A bird in a gilded cage

My second ebook has been published in the online journal Open Behavioral Genetics.

PDF version   Epub version
The following is a copy of the Foreword:
 

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Luigi Luca Cavalli-Sforza is a complex figure. On the one hand, he has publicly backed those who assert that human races do not exist. On the other hand, by aggregating large volumes of genetic data, he has proven the existence of large continental races, as well as smaller regional and micro ones. By developing the theory of gene-culture co-evolution, he has also shown that humans did not stop evolving genetically when they began to evolve culturally. In fact, the two processes have fed into each other, with humans having to adapt not only to the natural portion of their environment (climate, vegetation, wildlife, etc.) but also to the portion they themselves have created (mode of subsistence, behavioral norms, gender roles, class structure, belief system, etc.).

This has led some to see a double game at work. While bowing to the mainstream taboos, Cavalli-Sforza has quietly amassed evidence that human races not only exist but also differ in ways that are more than skin deep. In time, his weighty tomes will speak louder than his official statements on race. This may indeed be how he sees himself, and it might explain certain contradictions between his public persona and his academic self. Oh, those naïve antiracists, if only they knew how they’re being outfoxed!

Time will tell who is outfoxing whom. To date, the results speak for themselves. When in 1994 Cavalli-Sforza published The History and Geography of Human Genes, academics and non-academics alike were talking more openly about race, as seen by the publication the same year of The Bell Curve and by the willingness of previously silent anthropologists, like Vincent Sarich, to step forward and speak out. That interval of glasnost soon ended, in no small part because of Cavalli-Sforza’s apparent conversion, as attested in his book, to the view that human races do not exist in any meaningful sense.

Why did he convert? And did he really? I doubt there was any conversion. His change of heart was too rapid, and it happened while the zeitgeist was moving in the other direction. Perhaps he saw a chance to gain acceptance for his new tome. Or perhaps he received a letter one day, detailing his wartime record, the people he worked with, and the testing on human subjects …

Cavalli-Sforza had to remake his life when the war ended. He never denied the nature of his wartime research (the time it takes for anthrax to kill its host) but tried to create the impression that he had been doing pure research with no military implications. Yet this was Berlin, in 1943-1944. There was no money for pure research. Was he motivated by opportunism, the chance to gain experience in his field of study? Or did he feel loyalty to the Axis cause? It is difficult to say, and perhaps it doesn’t matter. It is enough to say that he later saw his wartime research as a stain on his record and tried to minimize it as much as possible. He was thus vulnerable to blackmail, or rather to his chronic fear of blackmail.

We will probably never know the full story. One thing is sure. If Cavalli-Sforza is playing a double game, he has been playing it far too long. Such a strategy is excusable for an academic who is young, untenured, poorly known, and far from retirement, but these excuses hardly apply to a professor emeritus like Cavalli-Sforza. The time is overdue to speak frankly and, if need be, pay the price. Anyway, what else can he do now with all of his public esteem? Take it with him to the next world?

 

References

Frost, P. (2014). L.L. Cavalli-Sforza. A bird in a gilded cage, Open Behavioral Genetics, March 28

http://openpsych.net/OBG/2014/03/l-l-cavalli-sforza-a-bird-in-a-gilded-cage/

https://www.dropbox.com/s/ryrtizfdqo9vc0o/A%20bird%20in%20a%20gilded%20cage%20-%20Peter%20Frost.epub

 

Kinder, gentler speech

 

A highwayman - by Glen Campbell (source). Before the rise of the State, and its pacification of social relations, the top man was the one who dominated the local group through a mixture of violence, bombast, and charisma.

 

Before the State came into being, men were organized into small, loosely defined groups where authority was wielded through a mixture of violence, bombast, and charisma. The more you had of these qualities, the likelier you would become the leader, "the big man." But such leadership could easily slip out of your hands. Power was something that all men held, and it was only through the consensus of the moment that one man held more of it than the others.

Thus, in pre-State societies, power is not a permanent structure that transcends the lifetime of any one leader. Power is the leader. It is highly personal and ephemeral, and these qualities extend to the tools of power, like speech. When describing Amerindian tribes in Paraguay, Pierre Clastres (1989 pp. 151-153) says:

To speak is above all to possess the power to speak. [...] the question to ask is not: who is your chief? but rather: who among you is the one who speaks? The master of words is what many groups call their chief.

[...] Indian societies do not recognize the chief's right to speak because he is the chief: they require that the man destined to be chief prove his command over words. Speech is an imperative obligation for the chief. The tribe demands to hear him: a silent chief is no longer chief.

