The Sub-Saharan African Dental Complex

Map of Nigeria, showing the location of the Iwo Eleru rock shelter and the Iwo Eleru skulls. (Harvati et al., 2011)

Sub-Saharan Africans have an unusual complex of dental features:

[…] compared to other world populations, Africans south of the Sahara Desert are distinct dentally — especially in their expression of nine high- and two low-frequency morphological features. This suite of traits was termed the “Sub-Saharan African Dental Complex” (SSADC); it includes the world’s highest occurrences of Bushman canine, two-rooted UP1, UM1 Carabelli’s trait, three-rooted UM2, LM2 Y-groove, LM1 cusp 7, LP1 Tom’s root, two-rooted LM2, and UM3 presence, and among the lowest occurrences of UI1 double shoveling and UM1 enamel extension. (Irish, 2011)

The two low-frequency traits appear to be “derived.” They seem to have developed in sub-Saharan Africa after modern humans began to spread to other continents. The other traits, however, are ancestral:

[…] the same nine high-frequency traits are also ubiquitous in the dentitions of extinct hominids and many extinct and extant non-human primates

[…] The presence and, indeed, prevalence (see next section), of high-frequency Sub-Saharan dental traits in fossil and recent hominoids—some of which are probably direct ancestors of modern humans, suggests they have been around for a long time. (Irish, 1998, pp. 87-88)

In addition to these traits, Irish (1998) mentions a low-frequency trait that seems likewise ancestral and specific to sub-Saharan Africans:

A final ancestral feature found with some regularity in Sub-Saharan Africans, relative to other modern groups, is polydontia. Numerous cases of extra incisors, third premolars, and fourth molars have been noted […] In one study (Watters, 1962) the incidence reached 2.5-3% in several hundred west Africans; many of the extra teeth were fully formed and erupted. “Typical” mammals exhibit three incisors and four premolars (Jordan et al., 1992). Polydontia is also found in living non-human primates […] (Irish, 1998, p. 88)

Why are these ancestral traits much more common in sub-Saharan Africans than in other humans? There are several possible reasons. One is that non-Africans began as a small founder group and thus lost much of the dental variability that still characterizes Africans. Another reason might be that natural selection favored new forms of dentition outside Africa, perhaps as a response to new food sources or new ways of preparing food.

But there’s a third possible reason: archaic admixture. Just as modern humans mixed to some extent with Neanderthals in Europe and Denisovans in Asia, perhaps there was also mixture with archaic hominins in Africa, and perhaps this admixture introduced archaic dental features into present-day Africans.

But how could present-day Africans have archaic admixture? If modern humans originated in Africa, wouldn’t they have encountered archaic humans only in Europe and Asia?

Well, at first, modern humans did not occupy all of Africa. They were initially a small population somewhere in East Africa. Then, around 80,000 years ago, this population began to expand northward and eventually into Eurasia (Watson et al., 1997). Meanwhile, the same expansion was taking modern humans westward and southward into other parts of Africa.

Just whom exactly did these modern humans encounter during their expansion within Africa? Initially, they probably met hominins who looked the same but still lacked some of the mental rewiring that gave modern humans a competitive edge. These “almost-moderns” account for about 13% of the current sub-Saharan gene pool and may have been related to the Skhul-Qafzeh hominins who occupied the Middle East 120,000 to 80,000 years ago (Watson et al., 1997).

As modern humans spread further west and south within Africa, they encountered much more archaic hominins, and perhaps even lingering Homo erectus groups. About 2% of the modern African genome comes from an archaic population that split from ancestral modern humans some 700,000 years ago. This admixture is dated to about 35,000 years ago and may have occurred in Central Africa, since the level of admixture is highest in pygmy groups from that region (Hammer et al., 2011).

A more tangible sign of admixture is visible in a skull retrieved from the Iwo Eleru rock shelter, in southwestern Nigeria, and dated to approximately 16,300 BP:

Our analysis indicates that Iwo Eleru possesses neurocranial morphology intermediate in shape between archaic hominins (Neanderthals and Homo erectus) and modern humans. This morphology is outside the range of modern human variability in the PCA and CVA analyses, and is most similar to that shown by LPA individuals from Africa and the early anatomically modern specimens from Skhul and Qafzeh.

[… ] the transition to anatomical modernity in Africa was more complicated than previously thought, with late survival of “archaic” features and possibly deep population substructure in Africa during this time. (Harvati et al., 2011)

Then there is the Broken Hill skull, found near Kabwe, Zambia and dated to 110,000 BP (Bada et al., 1974). It looks for all the world like a Homo erectus. Textbooks generally try to raise it to Homo sapiens status or argue for an earlier dating. Recently, a late dating has been confirmed by Stringer (2011).

Interestingly, when Irish (2011) compared dentitions from west, central, east, and south Africa, ranging in age from the late Pleistocene to the mid-1950s, the early Holocene Kenyans and Tanzanians were the sample that had the fewest ancestral traits of the Sub-Saharan African Dental Complex (SSADC). In other words, the SSADC seems to have been least present in the “homeland” of modern humans (East Africa) and more present farther west and south.

Given the high level of archaic admixture in sub-Saharan Africans, we may have to revise downwards the estimate of 1 to 4% Neanderthal admixture in Eurasians. Yes, Eurasians are closer than sub-Saharan Africans to the Neanderthal genome. But is this discrepancy solely due to Neanderthal admixture in Eurasians? Could it also be due to Sub-Saharan Africans becoming further removed from the Neanderthal genome through admixture with other archaic groups?

The past may be a stranger country than previously thought. When farming villages began to form in the Middle East, there may still have been archaic hominins roaming over parts of western and southern Africa.

