Cognitive ability of indigenous Arctic peoples

 

In cold environments, human cognitive ability was an adaptation not to resource scarcity, as is often claimed, but to an abundance of resources that could be exploited only through a high level of planning, coordination, and tool development.

Caribou on Thelon River (Wikicommons – Cameron Hayne)

 

 

A reader has asked me, via Twitter: “Do you have any articles as to why the IQ of Siberian and Inuit peoples is lower than Northern Europeans despite similarly cold climate?”

 

Actually, indigenous Arctic peoples seem to be close to the global maximum of cognitive ability. It is also true, however, that the maximum is at more temperate latitudes, specifically within two broad regions:

 

·         East Asia – this is a “plateau” of populations with consistently high mean IQ, i.e., Chinese, Koreans, and Japanese. For Unz (2013), this plateau arose during the time of recorded history through the upper classes continually replacing the lower classes: “Each generation, the poorest disappeared, the less affluent failed to replenish their numbers, and all those lower rungs on the economic ladder were filled by the downwardly mobile children of the fecund wealthy.” A secondary cause was the imperial examination for civil-service jobs: "in China the proud family traditions would boast generations of top-scoring test-takers, along with the important government positions that they had received as a result."

 

·         Europe – this second plateau likewise arose during the time of recorded history, at first slowly during antiquity and then more rapidly during the late medieval to early modern period (Clark 2007; Woodley 2017). The latter increase was driven by expansion of the middle class, particularly by craftspeople who participated in the proto-industrial revolution of the 15th to early 19th centuries. There are thus “peaks” in the plateau, notably Ashkenazi Jews and the descendants of cottage-industry communities in Ulster, Lancashire, Yorkshire, Brittany, Flanders, Alsace, Westphalia, Saxony, the Zurich uplands, the Piedmont, and Lombardy (Cochran et al. 2006; Dunkel et al. 2019; Frost 2007; Piffer 2019; Seccombe 1992, pp. 205-217). Those communities contributed disproportionately to European population growth through early marriage and high childbearing, thus changing Europe’s cognitive landscape (Seccombe 1992, pp. 205-217). 

      The fatalism of serfs gave way to the rationalism of craftspeople: "The life-choices that structure family continuity through time had more predictable consequences; critical objectives could be achieved more regularly. Increasingly, the problem of uncontrolled randomness in life's fortunes was addressed through the calculus of probabilities, rather than through ritual, prayer, pleas for divine intercession, and stoicism ..." (Seccombe 1992, p. 212). 

There is another high-IQ peak among the Finns (Piffer 2019), for reasons that remain uncertain (Late transition from hunting to farming? Absence of serfdom?).

 

If cold climates select for cognitive ability, why do we find maximum cognitive ability at temperate latitudes? This is the apparent contradiction I address in my 2019 paper. In short, I argue that cold climates selected for cognitive ability only when humans were hunter-gatherers. This selection was driven not by resource scarcity, as is often claimed, but rather by an abundance of resources that could be exploited only through a high level of planning, coordination, and tool development (Frost 2019). With the advent of farming, and increasing social complexity, the pressure of selection shifted southward to environments that imposed new cognitive challenges: literacy and numeracy, state formation, laws and law enforcement, social stratification, expansion of the built environment, growth of music, literature, and the fine arts, development of religious beliefs and practices, construction of roads and other infrastructures, and so on.

 

This cognitive evolution initially went farther in the Middle East. Then, sometime around the 16th century, that region seemed to hit a ceiling as the pace of social complexification slowed down. The slowdown had several causes. First, there was demographic stagnation and loss of food production, due to the cumulative effects of erosion, salinization, and overgrazing. Second, there were ideological constraints. Although Islam was not alone in seeking to limit the free expression of ideas, it was more effective than Christianity in preventing the rise of a secular intellectual class that could spur progress in science and technology. Third, a true market economy failed to develop in the Middle East. The concept of trade was widely understood, but production of goods and services remained mostly within the household, i.e., family members, servants and, more broadly, relatives and in-laws. As a result, the market could not replace kinship as the main organizing principle of society.

 

Finally, and perhaps most importantly, cognitive evolution continued in Europe and East Asia because their lower classes were continually replaced, demographically, by their middle and upper classes. This process, described by Gregory Clark for England and Ron Unz for China, has three key elements:

 

1. Social class correlates positively with IQ.

 

2. Social class correlates positively with reproductive success. Lower classes fail to reproduce themselves, whereas higher classes more than reproduce themselves.

 

3. There are no barriers to downward social mobility. Lower classes are thus continually replaced by the demographic overflow of higher classes (Clark 2007; Unz 2013).

 

These three elements are not universal. Hunter-gatherers and simple farming societies have little or no social stratification. Other societies are stratified but have no State that can monopolize the use of violence. There is instead an ongoing free-for-all that selects for ruthlessness, charisma, and the ability to mobilize male violence. Finally, some societies are so stratified that downward mobility is impossible. Social classes are permanent “castes.”

 

In sum, cognitive evolution was initially driven by cold climate at higher latitudes and later by increasing social complexity at lower latitudes. Some higher-latitude groups then moved south to exploit the opportunities being created by increased social complexity. Those groups were not the ones who initiated the transition to farming, sedentism, and social complexity. Instead, they arrived after the fact, being cognitively pre-adapted for the opportunities that others had created and thus better able to pursue this evolutionary trajectory (Frost 2019).

