Certainty in nonpaternity among the Himba of Namibia

Over the years one issue I’ve revisited over and over is that paternity certainty is quite high in Western societies (and from the spotty evidence we have, in most Asian and Middle Eastern societies as well). The reason this is interesting or of note is that there is an urban myth that 10% or so is the incidence of misattributed paternity. That is when children and fathers believe that they are biologically related, but they are not. The true rate in Western societies seems to be 1-2% (and, from what I have heard about Y chromosomal studies in Arab countries, it is at least as low in those societies).

Some of the confusion arose because early genetic testing was done in paternity determination laboratories. For obvious reasons, this is not an unbiased sampling of the general population. Even here, in only 30% of the cases did it turn out that “you are not the father.”

But is this universally true? There was already evidence that even in a Western modern context the extra-pair paternity rate was not always 1-2%. The frequency increases the lower down on the socioeconomic ladder you go.

A new paper in Science Advances, High rate of extrapair paternity in a human population demonstrates diversity in human reproductive strategies (open access), presents the case of

– almost 50% extra-pair paternity rates
– extremely high paternity certainty, which seemed to match whether the child was the biological offspring of the father

What I’m getting at here is that this paper is pointing to a situation where the extra-pair paternity rates are high due to non-marital liaisons, but the individuals in the community as a whole are quite clear of the situation. There is no great deception.

In the discussion they conclude:

These data provide a stark contrast to the prevailing opinion in the genetics literature that EPP is negligible in humans. While Himba may be at the far end of the range of human variation on this trait, they are not alone in having frequent concurrent partnerships. To assess the true range of variation, more studies from a wider variety of economic and social settings are needed. In addition, we currently know very little about what factors might contribute to variation in EPP among humans. Higher rates of female concurrency have been linked to matrilineal inheritance, reliance on foraging and horticulture, a male-biased adult sex ratio, and prolonged periods of spousal absence (11, 25). However, causal links between these traits and the rate of EPP are opaque at best.

In the specific case of the Himba, their pastoralist economy may play a role here. There is strong gender segregation insofar as men and women play distinct economic roles, and the men spend a fair amount of time away from their wives. Additionally, women and girls are critical economic producers, and they are placed in arranged marriages at a very young age. It does not take much imagination to entertain the possibility that economically semi-independent young women married off against their free choice to strange men, who are often away, may regularly form other relationships when opportunity and inclination arose.

The more general question and phenomenon being highlighted here is the nature of human cultural variation. There have long been debates around evolutionary psychology and “human universals.” There is clearly something here, but the field of cultural evolution has shed light on the reality of a high degree of plasticity of social forms. But these forms are not arbitrary in their distribution. Many societies seem to have moved toward a lower frequency of extra-pair paternity, combined with more “mate guarding.” Why?

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20 thoughts on “Certainty in nonpaternity among the Himba of Namibia

  1. What I find funny about this, and this will be a (possibly unnecessarily acid) tangent for many readers of this blog, is I’m kind of aware that you have this trend around @evolving_moloch’s blog / twitter where he has been going on a sort of one-man jihad against all that pop evo-psych that postulates that men are competitive, egoistic, violent, etc because of female sexual selection.

    No, says the lordly @evolving_moloch, this is all due to male competition dynamics and the political power of old males in arranging marriages for young women with men of a particular type. Female sexual selection does not, cannot, have existed as a prominent force in human evolution. It weren’t women wot made men, who then made ‘the patriarchy’ (women did not make the oppressive structures which constrain them, by proxy – they are free from that ‘original sin’). Evo-psych types are ignorant of the “vast, empirical” anthropological literature, no matter how consistent observations are with a sexual choice mechanism.

    Then you get actual non-paternity in the Himba. 40%. And the arrangement of marriages doesn’t matter very much.

    Guess female choice *is* back on the table for one plausible factor (not necessarily the only one) reinforcing ‘why men are what they are’?

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  2. Many societies seem to have moved toward a lower frequency of extra-pair paternity, combined with more “mate guarding. Why?”

    “I know, I know [frantically waving hand]. Please call on me teacher!… Um, well I think …”

    Is it that with more advanced technologies (pastoralism, agriculture, manufacturing) & the associated economic consequences, paternal investment (including the growing importance of inheritances) became increasingly important for the fitness of offspring, and the socially recognized fathers wanted to ensure that they were the biological fathers?

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  3. The frequency increases the lower down on the socioeconomic ladder you go.

    The lower one goes down the ladder, the less likely and able will the individual be able to avail himself of the institutions, like formal adoptions, that deal with domestic issues like unwed mothers. The informal adoptions that occurred in the lower classes could confound the measurement of paternity.

