family types and the selection for nepotistic altruism

it finally clicked in my head while thinking about polygamy what the importance of family types — nuclear vs. extended, etc. — might be in the selection for altruistic behavioral traits, especially nepotistic altruism or clannishness. i should’ve thought through polygamy sooner instead of putting it off, but hey — procrastination is heritable, too, so in the words of h. solo, it’s not my fault! (~_^)

the logic of the mating patterns/inbreeding-outbreeding theory goes that, given the right set of circumstances (i.e. certain sorts of social environments), selection for nepotistic altruism/clannishness ought to go quicker or be amplified by inbreeding (close cousin marriage or uncle-niece marriage) simply because there will be more copies of any nepotistic altruism genes (alleles) that happen to arise floating around in kin groups. in other words, inbreeding should facilitate the selection for clannishness…if clannish behaviors are being selected for in a population.

the thing is, though: the individuals carrying certain versions (alleles) of nepotistic altruism genes need to direct their nepotistic behaviors towards other individuals carrying those same alleles, otherwise their actions will be for naught. (yeah. kin selection.) if they direct their nepotistic actions towards people who don’t share the same alleles, then the actions will be “wasted” and the behavioral traits won’t be selected for — or at least not very strongly — and they might fizzle out altogether.

let’s take an imaginary society as an example: say everyone in our pretend population always marries their first cousins. their father’s brother’s daughters (fbd) even, so that we get a lot of double-first cousin marriage. h*ck! let’s throw in some uncle-niece marriages on top of it all. the inbreeding coefficients in such a society would be very high, and if clannishness was being selected for in our highly inbred population, the selection ought to move pretty quickly.

but suppose we separated all the kids at birth from their biological families and set them out for adoption by unrelated individuals — people with whom they likely did not share the same nepotistic altruism alleles. think: the janissary system, only on a population-wide scale. if we did that, there should be virtually no selection for clannishness despite all the inbreeding since pretty much no one’s nepotistic behaviors would be directed towards other individuals with the same nepotistic altruism genes. in this case, kin selection would just not be happening.

such a society does not exist, and i don’t think ever has. but there are societies out there with certain family types — namely nuclear families (or even post-nuclear family societies!) — which ought to have a similar dampening effect on any selection for clannishness.

northwestern “core” europe has had very low cousin marriage rates since around the 800s-1000s, but it has also, thanks to manorialism, had nuclear families of one form or another (absolute or stem) since the early medieval period — nuclear families are recorded in some of the earliest manor property records in the first part of the ninth century from northeastern france [see mitterauer, pg. 59]. on the other hand, eastern europeans, like the russians and greeks, while they also seem to have avoided very close cousin marriage for several hundreds of years (which is not as long as northwestern europeans, but is quite a while), have tended to live in extended family groupings. you would think that nepotistic altruism could be selected for, or maintained more readily, in populations where extended family members lived together and interacted with one another on a more regular basis than in societies of nuclear family members where individuals interact more with non-kin. societies comprised of nuclear families are more like my hypothetical janissary society above where the altruism genes that might’ve been selected for via kin selection instead fade away in the wash.

we have to be careful, though, in identifying nuclear family societies. the irish of today, for instance, are typically said to be a nuclear family society, but the extended family does still interact A LOT (i can tell you that from first-hand experience). same holds true for the greeks and, i suspect, the southern italians. i would say that these populations have residential nuclear families, but not fully atomized nuclear families which have infrequent contact with extended family (think: the english). the early anglo-saxons in england were also characterized by residential nuclear families — the extended family (the kindred) was still very important in that society. the individuals in a residential nuclear family society probably do interact with non-family more than individuals in a society structured around extended families or clans, but less so than a true nuclear family society.

the thought for the day then?: family types can also affect the selection for clannishness/nepotistic altruism.

that is all! (^_^)

previously: polygamy, family types, and the selection for clannishness and “l’explication de l’idéologie”

(note: comments do not require an email. irish nuclear family.)

16 Comments

  1. (What happened to the polygamy part? :p)

    “the thought for the day then?: family types can also affect the selection for clannishness/nepotistic altruism.”

    One would think that is almost a given, yes?

    I’m glad you’ve gotten this insight. This could be a key piece of your puzzle, and could help explain certain things, particularly with Eastern Europeans.

    Clearly you’re closer to solving the problem than anyone has come (it doesn’t hurt that so many others don’t even try). I think that the remaining loose ends will be explained by additional pieces to the theory.