References

Bada, J.L., R.A. Schroeder, R. Protsch, & R. Berger. (1974). Concordance of Collagen-Based Radiocarbon and Aspartic-Acid Racemization Ages, Proceedings of the National Academy of Sciences (USA), 71, 914-917.

Hammer, M.F., A.E. Woerner, F.L. Mendez, J.C. Watkins, and J.D. Wall. (2011). Genetic evidence for archaic admixture in Africa, Proceedings of the National Academy of Science (USA), 108, 15123-15128, www.pnas.org/cgi/doi/10.1073/pnas.1109300108

Irish, J.D. (2011). Afridonty: the “Sub-Saharan African Dental Complex” revisited, American Journal of Physical Anthropology, 144(supp. 52), 174

Irish, J.D. (1998). Ancestral dental traits in recent Sub-Saharan Africans and the origins of modern humans, Journal of Human Evolution, 34, 81-98.

Harvati, K., C. Stringer, R. Grün, M. Aubert, P. Allsworth-Jones, C.A. Folorunso. (2011). The Later Stone Age Calvaria from Iwo Eleru, Nigeria: Morphology and Chronology. PLoS ONE 6(9): e24024. doi:10.1371/journal.pone.0024024
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0024024

Stringer, C. (2011). The chronological and evolutionary position of the Broken Hill cranium. American Journal of Physical Anthropology, 144(supp. 52), 287

Watson, E., P. Forster, M. Richards, and H-J. Bandelt. (1997). Mitochondrial footprints of human expansions in Africa, American Journal of Human Genetics, 61, 691-704.

Do classes become castes?

Relative frequencies of surnames of the rich and the poor (common criminals) 1236-1858. In England, there seems to have been much downward mobility among descendants of the medieval rich and some upward mobility among descendants of the medieval poor (Clark, 2010).
H/T to Jason Malloy

Henry Harpending (2012) argues that a meritocracy would become a caste society in a few generations:

Consider free meritocracy in a two-class system, meaning that for each generation anyone in the lower class who has greater merit than someone in the upper class immediately swaps class with them. Mating then occurs at random within class.

[…] Class mobility after the first generation is 30% while after four generations it has declined to 10% and continues to decline after that. The average merit in the two classes is about -1SD in the lower and +1SD in the upper on the original scale, corresponding to IQs of 85 and 115.

[…] after four generations, about 70% of the variance is between classes.

This model, however, contradicts what Clark (2009a) found in his historical study of surnames and social class in England. He first collected rare English surnames that were exclusive in the year 1600 to the rich (as represented by wealthy testators) or to the poor (as represented by common criminals). He then went forward in time to the year 1851 and determined the occupational profile of the same rare surnames:

How do the descendants of these two groups look in terms of socioeconomic status by 1851? Surprisingly there seems to be almost complete regression to the mean.

Between 1600 and 1851, there was apparently great downward mobility among descendants of the rich and modest upward mobility among descendants of the poor. Clark (2010) subsequently found that this regression held true for the entire period stretching from 1236 to 1858 (see above chart).

Why does this outcome diverge so much from the theoretical outcome described above? One reason is the assumption that marriage takes place only within each social class. Yet assortative mating is only a tendency, and exceptions are numerous. In post-medieval England, a widower would likely take a second wife of lower social status because of his disadvantaged position on the marriage market, given the care required for his existing children. It was also accepted for an upper-class man to marry a woman of lower rank, on the condition that she be beautiful. This phenomenon was noted by Darwin:

Many persons are convinced, as it appears to me with justice, that our aristocracy, including under this term all wealthy families in which primogeniture has long prevailed, from having chosen during many generations from all classes the more beautiful women as their wives, have become handsomer, according to the European standard, than the middle classes; yet the middle classes are placed under equally favourable conditions of life for the perfect development of the body. (Darwin, 1936 [1888], p. 892)

Another reason is downward mobility. In England, the upper and middle classes were reproductively more successful than the lower class until the late 19th century. But higher-class families could offer their children only a limited number of occupational slots. A certain proportion thus had to emigrate or move down the social ladder. The lower class was thereby continually replenished by the demographic overflow of the upper and middle classes.

Finally, the word “merit” has different meanings in different contexts. It is never just IQ. In post-medieval England, merit meant a mix of “middle-class” values: thrift, self-control, future time orientation, and rejection of violence as a way to settle disputes (Clark, 2007; Clark, 2009a; Clark, 2009b). In other societies, merit may involve a different mix of predispositions and personality traits, such as ruthlessness and willingness to use violence.

Yet caste societies do exist. How do they come about? The main precondition seems to be not only the existence of social classes, but also a monopoly on certain occupations by each class. In such circumstances, downwardly mobile individuals cannot compete with the existing lower class, since the latter’s livelihood remains off-limits.

Take Japan. That country had a social evolution similar to England’s, i.e., gradual demographic expansion of the middle class and, correspondingly, gradual demographic replacement of the lower classes by downwardly mobile individuals. But the lowest class, the Burakumin, survived because it had a monopoly on occupations that involved taking life or handling dead bodies (e.g., leather working, butchery, undertaking, etc.). The Burakumin thus survive as a remnant of the majority Japanese population that existed several centuries ago.

Stigmatized castes, like the Burakumin, may provide a window into a population’s evolutionary past. Such groups cannot participate in the gene-culture co-evolution of the majority population. Nor do they have much leeway for their own gene-culture co-evolution, since they are rigorously confined to a few occupations.

References

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

Clark, G. (2009a). The indicted and the wealthy: surnames, reproductive success, genetic selection and social class in pre-industrial England. http://www.econ.ucdavis.edu/faculty/gclark/Farewell%20to%20Alms/Clark%20-Surnames.pdf

Clark, G. (2009b). The domestication of Man: The social implications of Darwin. ArtefaCTos 2(1): 64-80.

