Why that stereotype and not the other?

Nubian Pyramids (Wikicommons - Petr Adam Dohnalek). In classical antiquity, contacts with black Africans were largely with Nubians, a people who already enjoyed a high level of material culture. 



A decade ago, Jason Malloy noted a curious fact: the ancient world did not see sub-Saharan Africans as less intelligent, despite the existence of other stereotypes, like macrophallia (Frost 2009, see comments; Thompson 1989). A stereotype of low intelligence is recorded in only two Greco-Roman texts, to the best of my knowledge. One is a reference by Ibn Khaldun (1332-1406 AD) to the Greek physician Galen (129-210 AD). The statement attributed to Galen does not appear in any of his works, at least not in those that have survived, and may be a false attribution.

We have seen that Negroes are in general characterized by levity, excitability, and great emotionalism. They are found to dance wherever they hear a melody. They are everywhere described as stupid. ... Al-Masfiüdi undertook to investigate the reason [for this]. However, he did no better than to report on the authority of ... al-Kindi and Jalinus [Galen] that the reason is a weakness of their brains which results in a weakness of their intellects. This is an inconclusive and unproven statement. ... The real reason is that ... joy and gladness are due to the expansion and diffusion of the animal spirit. Sadness is due to the opposite. (Hunwick 2005)

The other is the Christian parable of the Ethiopian woodcutter. The desert monk Arsenius (350-445 AD) recounted how an Ethiopian went out to gather wood. When the burden became too heavy, he put it down and continued to gather, but now his load was even heavier. So he put it down and gathered even more (Wallis Budge 1907). This parable is from late antiquity and may reflect the growing influx of black slaves into the Middle East during that period.

It seems, then, that low intelligence was not attributed to sub-Saharan Africans during classical antiquity, at least not often enough to become a stereotype. This stereotype would emerge later, during late antiquity and even more so during the Islamic period (Lewis 1990, pp. 46-47, 92-97).

I suspect there were two reasons:

- mean intelligence was probably lower in the Mediterranean world during classical antiquity, perhaps in the low 90s. This would be consistent with the apparently smaller size of its "smart fraction," in contrast not only to Western societies in later times but also to ancient Greece in earlier times (see July 13 post). In Roman society, intellectuals seem to have largely been isolated individuals. They did not come together to hold regular conferences or publish journals. While there were elementary schools, the ludus litterarius, there were no institutions of higher learning, only private tutors. The difference in mean intelligence with sub-Saharan Africa would have thus seemed smaller.

- contacts with dark-skinned Africans were initially most frequent with Nubians, who under Egyptian influence already enjoyed a high level of material culture and were thus already being selected for cognitive ability. Contacts with peoples farther south developed later, with development of the African slave trade. This trade seems to have slowly but steadily increased in volume during late antiquity and, subsequently, the Islamic period (Frost 2008).


Civilization and intelligence

So, beyond a certain point, does civilization actually select against intelligence? The short answer: yes, in some cases. 

Now for the long answer. First, increased intelligence comes at a cost:

The brain requires about 22 times as much energy to run as the equivalent in muscle tissue. The energy required to run every bodily process comes from the food we eat. Human brains are three times larger than our closest living relative, the chimpanzee, and use up to three times the energy, but the two species have the same metabolic rate. (Welsh 2011)

Because of that high energy cost, any excess intelligence is under strong negative selection and will decline noticeably—even over a few generations. Positive selection becomes confined to a minority of the population as a civilization develops and moves toward specialization of labor, i.e., the most difficult intellectual work is done by a minority while the majority performs menial tasks. 

Nonetheless, we have examples of advanced civilizations, notably in East Asia from ancient times and, later on, in Western Europe, where mean intelligence was and still is quite high. Those civilizations likewise had specialization of labor. So what made them different?

It seems to have been a process of internal demographic replacement that Gregory Clark described with respect to England and Ron Unz with respect to China. The mean intelligence of an entire population will steadily rise if two conditions are met:

1. Fertility is higher in higher social classes.

2. Class boundaries are sufficiently porous that the resulting demographic surplus of these classes can move downward and replace the lower classes.

Historically and cross-culturally, these two conditions were far from universal. In many societies, surplus members of the upper class preferred to remain unmarried and wait for a suitable high-status niche to open up. It was shameful to "lose caste" and enter a niche lower on the social ladder. Nor was fertility universally higher in higher social classes. In some cases, the rich and powerful had fewer children because they could count on other means of support for their old age. In other cases, they tended to congregate in towns and cities, where infant mortality was higher. Finally, greater sexual access to women often failed to translate into reproductive success because of infertility due to STDs or because of a culture of debauchery and indifference to married life.


Conclusion

With ancient DNA and polygenic cognitive scores, we can now understand history in a new light. Mean intelligence has risen and fallen during the time of recorded history, and not simply because of migrant influxes. The people may have been the same, and yet they really weren't:

Since it looks like there has been significant evolutionary change over historical time, we're going to have to rewrite every history book every written," said Gregory Cochran, a population geneticist at the University of Utah. "The distribution of genes influencing relevant psychological traits must have been different in Rome than it is today," he added. "The past is not just another country but an entirely different kind of people” (Wade 2006).

References

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

Frost, P. (2008). The beginnings of black slavery. Evo and Proud, January 25
http://evoandproud.blogspot.com/2008/01/beginnings-of-black-slavery.html

Frost, P. (2009). Skin color and Egyptian/Nubian encounters. Evo and Proud, April 23
http://evoandproud.blogspot.com/2009/04/skin-color-and-egyptiannubian.html

Hunwick, J.O. (2005). A region of the mind: Medieval Arab views of African geography and ethnography and their legacy. Sudanic Africa 16: 103-136
https://org.uib.no/smi/sa/16/16Hunwick.pdf

Lewis, B. (1990). Race and Slavery in the Middle East. Oxford University Press.

Thompson, L.A.  (1989). Romans and Blacks. Norman: University of Oklahoma Press.

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/

Wade, N. (2006). The twists and turns of history, and of DNA. The New York Times, March 12, Week in Review 14

Wallis Budge, E.A. (1907). The Paradise of the Holy Fathers. London: Chatto and Windus.
https://books.google.ca/books?id=LX_sCgAAQBAJ&printsec=frontcover&hl=fr&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Welsh, J. (2011). Still up for debate. LiveScience, November 9
https://www.livescience.com/16953-brain-body-size-expense.html 

Stumbling into the future

China's TFR before and after introduction of the one-child policy (Chaparro and Kulkarni 2015). Did that policy really change anything?



