Saturday, August 23, 2014

How modular is intelligence?

Great at reading or recognizing faces? You might not do so well on an IQ test. Source: Histoire naturelle générale et particulière avec la Description du Cabinet du Roy (1749) (Wikicommons)


The English psychologist Charles Spearman was the first to argue that a single factor, called "g," explains most of the variability in human intelligence. When observing the performance of children at school, he noticed that a child who did well in math would also do well in geography or Latin. There seemed to be a general factor that facilitates almost any kind of mental task.

Spearman did, however, acknowledge the existence of other factors that seem more task-specific:

[...] all branches of intellectual activity have in common one fundamental function (or group of functions), whereas the remaining or specific elements of the activity seem in every case to be wholly different from that in all the others. (Spearman, 1904, p. 284) 

That is where things stood for over a century. In recent years, however, we’ve begun to identify the actual genes that contribute to intelligence. These genes are very numerous, numbering perhaps in the thousands, with each one exerting only a small effect. Many act broadly on intelligence in general and may correspond to the g factor, which seems to be a widespread property of neural tissue, perhaps cortical thickness or the integrity of white matter in the brain. Other genes act more narrowly on specific mental tasks. The ability to recognize faces, for instance, seems to have no relation at all to general intelligence. You can be great at recognizing faces while being as dumb as rocks (Zhu et al., 2009).

One way to locate these genes is through genome-wide association studies. We look at the various alleles of genes whose locations are already known, typically SNPs (single nucleotide polymorphisms), and see whether this source of variability correlates with variability in a mental trait. If we find a significant correlation, the genes for that trait must be nearby. The same kind of study can also show us how narrowly or broadly these genes act. Do they merely influence intelligence in general? Or do they provide more specific instructions? Such as how to recognize certain objects or how to react to them?

A genome-wide association study has recently shed light on various mental traits. In most cases, a common factor seems to explain about half of the genetic variability. This common factor is weakest for emotion identification, i.e., the ability to identify the emotions of other people by their facial expressions. Emotion identification actually correlates negatively with nonverbal reasoning (-0.25) and only weakly with verbal memory (0.17) and spatial reasoning (0.26). The highest correlation is with reading (0.40) and language reasoning. (0.45). Reading and language reasoning are highly intercorrelated, perhaps because they share the same mental module (Robinson et al., 2014).

This partial modularity has been confirmed by a recent twin study on reading and math ability. If we look at the genetic component of either reading or math ability, at least 10% and probably half affects performance on both tasks. Conversely, the other half is specific to either one or the other (Davis et al., 2014).

An evolutionary mystery?

But how can reading ability have a specific genetic basis if people began to read only in historic times? Indeed, history is said to begin with the first written documents. Surely humans weren't still evolving at that point?

To ask the question is to answer it. Not only were they still evolving, they were actually doing so at a faster pace than their prehistoric ancestors. Humans have undergone much more genetic change over the past 10,000 years than over the previous 100,000 (Hawks et al., 2007). This is a difficult fact to swallow, let alone digest, but we must learn to accept it and all of its implications.

The new findings on reading ability are consistent with other ones. The human brain has a special region, called the Visual Word Form Area, that is used to recognize written words and letters. If it is damaged, your reading ability will suffer but not your recognition of objects, names, faces, or general language abilities. There will be some improvement over the next six months, but reading will still take twice as long as it had previously. This brain region varies in size and organization from one individual to another and from one human population to another, being differently organized in Chinese people than in Europeans (Frost, 2014; Gaillard et al, 2006; Glezer and Riesenhuber, 2013; Levy et al., 2013; Liu et al., 2008).

Genome-wide association studies may help us pinpoint the actual genes responsible for the Visual Word Form Area. In fact, we may have already found one: ASPM. This gene influences brain growth in other primates and has evolved in humans right up into historic times. Its latest allele arose about 6000 years ago in the Middle East and proliferated until it reached incidences of 37-52% in Middle Easterners, 38-50% in Europeans, and 0-25% in East Asians. Despite its apparent selective advantage, this allele does not improve performance on IQ tests (Mekel-Bobrov et al.,2007; Rushton et al., 2007). It is nonetheless associated with larger brain size in humans (Montgomery and Mundy, 2010).

Its Middle Eastern origin some 6000 years ago suggests this allele may have owed its success to the invention of writing. Most people had trouble reading, writing, and copying lengthy texts in ancient times, when characters were written continuously with little or no punctuation. There was an acute need for scribes who could excel at this task, and such people were rewarded with reproductive success (Frost, 2008; Frost, 2011).


