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   

American Indians in decline

 

After three decades of sharp decline, American Indians now have the lowest fertility rate of all ethnic groups in the U.S. The trend is real and is not due to sub-fertile Whites self-identifying as American Indians.

 

 

The pandemic has reduced the American birth rate. According to data from 2020 and early 2021, almost all ethnic groups have taken a hit, but the magnitude has been greater for some than for others.

 

Asian Americans took the biggest hit. At first thought, this makes sense. Asians, especially East Asians (who make up a majority of Asian Americans) tend to take infectious diseases more seriously. They are generally more willing to wear masks, practice social distancing, and wash their hands, and it seems logical that they would also be more willing to postpone childbearing.

But that's not the whole story. The pandemic has accelerated an ongoing fertility decline among East Asians at home and abroad. With the exception of North Korea, East Asia was already a zone of ultra-low fertility—about one child per woman. When the pandemic is over, I predict that East Asian fertility will not return to pre-pandemic levels. The decline will continue. The pandemic has merely acted as a social accelerant (Frost 2020).

 

This view is strengthened if we return to the above graph and look at the group that took the second-biggest hit: American Indians and Alaskan Natives. Their fertility rate has likewise been declining. It was still high in the 1980s, but sometime around 1990 it began to plummet, falling below the fertility rate of any other ethnic group in the U.S. by the early 2000s.

What's going on? Is the decline real? Or is it a statistical fluke? Perhaps sub-fertile Whites are self-identifying as American Indians in growing numbers. This hypothesis was tested by Cannon and Percheski (2017):

 

Concurrent with this decline in estimated TFRs, the self-identified AI/AN population enumerated in the decennial US Census increased in size, largely because of changes in the racial categories and in the wording of racial identity items on the census forms.

 

The increase in the census counts of the American Indian population means that there are several possible explanations for the decline in American Indian fertility rates published by Vital Statistics. First, the decline could be a mechanical artifact of differential changes in racial identification between the two data systems Vital Statistics used to calculate fertility rates. Second, the decline could be driven by compositional changes in who identifies as American Indian. Third, there may be real changes infertility behavior that are unrelated to changes in who identifies as American Indian.

 

To control for these differences in definition and self-identification, Cannon and Percheski (2017) used a single data system (the American Community Survey) for the period 1980 to 2010. They also examined the fertility decline on the basis of three definitions of American Indian/Alaskan native: 1) women who identify as AI/AN only, 2) any woman who identifies as AI/AN, whether identifying one or more races, and 3) women who list a specific tribe or American Indian for the ancestry question. The second definition seems to be the one most vulnerable to "ethnic reassignment."

 

Cannon and Percheski (2017) found that all three definitions showed a fertility decline, particularly the first one. The decline was steepest among younger women. However, there was no indication that lower fertility at younger ages was being offset by higher fertility at older ages. The authors concluded: "This finding of declining TFRs estimated within a single data system is evidence against the explanation that fertility declines are merely artifacts of data collection changes or incongruences."

 

So what is the explanation? The main cause seems to be the declining marriage rate: "fertility rates among married and unmarried women have remained fairly stable, while the share of women ever married has declined across birth cohorts. Thus declines in fertility rates seem to be linked with changes in marriage for this population."

 

In this respect, American Indians are more vulnerable than most other ethnic groups in the U.S. Their women seem to prefer having children when a man is in the home. As the authors note, "other population subgroups in the United States who have experienced substantial declines in marriage have not experienced such drastic declines in fertility levels" (Cannon and Percheski 2017, pp. 8-9). 

 

Anthropologists have long noted that the Indigenous peoples of the Americas still retain many "Arctic" adaptations in their anatomy. Could the same be true for their behavioral predispositions? Some 12,000 years ago, their ancestors lived in northeast Asia and Beringia. In that environment, women had almost no food autonomy and could not raise children on their own. Perhaps their female descendants are still making a half-conscious link between having a baby and having a male provider.