 

Studies of cognitive ability in Arctic peoples

 

To return to the original question, indigenous Arctic peoples seem to be close to the global maximum of cognitive ability, but the evidence is limited and questionable. This situation has three causes:

 

·         Difficulties in administering IQ tests to people who are unfamiliar not only with modern concepts but also with the modern question-and-answer paradigm. Traditionally, indigenous Arctic people learn not by asking questions but by observing a “master” and then copying whatever he or she does. Asking questions can also be impolite, especially if too many are asked in rapid succession. I should point out that the same difficulties used to exist in Western societies. People in Britain and North America were unfamiliar with standardized written tests until the rise of publicly funded schools and competitive civil-service exams in the late 19th century (Wikipedia 2022). It wasn’t because people got smarter that mean IQ rose during the 20th century. They just got better at taking tests.

 

·         Ideological constraints. IQ research was discouraged in the Soviet Union, partly because of the dominant belief in environmental determinism and partly because of a desire to avoid stigmatizing certain national groups. A ban on intelligence testing was thus imposed in 1936 and gradually lifted only in the 1960s and early 1970s (Grigoriev and Lynn 2009).

 

·         Lack of research on alleles associated with educational attainment. This avenue of research offers a better measure of innate cognitive ability but is still in its infancy with respect to Arctic peoples. I know of only one relevant study. Piffer (2013) found that the Met allele at COMT, a gene linked to executive function, working memory, and intelligence, is more frequent in farming societies than in hunter-gatherers, with one interesting exception: "hunter-gatherers living at high latitudes (Inuit) show high frequencies of the Met allele, possibly due to the higher pressure on technological skills and planning abilities posed by the adverse climatic conditions near the North Pole."

 

 

Siberia (Evenk, Altai, Yakuts)

 

In Siberia, IQ tests were conducted in 1929 and later in 2015-17. The first period saw testing among the Evenk of the northeast and the Altai of the south.

 

When a Binet test was administered to 5 Evenk children 7 to 19 years old, the mean score was 70.16. The study’s author reported that the children had trouble understanding units of measurement and number.

 

He reported that when Evenk children were questioned about devices for measurement, they did not have the concept of an absolute unit of measurement. They thought that the unit changed with the material measured. Bulanow [the author] reported further that when he asked Evenk adults how many children they had “It was difficult, almost impossible, to get from parents precise information as to how many of their children were alive, how many of their children had died, what was the age of their children, and so on.” (Grigoriev and Lynn 2009, p. 449)

 

When a Binet test was administered to 52 Altai children 8 to 20 years old, the mean score was 66.9. Again, the subjects had problems with units of measurement: “when they were questioned about the length of a meter, the Altai would often ask: “Which meter?” They thought that the meter in one shop could be longer than in another” (Grigoriev and Lynn 2009, p. 450). Nonetheless, adult Altai showed remarkable aptitudes in other areas of life:

 

Although adult Altai performed calculations poorly at the time of study, they showed a remarkable ability for visual estimation of large quantities. A herdsman, who could count only to 20–30, noticed very well the absence of one horse, cow or sheep in a herd of many hundreds. He looked at a huge herd and noted that a particular cow was absent. Another example of the great visualization ability of the Altai was that they could remember and showed the way through wild territory, where they had been only once many years previously (Grigoriev and Lynn 2009, p. 450)

 

In recent years, there has been a renewed effort to study cognitive ability among indigenous Siberian peoples:

 

·         Shibaev and Lynn (2015) tested 29 Evenk children and found a mean score of 80. Also tested were 13 ethnic Russian children, who had grown up under similar conditions. Their mean score was 85.

·         Shibaev and Lynn (2017) tested 287 Yakut children and 52 ethnic Russian children from eastern Siberia. The mean score was 97.0 for the Yakuts and 97.9 for the ethnic Russians.

·         Shibaev et al. (2020) tested 518 Yakut children and 956 ethnic Russian children. The age range was wider than in previous studies, and the IQ difference between the two groups seemed, in general, to be greater at younger ages than at older ones. At 9 years of age the Russians had a 3 point advantage over the Yakuts, whereas at 17 this advantage was zero. Yakut children may have a slower rate of cognitive maturation. There is also some doubt as to the comparability of the two groups, since the Russians came largely from a city (Tomsk), while the Yakuts came from a city (Yakutsk) and a small town (Vilyuysk).

 

The authors note that the differences between ethnic Russians and indigenous Siberians can be largely explained by an urban-rural divide:

 

[…] for both Russians and Yakuts the IQs of the city samples were higher than the IQs of the village samples. For the Russians, there was a difference of 10.5 IQ points between the combined city samples and the village sample, while for the Yakuts the difference was 4.4 points. The higher IQs of the city samples is a common result found in many previous studies reporting that urban populations typically obtain higher IQs than rural populations. (Shibaev and Lynn 2017)

 

Shibaev and Lynn (2017) attribute this urban-rural divide to differential migration: smarter people move to the city, and dumber people stay home in the village. I would argue that villagers are less familiar with modern concepts and the modern question-and-answer paradigm.

 

Arctic North America (Inuit)

 

Like indigenous Siberians, the Inuit (Eskimos) display an unusual ability to find their way across vast expanses of territory, a task that requires remembering huge amounts of visuospatial data. Adults are reported to have an "extraordinary ability to find their way through what appears to be a featureless terrain by remembering visual configurations [...]. According to some reports, such memories persist for long periods of time. Elderly hunters have succeeded in guiding parties through terrain seen only in their youth" (Kleinfeld 1973, p. 344)

 

Nonetheless, Inuit have done poorly in most IQ studies, especially in older studies of traditional Inuit. Kleinfeld (1973) cites several reasons:

 

Unfamiliarity with test-taking:

Eskimos' performance on standardized tests may be lowered because of their unfamiliarity with test-taking conventions and because of cultural biases of the tests. Eskimos, for example, may find it difficult to view a trivial, pointless task such as copying a design or running through a finger maze as worthy of serious concentration and maximum effort.