This situation changes with the rise of the State, in particular with its monopoly on the use of violence. Social relations become more pacified, more structured, and less changeable, thus creating a culture of deference to authority. Speech is still manipulative but subtly so, as Rosen (1987) describes in Ethiopia:

For people who grow up speaking Amharic and Tigrinya, the idea of being precise with language is a foreign one. Ethiopians, perhaps Amharas more than Tigreans, are always on guard with others, suspicious about the motives of almost everyone, and on the alert for verbal assaults of one sort or another. The Amhara does not assume good intentions—he expects people to harbor disruptive inclinations. He deals with authority cautiously, always seeking to perfect his verbal means for giving vent to his criticisms and frustrations, but without incurring the wrath of powerful superiors.

[...] One must live a long time in the midst of Ethiopians, speaking with them in Amharic (or Tigrinya), in order to begin to appreciate how much calculation is invested in each phrase, each answer to a question, each overt response to a situation. That he who desires to do harm may always be polite, or that he who wishes to deliver an insult may include it in a finely-wrought compliment, is part of a general understanding of human nature. When a person speaks, he wants to do so subtly, being able to make his point effectively, yet not so directly that he might find himself involved in an altercation or worse with some equally sensitive opponent.

Social relations are still incompletely pacified in Ethiopia. This is partly because of recurring conflicts between central and peripheral sources of authority, but also because many people chose until recent times to be outlaws, i.e., those outside the sphere of State-imposed law:

In Ethiopia, an exceptionally fierce warrior could not always restrict himself to serving the common cause, or to being subservient to a particular chieftain. His alternative was to rebel, flee from the constraints of society and become a shifta. The dictionary defines this term to mean "outlaw, bandit, brigand, rebel". It was applied to anyone who committed a crime and then fled to the wilderness, thereafter living by stealth and cunning, if not, as was more than likely, by killing and highway robbery. As often as not, the shifta was also admired for being guabäz: for his courage and manliness, and, perhaps, most of all, for his daring in flouting the norms of the society. (Rosen, 1987)

Incomplete pacification also appears in the persistence of disruptive forms of speech, "when language is made into a weapon to attack or disrupt others":

One form of this is an Ethiopian penchant for backbiting, known in Amharic as chiqechiq. This appears when personal interests are asserted in the midst of group undertakings, often leading to the downfall of the community plan or project, and the disruption of joint undertakings. Another form is the studied use of hyperbole in order to magnify a case, or to gain attention for one's cause, even if this requires wild exaggeration of the truth. (Rosen, 1987)

Emergence of a free marketplace of ideas

I have argued elsewhere that the State's monopoly on violence created a new cultural environment that favored the survival of meeker and more submissive individuals (Frost, 2010). This environment also improved the prospects for individuals who used speech less aggressively. Because other individuals no longer posed a threat to life and property, and because trust had become the rule and not the exception, people were now freer to use speech simply for communication. It became possible to exchange ideas in good faith and judge them on their own merits. 

This development is analogous to the rise of the market economy. In a low-trust society, buyers and sellers can securely make their transactions only in small protected areas that are limited in space and time, i.e., shops and marketplaces. In a high-trust society, the market mechanism can spread beyond these isolated points of exchange to encompass the entire economy. Increased trust emancipated the marketplace of goods and services, and it had a similar effect on the marketplace of ideas.

Cultural or genetic evolution?

Selection acts on phenotypes, and only indirectly on genotypes. When speech began to be used in new ways, the old ways became a handicap for survival and reproduction. There was thus cultural selection for new speech patterns. But were these new patterns passed on only through learning? Or was there also selection for certain genetic predispositions?

There are predispositions that selection can act upon. Loudness of speech seems to have a heritable basis (Carmelli et al., 1988; Matthews et al., 1984). The same is true for deceitful behavior (Barker et al., 2009). Heritability is particularly high for Attention-Deficit/Hyperactivity Disorder (ADHD), which is characterized by certain speech differences:

Analysis of speech parameters during conversation, such as voice rhythm (rate and duration of pauses and vocalization, response latency), intensity, and frequency, has revealed marked differences in the timing and modulation of speech between children with ADHD and those with and without specific learning disabilities. They speak louder, fail to modulate their voice volume, speak for much longer at a stretch with many short pause durations during their talk, but take much longer to respond to the conversational partner. (Tannock, 2005)

This is not to say that ADHD became less prevalent with the pacification of social relations, but rather that this new cultural environment selected for certain heritable aspects of speech that are impaired by ADHD. Like many other genetic disorders, ADHD sheds light on the heritable variability that selection can act upon.  

