Friday, July 29, 2022

Recent evolution in Estonia


Estonian women at a song festival (Wikicommons – Anastasia Lakhtikova)


Estonian women had more reproductive success during the late 20th century if they possessed a more masculine body build, narrower hips, and shorter legs. Such women married earlier and were less likely to stay on the mate market as long as possible.


Human evolution didn’t end in the Pleistocene. In fact, there has been more genetic change within our species over the past 10,000 years than over the previous 100,000, and perhaps more than over the previous million. The growing importance of culture did not slow down the pace of genetic change. In fact, culture became the main driving force of genetic evolution by replacing adaptation to a limited number of natural environments with adaptation to an ever-widening range of cultural environments (Cochran and Harpending 2009; Hawks et al. 2007; Rinaldi 2017).


Two years ago, I reviewed a study on recent evolution in the Estonian population (Frost 2020; Hõrak and Valge 2015). Among Estonians born between 1937 and 1962, women with only primary education had 0.5 to 0.75 more children than did women with tertiary education. This difference in reproductive success correlated with difference in cranial volume: children with larger crania were more likely to go on to secondary or tertiary education, independently of sex, socioeconomic position, and rural vs urban origin (Valge et al. 2019). Thus, for Estonian women in the late 20th century, higher education decreased fertility, probably by postponing the age of marriage.


That finding was found only for women. Perhaps Estonian men with higher education enjoyed greater reproductive success, in which case selection for less intelligent women may have been cancelled out by selection for more intelligent men.


The same research team has now published a new study of the same dataset, this time on both sexes. They confirm the original finding that female fertility correlated negatively with education and cranial volume. As for male fertility, although it correlated positively with education, the most fertile males had only average cranial volume. The authors had no explanation for that finding:


Stabilizing selection on the cranial volume of boys was an unexpected result, given that cranial volume in our study population predicts educational attainment independently of sex, socioeconomic background, and height. Since educational attainment was a strong predictor of fatherhood in our study, we would have expected positive directional selection on cranial volume. However, we found only evidence for stabilizing selection (Valge et al. 2022)


Perhaps women prefer men who are well-educated but not excessively intelligent. As one goes farther and farther away from the mean IQ of a population, higher intelligence becomes more and more often due to genetic “accidents”—unusual genetic variants or combinations of variants that may adversely affect other aspects of mind and behavior. A very intelligent person may seem autistic or have poor social skills.


The new study also shows that women had greater reproductive success if they possessed a more masculine body build, narrower hips, and shorter legs. That finding may seem counterintuitive. Don’t men prefer feminine-looking women? They do. However, as the authors show by citing earlier findings, shorter women are also less selective and likelier to marry earlier:


Similar reasoning might also explain why selection favored girls with masculine body build, narrow hips, and absolutely and relatively shorter legs in our study. If choosiness in women increases with desirability, this could lead to women with more feminine phenotypes engaging in a more time-consuming mate selection process, delaying their age of first birth, and thereby negatively affecting reproduction. (Valge et al. 2022)


Finally, the new Estonian study shows that heavier and stronger boys had more reproductive success.


The results relating to height and strength are consistent with studies of sexual selection showing that men who are taller, stronger, and more physically fit are generally perceived as more physically attractive by women, and therefore, have better opportunities for partnering and becoming a father. For instance, in a sample of Polish men born in the 1930s, childless men appeared significantly shorter than those with at least one child. In West Point graduates, the number of children increased linearly with height because taller men had higher probabilities of marrying more than once. Barclay and Kolk showed in a sample of 405,427 Swedish conscripts born between 1965 and 1972 that men in the lowest deciles of height, and in particular, physical fitness in early adulthood, had the lowest probabilities of transition to parenthood. (Valge et al. 2022)


Final thoughts


This is a study of Estonians who were born more than a half-century ago, long before the breakup of the Soviet Union. Things may be different now. Estonians have rapidly converged on Western social, behavioral, and ideological norms over the past three decades. Although their country is nominally independent, they are now strongly influenced by the inflow of Western culture via the media, and this new media environment is having a decisive impact on how they think and act (Karlin 2018).


Estonia is generally following the lead of the West. With respect to education and fertility, the negative correlation has become stronger throughout the West: “In all countries [Australia, United States, Norway, Sweden], however, education is negatively associated with childbearing across partnerships, and the differentials increased from the 1970s to the 2000s” (Thomson et al. 2014).


