Thought of the day: could there be an equilibrium of personality types?

Suppose you buy the idea popular in psychology that there are stable personality types largely formed in childhood and that the population has relatively stable proportions of these personality types. The Big5 personality types are agreeableness, extraversion, neuroticism, conscientiousness and openness. Often added to this list is Locus of Control. Other traits like analytical ability, empathy, and shyness are also often mentioned in the many lists of personality doing the rounds.

There is some indication that personality is heritable and partially genetic. Genes for shyness have been claimed, as for neuroticism and risk-taking (although there are of course lots of caveats and uncertainties about any claim). The prevalence of those genes differ by region.

If you buy this idea, then the question arises how the distribution of personality types came to be and what sustains it or changes it? What could the forces be that lead to an equilibrium of personality types?

  1. Perhaps some types are more likely to get killed in certain wars and others are more likely to survive, for instance shy and anxious people. Wars would then lead to increases in the proportions of the personalities that favour survival, whilst in inter-war periods other pressures might prevail that select against shyness.
  2. Social selection for breeding. Perhaps some types have more children or make more popular breeding partners.
  3. Social pressures and opportunities that favour proportions of types. One can here think of group types wherein there are ‘slots’ for different personality types in fairly constant proportions. Leaders, followers, creative thinkers, jokers, motivators, etc.

Options 1 and 2 would lead you to believe personality distributions change only slowly outside of catastrophic occasions, and are mainly genetically transmitted. Option 3 fits a more fluid view in which personality is not fixed at birth but more a kind of deep strategy picked up early on but particular to the environment. The possibility that personalities that are at the moment associated with low levels of happiness might be useful in various future eventualities is of course consoling in that some sources of misery might be functional in the long-run. It also raises the possibility that a national personality distribution tells us something about that countries’ history.

Just a thought.

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19 Responses to Thought of the day: could there be an equilibrium of personality types?

  1. Paul
    Only two of my personalities are schizophrenic,
    however one of them is paranoid and the other is always out to get him.
    It’s only when I have no idea what I’m doing that I paint well.

    Curious, what are you thinking about?

    • paul frijters says:

      oh indeed, we’re all certifiably nuts. Some of us have merely been lucky enough to avoid early certification.

      I am so far just playing with this stuff, John. It’s clear there is, in a rough sense, such a thing as a personality equilibrium which changes only slowly. And chemical, genetic, economic, and cultural circumstances all play some role. What we lack are good stories as to how it roughly works and can be manipulated.

      I have lots of preliminary questions I would want to ask someone who is true expert in cross-cultural personality research. For instance: do migrants retain the personality they had before migrating? Do migrants start to accentuate parts of their personality that were dormant before migration? How about migrants from different countries were supposedly the distribution is very different? Is it true that food, immunity, diseases, and upbringing play a large role in some personality-related mental dispositions (like autism, which seems to be on the rise)? And how? Is there is a distinct personality pattern discernible inside organisations? Does the distribution move towards whatever is more economically successful in a region? Is there assortative mating on personality? Is there any clear pattern between cultures and personality distributions? Etc.

      • Paul given that the brain is much more plastic than was previously thought, it would be surprising if at least some of the things you are mulling over don’t happen all the time.

        Yeats Ego Dominus Tuus
        Takes the form of a dialogue between self and anti-self.
        It begins:

        ON the grey sand beside the shallow stream
        Under your old wind-beaten tower, where still
        A lamp burns on beside the open book
        That Michael Robartes left, you walk in the moon
        And though you have passed the best of life still trace
        Enthralled by the unconquerable delusion
        Magical shapes.

        By the help of an image
        I call to my own opposite, summon all
        That I have handled least, least looked upon.

        Hic. And I would find myself and not an image.

        Ille. That is our modern hope and by its light
        We have lit upon the gentle, sensitive mind
        And lost the old nonchalance of the hand;
        Whether we have chosen chisel, pen or brush

        We are but critics, or but half create,
        Timid, entangled, empty and abashed
        Lacking the countenance of our friends.”

        The poem concludes with concludes:

        Why should you leave the lamp
        Burning alone beside an open book
        And trace these characters upon the sands;
        A style is found by sedentary toil
        And by the imitation of great masters.

