more on ibd and historic mating patterns in europe

t (thanks, t!) points me to this article (this story seems to be making the rounds this a.m.):

“All Europeans are related if you go back just 1,000 years, scientists say”

“A genetic survey concludes that all Europeans living today are related to the same set of ancestors who lived 1,000 years ago….

“The researchers were surprised to find that even individuals living as far apart as Britain and Turkey shared a chunk of genetic material 20 percent of the time. To explain that degree of genetic commonality, the researchers say those pairs of individuals would have to have a huge number of common genealogical ancestors 1,000 years ago — a number that takes in everyone who was alive in Europe back then….”

the results of the survey being discussed here have just been published on plos biology: The Geography of Recent Genetic Ancestry across Europe.

before i go on to discuss the bits i’m interested in (the identity by descent, or ibd, rates that they found), i just want to quote something from the plos article related to this business that all europeans share the same set of ancestors that lived 1,000 years ago. yes, we do, but keep in mind that:

“[S]omeone in Spain may be related to an ancestor in the Iberian peninsula through perhaps 1,000 different routes back through the pedigree, but to an ancestor in the Baltic region by only 10 different routes, so that the probability that this Spanish individual inherited genetic material from the Iberian ancestor is roughly 100 times higher. This allows the amount of genetic material shared by pairs of extant individuals to vary even if the set of ancestors is constant.”

in other words, some europeans are more related to one another than to others. but we all knew that already.

anyway…

this is the same (really awesome!) study done by ralph and coop that i posted about last year here and here. (oh, and here, too.) some of the data were available online back then after the researchers had given a presentation somewhere or other [pdf].

i’m interested in ibd data since they, like runs of homozygosity (roh), can give us some clues about how inbred or outbred populations are. it’s not a clear-cut interpretation, though, because both ibd and roh can be affected by other population genetic processes like bottlenecks and migration and simply population size (and probably other things, too, about which i am blissfully ignorant), so one has to make some educated inferences and guesses.

unfortunately, the authors don’t seem to have included in the plos publication the following illustration from their earlier presentation (unless it’s buried in the supplemental data — i didn’t see it there, but there’s a LOT of supplemental data files). that’s a shame, because it’s one of the most interesting:

the map shows the mean ibd rates for each of the european populations studied (the mean length of the blocks was >1 cM). individuals in the populations with higher mean ibd rates (bigger circles) share more identical stretches of their dna with their fellow countrymen than those in populations with low mean ibd rates. lots of outbreeding can lower the amount and lengths of ibd blocks in a population. as i posted previously, i think you can see the historic (since the early medieval period) outbreeding patterns of western europeans in the low mean ibd rates in western europe. this pattern is even clearer when you add the hajnal line to the map (the hajnal line being a good indicator of the geographical limits of the roman catholic church’s/secular authorities’ push to, amongst other things, ban cousin marriage in the medieval period).

now, here from the plos paper is a table indicating “mean number of IBD blocks shared by a pair of individuals from that population (‘self’), and mean IBD rate averaged across all other populations (‘other’)”:

i put the mean ibd “self” (i.e. within a population) numbers on a map and added the hajnal line. (note that the “mean length of these blocks was 2.5 cM, the median was 2.1 cM, and the 25th and 75th quantiles are 1.5 cM and 2.9 cM, respectively”.) [click on map for LARGER view.]:

ralph and coop suggest that the rates are so high in eastern europe, and particularly the balkans, because of the fairly recent slavic migration into the area and the fact that the slavs settled in relatively uninhabited areas. they further suggest that the germanic migrations into western europe are not so apparent in the ibd rates since these were already heavily populated areas and maybe even that the germanics were an heterogeneous group to start off with. those are really good theories (especially the one about the slavs), and i think that — yeah — we are probably seeing signals of those migrations in these data. however, once again, i think you can also see the long-term historic inbreeding/outbreeding (greater cousin marriage vs. little cousin marriage) mating patterns of european populations reflected in the ibd rates. (see “mating patterns in europe series” below ↓ in left-hand column for more details on all the mating patterns which i mention in the next few paragraphs.)