In sum, when the State imposed a monopoly on the use of violence, it set in motion a process of gene-culture co-evolution with many consequences. Among other things, this process may have favored not only learned ways of speaking but also unlearned ways as well.

References 

Barker, E.D., H. Larson, E. Viding, B. Maughan, F. Rijsdijk, N. Fontaine, and R. Plomin. (2009). Common genetic but specific environmental influences for aggressive and deceitful behaviors in preadolescent males, Journal of Psychopathology and Behavioral Assessment, 31, 299-308.

http://www.drru-research.org/data/resources/55/Barker-E.-et-al.-2009.PDF

Carmelli, D., R. Rosenman, M. Chesney, R. Fabsitz, M. Lee, and N. Borhani. (1988). Genetic heritability and shared environmental influences of type A measures in the NHLBI Twin Study, American Journal of Epidemiology, 127 (5), 1041-1052. 

Clastres, P. (1989). Society against the State, New York: Zone Books.

Frost, P. (2010). The Roman State and genetic pacification, Evolutionary Psychology, 8(3), 376-389. http://www.epjournal.net/filestore/EP08376389.pdf

Matthews, K.A., R.H. Rosenman, T.M. Dembroski, E.L. Harris, and J.M. MacDougall. (1984). Familial resemblance in components of the type A behavior pattern: a reanalysis of the California type A twin study, Psychosomatic Medicine, November, 46, 512-22.

Rosen, C. (1987). Core symbols of Ethiopian identity and their role in understanding the Beta Israel today, in M. Ashkenazi and A. Weingrod (eds.) Ethiopian Jews and Israel, pp. 55-62, New Brunswick (U.S.A.): Transaction Books. 

Tannock, R. (2005). Language and mental health disorders: the case of HDHD, in W. Ostreng (ed.) Convergence. Interdisciplinary Communications 2004/2005, 45-53.

http://www.cas.uio.no/Publications/Seminar/Convergence_Tannock.pdf

Did Europeans become white in historic times?

 

Tătăroaice – Petre Iorgulescu-Yor (source). Today, the steppes north of the Black Sea lie within the European world—politically, culturally, and demographically. Not so long ago, they were home to nomads of Central Asian origin.

 

A new study shows that Europeans underwent strong selection for white skin, non-brown eyes, and non-black hair … during historic times!

Here we present direct estimates of selection acting on functional alleles in three key genes known to be involved in human pigmentation pathways—HERC2, SLC45A2, and TYR—using allele frequency estimates from Eneolithic, Bronze Age, and modern Eastern European samples and forward simulations. Neutrality was overwhelmingly rejected for all alleles studied, with point estimates of selection ranging from around 2-10% per generation. Our results provide direct evidence that strong selection favoring lighter skin, hair, and eye pigmentation has been operating in European populations over the last 5,000 y. (Wilde et al., 2014) 

 

If true, this finding would contradict other recent findings. Two studies have found a much earlier time frame for the whitening of European skin: 11,000 to 19,000 years ago (Beleza et al., 2013) and 7,600 to 19,200 years ago (Canfield et al., 2014). Two studies of ancient DNA indicate that non-brown eyes were already in existence 7,000 years ago in Spain (Olalde et al., 2014) and 8,000 years ago in Luxembourg (Lazaridis et al., 2013). Moreover, the genes responsible are the same as the ones in above quote. 

So who is right and who is wrong? All of these studies are probably right, but only for some early Europeans and not for all. In the latest study, the samples come from a very small part of Europe—the steppes north of the Black Sea:²

Ancient DNA was retrieved from 63 out of 150 Eneolithic (ca. 6,500-5,000 y ago) and Bronze Age (ca. 5,000-4,000 y ago) samples from the Pontic-Caspian steppe, mainly from modern-day Ukraine. […] We also genotyped the three pigmentation-associated SNPs in a sample of 60 modern Ukrainians (28) and observed an increase in frequency of all derived alleles between the ancient and modern samples from the same geographic region (Table 1 and Fig. S1). This implies that the pigmentation of the prehistoric population is likely to have differed from that of modern humans living in the same area.

