30 Dec 2022

Convergent adaptations

Posted by jofr

Daniel Goleman starts his book “emotional intelligence” [1] with the observation that many emotions are in fact adaptations to challenging situations where instant plans are required to act in order to protect the interests of the individual.

“All emotions are, in essence, impulses to act, the instant plans for handling life that evolution has instilled in us”
~ Daniel Goleman, Emotional Intelligence

Most emotions can be seen as adaptations to the adaptive challenges of the past. As Turner & Machalek say “any evolved features of the human brain/mind that contribute to the production of behavior, including social behavior, are the product of previous, archaic environments in which hominin ancestors lived. Accordingly, all such evolved adaptations represent solutions to ‘yesterday’s adaptive challenges.'” [7].

We have discussed earlier that bad feelings have an evolutionary purpose. There are “good reaons for bad feelings”, as the book from Randolph Nesse suggests [2]. For example the purpose of disgust is to tell us that we should avoid something because it might make us ill, the purpose of fear is to tell us that we should avoid something because it is dangerous, the purpose of pain is to tell us that we need to protect our body because it has been damaged and the purpose of depression is to tell us that we should stop doing what we do and try something different.

Disgust helps to get rid of potential poisonous food while suprise makes it easier to figure out what exactly is going on: “the lifting of the eyebrows in surprise allows the taking in of a larger visual sweep and also permits more light to strike the retina” [1]. Love facilitates cooperation and obviously increases reproductive success, while outrage helps to reveal defectors and anger prepares for vigorous action to prevent damage by offenses. Interestingly very similar adaptations can be found in cultural evolution, as Robert Boyd noticed [3].

Just like disgust in individual actors, food rules help to select the right food among the countless varieties of food. This helps to avoid food poisioning. Well known examples for such food rules are for example rules for kosher food or halal food that define what is allowed to eat and what is not. Pork is for instance neither kosher nor halal. Pigs ate everything including filth which could lead to parasitic infections. Therefore Pork was probably considered as unclean in ancient civilizations.

The prohibition of alcohol in the United States was led by pietistic Protestants and can be considered as a food rule in the Christian world. Alcoholic drinks are indeed toxic to a certain degree. Therefore the prohibition can be seen as a rule to avoid alcohol poisioning – which can indeed be deadly.

In general we can consider this kind of rules as a convergent adaptation to an environment which contains toxic substances. In biological and cultural evolution two different systems developed rules to avoid poisioning by bad and infected food. For outrage and pillory rules it is similar: both can be considered as an adaptation against defectors and defection. Two different systems which develop similar mechanisms.

biological emotion cultural rule purpose
disgust food rules to avoid posioning
love marriage rules reproductive success
outrage pillory rules, shame poles to reveal defectors
anger retaliation rules
like tit for tat
vigorous action to prevent damage

These examples of convergent adaptations are remarkable because they happen in different evolutionary systems: one in the system of biological evolution which is based on the genetic code, and one in the system of cultural evolution which is based on culture and language. We know of course convergent traits can be observed in the same evolutionary system. In biological evolution the streamlined bodies and fins of dolphins and sharks evolved separately, but they are both adaptations for swimming in their aquatic environment and are considered as convergent traits in the same evolutionary system.

Apparently similar adaptations can happen in different evolutionary systems too, not only in biological evolution, but also in cultural evolution. Boyd and Richerson define culture as “information that people acquire from others by teaching, imitation, and other forms of social learning” [4]. They see social learning as an adaptation of a cultural group to its environment where people acquire skills, beliefs and values which in turn affect behavior.

Robert Boyd argues in his book “A different kind of animal” [3] that cultural evolution helped in the accumulation of locally adaptive knowledge, and that we are successful as a species because we have access to a huge amount of culturally transmitted knowledge including many adaptive rules that helped us to survive. He gives the concrete example of a Fiji island where pregnant women are traditionally not allowed to eat large predatory fish which have indeed often higher levels of toxic substances that can cause poisoning. Boyd writes “the evolution of cultural adaptation was an essential ingredient in both our ecologigcal success and our ability to cooperate” [3].

As a result of cultural adaptation the group follows a shared set of common rules how to act which is passed on to the next generation by social learning. More important than food rules that determine what to eat are rules about how to cooperate, or as Charles Stanish says, how to “co-operate” [5] in “coordinated operations”. These cooperation rules help to reduce conflicts inside the group, and they are the foundation of religious groups too. The ability to cooperate over generations is the secret of our success, as Joseph Henrich says [6].

Even if a group is well adapted to its environment, has a cohesive form and passes its rules orally to the next generation, it is not necessarily permanent. Stateless societies made of tribes and family clans are like lakes of water made of droplets. They can combine to larger groups, change their form and shape, and they can dissolve again. Only if they obtain a shell of written rules they become more durable, like a drop of water which becomes a hard sphere. Durability requires a written code or codex which need to be taught frequently. Once stateless societies have developed a writing system and start to practice high-frequency rituals which can help to standardize a body of beliefs and practices in a larger population, they can pass the threshold to higher forms of complexity. Harvey Whitehouse calls this “doctrinal” mode [8]. If the high-frequency rituals involve the teaching of moral rules, a new kind of entity can emerge: a religious entity which can be seen as a life-form. These archaic life-forms are a first step towards states and institutions.


[1] Daniel Goleman, Emotional Intelligence: Why It Can Matter More Than IQ, Bantam Books, 1995
[2] Randolph M. Nesse, Good Reasons for Bad Feelings – Insights from the Frontier of Evolutionary Psychiatry, Penguin, 2020
[3] Robert Boyd, A Different Kind of Animal: How Culture Transformed Our Species, Princeton University Press, 2017
[4] Robert Boyd and Peter Richerson, The Origin and Evolution of Cultures, Oxford University Press, 2005
[5] Charles Stanish, The Evolution of Human Co-operation. Ritual and Social Complexity in Stateless Societies, Cambridge Universitry Press, 2017
[6] Joeseph Henrich, The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter, Princeton University Press, 2016
[7] Jonathan Turner and Richard Machalek, The New Evolutionary Sociology: Recent and Revitalized Theoretical Approaches, Routledge, 2018
[8] Harvey Whitehouse, The Ritual Animal: Imitation and Cohesion in the Evolution of Social Complexity, Oxford University Press, 2021


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