 

Racial context of test-taking

Eskimos, especially young males, have become increasingly antagonistic to any sort of testing and research, which they view as another form of White exploitation. Co-operation, if given at all, may be perfunctory, resulting in extremely low test scores.

 

Extreme caution during test-taking

Eskimos, especially males, have been socialized into extreme caution before making a judgment. The hunter is taught never to take risks, never to call out a hasty evaluation because the penalty can be swift death not only for himself but also for others who rely on his decision. […] Especially more traditional Eskimos tend to have a slow, cautious response style which may depress their scores on speeded figural tests.

 

Slower rate of cognitive maturation

[There is] some evidence that Eskimos' peak performance on figural tests occurs later than that of Western groups. [This] raises the possibility of a slower rate of cognitive maturation among Eskimos which would be consistent with their somewhat slower rate of physical maturation […]. If this is the case, the usual age-matched comparisons between Western and Eskimo children on figural tests may be misleading.

 

In their reviews of the literature, Kleinfeld (1973) and Taylor and Skanes (1976) note that Inuit generally outperform Whites on visual discrimination and spatial tests. Interestingly, Inuit children do almost as well as non-Inuit children on English spelling tests while doing poorly in other aspects of English, perhaps because they memorize the shapes of words. On the other hand, they underperform White children on verbal-educational and inductive reasoning tests. The latter finding may reflect lack of familiarity with English in earlier studies. When Taylor and Skanes (1976a) tested Inuit and White first graders for vocabulary and arithmetic, using the Wechsler Pre-School and Primary Scale of Intelligence, they found no significant differences between the two groups in spatial, verbal-educational, and inductive reasoning abilities. When the same researchers tested a larger sample of Inuit and White children from different age groups, using a series of digit span tests and Raven’s progressive matrices, they found that the Inuit children caught up with the White children with increasing age on the digit span tests and that the Inuit children outperformed the White children on the Raven’s progressive matrices (Taylor and Skanes 1976b).

 

Wright et al. (1996) tested the IQ of Inuit children in Arctic Quebec during the first two grades of school, using Coloured Progressive Matrices (CPM). Mean scores were consistently higher than age-appropriate U.S. norms and were comparable with data for White children in southern Quebec. In addition, the scores of children with two Inuit parents did not differ significantly from those of children with mixed Inuit/White heritage. 

 

Nonetheless, Inuit children do worse at school than other children, having not only lower rates of academic achievement but also higher dropout and suicide rates. For Clifton and Roberts (1988), the reason is inferior self-perception of their ability and less active involvement in the educational process. This mindset may be rooted in the traditional Inuit attitude toward education, where the “student” simply observes and copies the “master.”

 

In sum, the Inuit seem to have about the same level of cognitive ability as people of European origin, with perhaps some interesting differences: superior visuospatial skills, higher risk aversion, slower cognitive maturation, and a more imitative and less inquisitive approach to learning. It is still unclear whether they have lower verbal-educational and inductive reasoning abilities. In their review, McShane and Berry (1988, p. 392) conclude that indigenous Arctic peoples do well relative to Euroamerican norms, showing “high performance on both piagetian and psychometric tests of visually based spatial, analytic, disembedding, and inductive abilities.” The two researchers attribute reports of lower verbal ability to second-language familiarity with the test language. Clearly, more research is needed, if only to adapt the northern educational system to Inuit needs.

 

It must be said that the Inuit are ill-suited to the Western model of education and, more broadly, to the Western model of sedentism, individualism, and asociality. Young Inuit feel useless in that kind of society, and all too many end up committing suicide.

 

Conclusion and discussion

 

We have only a few studies of cognitive ability among indigenous Arctic peoples. This paucity is due only in part to methodological problems. In the Soviet Union, all IQ research ceased between 1936 and the 1960s. It has recommenced among indigenous Arctic peoples only over the past decade. Meanwhile, similar research in Canada and the U.S. has been nonexistent since the 1990s.

 

If we look at the existing research, we may doubt whether the subjects were fully familiar with test-taking and the modern question-and-answer paradigm. Another problem is that indigenous Arctic children seem to have a slower rate of cognitive maturation. If Yakut subjects are still catching up to Russian subjects at the age of 17, it might be more appropriate to compare the two groups at an older age. In practice, this would be difficult because young adults start following different life paths after 17. Finally, indigenous Arctic peoples may allocate their mental capacities differently, being better, for instance, at processing visuospatial data than other kinds of information. Since IQ tests have been designed for Western children, the test design may not correspond to the mental tasks that some non-Western groups prioritize.

 

Yes, dear reader, I hear you. If people do well on one cognitive task, they should do well on all others, shouldn’t they? Isn’t that what the g factor is all about? In other words, people will tap into the same mental capacity for any cognitive task.

 

The relative strength of the g factor, however, has been calculated from subjects in Western or Westernized societies. Does it have the same strength across different mental domains among people who until recently were nomadic hunters? Anthropologists, like John Berry, have argued that hunters allocate much more of their mental capacity to visuospatial orientation:

 

Hunters, by this way of thinking, require good visual acuity, keen disembedding skills and a well-developed sense of spatial orientation. To hunt successfully, the hunter must be able to discern the object of the quest (which is often embedded in a complex visual landscape), then disembed the object, and finally return to home base. In contrast, agriculturalists need not develop these particular skills, but rather they need to invest in other areas of development, such as conservation (in both the economic and the Piagetian senses) and close social interactions. (Berry 2008, p. 3)

 

