hejazis vs. najdis (and vice versa)

in my last post on saudi arabs, i mentioned that there are maybe, perhaps some hints that the historic mating patterns amongst the najdis of the central part of the arab peninsula were closer than those amongst the hejazis of the western coast. maybe. there are only hints, so it’s hard to be sure.

one other hint that the hejazis maybe outbred a bit more than the najdis is the somewhat greater freedoms that women have historically had in the region (the pattern seems to be the stronger the inbreeding, the more restrictions on women). from Cradle of Islam: The Hijaz and the Quest for an Arabian Identity [pg. 27]:

“As in other societies the Arab concept of family is closely linked to that of female honour. In the Arabian Peninsula the urban Hijazis have historically been viewed as more lax or lenient in such matters than tribal Najdi culture, with its strict Wahhabi norms of sexual segregation. An increased emphasis on female honour has, however, developed among some of the Hijazi *’awa’il* in reaction to Najdi standards.”

if the elevation/marginal environment theory of inbreeding/outbreeding is correct, then it would make sense if arabs living right along the coast in the west were inbred less. same for those on the east coast, i suppose. (the greatest oubreeders of the arab peninsula ought to be in the southeast area of saudi arabia, but i don’t think many people live there!):

saudi arabia - topography

in any case, saudi society is not just clannish, it’s downright tribalistic — and the people of the hejazi region don’t like the people of the najdi region. and the feeling is very much mutual [pgs. 16-17, 85]:

The most obvious and important expression of the persistence of social boundaries is the rarity of intermarriage between Najdis and Hijazis, with obvious implications for cultural assimilation. Hijazi opinion on this matter varies. Some explain that Najdi men fear the consequences of marital alliances with Hijazi families, while others contend that Hijazis are reluctant to allow their daughters to marry Najdis, because of polygamy, ease of divorce and stricter gender segregation among the Najdis. Najdi men — who do not hesitate to take wives from other Arab countries — regard marrying a woman from the same country as a greater commitment, especially when she is from an inferior or less ‘pure’ lineage in the Najdi grading of tribal descent. Meanwhile, the Hijazies, who claim descent from the Prophet’s tribe, the Quarysh, consider themselves the superior ones. Competition in ‘purity of blood’ in the Arabian Peninsula reaches its apotheosis in the context of intermarriage, and the few instances of it are typically between a Hijazi man and a non-tribal (i.e. ‘non-pure blood’) Najdi *khadiri*, as a tribal Najdi *gabili* will not marry outside the group. Even in these rare cases, the Najdi *khadiri* family typically makes the marriage procedures very lenthy and costly….

“The images that Hijazi and Najdi have of one another and the names they use to describe each other are further indications of social boundaries and the consciousness that sustains them. The Hijazis, for example, call the Najdis *shurug* (Easterners), a derogatory term. Another term, *badu* (Bedouin), carries an even worse connotation — essentially a lack of urban refinement. On the other hand, the Najdis call Hijazis *tarsh al-bahr*, (the flotsam of the sea) and *bagaya hujjaj*, (pilgrimage remnants). Whereas the first term is applied to those from Jeddah and the second to Meccans and Medinese, both allude to the ‘impurity’ of Hijazis’ Arab descent, owing to intermarriage with non-Arab Muslims. While the Najdis pride themselves on their lineage and *asala* (purity of blood), the Hijazis pride themselves on their *zawg* (good taste), *anaga* (elegance), *nazaka* (refinement) and *usul* (knowledge of the rules of propriety). To be sure, Hijazis also place lineage as the first criterion of status and respectability, especially those claiming descent from the Quraysh. But for those from other Muslim countries who settled in Mecca, Medina or Taif, lineage does not imply ‘blood purity’, but rather three generations of good social standing. As a result, ‘Najdis regard Hijazis as degenerate and not quite Arabian’….