my “core europeans” — the english, the french, the belgians, the dutch, the germans, the north italians (not so much the ones in the alps, though), and to some extent the swiss and scandinavians — have the longest history of outbreeding (i.e. avoiding cousin marriage) in europe beginning in the early medieval period — and they have the lowest ibd rates. the rates are a bit higher for scandinavia since they converted to christianity later and, thus, didn’t adopt the cousin marriage bans until later. same with the irish and the scots (in fact, i think that highland scotland should be indicated as being outside the hajnal line, but that’s a discussion for another day). that the netherlands has a higher ibd rate than neighboring belgium and germany also makes sense if you know about the (probable) late adoption of the cousin marriage bans by those living in the marshes like the ditmarsians.

the ibd rates are higher east of the hajnal line and that, too, makes sense if you know that the eastern orthodox church was both later at instituting and less consistent in enforcing cousin marriage bans. the very high rates in albania and kosovo are probably related to the fact that these populations include a majority of muslims and that muslims typically have no bans on marrying cousins (while the albanians, and likely the kosovans [or whatever you want to call them!], have probably avoided paternal cousin marriage, maternal cousin marriage seems to have been an option, possibly even preferred).

the very low rate in italy is puzzling and, as i have said elsewhere, may have to do with the fact that, as the authors suggest, italy has experienced so many influxes of different populations. alternatively, it may have to do with a sampling bias (i.e. where did the italian samples come from? the more outbred north, or the more inbred south?).

the authors also broke down the ibd rates by several european regions of their own devising: “These five groupings are defined as: Europe ‘E,’ lying to the east of Germany and Austria; Europe ‘N,’ lying to the north of Germany and Poland; Europe ‘W,’ to the west of Germany and Austria (inclusive); the Iberian and Italian peninsulas ‘I’; and Turkey/Cyprus ‘TC.’” here is their table:

i made a map — and added the hajnal line (of course!):

again, there’s the east-west divide that i’ve pointed out before and which, i think, corresponds to the edge of the hajnal line. there also seems to be a north-south divide, which is apparent on both sides of the east-west (fuzzy) border, and which may have to do with long-standing lower population densities in northern europe. (that does make sense if you think about it — smaller populations inevitably experience closer matings or greater “inbreeding.”)

mating patterns matter! particularly long-term mating patterns. i think so anyway.

previously: ibd and historic mating patterns in europe and ibd rates for europe and the hajnal line and ibd rates and kindreds in germanic populations and russians, eastern europeans, runs of homozygosity (roh), and inbreeding and western europeans, runs of homozygosity (roh), and outbreeding and runs of homozygosity and inbreeding (and outbreeding) and runs of homozygosity again

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historic european homicide rates … and the hajnal line

here’s another map of europe — from steven pinker’s Better Angels:

“Figure 3-8. Geography of homicide in Europe, late 19th and early 21st centuries [i've only shown the 19th century map here - h.chick]. Sources: Late 19th century (1880-1900): Eisner, 2003.”

now here’s the same map with the hajnal line added. oh … oops!:

what i’ve been wanting to see is a map showing the reduction of homicide rates in europe over time. eisner has shown that the homicide rates didn’t drop all at once — they started dropping the earliest in england, belgium/netherlands, germany and switzerland — later scandinavia — and, much later, italy and the rest of peripheral europe (see this post for more details and nifty charts). here’s pinker summarizing eisner’s findings (from chapter 3 of Better Angels):

“[F]rom the 13th century to the 20th, homicide in various parts of England plummeted by a factor of ten, fifty, and in some cases a hundred — for example, from 110 homicides per 100,000 people per year in the 14th-century Oxford to less than 1 homicide per 100,000 in mid-20th-century London….

