random notes: 02/14/13

cousin marriage rates for german jews living in the prussian province of hohenzollern between ca. 1875-1920 (117 marriages):

– first cousin marriages = 16.2% ± 3.4%
– consanguineous marriage up to and including second cousins = 19.6% ± 3.7%

source [pdf]. original source: Reutlinger, W. 1922. Über die Häufigkeit der Verwandtenehen bei den Juden in Hohenzollern, und über Untersuchungen bei Deszendenten aus jüdischen Verwandtenehen. Arch. Rassenb. 14: 301-305.

a little more on these rates from In Search of Jewish Community: Jewish Identities in Germany and Austria 1918-1933 [pgs. 234 and 241]:

“On the other hand, there is considerable evidence to back up the impression that village Jews were marrying cousins and other close relatives in increasingly large numbers.[44] …

“[44] In Hohenzollern, there was an 11 percent rate of marriage to relatives (5 percent to first cousins) among Jewish couples who died before 1922; of those still alive in 1922, the rate had increased to 22 percent (16 percent to first cousins. These rates were several times as high as the rates for Christian marriages. See Wilhelm Reutlinger, ‘Uber die Haufligkeit der Verwandtenehen bei Juden in Hohenzollern und uber Untersuchungen bei Deszendenten aus judischen Verwandtenehene,’ Archiv fur Rassen- un Gesellschaftsbiologie 14 (1922): 301-303, quoted by Marion Kaplan The Making of the Jewish Middle Class: Women, Family, and Identity in Imperial Germany (New York, 1991), p. 273 note 206. See also Cahnman, ‘Village and Small-Town Jews,’ pp. 122-23, for an impressionistic discussion of the same phenomenon.”

so, the rates of consanguineous marriages increased for jews in hohenzollern over the period from 1875-1920. that pretty much mirrors the general trend of increasing cousin marriage rates right across europe at the time, only the actual rates for the hohenzollern jews were much higher than for most europeans — well, at least most germans.

this 11% consanguineous rate (5% to first cousins) for jewish couples who died before 1922 is a lot higher than the only other definite rate i have for european jews which is from alsace-lorraine in 1872-76 (so i’m thinking these might be kinda contemporaneous rates) — and that rate was 2.3% (consanguineous marriages).

see also: jewish mating patterns in nineteenth century russia.

a bizarre story on a case of cousin marriage and inbreeding depression from china that … well, i’ll just let you read it for yourselves. from A Family That Climbed Out of Inbreeding Depression [pg. 1064]:

“In 2008, a family was fortuitously found in Northeast China. Before the 1948 Revolution, this family was wealthy and owned vast amount of land. After nationalization, the family was given a tiny house with a small plot of land. Subsequently, during the Cultural Revolution (1966-1976), all landowning families in the country were severely prosecuted and socially ostracized. The social stigma on the members of former land owning families was so persuasive that any form of association with them was deemed as dangerous. At that time, there were two children of marriageable age. As their parents were unable to find unrelated mates from the society, they arranged an intra-family marriage between available first cousins. The union produced five offspring: three mentally retarded girls, one deaf-mute girl, and one mentally retarded boy who did not survive (Figure 1). The consanguineous (first cousin) parents supported their four disabled daughters throughout their childhood. By the time these daughters were of marriageable age, the Cultural Revolution in China was over and the social stigma of land-owning families was lifted. Thus, the consanguineous parents were able to arrange marriages of their four unfit daughters with four biologically unrelated men. The deaf and mute girl was married to a deaf and mute man from the same village. The three mentally retarded daughters were married to healthy men, of low socioeconomic status, and they resided in their husbands’ homes in the same village. The most severely retarded daughter was married to a poor man who came to their family looking for food; he was offered this daughter and accommodation within the family household. After marriages of their daughters, the consanguineous parents continued to support all four families, and each of the four daughters produced one healthy child (maximally allowed number of children in China at the time). The most severely retarded daughter accidentally lost one child at birth. Today, the consanguineous couple has four grandchildren who are attending regular school and are expected to marry to biologically unrelated mates….”

