the turkana: mating patterns, family types, and social structures

t.greer recommended to me a paper on the mating patterns of the turkana of east africa (thanks, t!): Mating Structure of a Nomadic Pastoral Population (1982).

first, here’s a nice turkana person for ya (^_^):

turkana girl 02

the turkana mating patterns are interesting, i think, for a handful of reasons:

– they appear to uphold the notion that flatlanders tend to be outbreeders (see also here) — while mountaineers/peoples in marginal lands tend to be inbreeders;
– they also appear to uphold the notion that the greater the outbreeding, the looser the family and social structures (see…half of the blog);
– and they appear to contradict the notion that pastoralists tend to inbreed (see explanations from anthropologists the world over). hmmmm.

from the paper, the turkana live here in kenya:

turkana - map

and this region of kenya is fairly flat:

kenya - topography 02

the turkana who practice pastoralism (most of them — a few are agriculturalists) apparently do bring their herds (of camels and goats) uphill for grazing in the summer, but mostly they reside in the valleys, and they consider themselves to be flatlanders rather than mountaineers.

from the paper, we learn that the turkana have clans (28 patrilineal clans) [pg. 472], that they avoid marrying within those clans — in the study, 96% of those surveyed were married to someone from another clan [pg. 474], and that they even try to avoid marrying anyone closer than second cousins [pg. 472].

(one thing that the turkana do have which complicates the picture is polygamy. clearly polygamy, like cousin marriage, also results in closer relatedness [a lot of individuals in the population are half-siblings]. i haven’t thought through polygamy yet — what it means for relatedness. obviously it depends on if only a certain portion of the males get to mate and the remainder are left out or if the whole system is more of a rotating system of polygamy and women are swapped between most or all of the men. polygamy is complicated. i’ll have to think about it one of these days.)

so, what is turkana society like? what are their family types like? what about these clans then?

from Turkana (1996) [pgs. 16, 20-22]:

“The nuclear family is the basic social and political unit among the Turkana.”

uh…kinda.

“The family comprises a man, his wife or wives, his sons and their wives and children, and his unmarried daughters. In the homestead there might also be a grandparent or other relative and a concubine (a woman living in the household to whom he is not married).

“The man is the head of the family. The family is represented economically by its herd of livestock….

“The Extended Family

“Among the Turkana, the extended family (*ngi-tungakothi*) is made up of all males who can claim common descent on the male side. The unit could go back three or four generations. To members of the group, those within it are ‘our people.’ But strictly speaking, the extended family also includes the wives of each of these men if they have raised a child to walking stage. It excludes women who have married elsewhere and are no longer in the family.

“The core of the extended family, however, is essentially the son of a deceased father, his full brothers, his half-brothers, and his paternal male first cousins, along with the nuclear families of all these men…. Members also share fellowship on other such occasions as initiation, weddings, and judicial compensation, when there is mutual assistance in givings and receiving livestock.”

“judicial compensation” there is interesting. is that like wergeld? dunno. will have to find out more.

“The Clan

“Every Turkana belongs to a clan (*ateger*), of which there are about 20. They fall into two major types: the large, widespread clans, each comprising over 1,000 adult males, and the very small ones consisting of only about 30 members.

Clans are of little practical or political importance to the Turkana today, especially since clans no longer own herds or pastures or watering places…. Nor do travelling Turkana any longer expect help or hospitality from fellow clansmen. They would expect that help from bond-friends, people in various parts of the country to whom they have made a ritual commitment.

“bond-friends.” also very interesting.

from The Evolution of Human Societies: From Foraging Group to Agrarian State (2000), we learn that the turkana’s family and social structures are, indeed, really loose, and the whole “clan” structure seems to mostly be a system used to maintain the outbreeding (the exogamy) — a way to keep track of whom you’re not supposed to marry [pgs. 197-99]:

“Dyson-Hudson and McCabe (1985: 79-80) describe the degree to which Turkana groups form out of myriad individual decisions:

“‘Kinship, both agnatic and affinal, is an important basis for cooperative relationships. However since livestock are a readily partible resource, and since the frequent moves of camps and splitting of the major *awi* into satellite camps allow the breaking of old bonds and the establishment of new ones, a man has great latitude to choose to live with people he likes. A woman also has some choice: she can live with her father, her brother, or her grown sons, as well as with her husband. Flux and flexibility characterize [their] social networks.

