anyone group member in need?

(The above excerpt is from [FE] )

Relational Models Theory (RMT) proposes that these four social categories are exhaustive and culturally universal. Human interactions are complex, and typically use more than one of the above processes. But every relationship, in every culture, seems to be some combination of the following:

  • In Communal Sharing (Communality), people are viewed as equals oriented around some particular identity. This can include being in love, sports fans, and co-religionists.
  • In Authority Ranking (Dominance), people are situated in a hierarchy where superiors are deferred to, respected, and in some cases obeyed.
  • In Equality Matching (Reciprocity) people are interested in restoring balance, turn-taking, and making sure everyone is treated fairly. 
  • In Market Pricing (Exchange), relationships are governed by quantitative, utilitarian concerns such as prices, exchanges, or cost-benefit analyses.

We can use relational models to explain a wide swathe of social phenomena:

  • Some examples of norm violation are in fact category errors. For example, we would interpret a situation such as the price of our meal is two hours on dishwasher duty as a conflation of Market Pricing vs. Equality Matching.
  • Some (but not all) examples of taboo trade-offs are in fact category errors. The Finite Price of Human Life thesis feels counterintuitive because it pits our Market Pricing versus the sacred values held by Communality.
  • Humans often use indirect speech acts to reconcile relationship types with semantic content.Rather than saying e.g., “pick me up after work”, we often say things like, “If you would pick me up after work, that would be awesome”. While more verbose, the latter expression feels more polite because it is couched in a Communality frame, rather than signaling Dominance.

In addition to its explanatory reach, multiple strands of evidence come together in support of  Relational Model theory:

  • Factor analysis. If you ask people to describe their relationships, you can see whether your theory predicts statistical patterns in their responses. When RMT was compared with other taxonomies (and there are a lot of them), RMT starkly outperforms its competitors. 
  • Ethnographies. RMT was invented by anthropologist Alan Fiske to capture regularities he saw across different cultures. For example, he found examples of marriage treated as Dominance, as Market Pricing, etc – but never a fifth type. A number of cross-cultural studies indicate that the four relational models constitute a human universal.
  • Social errors. When people misremember a person’s name, it tends to be a person with whom they share the same relationship type. For example, if you flub the name of your boss, you are more likely to say the name of someone else in a position of authority over you.
  • Brain studies.  In the cortex, the default mode network is universally acknowledged to perform social processing. But within this specialized region, different subregions are activated when processing e.g., Communality vs Reciprocity relationships.

The Relational Sphere Hypothesis

Human societies can be conceived as operating in three spheres: markets, governments, and communities. The Cultural Sphere Hypothesis holds this trichotomy to be fundamental, and exhaustive of social space.

Relational Models_ Cultural Regime Dissociations (4)

There seems to be a relationship between the cultural spheres and relation models. But there are three spheres vs four models. What gives?

Things become more clear when we remember that market- based economies were invented during the Neolithic Revolution, with the dawn of agriculture. Before this inflection point in history, transactions took place with gift economies.

This suggests that the Market Pricing relational model is evolutionarily recent: before the invention of agriculture, it simply did not exist.

Relational Model Theory_ Models vs Spheres (3)

I call this particular mapping from relational models to cultural spheres the Relational Sphere Hypothesis (RSH). It is an intertheoretic reduction: it purports to be a significant join point between micro- and macro-sociality.

RSH predicts that three out of four relational models can be traced back to the birthplace of Homo Sapiens. Thus, we should expect predecessors for these relationship categories in primate societies! And we find precisely that:

  • Dominance models are expressed in the dominance hierarchy (where physical dominance slowly gave way to symbolic dominance).
  • Communality models are expressed in kin selection (where attachment to and care for relatives was slowly extended towards e.g. close friends).
  • Reciprocity models are expressed in reciprocal altruism (where increasingly large delays between favor-transactions became possible).