“Were the English unusual among Europeans in gradually refraining from murder? Eisner looked at other Western European countries for which criminologists had compiled homicide data. [T]he results were similar. Scandinavians needed a couple of additional centuries before they thought the better of killing each other, and Italians didn’t get serious about it until the 19th century. But by the 20th century the annual homicide rate of every Western European country had fallen into a narrow band centered on 1 per 100,000….

“The Civilizing Process spread not only downward along the socioeconomic scale but outward across the geographic scale, from a Western European epicenter…. England was the first to pacify itself, followed closely by Germany and the Low Countries. Figure 3-8 [the one i half-posted above - h.chick] plots this outward ripple on maps of Europe in the late 19th and early 21st centuries.

“In the late 1800s, Europe had a peaceable bull’s-eye in the northern industrialized countries (Great Britain, France, Germany, Denmark, and the Low Countries), bordered by slightly stroppier Ireland, Austria-Hungary, and Finland, surrounded in turn by still more violent Spain, Italy, Greece, and the Slavic countries. Today the peaceable center has swelled to encompass all of Western and Central Europe, but a gradient of lawlessness extending to Eastern Europe and the mountainous Balkans is still visible.”

i wanted to see THAT on a map, so i drew one (NOT with crayons, although it kinda looks like it…). lighter shades=earlier drop in homicide rates; darker shades=later drop. i’ve indicated the century in which homicide rates began to drop for each region. and i’ve drawn in the hajnal line:

finally, a footnote from pinker:

“There are gradients within each of these countries as well: the hinterlands and mountains remained violent long after the urbanized and densely farmed centers had calmed down. Clan warfare was endemic to the Scottish highlands until the 18th century, and to Sardinia, Sicily, Montenegro, and other parts of the Balkans until the 20th.”

previously: ibd rates for europe and the hajnal line and outbreeding, self-control and lethal violence and what pinker missed

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ibd rates for europe and the hajnal line

*update below*

remember this map from ralph & coop [pdf]?:

those are the mean ibd (identity by descent) rates for various populations in europe. the bigger the circle, the greater the number of ibd blocks larger than 1cM in length shared in common between each populations’ members. so, the larger the circles, the more segments of dna the individuals within those population share in common — i.e. the more alike they are genetically.

well, i never added the hajnal line to that map like i usually like to do for any map of europe that lands on my desktop (see here and here for examples). how remiss of me! (recall that populations within the hajnal line have had a historic tendency to marry late.)

i thought i’d better rectify this situation … so, here it is! mean ibd rates for europe PLUS the hajnal line. enjoy!:

update: see also jayman’s More on Farming and Inheritance Systems – Part I: IQ.

previously: ibd and historic mating patterns in europe and behind the hajnal line and todd’s family systems and the hajnal line

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sex and “the other”

“the other” is a shapeless concept in anthropology/the social sciences which i never quite understood — prolly ’cause the anthropologists/social scientists don’t understand it themselves. it’s got something to do with how we react to people who are unlike ourselves somehow or in some way … different headdresses or tattoos or taste in music … or something like that. it might’ve been a useful concept if they’d looked at it from the p.o.v. of genetics, but they mostly didn’t so … never mind….

anyway.

in light of the scandals in rotherham, i thought i’d take some time out from the regularly scheduled program to present a couple of very vague ideas i have related to sex and genetic relatedness between individuals/groups. i haven’t really thought through these ideas, so they’re very vague. don’t say i didn’t warn you. (also, could be that actual scientists have already thought through/done lots of research on all of these already and i’m not aware of it. if so, just ignore me.)

vague thought number one:

if the prime directive is to reproduce your genes (or at least those that would have an effect in this case) as much as possible, one tactic in achieving that goal might be to reduce how much your competitors — those individuals unrelated to you who don’t share your genes — manage to reproduce their genes. you could do that by a) killing them, and/or b) preventing them from reproducing in some other way.