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  4. Interestingly, extra pair paternity was found to be very low (as well as high paternal certainty) in another sub-Saharan African farming society (the Dogon ethnic group of West Africa), with an average of only about 1-2% extra pair paternity, with it lowest among those who practice the traditional tribal/ethnic religion (but still low among others) — it is interesting that paternal certainly is still high among the Himba despite their high rate of extra pair paternity. The Dogon marriage system seems to be generally/more or less similar to to those of many other Niger-Congo-speaking groups in West Africa, particularly the patrilineal groups (which make up the majority of West African ethnic groups).
    See:
    https://www.pnas.org/content/109/25/9781

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  5. Edit to above post:
    “Interestingly extra pair paternity was found to be very low (and paternal certainty found to be high)…”

    Also, the above comment (regarding the West African Dogon and their low EPP rates) is mine as well – I signed in with my full first name by mistake (and had intended to sign in as “Jm8” as usual.

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  6. Interestingly another study shows a very low rate off extra pair paternity (as well as a high rate of paternal certainty) among another sub-Saharan farming group (the Dogon ethnic group of West Africa) with extra pair paternity rates at only about 1.5-2% (with EPP rates being lowest in those that adhere to the traditional Dogon religion but also low among those that do not. It is interesting that the Himba have high paternal certainly despite their high rate of EPP. The marriage system of the Dogon is broadly similar to those of many other (non-Bantu) Niger-Congo-speaking West African ethnic groups, particularly the patrilineal ones (which make up the majority of West African ethnic groups and of which the Dogon are one) and especially those of the greater savanna region.

    See: “Religion as a means to assure paternity” by Strassmann et al.

    (I hope this post is not duplicate, and apologize if it is. I made a similar post earlier and it did not appear, and so have attempted to repost.)

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  7. “The more general question and phenomenon being highlighted here is the nature of human cultural variation. There have long been debates around evolutionary psychology and “human universals.””

    There is a school of thought in the social sciences, especially economics and comparative anthropology, which I think has a lot to be said for it, that argues that human cultural variation is largely a function of economics and technology, and that in given economics circumstances with given technologies that there are “human universals”, even though there is human cultural variation over time and space because the economic circumstances they face shaped, in part, by technologies, are different.

    “Universals” is probably too strong. But, for example, demographic transition is, at least, a pervasive feature of economic development in the vast majority of societies except for some very small relict populations.

    This is a useful lens, I think, within which to understand, for example, changing gender and marriage and family structure norms within the U.S. As what our economy values has changed, the cultural scripts that are most functional change.

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  8. The question is a more fundamental one about the human nature. Mammals in general evolved by increasing learning and social imitation. The higher evolved, the bigger brained and more intelligent they are, the less they rely on instincts. This means they have to learn basics and if they learn the basics wrong, they go wrong.

    Because of this, humans have a great deal of “behavioural creativity”. From the biological perspective, culture should just bridge the gap between the lack of instincts and individual learning by collectively imitating behaviour.

    Now humans with their “behavioural creativity” can develop all kinds of behaviours, even act, from a rational and biological perspective, insane, counterproductive, irrational, destructive.

    The general rule is, that the smaller a group, the more isolated from others, the more likely they are to develop “strange behaviours”. In our modern Western society, we might think of sects and sect-like groups, including some business cultures. Some of these behavioural norms were and are just sick and fairly unlikely to have spread to the general population. But within a family, a group of families, or a close knit firm, they could evolve and persist.

    So the first precondition for inefficient cultural practises is protection from direct competition. Its the same as with genetic traits or in economic relations. Less efficient strategies can survive if there is no competition, but the trait is sufficient for survival on its own.

    That’s why the most efficient and advanced genetic, cultural and economic developments came, as a rule, from developmental centres. Between the cultures and populations from within these developmental centres of large metapopulations could be still big differences. But if a group would have had genetic, cultural or economic traits and strategies which were not competitive enough, it would have been replaced rather sooner than later.

    Protection through isolation is one way to keep up less efficient behaviour. The second possibility is superiority in other fields. Like with two boxers of which one is much bigger, stronger and has a harder chin, which is fighting a little guy. The big one can make many mistakes without losing instantly, the small guy is not allowed to make a single one. The big one can still lose, by making just mistakes and behaving stupid in a row. So his strategy and population might eventually be replaced, even though it had all the advantages in its hands.

    But if starting from a very high level (cultural achievements, economic status and population size for example), a population can do a lot of stupid things and still not being defeated by others because of their head start before their detrimental behaviour became overly dominant.

    That’s also why we don’t have a culture, so far, which is in all respects “better”, because most cultures were only selected for surviving and thriving, not for improving beyond that. And because of the human behavioural creativity, harmful cultural creations will always pop up, rather sooner than later.

    In my opinion the rather inefficient cultural creations being particularly strong in isolated, rather simple societies and the most evolved ones which tipped to decadence because of their general advantages.

    The strongest group selection and competition will be seen in the middle. There you will still see a lot of variation, but some culturally transmitted behavioural norms will repeat themselves like patriarchy, marriage arrangements (no random female sexual selection), rather strict sexual moral and hard punishment for female adultery etc.

    Almost all higher cultures and practically all populations in competitive regions developed these traits. Aberrations exist, but mostly in isolated and fringe areas and definitely more common on the simple or decadent-end level.

