Friday, February 11, 2011

Rethinking intelligence and human geographic variation

Children making pillow lace for a home workshop. Germany, 1847. During the early stages of Europe’s market economy, successful entrepreneurs would expand their workforce by having more children.

There are several obstacles to our understanding of geographic variation in human mental performance.

First, the subject is taboo. When people do discuss it, they often resort to euphemisms, “code words,” and the like. The result, all too often, is confused thinking. When ideas cannot be expressed clearly, the resulting theory is likewise obscure.

Second, there has been a tendency to imitate the physical sciences by seeking a “unified theory,” i.e., Phil Rushton and r-K life history theory (Rushton, 2000), Ed Miller and parental investment (Miller, 1994), etc.

There is indeed a unified theory. It’s called evolution by natural selection. But natural selection acts in many different ways in many different environments. This could hardly be less true for our species, which has had to adapt to a wide range of physical environments—from the tropics to the arctic—and a wide range of cultural environments—from nomadic hunter-gatherers to socially complex urban civilizations.

Third, until recently, human evolution was supposed to have happened a long time ago, surely no later than the Pleistocene. Our mental traits, like all other traits, are thus a product of ancient environments, when humans lived by hunting and gathering. As for all of the later developments—agriculture, civilization, literacy, State societies, class stratification—these things have shaped us culturally but not genetically.

Well, they have shaped us genetically. Changes to the human genome have accelerated over the past 40,000 years and especially over the past 10,000 years (Hawks et al., 2007). We are a young species. Human nature—or rather natures—is largely post-Pleistocene.

Recent selection

Thus, one theoretical model cannot account for all or even most variation in cognitive capacity among present-day humans. The higher IQ of East Asians, for example, almost certainly came about during historic times and was probably favored by the widespread use of exams as a means of social advancement. Likewise, the higher IQ of Ashkenazi Jews and other European populations is probably post-medieval in origin and driven by the high fertility of successful entrepreneurs, particularly those in cottage industries who could expand their workforces only by having larger families (Frost, 2007).

Another relevant factor is the rise of the State, particularly its monopoly on violence (Frost, 2010). This is discussed with respect to English society in Gregory Clark’s Farewell to Alms. Clark (2007) argues that the slow but steady demographic expansion of the English middle class from the 12th century onward gradually raised the population mean for predispositions to non-violence, deferment of pleasure, and other future-oriented behavior. Although the embryonic middle class was initially a small minority in medieval England, its descendants grew in number and gradually replaced the lower class through downward mobility. By the 1800s, its lineages accounted for most of the English population.

This natural selection came to an end with the Industrial Revolution. Previously, successful entrepreneurs expanded their workforce primarily by having larger families. With the decline of cottage industry and the commodification of labor, it became possible to hire workers on a large scale. Henry Ford was a successful businessman, but his economic success did not translate into reproductive success. He had only one child.

No-so-recent selection

Even further back in time, neither Rushton’s model nor Miller’s fits all of the facts. Yes, cognitive capacity does seem to show some kind of relationship with family structure, specifically low incidence of polygyny and high paternal investment. I am not convinced, however, that this relationship is best understood in terms of K-type versus r-type reproductive strategy.

Today, most of the human gene pool is derived from populations that only 15,000 years ago were confined to the northern tier of Eurasia. These populations have since expanded southward into temperate and even tropical Eurasia, as well as Oceania and the Americas. In the process, they have displaced other populations that were nonetheless better adapted in terms of climate and ecology.

What was their competitive advantage? It could not have been a K-type reproductive strategy. If we look at present-day hunter-gatherers from the northern arctic and sub-arctic, we find that they pursue a moderately r-type strategy despite high levels of paternal investment. Traditional Inuit, for instance, have short inter-birth intervals, with menstruation being a rare occurrence.

The competitive advantage seems to involve three characteristics of ancestral northern Eurasians:

1. A predictable yearly cycle, which favored the ability to plan ahead and make future decisions in the present. Indeed, early modern humans had more complex tools and weapons at arctic latitudes than at tropical latitudes, apparently because of the yearly cycle of resource availability: “Technological complexity in colder environments seems to reflect the need for greater foraging efficiency in settings where many resources are available only for limited periods of time.” (Hoffecker, 2002, p. 135)

2. A low incidence of polygyny, which reduced male-male competition for mates and the consequent disruptive effects on social organization.