Although the Turkana lack highly structured kin groups, territories, and a formal political system, they do establish and maintain large networks that amount to a kind of effective community for each homestead. First, hamletlike groups of close relatives and friends live and move together for part of the year. Second, such groups cluster within convenient walking distance of one another, and men in such a cluster meet often to take turns distributing freshly slaughtered meat and to share information on herds and pastures. These two levels of social organization (Gulliver calls them primary and secondary neighborhoods) provide the individual househead with a network of friends through which food and information flow, friends from whom he may beg insistently as a good Turkana should (Gulliver 1951; Patton 1982) and who will cooperate with him in defense against raiding. Although a family is free to move at will, in practice families tend to move with their neighbors and settle near them at new locations….

“The main cement of Turkana social organization, however, is the exchange of livestock. A nuclear family’s herds are all owned and managed by the father; and although their daily care falls to women and boys, spread over the countryside, there is a strong sense of the essential unity of the family and its herd. Some hamlet groups are the remnants of old extended families whose senior male has died: in such cases the brothers and in-laws continue to live near each other, and, because their herd once had a common owner, the men continue to feel part of one family. Often, as we have seen, the hamlet-size group also includes friends….

“How extensive is Turkana social structure? On the one hand, there are indicators of ‘tribal’ integration. The Turkana say, ‘We are all brothers,’ and respect this tribal identity by rarely raiding or using spears against one another (bandits, *igorokos*, are exceptions). They know and acknowledge the ‘territorial’ names of their regions. They also belong to clans, some of them small and localized, others widespread throughout Turkana land. In past times, apparently, whole regions of Turkana mustered thousands of warriors against non-Turkana enemies.

Yet in their daily life the Turkana are not conscious of themselves as a tribe. They have no tribal, territorial, or clan leaders, no corporate groups, and no genealogical reckoning beyond the grandparent level. They are highly individualistic and tend to migrate within circumscribed areas; even close-knit extended families usually separate at times in response to their individual needs….

also, from here:

There would appear to be no clan leadership or organisation. Gulliver states that ‘if one asks a Turkana who is head of his clan he usually replies *there is no head, we have no heads. They were all long ago.* However a few will give the name of a man of a clan recently alive, or an old man, who achieved fame and importance for some reason and say that he is the head. But enquiry shows that he has no authority over any of them outside his own extended family should he still be alive…’ (1951: 69).”

so, the turkana outbreed, and they have loose family and social structures. friends seem to be important (as important as family?). the turkana are individualistic, yet share readily with their friends.

they do go to battle, though. mostly with non-turkana peoples. sometimes the non-turkana steal the turkana’s animals, oftentimes it’s the other way around [from here]:

“Warfare is traditionally an essential part of Turkana life and the principal occupation of young men. Weapons are considered a man’s proud possessions and the practical tool for increasing herds by raiding and for expanding their territory. Ever since they entered Kenya, the Turkana have been in a perpetual process of expansion. Previously settled tribes such as the Samburu, Pokot, Donyiro, Toposa and Karamojong were forced out of their territory by belligerent Turkana warriors (Gulliver, 1951: 143). No administration has ever able completely to contain the Turkana and put an end to these conflicts. These common age-old pursuits still trouble independent Kenya.

Turkana believe that all livestock on earth, including that owned by other people, is theirs by right, and that there is nothing wrong in going after it and taking it by force. A young man, they say, must be prepared to die in pursuit of stock (Soper, 1985: 106).”

i love how people justify their own actions to themselves. (~_^) don’t mess with the turkana, though! they have wrist knives. yikes!:

turkana wrist knife 02

(note: comments do not require an email. fighting with wrist knives! (O_O) )

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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.

dunno.