could the cultural revolution have encouraged cousin marriages during the time period in china? at least in some sectors? weird.

weregilds. did you know that weregild payments were made directly from one clan/kindred member to his corresponding clan/kindred member in the other clan/kindred (whichever was the aggrieved clan)? i didn’t.

i always imagined that all the weregild payments were sorta pooled together and passed from one clan to the other, but no … the father in one clan paid directly the father in the other clan, the father’s brother in one clan paid directly the father’s brother in the other clan, and so on and so forth. at least that’s how it was done in iceland … at least according to phillpotts [pg. 13]:

“Each class pays to the corresponding class of the opposite side, thus the father, son and brother of the slayer pay to the corresponding kinsmen of the slain. It is to be observed that the slayer pays nothing, the assumption being that he was exiled and his goods forfeited.”


i mentioned over here that edmund i (922–946) seems to have been one of the first anglo-saxon/english kings to have really tried to put an end to the traditional blood feuds in england (which were tied to the weregild payments — see above — if the weregild wasn’t paid when someone was slain, the aggrieved clan/kindred had the right to exact revenge on the slayer’s clan/kindred). re. one of his law codes (from phillpotts – pgs. 218-19):

Eadmund’s secular laws mark a notable advance in one respect: private warfare between families, as a result of a slaying, is to be stamped out, and the slayer alone is to bear the feud, if feud there is to be.

“II. 1. ‘If henceforth anyone kills any man, let him himself bear the feud, unless with the help of friends he pays full wergild within 12 months, whatever the birth (of the slain man,’ i.e. however high the wergild be).

“It must be remembered that a slayer is not involved in a feud unless he cannot or will not pay wergild; and if he can pay wergild there is no feud. So here we must assume that the slayer has not been able to produce the sum out of his own pocket, and that his kinsmen have been unable or unwilling to help him. That even this secondary liability of the kinsmen is purely voluntary is seen from the next clause:

“1. ‘If the *mægð* [kindred/extended family] forsakes him, and will not pay for him, then I will, that all the *mægð* be without feud, save the actual delinquent, if they give him thereafter neither food nor protection.

“2. ‘If however thereafter any one of his kinsmen shelter him, then let him be liable to the king for all that he possesses, and bear the feud with the *mægð* (of the slain), for they (the kinsmen) had before forsaken the slayer.

“3. ‘If however one of the other *mægð* takes vengeance on any other man than the actual delinquent, let him be outlaw to the king and to all his (the king’s) friends, and lose all that he possesses.'”

so edmund is the earliest example i know of in england of the state trying to position itself in between all of the homicidal lunatics in order to put an end to the violence. he (or the crown, i suppose) would pay the weregild if a clan/kindred wouldn’t in order to stop a blood feud from erupting.

edmund didn’t live very long though — he died (heh) in a fight when he was just 26 — so i don’t know how well-enforced his edict ever was.

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italy – reversal of fortune?

who knows?

but italy could be another place to look for a possible rapid inbreeding drop-off/rapid iq increase connection (see yesterday’s post) just ’cause the consang data are available. and they did, indeed, have a pretty rapid decrease in cousin marriage rates — at least in northern italy — not so much in the south. (i can’t think of any other examples where consang data are readily available — i mean without delving into church records or something like that.)

no idea if there are any early iq data available for italy, though. i won’t be looking for them (iq questions? – meh) — just wanted to let anyone who might be interested know that the numbers for the drop in inbreeding do exist for italy. (^_^)

look for the consang data here: Consanguinity, Inbreeding and Genetic Drift in Italy (tables also available here).

i put together a table of the first and last lustra in cavalli-sforza’s data set for a previous post, but there are data for each lustrum in between, too. you can get an idea of the scale of the drop-off (in the regions where there was a drop-off) from my nifty table:

1st cousin marriages - cavalli-sforza

previously: japan – reversal of fortune?

