The evolutionary origins of the HEXACO personality factors

The HEXACO model is an improvement over the Big Five inventory. However, merely adding new personality dimensions is of little use when it comes to understanding human nature, as not even five factors are human universals (at least, from our current understanding). Two of the factors that are often associated with mental disorders (neuroticism and openness to experience), never even show up in non-Western societies. Accordingly, these traditional societies have many fewer mental health problems than us people in Western societies,  which are called “WEIRD” (Western, educated, industrialized, rich and democratic) by Joseph Henrich in The WEIRDest People in the World (2020). Henrich points out the Big 5 are indeed WEIRD 5, as they are by no means human universals. Some societies yield only three or four factors. Subsistence-level economies often only have two factors. The Tsimane'  practise subsistence farming and Henrich writes about them:

So, did the Tsimane' reveal the WEIRD-5? No, not even close. The Tsimane' data reveal only two dimensions of personality. No matter how you slice and dice the data, there’s just nothing like the WEIRD-5. Moreover, based on the clusters of characteristics associated with each of the Tsimane'’s two personality dimensions, neither matches up nicely with any of the WEIRD-5 dimensions [...] these dimensions capture the two primary routes to social success among the Tsimane', which can be described roughly as “interpersonal prosociality” and “industriousness.” The idea is that if you are Tsimane', you can either focus on working harder on the aforementioned productive activities and skills like hunting and weaving, or you can devote your time and mental efforts to building a richer network of social relationships.

The two personality profiles that emerge from these farmers are a more provisioning (male majority) and a more caregiving one (female majority) from an evolutionary point of view. The same can be expected from other subsistence economies: for foragers you will get a “hunter” profile and a “gatherer” profile. What these two factors thus capture is the ancient evolutionary difference between male and female traits. In the Big 5 this trait is represented by the factor “agreeableness” and thinking vs feeling (T/F) (testosterone/estrogen) in Jung/Myers-Briggs (MBTI). Men are on average much lower in agreeableness than women. Women often complain about men and their lack of empathy, however, it is their very female ancestors who sexually selected the traits men have.  So, the term “agreeableness” for this personality dimension is somewhat unfairly biased against men.

According to our ancestral mode of subsistence, we can derive six (3x2) different personality profiles (with MBTI) for foraging, farming and herding:

These six types occupied different evolutionary environments and roles and would therefore have had different kinds of adaptations. Evolutionary psychologists have for the most part assumed that we can treat all people as neolithic “hunter-gatherers” when it comes to our evolved psychology. However, it should be clear that these three subsistence strategies are very different and require different psychological and even physiological adaptations.

Assuming that ancient farmers had much harder and shorter lives than foragers, they would also have a tendency to have a higher reproductive rate (one child every 2-3 years) than hunter-gatherers (one child every 3-4 years).  When it comes to mate choice a farmer-female would choose a male who achieves high food productivity and by doing so selected all the traits that were required: industriousness, conscientiousness, delayed gratification, long-term planning capabilities. Yes, these traits sound very much like the Big 5 trait “conscientiousness” with all of its facets. These traits most likely did not exist in humans before the advent of agriculture and sedentism. Conscientiousness also goes hand in hand with many other traits that were necessary for early farmers: conformism, love of tradition, love of strict rules (law and order).

Pastoralists had most likely the hardest and shortest lives of all. According to life-history (LH) strategy, they should be risk-takers and somewhat sociosexual. Indeed, it is pastoralist tribes that had historically the highest rates of polygamy and who tended to wreak havoc among their farmer neighbours: the Yamnaya (Indoeuropeans), Huns, Mongols, Vikings, were all pastoralist tribes feared by their farmer neighbours.

We, thus, arrive at the following LH traits:

Each of these personality profiles would have had evolutionarily selected optima (fine-tuning) when it comes to traits such as extraversion (which includes risk-taking), which probably left much less room for variation than in modern societies, which are basically a mix of all three personality types. However, due to evolved mate preferences, we can expect that these traits are not completely mixed in the gene pool. Assortative mating is a well-known phenomenon in psychology, and I am certain it works along the lines of these ancestral personality types. The anthropologist Helen Fisher has found four personality profiles that tend to date and mate. They align well with my proposed evolutionary temperments.