3. A high level of paternal investment in the family, which in turn emancipated women from food provisioning and enabled them to develop a ‘family workshop’ of garment making, structure building, food processing, etc. (Kelly 1995, p. 262-270).

These northern Eurasians were thus mentally pre-adapted, despite their simple social organization, for later technological developments, even though such developments were possible only in more southern environments for which these populations were less ecologically adapted. It is perhaps no surprise that they were able to expand southward into the temperate and tropical zones, eventually peopling almost all of Eurasia, Oceania, and the Americas.

References

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

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

Frost, P. (2007). Natural selection in proto-industrial Europe, Evo and Proud, November 16.
http://evoandproud.blogspot.com/2007/11/natural-selection-in-proto-industrial.html

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 Science USA. 104, 20753-20758.

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

Kelly, R.L. (1995). The Foraging Spectrum: Diversity in Hunter-Gatherer Lifeways. Washington, D.C.: Smithsonian Institution Press.

Miller, E. (1994). Paternal provisioning versus mate seeking in human populations, Personality and Individual Differences, 17, 227-255.

Rushton, J.P. (2000). Race, Evolution, and Behavior, 3rd edition, New Brunswick, NJ: Transaction.

22 comments:

J said...

Well, Evo, you have debunked the paleodiet. I think you are basically right.

Faultfinding:

(1) What is that illusion the Northern Europeans filled Earth? We are less than 20% of humanity. And shrinking.

(2) The chinese did practice the exam system but its evolutionary impact cannot be so important. There were too few mandarins (less than 0.1% of the population) for that, and too many Manchu princes and military other conquerors.

Tod said...

"Beginning as early as the 12th century, some of the common fields in Britain were enclosed into individually owned fields" British Agricultural Revolution.

The process of enclosure of land (which only fully took place in Britain) must have led to the demographic decline of the peasant class.

Clark (2007) argues that the slow but steady demographic expansion of the English middle class from the 12th century

Hmmm, isn't that about the time that England's own 'denizens of Westmount' took an extended vacation.

Anonymous said...

The chinese did practice the exam system but its evolutionary impact cannot be so important. There were too few mandarins (less than 0.1% of the population) for that, and too many Manchu princes and military other conquerors.

I agree with this objection, but it is important to consider how many of the gentry, who did not obtain government jobs there were - men who attempted the exam, did not succeed, did not obtain positions within the government, yet who were still able by virtue of their eduction to become part of the landowning class.

However, I think this must surely have been marginal, as Japan which was never under such a Mandarin system does not seem to lag in terms of IQ compared to China.

Michael said...

@J

The northern peoples filling the Earth that Peter refers to include East Asians:

"When the glaciers began their final retreat 15,000 years ago, the former northerners in both halves of the Eurasian continent would have recolonized the abandoned latitudes. In this way both Europe and East Asia would have been dominated by peoples originating from groups that 5,000 years earlier had been small populations at some northern extremity of the human population range"

Nicholas Wade, Before The Dawn: Recovering the Lost History of Our Ancestors (New York: Penguin, 2006), 101.

Anonymous said...

The problem with the argument you advance for Chinese higher average IQ is that the Japanese seem to also have similarly higher average IQs with similar distributions.

There does not seem to have been an equivalent of the Imperial exam system in Japan, yet they acquired similarly high average visuospatial skills.

Anonymous said...


3. A high level of paternal investment in the family, which in turn emancipated women from food provisioning and enabled them to develop a ‘family workshop’ of garment making, structure building, food processing, etc. (Kelly 1995, p. 262-270).


Does the reference explain what they mean by structure building?

In my experience, very few women are capable of putting structures together.

Tod said...

(G.Cochran brought up the Japanese objection in a comment at Mangan's)

The Japanese didn't have examinatiions but they did have a Malthusian problem; there was not enough to eat (The Chinese called them "shrimp barbarians" and "dwarf pirates"). The stupidest Japanese just starved so there was probably a kind of culling of the lower orders rather than selection of the most intelligent in Japan. I believe very high IQs are not as common in Japan as the average IQ in Japan would suggest.