I have argued elsewhere that the dual-process models so popular in today’s moral psychology can be captured in the interactions between (cortical) propriety frames and (subcortical) social intuitions. These two systems comprise the building blocks of sociality. RSH dovetails nicely with this dual process account, as it perceives categories within these systems, each with its own distinctive logic:

rmt_categorization

With the exception of Sanctity, these subconscious social intuitions arguably exist in primates. For example, here is evidence that rhesus monkeys have strong intuitions about Fairness:

A New Kind of Social Network

The Relational Sphere Hypothesis can be further illustrated by social networks: graphs where nodes are individuals, and edges are relationships. These kinds of models are very common across many disciplines that study aggregate social phenomena; for example evolutionary game theorists. A social network may look something like this:

Relational Models_ Aggregated Social Networks

But relationships inhabit different categories. We can express this fact by coloring edges according to their relational model:

Relational Models_ Complete Social Network (2)

Note that some nodes (e.g. A and B) are connected by more than one color. This signifies that the relationship between A and B features both Communality and Dominance.

From this more complete picture of human relationships, we can derive our cultural spheres by examining the (mono-color) subgraphs:

Relational Models_ Social Network Subgraphs (2)

Sphere Evolution & Competition

Political, social, and economic institutions have dramatically changed across the course of human history. As we saw in Deep History of Humanity, the evolution of our species can be usefully divided into three time periods:

Relational Models_ Sphere Evolution (1)

 

The Sphere Competition Conjecture comprises a set of informal intuitions that relational models “competes for our attention”: gains in one sphere are often accompanied by losses in another.

Let me illustrate this conjecture with examples. 🙂

Social vs Economic spheres

  • The religious instinct is etched deeply into the hominid mind, and evidence for shamanic animism dates back to the advent of behavioral modernity. Modern religion is located squarely within the Social sphere. But what caused its institutionalization, the invention of the full-time religious specialist: the priest? Religious institutions were founded during the transition from gift economy to market economies. For the first time in history, material wealth mattered more in transactions than interpersonal reputation. With the Social sphere threatening to collapse, perhaps it is not a coincidence that it was at this moment in history that religion became more explicitly social.
  • Some existential philosophers argue that the industrial revolution, with its obscenely large increase in Economic productivity, has correlated with a weakening of Social values, as witnessed empirically by the rise of materialism. Perhaps the malaise and cynicism of postmodernity can be explained by the weakening of the ties of community.
  • The custom of tipping can be conceived as an organ of Sociality, that feels misplaced in today’s Market-oriented economy. This institution shows no signs of abating (for example, Uber recently rescinded its no-tipping policy). Perhaps the reason this Social technology persists, while others have disintegrated, is because tipping solves the principal agent problem: customer service is otherwise not factored into the price, because that information is not easily available to management.  
  • Product boycotts are another example of Social outrage affecting Economic markets.

Social vs Political.

  • Another important event in the history of religion is the transition to universal religions: where the concerns of the gods and the consequences of moral violations were imbued with an aura of the eternal. Anthropological evidence clearly suggests that universal religions succeeded because they facilitated larger group sizes.
  • Corruption is often treated as a political problem, but in fact bribery and collusion both require high amounts of social capital.
  • In American history, political partisanship has been most severe in the 1880s, and at present. Both then and now are periods of an intense drought of social capital. Further, participation in voting strongly correlates with vibrant community and civic life. We might conjecture that weaker communities are more vulnerable to partisanship infighting. This conjecture is aligned with the oft-cited observation that partisanship tends to correlate with moderates abandoning the political arena.

Economic vs Political.

  • Capitalist Peace Theory formalizes the observed inverse relationship between free trade and international conflict. On this hypothesis, one of the strongest predictors of war is resource acquisition, and the risk-benefit calculus changes (improves) substantially with the removal of tariffs.

Economic vs Political vs Social.

  • The Size of Nations Hypothesis is the idea that the size of nation (Political) is driven by two competing factors: larger nations are able to produce public goods more efficiently (Economic), but conversely their populations are more heterogenous and thereby less cohesive (Socially).

Some of the phenomena described above have been extensively studied by social scientists. However, to my knowledge, no extant models robustly capture the doctrine of relational model theory. Perhaps the next generation of formal models will do better.

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