Clark, G. (2010). Regression to mediocrity? Surnames and social mobility in England, 1200-2009
http://www.econ.ucdavis.edu/faculty/gclark/papers/Ruling%20Class%20-%20EJS%20version.pdf

Darwin, C. (1936) [1888]. The Descent of Man and Selection in relation to Sex. reprint of 2nd ed., The Modern Library, New York: Random House.

Harpending, H. (2012). Class, Caste, and Genes, West Hunter, January 13
http://westhunt.wordpress.com/2012/01/13/class-caste-and-genes/

African Americans and recent evolution

Fulani woman, Nigeria. Source.
African Americans aren’t just sub-Saharan Africans with European admixture. There has also been admixture from Amerindian peoples and from groups partly of North African origin, like the Fulani.

Have African Americans evolved since they first came to North America? The question may seem strange. Doesn’t evolution happen over millions of years? The first slaves disembarked in the future United States back in 1619 and the last ones arrived (illegally) in the 1850s. That’s about three centuries. How could any population evolve over so short a time?

Yet natural selection can cause significant change in as little as eight generations, at least in nonhuman species. In humans, it has altered at least 7% of the genome over the last 40 thousand years, and most of that change has happened over the last 10 thousand years (Hawks et al., 2007).

Jin et al. (2011) argue that African Americans have changed genetically over the last three centuries, not only through European admixture but also because of natural selection. First, many black slaves died during their passage from Africa to the New World. The survivors, already a select group, faced a new environment in colonial America. They had to adapt to new challenges in their struggle for existence, such as new pathogens, new social structures, and new means of subsistence.

To identify these effects of natural selection, Jin et al. (2011) used two methods on a large sample of African Americans (5,210 individuals). They first looked at various genomic regions to see whether the degree of European admixture was higher or lower than the admixture for the genome as a whole, estimated at 21.61%. Such deviations would be “signals” of natural selection favoring certain genetic variants at the expense of others.

The second method involved comparing the African component of the African American genome with the genomes of present-day sub-Saharan African populations—in proportion to their respective contributions to the African American gene pool.

And the results? Some genomic regions did deviate from the level of 21.61% European admixture. Many of them were associated with diseases, like prostate cancer and hypertension, that are more common among African Americans than among Euro Americans. Alleles that protect against malaria were also less frequent than would be predicted by European admixture. This is evidence that natural selection has been eliminating alleles that are less necessary in North America.

These results seem expectable. Too expectable, in fact. Yes, prostate cancer occurs more often in African Americans than in Africans, but this difference is due to underreporting and shorter life expectancy in Africa. Keep in mind that prostate cancer tends to be diagnosed late in life (Ogunbiyi & Shittu, 1999; Osegbe, 1997).

There are other grounds for skepticism. The deviations from overall European admixture were small, less than 2.6%. Admittedly, the sample size was large, so sampling error couldn’t be responsible. But there may have been other sources of error.

One of them concerns the estimated European admixture of 21.61%. This figure is consistent with previous estimates and is probably the best one available. But the degree of admixture varies among African Americans, especially by social class and by geographic region.

The authors also oversimplify their model when they describe African Americans as sub-Saharan Africans with European admixture. There has also been Amerindian admixture, as noted by Myrdal (1944, p. 124):

Indians were held as slaves in some of the American colonies while Negro slaves were being imported. Equality of social status between Indians and Negroes favored intermingling. The whites had little interest in hindering it. As the number of Negro slaves increased, the Indians slaves gradually disappeared into the larger Negro population. Whole tribes of Indians became untraceably lost in the Negro population of the South. […] Twenty-seven and three-tenths per cent of the Negro sample of 1,551 individuals examined by Herskovits claimed some Indian ancestry.

The authors state that they excluded African American individuals who had more than 2% Native American/East Asian ancestry, but such exclusion is at best approximate. And what about the many individuals with 1-2% Amerindian ancestry?

Another wild card is North African admixture. The Atlantic slave trade involved some populations that were partly of Arab/Berber descent, such as the Fulani (also known as Fulbe or Peul. The hotel maid who gave DSK a BJ was a Fulani). To some degree, North African admixture would resemble European admixture. To some degree, it would have its own characteristics.

Admittedly, these other admixtures were relatively small. But one doesn’t need a big factor to explain a deviation of two percent or so.

Ideas for future research

I’d like to see more research on recent evolution among African Americans, in particular on the possibility of gene-culture co-evolution. One cultural determinant of genetic change might be Christianity, specifically the way it has structured family life, turned men into active fathers, and created a strict rules-based culture.

Briefly put, I’d like answers to the following questions:

1. Was natural increase higher among church-going African Americans than among non-churchgoers? (because of a higher rate of family formation, stronger male involvement in the family, lower rate of infant mortality, etc.)

2. Did churchgoers have a different psychological profile than non-churchgoers? In other words, were non-churchgoers disproportionately made up of individuals who had trouble complying with a rules-based culture?

3. Did the higher natural increase of churchgoers, together with their psychological profile, lead to an evolutionary process similar to what Clark (2007) has described for England? (i.e., gradual demographic replacement of impulsive, present-oriented individuals with disciplined, future-oriented individuals).

4. Did this process abort in the 1960s with the decline in church life among African Americans?

References

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

Hawks J, Wang ET, Cochran GM, Harpending HC, Moyzis RK (2007). Recent acceleration of human adaptive evolution. Proc Natl Acad Sci USA, 104, 20753-20758.

