Part Of: Demystifying Culture sequence
Content Summary: 1200 words, 12 min read
Recall that human beings have two different vehicles for learning:
- Individual Learning: using personal experiences to refine behavioral techniques, and build causal models of how the world works.
- Social Learning: using social interactions to learn what other people have learned.
Today, we will try to explain the following observations:
- Most cultural traditions have adaptive value.
- This value typically cannot be articulated by practitioners.
Why should this be the case?
Example 1: Manioc Detoxification
Consider an example of food preparation, provided by Joseph Henrich:
In the Colombian Amazon, a starchy tuber called manioc has lots of nutritional value, but also releases hydrogen cyanide when consumed. If eaten unprocessed, manioc can cause chronic cyanide poisoning. Because it emerges only gradually after years of consuming manioc that tastes fine, chronic poisoning is particularly insidious, and has been linked to neurological problems, paralysis of the legs, thyroid problems, and immune suppression.
Indigenous Tukanoans use a multistep, multiday processing technique that involves scraping, grating, and finally washing the roots in order to separate the fiber, starch, and liquid. Once separated, the liquid is boiled into a beverage, but the fiber and starch must then sit for two more days, when they can then be baked and eaten. Chemical analyses confirm that each major step in the processing is necessary to remove cyanogenic content from the root. 
Yet consider the point of view of a woman learning such techniques. She may never have seen anyone get cyanide poisoning, because the techniques work. And she would be required to spend about four hours per day detoxifying manioc. 
Consider what might result if a self-reliant Tukanoan mother decided to drop seemingly unnecessary steps from the processing of her bitter manioc. She might critically examine the procedure handed down to her from earlier generations and conclude that the goal of the procedure is to remove the bitter taste. She would quickly find that with the much less labor-intensive process of boiling, she could remove the bitter taste. Only decades later her family would begin to develop the symptoms of chronic cyanide poisoning.
Here, the willingness of the mother to take on faith received cultural practices is the only thing preventing the early death of her family. Individual learning does not pay here; after all, it can take decades for the effects of the poison to manifest. Manioc processing is causally opaque.
The detoxification of dozens of other food products (corn, nardoo, etc) are similarly inscrutable. In fact, history is littered with examples of European explorers imperfectly copying indigenous food processing techniques, and meeting gruesome ends.
Example 2: Pregnancy Taboos
Another example, again from Henrich:
During pregnancy and breastfeeding, women on Fiji adhere to a series of food taboos that selectively excise the most toxic marine species from their diet. These large marine species, which include moray eels, barracuda, sharks, rock cod, and several large species of grouper, contribute substantially to the diet in these communities; but all are known in the medical literature to be associated with ciguatera poisoning.
This set of taboos represents a cultural adaptation that selectively targets the most toxic species in women’s usual diets, just when mothers and their offspring are most susceptible.  To explore how this cultural adaptation emerged, we studied both how women acquire these taboos and what kind of causal understandings they possess. Fijian women use cues of age, knowledge, and prestige to figure out from whom to learn their taboos.  Such selectivity alone is capable of generating an adaptive repertoire over generations, without anyone understanding anything.
We also looked for a shared underlying mental model of why one would not eat these marine species during pregnancy or breastfeeding: a causal model or set of reasoned principles. Unlike the highly consistent answers on what not to eat and when, women’s responses to our why questions were all over the map. Many women simply said they did not know and clearly thought it was an odd question. Others said it was “custom.” Some did suggest that the consumption of some of the species might result in harmful effects to the fetus, but what precisely would happen to the fetus varied greatly: many women explained that babies would be born with rough skin if sharks were eaten and smelly joints if morrays were eaten.
These answers are blatant rationalizations: “since I’m being asked for a reason, let me try to think one up now”. The rationale for a taboo is not perceived by its adherents. This is yet another example of competence without comprehension.
A Theory of Overimitation
Human beings exhibit overimitation: a willingness to adopt complex practices even if many individual steps are inscrutable. Overimitation requires faith, defined here as a willingness to accept information in the absence of (or even contrasting with) your personal causal model.
We have replicated this phenomenon in the laboratory. First, present a puzzle box to a child, equipped with several switches, levers, and pulleys. Then have an adult teach the child how to open the box and get the treat inside. If the “solution” involves several useless procedures e.g., tapping the box with a stick three times, humans will imitate the entire procedure. In contrast, chimpanzees ignore the noise, and zoom in on the causally efficacious steps.
Why should chimpanzees outperform humans in this experiment? Chimpanzees don’t share our penchant for mimicry. Chimpanzees are not gullible by default. They must try to parse the relevant factors using the gray matter between their ears.
Humans fare poorly in such tests, because these opaque practices are in fact useless. But more often in our prehistory, inscrutable practices are nevertheless valuable. We are born to go with the flow.
In a species with cumulative culture, and only in such a species, faith in one’s cultural inheritance often yields greater survival and reproduction.
Is Culture Adaptive? Mostly.
We humans do not spend much time inspecting the content of our cultural inheritance. We blindly copy it. How then can cultural practices be adaptive?
For the same reason that natural selection produces increasingly sophisticated body plans. Communities with effective cultural practices outcompete their neighbors.
Overimitation serves to bind cultural practices together into holistic traditions. This makes another analogy to natural selection apt:
- Genes don’t die, genomes die. Natural selection transmits an error signal for an entire genetic package.
- Memes don’t die, traditions die. Cultural selection transmits an error signal for an entire cultural package.
Just as genomes can host individual parasitic elements (e.g., transposons), so too cultural traditions can contain maladaptive practices (e.g., dangerous bodily modifications). As long as the entire cultural tradition is adaptive, dangerous ideas can persist undetected in a particular culture.
Does Reason Matter? Yes.
So far, this post has been descriptive. It tries to explain why sapiens are prone to overimitation, and why faith is an adaptation.
Yet individual learning matters. Without it, culture would replicate but not improve. Reason is the fuel of innovation. We pay attention to intelligent, innovative people because of another cultural adaptation: prestige.
Perhaps the powers of the lone intellect are less stupendous than you were brought up to believe.
But we need not be slaves to neither our cultural nor our genetic inheritance. We can do better.
- Henrich (2016). The Secret Of Our Success.
- Henrich & Henrich (2010). The evolution of cultural adaptations: Fijian food taboos protect against dangerous marine toxins
- Henrich & Broesch (2011). On the nature of cultural transmission networks: evidence from Fijian villages for adaptive learning biases
- Dufour (1984). The time and energy expenditure of indigenous women horticulturalists in the northwest Amazon.
- Dufour (1994). Cassave in Amazonia: Lessons in utilization and safety from native peoples.