A correction from *Nature*

Corrected:    In the original text, we wrongly attributed to Enrico Spolaore the opinion that using genetic data in economics could help policy-makers to set immigration levels. He actually suggested that the work could reduce barriers to the flows of ideas and innovations across populations. The text has been amended to reflect that.

The link is here.  The earlier MR post is here.  I thank a loyal MR reader for the pointer.


Thank you, Tyler, for posting the correction. If people would like to read more on this topic, Romain Wacziarg and I discuss possible policy implications of recent research on long-term determinants of development in the paper "How Deep are the Roots of Economic Development?" , forthcoming in the Journal of Economic Literature:


I was very happy to learn that our paper is now covered in a video up at MRUniversity.com, under the geography section of their development economics class. Thanks and keep up the great work at MRUniversity!

Just regarding the Gregory Clark work, there is another example of that pattern in China. From Professor Steve Hsu's blog:

"The comparison of Beijing nobility and Liaoning peasants is drawn from Lee and Wang’s (1999) survey of Chinese demography, which, in turn, is based on a very detailed investigation of population in Liaoning by Lee and Campbell (1997). In Liaoning, all men had military obligations and were enumerated in the so-called banner roles, which described their families in detail. Individuals’ occupations were also noted, so that fertility can be compared across occupational groups. High status, high income occupations had the most surviving sons: for instance, soldiers aged 46–50 had on average 2.57 surviving sons, artisans had 2.42 sons, and officials had 2.17 sons. In contrast, men aged 46–50 who were commoners had only 1.55 sons on average."


Also, see Rindermann's papers on smart fractions and Haplogroups as evolutionary markers of cognitive ability may be of interest.

Wow, that is truly Romneyesque. Is Nature retroactively gettting it right, or proactively getting it wrong?

No need to take bets on how certain posters will respond to Nature's correction, with many insisting that simply changing someone's words to reflect their actual view is no reason for them to change their thinking.

How is it Romneyesque exactly?

And if their thinking is independent of this person's words, then any change to the words will have no effect on the thinking. I didn't see anyone saying that this guy had influenced their opinion in any way.

Enrico Spolaore, what do you think of Steve Sailers criticism of your lack of understanding on the genetics front? BTW, this was also echoed by Greg Cochron. But to be fair, Greg didn't specifically endorse Steve's criticism; he just said you guys clearly don't understand genetics.

The controversy reported in Nature, and commented by Sailer, Cochrane and others, is about the use and interpretation of measures of genetic diversity WITHIN populations. In my work (with Romain Wacziarg), we have not used genetic diversity within populations, but genetic DISTANCE BETWEEN populations. And yes, economists know that these measures are based on neutral genes.. As we wrote in our article "The Diffusion of Development" in the Quarterly Journal of Economics (2009):

"genetic distance measures the difference in gene distributions between two populations, where the genes under considerations
are neutral—they change randomly and independent of selection pressure. The rationale for this approach is that divergence
in neutral genes provides information about lines of descent. Most random genetic change takes place regularly over
time, as in a molecular clock. Therefore, genetic distance measures the time since two populations have shared common ancestors— that is, the time since they have been the same population. In other words, genetic distance is a summary measure of general relatedness between populations. [...] Because genetic distance is based on neutral change, it is not meant to capture differences in specific genetic traits that directly matter for survival and fitness. Hence, our results provide no evidence
for a direct effect of specific genes on income or productivity. Our findings are not about some societies having some specific
genes that make them directly richer. Instead, our results provide strong evidence that a general measure of genealogical relatedness between populations can explain income differences today, even though it reflects mostly neutral genetic variation. Why? Our interpretation is that genetic distance captures barriers the diffusion of development. More closely related societies are
more likely to learn from each other and adopt each other’s innovations. [...] Populations that share more recent common ancestors have had less time to diverge in a wide range of traits and characteristics that are transmitted across generations with variation. Of course, in human populations many of those traits are transmitted across generations culturally rather than biologically. Similarity in such traits would tend to facilitate communication and understanding, and hence the diffusion and adaptation of complex technological and institutional innovations."

tothe above cited paper "How Deep Are the Roots of Economic Development?" if you want to learn more about this research.