one way to prevent “the other” guys from reproducing (so much) would be to mate as much as possible with, if you imagine two neighboring tribes, their usual mates. then, not only do you reduce the actual reproduction of “the other” guys’ genes, you also increase your own and spread your genes even that much further than you would’ve if you just stuck to the members of your own tribe. so it’s possible — possible — then that a special drive for mating with “the other” could’ve been something that was selected for ’cause it might’ve paid off.

however, you would think this would be a better strategy for men than for women since reproduction for human females is such a long, drawn-out, costly affair, whereas men can just spread their seed hither and thither without a care in the world. a drive for sex with “the other” might, then, be stronger in men than in women, and might even result in a certain amount of sexual coercion (to put it nicely) since the women don’t really want to engage in this sex with “the other” so much. and this coercion might be applied more often to unrelated/unlike females than to related/like females a la ghengis khan and his band of literal brothers sweeping across eurasia raping and pillaging wherever they went (that’d be one of the more extreme examples — extreme in terms of behaviors exhibited and in terms of success).
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vague thought number two:

in my world of inbred populations, familial altruism rules the day because it pays more — inclusive fitness-wise — to be altruistic towards your family members, since you share an inordinate number of genes with them compared to non-family members. perhaps, too, in an inbred society it would also pay more to mate with “the other” (as described above) if and when you could since, in an inbred society, the different extended families/clans are less related to one another than families in an outbred society. by mating with your unrelated neighbor’s sister, you’re (heh) screwing him genetically more than a guy in an outbred society would do to his neighbor. in other words, perhaps a stronger drive to mate with “the other” could be selected for in inbred societies because the effect of “vague thought number one” would be amplified. (perhaps this is why peoples in the arab world/middle east cover their women up in burkas — for their own protection just like they often say!)
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vague thought number three:

glenn daniel wilson has suggested that rape is/was a reproductive strategy of — i guess the gameboyz would call them beta males — guys who didn’t have access to females ’cause some alpha males had all or most of the access. maybe, then, the drive to rape is a response to polygamy. maybe. if so, that would certainly seem to fit the arab world and might explain why they are overly protective of their women (burkas, purdah). might even explain what happened in rotherham. i have to admit, i’m not 100% convinced by this one. i think it might be part of the explanation, but not the sole one.
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vague thought number four:

i’ve been meaning to do a post on this, but just haven’t gotten around to it, so i’ll just tack it on here. sex drives and the hajnal line — something which jayman mentioned in the comments here.

you’ve probably all seen henry harpending and greg cochran’s recent (very cool!) discussions about fathers’ ages and mutation rates (most recent example here). my question, wrt the late marriage trend in western europe for both men and women, is: has there been any selection for behaviors related to these late marriages?

if — if — over the last few hundred years, those nw europeans who married (i.e. mated) at a later age were more successful at leaving their genes behind than those who married young, were certain behavioral traits related to this selected for? greater ability to delay gratification, for instance (in this case sexual gratification!)? relatively lower libido (“no sex, please, we’re british!” — see also monty python)? other traits i haven’t thought of?

like jayman said in his comment, in most of the world even today — and in many more parts up until very recently — a 14, 15, 16 year-old girl is/was considered very marriable/matable. maybe nw europeans feel that relatively less so. dunno.

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the al-hajnal line?