Jin, W., S. Xu, H. Wang, Y. Yu, Y. Shen, B. Wu, & L. Jin (2011). Genome-wide detection of natural selection in African Americans pre-and post-admixture, Genome Research

Myrdal, G. (1944). An American Dilemma, Harper & Row, New York

Ogunbiyi, J. and Shittu, O. (1999). Increased incidence of prostate cancer in Nigerians. Journal of the National Medical Association, 3, 159-164.

Osegbe, D. (1997). Prostate cancer in Nigerians: facts and non-facts. Journal of Urology, 157, 1340.

Were Neanderthals furry?

What did the Neanderthals look like? Source
Hard to tell, since we know so little about their soft tissues. But they probably had fur.

Were the Neanderthals as furry as bears? The question was raised by one of my readers, and I’ll try to reply at length in this post.

There are three lines of argument:

Lack of tailored clothing

Neanderthal sites show no evidence of tools for making tailored clothing. There are only hide scrapers, which might have been used to make blankets or ponchos. This is in contrast to Upper Paleolithic (modern human) sites, which have an abundance of eyed bone needles and bone awls (Hoffecker, 2002, pp. 107, 109, 135, 252). Moreover, microwear analysis of Neanderthal hide scrapers shows that they were used only for the initial phases of hide preparation, and not for the more advanced phases of clothing production (Hoffecker, 2002, p. 107).

The counter-argument is that some human groups, notably the Yaghan of Tierra del Fuego, have lived in sub-arctic environments with little clothing.

Human body louse

The human body louse (which lives in clothing) seems to have diverged from the human head louse with the advent of modern humans. This dating is based on a comparison of the two louse genomes:

The results indicate greater diversity in African than non-African lice, suggesting an African origin of human lice. A molecular clock analysis indicates that body lice originated not more than about 72,000 ± 42,000 years ago; the mtDNA sequences also indicate a demographic expansion of body lice that correlates with the spread of modern humans out of Africa. These results suggest that clothing was a surprisingly recent innovation in human evolution.(Kittler et al., 2003)

A more recent analysis places the origin of body lice at 83,000 to 170,000 years ago (Toups et al, 2011). The authors conclude: “Our estimate for the origin of clothing use suggests that one of the technologies necessary for successful dispersal into colder climates was already available to AMH prior to their emergence out of Africa.”

There is nonetheless some controversy over the phylogenetic status of these two kinds of louse. Light et al. (2008) argue that there is far too much genetic overlap between them and that they cannot be considered “genetically distinct evolutionary units.” This point has been reiterated by Li et al. (2010):

While being phenotypically and physiologically different, human head and body lice are indistinguishable based on mitochondrial and nuclear genes. As protein-coding genes are too conserved to provide significant genetic diversity, we performed strain-typing of a large collection of human head and body lice using variable intergenic spacer sequences. Ninety-seven human lice were classified into ninety-six genotypes based on four intergenic spacer sequences. Genotypic and phylogenetic analyses using these sequences suggested that human head and body lice are still indistinguishable. We hypothesized that the phenotypic and physiological differences between human head and body lice are controlled by very limited mutations.

This is a recurring problem when one examines two species or subspecies that have recently diverged from each other. The only genes that have diverged are those whose variants clearly differ in adaptive value between the two environmental settings—in this case, head hair and clothing. It is only with time, and reproductive isolation, that differences will develop at other gene loci.

In the meantime, lice—like humans—exhibit the apparent contradiction of distinct phenotypic differences co-existing with very fuzzy genetic differences.

Finger bone ridges

A third reason is given by Cochran and Harpending (2009):

We don’t yet know for sure, but it seems likely that, as part of their adaptation to cold, Neanderthals were furry. Chimpanzees have ridges on their finger bones that stem from the way that they clutch their mother’s fur as infants. Modern humans don’t have these ridges, but Neanderthals do.

References

Cochran, G. & H. Harpending (2009). Neanderthals Steve Sailer’s iSteve Blog, January 10, 2009
http://isteve.blogspot.com/2009/01/neanderthals.html

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe. New Brunswick: Rutgers University Press.

Kittler, R., M. Kayser, & M. Stoneking. (2003). Molecular Evolution of Pediculus humanus and the Origin of Clothing, Current Biology, 13, 1414-1417.

Li, W., G. Ortiz, P-E. Fournier, G. Gimenez, D.L. Reed, B. Pittendrigh, D. Raoult. (2010) Genotyping of Human Lice Suggests Multiple Emergences of Body Lice from Local Head Louse Populations. PLoS Negl Trop Dis 4(3): e641.

Light, J.E.,M.A. Toups, & D.L. Reed. (2008). What’s in a name: The taxonomic status of human head and body lice, Molecular Phylogenetics and Evolution, 47, 1203-1216.

Toups, M.A., A. Kitchen, J.E. Light, & D.L. Reed. (2011). Origin of Clothing Lice Indicates Early Clothing Use by Anatomically Modern Humans in Africa, Molecular Biology and Evolution, 28, 29-32.

A few of my themes for 2012

Yakuzas (Japanese mafia). The largest Yakuza syndicate is over 70% Burakumin. Source

Here are a few themes I wish to write about during 2012:

Archaic admixture: A wild goose chase?

With the discovery that Europeans and Asians are 1 to 4% Neanderthal, there has been a rush to learn more. What genes are involved? Does this admixture explain why Eurasians are, well, hot stuff?

A few words of caution. The estimate of 1 to 4% is based on comparison of the Neanderthal genome with the modern Eurasian genome and the modern sub-Saharan African genome (Green et al., 2010). Neanderthals appear to be genetically closer to modern Eurasians than they are to modern sub-Saharan Africans. This increased closeness is therefore a measure of Neanderthal admixture in modern Eurasians. Right?