It would be interesting to find out whether these skills have become hardwired to some degree through gene-culture coevolution. Are hunting peoples inherently better at orienting themselves in space? Did vast expanses of land favor the success of people who could more easily find their way across vast expanses of land? To answer that question, John Berry launched a project in the late 1980s with the geneticist L.L. Cavalli-Sforza. They wished to recruit participants among the Inuit of northern Canada and use aptitude for soapstone carving as a means to measure visuospatial skills:

 

With most individuals having had a reasonably fair chance and stimulation to become artists, one is in a better condition to study possible genetic factors contributing to artistic talent, if any. Another great advantage of carrying out this study among the Inuit is the frequency with which adoptions (also early ones, at birth) occur in this population. Frequencies of adoptions reported during the meeting varied from 15% to 30%. Adoptions allow one to distinguish cultural from biological inheritance by studying correlations of adopted children with foster relatives on one hand and biological relatives on the other. (Berry and Cavalli-Sforza 1986)

 

Cavalli-Sforza was thinking, here, along the lines of gene-culture coevolution. He had in fact been one of the founders of that paradigm, although he preferred the term “dual inheritance theory.” Now, he would have a chance to investigate it in the field.

 

Then, suddenly, he backed out of the project. For “health reasons.” Yet neither his biography nor his autobiography mentions any health problems during that period of his life.

 

 

References

 

Berry, J.W. (2008). Models of Ecocultural Adaptation and Cultural Transmission: The Example of Inuit Art, paper presented at the conference Adaptation et socialisation des minoritiés culturelles en région, June 3-4, Quebec City.

 

Berry, J.W., and L.L. Cavalli-Sforza. (1986). Cultural and Genetic Influences on Inuit Art. Report to the Social Sciences and Humanities Research Council of Canada, Ottawa.

 

Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World. Princeton University Press, Princeton and Oxford

 

Clifton, R.A. and L.W. Roberts. (1988). Social psychological dispositions and academic achievement of Inuit and non-Inuit students. Alberta Journal of Educational Research 34(4): 332–343.

 

Cochran, G., J. Hardy, and H. Harpending. (2006). Natural history of Ashkenazi intelligence. Journal of Biosocial Science 38(5): 659–693. https://doi.org/10.1017/S0021932005027069

 

Dunkel, C.S., M.A. Woodley of Menie, J. Pallesen, and E.O.W. Kirkegaard.  (2019). Polygenic scores mediate the Jewish phenotypic advantage in educational attainment and cognitive ability compared with Catholics and Lutherans. Evolutionary Behavioral Sciences 13(4): 366-375.  https://psycnet.apa.org/doi/10.1037/ebs0000158

 

Frost, P. (2007). Natural selection in proto-industrial Europe. Evo and Proud, November 16

http://evoandproud.blogspot.com/2007/11/natural-selection-in-proto-industrial.html  

 

Frost, P. (2019). The Original Industrial Revolution. Did Cold Winters Select for Cognitive Ability? Psych 1(1): 166-18. https://doi.org/10.3390/psych1010012  

 

Grigoriev, A, and R. Lynn. (2009). Studies of socioeconomic and ethnic differences in intelligence in the former Soviet Union in the early twentieth century. Intelligence 37: 447-452, https://doi.org/10.1016/j.intell.2009.05.005  

 

Kleinfeld, J.S. (1973). Intellectual Strengths in Culturally Different Groups: An Eskimo Illustration. Review of Educational Research 43(3): 341-359.

https://doi.org/10.3102%2F00346543043003341  

 

McShane, D., and J.W. Berry. (1988). “Native North Americans: Indian and Inuit Abilities.” In: S.H. Irvine and J.W. Berry (eds.) Human Abilities in Cultural Context (pp. 385-426), Cambridge: Cambridge University Press.

 

Piffer, D. (2013). Correlation of the COMT Val158Met polymorphism with latitude and a hunter-gather lifestyle suggests culture-gene coevolution and selective pressure on cognition genes due to climate. Anthropological Science 121(3): 161-171. https://doi.org/10.1537/ase.130731  

 

Piffer, D. (2019). Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from Gwas Hits: A Replication of Previous Findings Using Recent Data. Psych 1(1): 55-75. https://doi.org/10.3390/psych1010005    

 

Seccombe, W. (1992). A Millennium of Family Change. Feudalism to Capitalism in Northwestern Europe. London: Verso.

 

Shibaev, V., A. Grigoriev, E. Valueva, and A. Karlin. (2020). Differential Item Functioning on Raven’s SPM+ Amongst Two Convenience Samples of Yakuts and Russians. Psych 2(1):44-51. https://doi.org/10.3390/psych2010005

 

Shibaev, V. and R. Lynn. (2015). The Intelligence of the Evenk/Tungus of the Russian Far East. Mankind Quarterly 56(2): 202-207. http://doi.org/10.46469/mq.2015.56.2.7  

 

Shibaev, V. and R. Lynn. (2017). The Intelligence of Yakuts and Ethnic Russians in Yakutia. Mankind Quarterly 57(4): 680-686. http://doi.org/10.46469/mq.2017.57.4.11  

 

Taylor, L.J., and G.R. Skanes. (1976a). Cognitive abilities in Inuit and White children from similar environments. Canadian Journal of Behavioural Science 8(1): 1-8.

https://psycnet.apa.org/doi/10.1037/h0081930  

 

Taylor, L.J., and G.R. Skanes. (1976b). Level I and level II intelligence in Inuit and White children from Similar Environments. Journal of Cross-Cultural Psychology 7(2): 157-168.

https://doi.org/10.1177%2F002202217672004

 

Unz, R. (2013). How Social Darwinism made modern China, The American Conservative, March/April, 16-27. https://www.theamericanconservative.com/articles/how-social-darwinism-made-modern-china-248/  

 

Wikipedia (2022). Test (assessment). https://en.wikipedia.org/wiki/Test_(assessment)#West  