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consanguinity and polygamy

sean suggests that there is a correlation between consanguintiy and polygamy (or, rather, polygamy and consanguinity). i don’t know if anyone’s ever looked for a correlation between the two. if they have, i haven’t seen it. what someone should do is take the populations from consang.net (not the nations but the populations) and see if there is any correlation between consanguinity and polygamy or not. i’ve put that task on my “to do” list, but i can’t promise that i’ll get to it any time soon.

what i have done is check murdock‘s ethnographic atlas to see what sorts of societies (monogamous, occasionally polygamous, or polygamous) are also consanguineous (here consanguineous means first or second cousin marriage — i haven’t included uncle-niece marriages as that info is not available in the murdock atlas).

the cross tabs i used were DOMESTIC ORGANIZATION and NUMBER OF COUSIN MARRIAGES [Allowed]. the results are sorted into the following rows…

– Missing Data
– Indep. Nuclear Family – Monogamous
– Indep. Nuclear Family – Occasional polygyny
– Indep. Polyandrous Families
– Polygynous – Unusual Co-wives Pattern
– Polygynous – Usual Co-wives Pattern
– Minimal (stem) extended families
– Small extended families
– Large extended families

…and columns…

– Missing Data
– All four cousins
– Three of four cousins
– Two of four cousins
– One of four cousins
– No first cousins
– 1st & some 2nd cousins
– No 1st – 2nd unknown
– No 1st or 2nd cousins

i skipped the two “Missing Data” groups (fourteen results). i also skipped the “No 1st – 2nd uknown” group (twenty-seven results) since the presence or absence of second-cousin marriage was unknown. left out the polyandrous groups (all three of them), too. and i also drilled down (manually!) in the extended family categories (minimal/stem, small extended, and large extended) to check for consanguinity and polygamy there ’cause i couldn’t figure out how work that into the table (you’re welcome). i then combined all the monogamous, occasionally polygamous, and polygamous groups together (n=142 in total).

what did i find?:

consanguinity and polygamy 02

well, for one thing, there’s a lot more polygamy and occasional polygamy out there in the world than monogamy, but then we all knew that already, didn’t we? there’s also more consanguineous marriage practices out there than not — or, at least, they’re allowed in more societies than not — but we’re all starting to know that now, too, aren’t we? (^_^) even in monogamous societies, there are twice as many that allow some form of cousin marriage (first or second) than those that don’t allow any.

the rate of consanguineous to non-consanguineous marriage allowed in monogamous societies is about 2:1. in polygamous and occasionally polygamous societies it’s about 2.5:1. so, yeah — there are more consanguineous marriages permitted in polygamous societies than monogamous ones, but is the correlation between the two (consanguinity and polygamy) very strong? i dunno. doesn’t really seem like it, but you tell me.

in Ya̧nomamö, chagnon suggests that groups that practice polygamy marry their cousins with greater frequency partly because the individuals in those societies have more cousins. he gives as example two ya̧nomamö extended families, one that had a founder with more wives than the other. because he founded so many lineages, as it were, the descendants of the guy with more wives were able to more easily find a cousin to marry simply because more persons who were their cousins existed. don’t know if this holds true for other polygamous groups, but it’s an interesting idea.

here are the numbers for you:

consanguinity and polygamy 03

consanguinity and polygamy 04

btw, the monogamous groups which allow(ed) cousin marriage are:

– the inca
– the badjau (pacific region)
– the burmese
– the romans
– the bribri (south america)
– the chinese (in chekiang)
– the tuareg
– the copper eskimo
– the lapps
– the iban (pacific region)
– the japanese (southern okayama)
– in the punjab (west)
– the vedda
– the yapese (pacific region)
– the manchu (aigun district)
– the kaska (north america)
– the toradja (pacific region)

(note: comments do not require an email. some toradja folks.)

consanguinity and homicide

luke says/asks:

“It is interesting to compare world maps of consanguinity and murder rates…. Incidentally, someone who is proficient in computing correlation coefficients could use the country tables in the two links above to compute an actual number.”

here at hbd chick, we take reader requests! (^_^)

so i plotted the consang.net data as compiled by woodley & bell — just to be consistent — against the intentional homicide rates as compiled by the united nations office on drugs and crime and got … *drumroll please!* …

…nuthin’. zip. zilch. nada. a correlation of -0.0758. in other words, there is noooo correlation between modern consangunity rates and known intentional homicide rates. i love non-result results! they’re some of the best. (^_^)

here’s a chart for you — x-axis=consanguinity rates, y-axis=intentional homicide rates (as bob would say: that’s a scatter plot!):

consanguinity and intentional homicide - scatter plot

and here’s a table of the data sorted by homicide rates:

consanguinity and intentional homicide

like i said, though, i think there are problems with using the modern consanguinity rates when we are (i think probably/possibly) talking about the evolution of behaviors — and steven pinker thinks that there are probably some problems with the collection of homicide rates in certain countries. still — no correlation is no correlation.

previously: consanguinity and democracy

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consanguinity and entitlement

the following prolly doesn’t mean much ’cause, for one thing, the sample size is prolly too small (26 countries) — just think of it as me goofin’ around. (^_^)

however, for your mid-week pleasure, here is the 0.49 correlation (such as is it — see short but sweet intro above) between consanguinity (means taken from hoben, et. al.) and percentage of those who think democratic governments definitely ought to tax the rich to subsidize the poor (% responding “10”):

and here’s a nice picture. x-axis=mean consanguinity rates. y-axis=percent responding *10* to this question. (click on chart for LARGER view.)

previously: a sense of entitlement and a sense of entitlement ii

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pathogens and consanguinity and democracy

so at long last, the final point from the woodley & bell paper that i want to draw attention to (there are lots more neat points in the paper that you can read for yourself here): pathogens and consanguinity and democracy.

yesterday’s post was about how there seems to be some sort of a connection between the frequencies of pathogens in any given environment and consanguineous matings. it’s not the strongest of connections, but it seems to be there (i’m convinced anyway).

woodley & bell found that pathogen load does, indeed, have an impact on how (liberally) democratic societies are or not — but via consanguinity. there is a correlation between pathogen load and presence/absence/degree of democracy, but it’s not a direct one. here are their path analyses from their paper (more details in previous post). follow the arrows:

so it’s: pathogen load -> consanguinity -> democracy (or not).

i’d amend that a bit and say it’s: pathogen load + other social/economic factors -> consanguinity -> democracy (or not).

if i were to amend it even further in a theorizing sort-of way (that’s theorize with a small “t” not a big one), i’d say it’s:

pathogen load + other social/economic factors -> long-term consanguinity/endogamous matings -> democracy (or not) and/or a whole lot of other neat things like individualism and low levels of corruption and nepotism and so on and so forth.

that is all! (^_^)

previously: consanguinity and democracy and consanguinity and islam and democracy

(note: comments do not require an email. how to reduce pathogen load in the population.)

pathogens and consanguinity

remember the woodley & bell paper about the connections between consanguineous matings and democracy (or lack of) that i said i was going to post a lot about? and then i got distracted? well, let’s get back to it.

by way of introducing woodley & bell’s idea that pathogens (and consanguinity) and democracy don’t go together, the last post in this thread of posts had to do with possible connections between pathogens and individualistic vs. collectivistic societies — i.e. seems like the more pathogens in your environment, the more collectivistic (ethnocentric, conforming, suspicious of outsiders) your society is going to be. now i want to look at one more paper before i get back to consangunity and democracy.

in On the Adaptive Origins and Maladaptive Consequences of Human Inbreeding: Parasite Prevalence, Immune Functioning, and Consanguineous Marriage [opens pdf], hoben, et al., present their finding of a correlation between frequencies of pathogens and frequencies consanguineous marriages in various societies around the world. it’s not a huge correlation — r = 0.39 — but it is there. the more pathogens you’ve got in your environment, the more likely you are to practice cousin marriage. kinda/sorta.