Well, not necessarily. It may also be a measure of non-Neanderthal admixture in modern sub-Saharan Africans. We now know that about 2% of the modern sub-Saharan African genome comes from a population that split from ancestral modern humans some 700,000 years ago (Hammer et al., 2011). Another 13% comes from archaics who were much closer to modern humans and probably related to the Skhul-Qafzeh hominins of the Middle East (Watson et al., 1997).

The figure of 1 to 4% Neanderthal admixture in modern Eurasians will thus have to be revised downward, just as our estimate of archaic admixture in modern sub-Saharans will have to be revised upward. This point has been made by Dienekes:

It is no longer tenable to propose that Eurasians are shifted towards Neandertals only because of Neandertal admixture: in fact some of the shift may be due to Africans being shifted away from Neandertals because of admixture with archaic African hominins.

However great or small Neanderthal admixture may be, can it explain why modern Eurasians are “hot stuff”? Doubtful. It’s true that both populations had to adapt to arctic environments, but they did so in very different ways. Neanderthals adapted to the cold through their morphology: thick body fat and dense fur. Modern Eurasians adapted by making tailored clothing and building insulated shelters.

Please don’t get me wrong. If you’re doing research on Neanderthal admixture, I wish you the best of luck. Perhaps you’ll find a thing or two. But don’t get your hopes up.


Whither North Korea?

Whenever an authoritarian leader dies, the door is opened to change, often radical change. The new leader is less able to command authority, and the chain of command itself is called into question at all levels. Pent-up pressure for change can finally be released. This was the case after the deaths of Franco in 1975, Mao Zedong in 1976, and Brezhnev in 1982. Here in my home province, it was the death of Duplessis in 1959 that ushered in the end of Quebec as a conservative Catholic society.

Will we see the same in North Korea? Will the death of Kim Jong Il lead to liberalization and, ultimately, reunification with South Korea?

Yes and no. North Korea will pursue its transition to a market economy. And this process is already making the population more independent-minded. As an observer in Pyongyang recently noted:

The women who daily set out their wares on the streets do so in defiance of police prohibitions. This is one of the clearest indications of the erosion of the regime’s control over its people. (The author observed many others, such as the men who openly smoked under “No Smoking” signs, the peasants who sim­ply ignored the traffic police and trundled their carts across intersections, and the people who—under the very eyes of the police—sat on the escalators in the Metro despite stern signs prohibiting this.) (Everard, 2011)

Private markets are also creating new spaces of social interaction that are independent of the State, and this trend will be assisted by the spread of cellphones and the strengthening of economic and social relations with China—itself a much more liberal society.

Finally, North Korea will drop all pretence of international socialism. This might seem to be just a matter of words—North Korea has long been a de facto nationalist regime—but semantics are important in the way people construct their perceived reality.

But, no, reunification is not in the cards, if only because the Chinese are adamantly opposed. There was a time in the 1990s when they were open to this idea. With reunification, U.S. troops would leave and Korea would become a more neutral country. It is now clear, however, that reunification has produced no such outcome in Germany. The Cold War may be over, but the U.S. still wants to have troops in mainland Eurasia, apparently as part of its geopolitical strategy.

So for now at least the Chinese will try to strengthen North Korea as a friendly buffer state. To this end, they will prod Pyongyang to pursue economic reforms and shed its pariah image, particularly by dismantling its nuclear program. In exchange, the Chinese may offer the protection of their own nuclear umbrella, as well as full membership in the Shanghai Cooperation Organisation (SCO).

It’s also unlikely that liberalization will lead to North Korea becoming more Westernized and Americanized. By “liberalization,” I mean the right of people to live their lives according to their own values—and not those imposed by the State or by a globalist elite. Hence, the Arab Spring has brought the triumph of Islamist political parties who promise to introduce stricter adherence to Shariah law. This has been a surprise to Western observers, but it should not have been.

The Burakumin

Although Japanese society is often seen as being very homogeneous, it does have a distinct class called the Burakumin who were officially outcastes until 1871 and are still widely looked down upon. They seem to descend from Japanese who held stigmatized occupations that involved the taking of life or contact with dead bodies, like butchery, leather making, and preparation of corpses for burial. Today, despite many remedial efforts, an academic gap persists between the Burakumin and other Japanese:

According to research on Buraku pupil/students' scholastic ability conducted in the post-war period, nearly 1 standard deviation difference in achievement scores was found between Burakumin and non-Burakumin pupil/students regardless of when and where the research was conducted. This meta-analysis on Buraku pupil/students' scholastic ability leads us to conclude that the relative difference in scholastic achievements between the Burakumin and non-Burakumin pupil/student has been maintained to a considerable degree through the post-war period. (BLHRRI, 1997)

In 2012, I will try to shed new light on this question by applying Greg Clark’s model. Clark (2007) argued that the English gene pool in 1800 was quite different from what it had been only a few centuries earlier. Over the years, the English middle class had expanded demographically and, through downward mobility, had largely replaced the English lower classes. I will suggest that Japan followed a similar evolution but with an interesting twist. As outcastes with a monopoly on certain occupations, the Burakumin were spared this demographic replacement. They may thus represent the Japanese population as it existed several centuries ago.