Human intelligence is modular to varying degrees, and much of this modularity seems to have arisen during historic times. It is a product of humans adapting not only to their physical environments but also to their more rapidly evolving cultural environments.

While there is such a thing as general intelligence, it seems to be only half of the picture. Two people may have the same IQ and yet differ significantly in various mental abilities. There may also be trade-offs between general intelligence and more specific mental tasks. If you're great at abstract reasoning, you may be lousy at decoding facial expressions. This may be because the two abilities compete with each other for limited mental resources. Or it may be that selection for abstract reasoning has occurred in an environment where people can trust each other and have no need to scrutinize facial expressions for signs of lying ... or imminent physical assault. 

The same applies to human populations. Two populations may have the same mean IQ, and yet differ statistically over a large number of mental and behavioral traits. Although these differences may be scarcely noticeable if we compare two individuals taken at random from each population, their accumulative effect over many thousands of individuals can steer one population along one path of cultural evolution and the other along another. Furthermore, two populations may arrive at a similar outcome via different paths of cultural evolution and via different mental and behavioral packages. Europeans and East Asians have both reached an advanced level of societal development, but this similar outcome has been achieved in East Asian societies largely through external mediation of rule enforcement (e.g., shaming, peer pressure, family discipline) and in European ones mainly through internal means of control (e.g., guilt, empathy).


Davis, O.S.P., G. Band, M. Pirinen, C.M.A. Haworth, E.L. Meaburn, Y. Kovas, N. Harlaar, et al. (2014). The correlation between reading and mathematics ability at age twelve has a substantial genetic component, Nature Communications, 5 

Frost, P. (2008). The spread of alphabetical writing may have favored the latest variant of the ASPM gene, Medical Hypotheses, 70, 17-20.

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

Frost, P. (2014). The paradox of the Visual Word Form Area, March 1, Evo and Proud 

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.  

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. 

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

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. 

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.  

Mekel-Bobrov, N., Posthuma, D., Gilbert, S. L., Lind, P., Gosso, M. F., Luciano, M., et al. (2007). The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence, Human Molecular Genetics, 16, 600-608.  

Montgomery, S. H., and N.I. Mundy. (2010). Brain evolution: Microcephaly genes weigh in, Current Biology, 20, R244-R246.  

Robinson, E.B., A. Kirby, K. Ruparel, J. Yang, L. McGrath, V. Anttila, B.M. Neale, K. Merikangas, T. Lehner, P.M.A. Sleiman, M.J. Daly, R. Gur, R. Gur and H. Hakonarson. (2014). The genetic architecture of pediatric cognitive abilities in the Philadelphia Neurodevelopmental Cohort, Molecular Psychiatry, published online July 15

Rushton, J. P., Vernon, P. A., and Bons, T. A. (2007). No evidence that polymorphisms of brain regulator genes Microcephalin and ASPM are associated with general mental ability, head circumference or altruism, Biology Letters, 3, 157-160.

Spearman, C. (1904). "General intelligence," objectively determined and measured, The American Journal of Psychology, 15, 201-292.

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

Saturday, August 16, 2014

Getting the babes but not the babies


Still from the film Is Matrimony a Failure? (1922). Who's making more babies? "Good boys" or "bad boys"? Originally, the good boys were, thanks to parental monitoring of relations between single men and single women. The pendulum then swung toward the bad boys in the 1940s, only to swing back after the 1960s.


A recent Swedish study has found that "bad boys" are outbreeding "good boys":

Convicted criminal offenders had more children than individuals never convicted of a criminal offense. Criminal offenders also had more reproductive partners, were less often married, more likely to get remarried if ever married, and had more often contracted a sexually transmitted disease than non-offenders. Importantly, the increased reproductive success of criminals was explained by a fertility increase from having children with several different partners. (Yao et al., 2014)

This study has been much talked about, yet few people have noticed its one big flaw. Sweden has many citizens of foreign origin whose crime and fertility rates exceed those of the native population (Crime in Sweden, 2014; Landes, 2008). Reproductive success may thus correlate with criminality simply because both tend to be higher among non-natives than among natives. Admittedly, this alternate explanation had been foreseen by the authors of the study and they tried to correct for it:

We included variables potentially associated with both criminal and reproductive behavior as covariates. [...] Immigrant status has been associated with both rule breaking, primarily through associations with other familial and socioeconomic risk markers (Moehling & Piehl, 2009), and adherence to cultural norms influencing fertility and monogamy-related outcomes (Coleman, 2006). The migration register provided information on immigrant status defined as being born in Sweden or not. (Yao et al., 2014)