(<< i know. i've got a double definite there!)

in How unique is the Western European marriage pattern? A comparison of nuptiality in historical Europe and the contemporary Arab world [pdf], engelen and puschmann have found that, in the arab world today, both men and women are marrying at a very late age on average — kinda like nw europe behind the hajnal line (click on charts for LARGER view):

the authors reckon that men and women in the middle east/north africa/arab world are putting off marriage ’til later nowadays simply because it’s expensive to get married and start a family in today’s world (sounds familiar!). i wonder how long this delayed marriage pattern will last in this part of the world?

one way that the arab world’s new marriage pattern is unlike what goes on behind the hajnal line is that there is still (near) universal marriage in the arab world. everyone’s getting married late — but everyone is getting married [pg. 14]:

“There are also interesting differences. Especially Arab men in the age category 25‐29 have less chance of being married in 2000 than their European counterpart one century earlier. Since only very few men remain single at age 45‐49, this points to a very high age at marriage. Women in Arab countries marry younger than European women did and by the time menopause sets in, almost all have married. The convergence between historic Europe and contemporary Arabic nations thus only applies to the age at marriage. Permanent celibacy remains a difference between the two societies. Nevertheless there are signs that in the near future Arab societies may also see a rise in the never marrying proportions of the population. After all, in countries like Bahrain, Lebanon and Kuwait marriage show already relatively high percentages of celibates in the age‐category 45‐49.”

previously: behind the hajnal line

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medieval manoralism and the hajnal line

so instead of watching the super bowl, i made you guys this map:

i bet you’re thinking that that’s the hajnal line (again). but it’s not! (or is it?) no — that is a map of the spread and extent of manorialism during the medieval period as drawn by moi and based on the info in my friend, mitterauer’s, “Why Europe?”.

i know! it looks just like the hajnal line!:

manorialism got started amongst the franks in austrasia (big green blob on the map) “around the middle of the seventh century, or somewhat earlier.” it spread westwards and southwards along with the expansion of the carolingian empire and the ostsiedlung. and it seems to have been brought to britain by the anglo-saxons; there’s evidence in the law tracts for manors in wessex (other green blob on the map) by the end of the ninth century.

the farthest east the manor system made it was to the eastern limits of hajnal’s line — mitterauer is very clear about that boundary. he is also very clear that manorialism wasn’t found in ireland (the normans tried, but didn’t really succeed), scotland or wales. some pockets on the continent also missed out on manorialism, like frisia.

mitterauer was less specific about the boundaries of manorialism to the south. definitely greece and the balkans were completely left out. he refers to the southern part of the iberian peninsula and southern italy, but that’s all he said, so my lines in those cases are just shots in the dark.

it took some time for manorialism to spread as far east as it did — there were efforts to install the manor system in places like poland, belarus and the baltic area in the late middle ages and, in some cases, as late as the early modern period, so whatever evolutionary effects the manor system might’ve had on populations (here and here, for example), they had less time to work on eastern europeans than westerners. (same goes for christianity.)

there’s been debate about how old the hajnal line is — just how long have both male and female europeans been putting off marriage into their later years (mid-20s+)? in “Germania,” tacitus apparently reported that the germans married late…

“Sera iuuenum uenus, eoque inexhausta pubertas. Nec uirgines festinantur; eadem iuuenta, similis proceritas….”

…which google-translates as: “Late youths rigorous, and compared puberty. Not virgins hurried into marriage, the young man, and a similar stature….” which may or may not mean that tacitus thought both men and women married late in germanic society. in any case, tacitus was working from secondary sources at best and so may not have had the most accurate info. he was also trying to shame his fellow romans into shaping up by offering as comparison these well behaved germans, so … buyer beware.

on the other hand, archaeological evidence from anglo-saxon graves indicates that women married young — probably right around when they hit puberty, which is pretty normal for most human societies [pg. 107]:

“The evidence from the Anglo-Saxon cemetaries shows that teenage girls were often buried in forms of dress that made them indistinguishable from adult women from about the age of twelve onwards. That would fit with a predictable, marriageable age from the very young teens onwards, which we know of from comparable societies.”

going by the archaeological evidence, and what would otherwise be an extraordinary coincidence of the boundaries of manorialism and the hajnal line being almost exactly the same, i would happily bet that the late marriage of western europeans originated in the medieval period. mitterauer certainly makes the connection between manorialism and the hajnal line in the east explicit, but he doesn’t consider what the evolutionary significances of manorialism for european populations might have been (not that there’s anything wrong with that! he’s a historian, after all!).