Sky high IQ's ought to be much more common in China than in Japan; are they?

I think the main reason why the Chinese got high IQ's in historical times was no 'Rhodesians!' The Chinese' didn't persecute 'Rhodesians' who settled in China they just blandly declined to borrow at interest from them. Those Chinese who benefited from a examination success did not have a caste of endogamous outsiders monopolizing the intellectually demanding work. Chinese spread their higher IQs to the rest of the population (though writing a successful three legged essay) because the niche for intellectually capable administrators in China was filled by any Chinese who was clever enough.

India has low average IQ because it is a stratified society, there was a caste for every job and the IQ increases didn't spread.

Peter Frost said...

J,

The Chinese civil service exam had three levels. Those who passed all three levels became mandarins, but tangible benefits and improved social status accrued even to people who passed only the first (local prefecture) level.

These civil service exams were adopted by Korea and Japan, but to a lesser extent. The "exam culture," however, was much more pervasive, and seems to have been a long established characteristic of East Asian societies.

I'll write about this subject in a subsequent post.

Tod,

The decline of England's peasantry was due to several factors:

1. The Black Death and its disruptive impact on feudalism.

2. The subsequent rise of the yeomanry (free farmers) and their growing political and cultural impact.

3. Enclosure of land and migration to industry towns.

The ultimate cause was the development of a high-trust society that made feudal social relations unnecessary. People were emancipated to act as autonomous agents in a free market economy.

Presumably, as we move back to a low-trust society, we'll see a re-emergence of "neo-feudalism."

Michael,

Interesting quote. Sounds familiar ...

Anon,

Structure building refers to the building of homes and other structures. Yes, home building used to be "women's work."

Tod,

Japan had the same emphasis on literacy and knowledge of classical literature as criteria for social promotion. Of course, the same was true for Europe. Unfortunately, the "winners" in the European system became monks, at least until the Reformation.

Anonymous said...

That work by Kelly seems to be about Hunter Gatherers, and so he is perhaps referring to female involvement in building shelter ...

Perhaps we just have different definitions of structures ...

But then, some people regard an abacus as a computer.

Anonymous said...

Working in Silicon Valley as I do, what is interesting is the racial groups you find doing software development. There are also further divisions when it comes to kernel work vs user-level work. There are also interesting differences in female participation.

There is a heavy concentration of white males, but there are many Chinese and Indian males as well. Depending on the company, you might not find white males in the majority, but they are often the largest single group.

There are usually no Mexicans at all in the field and very few African Americans.

When it comes to females, Chinese females predominate, followed by Indian females and Eastern European females. White females are highly under represented.

Stephen said...

The introduction of iron to Japan coincided with a large influx of Chinese people and culture. But didnt eunachs monopolise the top jobs in China.

Anonymous said...

I suspect that the critical issue here is maturation rates. Specifically, accelerated maturation vs delayed maturation.

I think Rushton has already hinted at this.

In an environment with high pathogen load, it is advantageous to reach reproductive maturation earlier, although there is a limit, of course.

In environments with lower pathogen load but complex environmental problems, it makes sense to mature later so that more somatic development can occur, and in some places, brain development becomes important. Perhaps in some places, there has been an arms race, as larger brains lead to more complex cultures, which ...

Anonymous said...

Presumably, as we move back to a low-trust society, we'll see a re-emergence of "neo-feudalism."

I've heard this term "neo-feudalism" a few times in the media recently.

I'd be interested to hear your thoughts about it. I thought your posts on China and "the end of history" and your views on the coming near future were extremely interesting. I wonder how you think "neo-feudalism" fits into this projection.

Anonymous said...

Anon,

I know a number of software companies in Quebec City. The employees tend to be younger people who had trouble finding employment in heavily unionized industries (e.g., the civil service). Women tend to predominate in managerial positions while men do the actual programming.

Stephen,

No, the top jobs generally went to the Mandarins, i.e., those who passed the third level of the civil service exam.