Unfortunately, country of birth is no longer a satisfactory proxy for cultural identity, at least not in Sweden's case. There is now a large Swedish-born population that self-identifies as Pakistani, Somali, or Afghan, including the youths who rioted in Malmö last year. The Swedish crime rate is influenced almost as much by the Swedish-born of foreign background as by the foreign-born:

During the period 1997-2001, 25% of the almost 1,520,000 offences for which a perpetrator was convicted were committed by people born in the Middle East or Eastern Europe, while almost 20% were committed by people with a foreign background who were born in Sweden. (Crime in Sweden, 2014)

If we could examine only people of Swedish descent, I doubt reproductive success would still correlate with criminality or, more exactly, with a tendency to "love and leave" one woman after another. Such a correlation used to exist in the U.S. but disappeared almost half a century ago. This was the conclusion of Jason Malloy and JayMan (2012) when they used General Social Survey data to find out the number of children fathered by monogamous men ("good boys") versus men who had several female sex partners ("bad boys"). It seems that the reproductive success of bad boys has varied a lot over time:

Men born before 1920 - courtship under parental supervision 

In this cohort, good boys were the top breeders. No need to think hard to find the reason. Any man wishing to meet a single woman, other than a prostitute, had to run a gauntlet of parental supervision. The preferred form of courtship was still "calling." If a woman struck your fancy, you could "call" on her at her home. If she and her parents were favorably impressed, you could come back for further visits and eventually start taking her out to social events. Otherwise, that would be the end of it. A more direct approach could get you in big trouble, as a reference book for American lawmakers explained in 1886:

The state should punish, not only treacherous inducements to incontinence or to unchastity when accompanied by the violation of particular duties, and the seduction of minors, or girls under sixteen, but also seduction when it assumes a character dangerous to the interests of the community. It is not the duty of the state to make the individual moral, or to protect her against temptations to immorality; but it should endeavor to prevent all acts of immorality calculated to poison family life and the life of the nation. (Lalor, 1886, vol.III, p. 211)

The concern here is not just venereal disease, but also a family's genetic heritage. In the 19th century, people believed that a part of their essence was reincarnated in their children and grandchildren. Their concern over sex was fueled not by irrational hang-ups but by a very rational desire to maintain the integrity of their family line. Bad boys threatened that integrity, and it was not for nothing that many ended up in jail ... or at the end of a rope.

Men born between 1920 and 1939 - rise of dating, illegitimacy, and adoption

In this cohort, bad boys were the top breeders. Parental supervision had slackened with the replacement of calling by dating, thus creating new opportunities for them to sow their seed. A sharp rise in illegitimacy led to a sharp rise in adoption:

[...] The period 1945 to 1974, the baby scoop era, saw rapid growth and acceptance of adoption as a means to build a family. Illegitimate births rose three-fold after World War II, as sexual mores changed. Simultaneously, the scientific community began to stress the dominance of nurture over genetics, chipping away at eugenic stigmas. In this environment, adoption became the obvious solution for both unwed mothers and infertile couples. (Adoption, 2014)

Adoption had previously been very rare. As late as 1923, only 2% of children without parental care ended up in adoptive homes, the others going to foster homes or orphanages (Adoption, 2014). And a large chunk of that 2% involved adoptions between related families. These statistics are mirrored by my family tree: whenever children were left with no provider, they would be adopted by an aunt or an uncle or placed in a foster home. In those days, changing your family identity was as unthinkable as changing your religion or nationality.

To deal with the surge of illegitimacy, progressive-minded people now turned toward a seemingly great idea. On the one hand, there were babies abandoned by deadbeat dads. On the other, there were middle-class families with loving homes. Why not transfer these babies from the dads who don't love them to the ones who can?

The 20th century is littered with great ideas that proved to be not so great. Adoption is no exception. One negative outcome, which could have been foreseen, is that adopted children tend to replicate the psychological profile of their biological fathers. In one study, Gibson (2009) notes:

Adoptees were more likely than genetic offspring to have ever received public assistance, been divorced or been arrested. They also completed fewer years of schooling and were more likely to have ever required professional treatment for mental health, alcohol and drug issues.

[...] This supports other research showing that, compared to genetic children, American adoptees have a higher overall risk of contact with mental health professionals, specifically for eating disorders, learning disabilities, personality disorders and attention deficit hyperactivity disorder [...] They also have lower achievement and more problems in school, abuse drugs and alcohol more, and fight with or lie to parents more than genetic children [...]