my working theories are (see also previous posts below): 1) that manorialism, along with the church’s bans on close marriage, contributed to the loosening of the genetic ties of european extended families/clans/tribes; and 2) that manorialism contributed to the late marriage practices of western europeans, and even possibly (probably) selected for individuals who were able to put marriage off.

with regard to the first point, manorialism contributed to the breakdown of europe’s clans/tribes since the manor system demanded that family units be no larger than nuclear in size. clans or tribes just didn’t fit the system. the system also contributed to the loosening of genetic ties since a peasant had to get permission from the lord of the manor to marry rather than just marry his kissin’ cousin. in fact, it would’ve been in the lords’ interests to break the power of clans or tribes ’cause they were just trouble and, as manorialism expanded, the lords would’ve been looking for a compliant, dedicated workforce — not a bunch of extended family members dedicated first and foremost to each other.

secondly, which peasants succeeded in the world of the manor? presumably hard-working, maybe kinda intelligent — but how about also able to hold off on the urge to mate until one was well-established? (sound like any group of people we know?)

under the manor system, you didn’t get to rent a farm from the lord — i.e. make a living — until he was good and ready to let you a farm. and you couldn’t marry until you had some land to work. those individuals who couldn’t hold off, reproductively speaking, until they were in a position to marry would’ve lost out — they wouldn’t have been considered responsible enough to be a part of the lord’s manor — or, at least, they would’ve wound up somewhere at the bottom of the heap — selected out.

i think it’s reasonable to assume that the lords of the manors would’ve selected responsible, hard-working, bright men and women to work their lands (they were looking for a profit, after all) — and their selection practices would’ve, in turn, selected — in the evolutionary sense — for certain types of individuals within western european society. and these types of individuals — hard-working, bright, able to delay their own gratification — would’ve carried these traits forward once manoralism disappeared and europeans became independent farmers in their own right. in fact, maybe they never would’ve managed that if their ancestors hadn’t gone through the manorialism sieve in the first place.

it’s an idea, anyway.

and, finally:

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(^_^)

previously: medieval manoralism and genetic relatedness and assortative mating and the selection for high iq in (some) medieval european populations?

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todd’s family systems and the hajnal line

a couple of weeks ago, i stuck the hajnal line on top of jayman’s map of average iqs in europe to see what would happen. nobody got hurt (i think). (~_^)

today i wondered what would happen if i tried the same thing only this time with m.g.’s terrific map of emmanuel todd’s traditional family systems of europe:

the two things that stand out to me are:

- the absolute nuclear family does not happen anywhere outside the hajnal line (in europe, anyway).
- the authoritarian (“stem”) family mostly happens within the boundaries of the hajnal line.

on that second point, there are some outliers — ireland, the southern tip of finland, some bits of slovakia and hungary — but mostly todd’s authoritarian family occurs within the hajnal line limits. (the southern tip of finland looks like the hajnal line should just be moved a bit to the north….)

i don’t know what any of this means — if it means anything — but i just thought i’d share. (^_^)

edit (see comments below):

“anglian homelands” >>

anglo-saxons in britain >>

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behind the hajnal line

**update below**

here’s a map created by jayman of average european iqs (taken from here), and on top of it i’ve added the hajnal line:

the populations behind the hajnal line (i.e. the core of europe) are characterized by:

- late marriages (present since at least the early medieval period)
- small family sizes (nuclear or stem families versus extended families; also present since at least the early medieval period)
- higher average iqs, in general, than populations in the periphery of europe (see map)
- strong future time orientation, strong societal collectivism, strong preference for rules and order (Ordnung!), strong drive to succeed
- being more civic than populations in the periphery of europe

why?