        Because I seek an image, not a book.
        Those men that in their writings are most wise
        Own nothing but their blind, stupefied hearts.
        I call to the mysterious one who yet
        Shall walk the wet sands by the edge of the stream
        And look most like me, being indeed my double,
        And prove of all imaginable things
        The most unlike, being my anti-self,
        And standing by these characters disclose
        All that I seek; and whisper it as though
        He were afraid the birds, who cry aloud
        Their momentary cries before it is dawn,
        Would carry it away to blasphemous men. “

  2. conrad says:

    I think you really need to make clearer the difference between something being heritable and what we actually know about the genetics of particular genes for complex behaviors. For example, it’s more or less undoubtable that things like anxiety (and hence some personality correlates) are reasonably heritable — but of course what doesn’t have some heritable component? Alternatively, when trying to identify genes for broad behavioral indicators, the amount of variance that can be explained is tiny (~2% at best in most studies I’m aware of), and even then you don’t know what the genes do, and for that matter, what a gene does may have no obvious explanation at the level people like to think at (i.e., a macroscopic level using psychology concepts). For example, for all I know, people booze more in cold climates and some groups clearly have better genes for digesting booze, and therefore they have less anxiety in cold countries because they’re drunk all the time and don’t worry about things. Of course, these genes to do with digestion of booze won’t have one effect — they’ll have many, and all could affect something like anxiety given anxiety can be caused by lots of things.

    Given this, it seems to me your suggestions are mainly based on things which are conceptually easy to identify at the macroscopic level, and this is level genes don’t care about that much (like trying to explain the coast via reference to grains of sand). An alternative is that there is just random drift all over the place, and hence any differences you find across populations, even when you can identify the likely source, may have no explanation at the level you are thinking (and indeed, you won’t even be thinking about the 10 other non-obvious changes caused by your genes that don’t seem related to your question at all). Examples of things where people once incorrectly thought the explanation would be simple are:”Why do Southern Chinese people have bad eyesight?”,”Why do Australians have high levels of Asthma”, “Why do people in Switzerland have lots of allergies?”. Everyone would like a simple causal explanation for these, but for all I know, it’s just random drift — and these are all factors with obvious physiological correlates and so the explanation should be comparatively easy compared to non-obvious psychological phenomena.

    Another thing to think about is the speed of evolution. If you look at things with direct pressure to survival, people look for ranges of about 1000 years to find differences (For a fun example that came out a few days ago, look here). How fast is this going to happen to with complex cognitive traits that don’t have life-or-death pressure? If I remember Stephen J. Gould and what he said in his famous book the Mismeasure of Man, even 30,000 years wasn’t enough. Given this, even if he is out by a factor of 10, you’re still looking at timespans vastly longer than anything that stays or has stayed stable with most human populations.

    Finally, rather than look for just-so stories at the macro level, why not look for negative instances. For example, cold places look depressing to me. Therefore, I would assume that people with ancestors from cold places should have built up lots of protective genes against depression. Thus, if I look at people who recently migrated to hot places, like for example, white Australians, they should hence not suffer depression, because they will have protective genes and won’t even have to put up with depressing environments. As is obvious, that isn’t true. But everyone believes a difference if it seems right, but no-one thinks about differences that don’t exist with equally as strong evidence.

  3. derrida derider says:

    Well, if you accept that there are fixed personality types with clusters along a limited number of dimensions, and if you accept that their proportions are largely invariant to culture/upbringing (both of which need empiric proof) then the normal game theory mechanisms of modern population genetics would be applied – we observe these (contemporarily) invariant proportions of fixed types because there exists (or at least existed) an Evolutionary Stable Strategy (ESS) that favoured coexistence of the types, possibly cyclically varying over the evolutionary past.

    It is, as usual, easy to then create “just so” stories that set this game up. Creating a **testable** story is, again as usual, another matter.

    • DD
      There might be a indirect way of testing the story via, stories?

      The current NYRB in a piece on Hamlet states :

      It’s a truism that no one accepts anyone else’s reading of Hamlet. And for at least two hundred years, no generation has been comfortable with its predecessor’s take on the play. It’s hard to think of another work whose interpretations so uncannily identify what the play calls the “form and pressure” of “the time.”

      Article then goes on to outline how over the past 250 years, interpretations of Hamlet’s ‘personality’ have changed in ways that reflected ,or at times anticipated, wider generational cultural shifts.

      Perhaps surveys of literature ,popular culture etc, both across time and across nations could identify whether changes in the frequency of types and kinds of personalities are random drift or not?

