italian iq and inbreeding

so, here are regional italian iq scores from lynn based on 2006 pisa scores against the averages of mean inbreeding coefficients for the same regions from 1960-64 (cavalli-sforza, et. al.). correlation is not causation, but i get a negative correlation of 0.85 (-0.85) which is pretty d*mn high.

i know, i know — i’m not comparing the exact same cohorts. but, if you think about it, the comparison is actually between parents and their children. the children are the kids who took the pisa tests in 2006 at age 15 (born in 1991) — and their parents are prolly the children of people who got married in the early 1960s. more-or-less. 1960-64 to 1991 is more like a generation-and-a-half than two generations, but it’s close. and we know that intelligence is in the genes, and we’re talking about families here, so….

like spain, higher iq scores are found to the north in italy, while the farther south you go, the farther south the test scores go. lynn suggests a couple of possible explanations for the differences including latitude and the presence of different populations (both in italy and spain in the medieval period you had germanic peoples settling the northern regions and muslims from north africa and beyond settling in the south). he doesn’t seem to have considered the different degrees of inbreeding between north and south (and possible inbreeding depression) as a potential cause. i’m not saying it’s the only reason behind the different iq scores, but it certainly could be a factor. btw — it was prolly the muslims who introduced strong inbreeding in southern italy as they did in southern spain.

here’s a map of the regions:

here are the data:

and, here are the numbers i used (from cavalli-sforza, et. al.) to get averages of the mean inbreeding coefficients for each region (the averages that i calculated are in bold):

previously: inbreeding in italy and increases in inbreeding in italy after the wars(?) and northern vs. southern spanish iq, redux

(note: comments do not require an email. typewriter penguin!)


  1. Don’t think the Muslims were long enough in Southern Italy to alter mating practices.
    These people were somehow left behind and regressed (despite being from the same kingdom as Aquinas himself!)


  2. I get the idea that constant coastal raids against southern Italians drove the people both physically inland, and mentally inward. They became very clannish and xenophobic. In the pre-rail era, being away from the coast meant another efficient means of transport was off limits.

    So the south Italians became sort of the equivalent of Virginia / Carolina mountain folk – supertraditional, quaint, with a reputation for violence and vengefulness. On the other hand, Julius Evola!

    Perhaps Islamic aggression is indirectly responsible for at least some inbreeding. (I wouldn’t think it was directly responsible for much because the region is solidly Catholic.)


  3. @ihtg – “Don’t think the Muslims were long enough in Southern Italy to alter mating practices.”

    well, they had a couple of hundred years to do so, so i think they might’ve. i don’t mean that they introduced endogamous mating to sicily — we’ve already seen that pre-medieval european populations happily inbred, so i’m assuming the populations on sicily were no different. i just mean (like i said) that they introduced the idea of strong inbreeding, i.e. marrying consistently within the father’s line, for instance.


  4. @olave – “So the south Italians became sort of the equivalent of Virginia / Carolina mountain folk….”

    yeah, being a bit isolated, like you said, can prolly lead to inbreeding. keep in mind, tho, that the scots-irish ancestors of the virginians/carolinans prolly brought cousin-marriage traditions with them from the old country. (~_^)

    @olave – “I wouldn’t think it was directly responsible for much because the region is solidly Catholic.”

    well, apparently, there’s catholic … and then there’s catholic. unlike most other catholics, sicilians do not have to get a dispensation from the church to marry their 1 1/2C or 2C (see the previous italy posts). LOTS o’ inbreeding in sicily (at least up until ’64 — don’t have any data for after that).


  5. Interesting. I am hardly an expert but I think inbreeding depression can only explain part of this clinal decline, a lot less than half. There are other genetic factors involved as in most cases of human biodiversity.


  6. @luke – well, i’m no expert, either! and i’m sure you’re prolly right — inbreeding depression prolly only contributes partially to this, if at all. i’m more suspicious about the different populations and whatever “genes for” smarts those groups contributed to italy and spain.

    at the same time, tho, i feel it’s kinda hard to tell (given the current level of knowledge about “genes for” intelligence) how much inbreeding has affected the iq of the arabs. i mean, they’ve been inbreeding consistently at high rates for a looooooong time. how much of their iq is due to “genes for” intelligence and how much is due to inbreeding? (and, obviously, how much is due to their environment.)


  7. @ihtg – “Christian Arabs can be very smart. How inbred are they?”

    generally less so than muslim arabs.

    in lebanon, for example, muslims in beirut in 1983-84 had a 29.6% consanguinity rate, while christians had a 16.5% rate. muslim arabs (non-bedouin) in israel in 1990-92 had a 32.1% consanguinity rate, while christians had a 20.6% rate. this is a pattern repeated throughout the middle east. i know, too, that the coptic christians in egypt tend to marry their second cousins more than their first, unlike the muslims in egypt.

    so, yeah, christian arabs inbreed, but less than muslim arabs.

    i don’t know what the numbers look like historically, tho. like going back to the middle ages, i mean.


  8. An interesting thing about inbreeding and tribalism is that there’s a particular type of tribal society, where your cousins are so close to you that they’re considered to be like siblings.
    In that case, the tribalism seems to actually prevent endogamy. That’s how it works in Ethiopia, for instance.


  9. @ihtg – yeah, i don’t know much about the ethiopians, but iirc their tradition is something like you can’t marry up to third cousins. ah, and as i check wikipedia, i see that it says there that marriage within the sixth cousin range was/is frowned upon.

    ethiopia is a majority christian country, so these prohibitions sound to me like echos of the catholic church’s banning of cousin marriage in europe. i’d bet that these marriage traditions in ethiopia have something to do with the christian church there. interestingly, many ethiopian muslims seem to avoid cousin marriage, too.


  10. @random – yeah, ok. ’cause we wouldn’t wanna — you know — keep thinking about the question from different angles to make sure we haven’t missed anything now would we?


  11. I’m years late to this post, but I haven’t been on the internet in days cuz I’m desperately trying to finish an academic project under a deadline.

    Thanks so much for posting the consanguinity rates on Italy by region (Italy’s a big part of my project), for me personally they will be a huge help. I have scads of info. on the diff. regions of Italy I would love to post here and will try to as soon as I have time.

    A note: People who wander onto information-sharing blogs such as these and attempt to use derision as a tool to stop the information-sharing tend to be people made profoundly uncomfortable by imagining the possible change in world-view that the results of such information-sharing might impose upon them.


  12. @m.g. – “I’m years late to this post, but I haven’t been on the internet in days cuz I’m desperately trying to finish an academic project under a deadline.”

    get your work done first! the internet will (prolly) be here when you’re finished. (^_^)

    i look forward to reading what you’ve got on italy! btw, did you see (in another post here) that i found the cavalli-sforza book where this data came from on google books? you can at least skim through there if it interests you — and, of course, you can prolly get it at/via your academic library.


  13. Yes, I jumped on that Cavalli-Sforza book and all his tables, a huge help. I’m studying cultural values in diff. groups in Europe to see how they relate to economic performance, and Italy is such a great case study cuz on any indicator you look at, the North and the South are like two different planets. Will post much more soon. Thanks again!


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