    As well, it’s important to consider where family types come from (yes, I know you did before :p). Various forces, both endogenous and exogenous, imposed these family types on people. They themselves are not random – gene-culture co-evolution.

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  2. “he thing is, though: the individuals carrying certain versions (alleles) of nepotistic altruism genes need to direct their nepotistic behaviors towards other individuals carrying those same alleles, otherwise their actions will be for naught.”

    What if you’re thinking about the mechanism slightly wrong, due to W.E.I.R.D.O.?

    What if the mechanism of action for nepotistic altruism isn’t so much altruism towards insiders, as it’s generalized, often low-cost malice towards outsiders?

    In this social dynamic, accidentally forgetting to be malicious towards someone carrying the “wrong” nepotism allele isn’t much of a cost. There are plenty of unambiguous outsiders for which you won’t be able to exploit every opportunity for malice, either.

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  3. I think your analysis oversimplifies the problem greatly. First, consider the evolutionary selection for genes that cause one to defect from nepotistic altruism. Anytime a gene reducing it’s carrier’s inclination to offer nepotistic assistance shows up in a population where almost everyone has genes for nepotistic altruism. The carrier of the defecting gene will be more likely to reproduce than his non-defecting family members since he receives but does not have to give aid. Kin selection doesn’t favor the genes for nepotistic altruism here because the family members of the defectors are nepotistic altruists helping propagate the defecting gene package. On the other hand when almost everyone lacks the genetic package for nepotistic altruism kin selection will support it.

    So we should expect the situation to evolve into some kind of equilibrium between genetic packages that favor nepotistic altruism and those that defect. The effect of high levels of inbreeding is now much more murky. Inbreeding should speed the initial spread of genes for nepotistic altruism but it also speeds up the spread of defecting genes in a clan.

    Also it seems like it might matter what the factors influencing the underlying mutations that produce nepotistic altruism turn out to be, e.g., do you need rare versions of many genes to show the behavior and what happens if you have just some of those versions.

    I’m not saying the claim is wrong but I’m far from convinced that inbreeding obviously favors nepotistic altruism.

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  4. “The carrier of the defecting gene will be more likely to reproduce than his non-defecting family members since he receives but does not have to give aid.”

    Yes, the defector will do better than his family members, but will he do as well as the members of a clan in which no one defects? Clans with no defectors may find that they are able to bully and exploit clans weakened by defectors.

    Inbreeding doesn’t directly spread the altruistic alleles, it just creates a situation where families are more homogeneous. It clumps them. This results in altruistic alleles being able to help people with matching copies more often, thus increasing the fitness of such genes.

    Inbreeding would mean that people with defector alleles would find themselves more often clumped with relatives who are also defectors. This means that defection alleles are thus weaker, because they are less often used to exploit those without them. It also increases the risk that the family will fail totally (because it has a high proportion of defectors) and thus the men will find themselves with spears in their bodies as their women are sold into slavery.

    So in the same way that inbreeding can speed selection for altruism, it also speeds selection against defection. Of course aren’t they really just the same thing? Non-altruism alleles can be considered defector alleles.

    Reply

    1. @T:

      “Yes, the defector will do better than his family members, but will he do as well as the members of a clan in which no one defects? Clans with no defectors may find that they are able to bully and exploit clans weakened by defectors.”

      Don’t use group selection.

      Reply

  5. @Peter Gerdes:

    You’re assuming that no tendency to punish/shun defectors would eventually evolve to deal with such shirkers.

    Every family has its black sheep.

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  6. Another complementary theory is that greater mutational load may cause sense of differentiation from other groups. It happens quite naturally among the outsiders, who tend to be strongly universalist or at least non-clannish. Cultivate inter-group differences in long-term tends to favor the emergence of ideations of difference from the other groups and positive traits like greater intelligence, linked to this singular sense of belonging, can aggravate the situation. (and endogamy tend to cause common- non-de-novo mutation- accumulation).

    Another possibility, which is also complementary to its initial idea that you exposed in this post, is that little genetic diversity (both individually as collectively) can reproduce ”atavistic” behavioral characteristics or that were more common in the prehistoric past or at the beginning of the emergence of complex human societies, such as the propensity to magical thinking or ” religious ”, lower analytical and abstract intelligence, lower empathetic ability and less sense of individuality, on the assumption that despite the self-inflicted domestication humans have become, on average, more socially complex than, for example, at the time of ancient Egypt. (because of exposure of more advanced philosophical ideas rather than significant genotypic changes because for example if we compare the behavior of the Romans to the behavior of the Americans, it is likely we do not see big differences that could serve as prior explanation as to any new development human behavior non-memetic/natural in these last 2000 years).