“Marriages between Hijazis and Najdis are very rare. The exceptions are one way, occurring between a *khadiri* (non-tribal, ‘non-pure’ Najdi) woman and a Hijazi man, especially if he is wealthy and offering a high *mahr*. Najdis do not marry Hijazis because their lineage is not considered pure enough. Therefore Hijazis are excluded from marriage with the Najdi elite…. The rarity of cases of inter-marriage between Hijazis and Najdis is the most significant expression of the social boundaries between the regions of Saudi Arabia and an obvious example of the cultural distinctivenss of the Hijazis. Despite the attempt at integration and national homogeneity, marriage practices and alliances demonstrate the fractured nature of the Saudi state.

not much love there, then.

and, like i said, saudi society is very tribal — extremely tribal. from Challenges to the Cohesion of the Arab State [pgs. 181-182, 184, 186-187 – links added by me]:

“Saudi Arabia is known in the literature as a ‘rentier state.’ In its most narrow meaning, a rentier states refers to a state which gains most of its revenues not from taxes, but rather from the income (‘rents’) derived from the sale of natural resources, in this case — petroleum. In the Saudi case, the state distributes much of the income to the population, without taxing it. Saudi Arabia has (as have other wealthy Gulf states) an unwritten ‘social contract’ between the Sa’ud family and its subjects: the family runs a cradle-to-grave social welfare system and guarantees employment in the public sector; in exchange, the population is expected to be loyal, without having a representative system. It is, in fact, a system of ‘no taxation, no representation.’

This governmental system dovetails quite nicely with the tribalistic character of Saudi Arabia, and to a great extent even duplicates it. Although the tribe, as a discrete social unit, has been somewhat weakened in Saudi Arabia due to the efforts of the Saudi state, the structure of relations between the Sa’ud family and the population operates to a great extent according to tribalistic patterns and values, and thus contributes to national cohesion.

“Certain political, and socio-economic groups develop a corporate identity and behavior, not unlike that of tribes. These groups are termed *’asabiyyat* (from the word *’asabiyya*, tribal solidarity), and indeed form the core of social cohesion in Saudi Arabia. They are patron-client groups that have a common tribal, regional, family, or ethnic background, which is used to obtain jobs or resources from the central government. In return, the central government uses these relationships to command the loyalty of these groups. In this sense, the state is an extension of tribal politics.

in 1961, when the saudi central government was moved from jeddah (in hejazi territory) to riyadh (in najdi territory), pretty much ALL of the hejazi civil servants were sacked and replaced with najdis [pg. 94]. now THAT’S what i call nepotism!

more from Challenges to the Cohesion of the Arab State:

“Tribalistic patterns of behavior are characterized by a high degree of personalization since they are based on personal relationships. For instance, the main ministries are headed by members of the Saudi royal family that represent the various ‘circles of power.’ To get a job in one of those ministries, one must ally oneself with the relevant faction of the family, or with someone associated with it. The most powerful circles of power [in 2008 when this book was published-h.chick] are the Al Salman (connected to Salman, the governor of Riyadh province), the Al’ Abdallah (associated with the present king), the Al Fahd (connected to Fahd, who was king until his death in 2005), the Al Na’if (connected to the minister of the interior, and the Al Sultan (connected to the heir apparent and minister of defense and aviation). These circles act as corporate groups looking out for one another. They consist of blood relatives and their associates. Until a few years ago, applicants for government jobs were required to provide their family and tribal background, going back five generations, as part of the application process. This clearly illustrates how the royal family uses tribal patterns and values to maintain its rule.

“Like the head of a tribe, the state is responsbile for the protection of its citizens. The state, personified in the Sa’ud family which functions as the head of a tribe, protects the people’s physical and financial safety. Like all tribal leaders, members of the royal family mediate disputes, and keep the peace….

The Saudi royal family/state also functions as a genealogical organizer of society. As tribes did in the past, it determines who will marry whom. The fact that it makes it hard for Saudis to marry non-Saudis contributes to the myth of an entire country under Sa’ud domination, of one vast exclusive tribal family patronized by the Al Sa’ud. Since Saudi citizenship, which grants admission to the tribal family, confers entitlement to the largesse of the *shaykh*, the Saudis have created powerful incentives for their citizens to accept the truth of the myth of Saudi national identity, an identity fused with religion, in which membership is in fact a coveted privilege bestowed by birthright….

“Regional identities

“The region with the most highly developed sense of regional identity is the Hijaz, a strip of land along Saudi Arabia’s Red Sea coast, stretching from the border with Jordan in the north nearly to Yemen in the south. In it are situated the two holiest places in Islam, Mecca and Medina.