References

 

Cannon, S., and C. Percheski. (2017). Fertility change in the American Indian and Alaska Native population, 1980-2010. Demographic Research 37: 1-12.

http://www.jstor.org/stable/26332188

 

Frost, P. (2020). An Accelerant of Social Change? The Spanish Flu of 1918-19. International Political Anthropology Journal 13(2): 123-133.

https://doi.org/10.5281/zenodo.4295574

 

Hamilton, B.E., M.J.K. Osterman, and J.A. Martin. (2021). Declines in births by month: United States, 2020. NVSS Vital Statistics Rapid Release. Report no. 14, June

https://www.cdc.gov/nchs/data/vsrr/vsrr014-508.pdf

Selection for fair skin in Europeans and North Asians

 

Selection for fair skin in different human populations (Huang et al. 2021)

Selection for fair skin was about four times stronger among ancestral Europeans than it was among ancestral North Asians or the earlier shared ancestors of both groups. So says a recent genome study.

 

Huang et al. (2021) examined genes that influence skin pigmentation to calculate the strength of selection for lighter skin among the ancestors of today’s Europeans and North Asians. They concluded that selection for lighter skin was strongest among the unique ancestors of present-day Europeans, with a selection pressure of 25.9. It was about four times weaker among the unique ancestors of North Asians (5.61) and the earlier shared ancestors of both groups (6.5). East Asians actually became darker after they split from North Asians, with a negative selection pressure of -5.53.

 

Our estimate shows that the modern European lineage had the largest selective pressure (s4=0.0259/generation) on light pigmentation than the other branches, suggesting that recent natural selection favoured light pigmentation in Europeans. Recent studies using ancient DNA could support our observation of recent directional selection in Europeans (Huang et al. 2021, p. 3)

 

This finding supports earlier findings. Modern humans remained dark-skinned in Europe long after they had spread north into northern latitudes some 45,000 years ago. It was not until 20,000 years ago that alleles for white skin made their appearance (Beleza et al. 2013; Canfield et al. 2014; Norton and Hammer 2007). As a Science correspondent concluded: "The implication is that our European ancestors were brown-skinned for tens of thousands of years" (Gibbons 2007).

 

Those ancestors were initially proto-Eurasians, and it was only later that they differentiated to become respectively Europeans and North Asians. Only then, and only in the European lineage, did skin color begin to lighten at a fast rate. This rapid evolution seems to have been confined to a relatively small area that stretched from the Baltic to central Siberia. Elsewhere, in western and southern Europe, people remained dark-skinned until almost the dawn of history, as shown by DNA dated to 11,000 years ago from England, 8,000 years ago from Luxembourg, and 7,000 years ago from Spain (Brace et al. 2019; Lazaridis et al. 2014; Olalde et al. 2014).

 

The fair skin phenotype, together with a variety of hair and eye colors, would later spread throughout all of Europe, while going extinct east of the Urals. In the latter region it would persist into historic times. At sites in south-central Siberia, dating from the third millennium BC to the fourth century AD, genetic analysis has shown that most of the buried individuals had blue or green eyes, light hair (blond, red, light brown), and light skin (Bouakaze et al. 2009). South Siberian peoples were, in fact, described as having "green eyes" and "red hair" in old Chinese records (Keane 1886, p. 703).

 

It seems that Europeans acquired their current appearance very fast, perhaps ten to twenty thousand years ago during the last ice age. Initially confined to northeastern Europe and parts of Siberia, the new phenotype would in time spread to the rest of the continent ... on the eve of recorded history. Only then did all Europeans come to look “European” (Frost 2014; Frost 2020).