 

Woodley, M.A., S. Younuskunju, B. Balan, and D. Piffer. (2017). Holocene selection for variants associated with general cognitive ability: comparing ancient and modern genomes. Twin Research and Human Genetics 20: 271-280. https://doi.org/10.1017/thg.2017.37   

 

Wright, S.C., D.M. Taylor, and K.M. Ruggiero. (1996). Examining the Potential for Academic Achievement among Inuit Children: Comparisons on the Raven Coloured Progressive Matrices. Journal of Cross-Cultural Psychology 27(6): 733-753.

https://doi.org/10.1177%2F0022022196276006  

Rice farming and gene-culture coevolution

 

Why didn’t alcohol intolerance evolve the same way in China as it did in southern Europe? One reason was that the Chinese have a long tradition of boiling water for drinking. So they didn’t need wine as a safe, pathogen-free alternative to water. Facial flushing, before and after (Wikicommons, Brooks et al. 2009)

 

 

In a study of 1,162 Han Chinese, a team led by Thomas Talhelm (2014) found certain psychological differences between Chinese from rice-farming regions and those from wheat-farming regions. The latter tended to be more individualistic, more analytic in their thinking, and less likely to make a big distinction between friends and strangers. Interestingly, these findings were no less true for subjects who had no connection to farming of either sort.

 

Talhelm et al. (2014) attributed these psychological differences to differences between rice farming and wheat farming:

 

The two biggest differences between farming rice and wheat are irrigation and labor. Because rice paddies need standing water, people in rice regions build elaborate irrigation systems that require farmers to cooperate. In irrigation networks, one family's water use can affect their neighbors, so rice farmers have to coordinate their water use. Irrigation networks also require many hours each year to build, dredge, and drain—a burden that often falls on villages, not isolated individuals. 

 

In comparison, wheat is easier to grow. Wheat does not need to be irrigated, so wheat farmers can rely on rainfall, which they do not coordinate with their neighbors. Planting and harvesting wheat certainly takes work, but only half as much as rice. The lighter burden means farmers can look after their own plots without relying as much on their neighbors. (Talhelm et al., 2014)

 

The term “gene-culture coevolution” isn’t mentioned, but it did cross my mind when I read that paper, and I suspect it also crossed Talhelm’s. Did rice farming favor the success of individuals who were better at rice farming? And were those individuals sometimes better because they had certain mental and behavioral tendencies?

 

That hypothesis has recently been tested in a study by Chen Zhu and other co-researchers, including Thomas Talhelm:

 

Here, we report evidence that the advent of rice domestication and cultivation may have shaped humans not only culturally but also genetically. Leveraging recent findings from molecular genetics, we construct a number of polygenic scores (PGSs) of behavioural traits and examine their associations with rice cultivation based on a sample of 4101 individuals recently collected from mainland China. (Zhu et al. 2021)

 

The polygenic scores were for height, body mass index, depression, time discounting, age at first birth, educational attainment, risk preference, and tolerance for alcohol (as measured by the ability to break it down via two enzymes: alcohol dehydrogenase and aldehyde dehydrogenase). For each mental or behavioral trait, the polygenic scores were compared with the subjects’ county of birth, specifically the county’s proportion of farmland devoted to rice paddies.

 

The trait/county correlations were then investigated for possible confounds. Because rice farming is more common in southern China, there may be confounds with latitude, temperature, certain minority groups, and so on. After controlling for these confounds, the authors found that two negative correlations remained significant: (1) age at first birth and (2) tolerance for alcohol, as measured by the ability to produce aldehyde dehydrogenase.

 

It seems, then, that people from rice-farming regions are more likely to feel sick after drinking alcohol, and that women are more likely to begin having children at a younger age. Let’s take a closer look at both findings:

 

Age at first birth

 

Rice-farming regions are associated with a younger age at first birth. Historically, rice was far more labor-intensive than wheat. The labor demands were so high that a husband and wife could not farm a large enough plot to support their family through their labor alone. Life expectancy may have also been shorter in rice-farming regions than in wheat-farming ones, with the result that the reproductive schedule was shifted toward younger ages wherever rice was primarily grown (Zhu et al. 2021). 

 

Alcohol tolerance

 

Rice-farming regions are associated with defective enzymes for alcohol tolerance. This seems to be much truer for aldehyde dehydrogenase than for alcohol dehydrogenase. Both defects reduce clearance of alcohol by the liver, but the first one has a stronger effect. In about 36% of East Asians, it causes facial flushing, nausea, and tachycardia after alcohol consumption. Not surprisingly, carriers appear to suffer less from alcoholism and alcohol-related liver disease (Brooks et al. 2009; SNPedia 2020).

 

Zhu et al. (2021) argue that selection against alcohol tolerance was stronger in rice-farming regions because rice farmers had surplus rice for wine production at an earlier date. This argument assumes that alcohol consumption was always maladaptive: once it became common, selection immediately favored individuals who couldn’t tolerate alcohol. Yet we know that alcohol consumption used to be adaptive in many parts of the world, such as southern Europe, where fermented beverages were safer to drink than water because they had no water-borne pathogens.