like the paper in the last post, these researchers worked from the consang.net data and the historic pathogen data from this paper. hoben, et al., didn’t include any nifty charts in their paper, and since i like my data served up visually, i made a chart of my own (click on image for LARGER view):

x-axis=their pathogen index. positive numbers (z-scores) indicate higher frequencies of pathogens; negative numbers, lower frequencies. bosnia-herzegovina has a z-score of 0; england has a z-score of -1.01. burkina faso has the highest z-score at 1.16. canada has the lowest z-score at -1.31.

y-axis=weighted mean consanguineous marriage rates.

i think there is a broad, general pattern here. and it makes some sense. as the authors say:

“[I]ncreased homozygosity and other genetic coadaptation that results from inbreeding can facilitate highly specific forms of immunological resistance to local parasites, and … these immunological benefits will be most pronounced under ecological circumstances in which endemic pathogens are more highly prevalent (Denic et al., 2008; Denic and Nicholls, 2007; Fincher and Thornhill, 2008a, b; Shields, 1982)…. [O]ur study indicates that, under certain circumstances (i.e., high pathogen prevalence), inbreeding may have advantages that outweigh its costs.”

but the correlation was not that high. and i think part of the reason for that is “technical” — that is that there are some “glitches” in the consang.net data that the researchers didn’t take into account.

take brazil, for instance. high on the pathogen index (0.930) but pretty low consanguinity-wise (4.348%). but that’s because brazil was fairly recently settled by westerners (and blacks and japanese) who brought roman catholic traditions with them when they settled there — in other words, cousin marriage prohibitions. so of course the consanguinity and pathogen frequencies don’t match very well for brazil. what should be looked at are native brazilian consanguinity rates which are more like 13% (only one study, unfortunately — see page 3** [opens pdf]).

the authors have also calculated the consanguinity data for slovakia as 11.618%, but that includes gypsies [pg. 10 – opens pdf] who are consanguineous wherever they go, so that is undoubtedly skewing the numbers for slovakia. the consanguinity figures for czechoslovakia are more like 0.2% [pg. 1 – opens pdf].

the BIG outliers, though, are the arabs and all their middle eastern/north african/south asian muslim buddies. they are the ones throwing off the correlation completely. i’m talking about most of the dots that are right in the middle of the chart: 0.5000 or lower on the pathogen index (so, not a lot of pathogens) but above the 20% consanguinity rate:

regionconsang. ratepathogen index
uae – 36% – -0.450
kuwait – 51.7% – -0.340
iran – 32.2% – -0.150
oman – 35.9% – -0.140
pakistan – 51% – 0.020
saudi arabia – 38.4% – 0.040
libya – 37.6% – 0.040
jordan – 31.2% – 0.160
afghanistan – 55.4% – 0.230
syria – 31.6% – 0.300
lebanon – 26.6% – 0.360
yemen – 35% – 0.410
egypt – 31% – 0.440

these societies are amongst those that have the highest consanguinity rates, and yet some of their pathogen index scores are very low. the united arab emirates, for instance, scores like france (-0.460) or the republic of ireland (-0.450). qatar has got the exact same score as australia (-0.250). and saudi arabia and pakistan have lower scores than italy (0.160).

clearly having pathogens in the environment is not the whole story when it comes to the push towards cousin marriage. and hoben, et al., don’t claim that either:

“To complement those partial explanations [economic, etc.] for the persistence of consanguineous marriages, in the present research we offer an additional explanation that we label the ‘parasite hypothesis of inbreeding.'”

a complementary explanation. i agree! prolly the most fundamental, underlying one i would guess.

previously: consanguinity and democracy and consanguinity and islam and democracy and pathogens and culture