I quite approve of Dr. Spolaore's use of differences in neutral genes as a clever way to measure the effectiveness of pre-Columbian barriers to diffusion of technology, culture, and people. Unfortunately, Ashraf and Galor and many of their supporters and critics are using Spolaore's concept more carelessly.

Consider the example from Ashraf and Galor's abstract about how Bolivia is the most genetically homogeneous country and Ethiopia the most genetically diverse.

The germ of a true idea in this is that in 1491, the population of what is now Bolivia were descendants of people who had gone through a series of genetic bottlenecks as humans expanded Out of Africa. So the indigenous population of the Altiplano had less diversity of neutral or junkish genes that aren't strongly acted upon by natural selection. (These are the genes that population geneticists such as Cavalli-Sforza focus upon since they don't do all that much, so they tend to be passed on by predictable rules of randomness. In contrast, functional genes can prove to be favorable or unfavorable mutations and can spread wildly or die out quickly.) This does _not_ mean that South American indigenes necessarily had less diversity of functional genes.

In contrast, Ethiopia is back near where the modern human race presumably got started, so it's population didn't have to go through various bottlenecks such as Out-of-Africa and Into-America.

In reality, this is an overly stylized notion about Ethiopia since even in 1491 some of the Abyssinian highlands were populated by a clearly mixed race black and white population reflecting movements back and forth across the Red Sea, with the highlands of Ethiopia and the highlands of Yemen sharing a not wholly dissimilar and not wholly unconnected culture for thousands of years. The Abyssinians themselves claim to be the descendants of the son of the Queen of Sheba, who was presumably from the Arabian peninsula. (Arabs are mostly descended from people who went through the Out of Africa bottleneck, thus reducing their neutral gene diversity.) Moreover, Abyssinians were in occasional contact with other Old World civilizations -- in 1306, for example, Emperor Wedem Ar'ad of Ethiopia sent a diplomatic mission that called upon Pope Clement V at his palace in Avignon seeking an alliance of Christians against Muslims.

On the other hand, population geneticists don't really like to sample in cosmopolitan cities like Addis Ababa, even though that's where most of the population is today. They prefer to get their samples in isolated tribal settings, of which Ethiopia has an abundance in some of its more remote regions, especially in the western lowlands. These tend to display a lot of neutral gene diversity since their ancestors have mostly been there for a very, very long time.

In any case, the basic idea is that Ethiopia is back near where the modern human Out of Africa expansion began and Bolivia near the far end. So, that implies that it was particularly difficult before intercontinental sea travel became reliable for valuable innovations to diffuse from Ethiopia to Bolivia or vice-versa. For example, the Bolivian potato is a highly useful crop, but before Columbus it was unlikely to get to Ethiopia because it's an awful long walk.

Now, you could argue that we pretty much already knew that and therefore we don't need Spolaore's genetic distance measures derived from Cavalli-Sforza. But, it's an elegant way to quantify a whole lot of otherwise murky prehistory.

Where it goes wrong is that people always forget that population geneticists, who are trying to figure out the genealogies of racial groups, prefer to look at mutations in the most neutral, least important genes available. So, when everybody today passes on the urban folklore about how there is the most genetic diversity in Africa, yes, that's true about genes that don't do much of anything. But, if you are interested in diversity of genes that do matter, well, then you've got a very methodologically tricky issue on your hands.

For example, consider Bolivia, which was indeed relatively homogeneous in 1491 in neutral genes. Yet, there already existed economically important genetic diversity in functional genes. The Amerindians of the Bolivian highlands often possessed a favorable mutation adapting them for living and reproducing at high altitude which the Amerindians of the Bolivian lowlands did not possess. To this day, Altiplano Indians find the Amazon region physically uncomfortable and Amazonian Indians find the Highlands uncomfortable.