These problems are not due to adoptive parents shortchanging adoptees. In fact, the reverse seems true:

This study categorically fails to support the hypothesis that parents bias investment toward genetically related children. Every case of significant differential investment was biased toward adoptees. Parents were more likely to provide preschool, private tutoring, summer school, cars, rent, personal loans and time with sports to adopted children. (Gibson, 2009)

Adoption does seem to improve the behavior of these children. It lowers their risk of committing violent crime, although they remain just as likely to commit other offences:

The possibility that genetic factors are among the causes of criminal behavior was tested by comparing court convictions of 14,427 adoptees with those of their biological and adoptive parents. A statistically significant correlation was found between the adoptees and their biological parents for convictions of property crimes. This was not true with respect to violent crimes. There was no statistically significant correlation between adoptee and adoptive parent court convictions. Siblings adopted separately into different homes tended to be concordant for convictions, especially if the shared biological father also had a record of criminal behavior. (Mednick et al., 1984)

With respect to intellectual capacity, adoptees likewise seem to benefit from their new homes, although the benefit tends to wash out over time. When children with two white biological parents were adopted into white middle-class homes, they initially did somewhat better than their non-adopted siblings, as seen on IQ tests at the age of 7. By the age of 17, however, the situation had reversed, with the adoptees falling behind their non-adopted siblings in terms of IQ, GPA, class ranking, and school aptitude (Minnesota Transracial Adoption Study, 2014).

Clearly, adoptees are getting some benefit although the benefit is less than what some may think. It also comes at a price. When the family unit is reoriented toward social welfare goals, it can no longer serve its original purpose of perpetuating a genetic heritage.

Men born after 1939 - separation of sex from reproduction

In this cohort, good boys have once again been the top breeders. This might seem counterintuitive. After all, sexual morality has become even more liberal since the 1960s, and this change has paralleled a growing infatuation with thuggish males in popular culture. Yet something seems to have kept bad boys from translating their sexual success into reproductive success.

That "something" is easier access to contraception and ... Roe v. Wade. More and more good girls are making out with bad boys, but fewer and fewer are making babies with them.

Pro-lifers see this as proof that pro-choicers are secret eugenicists. I think it's just an unintended consequence. Paradoxically as it may seem, modern culture is favoring the reproduction of stable couples who plan for the long term and invest in their children. 

Just think. What is the core message of modern culture? It's live for today, live for yourself, and avoid long-term commitments, such as family and children. And who responds the most to that message? It's people whose time orientation is already focused on the present and who already invest as little as possible in their offspring. Modern culture is sterilizing those individuals who are most susceptible to its message.

And so, when it comes to having babies and raising them to adulthood, America's white middle class is slowly but surely closing in on first place (Frost, 2012).


Perhaps this is all for the best. What other choices are there? Conservative politicians talk a lot about traditional values, but not one in ten believe what they say. To judge by their personal lives, many seem happy with the current climate of sexual permissiveness. Anyhow, if conservatives really do try to turn back the clock, their efforts will be blocked by the libertarian right and the liberal left. And if they manage to outflank both groups, they'll be lucky to take us back to the policies and practices of the 1950s. Unfortunately, this is one case where half-measures will make things worse. We've come to where we are because of the 1950s. 

So what political option is left for someone like me? I wish to preserve our existing genetic heritage, if only because we don't fully understand what we are about to lose. If you feel the same way, the best course of action seems to be the present one of separating sex from reproduction. Call it "tactical liberalism" if you wish, but I see no other realistic alternative.


"Adoption" (2014) Wikipedia 

"Crime in Sweden" (2014). Wikipedia  

Frost, P. (2012). Obama: White America's bogeyman? Evo and Proud, November 24  

Gibson, K. (2009). Differential parental investment in families with both adopted and genetic children, Evolution and Human Behavior, 30, 184-189. 

JayMan. (2012). Some guys get all the babes - not exactly, JayMan's Blog, November 8 

Lalor, J.J. (1886). Cyclopaedia of Political Science, Political Economy, and of the Political History of the United States, Chicago: A.H. Andrews & Co.,+Political+Economy,+and+of+the+Political+History+of+the+United+States&ots=VqItRo_7kY&sig=aL3srydNpIpMoKOlKnd5gXqnp0g#v=onepage&q=Cyclopaedia%20of%20Political%20Science%2C%20Political%20Economy%2C%20and%20of%20the%20Political%20History%20of%20the%20United%20States&f=false  

Landes, D. (2008). Higher birth rates among Sweden's foreign born, The Local, November 3

Mednick, S.A., W.F. Gabrielli Jr., & B. Hutchings. (1984). Genetic influences in criminal convictions: evidence from an adoption cohort, Science, 224, 891-894  