 

References

 

Beleza, S., A.M. Santos, B. McEvoy, I. Alves, C. Martinho, E. Cameron, et al. (2013). The timing of pigmentation lightening in Europeans. Molecular Biology and Evolution 30(1): 24-35. https://doi.org/10.1093/molbev/mss207

 

Bouakaze, C., C. Keyser, E. Crubézy, D. Montagnon, and B. Ludes. (2009). Pigment phenotype and biogeographical ancestry from ancient skeletal remains: inferences from multiplexed autosomal SNP analysis. International Journal of Legal Medicine 123(4): 315-325.

https://doi.org/10.1007/s00414-009-0348-5

 

Brace, S., Y. Diekmann, T.J. Booth, Z. Faltyskova, N. Rohland, S. Mallick, et al. (2019). Ancient genomes indicate population replacement in Early Neolithic Britain. Nature Ecology & Evolution 3(5): 765-771. https://doi.org/10.1038/s41559-019-0871-9

 

Canfield, V.A., A. Berg, S. Peckins, S.M. Wentzel, K.C. Ang, S. Oppenheimer, and K.C. Cheng. (2014). Molecular phylogeography of a human autosomal skin color locus under natural selection. G3, 3(11): 2059-2067. https://doi.org/10.1534/g3.113.007484

 

Frost, P. (2014). The puzzle of European hair, eye, and skin color. Advances in Anthropology 4(2): 78-88. http://www.scirp.org/journal/PaperInformation.aspx?PaperID=46104

 

Frost, P. (2020). White Skin Privilege: Modern Myth, Forgotten Past. Evolutionary Studies in Imaginative Culture 4(2): 63-82. https://doi.org/10.26613/esic/4.2.190

https://www.jstor.org/stable/10.26613/esic.4.2.190

 

Gibbons, A. (2007). American Association of Physical Anthropologists Meeting: European skin turned pale only recently, gene suggests. Science 20 April 2007, 316(5823): 364.

https://doi.org/10.1126/science.316.5823.364a

 

Huang, X., S. Wang, L. Jin, and Y. He. (2021). Dissecting dynamics and differences of selective pressures in the evolution of human pigmentation. Biology Open 15 February 2021; 10(2): bio056523. https://doi.org/10.1242/bio.056523

 

Keane, A.H. (1886). Asia with Ethnological Appendix. London: Edward Stanford.

 

Lazaridis, I., N. Patterson, A. Mittnik, G. Renaud, S. Mallick, K. Kirsanow, et al. (2014). Ancient human genomes suggest three ancestral populations for present-day Europeans. Nature 513(7518): 409-413. https://doi.org/10.1038/nature13673

 

Norton, H.L., and M.F. Hammer. (2007). Sequence variation in the pigmentation candidate gene SLC24A5 and evidence for independent evolution of light skin in European and East Asian populations. Program of the 77th Annual Meeting of the American Association of Physical Anthropologists, p. 179.

 

Olalde, I., M.E. Allentoft, F. Sanchez-Quinto, G. Santpere, C.W.K. Chiang, M. DeGiorgio, et al. (2014). Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European. Nature 507 (7491): 225-228. https://doi.org/10.1038/nature12960

 

The large society problem in Northwest Europe and East Asia

 

Allegory of Justice punishing Injustice – Jean-Marc Nattier (Wikicommons). Initially, economic and social activity was organized among closely related individuals, a limitation that kept societies from realizing their full potential as they grew larger. Northwest Europeans and East Asians overcame this limitation through behavioral and mental changes.

I have published an article on "the large society problem in Northwest Europe and East Asia." Comments are welcome.

 

Abstract

 

Kinship was the organizing principle of early societies, defining how people should behave toward each other. Social and economic activity was thus organized mostly among closely related individuals, a limitation that would keep societies from realizing their full potential as they grew larger. The "large society problem" has not been fully solved anywhere, but Northwest Europeans and East Asians have gone the farthest toward a solution. In general, the solution has been to weaken the relative importance of kinship and strengthen forms of sociality that can include everyone, and not just close kin. In particular, one must think and feel in certain ways, i.e., be susceptible to social norms that are absolute, universal, and independent of kinship; feel guilty after breaking social norms; feel empathy for non-kin; and orient oneself toward society. This mindset shows similarities and differences between Northwest Europeans and East Asians. Both groups adapted to a larger social environment by becoming more empathetic toward non-kin and more susceptible to universal social norms. Northwest Europeans became more individualistic while acquiring stronger internal controls of behavior (affective empathy, guilt proneness). East Asians became more collectivistic while acquiring stronger internal controls (cognitive empathy) and stronger external controls (shaming, family-community surveillance, inculcation of normative behavior).

