evo psych in need of a little hbd?

dennis mangan has a post over @altright about some recent research from sveeeeeden which appears to refute the “cinderella effect.” (see also kanazawa.)

and maybe it does, which would be real interesting.

the sveeeeedish researchers found that the step-kids and real-kids they looked at were killed at pretty much the same rate, and that the common thread running through all the cases was that the step-dads had a violent, criminial history. this latter part doesn’t seem surprising. you’d think most murderous people are violent people, so it’s not a big shocker that these low-lifes had violent histories.

but i think the sveeeeedish researchers mighta overlooked something.

all of the previous research done on the cinderella effect — at least the research referenced by the sveeeeedish researchers — has been about north american (u.s. & canukian) and engrish families [see here, here and here]. the currect research by the sveeeeedish researchers relates to — you guessed it! — sveeeeedish families.

so, gee. might there be any differences between the sveeeeedish families and, say, americun families? any differences at all? hmmmmm. i wonder….

well, the first thing that pops into my head is that the sveeeeedish families are likely more homogeneous** than the americun families. and by homogeneous i mean genetically homogeneous. u know — sveeeeedes mating with other sveeeeedes unlike in the states where sveeeeedes might mate with germans or italians or irish or blacks or, worst of all, some of those norveeeeegians!

why should that matter?

well, the whole point here is that step-parents are less genetically related to their step-kids than to their real-kids and are, therefore, more likely to kill their step-kids than their real-kids (if they’re gonna kill them at all, that is). killing your real-kids does NOT help with your inclusive fitness. killing your step-kids — sure. why support some other guy’s|woman’s kids? that’s no good for your genes.

but what if the population is very homogeneous genetically speaking? what if the individuals across a population are quite alike in their genetic make-up? what if the population has, for a very long time, avoided inbreeding on a very local basis (unlike some other populations which have become very “tribal” as a result of their localized inbreeding)?

in such a society in which individuals are quite alike genetically you’d expect to see lots of altruism across the board — more than in, say, afghanistan. you wouldn’t be surprised, for example, if they were quite happy to share with everyone else in their society ’cause they’d be “thinking”, hey, all those other people share a lot of my genes anyway! and if the individuals are quite alike genetically, then you’d also think they’d be, well, more interchangeable.

and then, on the flip-side, would it matter soooo much if you killed your step-kid or your own-kid? meh. not so much.

obviously it would still matter, i think, but maybe not soooo much. (especially not so much if you’re a violent, low-iq low-life.) ’cause they’re kinda interchangeable, remember?

it certainly wouldn’t matter so much as if your step-kids are actually german-american while you’re sveeeeedish-american. or if your step-kids are italian-american while you’re irish-american. maybe then it makes even more sense to get rid of your step-kids, if you’re so inclined.

i suspect that there are different rates of filicide by natural- and step-parents in different populations due to varying “levels of relatedness” within different populations. the more unrelated you are to your step-kid, the more it makes sense to not favor that kid or even to get rid of him altogether.

that’s just a thought, of course.

in any case, a little hbd in evolutionary psychology might go a long way. evo psych needs to shake off the cosmides & toby notion that all of our drives evolved when our ancestors were hunters & gatherers. we’ve moved past that now and evolutionary psychologists need to start taking human biodiversity into account more often.

**well, the sveeeeedish researchers looked at homicides of kids between 1965 and 2009. in the earlier part of their sample i’d guess that these families were pretty much all swedish since sweden has only recently become a multi-cultural society. as for the last decade, i dunno. would be interesting to know the ethnic|genetic backgrounds there.

update 01/17: see also killing kids & step-kids, part ii

(note: comments do not require an email.)


  1. Is there evidence for more genetic variation among Pashtuns than Swedes? The more I think about it, the more it seems that a gene to kill step-children would be naturally selected even given uniformity among the rest of the genome (imagine the kid-killing gene is a new mutation in a population of clones). So the norm of reaction issue with Swedes just being nicer may suffice.


  2. @tggp – “Is there evidence for more genetic variation among Pashtuns than Swedes?”

    well, if you’re lookin’ for full genome sequences of the swedish and pashtun populations to compare, then no. not yet anyway. (~_^)

    there is, however, data on the coefficents of inbreeding for the two populations, altho not for the same time period:

    afghanistan 1995 (nangarhar & kunar provinces, majority pashtun): coefficient of inbreeding = 0.0332 (i.e. pretty high).

    sweden 1946/50 (don’t think the swedes have started inbreeding at greater rates since): coefficient of inbreeding = 0.0003.

    @tggp – “The more I think about it, the more it seems that a gene to kill step-children would be naturally selected even given uniformity among the rest of the genome (imagine the kid-killing gene is a new mutation in a population of clones). So the norm of reaction issue with Swedes just being nicer may suffice.”

    absolutely. it makes sense to get rid of your step-kids if you can. or at least to favor your real, biological kids over any step-kids.

    and maybe swedes are just nicer. that could very well be. maybe an adaptation to surviving long, cold winters. ??

    my suggestion was simply that because the swedes are not so inbred, the members of that population are more “interchangeable” and so it might not matter sooooo much to kill your real kid vs. your step-kid as it would in an inbred society.

    in a follow-up post i put it like this:

    “i think of it this way. if you marry your cousin, your kids are not just your kids, they’re your cousins, too. so, imagine the sentiments you have towards your kids — and then imagine the sentiments you have towards your cousins — and add them together. yes, i know, it might not work out mathematically exactly like that, but you get my point. peoples who inbreed on a regular basis must feel more strongly attached to their relatives ’cause they are genetically more like them than most of us westerners are to our families.”


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