 

I would argue that selection against alcohol tolerance began in China when fermented beverages, notably rice wine, ceased to be the best alternative to water. Consumption of rice wine was widespread at first but later gave way to consumption of boiled water, particularly in the form of tea, during the Tang dynasty (7th to 10th centuries). There then followed a period of relative abstinence until the 19th century:

 

Following the Yangtze's incorporation into the Chinese state during the Qin dynasty, beer progressively disappeared from use over the course of the Han dynasty in favor of the stronger huangjiu and the rice wines of the southern Chinese. […] The Dutch historian Frank Dikötter describes the period between the Han and Tang dynasties as a "golden age" for alcohol […] The "rise of a tea culture during the Tang was a significant shift away from heavier patterns of intoxication".  […] Wine was reintroduced to China at Macao by Portuguese traders and missionaries, who produced small batches for communion. […] The production and its effect was minor, prior to the opening of the country by the 19th-century First and Second Opium Wars, after which European alcoholic beverages and methods of alcohol production were introduced throughout China. (Wikipedia 2022)

 

With the replacement of rice wine by tea during the Tang Dynasty, people no longer had the same need for enzymes that break down alcohol. The advantages of alcohol, in terms of preventing water-borne diseases, became outweighed by the disadvantages, in terms of alcoholism and alcohol-related diseases.

 

Thus began a long Chinese tradition of drinking hot water (Ye 2017). Rice wine, with its high alcohol content of 18-25%, became seen not only as unnecessary but also as problematic, due to the risk of alcoholism and alcohol-related diseases. Rice-farming regions may have therefore experienced a steeper decline in alcohol consumption during China’s long period of relative abstinence between the 7th and 19th centuries. If so, alcohol intolerance would be a recent evolutionary development in China’s rice-farming regions.

 

Elsewhere, as in southern Europe, people continued to drink wine as a safe alternative to water. There was thus selection for willingness to consume alcohol, but not to excess.

 

What about individualism?

 

Why didn’t Zhu’s research team look at genetic markers for individualism? Wasn’t that the main behavioral difference between rice-farming and wheat-farming regions in Talhelm’s study? The oversight is all the more puzzling because Talhelm was one of Zhu’s co-authors.

 

There is, in fact, a genetic marker for individualism: the short allele of 5-HTTLPR (Chiao and Blizinsky 2010; Schroeder et al., 2016). In addition, I would look at genetic markers for the propensity to identify social norms, to comply with them, and to ensure that others comply (Frost 2020).

 

What about cognitive ability and future orientation?

 

Zhu et al. (2021) also looked at cognitive ability (as measured by educational attainment) and future orientation (as measured, inversely, by time discounting). Cognitive ability and future orientation are both high in East Asians, but neither seem to differ significantly between Chinese from rice-farming regions and those from wheat-farming regions. In the initial results (i.e., before they were controlled for possible confounds), the first group was less future-oriented than the second, but this difference seems to be due to southern Chinese being less future-oriented than northern Chinese.

 

Things are rarely simple. No single theory can explain all the mental and behavioral differences that exist within our species. Yes, some researchers have proposed various unified theories of human biodiversity: r/k selection, selection in tropical vs. northern environments, and selection among trading vs. non-trading peoples, etc.  Each of them explains part of the picture, but none explains the whole picture.

 

There will never be a unified theory of human biodiversity, other than Darwin’s theory of evolution by natural selection. Human nature is shaped by many different selection pressures with many different causes.

 

References

 

Brooks, P.J., M-A. Enoch, D. Goldman, T-K Li, and A. Yokoyama. (2009). The Alcohol Flushing Response: An Unrecognized Risk Factor for Esophageal Cancer from Alcohol Consumption. PLoS Med 6(3): e1000050. https://doi.org/10.1371/journal.pmed.1000050  

 

Chiao, J. Y., & K.D. Blizinsky. (2010). Culture-gene coevolution of individualism-collectivism and the serotonin transporter gene. Proceedings of the Royal Society B: Biological Sciences 277: 529-537. https://doi.org/10.1098/rspb.2009.1650   

 

Frost, P. (2014). Rice farming and gene-culture co-evolution. Evo and Proud, May 31

https://evoandproud.blogspot.com/2014/05/   

 

Frost, P. (2020). The large society problem in Northwest Europe and East Asia. Advances in Anthropology 10(3): 214-134.

https://doi.org/10.4236/aa.2020.103012    

 

SNPedia (2020). rs671

https://www.snpedia.com/index.php/Rs671   

 

Talhelm, T., X. Zhang, S. Oishi, C. Shimin, D. Duan, X. Lan, and S. Kitayama. (2014). Large-scale psychological differences within China explained by rice versus wheat agriculture. Science 344: 603-607.

https://doi.org/10.1126/science.1246850   

 

Wikipedia (2022). Alcoholic drinks in China.

https://en.wikipedia.org/wiki/Alcoholic_drinks_in_China

 

Ye, F. (2017). The History of Drinking Hot Water in China (from a Cold-Water-Drinking Chinese). Radii, June 23

https://radiichina.com/the-history-of-drinking-hot-water-in-china/   

 

Zhu, C., T. Talhelm, Y. Li, G. Chen, J. Zhu, and J. Wang. (2021). Relationship between rice farming and polygenic scores potentially linked to agriculture in China. Royal Society Open Science 8(8):210382. https://dx.doi.org/10.1098%2Frsos.210382   

Vitamin D scarcity and natural selection

 

In humans who are dark-skinned or who live above the Arctic Circle, natural selection has favored those who use vitamin D more efficiently or have workarounds of one sort or another for vitamin D scarcity. Yakut family, Wikicommons (Uyban)

 

 

Vitamin D is less easily obtained by some people than by others. It is less available to those who are dark-skinned or who live above the Arctic Circle. Because less UV light enters the skin for biosynthesis, natural selection has favored individuals who use this vitamin more efficiently or have workarounds of one sort or another (Frost 2009; Frost 2012; Frost 2018).

 

Vitamin D levels are thus naturally lower in Arctic and dark-skinned humans. Some variation exists even among Europeans, with levels being lower in darker-skinned southern Europeans than in lighter-skinned northern Europeans (Snellman et al. 2009; van der Wielen et al. 1995).