 

 

Reference

 

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

Religion as a force for natural selection

Buddhist temple, Singapore (Wikicommons – Cattan2011). In Buddhism, family is valued over self, but not strangers over family. Christianity goes farther: strangers are valued over self and family.

Originally, and even today in much of the world, social and economic activity is organized mostly by small groups of related individuals. As a result, a society cannot realize its full potential as it grows larger and encompasses people who are less related to each other. This is the “large society problem.” It has been alleviated by making kinship less important and, conversely, by encouraging forms of sociality that include everyone, and not just close kin. Northwest Europeans and East Asians have gone the farthest down that path.

In a large society, a social norm is less situational and more universal; it transcends the situation and its actors. The same applies to norm-breaking. To break a norm is to offend not only a particular person but also a general principle. In time, the principle may be sanctified, thus becoming even more inviolable. Offenders incur the wrath of the entire community, and not just the victim's family (Berman, 1974). Eventually, these reified norms coalesce into "religion."

Religion is key to the cultural environment of large societies and forces humans to adapt to it, just as they had to adapt to the natural environment of small societies. Unlike the natural environment, however, religion is a human creation. We have conceived an idealized vision of what humans should do, and this vision has rewarded those who do right and punished those who do wrong. In short, we have given religion the powers of natural selection. 

This point is made by the authors of a recent study:

Cultural evolution research on religion has highlighted the role religions play in enforcing large-scale cooperation [...]. Religious beliefs that expand what gods know and care about beyond local concerns and the local group, and increase gods' ability to punish rule breakers, may have contributed to sustaining cooperation at larger scales [...]. These beliefs create the perception that one's bad actions will be punished supernaturally, even if undetected by others, and can expand the circle of cooperation to anonymous strangers. Religions that lay out rules for cooperative behavior, and systems to enforce that cooperation, may create more stable and successful groups [...], perhaps increasing the ability of these groups and their religious beliefs to survive and spread. (Willard et al. 2020)

Thus, over time, there has thus been selection for individuals who respond to religion and willingly comply with its norms. Twin studies show that religiosity is 25 to 45% heritable. As is always the case, the non-heritable component includes everything else, like errors in understanding the question and collecting the data. We therefore have a substantial propensity to learn and obey social norms.

This propensity doesn't act alone. A growing child will develop it to a greater extent in a religious environment than in a non-religious one. The kind of religion also makes a difference.

Christianity encourages altruism

Gene-religion interaction has been shown at the gene DRD4. People are made more susceptible to social norms by the 2R allele or the 7R allele and less susceptible by the 4R allele (Sasaki et al., 2013). Furthermore, this susceptibility interacts with religion in the development of altruism. Using American and East Asian participants, Sasaki et al. (2013) found that 2R and 7R carriers were more altruistic than non-carriers if previously primed by the task of making a sentence from religious-sounding words. Priming had no effect on non-carriers.

These findings were partially replicated by Jiang et al. (2015). Among Singaporeans of Chinese descent, 2R carriers were more altruistic than non-carriers among male Christians, while being the same as non-carriers among women, Taoists, and Buddhists. The authors argue that men have more room for improvement because women start off caring more about others. The authors further suggest that Christianity better supports altruism by offering fellowship, comprehensible texts, and regular activities. Thus, if people are already more susceptible to social norms, they will become more altruistic if their environment is Christian. If, however, their environment is non-Christian, they will be no more altruistic than anyone else.