    The inventions of the geniuses are all the time working against natural selection and in favor of artificial selection and evolution, through cultural exposure and little less about genetic changes.

    Creativity is regarded as a human weapon against conformity in relation to the common fatalistic landscape of the natural environment, where there will always be a great force that will eliminate ” weaker ”.

    However, we must begin to think of applying creativity and wisdom / convergent create-tivity also in an evolutionary perspective, that is, for ourselves and in order to avoid the biological weakening of our species, to become dependent on inventions of various natures created by exceptional individuals produced.

    Were 10,000 years of evolution … or domestication (* speculation *). Domesticated animals tend to have large genetic difference compared to wild strains from which they were produced. I looked for any link to this date our lord), but did not find and / or in collusion with my usual latent laziness.
    It would be interesting to accurately estimate ‘the size’ of this evolution. Indeed, major changes seem to have happened at the beginning of gracilization of the most cognitively advanced populations. After that, we only see ” panis etc circensis ” since Julius Caesar wore diapers or when Hercules was working (or when Jesus resurrected a bird).

    In other words, in terms of abstract thinking ability, most human beings who belong to the most cognitively advanced populations do not appear to be very different from the ancient Romans.

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  7. h*ck!

    Does this have an i and go with the preceding sentence, or does it have an e and go with the following sentence?

    I may not be the only double-cousin that wants to know. :-)

    Reply

  8. @HBDChick, your ‘theoretical society’ is similar to one of the American Plains Indian tribes, which gave the sons to the uncles families to raise. I don’t know if it was MB or FB. It was years (30?+) ago that I was told this in school, so the details are hazy, and the data could be incorrect. Uncles are not the perfect form that your unrelateds are. And, a nomadic people probably don’t have the sort of diversity available to them in marriage partners that others like say in NYC would have, so they may be marrying 3rd cousins or closer.
    The reason we were told that they did this is that uncles would be more strict.than a father would, insuring the overall survivability of the group because everyone knows how to live in the environment that they are in.

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  9. This explains Mormons and how every time I have a flat tire, 7 of them unbeknownst to each other inexplicably show up to help with lunch and sparkling cider.

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  10. Interesting study, but

    look little obvious

    and

    rationality is only apply for human beings, and not for other species.

    Rationality is a direct product of expanded (self) awareness or delayed (reflexive) instinctive responses. :)

    Rationality is a ideal/ quaaaaasi-utopy and without strong cultural and intrusive interventions will result in problems because will be anti-natural for almost all humans. Perfect rational humans are very rare or nonexistent. A benigne dictatorship (now we will search for good dictators, ;) ) would be ideal way to force rational culture.

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  11. I always struggle with the need to come up genetic causes for highly inbred groups being more clannish. Why can’t it be a natural response to these people really being closer? The social context reminds you all the time and the clannishness of others reinforces it.

    If I live in a large extended family with people whose family ties really, objectively are closer (Ie, my cousins and I share a lot more grandparents) doesn’t that naturally create a closer extended family I feel more nepotistic obligation to?

    Maybe there really is an important genetic feedback, but do we have a control? Do we have a cohort of Romani children who were adopted by ordinary Romanians and don’t know they are adopted, are they as clannish or corrupt as ordinary Romanians?

    It may be an important factor, but what is it we see that requires it as an explanation? Consanguinity and clannishness goes along with a tight social structure and control necessary for it to endure, it’s hard to see how one could isolate evidence for a genetic underpinning propping the behaviour up.

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  12. @Altai:

    “I always struggle with the need to come up genetic causes for highly inbred groups being more clannish. Why can’t it be a natural response to these people really being closer? The social context reminds you all the time and the clannishness of others reinforces it.”

    The laws of behavioral genetics.

    Particularly:

    1. All human behavioral traits are heritable.
    2. The effects of being raised in the same family are smaller than the effect of the genes (in reality, that effect in zero).

    Reply

  13. […] 2) populations where extended families are the norm. societies where two or three generations of families all stay together, work together, play together. viscous. plenty of opportunity for nepotistic behaviors to be selected for. on the other hand, societies of nuclear families where more distant relatives are seen only once a year on thanksgiving, and then only to argue, and where your your heir is your pet cat…not very viscous. (see:family types and the selection for nepotistic altruism.) […]

    Reply

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