[…] Inferring natural selection based on temporal differences in allele frequency requires the assumption of population continuity. To this end we compared the 60 mtDNA HVR1 sequences obtained from our ancient sample to 246 homologous modern sequences (29–31) from the same geographic region and found low genetic differentiation (F_ST = 0.00551; P = 0.0663) (32). Coalescent simulations based on the mtDNA data, accommodating uncertainty in the ancient sample age, failed to reject population continuity under a wide range of assumed ancestral population size combinations. (Wilde et al., 2014)

The authors are placing the burden of proof on the wrong null hypothesis when they state that their simulations “failed to reject population continuity.” The null hypothesis should be population discontinuity. For example, Swedes and Greeks differ in skin tone and eye color, and if we compare their autosomal DNA we get a comparable F_ST of 0.0084 (Genetic History of Europe, 2014). Admittedly, F_ST is different with mitochondrial DNA.

I suspect the authors ruled out population discontinuity because their F_ST seemed incompatible with a non-European population giving way to a European one. If so, they forgot one thing. They were comparing a population of the present with one that existed some 5,000 years ago. If you go farther and farther back in time, any human population will look more and more ancestral to a present-day population. This is especially so in northern Eurasia, where a population ancestral to both Europeans and Amerindians existed some 20,000 years ago. Yes, the F_ST does seem incompatible with a non-European population giving way to a European one, but this is because the ancient DNA comes from a non-European population that was closer to the time of common origin for all northern Eurasians.

This ancient DNA may come from a mixed European/Central Asian population or an intermediate and now extinct population, perhaps similar to the Lapps. If we look at the derived (European) alleles for the three genes in question (HERC2, SLC45A2, TYR), the frequencies fall halfway between those of Europeans and Asians (see Table 1 in the paper). In any case, this population does not have to be of non-European origin to be noticeably darker in skin color. As shown by the recent Mesolithic findings from Luxembourg and Spain, there used to be apparently native dark-skinned populations in the heart of Europe.

 

Historical background 

The hypothesis of population discontinuity becomes even more plausible if we look at the history of this region. Today, the steppes north of the Black Sea lie within the European world—politically, culturally, and demographically. Not so long ago, they were home to nomads of Central Asian origin. The latest of them, the Tatars, held sway until the 18th century.

The Tatars intermixed extensively with Slavic wives and concubines, so much so that they now look almost as fair as other Europeans. But they were originally quite swarthy, as attested by medieval sources. In a 14th-century romance, The King of Tars, a Tatar Khan converts to Christianity and turns white in the baptismal water. Two other chronicles of the same period describe how a Tatar Khan's Christian concubine bears him a son white on one side and black on the other. When baptized, the child emerges from the water white on both sides (Hornstein, 1941; Metlitzki, 1977, p. 137).

Medieval writers often noticed this difference in skin color. Genoese notaries usually described Tatar slaves as olive-skinned (Plazolles Guillen, 2012, p. 119). Florentine acts of sale give the following numerical breakdown of Tatar slaves by skin color: black 2, brown 18, olive 161, fair 11, reddish 5, white 45 (Epstein, 2001, p. 108). During a trial, a slave tried to regain her freedom by claiming to be Russian and, hence, Christian. Her owner rebuked her, saying: “You’ve lied to me. You look more like a Tatar, not at all like a Russian” (Plazolles Guillen, 2012, p. 119).

The Tatars were preceded by other nomads of Central Asian origin. The Scythians (8th to 2nd century BC) were likewise described as dark-skinned. Hippocrates wrote: “The Scythian race are tawny from the cold, and not from the intense heat of the sun, for the whiteness of the skin is parched by the cold, and becomes tawny” (Hippocrates).

One can find references to the contrary (Scythians, 2014). Keep in mind that the word “Scythian” was often used in the ancient world to encompass all northern peoples:

To the ancient Greeks the Scythians, Sarmatians, Germans, and Goths were the remote northern races of antiquity. Geographically near to one another, they were often grouped together under the term “Scythians,” which by the third century B.C.E. no longer had an ethnic or national connotation and had come to designate the peoples of the remote north. (Goldenberg, 2003, p. 43)

The term “Scythian” may also have subsumed different peoples north of the Black Sea, some of whom came from Central Asia and others from areas farther north and west.

 

Conclusion

Because this region is on the periphery of the European world and has been exposed to migrations from Central Asia, population change is a likelier explanation for the findings of Wilde et al.

These findings are nonetheless interesting. Together with the ancient DNA from Mesolithic hunter-gathers in Spain and Luxembourg, we have further proof that many early Europeans were brown-skinned. Indeed, this seems to have been the physical appearance of all Europeans during their first 20,000 years in Europe. Only later, within the time frame of 20,000 to 10,000 years ago, did some of them become white.