The European world has entered "demographic autumn"—on the one hand, fertility rates have fallen below replacement level; on the other, non-European immigration has risen progressively. These two trends can have only one outcome.

A similar demographic autumn is developing in East Asia. In some ways the situation is worse—fertility rates are at their lowest here. The record is held by the provinces of northeastern China, which have a total fertility rate of only 0.75 children per woman (Wang 2018). South Korea has an estimated TFR of 0.96, and a significant number of those births are to immigrant mothers from Southeast Asia (Haas 2018). Japan is doing better only by comparison, with a TFR of 1.4.

As for China as a whole, the rate is officially 1.6 and unofficially 1.05; the authorities revise this statistic upward to include second children who go unreported because they are illegal under the one-child policy (Wang 2018). That policy was scrapped in 2016, yet those second children still seem to be in hiding. Do they really exist? Did they ever? The Chinese government is stuck in a classic quandary: what do you do when you realize you've not been telling the truth?

The truth is that China’s TFR is half of what it needs to maintain its current population. This should be no surprise. In fact, it’s in line with what we see in Taiwan (1.1), in Singapore's Chinese community (1.1), and in Malaysia's Chinese community (1.3). Looking back, one can wonder whether the one-child policy ever had much impact on the TFR (Chaparro and Kulkarni 2015). The decline seems to have deep roots in modern Chinese society:

China faces an intractable and protracted demographic crisis driven by millions of individual family planning choices made by its increasingly wealthy and urbanized population. Policies restricting births imposed by the authorities have played only a contributing role in the drama. Similar aging trends can be seen throughout East Asia, especially in Japan, Taiwan and Hong Kong — territories that never had the types of legal restrictions imposed upon mainland Chinese couples.

[...] The current relaxation of family size restrictions is simply too little, too late. Before the policy was completely abolished in 2013, the Chinese government relaxed the one-child policy by allowing 11 million couples in which both spouses had no siblings to have two children. However, by May 2015, only 18 percent of eligible couples had taken advantage of the opportunity. This shows to what extent China's declining fertility is driven by personal considerations, as opposed to public policies.

In October 2015, the country's National Health and Family Planning Commission estimated that some 90 million families would qualify for the new, two-child policy. By the end of the year, however, only two million families had applied for permission to have a second child. China Daily conducted a survey in 2016 which showed that nearly 60 percent of working mothers do not want a second child, citing time and energy needed to raise it. Other concerns of the women included career risks, the pain of childbirth and little faith in their marriages. (O'Reilly 2019)

This problem is made worse by the gender imbalance: fewer girls than boys are being born. China now has 33 million more males than females. Finally, there is no reason to believe that the decline will stop at one child per woman.


Stumbling into the future

China's workforce is already shrinking, and the total population will begin to shrink before the mid-2020s.  The decline could be offset by pro-natalist measures. For instance, men and women could be encouraged to remain in rural areas and small towns, where conditions are better for family formation. To deal with the shrinking workforce, there could be measures to phase out low-paying jobs through automation and robotization. Of course, there must first be a willingness to act. Unfortunately, such willingness is far from evident, to judge by the current denial and inaction.

China will stumble into its demographic future, with one ad hoc solution after another. One of them may be immigration: "[China] currently hosts some 900,000 legal migrants and untold numbers of illegals, most of them factory workers from Vietnam. Also, desperate Chinese bachelors, unable to find Chinese mates because of the gender imbalance, are increasingly marrying Cambodian or Vietnamese women" (O'Reilly 2019). This is not to say that immigrants will be actively recruited. As is already the case, most will come illegally, being lured by jobs and empty housing. The onus will then be on the authorities to act—in the face of opposition not only from the business community but also from the migrants' home countries, many of which provide Chinese industry with valuable raw materials.

The solutions will ultimately depend on the ideological environment. Westerners often believe that the Chinese are intensely nationalist. In reality, there is a range of views within China, with the majority supporting civic nationalism. This is not coincidentally the view that the government promotes, partly out of conviction and partly to co-opt Tibetans, Muslims, and other minorities. Meanwhile, younger, university-educated people are moving toward the globalist consensus that reigns in the West.

One such person is Yinghong Cheng, who went abroad to study and is now a professor at Delaware State University. His latest book has a chapter titled "Racism and Its Agents in China" (Cheng 2019). In it he argues:

As an ideology, racism or racial discourses do not exist for their own sake or by themselves but always reflect power relations that may be addressed in other social hierarchy-based or identity-related discourses. In China today, racial thinking can appear in various discourses addressed to the political and ideological needs of the party-state, cultural and intellectual elites, and ordinary citizens: nationalism, patriotism, statism, social Darwinism, Han Chauvinism (or Hanism), non-Han ethno-nationalism, populism, and the Chinese civilizational supremacism in general (associated with the traditional ethnocentrism of China). (Cheng 2019, p. 241)

Elsewhere, he describes Hanism as “an ultra-ethnic supremacism” that “comes close to racism in its way of essentializing differences in a condescending manner” (Cheng 2019, p. 264). “The anti-Qing Hanist racism and a racial hierarchy of the world are the twin of the discourse of race in modern Chinese history. Like any other racial discourse in the world, they reflect power relations in reality but construct imaginary orders for a racially ideal—or “natural”—world” (Cheng 2019, p. 16). “… the Han political and intellectual elite exploited the social science disciplines of history, archaeology, and ethnology to establish the centrality of the Han blood and ancestors …” (Cheng 2019, p. 7).

Cheng overstates his case when he describes racism as an ideology that always reflects power relations. This is untrue if we examine its core value: preference for one’s kind. Throughout history and prehistory, humans have cared a lot about their kith and kin, even to the point of sacrificing their lives—and this has been no less true in simple societies with no elite or ruling class. Indeed, the oldest societies were essentially clans of related individuals. Furthermore, kinship is key not only to human life but also to the lives of organisms incapable of having ideas, let alone an ideology. 