This differential is increasing not only between families but also within “families.” Second and third children are born increasingly to women who have divorced and are in relationships with low-quality fathers who often seem to be little more than sperm donors. In Norway, multi-partner fatherhood has become most common among men with the lowest level of education (10 years of schooling, "i.e., compulsory education"):


At age 45, about 15 percent of all men in the 1960-62 cohort with a compulsory education had had children with more than one woman, compared to about 5 percent among men with a tertiary degree. If looking at fathers only (Figure 6), the pattern becomes even more pronounced. At the lowest educational level, 19.3 percent of those who had become fathers, had children with more than one woman, compared to 6.1 percent of those at the highest educational level. (Lappegård et al. 2011)


This trend may partly explain the slowing down and reversal of the Flynn effect, i.e., the steady rise in mean IQ over the 20th century. There is some debate over whether the Flynn effect was a real increase in intelligence or simply an increase in familiarity with doing tests. In any case, its reversal seems real enough.


With respect to Norway, Bratsberg and Rogeberg (2018) have shown that the decline in mean IQ can be explained by “within-family variation.” In other words, mean IQ is declining among people who supposedly share the same genetic background, i.e., siblings. In Norway, however, siblings are increasingly half-siblings. Among Norwegian women with only two children, 13.4% have had them by more than one man. The figure rises to 24.9% among those with three children, 36.2% among those with four children, and 41.2% among those with five children (Thomson et al. 2014). 


The family unit is decomposing throughout the West. It is becoming little more than an administrative entity that can be repeatedly dissolved and reconstituted (Frost 2018a; Frost 2018b).





Bratsberg, B., and O. Rogeberg. (2018). Flynn effect and its reversal are both environmentally caused. Proceedings of the National Academy of Sciences 115 (26) 6674-6678


Cochran, G. and H. Harpending. (2009). The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. Basic Books: New York.


Frost, P. (2018a). Why is IQ declining in Norway? Evo and Proud, June 19.


Frost, P. (2018b). Yes, the decline is genetic. Evo and Proud, June 26.


Frost, P. (2020). Declining intelligence in the 20th century: the case of Estonia. Evo and Proud, August 3.


Hawks, J., E.T. Wang, G.M. Cochran, H.C. Harpending, and R.K. Moyzis. (2007). Recent acceleration of human adaptive evolution. Proceedings of the National Academy of Sciences (USA) 104: 20753-20758.


Hõrak, P., and M. Valge. (2015). Why did children grow so well at hard times? The ultimate importance of pathogen control during puberty. Evolution, Medicine, and Public Health (1): 167–178,


Karlin, A. (2018). Gay marriage in Estonia. The Unz Review, October 30.


Lappegård, T., Rønsen, M., and Skrede, K. (2011). Fatherhood and fertility. Fathering 9: 103-120.


Rinaldi, A. (2017). We're on a road to nowhere. Culture and adaptation to the environment are driving human evolution, but the destination of this journey is unpredictable. EMBO reports 18: 2094-2100.


Thomson, E., T. Lappegård, M. Carlson, A. Evans, and E. Gray (2014). Childbearing across partnerships in Australia, the United States, Norway, and Sweden. Demography 51(2): 485-508. 


Valge, M., R. Meitern, and P. Hõrak.  (2022). Sexually antagonistic selection on educational attainment and body size in Estonian children. Annals of the New York Academy of Sciences Early view

Sunday, July 17, 2022

Cognitive evolution on the Italian Peninsula


A recent polygenic study has shown that mean cognitive ability is higher in the North of Italy than in the South. Cognitive evolution seems to have gone the farthest in the Northeast, perhaps because the Northwest earlier went through the Industrial Revolution, which severed reproductive success from economic success.




As a country, Italy came into existence only a century and a half ago. Regional differences are still strong, particularly between the North and the South. The “Southern question” is usually said to date from the unification of Italy in the 19th century:


In the decades following the unification of Italy, the northern regions of the country, Lombardy, Piedmont and Liguria in particular, began a process of industrialization and economic development while the southern regions remained behind. At the time of the unification of the country, there was a shortage of entrepreneurs in the south, with landowners who were often absent from their farms as they lived permanently in the city, leaving the management of their funds to managers, who were not encouraged by the owners to make the agricultural estates to the maximum. Landowners invested not in agricultural equipment, but in such things as low-risk state bonds. (Wikipedia 2022a)


De Rosa (1979) argues that the South had already fallen behind the North by the 18th century. At that time, its middle class was small, and economic relations were still structured by paternalism and familialism. One could go back even farther, to the Renaissance or even the late Middle Ages, to identify the moment when northern Italy, and Western Europe in general, embarked on sustained economic growth and thus pulled ahead of the rest of the world.