Because Christianity is better at developing this innate potential, and because this potential differs from one individual to another, altruism will vary much more among Christians than among non-Christians. A Christian society will have far more "super altruists" as a proportion of its population. This can be advantageous. Such people were once priests, pastors, nuns, philanthropists and the like. Before the rise of the welfare state, they provided valuable "collective goods," like education, moral guidance, and care for the sick and elderly. But what happens when a Christian society becomes post-Christian? For a while, there will still be lots of super altruists, but they will no longer be priests or pastors. They will become social justice warriors.

Taoism and Buddhism encourages veneration of ancestors and support for one’s in-group

Willard et al. (2020) studied how different religions affect prosocial behavior among Singaporeans of Chinese descent. Certain religious beliefs seemed to be key:

A moral afterlife

Buddhism, Taoism, and Christianity all share a belief that good deeds will be rewarded and evil deeds punished in an afterlife. When cued to think about the afterlife, participants from all three religions expressed a greater willingness to assist strangers.

Veneration of ancestors

Veneration of ancestors is an older stage of religious belief. It began in small societies but can be used to make large societies more workable, as long as everyone shares some common ancestry—or at least a belief in common ancestry.

Participants from all three religions believed that ancestors should be venerated, but this belief was supported much more by Buddhism and Taoism than by Christianity. When participants were cued to think about ancestor veneration, the Buddhists and Taoists expressed a greater willingness to assist their family and their in-group than did participants in the control condition. This effect was absent in the Christians: in fact, they became more willing to assist strangers:

When cued to think about moralized afterlife beliefs, Buddhists showed larger increases across almost all questions than Christians in what they believed was the normative amount to give. This effect is driven by Buddhists claiming weaker norms of giving than Christians in the neutral conditions on many of the questions. Though the moralized afterlife prime produced a greater change here, it brings both groups up to relatively similar normative amounts [...]. The ancestor condition generated weaker prosocial effects for Buddhists and Taoists on allocations to strangers than for Christians. In fact, the Christians showed a stronger effect here than anticipated, and the effects of the ancestor condition were stronger than those of the moralized afterlife condition on all questions. (Willard et al. 2020)

Conclusion

Religion encourages selflessness, but to varying degrees and to varying levels. In Buddhism and Taoism, family is valued over self, but not strangers over family. Christianity goes farther; strangers are valued over self and family. The Christian religion is thus more useful in large societies whose members don’t even pretend to share common ancestry.

References

Berman, H. J. (1974). The Interaction of Law and Religion. Nashville, Abingdon Press.

http://www.socialtheology.com/docs/berman-law-and-religion-000074.pdf

Bouchard, T.J. Jr., (2004). Genetic influence on human psychological traits: A survey. Current Directions in Psychological Science 13: 148-151.

http://www.stafforini.com/docs/bouchard_-_genetic_influence_on_human_psychological_traits.pdf

Jiang, Y., R. Bachner-Melman, S.H. Chew, and R.P. Ebstein. (2015). Dopamine D4 receptor gene and religious affiliation correlate with dictator game altruism in males and not females: evidence for gender-sensitive gene × culture interaction. Frontiers in Neuroscience 24 September.

https://www.frontiersin.org/articles/10.3389/fnins.2015.00338/full

Lewis, G.J. and T.C. Bates. (2013). Common genetic influences underpin religiosity, community integration, and existential uncertainty. Journal of Research in Personality 47: 398-405.

http://timbates.wdfiles.com/local--files/cv/Lewis%20%26%20Bates%202013%20%28JRP%29%20Common%20genetic%20influencesunderpin%20religiosity%2Ccommunity%20integration%2Cand%20existential%20uncertainty.pdf

Sasaki, J.Y., H.S. Kim, T. Mojaverian, L.D.S Kelley, I.Y. Park, and S. Janušonis. (2013). Religion priming differentially increases prosocial behavior among variants of the dopamine D4 receptor (DRD4) gene. Social Cognitive and Affective Neuroscience 8(2): 209-215.