Please note: I'm not arguing that kin preference is innate (although that argument can be made). I'm simply saying that it predates ideology and has long been the main organizing principle of society. Perhaps it's now obsolete. Perhaps it’s time for us to become self-defining individuals in a global marketplace. That’s the mainstream liberal argument. But that’s not Cheng's argument. He is arguing that kin preference always was wrong, and now we finally have a chance to get rid of it for good—by eliminating the "agents of racism." How this elimination is supposed to happen is not discussed. Indeed, he never applies to himself the sort of painstaking analysis he applies to others.

In all this, Cheng’s thinking is strangely ahistorical. If kinship has always been the basis for human society, perhaps there is a reason. Perhaps it has been the best way to organize social relations. Or perhaps not. Could we at least have a debate without being accused of base motives? Or being eliminated?

A big problem here is cargo-cult reverence for the West, and this reverence extends to the individualism and globalism that has become so dominant in North America and Western Europe, particularly in elite circles. Cheng denounces China for not doing enough to follow their example, while quoting Chinese writers who point to the resulting problems. If that model of society is already problematic in the West, where it has existed for a longer time, has deeper roots in the culture, and has greater chances for success, why should it do better in a country like China?

Cheng further reveals his ahistoricism when he argues that racism suits elite interests. Yes, it did back in the nineteenth and early twentieth centuries, when elites were nation-based. But they haven’t been that way for some time. Elites no longer have a national conscience, particularly in the West. Their self-interest now pushes them to liquidate the nation-state, notably by outsourcing jobs to low-wage countries and by insourcing low-wage labor for jobs that cannot be outsourced in construction, agriculture, and services. It is this two-way movement—and not "racism"—that is steadily increasing the Gini index, the most common measure of the gap between the rich and the poor.

Do China’s elites still have a national conscience? One can wonder. Unfortunately, this question goes unanswered in Cheng's book. Only nationalism is seen as problematic in the new China, and only nationalism is viewed as serving elite interests. Yet globalism, too, exists within a context of power relations. It, too, serves certain interests. 

As China's working population continues to shrink, will the elites push for higher wages so that labor may be used more sparingly? Or will they keep wages down by bringing in migrant labor? Which scenario is more likely if policymaking is in their hands? And which scenario will get better coverage in the Chinese media?


References

Chaparro, R. and K. Kulkarni. (2015). Does high population growth help or hurt economic development? Cases of China and Pakistan. International Journal of Education Economics and Development 6. 162. 10.1504/IJEED.2015.070629.
https://www.inderscienceonline.com/doi/abs/10.1504/IJEED.2015.070629

Cheng, Y. (2019). Discourses of Race and Rising China. Palgrave Macmillan
https://books.google.ca/books?id=ht-GDwAAQBAJ&printsec=frontcover&hl=fr&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Haas, B. (2018). South Korea's fertility rate set to hit record low of 0.96. The Guardian, September 3
https://www.theguardian.com/world/2018/sep/03/south-koreas-fertility-rate-set-to-hit-record-low

O'Reilly, B. (2019). China lacks the wherewithal to adjust to demographic decline. Austrian Economics Center
https://www.austriancenter.com/china-lacks-the-wherewithal-to-adjust-to-demographic-decline/

Wang, M. (2018). For Whom the Bell Tolls: A Retrospective and Predictive Study of Fertility Rates in China (November 8, 2018). Available at SSRN: 
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3234861 

The Golden Age of Intelligence?

Busts of Greek philosophers (Wikicommons, Matt Neale). Did the Ancient Greeks have the highest mean IQ of any human population then and since?



Francis Galton argued that average intelligence had been much higher in ancient Greece than in modern England. He came to this conclusion after comparing the proportion of eminent men in Athens of the fifth century BC with the proportion of eminent men in the England of his day:

It follows from all this, that the average ability of the Athenian race is, on the lowest possible estimate, very nearly two grades higher than our own-that is, about as much as our race is above that of the African negro.(Galton 1869, p. 342)

This high ability was then presumably lost:

We know, and may guess something more, of the reason why this marvellously-gifted race declined. Social morality grew exceedingly lax; marriage became unfashionable, and was avoided; many of the more ambitious and accomplished women were avowed courtesans, and consequently infertile, and the mothers of the incoming population were of a heterogeneous class. (Galton 1869, pp. 342-343)

If we accept Galton's reasoning, Ancient Greeks had the highest mean IQ of any human population, something like 120 or 125. By comparison, Ashkenazi Jews have an estimated mean IQ of 110. But was Galton right? His calculations were criticized at the time, specifically for underestimating the number of Athenian citizens. He consequently revised his calculation downward to 1.5 grades higher, i.e., a mean IQ of 115 to 119 (Challis 2013, p. 56).

That's still impressive. But higher IQ doesn't necessarily imply higher innate intelligence. Conditions in ancient Greece may have simply been better for intellectual discussion, such activity being respected as an activity in its own right. By comparison, intellectual discussion was much more circumscribed in the ancient Middle East, where it was confined to specific people who performed specific duties, most often writing and copying texts at the request of others.

Admittedly, this explanation does not exclude a genetic one. If the cultural environment favors intellectual development, it will tend to reward the most promising people with reproductive success. A scribe is thus praised in a Jewish wisdom book from the second century BC: "Many will praise his understanding; it will never be blotted out. His memory will not disappear, and his name will live through all generations. Nations will speak of his wisdom, and the congregation will proclaim his praise. If he lives long, he will leave a name greater than a thousand." Book of Sirach [39.1-11].

In the ancient world, 'leaving a great name' did not mean being written about by historians but rather having many illustrious children to carry on the family name long after death. Intellectual ability thus co-evolved with a supportive cultural base. Indeed, we humans have co-evolved much more with our cultural environment than with our natural environment (Hawks et al. 2007).


A new yardstick

Galton's conjecture can now be tested with two new research tools:

1. Ancient DNA. Large quantities of genetic data have been collected from ancient human remains and are now being made available to researchers. This year, the Reich lab at the Harvard Medical School released over 2,000 ancient genomes, including 30 from ancient Greece.

2. Polygenic cognitive score. Some gene loci are associated with differences in educational attainment. By examining the variants at these loci and by adding up the ones associated with higher educational attainment, we can calculate a polygenic score that correlates with mean IQ (r = 0.98).