References

BLHRRI (1997). Practice of Dowa Education Today, Buraku Liberation and Human Rights Institute.
http://blhrri.org/blhrri_e/dowaeducation/de_0006.htm

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

Dienekes. (2011). Neanderthal admixture. Why I remain skeptical, December 19, 2011.
http://dienekes.blogspot.com/2011/12/neandertal-admixture-why-i-remain.html

Everard, J. (2011). The markets of Pyongyang, Korea Economic Institute, Academic Paper Series, 6(1), 1-7.
http://www.keia.org/publication/markets-pyongyang

Green, R.E., J. Krause, A.W. Briggs, T. Maricic, U. Stenzel, M. Kircher, et al. (2010). A draft sequence of the Neandertal genome, Science, 328, 710-722.
http://www.sciencemag.org/cgi/reprint/328/5979/710.pdf

Hammer, M.F., A.E. Woerner, F.L. Mendez, J.C. Watkins, and J.D. Wall. (2011). Genetic evidence for archaic admixture in Africa, Proceedings of the National Academy of Science (USA), early edition, www.pnas.org/cgi/doi/10.1073/pnas.1109300108

Watson, E., P. Forster, M. Richards, and H-J. Bandelt. (1997). Mitochondrial footprints of human expansions in Africa, American Journal of Human Genetics, 61, 691-704.

2012. A year of turbulence?

Child making Nike shoes (source). Western business now has access to labor under conditions not seen since the days of Charles Dickens.

My predictions from last year:

It won’t be such a bad year. Stock markets will reach record highs and pundits will say we’ve entered a sustained boom. For many people, life will never again be so good as it will be this year.

The main worry will be price rises for many commodities. With a return to even modest rates of economic growth, demand will outstrip supply in several areas. Talk of “peak oil” will be joined by concerns over “peak food” and “peak water.” Serious water shortages will hit the American southwest and southeast.

Well, the stock markets have not reached record highs. And there have been no serious water shortages, largely because of an unusually wet winter.

But food prices have been rising ominously. It was this factor that triggered the “Arab Spring” and is now fueling discontent in Russia. Also, for a lot of people—especially our elites—life has never been so good. We are into an economic recovery, of sorts.

How long will the recovery last? Perhaps another twenty years if it were a normal one. But it isn’t. The last recession was not allowed to finish its job of purging the economy. A lot of corporate flab was spared the axe, and dysfunctional attitudes toward debt are still common, particularly among consumers. In addition, the recovery is heavily dependent on government spending and consumer debt, and there is no indication that the economy is ready to go “cold turkey.” We may need more and more of the same stimulus just to maintain sluggish growth.

This debt crisis comes on top of a looming commodity crisis. Prices for fuel, food, housing, and other basics are being pushed up by the new buying power of Asian consumers and by immigration to North America and Western Europe. Can supply be increased to meet the rising demand? Yes, of course. Don’t worry. Everything will be fine—say the business interests that profit from this spike in demand.

Finally, we are facing a globalization crisis. On the one hand, jobs are being outsourced to lower-wage countries. On the other, lower-wage labor is being insourced. The result? A steady downward leveling of incomes throughout the Western World, except for the very rich. The latter now have access to labor under conditions not seen since the days of Charles Dickens.

The current recovery might nonetheless go on indefinitely. The Japanese, for instance, have kept their economy afloat for the past two decades by piling up massive debt. But they are just one society, and it’s one with a strong sense of social cohesion. In contrast, the Western World is very fractious, as seen by the bickering within the European Union. These social and political divisions will probably abort the recovery long before the possibilities for debt financing and money printing have been completely exhausted. And so much the better.

If I have to make a prediction for 2012, it will be that the recovery will continue—on life support, so to speak—but will run into increasing social turbulence. The ‘Arab spring’ will start to play out in the Western World as the elites begin to lose their legitimacy. This process is already under way in Europe, and we may see a domino effect where change in one country facilitates change in other countries.

My research interests

There have been some developments in my areas of research interest.

Skin color and face recognition

Natural selection tends to hardwire recognition of objects that regularly appear in our visual environment. One such object is the human face. As shown by Zhu et al. (2009) through a twin study, the ability to recognize faces is innate and not learned. This heritability is further shown by the two extremes of prosopagnosics and “super-recognizers.” The former cannot recognize faces better than any other object, whereas the latter have exceptional face recognition ability (Russell, Chatterjee, & Nakayama, in press; Russell, Duchaine, & Nakayama, 2009).

The American psychologist Richard Russell has recently shown that face recognition equally uses face shape and facial skin color:

Shape and pigmentation cues were used in roughly equal measure by people with very good and very bad face recognition ability. […] People who are good at recognizing faces are good at using both shape and pigmentation cues to do so; people who are bad at recognizing faces are bad at using both shape and pigmentation cues to do so (Russell, Chatterjee, & Nakayama, in press).

This mental processing of skin color seems to take place in a lower-level module whose output then feeds into the face-recognition module.

Neural circuits related to face recognition ability must use both shape and pigmentation information about equally. This supports the idea that these circuits represent facial appearance by pooling lower-level patterns of shape and reflectance into combinations that include both types of information (Jiang, et al., 2006). Further, this is consistent with the notion that the location of the Fusiform Face Area is midway along the shape–reflectance gradient in ventral cortex (Cant & Goodale, 2011) because the region integrates these two kinds of cues to visually process faces. (Russell, Chatterjee, & Nakayama, in press)

Dumouchel et al. (2010) have likewise concluded that face shape and “skin properties” are the main clues for face recognition, even more so than the relative distances of facial features from each other.

Why does skin color matter so much for face recognition? Didn’t our ancestors evolve in a context where people interacted only with their own kind or with neighboring groups of similar appearance? Yes, but there was another source of variation in skin color—gender and age. Women and young infants are paler, having less melanin and hemoglobin in their skin. Men, in contrast, are ruddier and browner.

We are thus innately sensitive to differences in skin color, but this sensitivity didn’t evolve in response to ethnic differences. It evolved in response to much smaller gender and age differences (Frost, 2010; Frost, 2011; van den Berghe & Frost, 1986).