That sustained economic growth brought sustained demographic growth, particularly of the middle class. Gregory Clark found that the English middle class expanded steadily from the twelfth century onward, its descendants not only growing in number but also replacing the lower classes through downward mobility. By the 1800s, its lineages accounted for most of the English population. That demographic change coincided with mental and behavioral changes: higher cognitive ability, lower time preference, and a lower threshold for violent behavior. In a word, the English became more middle-class in character. “Thrift, prudence, negotiation, and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent, and leisure loving” (Clark 2007, p. 166).


Elsewhere in Western Europe, the middle class similarly expanded during late medieval and early modern times. The result would be a growing contrast between regions that had participated in this economic and demographic change and those that had not, such as southern Italy. The contrast can be seen not only on purely economic measures but also on mental ones, like the INVALSI standardized test—an annual test of skills in Italian schools. It is divided into two sections: Italian language skills and Math skills. On both tests, northern Italian students do better than southern Italian students, the difference being a little over half a standard deviation:


Yes, the North-South gap in academic achievement could have a purely environmental cause—and this is a recurring problem when we try to tease apart genetic and cultural evolution. If economic development is held back by a culture of poverty, that same culture may discourage students from trying to do better at school. Those students may also have less access to proper nutrition, medical care, libraries, and so on.


Polygenic scores for cognitive ability


That is why there is so much interest in measures of innate cognitive ability. The most promising one is the polygenic score (PGS)—the summation of alleles (genetic variants) that have been associated with cognitive ability, as measured by educational attainment.  At present, we have identified enough of these alleles to explain 11-13% of the overall variation in cognitive ability (Lee et al. 2018).


Yes, those alleles are just a sample of the total number, but why would they be an unrepresentative sample? More to the point: why would PGS data show certain geographic patterns and not a lot of random noise? The mean PGS does indeed differ geographically among human populations. It is highest in Eurasia, with East Asians, Ashkenazi Jews, and Finns having the highest scores. That geographic pattern is in line with IQ data (Piffer 2019).


Polygenic scores on the Italian Peninsula


In a recent study, Piffer and Lynn (2022) have found regional differences in Italy for alleles associated with educational attainment. They used two datasets: one encompassing 129 Italian individuals and the other 947. All of these individuals had all four grandparents born in the same part of Italy (this requirement was imposed to eliminate the effects of recent interregional migration). When the authors grouped the data into three large regions—North, Central, and South—they found “a clear north-south gradient, with central Italians occupying an intermediate position.” There was more overlap between central and southern Italians than between central and northern Italians.


The datasets were too small to show genetic differences within each of the three large regions. If we go back to the INVALSI data, we see that academic achievement is much stronger in the North-Northeast (Lombardia, Trentino, Veneto, Friuli) than in the Northwest (Valle d’Aosta, Liguria).


At first thought, that geographic pattern may seem counter-intuitive. In northern Italy, industrialization began in the northwest and came later to the northeast: “the diffusion of industrialisation that characterised the northwestern area of the country largely excluded Venetia and, especially, the South” (Wikipedia 2022b). If economic development had driven cognitive evolution on the Italian Peninsula, why would this evolution have gone farther in the northeast? Why would it be negatively associated with industrialization?


Because the Industrial Revolution put a stop to cognitive evolution. It severed the link between economic success and reproductive success. Previously, businesses were family-run, and the family provided the workforce. Successful business owners were incentivized to have larger families, and their children would have the means to marry at a younger age. Then, in the late 19th century, that stage of economic development began to give way to industrial capitalism. Financial success no longer translated into early marriage and large families who could help with the work. If more workers were needed, they would simply be hired. Business owners now tended to have smaller families because of the high maintenance costs of middle-class children (Canlorbe and Frost 2020; Frost 2018).