“In the Hijaz the elite are quite aware of the status they enjoyed before what the Saudis call unification, and some Hijazis call occupation, or annexation. When they feel they are being treated as second-class citizens, which they often are because the Najdis hold most of the government and religious jobs, they strive to gain recognition by asserting their distinctiveness as the elite of Islam’s holiest places.

“One recent manifestation of the this regionalism is the periodical *al-Hijaz*, published in London by the Hijazi National Organization (*al-jam’iyya al-wataniyya al-Hijaziyya*). The periodical is extremely anti-Saudi, and seeks to celebrate Hijazi culture and distinctiveness. The articles, most of which remain unsigned, refer not to the ‘unification’ of Arabia under the Saudis, as stated in the official narrative, but rather to the occupation of the Hijaz….

“Some Hijazis are thus beginning to assert their distinctiveness, whether through writing about Hijazi customs and food, or by wearing Hijazi dress. Indeed, there seems to be a revival of Hijazi dress lately. People who choose to wear Hijazi dress do so at some risk since it is Najdi dress which is considered the national dress and is worn by most of those in or close to power. What one wears is a statement, and is noted immediately. Some Hijazis are demonstratively reverting to their own regional dress, which includes a tighter-fitting robe calle a *jubba*, and a turban, or *’amama*….

“One man stands out as leader of the Hijazi cultural movement, namely Sami al-Angawi, an architect, who has made it his life’s work to preserve the customs, dress, and architecture of the Hijaz against Najdi attempts to eliminate them. He openly wears Hijazi dress. Moreover, he explicitly declares that he is a Sufi, a mystic — in other words, that he belongs to a stream of Islam which is forbidden by the Wahhabi clerics, who monopolize religion in Saudi Arabia.

He has protested the destruction of Hijazi architecture and Hijazi holy sites by envious Wahhabis, who see the worship of these sites as unlawful religious innovation (*bid’a*). Several of these sites have been destroyed, the most recent amongst them being the Jiyad fortress, built by the Ottomans in the eighteenth century, and destroyed in 2002. The fortress was the site from which Husayn bin ‘Ali started the Arab Revolt in Mecca. It overlooks the Ka’aba, and was removed to make way for a massive, five-story project. The developers of the project are the Bin Ladin Company, which has close ties to the royal family.”

i could never understand all the destruction of islamic sites — including mohammed’s mother’s grave (!) — happening in mecca and medina (see also here). greed (i.e. wanting to build huMONgous hotel complexes to milk the hajj crowds) doesn’t seem to cover it, afaiac. but now that i know that all these sites are in hejazi territory and are connected with hejazi history — and the fact that it’s mostly najdis destroying them — NOW it all makes sense! it’s tribes vs. tribes, that’s all.

previously: historic mating patterns on the arabian peninsula and tribalism on the innerwebs

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historic mating patterns on the arabian peninsula

anybody else getting a little bored with europe and europeans? yeah, i thought so. here’s a little diversion! (i will return to the mating patterns of europeans shortly.)

the arabs. and by “the arabs” i mean the ones on the arabian peninsula. even more specifically, i mean to contrast the arabs living in the hejaz on the west coast with the arabs from the najd in the interior. for a very long time, the hejazi arabs have been quite comopolitan and internationally-oriented, whereas the najdi arabs were mostly camel-herding nomads or settled in and around desert oases. the balance of power between the two shifted beginning in the 1700-1800s when the al saud clan — from the najd region — gained control of the region, and, most importantly, when they eventually acquired de facto control of the nation’s oil.

consang.net tells us that the saudi arabians today inbreed a LOT: 50%+ of all marriages are consanguineous (between second cousins or closer). there is variation within the country though.

from Consanguinity among the Saudi Arabian population (1995) [click on table for LARGER view] …

consanguinity among the saudi arabian peninsula - table 02

… the total consanguinity rate in what the authors refer to as the “north western province” (i think this must be some former provincial designation), which is basically the hejaz region, was 67.7% in 1995. the “central province” — the northern part of the najd region — had a consanguineous marriage rate of 60.8% — so lower than the hejaz region.

i don’t think that this was always the case, that consanguineous marriage was more common in the hejaz region than in the najd region. in fact, i think that the hejazis have adopted cousin marriage more and more over the course of the last couple of centuries thanks to a process of “najdification” that, presumably, the entire country has been undergoing since the al saud clan came to prominence. (also, perhaps many najdis have moved to places in the hejaz region like mecca.)

from Cradle of Islam: The Hijaz and the Quest for an Arabian Identity (2004) [pgs. 77-81]:

Of key interest here is the introduction of what may be called the ‘tribalisation’ of marriage relations amongst the Hijazis. In contrast to past practices of marriage with non-Arab Muslims, marriages now take place within the Hijazi cultural group. The definition of what constitutes a Hijazi for marriage purposes has become more strict….