This may seem surprising to those who believe that white skin is an adaptation to weak sunlight at high latitudes. It was thought that Europeans became white because their ancestors no longer needed dark pigmentation to protect themselves against sunburn and skin cancer. Meanwhile, light pigmentation became necessary to maintain synthesis of vitamin D. There was admittedly the example of dark-skinned peoples who have long lived at similar latitudes in Asia and North America, but that counterfactual was attributed to the availability of vitamin D from a marine diet, such as among the Inuit of northern Canada.
 

Wilkes et al. do, in fact, address the apparent contradiction between their findings and the hypothesis that ancestral Europeans became white to maintain adequate production of vitamin D in their skin. In their Discussion section, they suggest that the shift from hunting and gathering to farming led to a decrease in dietary vitamin D (from fatty fish and animal liver). The main problem with this explanation is that farming came late to many parts of Europe: about 2,000 to 3,000 years ago for East Baltic peoples and less than 3,000 years ago for Finnish peoples (and incompletely at that). This leaves a very narrow time frame for evolution from brown skin to white skin. Ultimately, this question will be resolved with retrieval of ancient DNA from these populations.

 

Notes

1. Although Wilde et al. mention hair color, they did not study the main hair-color gene, MC1R.

2. Razib Khan has a great map of the ancient DNA samples.

 

References 

Beleza, S., Murias dos Santos, A., McEvoy, B., Alves, I., Martinho, C., Cameron, E., Shriver, M.D., Parra E.J., and Rocha, J. (2013). The timing of pigmentation lightening in Europeans. Molecular Biology and Evolution, 30, 24-35.

http://mbe.oxfordjournals.org/content/30/1/24.short 

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

http://www.g3journal.org/content/3/11/2059.full 

Epstein, S.A. (2001). Speaking of Slavery. Color, Ethnicity, & Human Bondage in Italy, Ithaca: Cornell University Press. 

Genetic History of Europe. (2014). Wikipedia

http://en.wikipedia.org/wiki/Genetic_history_of_Europe

Goldenberg, D.M. (2003). The Curse of Ham. Race and Slavery in early Judaism, Christianity, and Islam, Princeton: Princeton University Press. 

Hippocates. On Airs, Waters, and Places, part 20. Translated by Francis Adams

http://classics.mit.edu/Hippocrates/airwatpl.20.20.html

Hornstein, L.H.  (1941). New analogues to the King of Tars, Modern Language Review, 36, 433-442. 

Khan, R. (2014). Descent and selection is a bugger: Black Kurgans, March 12, The Unz Review: An Alternative Media Selection

http://www.unz.com/gnxp/descent-and-selection-is-a-bugger/ 

Lazaridis, I., Patterson, N., Mittnik, A., Renaud, G., Mallick, S., et al. (2013). Ancient human genomes suggest three ancestral populations for present-day Europeans, BioRxiv, December 23.

http://biorxiv.org/content/early/2013/12/23/001552.full-text.pdf+html

Metlitzki, D. (1977). The Matter of Araby in Medieval England, New Haven and London, Yale University Press. 

Olalde, I., M.E. Allentoft, F. Sanchez-Quinto, G. Saintpere, C.W.K. Chiang, et al. (2014).  Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European, Nature, early view

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12960.html

Plazolles Guillen, F. (2012). “Negre e de terra de negres infels …”: Servitude de la couleur (Valence, 1479-1516), in R. Botte and A. Stella (eds.) Couleurs de l’esclavage sur les deux rives de la Méditerranée (Moyen Âge – xx^e siècle), pp. 113-158, Paris: Karthala. 

Scythians. (2014). Wikipedia

http://en.wikipedia.org/wiki/Scythians  

Wilde, S., A. Timpson, K. Kirsanow, E. Kaiser, M. Kayser, M. Unterländer, N. Hollfelder, I.D. Potekhina, W. Schier, M.G. Thomas, and J. Burger. (2014). Direct evidence for positive selection of skin, hair, and eye pigmentation in Europeans during the last 5,000 y, Proceedings of the National Academy of Sciences, published ahead of print.

http://www.pnas.org/content/early/2014/03/05/1316513111.full.pdf+html

Population differences in intellectual capacity: a new polygenic analysis

 

PISA test documents at a German school (source: Theo Müller). PISA and IQ tests are informing us about differences in intellectual capacity by country. Meanwhile, genetic studies are informing us about genomic differences by country. Davide Piffer has been tapping into these two pools of data to explore the links between genes and intellectual capacity.