Anon,

Is that hypothesis true for non-human animals? It seems to me there are many slowly developing organisms in regions with high pathogen load.

Anon,

Neo-feudalism will come about through a devolution of power to the municipal level or even to civil society (churches, private clubs, neighborhood associations, ethnic organizations, etc.). The immediate cause will be the high debt burden (or even insolvency) of higher levels of government. A less immediate cause will be a perception that higher levels of government are parasitic or even hostile to one's values.

Neo-feudalism will create islands of high trust in an otherwise low-trust world. People will tend to retreat to these islands where they will do most of their work and social activity. This process will become self-reinforcing, with the result that neo-feudal domains will be surrounded by depopulated areas that people will avoid even though the risk to life may not be that great.

Anonymous said...


Is that hypothesis true for non-human animals? It seems to me there are many slowly developing organisms in regions with high pathogen load.


Actually, you are correct. The hypothesis about selection for earlier or later maturation has no need for pathogen load.

In an environment where females can pretty much provision their offspring themselves, it would seem to me that there would be intense selection for earlier maturation and for males to be able compete with other males.

Thus, later maturation is a reproductive disadvantage.

In an environment where females need make assistance in provisioning their offspring, later maturation becomes more competitive.

Living in California as I do, one of the funniest things is seeing AfAm kids juxtaposed with Chinese kids.

The AfAm kids have tiny heads on top of better developed bodies. The Chinese kids have enormous heads on relatively less developed bodies.

Kiwiguy said...

Peter,

Just regarding East Asians, Steve Hsu has posted an old unpublished paper by Ron Unz entitled 'Preliminary notes on the possible sociobiological implications of the rural Chinese economy'. It is along similar lines to Greg Clark's work.

http://infoproc.blogspot.com/2011/02/sociobiological-implications-of.html#

Tod said...

They might not make better farmers or traders but going by Nobels for physics the Japanese are every bit as clever as the Chinese - and them some.

Yukawa and Tomonaga were from families with a background in traditional scholarship. Physicists like Unz and Hsu must be puzzled that the Chinese with a historically formal system of examinations are not outdoing the "dwarf pirates" who just copied Chinese culture.

I think there was a Malthusian aspect to Japanese IQ advantage, or maybe it was marrying their relatives or maybe it is just all that fish.

Tod said...

Japanese Nobels for physics suggest Unz is wrong about the Chinese having an advantage over the 'dwarf pirates'.

Ben10 said...

I'm still upset having been lectured about the taysachs in quebec 'obvioulsy caused by selective pressure to increase IQ', just to have the next post questioning this relation.I guess in this second post i would have been lectured that 'it obviously has nothing to do with selective pressure to increase IQ'. Anyway.

I believe that asians and occidentals might reach the same numerical performances as measured by IQ, or about the same, but their way of thinking is radically different in some, not all but some, issues.

Tod said...

Michio Kaku is smarter than Hsu or Unz but they are all out of their depth.

Why do physicists think they are masters of all sciences?

Anonymous said...

Do you really think using the phrase, "human geographic variation" solves anything? Or is elucidating?

Kiwiguy said...

A new paper on 'human behavioural diversity':

Brown, et al., 2011. Evolutionary accounts of human behavioural diversity

More controversial is the idea that betweenpopulation
differences in genetic complement underlie a portion of cross-cultural variation in behaviour...

Moreover, analyses have shown that recent human
evolution is dominated by partial selective sweeps
that are specific to particular geographical regions or
populations [90]. These data suggest that there are significant
genetic differences between human populations that have arisen from recent selective events, with much
of the variation fairly broad scale (e.g. continent wide)
[91]. While some researchers have acknowledged genetic variation as a potential source of cross-cultural variation in behaviour (e.g. [59,62]), between-population
genetic variation has yet to be incorporated fully into the human evolutionary behavioural sciences.
The failure to incorporate the findings of human population
genetics is a serious inadequacy of the human evolutionary behavioural sciences and currently limits our understanding of behavioural diversity."

Evolutionary accounts of human behavioural diversity (Phil. Trans. R. Soc. B 2011 366, 313-324
Brown et al)

http://lalandlab.st-andrews.ac.uk/pdf/Publication156.pdf