As MBTI is usually considered pseudoscience I will translate this model into the HEXACO model, which is derived from statistical methods that are considered more scientific than MBTI. This model was developed by Keebom Lee and Michael Ashton. In The H Factor of Personality: Why Some People Are Manipulative, Self-Entitled, Materialistic, and Exploitive and Why It Matters for Everyone (2012) they make an interesting theoretical distinction between three types of action orientation  

C: hard routine work, practical, conscientiousness avoids pathogen, delayed gratification

X: forming alliances, risk-taking, higher sociosexuality, spontaneity

O: tendency to engage in idea-related endeavours

 

and three types of altruistic orientation with potential selective mechanisms producing them:

 

E: kin altruism

A: the “patient” kind of reciprocal altruism (i.e. you expect future return)

H: the “fair” kind of reciprocal altruism (i.e. you are altruistic even when there is no likelihood of direct reciprocity)

We can now tentatively map these traits onto the six evolutionary profiles, seeing each trait as maximum adaptive value for the receptive profile:

The highest value of agreeableness goes to the caregiving farmer profile. Farmers evolved hierarchical societies with high population densities, high agreeableness reduces conflict and tensions and maintains the hierarchical order. High agreeableness should therefore also be somewhat sensitive to status.

Each personality factor comes with a bundle of traits. In order to find out if my assessment is somewhat realistic we have to check if the sub-facets of each factor match with the respective evolutionary environment I have proposed:

Conscientiousness includes the facets or sub-traits of being achievement-oriented, cautious, dutiful, orderly, self-disciplined, and prone to self-efficacy. I have argued that high conscientiousness only evolved late in human evolution, i.e. with the advent of horticulture/agriculture. Basically, all the facets are indications:

Achievement orientation (industriousness): farmers had to work more and harder for subsistence than hunter-gatherers. Cautious and detail-oriented work habits: farming required long routine work with a constant focus on many details (sowing, weeding, harvesting, etc.). Orderliness is all about changing the environment for your needs rather than adapting to an environment. Self-discipline and delayed gratification had never been this important in hunter-gatherer life, who immediately consume whatever they have to eat. For early farmers eating the seeds rather than showing them would have been detrimental. Walter Mischel’s famous Marshmallow experiment has shown how much even little children differ in their ability for delayed gratification. There really isn’t that much difference between marshmallows and grains from an evolutionary point of view. Dutifulness: a lot of farming effort, especially irrigation farming, had to be organised hierarchically rather than in an egalitarian hunter-gatherer way. Again, it was of vital importance that farmers fulfilled their position in a hierarchy and followed orders without too much protest. Finally, high conscientiousness and high disgust go together. This trait helped sedentary farmers fight higher numbers of pathogens.

Openness involves six facets, or dimensions: active imagination (fantasy), aesthetic sensitivity, attentiveness to inner feelings, preference for variety (adventurousness), intellectual curiosity, and challenging authority (psychological liberalism).

By now it should be clear that a lot of farmer traits are incompatible with the nomadic lifestyle of egalitarian hunter-gatherers. Openness predicts and preference for variety, which is exactly what we would expect for nomadic people (hunter-gatherers or pastoralists). Sensitivity: hunter-gatherers are highly in tune with their environment and experience themselves as a part of nature rather than the humans vs nature experience of farmers. Imagination is highly important for hunters when tracking animals as they have to imagine several possibilities simultaneously. Not only do hunters infer what kind of animal they are tracking, but also details, like its age, speed, direction, state of exhaustion, etc. Hunter-gatherers living in our “farmer” world would also frequently challenge authority as they are highly egalitarian and would accept only temporary leaders based on high competence. Moreover, being a hunter-gatherer means being a life-long learner. Foragers have an encyclopaedic knowledge of the surrounding flora and fauna and it is typically the older rather than the younger, fitter members of the band who are the most successful hunters.

Each personality factor is therefore associated with an evolutionary environment. High C was a highly successful strategy for farmers, high O for hunters, albeit not in the form we know today (interest in philosophy, science, aesthetics). People with high O explore museums and scientific concepts nowadays rather than animal tracks, plant species and new foraging terrains. People high in C are successful business managers, on the other hand. Of course, there can be combinations and a lucky few are high in both O and C and often highly successful in our "farmer world". However, studies have shown that high O and C tends to be very low in reproductive success, the only kind of success that really counts in evolution.

The facets of eXtraversion are: activity, assertiveness (dominance), excitement-seeking (risk-taking), novelty-seeking, gregariousness. All these traits match with the subsistence environment of pastoralists. High activity levels go with herding, risk-taking with pastoralist raiding, novelty-seeking with nomadism and gregariousness with pastoralist social organisation (segmentary lineages) and the constant forming of alliances.

The above evolutionary model of temperament based on subsistence and HEXACO are therefore compatible:

What is more, these personality profiles are also perfectly compatible with Shalom H. Schwartz’s circle of (partially opposing) values:

Security, conformity and tradition make sense for early farmers, who in contrast to foragers or pastoralists couldn’t just relocate when there were external threats like natural disasters or raiders. Conformity goes hand in hand with agreeableness and tradition has a lot to do with the skills required for farming and maintaining the status quo (stability).

Personality factors provide a map of our evolutionary origin. Check out my book for more background information on mapping human nature:

https://www.amazon.com/dp/B09LSF98WV