By examining 102 ancient genomes, a research team led by Michael Woodley of Menie was able to chart the evolution of cognitive ability in Europe and Central Asia. His team found that genetic variants for higher educational attainment gradually increased in frequency from 4,560 to 1,210 years ago (Woodley of Menie et al. 2017). Now, with newly released data from the Reich lab, he is leading a research effort to look specifically at ancient Greeks. The results are still preliminary, but they indicate a progressive increase in the polygenic score from Neolithic to Mycenaean times, followed by a decrease. When? We don't know because we lack post-Mycenaean data (Woodley of Menie et al. 2019).


More to come ...

This is a promising avenue for research. In particular, we need:

- A larger sample of modern Greek genomes. This should not be difficult.

- Samples from post-Mycenaean times to the end of Ottoman rule. Was Galton right in placing this cognitive decline during the ensuing Hellenistic and Roman periods? Or did it happen over a longer span of time?

The final published paper should explain at greater length the research team's use of a restricted polygenic score, i.e., a polygenic score based only on those genetic variants that seem causally related to high educational attainment, and not simply associated with high educational attainment. This approach is acceptable if a third party had identified these variants; otherwise, there is a risk of focusing on those variants that support Galton's hypothesis.

Another point: in the presentation of his new project, Woodley of Menie spoke repeatedly about population replacement at various times in the history of ancient Greece (Woodley of Menie et al. 2019). Yet the current thinking is that immigration was historically unimportant in Greece. Present-day Greeks are largely descended from the Mycenaeans, with some later introgression by Slavic tribes and other peoples (Gibbons 2017; Stamatoyannopoulos et al. 2017).

This research is especially exciting because the Reich lab released ancient DNA data not only from ancient Greece but also from elsewhere. History may end up being seen in a new light. For instance:

- Rome probably went through a similar increase in mean intelligence, followed by decline. When did the decline begin? During the collapse of the fifth century? I suspect earlier, perhaps in the third century. The barbarian invasions were both a cause and effect in the collapse of Roman civilization.

- The Enlightenment was due only in part to things like the invention of the printing press, the voyages of discovery, and the founding of universities. These were subsidiary causes that resulted from and supported a more fundamental change: a steady increase in the smart fraction of European societies—the proportion of people who enjoy reading, writing and, above all, thinking.


References

Angel, J.L. (1950). Population size and microevolution in Greece. Cold Spring Harbor Symposia on Quantitative Biology 15: 343-351. doi:10.1101/SQB.1950.015.01.031

Challis, D. (2013). The Archaeology of Race. The Eugenic Ideas of Francis Galton and Flinders Petrie. London: Bloomsbury.
https://www.academia.edu/1520119/Archaeology_of_Race._The_Eugenic_Ideas_of_Francis_Galton_and_Flinders_Petrie_Bloomsbury_2013_ 

Galton, F. (1869). Hereditary Genius: An Inquiry into Its Laws and Consequences. London: MacMillan.
http://galton.org/books/hereditary-genius/

Gibbons, A. (2017). The Greeks really do have near-mythical origins, ancient DNA reveals. Science August 2
https://www.sciencemag.org/news/2017/08/greeks-really-do-have-near-mythical-origins-ancient-dna-reveals 

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.
https://www.researchgate.net/profile/Henry_Harpending/publication/5761823_Recent_Acceleration_of_Human_Adaptive_Evolution/links/0c9605240c4bb57b55000000.pdf  
Stamatoyannopoulos, G., A. Bose, A. Teodosiadis, F. Tsetsos, A. Plantinga, N. Psatha, N. Zogas, E. Yannaki, P. Zalloua, K.K. Kidd, B.L. Browning, J. Stamatoyannopoulos, P. Paschou, P. Drineas et al. (2017). Genetics of the peloponnesean populations and the theory of extinction of the medieval peloponnesean Greeks. European Journal of Human Genetics 25: 637-645.
https://www.nature.com/articles/ejhg201718 

Woodley of Menie, 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://www.cambridge.org/core/journals/twin-research-and-human-genetics/article/holocene-selection-for-variants-associated-with-general-cognitive-ability-comparing-ancient-and-modern-genomes/BF2A35F0D4F565757875287E59A1F534

Woodley of Menie, M.A., J. Delhez, M. Peñaherrera-Aguirre, and E.O.W. Kirkegaard. (2019). Cognitive archeogenetics of ancient and modern Greeks. London Conference on Intelligence 
https://www.youtube.com/watch?v=UES_tpDxz9A 

Why did brain size decrease after the Ice Age?

Nubians (Wikipedia). After the last ice age, brain size decreased in Europeans and East Asians. In western Europeans, this trend continued until some time before 1800. No decrease is observable in a large series of crania from Nubia.



In my latest paper I argue that northern hunting peoples were the first to break free from the cognitive straitjacket of hunting and gathering. Because women at northern latitudes had few opportunities for food gathering, they took on new, more cognitively demanding tasks, like garment making, needlework, weaving, leatherworking, pottery, and kiln operation. This increase in task complexity, led by women, provided these peoples and their descendants with the mental toolkit for later developments: farming, more complex technology and social organization, and an increasingly future-oriented culture (Frost 2019).

That paper left out a key piece of evidence. As these northern hunting peoples expanded southward into the temperate zone, they must have had excess mental capacity, especially the women, who were now redirected toward the cognitive demands of food gathering and, later, farming. Cognitive demand also decreased for men, who no longer had to store huge quantities of spatiotemporal information for tracking game and finding their way home. On the other hand, men put some of this excess mental capacity to new uses, by exploiting many of the technologies that women had pioneered.

So is there evidence of decreased cognitive demand after the last ice age? According to a study by Maciej Henneberg (1988), brain size steadily shrank from the Mesolithic to modern times, on the order of 9.9% for men and 17.4% for women. This is consistent with the reduction in cognitive demand being greater for women than for men.

