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/