"Minnesota Transracial Adoption Study" (2014), Wikipedia

Yao, S., N. Langstrom, H. Temri, and H. Walum. (2014). Criminal offending as part of an alternative reproductive strategy: investigating evolutionary hypotheses using Swedish total population data, Evolution and Human Behavior, in press

Saturday, August 9, 2014

The agricultural revolution that wasn't


Originally from south China, Austronesians spread successively outward to Taiwan, Southeast Asia, and Oceania. Was farming the secret of their success? Or was it their mental makeup? (source: French Wikipedia - Maulucioni)


About 10,000 years ago, the pace of human genetic evolution rose a hundred-fold (Hawks et al., 2007). Our ancestors were no longer adapting to slowly changing physical environments. They were adapting to rapidly evolving cultural environments.

What, exactly, caused this speed-up? The usual answer is the shift from hunting and gathering to farming, which in turn caused other changes. People were becoming sedentary and living in ever larger communities: villages, towns, and finally cities. Farming also produced a food surplus to be stored for future use, thereby providing powerful men with the means to bankroll a growing number of servants, soldiers, and other hangers-on. Thus began the formation of early states. And thus ended the primitive equality of hunter-gatherers.

But is that the whole story? Was farming the trigger for this chain of events? Or did something earlier get things going? More and more anthropologists are taking a closer look at what happened just before the advent of farming, a period called the "Broad Spectrum Revolution": 

All Paleolithic hominids lived by hunting and collecting wild foods, an aspect of existence that began to disappear only with the emergence of the farming and herding societies of the Neolithic ≤10,000 years ago (10 KYA). What are the roots of this remarkable economic transformation? The answer lies in equally revolutionary changes that took place within certain stone age cultures several millennia before. In 1968, Lewis R. Binford noted what appeared to be substantial diversification of human diets in middle- and high-latitude Europe at the end of the Paleolithic, roughly 12-8 KYA. Rapid diversification in hunting, food processing, and food storage equipment generally accompanied dietary shifts, symptoms of intensified use of habitats, and fuller exploitation of the potential foodstuffs they contained. (Stiner, 2001).

Farming thus came on the heels of a broader cultural, behavioral, and even psychological revolution. It is this broader change, rather than farming alone, that probably caused many supposedly farming-related events, such as the rapid spread of certain agricultural peoples into territories that formerly belonged to hunter-gatherers. Examples include the Bantu expansion, which began about 4,000 years ago along the Nigerian/Cameroun border and spread east and south, eventually throughout almost all of central, eastern and southern Africa. There was also the more controversial Neolithic expansion, which started about 10,000 years ago in present-day Turkey and pushed north and west into Europe. Finally, there was the Austronesian expansion, which began over 6,000 years ago when Malay-speaking farmers crossed from south China to Taiwan. Then, some 4,000 years ago, they began to push rapidly into Southeast Asia and Oceania, finally reaching places as far apart as Easter Island and Madagascar.

Farming is said to have fueled all three demographic expansions. It created more food, which in turn created more people, who then bulldozed the less numerous hunter-gatherers out of existence. Yet this theoretical model does not fit the Austronesian expansion very well, as anthropologist Roger Blench points out:

The [existing] model proposes that it was the Austronesian adoption of an agricultural package, including rice, pigs and chickens, which allowed them to colonise Island SE Asia at the expense of resident hunter-gatherers. However, archaeology has signally failed to confirm this model. Early sites show very similar dates across a wide geographical area, suggesting that the first phase of post-Taiwan Austronesian expansion took place extremely rapidly. Pigs, dogs and chickens have been shown to arrive in ISEA via other routes and rice is conspicuously absent in most places. This paper argues that this model has effectively inverted the actual situation, and that the Austronesian expansion was the consequence of a failed agricultural revolution and a reversion to opportunistic foraging. (Blench, 2014)

There was no "package" of domesticated plants and animals that enabled Austronesians to overwhelm the earlier inhabitants of Southeast Asia:

No remains of cereals of the relevant antiquity have been found in the Northern Philippines. Even today, the characteristic millets of the Asian mainland are barely represented in ISEA agriculture. Of the dogs, pigs and chickens originally thought to be part of the Austronesian 'package' only pigs cross the Taiwan Strait, and these now seem to be a local domestication not ancestral to the domestic pigs which are generally part of the Austronesian world. The apparent reconstructions for names of these domestic species formed part of the argument for their salience, but as Blench (2012) points out, these were based on chains of loanwords giving an appearance of spurious antiquity. (Blench, 2014)

Not only did the Austronesians bring a limited farming package to Southeast Asia, the existing peoples there already practiced a mix of farming and foraging:

Ellen (1988) describes this type of mixed vegeculture and arboriculture, a sedentary lifestyle based around sago extraction, for Seram in Eastern Indonesia. Stark (1996) touches on this hypothesis in a discussion of the archaeology of Eastern Indonesia, and Kyle Latinis (2000) discusses the broader role of arboriculture in early subsistence in ISEA. Hunt & Rushworth (2005) report evidence for disturbance in the tropical lowland forest at Niah, Sarawak, Malaysian Borneo at 6000 BP which they attribute to cultivation. Huw Barton (2012) has evidence from starch on stone pounders in the Kelabit highlands for palm granules earlier than 6500 BP. (Blench, 2014)

The incoming Austronesians really brought little, agriculturally speaking. In some cases, they actually reverted to foraging. In other cases, they adopted various crops and farm animals from the locals.

The picture is diverse, suggesting continued foraging, vegeculture, and sago starch extraction. Hence the concept that the maritime Austronesians reverted to a type of subsistence based on fishing, trading, possibly raiding and exchange of prestige goods. With their advanced sailing technology, they were well-placed to carry high-value goods from one exchange site to another. Their encounter with the Melanesian populations in Eastern Indonesia is certainly responsible for their adoption of vegeculture and domestic animals, but they were willing to drop and re-adopt these according to the circumstances of individual cultures they encountered. (Blench, 2014)

The Austronesians are often treated in the existing literature as a type-society for demographic expansion, with agriculture the underlying engine of growth. This is in increasing disaccord with the archaeology of the region, and this paper will suggest that the explanation is almost its inverse, that they succeeded precisely because they strategically reverted to foraging. (Blench, 2014)

What advantage, then, did the Austronesians have over the natives they displaced? There must have been something to offset the "home team" advantage of the natives, who knew the local environment better than anyone else. 

The Austronesian advantage seems to have been threefold: (1) a more flexible and innovative approach; (2) a less present-oriented time orientation that extended further into the past and the future; and (3) a less individualistic approach to life that made collective goods and goals more possible.

Flexibility and innovation

Blench (2014) states: “Austronesians quickly reinvented themselves, incorporating regional innovations into their cultural repertoire. Apart from their own distinctive pottery, they must have quickly seized on other early trade possibilities, obsidian, stone axes, woven goods and baskets. By the time they begin to reach uninhabited islands they have constructed Austronesian culture out of fragmentary elements adopted from a wide range of sources.”

Time orientation

The Austronesians saw themselves as the embodiment of lineages that stretched backwards into the past and forwards into the future. Preservation of genealogies seems to have been a typical cultural trait of Austronesian peoples, and this ancestor worship fostered a widespread desire among them to become revered ancestors. Quoting an earlier author, Blench (2014) points to "a culturally sanctioned desire to found new settlements in order to become a revered or even deified founder ancestor in the genealogies of future generations." The rapidity of the Austronesian expansion was thus, in part, ideologically driven.


Blench (2014) refers to "the striking differences between Austronesians in contact with Melanesians, whose typical social structures were individualist, acephalous and marked by great diversity in approaches to religion and belief." Austronesian society was more hierarchical with caste-like elements, particularly priestly castes who acted as repositories of esoteric knowledge. Belief-systems were more homogeneous. Austronesian peoples have long shown evidence of strong religiosity, even those who have not converted to Hinduism, Islam, or Catholicism.


One of my professors, Bernard Arcand, would talk to us about the hunter-gatherers of Upper Amazonia and their indifference to farming. They saw it as something akin to slavery and couldn't understand why anyone would want to stay put in one place and toil in the fields all day. Attempts to teach them the benefits of farming typically failed. Benefits? What benefits?

There has to be a change in mental makeup before farming becomes possible. People must become willing to exchange short-term pain for long-term gain. They must accept monotony and sedentary living. They must live in larger communities with people who are not necessarily close kin. And they must get used to bland, nutrient-poor food.

Anthropology has long tried to explain human societies in terms of their modes of subsistence: hunting and gathering, farming, industrial capitalism. This material basis of society is thus the source of our mental makeup. In reality, the two have coevolved with each other. Moreover, when humans adapt to a certain mode of subsistence, they may become "pre-adapted" to later ones. We associate the dawn of civilization with a shift toward future time orientation and a resulting complexification of technology, yet this shift seems to have first begun among hunter-gatherers of the sub-Arctic, where the yearly cycle required development of technologies for storage, meat refrigeration, and heat conservation, as well as other means to collect unpredictable and widely dispersed resources. This 'first industrial revolution' pre-adapted early modern humans for later cultural developments in places farther south. 