Henneberg ignored the sex difference, preferring to attribute the decrease in brain size to a corresponding decrease in body size for both men and women. This explanation has been challenged by John Hawks, who reanalyzed Henneberg's data and showed that the decrease in body size explains only one-fifth to one-seventh of the one in brain size. He also showed that the declining ratio of brain size to body size did not affect all human populations. In fact, it can be securely demonstrated only for Europeans and Chinese. Indigenous southern Africans and Australians may have had similar declines, but the sample sizes are too small to conclude with certainty. No overall change is seen in the one case where we have a large cranial sample from a non-Eurasian population (Nubians):

A large series of crania from ancient Nubia covers the period from roughly 3400 years ago to 600 years ago [20, 21]. Samples show a slight trend toward decrease in the major length, breadth and height measurements from Iron Age (Meroitic, external cranial module 145.2) to Medieval (Christian, external cranial module 143.9) times, but the intermediate series of crania (X-Group, external cranial module 147.1) is somewhat larger in these dimensions than either of the other groups. In this context it would be misleading to speak of a reduction in cranial vault size in this region. (Hawks 2011)

A recent reversal

This trend reversed itself at some point in time, apparently before the 1800s. Jantz and Jantz (2016) and Jellinghaus et al. (2018) found an increase in brain size from at least 1800 in Germans and 1820 in white Americans. When I asked John Hawks, he attributed this reversal to improvements in nutrition and a reduction of childhood disease. That, too, was what I thought, initially.

But, then, the reversal would surely have been stronger in women than in men. If brain size had decreased twice as much in women, shouldn't the rebound have been twice as strong in women? Yet this is not what we see in the brain size of Americans born from 1820 to 1990: "Both sexes changed, but female change was less pronounced than male change" (Jantz and Jantz 2016).  In Germans born between 1800 and 1950, no clear sex difference was observable in the magnitude of this change over time (Jellinghaus et al. 2018).

Both Jantz and Jantz (2016) and Jellinghaus et al. (2018) are skeptical that these changes could be explained by improvement in nutrition or reduction of childhood disease. Infant mortality is a good proxy for both, and it did not begin to decline until circa 1900. At the very least, the increase in brain size should have accelerated during the twentieth century, yet it didn't (Jellinghaus et al. 2018).


Conclusion

Our knowledge on this subject comes largely from Maciej Henneberg, who concluded that brain size had decreased in all human populations and that this decrease continued into modern times. Both conclusions have been disproven. The decrease did not affect all human populations, and it had already reversed by 1800 in northern Europeans, as shown by two recent studies on white American and German samples. 

Perhaps the reason lies in changing patterns of natural selection. After the last ice age, northern hunting peoples had excess mental capacity, particularly the women. This excess capacity enabled them to create and exploit new and more complex social environments—farming, towns and cities, civilizations … It was still more than what was needed, however, and a long-term decline set in. Then, in early modern times, this decline reversed in western Europeans, and brain size once more began to increase. Why? Perhaps this is related to evidence, summarized in my last paper, that mean intelligence steadily rose in western European societies during late medieval and early modern times.

Hawks' study is the only comprehensive critique of Henneberg's work. Unfortunately, it has never appeared in a peer-reviewed journal. When asked why, he replied: "I did not feel it was necessary to pursue formal journal publication for this, because I did not think it fit well into the journals at the time." When asked why he had removed a post on that study from his weblog (it was put up in 2012 and taken down in 2017), he answered: "I used to have a section on my blog for research manuscripts that were in prep, but I decided to discontinue this as I became involved in more collaborative work."

Is there another reason? I can understand not publishing a post because other work is more pressing, but why delete an existing post? What made it less blogworthy by 2017?

The study in itself seems uncontroversial. Indeed, it leads to the amusing conclusion that European brains got smaller while Nubian brains remained unchanged. But talk about "smaller brains" can trigger some people, and John Hawks is already viewed with suspicion because of his work with Henry Harpending and Greg Cochran. Henry once told me—not long before his untimely death in 2016—about the mounting pressures he was facing to discontinue his research. Have similar pressures been brought to bear on John Hawks? One may wonder. The last three years have seen a remarkable escalation of deplatforming and outright violence in the name of "antiracism." When Steve Sailer (2019) charted the number of New York Times articles that mention the word "racism," he found that this number took off during the mid-decade, rising from 291 in 2011 to 2,353 in 2018. The mentions also changed qualitatively, becoming much more vociferous.

Today, John is a tenured professor, yet he is now much more reticent to say what he thinks than when he was a graduate student. His example should be sobering. The pressure to be "correct" doesn't end when you get tenure.


References

Frost, P. (2019). The Original Industrial Revolution. Did Cold Winters Select for Cognitive Ability? Psych 2019, 1(1), 166-181
https://doi.org/10.3390/psych1010012

Hawks, J. (2011). Selection for smaller brains in Holocene human evolution. arXiv:1102.5604 [q-bio.PE]
https://arxiv.org/abs/1102.5604 

Henneberg, M. (1988). Decrease of human skull size in the Holocene. Human Biology 60: 395-405.
https://www.jstor.org/stable/41464021

Jantz, R.L., and L.M. Jantz. (2016). The Remarkable Change in Euro-American Cranial Shape and Size, Human Biology 88(1), 56-64 
https://doi.org/10.13110/humanbiology.88.1.0056

Jellinghaus, K., H. Katharina, C. Hachmann, A. Prescher, M. Bohnert, and R. Jantz. (2018). Cranial secular change from the nineteenth to the twentieth century in modern German individuals compared to modern Euro-American individuals. International Journal of Legal Medicine 132: 1477-1484.
https://www.researchgate.net/profile/Michael_Bohnert/publication/323952852_Cranial_secular_change_from_the_nineteenth_to_the_twentieth_century_in_modern_German_individuals_compared_to_modern_Euro-American_individuals/links/5ab8dcdcaca2722b97cfe45f/Cranial-secular-change-from-the-nineteenth-to-the-twentieth-century-in-modern-German-individuals-compared-to-modern-Euro-American-individuals.pdf 

Sailer, S. (2019). Graphing the Great Awokening. May 28, The Unz Review
http://www.unz.com/isteve/graphing-the-great-awokening/  

The Original Industrial Revolution

Cro-Magnon woman (Wikicommons) – At northern latitudes, women had fewer opportunities for food gathering, so they were free to specialize in new and more cognitively demanding tasks, like garment making, needlework, weaving, leatherworking, pottery, and kiln operation.





I've published an article on the theory that cold Paleolithic winters selected for intelligence. This theory is often attributed to J. Philippe Rushton and Arthur Jensen but actually goes much further back. The article is open access (see link), and the abstract is provided below. Comments are welcome.