One implication of ‘tribalisation’, however, is that it draws the cultural form of association that sets the standards for the Hijazis from Najdi life. The emphasis placed on lineage, purity and related ideas confirms the superiority of a particular conception of what a social group should be: a tribe….

“For members of the Hijazi *’awa’il*, establishing and dissolving contemporary marriage relationships is now regulated by several sets of rules and considerations, most of which are relatively recent in origin…. All of these changes are best understood in light of the contrast between the period prior to and that following the Hijaz’s political unification under Saudi rule….

“In the period before Saudi political unification the rules governing marriage derived from largely religious sources, reflecting a very different relation between state and society to that which exists in the present. All contemporary marriage rules are closely related to these earlier ones, either as refinements or entailing new but subordinate principles.

“At the most general level, the Quran is broadly permissive of potential marriage partners: ‘Oh! Mankind! We have created you from a single [pair] of a male and a female, and made you into nations and tribes, that ye may know each other. Verily the most honoured of you in the sight of Allah is the most pious of you.’ There are, however, some qualifications to this open-ended approach. The first is that Islam permits marital ties between Muslim men and non-Muslim women, provided the latter are ‘people of the book’, *ahl al kitab*, i.e. Jews or Christians. The Quran tells male Muslims that, ‘lawful for you are the chaste women from among those who have been given the book’. Muslim women, on the other hand, are absolutely prohibited from marrying non-Muslims. A Muslim woman’s marriage to a non-Muslim is considered to entail illegal intercourse and thus produces illegitimate offspring who are prohibited from inheriting the father’s wealth….

“In addition to religion, considerations of the nature of wider family life have been most influential in regulating marriage. Here the promotion and defence of patrilineal group status is of central significance. Family status is related to the *’ird* (honour) of its male members, which is defended by ensuring the chastity of female dependants. The idea of *’ird* is a key reason why marriage based on overt love has traditionally been considered *’ayb* (shameful): admitting love implies a clandestine pre-marital relationship. Indeed, the idea that marriage should be based on an emotional bond between husband and wife conflicts with the primacy of maintaining well-integrated families; it implies putting one’s personal interests and needs above the extended family’s wellbeing. In this, Hijazis conform to general Arabian attitudes but, as ever, the Hijazi preoccupation with family creates a specific distrust of bonds based on emotion or sentiment….

Accounts of the late nineteenth and early twentieth centuries clearly show that these rules did indeed regulate Hijazi marriages. For instance, being Muslim, regardless of other origins, provided a sufficiently strong basis on which to build marriages. Mecca was a melting pot for the Islamic world, so mixed marriages were common. Marriage made a significant contribution to the heterogeneous and cosmopolitan nature of Hijazi society.

By contrast, Najdi marriage was, and remains within the same lineage, with bonds among the tribal families usually reinforced by patrilineal parallel-cousin marriages. There is, however, an important distinction between *khadiri* (non-tribal, i.e. ‘non-pure’ Najdi), and *gabili* (tribal ‘pure-blooded’ Najdi). Strict patrilinearity allowed *gabili* men to marry outsiders, such as Egyptian, Moroccan or Lebanese women, but their female relatives have never married outside the tribe. In principle, then, men from the Hijaz would not have been able to marry into a pure-blooded Najdi family, while women would, although Hijazi women were not, as a rule, given in marriage to Najdi families, nor were they asked. In this intricate system of social boundaries expressed through marriage practices, Hijazis — both men and women — married from the Asir tribal region more easily than from the tribal Najd….