 

Unfortunately, vitamin D deficiency is diagnosed on the basis of norms developed for light-skinned people from temperate latitudes. Inuit and African Americans are thus diagnosed as “deficient” and offered vitamin supplementation, which has the effect of bathing their body tissues in concentrations of vitamin D that they and their ancestors have not experienced for tens of thousands of years, if not longer.

 

If  Arctic and darker-skinned humans naturally have lower levels of vitamin D, their optimal range of levels will likewise be lower, and toxic effects may occur at levels that lie within the optimal range of Europeans. You may have been told that this cannot happen because toxicity occurs only if you ingest huge amounts of this vitamin. Actually, toxicity begins at relatively low levels. In light-skinned humans from the temperate zone, the optimal range seems to extend only from 40 nmol/L to 100 nmol/L:

 

·         The total mortality rate is about 50% greater in men whose vitamin D levels are either below 46 nmol/L or above 98 nmol/L (Michaelsson et al. 2010).

·         The risk of prostate cancer is significantly greater below 40 nmol/L and above 60 nmol/L (Tuohimaa 2008; Tuohimaa et al. 2009).

·         Mortality for 7 types of cancer (endometrial, esophageal, gastric, kidney, non-Hodgkin's lymphoma, pancreatic, ovarian) is significantly greater below 45 nmol/L and above 124 nmol/L (Helzlsouer et al. 2010).

·         The risk of pancreatic cancer is significantly greater above 100 nmol/L (Stolzenberg-Solomon et al. 2010).

·         The risk of cardiovascular disease is significantly greater below 50 nmol/L and above 62.5 nmol/L, and mortality from all causes is significantly greater above 122.5 nmol/L (Davis 2009).

 

Perhaps most worrisome, studies on mice indicate a U-shaped response curve for the aging process, with premature aging associated with both too little and too much vitamin D (Tuohimaa 2009; Tuohimaa et al. 2009).

 

Vitamin D metabolism and gene-culture coevolution among the Inuit

 

To what extent has the safe range of vitamin D been shifted downward in Arctic and dark-skinned humans? To answer that question, we need to understand gene-culture coevolution. When humans enter a new environment, they adapt by pushing the bounds of phenotypic plasticity—they do the most with what they have already. There is then natural selection for genetic variants that can stabilize this new pattern of adaptation and make it more innate. A new phenotype thus ends up becoming a new genotype.

 

Traditionally, Inuit coped with vitamin D scarcity through a high-meat/low-cereal diet and through extended breastfeeding of children for two years or longer. This diet not only provided vitamin D but also helped the body use this vitamin more efficiently, specifically by means of β-casein in breast milk, unknown substances in meat, and absence of phytic acid (Frost 2018). 

 

Those cultural adaptations were followed by physiological adaptations: receptors that bind more tightly to the vitamin D molecule; a lower set-point for calcium-regulated release of parathyroid hormone; and conversion of vitamin D at a higher rate from its common form to its most active form. Inuit breast milk might also be richer in β-casein (Frost 2018).

 

That gene-culture coevolution has been notably demonstrated by a genome study of the Greenland Inuit, whose marine diet has apparently selected for genetic variants that help their bodies digest and use polyunsaturated fatty acids (Fumagalli et al. 2015).

 

Research on indigenous northern Eurasian peoples

 

Before 2020, the Inuit were the only non-European population for whom we had research on cultural and physiological adaptations to vitamin D scarcity (Frost 2012; Frost 2018). Two studies have since been published on this subject with regard to indigenous peoples in northern Eurasia.

 

Research by Khrunin et al. (2020)

 

This research team looked for signals of natural selection in the genomes of eight northern populations: Russians from the Archangelsk and Vologda regions; Izhemski Komi; Priluzski Komi; Veps; Khanty; Mansi; and Nenets. The strongest signal came from two genes: SLC37A2 and PKNOX2. The first gene is expressed when vitamin D₃ is present in peripheral blood cells. The authors go on to note:

 

Deficit of vitamin D is often observed in northern populations, where exposure to sunlight is limited for many months. Hypothetically, mutations in the VDR-controlled SLC37A2 gene may help northern populations adjust to vitamin D levels. At the same time, the same mutations could have effects on alcohol tolerance in these populations through the PKNOX2 gene, located on the opposite strand of DNA in the same locus. 

 

The second gene, PKNOX2, is associated with alcohol addiction in mice and humans. The authors add that this finding “is of special interest in the context of the well-known alcohol addiction that occurs widely in indigenous populations of Northern Eurasia.”

 

Could vulnerability to alcoholism be a side-effect of adaptation to vitamin D scarcity? The hypothesis is interesting, although I lean more toward another explanation. Some populations, like those around the Mediterranean, have had a long history of drinking fermented beverages instead of water, which might be contaminated with bacteria that cause dysentery and other diseases. Consequently, natural selection has favored individuals who have higher levels of alcohol dehydrogenase and other physiological adaptations that make alcohol less toxic. Conversely, other populations, like northern Eurasians, have consumed fermented beverages for a shorter time, and their bodies are less adapted to alcohol (Nabhan 2004, pp. 27-30; Ridley 2000).

 

Research by Malyarchuk (2020)

 

This is a study of a single polymorphic gene, GC, in several indigenous peoples of northeastern Siberia (Eskimos, Chukchi, Koryaks), central Siberia (Evens, Evenks, Yakuts), southern Siberia (Tuvinians, Shorts, Altaians, Buryats), and western Siberia (Kets, Khanty, Mansi, Selkups, Nenets, Nganasans). The GC gene produces a protein that is the main carrier of vitamin D in the body.