Rushton and Jensen argued that cognitive ability differs between human populations. But why are such differences expectable? Their answer: as modern humans spread out of Africa and into northern Eurasia, they entered colder and more seasonal climates that selected for the ability to plan ahead, in order to store food, make clothes, and build shelters for winter. This cold winter theory is supported by research on Paleolithic humans and recent hunter-gatherers. Tools become more diverse and complex as effective temperature decreases, apparently because food has to be obtained during limited periods and over large areas. There is also more storage of food and fuel and greater use of untended traps and snares. Finally, shelters have to be sturdier, and clothing more cold-resistant. The resulting cognitive demands are met primarily by women because the lack of opportunities for food gathering pushes them into more cognitively demanding tasks, like garment making, needlework, weaving, leatherworking, pottery, and kiln operation. The northern tier of Paleolithic Eurasia thus produced the "Original Industrial Revolution"—an explosion of creativity that preadapted its inhabitants for later developments, i.e., farming, more complex technology and social organization, and an increasingly future-oriented culture. Over time, these humans would spread south, replacing earlier populations that could less easily exploit the possibilities of the new cultural environment. As this environment developed further, it selected for further increases in cognitive ability. Indeed, mean intelligence seems to have risen during recorded history at temperate latitudes in Europe and East Asia. There is thus no unified theory for the evolution of human intelligence. A key stage was adaptation to cold winters during the Paleolithic, but much happened later.



Reference



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

https://doi.org/10.3390/psych1010012

They really are smart ... and other surprises

Rachela - Maurycy Gottlieb (1856-1879) (Wikicommons). Ashkenazi Jews have a higher incidence of genetic variants associated with high educational attainment.



Intelligence varies from one individual to the next, and most of this variance has genetic causes. But what, exactly, are these causes? Lots and lots of genes, it seems. To be precise, if we look at the genes that influence human intelligence, we find two things:

1. They are very numerous, numbering in the thousands.

2. In general, their variants differ slightly in their effects.

This shouldn't be surprising. Evolution proceeds by tinkering, i.e., by making little changes. Big changes tend to produce big side-effects, and most side-effects are deleterious. So the genetic capacity for intelligence differs among humans through small differences at thousands upon thousands of genes. Does it follow, then, that we cannot understand these differences by looking only at a few genes? Not necessarily. Each gene is like a weathervane. If you can get enough subjects from a human population, even a few genes will tell you the direction and strength of natural selection for intelligence. 

Davide Piffer began looking at these “weathervanes” six years ago. He gathered data from different human populations on ten SNPs (single nucleotide polymorphisms) whose genetic variants are associated with differences in intelligence, specifically differences in educational attainment. Then, for each population, he estimated its genetic capacity for intelligence by calculating a "polygenic score"—the number of genetic variants associated with higher educational attainment, out of a maximum of ten.

This score correlated with population IQ (r=0.90) and with PISA scores (r=0.84). It was highest in East Asians:

East Asians have the highest frequencies of alleles beneficial to educational attainment (39%) and consistently outperform other racial groups both within the US and around the world, in terms of educational variables such as completion of college degree or results on standardized tests of scholastic achievement. Europeans have slightly lower frequencies of educational attainment alleles (35.5%) and perform slightly worse in terms of educational attainment, compared to East Asians. On the other hand, Africans seem to be disadvantaged both with regards to their level of educational attainment in the US and around the world. Indeed, Africans have the lowest frequencies of alleles associated with educational attainment (16%). (Piffer 2013)

These results were considered preliminary. Thousands upon thousands of genes influence intelligence, and here we have only ten! Perhaps chance alone produced this geographic pattern. Over the next few years, as other researchers discovered more SNPs associated with educational attainment, Davide Piffer repeated his study with more of these weathervanes.

His latest study has just come out. It uses data on 2,411 SNPs, and the polygenic score correlates even higher with population IQ (r=0.98). The geographic pattern is the same, with East Asians scoring higher than Europeans, and with Africans scoring lower.


Yes, Jews really are smart

This time, however, the highest score was obtained for Ashkenazi Jews: 

This dataset included a sample of 145 Ashkenazi Jewish individuals. The IQ of Ashkenazi Jews has been estimated to be around 110 [34]. Remarkably, their EDU polygenic score was the highest in our sample, corresponding to a predicted score of about 108, mirroring preliminary results from a smaller (N = 53) sample (Dunkel et al., 2019) [34]. (Piffer 2019)

This finding vindicates the authors of a paper written more than a decade ago. Gregory Cochran, Jason Hardy, and Henry Harpending presented evidence that the mean IQ of Ashkenazi Jews exceeds not only that of non-Jewish Europeans but also that of other Jewish groups. The most striking piece of evidence is the high incidence among Ashkenazim of four genetic disorders: Tay-Sachs, Gaucher, Niemann-Pick, and mucolipidosis type IV (MLIV). All four affect the capacity to store sphingolipid compounds that promote the growth and branching of axons in the brain. These disorders are caused by alleles that are harmful in the homozygote state and beneficial in the much more common heterozygote state, i.e., the brain receives higher levels of sphingolipids without the adverse health effects.

Ironically, these facts are coming to light at a time when Ashkenazi Jews are disappearing through low fertility and high out-marriage. Meanwhile, and not coincidentally, they are disappearing from the ranks of top winners at the U.S. Math Olympiad, the Putnam Exam, the Computing Olympiad, and other academic competitions. This decline became noticeable in the 1980s and has accelerated since the turn of the millennium (Unz 2012; Frost 2018). Jews are still present in intellectual and cultural life, but this presence is losing its dynamism and becoming a mere legacy.


African American IQ is higher than predicted

The polygenic score seems to underpredict the IQ of African Americans:

Indeed, the IQ of African Americans appears to be higher than what is predicted by the PGS (Figure 2), which suggests this cannot be explained by European admixture alone, but it could be the result of enjoying better nutrition or education infrastructure compared to native Africans. Another explanation is heterosis ("hybrid vigor"), that is the increase in fitness observed in hybrid offspring thanks to the reduced expression of homozygous deleterious recessive alleles. (Piffer 2019)

I’d propose another possible explanation: higher intelligence in African Americans may be associated with a somewhat different basket of genetic variants. Some of these variants may come from our friends the Igbos, who seem to have followed their own evolutionary path toward higher intelligence (Frost 2015). Many notable African Americans are in fact of Igbo descent, including Forest Whitaker, Paul Robeson, and Blair Underwood (Wikipedia 2019).