“Among elite Najdi men polygamy has also been more prominent.”

so it sounds as though the najdi arabs have had a longer history of closer inbreeding than the hejazi arabs.

if we go even further back, there are more hints that the hejazis may have been comparative outbreeders, as far as arabs go anyway. from Close Relationships: Incest and Inbreeding in Classical Arabic Literature (2005) [pgs. 78-81]:

“Much has been written on the extent to which Islam changed or confirmed the existing customs in pre-Islamic Arabia. Data on these customs are scanty…. As for the forbidden degrees of marriage, early Muslim authorities explain that the main differences between pre-Islamic and Islamic customs concerned the marriage of stepmothers and sons, and being married to two sisters simultaneously. Muhammad ibn al-Saib al-Kalbi (d.146/763) praises the Arabs in the Jahiliyya, the period of ‘ignorance’, for anticipating the Qur’anic prohibitions:

“‘The Arabs, in the time of their Ignorance, held things for forbidden that the Qur’an was to declare forbidden. They did not marry daughters or mothers, nor sisters or aunts from the mother’s side or the father’s side. The worst thing they used to do was to be married to two sisters at the same time, or to succeed one’s deceased father as husband to his wife. They used to call someone who did this *dayzan*….

“‘(…) If a man died, leaving a wife, or divorced his wife, his eldest son would stand up and throw his cloak over her if he wanted her. If he did not want her, one of his brothers would marry her, with a new brideprice.’

“Ibn Habib (d. 245/860), who has a nearly identical passage, adds that ‘Islam has separated men from the wives of their fathers; they are numerous’….

“Ibn Habib also states that the Arabs used to marry two sisters….”

not too much about marrying cousins there, but there’s this…

Against the tendency of presenting the pre-Islamic Arabs as being very close to Islam already, others restrict this virtuous behaviour to the inhabitants of Mecca, contrasting them with the Bedouins, as did Yaqut in the passage quoted above….

and that passage from yaqut [pg. 60]:

“In his ‘Kitab al-Arab’ (‘Book of the Arabs’), devoted to the virtues of the Arabs, Ibn Qutayba praises especially Quaysh, the Prophet’s tribe, for preserving something of the old Abrahamic religion, inherited through Abraham/Ibrahim’s son Ismael/Imail; these remnants included ‘circucision, ritual ablution, repudiation of women, manumission of slaves, and the prohibition of marriage with forbidden family members, through kinship, milk relationship, or affinity by marriage’. Yaqut (d. 626/1229) rephrases the same idea: the pre-Islamic Meccans:

‘were not like the uncouth Bedouins. They used to circumcise their sons, to perform the Hajj at the Kaaba; … they shunned marriages with a daughter, a daughter’s daughter, a sister, and a sister’s daughter, because of their sense of jealous honour and in order to keep aloof from the Magians.'”

in other words, perhaps the pre-islamic hejazi were not at all like the pre-islamic najdis (bedouins) … and, perhaps, the hejazi — the population from whence mohammed hailed — didn’t inbreed so much [pg. 81]:

In general, as far as may be ascertained, inbreeding was not very common in pre-Islamic times. It is difficult to obtain precise information. The genealogies of tribes and clans in the pre-Islamic and early Islamic periods, though very detailed, are notoriously unreliable, loaded as they are with politics and sentiments; an alliance between tribes was often cemented by fabricating a common ancestor. Moreover, the genealogies normally present the male lines only and give very little information on females. Among the exceptions are the lineages of the Prophet Muhammad and other prominent early Muslims. Thus Ibn Habib gives Muhammad’s ancestors in the all-female line, going back seven generations. Similar but shorter matrilinear lines are given for Abu Bakr, Umar, Uthman, Ali, and al-Hasan. Only two lines are given in full in these lineages: the all-male and the all-female, out of the theoretical maximum of 128 (2 to the 7th) lines of ascendants that go with a full picture of seven generations in Muhammad’s case. Therefore it is hazardous to draw any firm conclusions. Yet the general picture that emerges from this admittedly limited sample is clear: there may have been ‘irregularities’ by Islamic standards, such as the above-mentioned stepmother-marriages, but the spouses are not closely related and even first-cousin unions, often assumed to be dominant in Arab society, are almost absent as far as can be observed. In the Prophet’s lineage, one finds that his great-grandmother Umm Habib and her husband Abd al-Uzza had a great-grandfather (Qusayy) in common; Uthman’s maternal great-great-grandmother Sakhra bint Abd ibn Imran married her first cousin Amr ibn Aidh ibn Imran.”

