While our personality traits such as honesty are much more dependent on the environment and circumstances, it has become clear that our temperaments have a solid biological foundation. Unfortunately, genetics has turned out to be much messier than hoped for, but it has become clear that genes are involved in neurotransmitters, such as dopamine (DAT) and serotonin transporter genes (5-HTTLPR).
I have found several approaches to temperament and neurotransmitters/hormones. One of the first approaches I found was Helen Fisher, whose classification combined with mine looks like this:
While testosterone (male) and estrogen (female) hormones are problematic (plus, they are hormones and not neurotransmitters), they do nicely correspond to the NT/NF distinction in the Myers-Briggs/Keirsey inventory. Looking for another classification based on I came across Erich Braverman, whose four temperaments are very close to Keirsey’s. However, the mapping of neurotransmitters to temperament is very different and confusing.
Assigning dopamine to risk-taking and novelty-seeking pastoralist (SP) types and serotonin to stability-seeking farmer (SJ) types, just like Fisher has done, makes much more intuitive sense. One of my early leads in my research was oxytocin, the hormone of love and laughter that is also a neurotransmitter.
By chance, I came across a book that had everything I had hoped to find. Can the ancient four temperaments be explained by modern neuroscience?: The neurobiological foundation of the popular personality types (2020) Mary Zasser combines Keirsey and modern neuropsychology and comes up with neurotransmitter profiles that are a little reminiscent of function stacks (primary function very high, secondary, medium-high, etc.):
Profile for SJ/farmer types
These functions correspond well to evolutionary adaptations of early farmers: long focus on route work, attentiveness to external threats and social conformity, high loyalty (long-term alliances required for long-term cooperation) and delayed gratification (impulse control). I have written in more detail about the evolutionary psychology of early farming. In a nutshell, it required all the traits contained in the Big 5 factor “conscientiousness” (avoiding pathogens, duty-conscious, etc.), a close-knit, long-term community easily recognizable by uniform characteristics (e.g. accent, clothes, etc.) and hierarchical organisation (in the case of irrigation farming) and compliance.
Zasser’s profile for rationals (hunters) looks like this:
Profile for NT/hunter types
Hunters are high in acetylcholine or hyperfocus. This is a trait required in persistence hunting, in which hunters follow the tracks of an animal, constantly updating hypotheses such as direction, speed, age and of course type of animal. This kind of hyperfocus is often seen in children with ADHD and ASD (neurodiverse). Even if hunters are great at hyper-focusing on tasks that they find relevant or interesting they do a poor job on routine tasks as hunter-gatherers only work intermittently and not long hours like farmers. This is exactly what we see in neurodiverse children, who struggle with paying attention in school but have no problem playing computer games or keeping themselves busy with their special interests for hours.
Hunters don’t need a lot of social empathy and cognition as hunter-gatherers are egalitarian and have no concept of politeness, etiquette, and social status. All these concepts make much more sense for food producers, in particular for farmers. It’s also what we see with neurodiverse children, who struggle with authority, politeness and social conformity in general. Also, note that hunters are low in gratification by achievement. Hunter-gatherers aren’t competitive (not even their games are) and are very low on external motivation like status and money.
While it is unlikely that we will ever find one to one correspondence between neurotransmitters and our traits, the simplified picture we now get is this one:
For more on the hunter-gatherer neurotribe idea check out my book
https://www.amazon.com/-/de/dp/B0836LW5QV/
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