Cognitive evolution thus ended earlier in the Northwest of Italy than in the Northeast. By the same token, interregional migration has had more time to erode the cognitive advantage that evolved in the Northwest. Yes, the datasets were limited to people who had all four grandparents born in the region, but, for most people, that limitation would not eliminate the effects of interregional migration before the mid-20th century.





Canlorbe, G., and P. Frost (2020). Why are human groups so different? American Renaissance, March 20.  


Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World, 1st ed. Princeton University Press: Princeton, NJ, USA.


De Rosa, L. (1979). Property Rights, Institutional Change, and Economic Growth in Southern Italy in the XVIIIth and XIXth Centuries. Journal of European Economic History 8(3): 531-551.


Frost, P. (2018). Rise of the West. Part II. Evo and Proud, December 27  


Lee, J. J., Wedow, R., Okbay, A., Kong, E., Maghzian, O., Zacher, et al. (2018). Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals. Nature Genetics 50(8): 1112-1121.


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.    


Piffer, D., & Lynn, R. (2022). In Italy, North-South Differences in Student Performance Are Mirrored by Differences in Polygenic Scores for Educational Attainment. Mankind Quarterly 62(4), Article 2.  


Wikipedia (2022a). Economy of Italy – Southern Question  


Wikipedia (2022b). Economic history of Italy.  


Thursday, July 7, 2022

Adapting to bubonic plague


Rash associated with familial Mediterranean fever (Wikicommons – Dr. H.J. Lachman)


In the eastern Mediterranean, people were likelier to survive bubonic plague if they had stronger inflammatory responses to infection in their lungs, gut, and other tissues. Today, that natural selection is attested by a high incidence of familial Mediterranean fever.


Familial Mediterranean fever is due to mutations that increase the body’s production of pyrin, a protein that assists inflammatory responses to infection of the lungs, gut, and other tissues. It’s common among eastern Mediterranean peoples, like Jews, Syrians, Armenians, Turks, Greeks, and Italians. The most common symptoms are inflammation of the abdominal lining, the joints, and the chest. Some kind of natural selection seems likely because different mutations have evolved independently to produce the same disease within the same geographic region.


Several years ago, Greg Cochran suggested this fever might be an adaptation to trypanosome parasites (Leishmaniasis). Recent research now suggests an adaptation to bacteria of the genus Yersinia. Y. pestis causes bubonic plague, whereas Y. pseudotuberculosis and Y. enterocolitica cause gastroenteritis. These pathogens are highly infectious because they decrease the body’s production of pyrin and thus reduce its ability to fight infection. To compensate for this underproduction of pyrin, there seems to have been selection for mutations that cause overproduction of pyrin, hence the high incidence of familial Mediterranean fever in populations that have coexisted with Yersinia bacteria (Loeven et al. 2020).


Yepiskoposyan and Harutyunyan (2007) argue that selection for familial Mediterranean fever must have begun more than 2,500 years ago, since one of the alleles responsible for it is found in different communities of the Jewish diaspora, notably Iraqi and North African Jews. That argument doesn’t convince me, since diaspora communities were not reproductively isolated. The mutation could have arisen in one community and then been spread to others by Jewish individuals moving from one place to another.


I’m inclined to believe that selection for this fever began with the earliest recorded outbreak of bubonic plague: the Plague of Justinian (541-549 AD), which killed an estimated 25 million people throughout the Mediterranean Basin and the Middle East. An earlier date is nonetheless possible, since Y. pestis has been attested in archaeological finds as far back as 5,000 years ago (Wikipedia 2022).





Chung, L.K., Y.H. Park, Y. Zheng, I.E. Brodsky, P. Hearing, D.L. Kastner, J.J. Chae, and J.B. Bliska. (2016). The Yersinia Virulence Factor YopM Hijacks Host Kinases to Inhibit Type III Effector-Triggered Activation of the Pyrin Inflammasome. Cell Host Microbe 20(3):296-306.


Cochran, G. (2015). Familial Mediterranean fever. West Hunter, January 9.


Loeven, N.A., N.P. Medici, and J.B. Bliska. (2020). The pyrin inflammasome in host-microbe interactions. Curr Opin Microbiol 54:77-86.


Wikipedia (2022). Bubonic plague.


Yepiskoposyan, L., and A. Harutyunyan. (2007) Population genetics of familial Mediterranean fever: a review. Eur J Hum Genet 15: 911–916.