    That’s because these rules give a group of people more stability and allow its males to expand, while protecting the own females (of the clan, tribe, nation etc.) from foreigners. A group of people has in most cases little to nothing to win from allowing foreign males to take domestic females. They can win by taking themselves foreign females, especially if there is, in a certain phase or region, a shortage of females of their own group or gene flow is advised for a local adaptation.

    To “give away” the own females or allowing them to “pick and choose” males as they like is a dead end strategy in a competitive environment. You can exchange females by exogamy, but you must control the flow. This means no winner gives away its own females for nothing in return. Only losers can be forced to do so. That’s why, among equal marriage exchange partners, the exchange will be reciprocal. Quid pro quo!

    Similarly even within the own group, if females can choose freely, change partners like they want and commit adultery, they subvert the group moral and cohesion, both among males and females. This is even more of a problem if the groups are fairly large and live for longer times closer together, like in the cold winter region, but also and even more so in the South, with the introduction of settlements and the more advanced technologies and economy.

    I have absolutely no doubt that, from time to time, even in the central parts of Eurasia, clans and tribes might have decided to “live differently” and forget about the basic societal rules. But they never lived long or successful enough, because of their dysfunctional decision, to make an impression.

    There are objective criteria for cultural norms and behaviours, for evaluating their functionality. Calculating whether they are helpful, neutral or detrimental for a people practising it. Like the Skopcen which castrated themselves:
    https://de.wikipedia.org/wiki/Skopzen

    You can act completely insane, even suicidal as a group, follow “your own cultural norms”. But some concepts like those of the Skopcen didn’t suffice to survive on their own, others can’t stand the competition with other groups. Competition is the key factor.

    The problem is that different levels of genetic, cultural and economic competition overlap for the success rate. Which means some cultures believed they were superiour to another because of their own idiocies, while not even realising what they did right! Like a religious fanatic which thinks his people won because he prayed enough, made the offerings and followed the dogmatic rules. Instead of looking at his people’s marriage pattern, family structure, fertility and fanatism in war.
    What he thought was the reason for his success was just a side effect or distant precondition. If another people would have had the same marriage pattern, family structure, fertility and fanatism in war WITHOUT the praying, offerings and dogmatic rules, they would have been the winner.
    But a people able to analyse human behaviours and cultures in a rational way are, which is their fault, most of the time already too decadent to care for “such primitive considerations” anyway, as long as they can still feed on the advantages created by the generations before them and believing a refined culture is protection enough.

    That’s the cultural rise and decline we see quite often. Even within one system, like in the Eurasian steppe, the Near East or the Maghreb. The winning tribe got the spoils of war, got more sedentary, fed itself and became lazy, didn’t move out on the steppe, became reluctant to fight. Might even have relaxed morals and cared less for his relatives. Then the next “barbarian” came in and the game started anew. One could mean that this vicious cycle would have been broken by now, with all the knowledge created, but I doubt it looking at where we are going.

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  9. One also wonders whether, among the Himba, the biological fathers (since they are usually known) also (along with the mother’s husband) play a perhaps significant role in the socialization and provisioning (etc.) of the children – that is in the cases where the biological father and mother’s husband are not the same person. The arrangement in that case might then be similar to those of some native South American tribes (mostly around the Amazon) that believe in forms of “partible paternity” (in which a child is understood to have more than one/many fathers.
    Also, since the Himba are matrilineal, one would also likely expect a significant role for the mother’s brother/maternal uncle in childrearing/socialization/provisioning, as is the case in many matrilineal cultures.

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  10. @Justin: I can write you if you give me a mail.

    @Jm8: Another question is how the different fathers of a woman’s children being related with each other. Like in some polyandric societies the husbands of the women are brothers.

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  11. (Minor) Edit to last comment:
    “One also wonders whether, among the Himba, the biological fathers (since they are usually known – and presumably the children are also aware of their biological parentage) also (along with the mother’s husband) play a perhaps significant role…”

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  12. @Obs
    That is an interesting point/question. In most polyandrous cultures the husbands are indeed brothers (or otherwise related).

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  13. “The reason this is interesting or of note is that there is an urban myth that 10% or so is the incidence of misattributed paternity”

    I greatly enjoy reading your interpretations, and linkages between data. The nuance is useful.

    Just a little medical history. Large scale blood typing started after WWII. The “urban myth” of paternity was based on blood type matching from large, northern US city data from the 1950’s (Chicago, Detroit etc). It did range as high as 10%, it was correlated with socioeconomic measures.

    Perhaps more importantly for this discussion was that the majority of fathers involved were actually aware the child wasn’t theirs.

    This was of course pre birth control.

    Clearly the context of partner availability is important. Would be interested to know how resources are inherited in the Himba context. Is it only the biological offspring that inherit? Do children from an external partner inherit?

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  14. “Some of the confusion arose because early genetic testing was done in paternity determination laboratories. ”

    I first heard a high number for non-paternal results in the late 1990s – it was the result of testing of couples for lethal or seriously damaging recessives. No bias there – just couples coming in to see if their babies would have a high probability of pathology.

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