It is perhaps no coincidence that most of the human gene pool ultimately came from people who, more than 10,000 years ago, roamed the northern wastes of Eurasia. Such people were ancestral to many southward-pushing demographic expansions, including the one that would give rise to the Austronesians (Frost, 2014).



Blench, R. (2014). The Austronesians: An agricultural revolution that failed, To be presented at the Second International Conference on Taiwan Indigenous Peoples, 15-17 September 2014 Shung Ye Museum, Taipei, Taiwan

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

Frost, P. (2014). The first industrial revolution, Evo and Proud, January 18  

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

Stiner, M.C. (2001). Thirty years on the "Broad Spectrum Revolution" and paleolithic demography, Proceedings of the National Academy of Sciences, 98 (13), 6993-6996.

Saturday, August 2, 2014

Dear Fred

In a recent post, Fred Reed asks:

Why should I not indulge my hobby of torturing to death the severely genetically retarded? This would seem beneficial. We certainly don't want them to reproduce, they use resources better invested in healthy children, and it makes no evolutionary difference whether they die quietly or screaming.

The short answer is that any killing, for whatever reason, increases the likelihood of killing for other reasons. One exception is self-defence, but that's not done for pleasure. Another exception is capital punishment, but that, too, is not done for pleasure. More to the point, no single citizen can carry out an execution. It requires a lengthy judicial process. The same reasoning applies to the final exception of war. No single citizen can declare war.

It's not for nothing that killing is so taboo, especially recreational killing. Several things have contributed to the success of Western societies, but a leading one is the relatively peaceful nature of social relations. When people can go about their business without fearing for their lives, much becomes possible that otherwise would not be. This taboo is so crucial that we even extend it to nonhumans. Cats and dogs have no inherent right to life, yet it is a serious offence to torture them to death.

That's society. What about biology?

At this point, Fred may speak up: "But those are social reasons against killing of any sort. What are the biological reasons?"

The immediate biological reason is empathy. If I try to hurt someone, I feel the pain I inflict. Truth be told, the only life forms I enjoy killing are flies and mosquitoes. If a moth flies into our home, I'll go to some length to capture it and set it free outside, and I know others who do similar things. Just think of all the car drivers who come to a screeching halt to avoid running over some poor animal.

It's empathy that makes me and others act that way. And I cannot easily turn it off. It shuts down only when feelings of contempt enter my mind, as with those contemptible flies and mosquitoes.

Empathy is hardwired. It's 68% heritable in the case of affective empathy, i.e., the capacity to respond with the appropriate emotion to another person's mental state (Chakrabarti and Baron-Cohen, 2013). To date, studies have focused on disorders caused by too much empathy or too little. Psychopaths may have intact cognitive empathy, but impaired affective empathy. They keenly understand how others feel without actually experiencing those feelings. The reverse impairment may affect autists. As for depressives, they may suffer from being too sensitive to the distress of others and to guilt over not helping them enough. 

These disorders exist at the tail ends of a normal distribution. By focusing on these extremes, we forget the variability among healthy individuals. We all vary in our capacity for empathy, just as we do for almost any mental capacity.

How can evolution explain empathy?

Why do we feel empathy? How could natural selection favor such selflessness? This is of course the point that Fred is trying to make. Empathy keeps us from doing things that supposedly make evolutionary sense. Therefore, it could not have evolved. It must have been given to us by a Great Designer.

But why did this Great Designer give more of it to some people than to others? We're talking about a heritable trait. It's not as if everyone starts off the same way, with some later falling behind through their own wrongdoing.

And how has the Great Designer preserved this selfless behavior? Unless something is done, empathic people will eventually be overwhelmed by a tidal wave of cheaters, free riders, and people shouting "Gimme! Gimme! Gimme!" This is as much a mystery for creationists as it is for evolutionists. It's one thing to explain how altruism came to be. It's another to explain how it manages to survive in this cynical world.

These questions passed through my mind when I was going through my late mother's effects. I discovered she had for years been donating money for various projects in the Third World, at a time when she was a widow with no pension. Meanwhile, as a teenager, I had to take on all kinds of odd jobs to help us make ends meet. Looking over those donor receipts I shook my head and felt some resentment. How do good Christians like her manage to survive?

Yet she did, like others before her. For one thing, she was suspicious of strangers, and this suspicion extended to some ethnic groups more than to others. She was prejudiced and "postjudiced." If someone acted dishonestly with her once too often, she would have no more to do with him or her. Such people were "contemptible."

Today, that sort of behavior might seem un-Christian. But her Christianity was of an older, judgmental sort, being inspired more by the punitive Old Testament than by the forgiving New Testament. She would judge people, and her judgment could be harsh, very harsh.