 

Between individuals and populations, intellectual capacity seems to differ through small differences at many genes. This is hardly surprising. Intelligence is a complex trait that involves many different genes interacting with each other and with the environment. If one gene changes, the immediate effect may be beneficial, but there will be side effects at other genes, and most of those side effects will likely be harmful. The bigger the effect at any one gene, the greater the likelihood of negative side effects elsewhere.

So evolution has proceeded through tinkering. A small effect here, a small effect there, but nothing that will rock the boat.

We must therefore pool data from many genes to understand the evolution of complex traits like intelligence. This is what Davide Piffer (2013) has done in a recent study. He began with seven genes (SNPs) whose different alleles are associated with differences in intellectual capacity, as measured by PISA or IQ tests. Then, for fifty human populations, he looked up the prevalences of the alleles that seem to increase intellectual capacity. Finally, for each population, he calculated their average prevalence at all seven genes.

The average prevalence was 39% among East Asians, 36% among Europeans, 32% among Amerindians, 24% among Melanesians and Papuan-New Guineans, and 16% among sub-Saharan Africans. The lowest scores were among San Bushmen (6%) and Mbuti Pygmies (5%). A related finding is that all but one of the alleles seem to be derived. In other words, they are specific to humans and not shared with ancestral primates.

Since these alleles have only small effects on intellectual capacity, there might be other causes for the above geographic pattern. For instance, as modern humans spread out of Africa, older alleles would have gradually given way to newer ones simply through founder effects and other random events. On the other hand, these derived alleles do not reach their highest prevalence in populations that are farthest removed from Africa, like the native inhabitants of the Americas and Oceania. The highest prevalences are actually reached less far away, in Europe and East Asia. Furthermore, the African/non-African difference is much greater for these alleles than for derived alleles in general. Derived alleles typically have a prevalence of 42% among sub-Saharan Africans and 56-57% among East Asians and Europeans (Watkins et al., 2001). This difference is tiny in comparison to the one for alleles that seem to increase intellectual capacity.

 

Principal component analysis

In this study and in a subsequent one (Piffer, 2014), principal component analysis has shown that a single factor explains much of the variability in the data (45%). Moreover, this one factor correlates highly with average IQ scores (r=0.9) and PISA scores (r=0.8) for each population. A common neural property thus seems to be the target of the various derived alleles. Could it be the elusive g factor?

The existence of such a large factor is further proof that we are dealing with some kind of selection pressure, and not random genetic changes like founder effects. It doesn’t follow, however, that the “unexplained variability” is without significance. Selection for intellectual capacity, like selection for any complex trait, may follow different paths in different cultural contexts. Moreover, there may be tradeoffs between different kinds of mental ability, and these tradeoffs may likewise vary according to the cultural context.

 

A final caveat

These seven genes are a small subset of the many genes that affect intellectual capacity. They thus provide only a rough picture of how this trait varies within the human species. Nonetheless, this picture is probably not far from reality. 

 

References

 

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, Interdisciplinary Bio Central, provisional manuscript

http://www.ibc7.org/article/journal_v.php?sid=312 

Piffer, D. (2014). Simple statistical tools to detect signals of recent polygenic selection, Interdisciplinary Bio Central, 6, article 1

http://www.ibc7.org/article/journal_v.php?sid=317

Watkins, W.S., C.E. Ricker, M.J. Bamshad, M.L. Carroll, S.V. Nguyen, M. A. Batzer, H.C. Harpending, A.R. Rogers, and L.B. Jorde. (2001). Patterns of ancestral human diversity: An analysis of Alu-insertion and restriction-site polymorphisms, American Journal of Human Genetics, 68, 738-752.

The paradox of the Visual Word Form Area

 

Luke the Evangelist (source: British Library). In the past, only a minority could read long texts of cursive writing. But many more could read short texts of block writing.

 

The Visual Word Form Area (VWFA) is a specialized part of the brain that helps us recognize written words and letters. If it is subjected to a surgical lesion, the patient will suffer a clear impairment to reading ability but not to recognition of objects, names, or faces or to general language abilities. There will be some improvement over the next six months, but reading will still take twice as long as it had before surgery (Gaillard et al, 2006).

Most of the initial skepticism over the existence of the VWFA has disappeared. There does seem to be, however, much variability in its size. An area that may fall within this mental organ in one person may fall outside it in someone else (Glezer and Riesenhuber, 2013).