well, maybe it’s just ’cause these populations are mostly germanic, or at least had a strong-ish germanic presence in their territory at some time in the past. maybe this is just an example of ice peoples who evolved high iqs and a lot of other neat traits ’cause they survived for a long time in adverse conditions.

but’s it’s hard to ignore how the Type A Personality areas of europe coincide with the hajnal line. at least, i find it hard to ignore. what happened behind the hajnal line?

at the risk of repeating myself (is there an echo in here?), what happened behind the hajnal line starting in the early medieval period was:

- changes in mating patterns (thanks to the church) from close relative marriage to more distant marriages, thus breaking down clans and tribes
- changes in the economic structure from whatever the h*ll went before (i have no idea) to manorialism
- changes in family structures (thanks to both the increased outbreeding and manorialism) from extended families to smaller nuclear or stem families

all of these would’ve changed the selection pressures on the populations in the areas where these practices were adopted.

inbreeding and outbreeding probably select differently for genes related to altruism, so all of the outbreeding behind the hajnal line likely selected for different sorts of altruistic behaviors than those seen in other populations — strong societial collectivistic feelings, for instance. (perhaps it looks something like this.) the changes in family structures likely also selected for different traits — for one thing, different family types have different family dynamics and some personality types likely do better in some types of families than in others.

but what’s manorialism got to do with it? like i said here…

“you have this manor system in which the lord (or monks) of the manor let out land to farmers to run (they then owed the manor service or rent). the lord of the manor specifically let out land to married couples, ’cause it took two to run a small farm properly, i.e. to carry out all the necessary duties…. so who is a young and upcoming, hard-working, driven farmer going to seek out to marry? well, maybe he just marries the prettiest girl he can find — but maybe, if he’s smart, he marries someone like himself who is also hard-working and driven and wants to run a successful manor holding. they might even be attracted to one another. maybe it was exactly those sorts of couples — the smart, hard-working, industrious couples — who were the most successful and left the most descendants behind.“

…so maybe manorialism contributed to higher average iqs and traits like “strong drive to succeed.”

where did manorialism occur? it started with the franks as early as the seventh century in their territory between the seine and the rhine. it was a characteristic feature of the carolingian empire and was pretty much present throughout carolingian territories.

it was introduced to northern, but not southern, italy by the carolingians. southern italy was part of the byzantine empire so manorialism wasn’t introduced there in the early medieval period, nor was it adpoted there later in the middle ages. manorialsm never took hold in greece or the balkans.

manorialism was present in england by the eighth century, but not scotland or ireland or wales. the normans brought it to ireland in the eleventh century, but its adoption was patchy at best. southern spain did not experience manorialism due to moorish rule, but parts of northern spain did.

manorialism spread eastwards during the ostsiedlung and was really the fundamental economic structure of the german settlements to the east. the system was also introduced, as late as the sixteenth century, to eastern regions of europe like poland and belarus. the eastern edge of the hajnal line — where the western and eastern churches meet — represents the limits of the manor system in europe.

the populations behind the hajnal line have a unique history (well, all populations do!) and, i think, were very much shaped in a human biodiversity sort-of way during the medieval period. there were strong selection pressures precisely in areas related to mating and reproduction that really profoundly changed northwestern/central europeans and laid the foundations for all sorts of interesting things that happened in europe. it may have also laid the foundations for our demise, but hey — you can’t have everything.

none of the populations in the periphery in europe experienced this collection of changes. they may have experienced some of the changes — like the ban on cousin marriage out to second cousins in greece and eastern europe — but because they didn’t have the manor system, they did not develop nuclear families or highly mobile individuals like the core of europe. and some populations, like the southern italians and the irish, in addition to not adopting the manor system, also just kept right on inbreeding up until very recently.

here are some excerpts from michael mitterauer’s “Why Europe?: The Medieval Origins of Its Special Path” from which i learned everything i know about manorialism [pgs. 53-57]:

“These cross-cultural examples of analogous, and markedly contrasting, agricultural systems illustrate the uniqueness of the manorial and the hide systems as they developed as components of the early medieval agrarian revolution in the Frankish heartland. The diffusion of innovations from the agrarian economy and the agrarian system very often took place in concert — as, for instance, during the great process of the colonization of the East. This was not true in every case, of course. The manorial system expanded southward, following the Frankish Empire’s specific forms of lordship and penetrating into regions where typical features of the Frankish agrarian revolution did not exist. A large, relatively homogenous area was created by these expansionist movements, which were characterized on the whole by identical or similar structures of the agrarian system and the social order it generated. Over against this ‘core Europe’ was a ‘peripheral Europe’ that did not acquire these structures until a relatively later date — or not at all. Here we can list Ireland, Wales, and Scotland in the West; the area of eastern Europe beyond the Trieste-St. Petersburg line that was unaffected by the colonization of the East; the entire Balkan region; southern Italy, which was formerly Byzantine, along with the southern part of the Iberian Peninsula that was under Moorish rule for so long a time. The political, economic, and social evolution of many regions in ‘peripheral Europe’ took a different turn because of their clinging to other, traditional agrarian systems.

“As Frankish models of the manorial system advanced through various parts of Europe, they met with quite diverse forms of social organization. In the North and East it was mainly tribal societies that were transformed by the new structures of the agrarian reovlution. They could be organized in very different ways, as was evident in medieval Europe. When Germanic tribes settled on Roman imperial land — the Franks, Burgundii, Alemanni, and Bavarii among them — categories of descent as a basis for social order played a role, a role very different from the one it played in the thinking of Celtic tribes in Ireland or of Finnish and Baltic tribes around the Baltic Sea. Consequently, the resistance of the various tribes to manorial structures was highly differentiated from region to region. In many places these structures rapidly superseded more ancient types of tribal organization; in many others, not at all. We can say that the manorial system and the tribal system were basically incompatible at the social level of the peasantry. The economic rationale for an agriculture based on manorialism cannot be harmonized with dominant organizing principles based on kinship. That proved to be the case throughout Europe wherever the social organization of the manorial and hide system supplanted tribal structures. In many non-European empires, the lack of such organizations might well have contributed to the local preservation of social forms based on descent in spite of strong influence of a central state — for instance, in China and the Islamic world….

“The manorial system of the Carolingian Empire was premised on the personal relationship of the lord with his familia [all of the people who lived and worked on the manor, most of whom were not related to one another]. This principle continued to have a more or less potent effect on every form of the manorial system that grew out of it. Any and all lordship in this tradition was lordship over a group of people organized ‘as a family….’

“Manorialism and the hide system were just as significant for European social history on the macro level of organized lordship as they were on the micro level of household organization. Claude Levi-Strauss has coined the term societe a maison, which fits these developments in European society like a glove. Households seem to have been a central ordering principle in this case. In a peasant society, at any rate, the primary social orientation was to one’s house, not to one’s relatives. This was an essential distinguishing feature vis-a-vis societies oriented toward descent; these kinship patterns were located around the periphery of Europe, but in the main they lay beyond Europe’s borders. Belonging to a household was clearly a basic building block of the bipartite estate in the Frankish Empire. On the one hand, there was the villa, the lord’s manor, or the steward’s manor, with its resident labor force, the members of which were not tied to one another by kinship; on the other hand, there were the farms of the servi casati, that is, of the unfree laborers and their dwellings, as well as the coloni who were boind to the soil and therefore to a house. Together they formed the familia, an overarching household embracing several households…. Affiliation with a farmstead of this kind was socially determinative, not the affiliation to a group through kinship.“

update: see also jayman’s IQ Ceilings?

previously: medieval manoralism and genetic relatedness and family types and the evolution of behavioral traits and assortative mating and the selection for high iq in (some) medieval european populations?

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