Davide is skeptical about this explanation, pointing out that population IQ is in line with the polygenic score he calculated for sub-Saharan African groups (Esan, Gambians, Luhya, Mende, Yoruba). None of those groups, however, are Igbo, and it's really the Igbo who stand out among West Africans in measures of intellectual and educational attainment. If only for the sake of curiosity, we should find out their polygenic score. This score may underpredict their genetic capacity for intelligence, which to some degree would be boosted by genetic variants that exist only in sub-Saharan Africa, but it should still exceed what we see for other West Africans.


Conclusion

This latest study brings to 2,411 the number of SNPs that can inform us about the genetic capacity for intelligence in different human populations. This information was more dubious when only ten SNPs were available, and the geographic pattern could be put down to chance. That argument now seems weak. If chance is causing this pattern, why do we keep getting the same one?

Sure, we can wait until we get even more relevant SNPs, but the overall picture will probably remain the same. We will get finer geographic detail. In France, for example, we will probably understand why educational attainment is so much higher in Brittany (see:  http://www.targetmap.com/viewer.aspx?reportId=5987  H/T to Philippe Gouillou). There are probably several European regions and subregions where the genetic capacity for intelligence is on a par with what we see in Ashkenazi Jews and East Asians.

In sum, these findings deserve to be better known ... and more widely discussed.


Erratum

Initially, I wrote that Davide Piffer used 127 SNPs. In fact, 127 is the number of SNPs found in the HGDP (low coverage) dataset. In the other two datasets (1000 Genomes and GnomAd), those that the main analysis was based on, there were actually 2,411 SNPs.


**** Hiatus alert ****

I'll be unable to post for the near future, probably the next three months. 


References

Cochran, G., J. Hardy, and H. Harpending. (2006). Natural history of Ashkenazi intelligence, Journal of Biosocial Science 38: 659-693.
https://antville.org/static/sites/kratzbuerste/files/AshkenaziIQ.pdf   

Frost, P. (2018). The end of Jewish achievement? Evo and Proud, May 21
http://evoandproud.blogspot.com/2018/05/the-end-of-jewish-achievement.html

Frost, P. (2015). The Jews of West Africa, Evo and Proud, July 4
https://evoandproud.blogspot.com/2015/07/the-jews-of-west-africa.html

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://www.mdpi.com/2624-8611/1/1/5

Piffer, D. (2013). Factor analysis of population allele frequencies as a simple, novel method of detecting signals of recent polygenic selection: The example of educational attainment and IQ, Mankind Quarterly 54(2): 168-200
https://www.researchgate.net/profile/Davide_Piffer/publication/260436834_Factor_Analysis_of_Population_Allele_Frequencies_as_a_Simple_Novel_Method_of_Detecting_Signals_of_Recent_Polygenic_Selection_The_Example_of_Educational_Attainment_and_IQ/links/0c9605314d28dba7ea000000/Factor-Analysis-of-Population-Allele-Frequencies-as-a-Simple-Novel-Method-of-Detecting-Signals-of-Recent-Polygenic-Selection-The-Example-of-Educational-Attainment-and-IQ.pdf 

Unz, R. (2012). The myth of American meritocracy. The American Conservative, November 28
http://www.theamericanconservative.com/articles/the-myth-of-american-meritocracy/   

Wikipedia (2019). Igbo people.
https://en.wikipedia.org/wiki/Igbo_people#Diaspora

Autumn in China

Pink Autumn, by Victor Wang (2017) (Wikipedia). China’s demographic crisis is much worse than what official statistics let on.

With its population ageing as a result of longer lifespans and a dwindling number of children, the world's most populous nation decided in 2016 to allow all couples to have a second child, relaxing a tough one-child policy in place since 1978.

But birth rates plummeted for the second consecutive year last year. Policymakers now fret about the impact a long-term decline in births will have on the economy and its strained health and social services. (Stanway 2019)

The above Reuters article appeared two weeks ago. Although China lifted its one-child policy in 2016, its total fertility rate is still declining and now stands at 1.6 children per woman—well below the replacement level of 2.1 children. Delegates to China's parliament are saying that "radical steps are needed."

Are things that bad? No … they're worse. China's fertility rate is much lower than the official figure of 1.6 and probably close to what we see in Taiwan (1.1), in Singapore's Chinese community (1.1), and in Malaysia's Chinese community (1.3). Moreover, it is continuing to decline and will soon fall below the threshold of one child per woman, if it has not already done so. Finally, this very low fertility has lasted long enough to exhaust all population momentum. The population will soon begin to shrink, most likely five years earlier than the officially projected date of 2030. 

The real figures

The official figure of 1.6 children per woman is consistent with estimates by respected international bodies: 1.62 (World Bank, 2016); 1.8 (Population Reference Bureau, 2016); and 1.6 (United Nations, 2011-2015) (Wang 2018). The total fertility rate can also be estimated from data that China collects every year, i.e., the sample surveys taken by the National Bureau of Statistics. Using this source, Mengqiao Wang came up with much lower figures:

[…] far below the 2.1 replacement level, national TFR fluctuated around 1.4 since 2003, before dropping to around 1.2 since 2010 and finally reaching an astoundingly low value of 1.05 in 2015. (Wang 2018)

This pattern of very low fertility is limited to Han Chinese, particularly those in the northeastern provinces of Liaoning, Heilongjiang, and Jilin. In those provinces, the total fertility rate has fallen to 0.75 children per woman, and death rates have already overtaken birth rates:

Population shrinkage was already a fact for the northeastern part of the country, and it remained a question of when but not whether that fact would spread to other areas of the nation (official estimate of population peak at 1.45 billion by 2030 but unofficial estimate of 1.41 billion as earliest as 2025. (Wang 2018)

Why are these figures so much lower than the official figures? The main reason given is that the one-child policy caused widespread underreporting of births: many Chinese were having second children but not reporting them to government statisticians for fear of being penalized. This is seen in the differences between the raw data of the sample surveys and the official estimates of the National Bureau of Statistics. 

The NBS estimates, however, seem to be based on the sample survey data … with an upward adjustment to take underreporting of births into account: "Ironically, the NBS mentioned that the annual total births announced were calculated and inferred from the same sample surveys this study analyzed" (Wang 2018). So we are trapped in a circular argument: the sample surveys must be missing many births because the NBS estimates show a higher birth rate. But the same NBS estimates have been adjusted upwards because so many births are supposedly being missed.