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more on consanguinity in england (and scotland)

below is a chart summarizing the findings from various consanguinity studies for england (and a couple for scotland). i’ve adapted catherine linley day’s chart which appears in her thesis [opens pdf] on pg. 245 (basically, i’ve added her findings, fleshed out darwin’s findings, and added a couple of others — i also divided the findings between north and south). most of these studies have drawbacks and lynley day goes through them all in detail on pages 245-250. click on image for LARGER view:

as you can see, and as i mentioned yesterday, the overall pattern seems to be that people in southern great britain have largely avoided cousin marriage since the 1500s (possibly as far back as the 1300s), while the people further north, not so much. if anything, cousin marriage increased in the succeeding centuries, particularly in the nineteenth (a general pattern for much of europe).

the sorts of cousin marriage rates we see for the english from the medieval period to the modern — ranging from 0.00 to 5.30 — are just not even in the same ballpark cricket pitch as other parts of the world like the arab peninsula or even southern europe. and they haven’t been. for centuries. the english, especially members of the southern subspecies, have apparently avoided cousin marriage like the plague.

there are gaps, i know. big gaps. more numbers would be nice, of course. further research is required. (~_^)

let me go through the list.

the first entry for fourteenth century ely. i posted about that here. fifty percent (50%) of all marriages in ely, cambridgeshire, in the 1300s were to people living outside of ely. hard to know if this means people were avoiding cousin marriage or not — people from ely could’ve been marrying their cousins living in other villages — but it’s likely, i think, that this means they were avoiding marrying close family members. at this point in time, the roman catholic church had banned cousin marriage up to and including third cousins, and as lynley day points out with regard to the second entry on the list (1500s england), for whatever reasons, medieval english people seemed to take these restrictions seriously [pg. 246]:

“Marriage dispensations from the reign of Henry VIII were used to estimate consanguinity (Smith et al. 1993). The results produced from these documents were surprisingly low (Table 6-4), with a total absence of 1st cousin marriages and a very low level of 2nd cousin marriages, even compared to modern studies. One possible explanation, as noted by Smith and his colleagues, is that the marriage dispensations may not reflect actual practice, although anecdotal evidence suggests that there was a real aversion to close consanguineous marriage in the mediaeval period (Smith et al. 1993). Another explanation proffered is that marriage dispensations were almost exclusively the preserve of the rich, and that the poor and labourers did not avail themselves of the system (Smith et al. 1993).”

the third item on the list is lynley day’s study which i posted about yesterday. the next is bramwell’s study for shropshire. bramwell used george darwin’s techniques to calculate cousin marriage rates in that county by looking at surnames. his results are not far off lynley day’s and so, i’d guess, are probably fairly accurate. the same can be said for darwin’s results (which i posted about here).

pearson’s hospital study involved checking for consanguinity between the parents of sick children. while consanguineous couples might have more sickly children on average compared to the rest of the population, pearson’s finding of 1.3% first cousin marriages for londoners of the time also seems to fit well with the other findings. he attempted to double-check his results by surveying the readers of the british medical journal (bmj), but he may have gotten a skewed response (only persons married to cousins responding) and/or many of the readers at the time may have been from the upper classes. one or both of those may account for the high (for england) 4.69% first-cousin marriage rate that he found.

the next study, bell’s study of hospital patients across england, had the same methodology as pearson’s, but found a slightly lower consanguinity rate. but the late nineteenth century/early twentieth century (when the study was conducted) is just the point when consanguinity rates started to drop across europe after peaking between 1875-1915, so that may account for the lower rates.

smith’s study of the records of the society of genealogy members probably has a slight bias towards middle-/upper-class folks who, as g. darwin showed, tend to have slightly higher consanguinity rates in england (and elsewhere, too, i think). finally, the study of consanguinity rates in twentieth century reading by coleman can be found here.

previously: consanguinity in england – north vs. south and but what about the english? and cousin marriage rates amongst nineteenth century english and english jews and exogamous marriage in medieval england and invention of the modern world

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