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)

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

friendship and natural selection (and human biodiversity)

i linked to this paper…

Friendship and Natural Selection

…in this past sunday’s linkfest, but, to be honest with you, i hadn’t actually read it. (yeah, i do that sometimes. ok, ok — a LOT of times!)

since then, a couple of people urged me to read the arXiv blogpost on it (thanks @DKshad0w and @SamoBurja!), which prompted me to read the orig. research paper and … wow! … mind. blown.

now, no, i’m NOT a geneticist — i don’t even play one on the innerwebs — so i’m not your gal for evaluating whether or not these guys — nicholas christakis and james fowler — have done their work right, but if they have, this is very cool stuff:

Pairs of friends are, on average, as genetically similar to one another as fourth cousins, which seems noteworthy since this estimate is net of mean ancestry and background relatedness.”

fourth cousins! note that these are (i believe) all white folks. the data are from the framingham heart study, but the researchers do say that they controlled both for relatives (i.e. that individuals might be “friends” with people who are, in fact, distant relatives) and ethnicity (eg. that italians might just be friends with other italians).

It is intriguing that genetic structure in human populations may result not only from the formation of reproductive unions, but also from the formation of friendship unions. This in turn has relevance for the idea of an evocative gene-environment correlation, proposed more than 30 years ago, which suggests that a person’s genes can lead one to seek out circumstances that are compatible with one’s genotype. Our results suggest that these circumstances could include not only the physical environment but also the *social* environment, and hence the genotypic constitution of one’s friends. As Tooby and Cosmides argue, ‘not only do individual humans have different reproductive values that can be estimated based on various cues they manifest, but they also have different association values.’ People may seek out particular, convivial social environments that affect their fitness.

i’ve been saying for a while now that the family types/social structures in which individuals are located ought to be taken into consideration when thinking about the fitness of those individuals and how natural selection might be working on different individuals living and reproducing in different sorts of social structures (individuals living in nuclear family structures versus large clan structures, for instance). i’ve mostly been thinking about family structures, but christakis and fowler are talking about friendship structures — alliances with non-family members. cool!

“The existence of excess genetic similarity between friends is also relevant to the growing area of indirect genetic effects, wherein the phenotypic traits of focal individuals are influenced by the genomes of their neighbors, in a kind of ‘network epistasis.’ In fact, our results support the idea that humans might be seen as metagenomic not just with respect to the microbes within them, but also with respect to the humans around them. It may be useful to view a person’s genetic landscape as a summation of the genes within the individual and within the people surrounding the individual, just as in certain other organisms.

yeah. just muse on THAT for a while. (~_^) and then try this on for size…

“[T]he human evolutionary environment is not limited to the physical environment (sunshine, altitude) or biological environment (predators, pathogens), but also includes the social environment, which may itself be an evolutionary force. Our finding that positively correlated genotypes are under positive selection suggests that the genes of other people might modify the fitness advantages of one’s own genes, thus affecting the speed and outcome of evolution.

did you get that? the researchers found that, the SNPs that were most common between the friends (the homophilic SNPs), have, indeed, been under recent positive selection:

“To test the hypothesis that homophilic SNPs are generally under recent positive selection, we use the Composite of Multiple Signals (CMS) score. This score combines signals from several measures of positive selection to create a single value that indicates the likelihood a SNP has been increasing in frequency due to selection pressure over the last 30,000 years (see SI). In Fig.3, we show that, after correcting for correlated outcomes due to linkage disequilibrium and for varying precision in the GWAS estimates (see SI), the top 20% most homophilic SNPs have significantly higher CMS scores than the other 80% (+0.07, SE 0.02, p = 0.003)…. In contrast, Fig.3 also shows that CMS scores are not significantly higher for the most homophilic SNPs in the strangers GWAS (–0.00, SE 0.02, p = 0.86). This suggests that the whole-genome regression model we use does not generate false positives…. In sum, it appears that, overall, across the whole genome, the genotypes humans tend to share in common with their friends are more likely to be under recent natural selection than other genotypes.

friendship and natural selection 01

friendship and natural selection 02
_____

with human biodiversity in mind, my question would be: do all peoples everywhere form an equal number of friendships with (technically) unrelated individuals? yes, i have an obsession with clannish peoples — but, seriously — do people who live in clans or tribes make as many “friends” as peoples who don’t? do they even have the opportunity? if not, what might this mean for natural selection in those populations?