  4. Two previous attempts I can recall:

    Penke et al.

    David Buss

    • paul frijters says:

      thanks Jason, very useful. The Penke et al. study has a lot of interesting literature in it that indeed engages in some story-telling. I particularly liked the discussion about the Italian island that has few extroverts and the following passage on risk-taking genes (7R):

      “More direct evidence for the importance of environmental heterogeneity in the evolutionary genetics of human personality comes from studies of the global distribution of polymorphisms at the DRD4 locus. This gene regulates dopamine receptors in the brain and has been associated with personality traits such as novelty seeking and extraversion (Ebstein, 2006). The prevalences of different DRD4 alleles differ dramatically across world regions. The evolutionarily newer 7R allele, which is more common in risk-prone,
      response-ready, extraverted novelty seekers, is much more prevalent in European and American populations than in Asian populations (Chang, Kidd, Livak, Pakstis, & Kidd,1996). This allele appears to be favoured by selection (1) when benefits can be gained from migrating to new environments (Chen, Burton, Greenberger, & Dmitrieva, 1999; Ding et al., 2002), and (2) under resource-rich environmental conditions (Wang et al., 2004).

      Referring to these findings, Harpending and Cochran (2002) noted that under conditions of environmental harshness and resource scarcity (as is common in hunter-gatherer societies), intensive cooperation, strong family ties, stable pair bonds, and biparental investment are necessary for survival and successful reproduction. These ancestrally typical conditions would maintain the more risk-averse, ancestral form of the DRD4 gene. But under more
      luxuriant environmental conditions, when children can survive without so much paternal support (as in most agricultural and modern societies), the more risk-seeking 7R allele should be favoured by selection, as it leads to a personality more prone to sexual promiscuity and intrasexual competition (Gangestad & Simpson, 2000; Schmitt, 2005).”

      7R sounds like a good allele to have!

      • conrad says:

        I’m glad we know how dopamine works now. Of course, presumably one should also predict overall differences in schizophrenia, addiction, and a million other things less complex than personality given dopamine’s status in the brain, if these differences are really so important.

        Incidentally, if you just want mediated effects on personality, the alcohol genes are obvious ones here . Clearly people with these genes won’t show as much aggression, will have less alcohol addiction etc. ., and when you go to these parts of the world you will be able just confirm that yourself by eyeballing what happens at night (i.e., there is a decent cultural effect of most people not drinking). Perhaps they will have to develop genes for more extraversion as they won’t be able to use alcohol to help facilitate partner selection :).

        If you want to add intelligence to personality (via less creativity), then that’s an obvious one with a huge and widespread selection effect, and we’ve clearly created the social conditions for it. People even estimate the overall drop over time. But it’s not really one social circumstance — less intelligent people have less children in any number of countries now.

        • paul frijters says:

          Hi Conrad,

          I can imagine your frustration at such easy stories whilst there is a huge complexity and so much that we dont know. And indeed, it may all just be natural drift. Yet, I do think that story telling is how we progress: from simple stories to more complex ones, being wrong at every step but at least on the move and thus with some hope of hitting the right direction.

          So the question is less why you don’t like the stories Jason links to. The question is which alternative stories you have to offer? What is your best guess?

  5. conrad says:

    Basically I agree with Stephen J. Gould that evolution just doesn’t work that fast — which basically means there will be no meaningful direct effects of evolution for the type of things you are thinking of. As noted, if you look at absolutely serious life-or-death pressure, then even in 1000 years the number of changes you get is pretty small, but they are useful (and only then for a small number of these types of pressures). Of course, number is a difficult concept with genes, because small changes in physical attributes can lead to relatively large outcomes (e.g., going from mouths to beaks is caused by a surprisingly small number of genes — but took huge amounts of time, despite being useful). However, things like personality are just not that simple, and are no doubt controlled by large numbers of genes, all of which do any number of things and interact in ways we can’t even contemplate understanding at present (the same holds for the neuroscience — the best we do is look at correlations). This means you have a mere 50 generations (for 1000 years of stable social pressure) to get some meaningful change for something which in the best case is extremely messy and affected by relatively weak factors (swimming in a larger number of other changing factors). Thus, the only way you are going to get changes are if you can get something that affects more or less all the population and populations in different places (like SES, IQ, and number of children born).