perhaps mohammed — who invented a fairly (fairly) universalistic religion — came from a comparatively not-so-inbred population [i.e. the hejazi arabs – mohammed’s tribe, the quraysh tribe, was from mecca]. -?- dunno. difficult to tell, but it’s an interesting question, i think.

previously: inbreeding and the ancient hebrews (and the arabs) and father’s brother’s daughter’s marriage

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“core europe” and human accomplish-ment

uncle bob beat me to this (hey uncle bob! *waves* (^_^) ). i’ve been meaning to post about human accomplishment in core europe ever since agnostic posted about it last month on his blog.

here, from charles murray’s Human Accomplishment, is a map of “concentrations [of accomplishment] within the european core”:

charles murray - human accomplishment map - european core

from murray (via agnostic):

“The colored regions in the European core (light and dark blue together) account for the origins…of fully 50 percent of the total European significant figures. Just the five regions colored dark blue — Ile de France, Southeast England, Tuscany, Belgium, and the Netherlands — account for 26 percent of the European total. The other 24 percent come from (in order of their contribution) Bavaria, Venetia, Southwest England, Switzerland, Lowland Scotland, Lower Saxony, Saxony, Baden-Wurttemberg, Northeast Austria, the Italian Papal States, and Brandenburg….

“Or you can think of it another way: 80 percent of all the European significant figures can be enclosed in an area that does not include Russia, Sweden, Norway, Finland, Spain, Portugal, the Balkans, Poland, Hungary, East and West Prussia, Ireland, Wales, most of Scotland, the lower quarter of Italy, and about a third of France.”


the dark blue area of belgium, the netherlands, ile de france, and southeast england is definitely the core area of europe that — thanks to the early enthusiasm of the franks for christianity and the church’s cousin marriage bans AND the franks’ invention of manorialism — has been outbreeding for the longest amount of time out of all the europeans. (see “mating patterns in europe series” below ↓ in left-hand column for more details.) belgium + the netherlands + ile de france = austrasia, which is where manorialism got started. the franks brought the manor system, and the cousin marriage bans, with them on their trek across/conquest of the east — the light blue bits in germany. there is also evidence for the manor system early on in kent and the south of england, not to mention some very early secular laws against cousin marriage in those parts of england. the manor system was introduced in lowland scotland — along with many actual lords of those manors from normandy — by king david. (no, not that onethis one.)

these areas — along with parts of northern italy (the flat parts) — are what i’ve been calling my “core europe” — the most outbred of the europeans (who are, in turn, the most outbred of almost anybody on the planet). although northern italy — tuscany — i’m not 100% sure about. i have found a little evidence suggesting that medieval northern italians maybe avoided marrying their cousins — and perhaps the genetics backs that up — but Further Research is RequiredTM.

as uncle bob said: “Where there was the most outbreeding there was the most accomplishment. Look specifically at northern Italy, England, and central Europe. I find this astonishing.”

me, too!

map of the “concentrations [of accomplishment] within the european core” with the hajnal line? but of course:

charles murray - human accomplishment map - european core + hajnal line

see also: How Inbred are Europeans? from jayman!

update 09/25: another map from murray’s book [source]:

charles murray - origins of significant figures 1800-1950

previously: medieval manoralism and the hajnal line and behind the hajnal line

(note: comments do not require an email. stomp, stomp, stomp.)

where everybody’s fourth cousins

in response to the “people befriend their fourth cousins” study, smersh makes an excellent observation:

“You referenced some of this in your counter currents interview but this study makes things more clear.

Friends are as close to each other as fourth cousins.

Jews are also as close to each other as fourth or fifth cousins.

Therefore it is easy for Jews to make close friends by hanging out with other Jews.

Meanwhile, it is harder for gentiles to make close friends in mass societies, as people move around and no longer live in a village near a bunch of closely related people.