https://labs.psych.ucsb.edu/kim/heejung/sasakietalscan.pdf

Willard, A.K., A. Baimel, H. Turpin, J. Jong, and H. Whitehouse. (2020). Rewarding the good and punishing the bad: The role of karma and afterlife beliefs in shaping moral norms. Evolution and Human Behavior in press.

https://www.sciencedirect.com/science/article/pii/S1090513820300805?dgcid=raven_sd_aip_email 

Did women jumpstart recent cognitive evolution?

Scatter plots of frequencies of CASC5 variants by sex (Shi et al. 2017). During the last ice age, natural selection favored an increase in the gray matter of ancestral East Asians ... primarily in women.

Back in 2005 there was much interest in genes that regulate brain size, particularly in the ways they varied geographically within our species. It was found that two of these genes, Microcephalin and ASPM, continued to evolve as modern humans spread out of Africa. The latest variant of Microcephalin arose some 37,000 years ago in Eurasia and is still largely confined to the indigenous peoples of Eurasia and the Americas (Mekel-Bobrov et al. 2005). The latest variant of ASPM appeared even later, some 5,800 years in the Middle East (Evans et al. 2005).

Interest fell off when no association could be shown between the new variants and IQ or brain size (Mekel-Bobrov et al. 2007; Rushton et al. 2007; see also Frost 2020). Since then, we have learned that the new ASPM variant is associated with a larger cerebral cortex, and not a larger brain as a whole. Overall brain volume seems to be constrained in modern humans, perhaps by the breadth of a woman's pelvis during childbirth or simply by the high metabolic costs of brain tissue (Ali and Meier 2008; Frost 2020). As for the lack of an association with IQ, we now know that IQ correlates poorly or not at all with some cognitive abilities, like executive function and face recognition.

But what do the new variants actually do? Perhaps a specialized mental task.  It has been suggested that the new ASPM variant assists the brain in processing non-tonal language or alphabetical script (Dediu and Ladd 2007; Frost 2007).

CASC5, another gene for brain growth

Interest has since grown in another gene that regulates brain growth, CASC5. Like Microcephalin and ASPM, it has undergone recent evolution in the modern human lineage:

[...] the CASC5 gene contains mutations in modern humans, but not in Denisovans (Meyer et al. 2012) and this gene also shows distinct sequence divergence between modern humans and Neanderthals (Prufer et al. 2014). These data suggest that CASC5 is an important gene for human neurogenesis, and may harbor modern human specific mutations contributing to the recent evolutionary change of the human brain. (Shi et al. 2017)

Shi et al. (2017) found evidence of recent evolutionary change. Specifically, two nucleotides of CASC5 have been replaced with a new variant in all modern humans. Six other nucleotides have become polymorphic, with some people having the new variants and others not. These polymorphisms show regional differences:

- In four of the polymorphisms, the new variant has a much higher frequency in East Asians than in Europeans or Africans.

- In one polymorphism, it has a much higher frequency in Europeans than in the other two regional groups.

- The remaining polymorphism shows no differences in frequency between the three regional groups.

By and large, the new variants have been under strong positive selection, particularly among East Asians. When the authors examined the six polymorphisms, they found signals of selection for five of them in East Asians and for one in Europeans.

The new variants and brain characteristics

The authors then looked for correlations between the new variants and certain characteristics of the brain, specifically total brain volume, gray matter volume, and white matter volume. To this end, 267 healthy participants were recruited for brain imaging (Han Chinese, 178 females and 89 males, mean age 35.4 ± 12.5 years). All of them were free from mental disorders, drug abuse, alcohol dependence, and brain injury.

Gray matter was significantly larger in participants with the new variant than in those with the ancestral variant at five of the nucleotide sites, including the four polymorphic ones—the same ones that showed differences in variant frequency between East Asians and Europeans. When the authors examined the one polymorphism whose variants were equally common in East Asians, Europeans, and Africans, they found no brain differences between participants with the new variant and those with the ancestral one.