At present, two research teams have the means and motivation to pursue this line of research: Richard Russell’s team at Gettysburg College and Frédéric Gosselin’s team at the Université de Montréal. We’ll probably see more findings by both teams over the next year.

The puzzle of European hair and eye colors

European populations have an unusually broad palette of hair and eye colors. This diversity doesn’t have a common genetic cause. It is due to a proliferation of alleles at two separate genes: MC1R for hair color and OCA2 for eye color. This proliferation did not come about through relaxation of selection for dark skin as ancestral Europeans moved into higher latitudes. Most of the new alleles have little or no affect on skin color, and in any case the timeframe is too narrow for this evolutionary scenario.

A likelier cause is sexual selection, which favors bright or novel colors that catch the attention of potential mates. If sexual selection is strong enough, a polymorphism of color variants may develop. A new color appears through mutation and, depending on its brightness or novelty, steadily rises in frequency until it is as common as the established color. Over time, these variants will increase in number. Humans have the potential for this kind of frequency-dependent sexual selection, e.g., darker-haired women are sexually preferred to the extent that they are less common. Such selection is consistent with the high number of alleles for hair color and eye color in European populations, the high ratio of nonsynonymous to synonymous variants among these alleles, and the relatively short time over which this hair and eye color diversity developed.

Sexual selection occurs when too many of one sex must compete for too few of the other. Among early modern humans, such imbalances resulted from (1) polygyny (to the degree that women could provide for themselves and their children without male assistance) and/or (2) higher mortality among men than among women (to the degree that men covered longer distances while hunting or changing camp). Wherever the polygyny rate was low and male mortality high, the result was strong sexual selection of women. Such selection was particularly strong on continental steppe-tundra, where men had to provide almost all of the food by hunting migratory game animals over long distances. Although this type of environment is now fragmentary, it covered until 10,000 years ago a much larger territory that matches the current range of European hair and eye color diversity (Frost, 2006).

This hypothesis would predict some degree of sex linkage among European alleles for hair and eye color, since the sexual selection was acting on women. Over time, there would have arisen alleles that produce non-black hair and non-brown eyes more so in women than in men, and these alleles would have gradually replaced their non-sex-linked counterparts. This process should not have gone very far, though, because of the narrow timeframe.

This prediction is borne out by a twin study on the genetics of hair color. Shekar et al. (2008) found that the women had lighter hair on average than the men and a higher proportion of red hair. Hair color was also more diverse in the women than in the men:

Females had, on average, lighter hair, on the A650t scale, than males.

[…] The correlation within brother–sister twin pairs was significantly lower than the correlation within brother–brother and sister–sister dizygotic twin pairs (P ≈ 0.01). This suggests that there may be qualitative differences in the genetic influences on the A650t index between sexes.

[…] Additive genetic influences explain 55% and 58% of variation in the A650t index within females and males, respectively. The additive genetic influence on the A650t index in males was, predominantly, qualitatively different from those that influence the index in females.

[…] Females had, on average, redder hair (P < 0.00001) and greater variation in R index scores (P _ 0.001) than males.

The sexual selection hypothesis would also predict that this evolutionary change took place over a relatively short time, specifically the last ice age 25,000 to 10,000 years ago and well after the entry of modern humans into Europe some 35,000 to 40,000 years ago. Is this prediction supported by evidence?

At present, no one is trying to date the diversification of European hair and eye colors.
The closest research effort would be the work by Norton and Hammer (2007) showing that Europeans became white-skinned long after their entry into Europe. Heather Norton is now trying to get a firm date on this phenotypic change.

References

Dupuis-Roy, N., I. Fortin, D. Fiset, and F. Gosselin. (2009). Uncovering gender discrimination cues in a realistic setting. Journal of Vision, 9(2), 10, 1–8.
http://journalofvision.org/9/2/10/, doi:10.1167/9.2.10.

Frost (2011). Hue and luminosity of human skin: a visual cue for gender recognition and other mental tasks, Human Ethology Bulletin, 26(2), 25-34.

http://media.anthro.univie.ac.at/ISHE/index.php/bulletin/bulletin-contents

Frost, P. (2010). Femmes claires, hommes foncés. Les racines oubliées du colorisme, Quebec City: Presses de l’Université Laval.

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103 http://www.sciencedirect.com/science/journal/10905138

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

Russell, R., G. Chatterjee, and K. Nakayama. (In press) Developmental prosopagnosia and super-recognition: no special role for surface reflectance processing. Neuropsychologia

Russell, R., B. Duchaine, and K. Nakayama. (2009). Super-recognizers: People with extraordinary face recognition ability. Psychonomic Bulletin & Review, 16(2), 252-257.

Shekar, S.N., D.L. Duffy, T. Frudakis, G.W. Montgomery, M.R. James, R.A. Sturm, & N.G. Martin (2008). Spectrophotometric methods for quantifying pigmentation in human hair—Influence of MC1R genotype and environment, Photochemistry and Photobiology, 84, 719–726.

Taschereau-Dumouchel, V., B. Rossion, P.G. Schyns, and F. Gosselin. (2010). Interattribute Distances do not Represent the Identity of Real World Faces, Front Psychol, 1, 159.

van den Berghe, P. L. & P. Frost. (1986). Skin color preference, sexual dimorphism, and sexual selection: A case of gene-culture co-evolution? Ethnic and Racial Studies, 9, 87-113.

Zhu, Q., Y. Song, S. Hu, X. Li, M. Tian, Z. Zhen, Q. Dong, N. Kanwisher, and J. Liu. (2009). Heritability of the specific cognitive ability of face perception, Current Biology, 20, 137-142.