    To some extent, I also agree with some aspects of probably the left’s most hated IQ researcher, Charles Murray. Basically, there are differences between any groups if you look hard enough (often not meaningful). Given recent research has shown that moderns humans are really more variable than what we used think (thanks Neanderthal etc.; although still not very variable compared to other species) and there is just going to be genetic drift in different populations, there really will be differences that might correlate with complex behavior. So the fact you can find differences on some measures across populations is no big deal, but the possibility they have come from social pressure like “society likes jokers” seems to be about zero.

    So I think the simple story really is gone, and it’s been gone for ages, but people always like simple explanations for hard problems (especially the popular science crew). If evolution of complex things really works in 50 generations, we will clearly need a new theory (and we’ll have to wonder why even useful changes, like the evolution of different bird beak shapes for different environments, takes so comparatively long).

    What can be done about this to learn more? Well, at present we need new ways of examining genes. At least in my books, most of the mass correlational methods have failed — there are many things we know have a large genetic contribution (e.g., body mass and height), that they pick up tiny amounts of variance on. This includes all of the things like educational achievement and similar that I’m aware of (i.e., the stuff from 23 and me and similar groups). So using a taxonomy of behavior associated with particular genes found via simple association doesn’t work (In hindsight, I was personally fortunate not to have wasted my time looking for them in my area — many years ago I once thought it was a great idea and something I should do ). So basically, in terms of progress, I’m waiting for a breakthrough in methodology and ways of applying it to complex problems.

    • paul frijters says:

      thanks Conrad. I agree that the burden of proof is on those spinning any story about personality selection.

    • Conrad
      Wasn’t there a long running Russian experiment that showed that you could, over about 20 generations , if you applied a lot of selection pressure, create a relatively domesticated fox?

      • conrad says:

        John, yes I know about that (there are other examples). You can definitely breed animals pretty quickly if you have really ruthless selection (as in essentially 100% chosen each time from small samples). One of the interesting things about it apart from the fact that you can do it, is that they got other changes too (colour etc.). It would also be interesting to know the extent to which they have restricted the gene pool on other things (i.e., whether they have created an end-of-the-line type animal like some of the other pure-breed dogs that have all the health problems). Given aggression is very useful in survival, it is an interesting find, and would be interesting to examine in other animals where aggression is not so useful and which you cannot domesticate (which is most animals) to see how much longer it would take.

    • Nicholas Gruen says:

      I’m not sure I’m following you here Conrad. Perhaps I’ve got the wrong end of the stick. Are you aware of Geoffrey Clark’s work in which he argues – with some quite persuasive evidence that a major contributor to the industrial revolution was the extent to which the relative domestic peace of the mediaeval period in Britain had favoured traits like patience and similar traits that help to promote for saving and investing over their opposite which leads to marauding and violence?

      This seems to me to show the social realm feeding back through to the genetic base. (Acknowledging that the traits are only partially determined genetically.)

      Also, to what extent are you keeping in mind the possibility of the kinds of mechanisms that Denis Noble appeals to in Dance to the Tune of Life as means of accelerating progress. His suggestion is that methods of ‘targeted randomisation’ if I can use that expression (there’s presumably a specific bit of jargon I don’t know) analogous to the way in which our immune system works could be deployed to ‘solve’ problems that arise in nature – helping the giraffe to evolve the various systems necessary (eg higher blood pressure) as her neck lengthens through the eons.

      • I’d guess that the evolution of education systems-texts etc (particularly re the first seven or so years of life ) would be a better area to look for drivers of directional changes in national personality profiles .
        If you view humans ,as if, they were computer-operating systems , so much of the information and sets of instructions that we use is external to us as individuals.

  6. conrad says:

    I’m aware of Geoff Clark’s stuff — I’m happy to have social change leading to economic change, although I’m sure you’re far better at evaluating those arguments than me!

    In terms of genetic changes in 600 or so years that could lead to the type of cognitive differences he suggests (a mere 30 generations with a constant influx from outsiders diluting any changes) — it’s up to him to provide vastly better evidence based on well established theories in biology and the endless counter examples that are not predicted by his suggestions (some of which he already notes)

    People in my area argue about language capacity and whether early humans were similar to now or not. We can’t come any great conclusion, but at least people allow for change over tens of thousands of years!

    I haven’t read Denis Dance to the Tune of Life, but it looks interesting (perhaps one day I’ll get time!).

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