When the authors broke their data down by sex, they found that the new variants were significantly associated with a higher volume of gray matter only in women, not in men, although men seemed to trend in the same direction. The authors suggest that this effect would be significant in men if the number of male participants were larger. Probably. But it seems to me there would still be a sex difference, the number of participants being already large enough.

Ice age origin of the new variants

The authors say the new variants became prevalent "after modern humans migrated out of Africa less than 100,000 years ago." We can narrow down the time range further. The new variants are also present at high frequencies among the indigenous peoples of North and South America; therefore, they must have become prevalent before ancestral Amerindians crossed into North America some 12,000 years ago, apparently in a population that was ancestral both to Amerindians and to East Asians. That would be long before the time of recorded history and even before the Holocene, at a time when northern Eurasia was experiencing glacial conditions.

Did those conditions select for cognitive ability? Cold, seasonal environments did impose new cognitive demands on early modern humans, first by increasing their need to plan ahead over a yearly cycle and second by providing them with new tasks: garment making, needlework, weaving, leatherworking, and kiln operation. Women performed those tasks because the environment offered them few opportunities for food gathering—the usual female activity before the advent of farming. They thus moved into artisanal tasks that not only required greater cognitive ability but also offered much potential for further development. This was the "original industrial revolution" and it was led by women (Frost 2019a).

We can better understand this sexual division of labor by studying northern hunter-gatherers of recent times. According to a cross-cultural study, if women are less involved in food gathering, they specialize in activities unrelated to food procurement, i.e., house building, leatherworking, and burden carrying (Waguespack 2005). A study of two Inuit groups found the highest degree of technological complexity in garment making and shelter building, both of which are wholly or largely women's work (Oswalt 1976). Cold environments thus change the sexual division of labor among hunter-gatherers in a crucial way: while men continue to be food providers, women develop new technologies.

These findings may explain the recent evolution of CASC5: women were the focus of selection for cognitive ability during Ice Age times. But why was the selection stronger among ancestral East Asians than among ancestral Europeans? It looks like the climate at that time was more severe in northern Asia than in northern Europe. Europe benefited from the moderating influence of the Atlantic, which made for a milder and moister climate. Conditions were much colder and drier in northern Asia.

The evolution of human intelligence cannot be reduced to a single unified theory. Cold environments emancipated women from the mental straitjacket of food gathering, thus putting humans on the path to social complexity. That path, however, would take them to latitudes farther south in temperate and even tropical environments where they would be exposed to new cognitive demands. With the end of hunting, men moved not only into farming but also into the artisanal activities that women had developed. The same period saw a decline in brain volume that was greater in women than in men—an indication that cognitive demands were particularly high before the Holocene, and even more so for women (Frost 2019b).

The Holocene thus saw northern populations expand southward and eventually cover almost all of Eurasia, North Africa, Oceania, and the Americas. Those populations had a cognitive advantage that made them better able to exploit the social complexity emerging farther south. This point was made by Darwin's colleague Alfred Russel Wallace:

So when a glacial epoch comes on, some animals must acquire warmer fur, or a covering of fat, or else die of cold. Those best clothed by nature are, therefore, preserved by natural selection. Man, under the same circumstances, will make himself warmer clothing, and build better houses; and the necessity of doing this will react upon his mental organisation and social condition [...] a hardier, a more provident, and a more social race would be developed, than in those regions where the earth produces a perennial supply of vegetable food, and where neither foresight nor ingenuity are required to prepare for the rigours of winter. And is it not the fact that in all ages, and in every quarter of the globe, the inhabitants of temperate have been superior to those of tropical countries? All the great invasions and displacements of races have been from North to South, rather than the reverse.