Suicide and Inuit youth

Canadian suicide rates (per 100,000 people): Inuit, First Nations, all Canadians. Source

From Alaska to Greenland, young Inuit have unusually high rates of suicide, attempted suicide, and suicidal ideation. According to a 1972 survey of Inuit 15 to 24 years old from northern Quebec, 28% of the males and 25% of the females had attempted suicide (Kirmayer et al., 1998). Before the 1970s, suicide was rare among Inuit youth. Today, it has reached epidemic proportions.

Public authorities have responded largely by targeting those factors, like alcohol and drug abuse, that make it easier to go from thinking about suicide to actually doing it. While these efforts are having some success, there still remains the problem of suicidal ideation.

Why do so many Inuit youth contemplate suicide? Kirmayer et al. (1998) point to a prevailing sense of uselessness:

Inuit youth are confronted with the values of an individualistic, consumption-oriented society through mass media but have few opportunities to achieve the life-style portrayed. The result may be a sense of frustration, limited options, and difficulty imagining an optimistic future. This may extend to an impaired sense of self-continuity that contributes to attempted suicide.

Dufour (1994) argues that Inuit society has a long tradition of people ending their lives when they feel they have become useless. In the past, however, this kind of suicide involved only the elderly:

Suicide in early Inuit society was viewed positively when the individual had become a burden for the group. “Senilicide” in particular was deemed to be acceptable and appropriate. Its pattern: a usually elderly person motivated by illness, helplessness, bereavement, dependence on the group, famine, or resource shortage who would decide after consulting family members who sometimes could be called upon to assist. In contemporary Inuit society, the elderly no longer commit suicide. The young people do.

TV and video present young Inuit with an affluent lifestyle that is unattainable for all but a few. Meanwhile, school presents learning goals and standards of behavior that are likewise difficult to attain, especially for boys. By postponing adulthood in order to extend the learning process, school also has the unintended effect of humiliating Inuit youth. In another age, they were treated as young adults, often being parents in their own right. Today, they are just “children.”

Many young Inuit thus perceive themselves as being socially useless. And this self-perception is triggering suicidal ideation.

Such ideation may seem irrational from an individualistic Western standpoint. You cannot make your life better by ending it. Yet it is less irrational from the standpoint of one’s kin group, especially in a context of limited resources. Such was the case with elderly Inuit who would choose death so as not to burden the younger members of their band, such people being close relatives for the most part.

In such a context, natural selection—specifically kin selection—might have favored suicide as a response to perceived uselessness. Such selection is possible. Suicidal ideation is significantly heritable and seems to be inherited as a specific behavioral response:

Suicidal behavior is highly familial, and on the basis of twin and adoption studies, heritable as well. Both completed and attempted suicide form part of the clinical phenotype that is familially transmitted, as rates of suicide attempt are elevated in the family members of suicide completers, and completion rates are elevated in the family members of attempters. A family history of suicidal behavior is associated with suicidal behavior in the proband, even after adjusting for presence of psychiatric disorders in the proband and family, indicating transmission of attempt that is distinct from family transmission of psychiatric disorder. (Brent & Mann, 2005)

According to a twin study using American subjects, suicidal ideation has 36% heritability and suicide attempt 17% heritability (Fu et al., 2002).

De Catanzaro (1991, 1995) has argued that suicidal ideation has evolved as a response to a situation where an individual has become a burden to immediate kin. In studies of the general public and high-risk groups (elderly and psychiatric patients), he found that the strongest correlate of suicidal ideation was burdensomeness to family and, for males, lack of heterosexual activity. As Buss (1999, p. 94) concludes: “If a person is a burden to his or her family, for example, then the kin’s reproduction, and hence the person’s own fitness might suffer as a result of his or her survival.”

The threshold for suicidal ideation may be lower in some human populations than in others, depending on one’s risk of becoming a serious burden on kinfolk. This risk is high in Arctic hunting bands because their members are almost entirely close kin and because their nomadic lifestyle limits food storage for lean times. When food is scarce, who eats and who doesn’t? The question is especially difficult because close kin are involved. The easiest solution, in terms of keeping the peace and maintaining group cohesion, is one where the burdensome individual voluntarily bows out.

What does all of this mean for young Inuit who are thinking of suicide? Clearly, it is not enough to focus on things that facilitate the transition from suicidal ideation to actual suicide. That approach might work in southern Canada, where suicide tends to result from transient episodes that push people up and over the threshold of suicidal ideation. Among the Inuit, the threshold seems to be lower and the focus should be more on preventing ideation, specifically by giving young Inuit a greater feeling of self-worth and social usefulness.

References

Brent, D.A. & J.J. Mann. (2005). Family genetic studies, suicide, and suicidal behavior, American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 133C, 13-24.

Buss, D.M. (1999). Evolutionary Psychology. The New Science of the Mind, Boston: Allyn and Bacon.

de Catanzaro, D. (1991). Evolutionary limits to self-preservation, Ethology and Sociobiology, 12, 13-28.

de Catanzaro, D. (1995). Reproductive status, family interactions, and suicidal ideation: Surveys of the general public and high-risk group, Ethology and Sociobiology, 16, 385-394.

Dufour, R. (1994). Pistes de recherche sur les sens du suicide des adolescents inuit, Santé mentale au Québec, 19, 145-162.

Fu, Q., A.C. Heath, K.K. Bucholz, E.C. Nelson, A.L. Glowinski, J. Goldberg, M.J. Lyons, M.T. Tsuang, T. Jacob, M.R. True & S.A. Eisen. (2002). A twin study of genetic and environmental influences on suicidality in men, Psychological Medicine, 32, 11-24.

Kirmayer, L.J., L.J. Boothroyd, S. Hodgins (1998). Attempted Suicide among Inuit youth: Psychosocial correlates and implications for prevention, Canadian Journal of Psychiatry, 43, 816–822.