Certainly seems like it might explain a lot without implying a malicious intent on the part of certain parties.”

yes! maybe.

if it’s correct that people generally befriend their fourth cousins — and this is something that could vary between different populations (Further Research is RequiredTM) — then, perhaps, this could explain why places like iceland work so well, too. i don’t know what the average relatedness there is (does anybody know?), but presumably it’s something like fourth or fifth cousins as well. maybe then it IS really easy in such a place to have a — whatever — redistributive socialist system when it feels like almost anyone in your population could be your friend.


btw, that counter currents interview was, in fact, originally a hoover hog interview that somehow got syndicated over on cc. just want to give credit where credit is due. (^_^)

previously: friendship and natural selection (and human biodiversity)

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consanguin-eous marriage in afghanistan

just for a change of pace.

the consanguineous (second cousin or closer) marriage rates in afghanistan are high. consang.net tells us that the rate is between 40 and 49%. more details are to be had in Consanguineous Marriages in Afghanistan (2012) and Prevalence of Consanguienous Marriages in West and South of Afghanistan (2012), including consanguinity rates by province and ethnic group.

back in the 1970s, joseph westermeyer found that peoples in southeast asia had different mating patterns depending on what elevation they lived at — the higher up, the closer the mating patterns (see also here). this pattern appears to be holding true wherever i look (example) — and now we have afghanistan.

here’s a map of the mean inbreeding coefficients for the provinces studied in the two papers above — higher coefficients indicate greater inbreeding (click on map for LARGER view):

Afghanistan provinces - inbreeding coefficients - colored

aaaaand here’s a topographical map of afghanistan. elevation and inbreeding look to match pretty closely (would be nice to have data from the other provinces, too):


here’s a breakdown of consanguinity rates by ethnicity in the country. the numbers are also sorted here by region depending upon which paper they came from — the first paper dealt with the north and east of the country, the second with the south and west. remember that consanguineous marriages include: double-first cousin marriage, first cousin marriage, first cousin-once-removed marriage, and second cousin marriage:

– north & east –
Turkmen = 48%
Hazara = 47%
Uzbek = 44%
Pashtuns = 43%
Tajik (Shi’a) = 43%
Tajik (Sunni) = 38%

– south & west –
Turkmen = 64%
Hazara = 53%
Sadats = 51%
Tajik (Sunni) = 51%
Pashtun = 50%
Tajik (Shi’a) = 49%

the turkmen in the lead!

interestingly, while there is more consanguineous marriage in the south and west of afghanistan, the inbreeding coefficients are higher in the north and east of the country, indicating that there are greater amounts of closer marriages in those (high elevation) regions. and this does appear to be the case — the percentages of double-first cousin marriages are higher in the north and east:

– north & east –
Turkmen = 8.7%
Pashtun = 7.9%
Uzbek = 7.5%
Hazara = 6.4%
Tajik (Sunni) = 6.3%
Tajik (Shi’a) = 4.0%

– south & west –
Sadats – 3.0%
Pashtun – 2.3%
Tajik (Shi’a) – 1.8%
Hazara – 1.2%
Turkmen – 1.2%
Tajik (Sunni) – 1.1%

i’m going to guess that there’s more father’s brother’s daughter’s (fbd) marriage in the north and east of afghanistan rather than in the south and west, since fbd marriage tends to push towards greater amounts of double-first cousin marriage (and, therefore, greater inbreeding in general). i’m also going to guess that the tajiks really don’t practice much fbd marriage at all, either in the north or the south — except maybe for the sunni tajiks in the north.

how long have the various afghani populations been marrying their cousins? dunno. long time prolly. fbd marriage was most likely introduced to the region by the arabs, so the afghanis probably adopted that form of cousin marriage sometime after the mid-600s.

previously: this one’s for g.w. and the flatlanders vs. the mountain people and kandahar vs. levittown

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the outbreeding project continues apace…

…in the united states! (just as you all suspected.) amongst white folks anyway (that’s who was included in the study below).

from a study published in 2009, Measures of Autozygosity in Decline: Globalization, Urbanization, and Its Implications for Medical Genetics:

This research has definitively shown the existence of a trend for decreasing autozygosity with younger chronological age in the North American population of European ancestry. The ROHs we identified, larger than 1 Mb, are clearly representative of autozygosity due to distant consanguinity in our outbred populations, and not chromosomal abnormalities or common copy number variants. Using our predictive models of decreasing Fld, we show a quantifiable decrease in consanguinity over the twentieth century. Based on data provided in Carothers et al, this decrease in Fld found in our discovery population is on the order of individuals transitioning from a single inbreeding loop 4–5 generations prior, to no inbreeding loops within <6 generations. We postulate that the increased mobility, urbanization and outbreeding in North America in the last century has led to less consanguinity (and thus less homozygosity and homogeneity) in younger individuals.”