 

One GC variant, specifically the T variant at rs4588, is much less frequent in northeast and central Siberians (5.4%, 3.1%) than in southern and western Siberians (28.6%, 27.5%). Conversely, the G variant is much more frequent in the northeast and center (32.1%, 46.9%) than in the south and west (16.1%, 12.5%). I initially thought the reason was a higher level of European admixture in southern and western Siberia. But there is little European admixture in East Asians, and they resemble southern and western Siberians in having the same high frequency of the T variant (26.1%).

 

The G variant may have become more frequent in northeast and central Siberians as an adaptation to vitamin D scarcity. As one goes farther north, the skin produces less vitamin D because less UV light enters the skin. More research is needed, however, on two other factors: (1) amount of vitamin D from dietary sources; and (2) skin pigmentation. It may be that southern Siberians are somewhat darker-skinned than northern Siberians, although that isn’t my impression. These points are made by Malyarchuk (2020) in the Results and Discussion section. Researchers should study:

 

… the gene-environment interactions by taking into account the vitamin D status of the indigenous population, ethnicity, influence of environmental conditions (the level of natural ambient light and seasonal patterns), and specifics of nutrition. The influence of such factors on the distribution of GC polymorphism variants is evidenced by the data obtained in this work on the high prevalence of haplotypes encoding the Gc1F isoform in northeast Asia under condition of low intensity of solar radiation. In addition, an important factor contributing to vitamin D deficiency may be a relatively high level of melanin in the skin of representatives of the Arctic peoples, which prevents the penetration of ultraviolet rays into the skin and thereby hinders the synthesis of vitamin D₃

 

References

 

Davis, C.D. (2009). Vitamin D and health: can too much be harmful? American Journal of Lifestyle Medicine 3(5): 407-408. https://doi.org/10.1177/1559827609338154

 

Frost, P. (2009). Black-White differences in cancer risk and the vitamin-D hypothesis. Journal of the National Medical Association 101: 1310-1313.

https://doi.org/10.1016/s0027-9684(15)31151-2

 

Frost, P. (2012). Vitamin D deficiency among northern Native Peoples: a real or apparent problem? International Journal of Circumpolar Health 71(S2): 18001

https://doi.org/10.3402/IJCH.v71i0.18001

 

Frost, P. (2018). To supplement or not to supplement: are Inuit getting enough vitamin D? Études Inuit Studies 40(2): 271-291.

https://doi.org/10.7202/1055442ar

 

Frost, P. (2020). Ethnic differences in vitamin-D metabolism. E Scholarly Community Encyclopedia.

https://encyclopedia.pub/3033

 

Fumagalli, M., I. Moltke, N. Grarup, F. Racimo, P. Bjerregaard, M.E. Jørgensen et al. (2015). Greenlandic Inuit show genetic signatures of diet and climate adaptation. Science 349(6254): 1343-1347. https://doi.org/10.1126/science.aab2319

 

Helzlsouer, K.J. and Steering Committee of Vitamin D Pooling Project of Rarer Cancers (2010).  Abstract PL04-05: Vitamin D: panacea or a Pandora’s box for prevention? Cancer Prevention Research 3(1 Suppl 1): PL04-05. https://doi.org/10.1158/1940-6207.PREV-09-PL04-05

 

Khrunin, A.V., G.V. Khvorykh, A.N. Fedorov, and S.A. Limborska (2020). Genomic landscape of the signals of positive natural selection in populations of Northern Eurasia: A view from Northern Russia. PLoS ONE 15(2): e0228778. https://doi.org/10.1371/journal.pone.0228778

 

Malyarchuk, B.A. (2020). Polymorphism of GC gene, encoding vitamin D binding protein, in aboriginal populations of Siberia. Ecological Genetics 18(2): 243-250.

https://doi.org/10.17816/ecogen18634

 

Michaëlsson, K., J.A. Baron, G. Snellman, R. Gedeborg, L. Byberg, J. Sundström et al. (2010). Plasma vitamin D and mortality in older men: a community-based prospective cohort study. American Journal of Clinical Nutrition 92(4): 841-848. https://doi.org/10.3945/ajcn.2010.29749 

 

Nabhan, G.P. (2004). Why Some Like It Hot. Food, Genes, and Cultural Diversity. Washington: Island Press/Shearwater Books.

 

Ridley, M. (2000).Genome: The Autobiography of a Species in 23 Chapters. New York: HarperCollins.

 

Snellman, G., H. Melhus, R. Gedeborg, et al. (2009). Seasonal genetic influence on serum 25-hydroxyvitamin D levels: a twin study. PLoS ONE 4(11): e7747. https://doi.org/10.1371/journal.pone.0007747

 

Stolzenberg-Solomon, R.Z., E.J. Jacobs, A.A. Arslan, D. Qi, A.V. Patel, K.J. Helzlsouer et al.

(2010). Circulating 25-hydroxyvitamin D and risk of pancreatic cancer, Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. American Journal of Epidemiology 172(1): 81-93.

https://doi.org/10.1093/aje/kwq120

 

Tuohimaa, P. (2009). Vitamin D and aging. The Journal of Steroid Biochemistry and Molecular Biology 114(1-2): 78-84. https://doi.org/10.1016/j.jsbmb.2008.12.020 

 

Tuohimaa, P., T. Keisala, A. Minasyan, J. Cachat, and A Kalueff (2009). Vitamin D, nervous system and aging. Psychoneuroendocrinology 34S: S278-286. https://doi.org/10.1016/j.psyneuen.2009.07.003

 

van der Wielen R.P., M.R. Lowik, H. van den Berg, L.C. de Groot, J. Haller J, et al. (1995). Serum vitamin D concentrations among elderly people in Europe. Lancet 346: 207–210. https://doi.org/10.1016/S0140-6736(95)91266-5