In addition to word recognition, the VWFA may participate in higher-level processing of word meaning:

[It seems that] the VWFA would not only be recruited at an early stage for allowing low-level (script processing) word processing as has been previously instantiated (Pammer et al., 2004; Dehaene and Cohen, 2011), but also at a later stage for gating high-level (lexico-semantic) processing. Such late semantic gateway would not be selective to the VWFA but rather emerge in the posterior LOT and extend anteriorly to the VWFA. (Levy et al., 2013)

The VWFA is described in the above study as a “bottleneck to consciousness.” It helps us not only to recognize words on a page but also to understand what the words mean. To me, this makes sense. I’m better at thinking through an idea and its implications if I can write it down and then read it. There thus seems to be a single mental pathway that does double duty: processing character strings (words) and processing higher-level concepts.

 

Population differences 

The VWFA functions differently in different human populations. The difference is striking between people who use alphabetical script, where each symbol represents a sound, and those who use logographic script, where each symbol represents an idea. Chinese subjects process their idea-based symbols with assistance from other brain regions, whereas Westerners process their sound-based symbols only in the VWFA (Liu et al., 2008). Similarly, dyslexics activate this brain region in ways that differ by linguistic background, apparently because of differences in spelling and writing (Paulesu et al., 2001).

Hardwired or softwired?

For Dehaene and Cohen (2011), the VWFA is not a hardwired mental organ. They argue that it occupies the same area of the brain because that is where we can most easily recruit neurons when learning to recognize words. But why, then, does this recruitment happen so fast in young children? When kindergarten children were asked to play a grapheme/phoneme correspondence game, their VWFAs preferentially responded to pictures of letter strings after a total of 3.6 hours over an 8-week period. It is worth noting that only a few of these children could actually read, and even then only at a rudimentary level (Brem et al., 2010; Dehaene et al., 2010).

But the alternative view, hardwiring, is also hard to accept. Reading began not in the Paleolithic but in historic times, less than 6,000 years ago. Widespread literacy is even more recent, and there are still many societies where most people cannot read or write. How could an entirely new mental organ have evolved over so short a time?

Yet this alternative view may not be so farfetched. Let’s examine the two main objections.

Was there not enough time for natural selection to work?

The VWFA did not evolve out of nothing. It seems to be a population of neurons that originally served to recognize faces (Dehaene and Cohen, 2011). This sort of recycling is a common pathway for natural selection and explains much of the apparent rapidity of evolution. A complex mental adaptation may take a long time to evolve, but much less time is needed to develop an exaggerated version of it or to alter when and how it becomes activated (Harpending and Cochran, 2002).

Indeed, parallel to the way alphabetical reading ability has spread historically and geographically, there is a similar spread of the latest variant of ASPM, a gene implicated in the regulation of brain growth. In humans, a new variant arose about 6,000 years ago in the Middle East. It eventually became more prevalent in the Middle East (37-52% incidence) and Europe (38-50%) than in East Asia (0-25%) (Frost, 2011; Mekel-Bobrov et al., 2005). 

Would it have benefited too few people to have been favored by natural selection?

There is some debate over the relative recentness of literacy. It is true that before the modern era only a small minority could read long texts of cursive writing. But the ability to read short texts of block writing was much more widespread, as evidenced by the prevalence of graffiti and storefront signs. We should also keep in mind that the literate few contributed disproportionately to the gene pool of subsequent generations. Clark (2007) has shown that the English lower class is largely descended from people who were middle or upper class a few centuries ago. In the ancient world, there was a perception that scribes enjoyed reproductive success. The Book of Sirach [39: 11] states: “If [a scribe] lives long, he will leave a name greater than a thousand.” 

Gene-culture co-evolution?

There may have been positive feedback between reading ability and the cultural opportunities it created. One example is the scientific revolution in Western Europe (15th - 18th centuries), which took off once a critical mass of scholars could read each other’s papers. In short, reading and writing are advantageous to the extent that other people can read and write. While this kind of feedback loop is self-evident, its biological implications may be less so. The same feedback loop would have steadily ratcheted up selection for the VWFA and, subsequently, for higher-level faculties. This might explain why the VWFA evolved beyond word recognition per se and towards lexico-semantic tasks.

Future research

One priority would be to study the VWFA in populations that have become literate only in recent times. What form, if any, does it take in such people? A study in New York elementary schools found that VWFA activation varied with socioeconomic status. In students from high SES families, activation seemed to be more hardwired and less dependent on familiarity with the way sounds are visually represented. Unfortunately, there was no attempt to break the data down by ethnic background (Noble et al., 2006).