(note: comments do not require an email. friends.)

mating patterns, family types, social structures, and selection pressures

i’ve mentioned this before (see here and here and here), specifically wrt family types like nuclear families vs. clans, but i thought i’d bring it up again:

more attention ought to be paid to things like mating patterns, family types, and the social structures within societies as creating different sorts of selection pressures for different types of individuals — personality types, iq, other behavioral patterns, etc.

some researchers have been looking at how, for instance, mating patterns can affect genes and genomes in populations: cochran and harpending have been investigating paternal age and mutation rates, some of greg’s low-hanging fruit (double entendre NOT intended), and hage and marck discovered how matrilineality and matrilocal residence affected the distribution of y-chromosome haplogroups in polynesia (other researchers have done similar research for other parts of the world) — and these types of research are really interesting and very exciting, but they’re not quite what i’m talking about.

here’s one example of the sort of thing i’m interested in asking (and answering!): what sort of persons succeed in reproducing the most in a society based on the nuclear family versus a society based around extended families or even clans? what sort(s) of personalities do they have? how high of an iq do they need? what other types of behavioral patterns do they exhibit?

gregory clark famously found that, over the course of the medieval period in england, it was the hard-working, thrifty, forward planning folks with middle-class values who reproduced the most. but he made next to no (actually i think it was none whatsoever) mention of the prevailing family type in medieval england: the nuclear family, which was well-established by at least the 1200s.

imagine what sort of people would do well — what sorts of traits would be selected for — in a society which was based on the individual and his nuclear family making it on their own — with a little help from immediate family and, most importantly, friends and neighbors. someone trustworthy? and trusting? someone who can plan ahead, because those who don’t can’t rely on falling back on an extended family/clan? someone with not the lowest iq in the world?

and what sorts of people do well in a clannish society? those who believe in putting family first ahead of friends and/or the wider community? those who trust their family members more than outsiders, because the outsiders have always had their own family members that they prioritized? individuals who don’t feel a strong urge to plan that far in advance, ’cause hey — uncle joe or cousin ahmed will be there to help out when times are tough? too many individuals who are not so bright because their brighter relatives support them and their offspring?

here, once again, is my favorite example of how at least some clannish societies work. (see if you can spot the potential dysgenic practices!) this is from modern-day egypt — upstream which is much more clannish/tribal than the delta region of the country — Development and Social Change in Rural Egypt (1986), pgs. 150-51:

“The importance that poor peasants attach to the brokerage services by a single wealthy patron can be seen in the continuing importance of the extended family unit in rural Egypt. In the village of El-Diblah [pseudonymous village representative of upper egypt], as well as other Egyptian communities, politics and much of life itself are organized on the basis of large, extended families numbering 500 members or more. These extended families are broad patrilineal structures, which may or may not be able to trace themselves back to a single historical founder. While these extended families do not represent monolithic social structures, most fellahin are animated by a real feeling of belonging to a particular extended family unit. When they need a loan or help with outside government officials, poor peasants will often turn to the leader or a prominent person within their extended family. In the village of El-Diblah three of the four leading extended families are headed by rich peasants. In the eyes of most fellahin, this is exactly as it should be. In the countryside wealth acquired by virtually any means provides a good indication of an individual’s ability to deal with (or against) the ouside world.

“‘Zaghlul,’ for example, is the rich peasant head of one of the leading extended families in El-Diblah. A short, wiry 55-year-old fellah, whose dress and mannerisms are almost indistinguishable from those of other peasants in the village, Zaghlul now owns about 25 feddans of land. Much of this land is planted in sugar cane, a crop that he uses to supply his own cane press that produces black molasses for local sale. As the owner of 25 feddans of land, and the proprietor of one of the few ‘manufacturing’ enterprises in the village, Zaghlul is able to dispense a wide number of agricultural and non-agricultrual work opportunities to favored members of his extended family. Many of the poorer members of his extended family live in a mud-brick settlement surrounding Zaghlul’s modern two-story, red-brick house. In the evenings a steady stream of these poor people come to Zaghlul’s house, seeking brokerage and intercessionary services (for example, help in securing agricultural inputs and medical services from the government)….

mating patterns matter. family types matter. social structures matter. all in the sense that they (i think) set up selection pressures for different sorts of traits — or at least they can do. no doubt they cannot be looked at in isolation (one needs to consider all sorts of other life factors, too, like economic structures), but i think they’re probably pretty important — and need more attention. from this perspective, i mean.

previously: a sense of entitlement and clannish dysgenics and inbreeding and iq

(note: comments do not require an email. low-hanging fruit.)