Moreover, if the one-child policy had caused so much underreporting of births, the number of reported births should have increased in 2016, when that policy was scrapped, and that increase should have persisted in subsequent years. That's not what happened. The number of births did rise in 2016 and then fell in 2017 and 2018. The rise was probably due to some parents deciding to have a second child because there were no longer any financial penalties. The "backlog" of potential childbearing has now been cleared, and the fertility rate has returned to its pre-2016 slump.

It should be emphasized that the decline in Chinese fertility is now being driven by the growing number of women who have no children at all. This childlessness cannot be blamed on the one-child policy, and it is questionable, in fact, whether that policy has had much impact on the fertility rate for the past two decades. Total fertility rates have declined to the same very low level among Chinese people in Taiwan, Singapore, and Malaysia—where there has never been a one-child policy.

How bad is it?

Pretty bad. The fertility rate dropped below the replacement level in 1992 and has been at very low levels (1.4 or lower) since 2003. There is very little population momentum left, and an absolute drop in numbers should begin in the mid-2020s. Meanwhile, the total fertility rate may decline even further. In 2018, it was 0.98 in South Korea and 0.75 in northeastern China (Kyu-min and Su-ji 2019; Wang 2018). In all of East Asia, this pattern has only one exception: North Korea, where the rate is 1.98 children per woman (Wikipedia 2019). This is what we call “a failed state.”

One can always say that China has well over a billion people and can afford to shed a few hundred million. The relevant figure, however, is not the total population but rather the number of women who can bear children. That figure is a lot smaller and will continue to shrink. Women of childbearing age are defined (generously) as being 15 to 49 years old. Their numbers peaked at 383 million in 2011 and have been falling each year by 4 to 6 million. If we look at the most fertile age group (20-29), their numbers are expected to fall from 107.7 million in 2016 to around 80 million in 2020 (Wang 2018). 

There is no real precedent for what is happening. In the Western world, the fertility rate has declined over a longer time and has reached very low levels only in some countries, notably those of southern and eastern Europe. Moreover, unlike those countries China is still creating jobs at a high rate. Who will fill those jobs?

I addressed that question in a series of posts I wrote nine years ago. The abundance of jobs and empty housing will suck in immigrants from poorer countries, initially from Southeast Asia and then increasingly from South Asia and Africa. The African influx into Asia will be the big surprise of the 21st century, being especially noticeable in Malaysia and South China.

What can be done?

The first step toward solving a problem is to recognize that it exists. Most problems go unsolved because no one takes that first step. China is starting to move in that direction, but the word "starting" should be stressed. As Wang (2018) notes, there is a recurring tendency by the Chinese bureaucracy to downplay the demographic crisis. In some cases, the relevant data are not published:

Regrettably, such data for 2016 were no longer published in the most recent 2017 yearbook as the official publication mentioned that "In comparison with China Statistical Yearbook 2016, following revisions have been made in this new version in terms of the statistical contents and in editing: Of the chapter "Population", table named Age-specific Fertility Rate of Childbearing Women by Age of Mother and Birth Order is deleted." (China Statistical Yearbook 2017). Reasons were unknown for the deletion of this table, and it was unclear if the deletion would be temporary or permanent, or whether such deletion would continue in future years beyond 2016. (Wang 2018).

With determined effort, very low fertility can be reversed. Israel has gone the farthest in this direction, having achieved replacement fertility even among secular Jews. One must provide not only financial incentives but also cultural and ideological ones. Marriage and family formation must be seen positively. In this, unfortunately, the West is not an example to follow.

Wang (2018) suggests four measures to deal with the demographic crisis:

- Make demographic data fully accessible for debate and discussion.

- Eliminate controls on couples who want to have more than two children.

- Lower the minimum age for marriage, which is currently 22 for men and 20 for women.

- Allow out-of-wedlock births.

The first three measures seem sensible, although the second one would probably have little effect. Such controls are already absent in Taiwan, Singapore, and Malaysia. The last measure is terrible. All things being equal, a single mother will have fewer children than a married mother. Yes, a single mother can eventually marry or remarry, but such marriages tend to be less stable and thus less conducive to future childbearing, largely because the husband is less willing to support children that are not his own.

Of course, not all things are equal. Single mothers tend to be more present-oriented and, thus, more indifferent to the long-term costs of their actions, like those of having children. But what is to be gained by encouraging such people to reproduce? The experience of the West has been that single mothers, and their children, end up being a net cost to society.

In the West, the increase in single motherhood has coincided very closely with the decline in fertility, and both reflect the same underlying problem: people are less willing to commit to a long-term relationship and raise the children it produces. We increasingly live in a culture where the only valid entity is the individual. Everything else—family, community, nation—is illegitimate.

References

Frost, P. (2010a). China and interesting times ... Evo and Proud, February 25

http://evoandproud.blogspot.com/2010/02/china-and-interesting-times.html

Frost, P. (2010b). China and interesting times. Part II. Evo and Proud, March 4

http://evoandproud.blogspot.com/2010/03/china-and-interesting-times-part-ii.html 

Frost, P. (2010c). China and interesting times. Part III. Evo and Proud, March 11

http://evoandproud.blogspot.com/2010/03/china-and-interesting-times-part-iii.html 

Frost, P. (2010d). Has China come to the end of history? Evo and Proud, March 18

http://evoandproud.blogspot.com/2010/03/has-china-come-to-end-of-history.html

Kyu-min, C. and S. Su-ji. (2019). Fertility rate plummets to less than 1 child per woman. National Politics, February 28

http://english.chosun.com/site/data/html_dir/2019/02/28/2019022801617.html

Stanway, D. (2019). China lawmakers urge freeing up family planning as birth rates plunge. Reuters, March 12

https://ca.reuters.com/article/topNews/idCAKBN1QT0SM-OCATP

Wang, M. (2018). For Whom the Bell Tolls: A Retrospective and Predictive Study of Fertility Rates in China (November 8, 2018). Available at SSRN: https://ssrn.com/abstract=3234861

Wikipedia (2019). Demographics of North Korea.

https://en.wikipedia.org/wiki/Demographics_of_North_Korea#Size_and_growth_rate