At present, high VWFA activation is attributed to an environment where reading material is accessible and parents very supportive, this being in turn attributed to high SES. Yet reading material is ubiquitous nowadays. And how crucial is parental support? As a child, I read almost always on my own with little encouragement at home or school. My teachers were in fact annoyed by my habit of sneaking into the small storage room where old textbooks and encyclopedias were kept (we had no library). “If you’ve finished your assignment, stay at your desk. Is that clear?!”

Nonetheless, I read voraciously, even when I couldn’t understand half of what I read. Strange new words were a source of pleasure, and I would often read and reread the same texts simply because I liked the flow of the words and the images they conjured up.

 

References 

Brem, S., S. Bach, K. Kucian, T.K. Guttorm, E. Martin, H. Lyytinen, D. Brandeis, and U. Richardson. (2010). Brain sensitivity to print emerges when children learn letter-speech sound correspondences, Proceedings of the National Academy of Sciences U.S.A., 107, 7939–7944.

http://psyserv06.psy.sbg.ac.at:5916/fetch/PDF/20395549.pdf

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

Dehaene, S. and L. Cohen. (2011). The unique role of the visual word form area in reading, Trends in Cognitive Sciences, 15, 254-262.

http://www.cnbc.pitt.edu/~plaut/VisCog/papers/DehaeneCohen11TICS.VWFA.pdf  

Dehaene, S. et al. (2010). How learning to read changes the cortical networks for vision and language, Science, 330, 1359–1364.

http://gondabrain.ls.biu.ac.il/Neuroling/courses/877/Dehaene_Science2010.pdf

Frost, P. (2011). Human nature or human natures? Futures, 43, 740-748.

http://dx.doi.org/10.1016/j.futures.2011.05.017  

Gaillard, R., Naccache, L., P. Pinel, S. Clémenceau, E. Volle, D. Hasboun, S. Dupont, M. Baulac, S. Dehaene, C. Adam, and L. Cohen. (2006). Direct intracranial, fMRI, and lesion evidence for the causal role of left inferotemporal cortex in reading, Neuron, 50, 191-204.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.76.7620&rep=rep1&type=pdf

 

Glezer, L.S. and M. Riesenhuber. (2013). Individual variability in location impacts orthographic selectivity in the “Visual Word Form Area”, The Journal of Neuroscience, 33(27), 11221–11226.

http://www.jneurosci.org/content/33/27/11221.full  

Harpending, H., and G. Cochran. (2002). In our genes, Proceedings of the National Academy of Sciences USA, 99(1), 10-12.

http://www.wcas.northwestern.edu/nescan/2008-2009%20papers/harpending%20-%20in%20our%20genes.pdf  

Levy, J., J.R Vidal, R. Oostenveld, I. FitzPatrick, J-F. Démonet, and P. Fries. (2013). Alpha-band suppression in the Visual Word Form Area as a functional bottleneck to consciousness, NeuroImage,78C, 33-45.

http://hal.inria.fr/docs/00/81/96/67/PDF/Levy_et_al.pdf  

Liu, C., W-T. Zhang, Y-Y Tang, X-Q. Mai, H-C. Chen, T. Tardif, and Y-J. Luo. (2008). The visual word form area: evidence from an fMRI study of implicit processing of Chinese characters, NeuroImage, 40, 1350-1361.

http://psychbrain.bnu.edu.cn/teachcms/res_base/teachcms/upload/channel/file/2010_4/11_25/6hlcggx7rk3z.pdf  
Mekel-Bobrov, N., S.L. Gilbert, P.D. Evans, E.J. Vallender, J.R. Anderson, R.R. Hudson, S.A. Tishkoff, and B.T. Lahn. (2005). Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens, Science, 309, 1720-1722.
http://ftp.eebweb.arizona.edu/faculty/nachman/Archived%20Research%20Papers/mekel_bobrov_et_al_2005.pdf  

Noble, K.G., M.E. Wolmetz, L.G. Ochs, M.J. Farah, and B.D. McCandliss. (2006). Brain–behavior relationships in reading acquisition are modulated by socioeconomic factors, Developmental Science, 9, 642–654.

http://www.cumc.columbia.edu/dept/sergievsky/fs/publications/Noble-et-al-2006-2.pdf  

Paulesu E., J.F. Démonet, F. Fazio, E. McCrory, V. Chanoine, N. Brunswick et al (2001). Dyslexia: cultural diversity and biological unity, Science, 291, 2165–2167.

http://www.drru-research.org/data/resources/42/Paulesu-et-al-2001.pdf