viscous populations and the selection for altruistic behaviors

part of william hamilton‘s theory of inclusive fitness/kin selection, which explains how altruism ever could’ve arisen at all (altruism here having a very specific definition), is that it should be possible for genes for altruism to be selected for if close kin interact regularly. kin don’t need to recognize one another for altruism to be selected for. as long as closely related individuals don’t move far from one another — that is, if a population is viscous — selection for altruism might happen.

i can’t see why this couldn’t also apply to lesser forms of altruism, not just the kind where you sacrifice your life for two brothers or eight cousins. you know what i mean. like: reciprocal altruism or nepotistic altruism. or just pro-social behaviors. whatever you want to call them. seems to me that nepotistic behaviors ought to be selected for more easily in viscous populations (if they increase fitness, of course).

and some populations are more viscous than others:

1) inbreeding populations where close relatives marry frequently over the long-term. mating with relatives must be highly viscous [insert sweaty/sticky incest joke here]. not only do the individual members of the population likely interact fairly regularly (can depend on your mating pattern), they pass many of the genes they share in common on to the next generations — who then also interact and mate. that’s what i call viscous! and, as you all know by now, some human populations inbreed more than others, and some have been doing so for longer than others. and vice versa. (see: entire blog.)

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.)

3) socio-economic systems which push for close relatives to remain together rather than dispersing. if that sounds vague, that’s ’cause it is. sorry. i haven’t thought through it all yet. i do have an example of the opposite for you — a socio-economic system which pushed for close relatives to disperse — and that is the post-manorialism one of northwest europe. already by the 1500s, it was typical for individuals in northwest europe to leave home at a young age (as teenagers) and live and work elsewhere — often quite long distances away (several towns over) — before marrying. then it was not unusual for them to marry someone from their new locale. not viscous. conversely, many societies outside of the hajnal line (northwest europe) have had systems which encouraged the opposite.

food for thought.

(note: comments do not require an email. one of my favorite viscous food for thought!)



  1. Just to clarify, am I approximately right in thinking that translated into Todd’s terminology, this would look somethnig like;

    2 & 3 = Exagamous communitarian family

    1, 2, & 3 = Endogamous communitarian family


  2. Lovely post, which wraps up many threads (was going to say loose threads, but woven threads is closer to the mark). On point 3, I think the contemporary “Western” trend is towards sending your children to the place of greatest competition, which is also the place where they have fewest family connections, so they are tested and then mate with a similarly displaced person.


  3. Contrary to the idea ‘outbreeding produces mechanically higher extra-groups altruism’ I’m preferring the idea that outbreeding increase specially the behavioral plasticity, producing a wider range of possible micro adaptations (or conformities) where the extra-group altruism will be one of this possibilities.

    However, it is important to think about the social structures, societies are macro-architectures or overlapping of human sociotypes. You can modify these parts and produce a new hierarchy. There has always been a hierarchy of priorities and there are some groups who are responsible to communicate the new or common guidelines to the rest, like ”to play telephone or Chinese whispers” game.

    Who screams louder, and have state support, it is what will dictate the rules. (Unfortunately, this is what happens)

    Today the Western cultural epicenter was shifted to the romantic cicadas (and wolfes) on the ideological left. What many call the ‘brainwashing’. You have those who are consistently in a political side / evolutionary / transcendental and you have those who are subconscious micro-adaptationist (or just ” ignorant ” I’m still in doubt if these people think about its attitudes quite consciously, that is, they are just ignorant, comparatively speaking, they are doing their best… and for us, it’s just stupid).

    I think altruism (loosely speaking) is one of those universal traits of human beings, which is not to be present in all of them, but in all its populations. of course.

    I do not completely buy the idea of ‘innate and quasi-global pathological altruism’ ‘among Europeans. Two monstruous world wars (fratricide) does not seem to me ” pathologically altruistic ”, it is pathological for sure, but absolutely far to be ”altruistic”.

    Again, people on the (modern) left, were heave to positions of importance / highlight and how are they who are des(organizing) the society then the other most of the time will only micro-adapt to this new situations, opportunistically.

    To understand what is happening in Europe, you need to study on the psychology of the masses, and I think this trend is universal among humans. Most humans are susceptible to act as useful idiots and they are/do in the most cases.


  4. Modeling shows that altruism can be stable with low dispersion, local interaction and especially low (i.e., tribal level) N (e.g., Hartshorn, et al. 2013), especially when policing/punishment is added (e.g., Bausch, 2014) and group sensitive behavioral strategies are allowed (e.g., Schonmann, et al. 2012; Chen et al. 2014.) Of course, non-altruistic (i.e., non fitness reducing) favoritism a.k.a homophily would be viable in large populations. To note, I asked Harpending about the issue and he noted that by “ethnic nepotism” he had in mind something like ethnophily, not a fitness costing behavior.


  5. Jayman will disagree if I understand him correctly. Myself I tend to agree, though it is questionable how long (how many generations) those alleles would survive at high frequency in a much larger population group that is directly descended. The soldiers on both sides in the American Civil War certainly laid down their lives in large numbers — would/could that have had anything to do such alleles?


  6. First time I read “viscous” in context of human families :D

    Commenting just to show my appreciation of your work.

    Strange thing, i got “sorry, this comment could not be posted”


  7. So ,that explains why whites are full of SUICIDAL altruism now.Or at least liberal globalist buffoons.


  8. “So ,that explains why whites are full of SUICIDAL altruism now.Or at least liberal globalist buffoons.”

    Had the same idea, just hesitate a bit what the “explain” part is concerned.

    Wouldn’t Australia and – – Japan be counter-examples policy-wise?


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