Over space and time

Just as the capacity for empathy varies from one individual to another, it also varies statistically from one human population to another, being strongest in the "guilt cultures" of Northwest Europe. Guilt is the twin sister of empathy. Both flow from a simulation of how another person thinks or feels (an imaginary witness to a wrongdoing, a person in distress) and both ensure correct behavior by inducing the appropriate feelings (anguish, pity).

Why are guilt and empathy so strong in Northwest Europeans? Other societies ensure good behavior by relying on close kin to step in and enforce social rules. This policing mechanism has been less effective west of the Hajnal line (which runs roughly from Trieste to St. Petersburg) because kinship ties have been correspondingly weaker. There has thus been stronger selection for internal means of behavior control, like guilt and empathy.

This zone of relatively weak kinship is associated with unusual demographic tendencies, called the Western European Marriage Pattern:

- relatively late marriage for men and women

- many people who never marry

- neolocality (children leave the family household to form new households)

- high circulation of non-kin among different households (Hajnal, 1964; ICA, 2013)

The Western European Marriage Pattern was thought to have arisen after the Black Death of the 14th century. There is now good evidence for its existence before the Black Death and fragmentary evidence going back to 9th century France and earlier (Hallam, 1985; Seccombe, 1992, p. 94). Historian Alan Macfarlane likewise sees an English tendency toward weaker kinship ties before the 13th century and even during Anglo-Saxon times (Macfarlane, 2012; Macfarlane, 1992, pp. 173-174). I have argued that this tendency probably goes still farther back (Frost, 2013a; Frost, 2013b).

Whatever the ultimate cause, Northwest Europeans seem to have been pre-adapted for later shifts away from kinship and toward alternate means of organizing social relations (i.e., ideology, codified law, commerce). This tendency has taken various forms: the intense guilt-driven Christianity of the Anglo-Saxon penitential tradition and, later, Protestantism; the medieval alliance between Church and State to pacify social relations; and the post-medieval rise of the market economy. This cultural evolution has been described by the historical economist Gregory Clark for the English population between the 12th and 19th centuries. As England became a settled society, success went to those who could resolve disputes amiably and profit from thinking ahead—in short, those who had middle-class values of thrift, foresight, self-control, nonviolence, and sobriety. This English middle class, initially tiny, grew in numbers until its lineages accounted for most of its country’s gene pool (Clark, 2007; Clark, 2009a; Clark, 2009b).

But what does that have to do with evolution???
At this point, Fred may again speak up, with more than a touch of exasperation: "You're ducking my question! You're talking about culture, society, and religion! What does that have to do with evolution???"

Everything, Fred. Everything. Unlike other animals, humans have to adapt not only to their physical environment but also to their cultural environment. In short, we've become participants in our own evolution. We have domesticated ourselves.

Let me return to your initial question. What's to stop you from torturing to death the severely retarded? First, your sense of empathy should. If it doesn't, you're the one with a severe mental defect. I wouldn't want you as a fellow citizen, let alone as a neighbor. The law of the jungle may give you the right to torture defenceless people to death, but it also gives me the right to organize a lynch mob and hang you from the nearest tree.


Chakrabarti, B. and S. Baron-Cohen. (2013). Understanding the genetics of empathy and the autistic spectrum, in S. Baron-Cohen, H. Tager-Flusberg, M. Lombardo. (eds). Understanding Other Minds: Perspectives from Developmental Social Neuroscience, Oxford: Oxford University Press.

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

Clark, G. (2009a). The indicted and the wealthy: Surnames, reproductive success, genetic selection and social class in pre-industrial England.

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

Frost, P. (2013a). The origins of Northwest European guilt culture, Evo and Proud, December 7 

Frost, P. (2013b). Origins of Northwest European guilt culture, Part II, Evo and Proud, December 14

Hajnal, John (1965). European marriage pattern in historical perspective. In D.V. Glass and D.E.C. Eversley (eds). Population in History. Arnold, London.

Hallam, H.E. (1985). Age at first marriage and age at death in the Lincolnshire Fenland, 1252-1478, Population Studies, 39, 55-69. 

ICA (2013). Research Themes - Marriage Patterns, Institutions for Collective Action  

Macfarlane, A. (1992). On individualism, Proceedings of the British Academy, 82, 171-199.  

Macfarlane, A. (2012). The invention of the modern world. Chapter 8: Family, friendship and population, The Fortnightly Review, Spring-Summer serial

Seccombe, W. (1992). A Millennium of Family Change. Feudalism to Capitalism in Northwestern Europe, London: Verso.