References

Ali, F. and R. Meier. (2008). Positive selection in ASPM is correlated with cerebral cortex evolution across primates but not with whole brain size. Molecular Biology and Evolution 25(11): 2247-2250.

https://www.researchgate.net/profile/Rudolf_Meier/publication/23185977_Positive_Selection_in_ASPM_Is_Correlated_with_Cerebral_Cortex_Evolution_across_Primates_but_Not_with_Whole-Brain_Size/links/00b7d53ad237958edd000000.pdf

Dediu, D., and R. Ladd. (2007). Linguistic tone is related to the population frequency of the adaptive haplogroups of two brain size genes, ASPM and Microcephalin. Proceedings of the National Academy of Sciences 104(26): 10944-10949

https://langev.com/pdf/dediu07linguisticTonePNAS.pdf

Evans, P. D., Gilbert, S. L., Mekel-Bobrov, N., Vallender, E. J., Anderson, J. R., Vaez-Azizi, L. M., et al. (2005). Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans. Science 309: 1717-1720.

http://web.stanford.edu/class/cs273a/papers.spr07/lecture15/Microencephalin.pdf

Frost, P. (2007). The spread of alphabetical writing may have favored the latest variant of the ASPM gene. Medical Hypotheses 70: 17-20.

http://www.sciencedirect.com/science/article/pii/S0306987707003234

Frost, P. (2019a). The Original Industrial Revolution. Did Cold Winters Select for Cognitive Ability? Psych 1(1): 166-181

https://doi.org/10.3390/psych1010012

Frost, P. (2019b). Why did brain size decrease after the ice age? Evo and Proud, July 6

https://evoandproud.blogspot.com/2019/07/why-did-brain-size-decrease-after-ice.html

Frost, P. (2020). A second look at ASPM. Evo and Proud, April 14

https://evoandproud.blogspot.com/2020/04/a-second-look-at-aspm.html

Mekel-Bobrov, N., S.L. Gilbert, P.D. Evans, E.J. Vallender, J.R. Anderson, R.R. Hudson, S.A. Tishkoff and B.T. Lahn. (2005). Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens. Science 309: 1720-1722

https://www.researchgate.net/publication/7611130_Ongoing_Adaptive_Evolution_of_ASPM_a_Brain_Size_Determinant_in_Homo_Sapiens

Mekel-Bobrov, N., D. Posthuma, S.L. Gilbert, P. Lind, M.F. Gosso, et al. (2007). The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence. Human Molecular Genetics 16(6): 600-608.

https://academic.oup.com/hmg/article/16/6/600/610971

Oswalt, W.H. (1976). An Anthropological Analysis of Food-Getting Technology, 1st ed.; John Wiley and Sons: New York, NY, USA.

Rushton, J.P., P.A. Vernon, and T.A. Bons. (2007). No evidence that polymorphisms of brain regulator genes Microcephalin and ASPM are associated with general mental ability, head circumference or altruism. Biology Letters-UK 3(2): 157-60.

https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2006.0586

Shi, L., Hu, E., Wang, Z. et al. (2017). Regional selection of the brain size regulating gene CASC5 provides new insight into human brain evolution. Human Genetics 136: 193-204. https://doi.org/10.1007/s00439-016-1748-5

http://ir.ioz.ac.cn/bitstream/000000/12812/1/Regional%20selection%20of%20the%20brain%20size%20regulati1.pdf

Waguespack, N.M. (2005). The organization of male and female labor in foraging societies: Implications for early Paleoindian archaeology. American Anthropologist 107: 666-676.

https://pdfs.semanticscholar.org/8e50/02b23a25d1a97054f8bf9b8b852d2151a093.pdf

Wallace, A.R. (1864). The Origin of Human Races and the Antiquity of Man deduced from the Theory of "Natural Selection." Journal of the Anthropological Society of London, 2, clviii-clxxxvii, Alfred Russel Wallace Classic Writings. Paper 6. http://digitalcommons.wku.edu/dlps_fac_arw/6