the researchers looked at two different sets of genomes — one from the ninds repository @the coriell institute, the other from the baltimore longitudinal study of aging (blsa). the blsa is, obviously, biased towards people on the east coast of the u.s. (in and around baltimore). glancing through the list of submitters to ninds, there’s also something of an east coast bias there, although many samples do come from other areas of the country (see the list of locations at the end of this post).

amongst the findings in this study are that 1) the number of runs of homozygosity (roh) has decreased in white americans over the last one hundred years or so, and 2) the lengths of the roh have shrunk as well. both of these are good indicators of outbreeding.

here are a couple of tables/charts from the paper (click on images for LARGER views):

measures of autozygosity in decline - table 02

measures of autozygosity in decline - percent of genome in roh

what’s interesting to contemplate, i think, is what this might mean wrt selection pressures on americans going forward? especially, what might it mean in light of european-americans encountering other, newer groups within american society that are not outbreeding so much (at least not at the moment) — newly arrived immigrants from many muslim countries, for example — or even, perhaps, latin americans (although i’m not 100% sure about how much they’ve been inbreeding over the past few hundred years or so — stay tuned!). how is that all going to play out? interesting times.

possibly related footnote — here is an abstract from the 2013 ashg conference:

“Reconstructing the Genetic Demography of the United States”

“The United States (U.S) is a complex, multiethnic society shaped by immigration and admixture, but the extent to which these forces influence the overall population genetic structure of the U.S is unknown. We utilized self-reported ancestry data collected from the decennial U.S Census 2010 and allele frequency data from over 2000 SNPs for over 40 of the most common ancestries in the U.S. that were available from the Pan Asian Single Nucleotide Polymorphism (PASNP), Population Reference Sample (POPRES), 1000 Genomes, and Human Genome Diversity Panel (HGDP) databases. We utilized the relative proportions of individuals of each ancestry within each county, state, region and nation and calculate the weighted average allele frequency in these areas. We reconstructed the genetic demography of the U.S by examining the geographic distribution of Wright’s Fst. Shannon’s diversity index, H was calculated to assess the apportionment of genetic diversity at the county, state, regional and national level. This analysis was repeated stratifying by race/ethnicity. We analyzed households with spouses, using the phi-coefficient as a measure of assortative mating for ancestry. This analysis was repeated stratifying by age of the spouses (older or younger than 50). Most of the genetic diversity is between ancestries within county, but this varies by race/ethnicity, and ranges from 95% for Whites to 43% for Hispanics illustrating that the White ancestries are relatively homogeneously scattered throughout the U.S whereas the Hispanic ancestries show significant clustering by geography. Analysis of the mating patterns show strong within ethnicity assortative mating for American Indian/Alaska Natives, Asians, Blacks, Hispanic, Native Hawaiians/Pacific Islanders, and Whites, with φ = 0.30, 0.864, 0.92, 0.863, 0.478 and 0.832 respectively (P<1×10-324 for each) and significantly less correlation in the younger cohort. These results show demographic patterns of social homogamy which are slowly decreasing over time. One major implication is that data collected from different locations around the U.S are susceptible to both within- and between-location population genetic substructure, leading to potential biases in population-based association studies.”

origin cities of the ninds samples (from a quick-ish glance):

Burlington, VT
Lebanon, NH
Boston x 10
New York x 7
Rochester, NY x 4
New Haven x 3

Bethesda x 7
Baltimore x 5
Washington, D.C.

Winston-Salem, NC
Charleston, SC

Birmingham x 3

Jacksonville x 4

Cincinnati x 5
Indianapolis, IN
Ann Arbor

Chicago x 3
Springfield, IL
Rochester, MN
Englewood, CO
Kansas City

Houston x 4

Salt Lake City

Los Angeles
Irvine, CA
Fountain Valley, CA
San Diego x 2
San Francisco x 3

previously: runs of homozygosity and inbreeding (and outbreeding) and runs of homozygosity in the irish population and western europeans, runs of homozygosity (roh), and outbreeding and russians, eastern europeans, runs of homozygosity (roh), and inbreeding

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