A general theory of personality based on social selection and life-history theory

When it comes to personality psychology the Big 5 (or Five-Factor Model/FFM) are still considered the gold standard and many other personality tests, like the Myers-Briggs (MBTI) are considered pseudoscience. The FFM is even more useful and has more predictive power when a sixth dimension is added: honesty humility (HEXACO model).

However, adding new personality dimensions is little use when it comes to understanding human nature, as not even five factors are human universals. Two of the factors that are often associated with mental disorders (neuroticism and openness to experience), never even show up in non-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.

Henrich doesn’t mention it, but the two personality profiles that emerge from these farmers are 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 T/F (testosterone/estrogen) in 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 therefore derive six (3x2) different personality profiles:

Going even further back in time when there was no division of labour we find the general factor (GF) of personality: “socially and sexually desirable traits”, or being socially appreciated, which made sure the individual would be socially accepted and a desirable mate. The GF was therefore socially and sexually selected traits. The increasing division of labour happened due to mate preferences: a skilled provider (also technical problem solver) for females and a skilled social problem solver (also caregiving profile) for males. Depending on the different subsistence level economies different personality traits become desirable: competence (hunting is a skill that takes life-long learning) for foragers, productivity and industriousness for farmers (farmers had to work many more hours.

Assuming that ancient farmers had much harder lives than foragers, they would also have a tendency to have a higher reproductive rate than (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”. These traits most likely did not exist in humans before the advent of agriculture. 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 strategy, they should be the risk-takers and somewhat sociosexual. Indeed, it is pastoralist tribes that tended to wreak havoc among their farmer neighbours in history: the Yamnaya (Indoeuropeans), Huns, Mongols, Vikings, etc. We, thus, arrive at the following 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 the four MBTI temperaments and my proposed evolutionary types:

Fisher also states that these types look for different traits in their mates. Builders (farmer types) want a helpmate, explorer (pastoralist types) want a playmate and directors/negotiators want soulmates. This characterisation fits well with there different evolutionary types.

This model would account for the assortative mating among people with ASD and other forms of neurodiversity. These people are most frequently hunter types, who prefer (female) hunter or gatherer types as mates. Autism frequently runs on both sides in the family and autism rates can be extremely high in places that attract hunter-types, such as university centres (MIT has high autism rates among their staff’s children) and Silicon Valley. It is a well, known fact, that autistic children have on average much older fathers. This can partially be explained by life-history traits (later puberty), but also due to higher social awkwardness. Hunter and gatherer ironically often find each other because they are the “leftovers” who are still unpartnered when herder and farmer types have long found their partners.

In connection with autism, it is also interesting to note that the provisioning/prosocial split (i.e. evolution of gender roles) may have been responsible for what is known as the “great leap forward”, or human inventiveness. Basically, almost all inventors are of the hunter-type (Edison, Mark Zuckerberg, Elon Musk, etc.). This evolution may have happened over thousands of years, culminating in what is known as the Upper Paleolithic Revolution about 40.000 years ago. This is might mark the split between the General Factor of Personality and the provisioning/prosocial personality profiles, whereas the further split into forager/farmer/herder types is marked by the Neolithic Revolution.

Originally published at http://the-big-ger-picture.blogspot.com on January 4, 2021.