This mutation for thriving at high altitude in the Andes has been identified (interestingly, it differs from the Tibetan equivalent). Presumably, Ethiopian highlanders also have some kind of genetic traits that let them do well in thin air too (as their Olympic distance running success suggests), but last I checked the precise genes haven't been identified yet.

I did not criticize for this Dr. Spolaore, whose most recent paper I quite like, I criticized Ashraf and Galor's current paper:


It's always a shocker when economists don't comprehend genetics, the history of ideas, statistical inference, Darwinian biology, non-linear dynamics, global brain theory, the philosophy of science, sociology, anthropology, etc.

Always completely unexpected.

Here's one abstract of the Ashraf-Galor paper that is at the center of this latest brouhaha, with the Harvard Anthropology department and Nature on the politically correct warpath against the two economists and anybody else they can drag in, such as poor Dr. Spolaore. So, read this over and then I'll make a few general suggestions for economists.

The Out of Africa Hypothesis, Human Genetic Diversity, and Comparative Economic Development

Quamrul Ashraf and Oded Galor

Forthcoming in the American Economic Review


This research advances and empirically establishes the hypothesis that, in the course of the prehistoric exodus of Homo sapiens out of Africa, variation in migratory distance to various settlements across the globe affected genetic diversity and has had a long-lasting hump-shaped effect on comparative economic development, reáecting the trade-offs between the beneficial and the detrimental effects of diversity on productivity. While intermediate levels of genetic diversity prevalent among Asian and European populations have been conducive for development, the high diversity of African populations and the low diversity of Native American populations have been detrimental for the development of these regions.

Obviously, Ashraf and Galor's abstract is kind of dopey. They just sort of lost track at some point of Spolaore's key point that he's focusing on neutral gene diversity. But their angry critics in Harvard anthropology department are equally dopey: instead of dismissing the paper for its technical confusion, they are denouncing Ashraf and Galor for being evil.

Here are a few general lessons from this fiasco for economists:

- Economists are increasingly tempted to try to make use of the ever growing piles of data related to genetics, and that's perfectly natural and rational.

- Yet, the hysteria and thuggish of the Thought Police Volunteer Auxiliary remains unchecked, as poor Dr. Spolaore's wholly justified fear of being associated with crimethink suggests.

- So, it seems only logical that if you are going to venture into topics where you expose yourself to hatred and calumny, you should check your work carefully to make sure you are going to be hated for telling the truth, rather than to go through all the bother of being hated over something where your position is woozy.

- Yet, how do you get started coming up with new and true ideas in the human sciences? You might naively assume that you should read famous authors like Stephen Jay Gould, Jared Diamond, Daron Acemoglu, and the like. But, many of the most celebrated brand names are celebrated precisely for their ignorance, malevolence, foolishness, or disingenousness. For example, Diamond's books can be highly valuable to the well-informed critical reader, but the naive tend to take away only Diamond's moneymaking preaching-to-the-choir bits.

- Or you can read the works of sincere, careful scholars, such as Dr. Spolaore, who are trying to push the ball forward on some key concepts (such as the importance of long-term genealogical relatedness in Dr. Spolaore's case), without getting themselves James Watsoned or Larry Summersed. This is an excellent suggestion, but it helps to have a handle on the issues first. The good guys' need to not ruffle feathers also means it can be hard for newcomers to grasp important lessons from their cautious prose.

- Fortunately, there's a small corner of the Internet -- just google "human biodiversity" -- where big issues in the human sciences are publicly debated in a no holds fashion. Just pick a pseudonym and try out your idea. Newcomers can get schooled there quickly. Ashraf or Galor might have had their feelings hurt if they'd first tried out their Out-of-Africa genetic diversity brainstorm on Cochran or Razib, but they'd probably have come up with better ideas by now if they hadn't wasted so much time on it.

Steve, you got it wrong, yet again! Perhaps you should allocate some of your time to reading rather than posting foolish uniformed remarks.. Ashraf and Galor explain quite clearly in their paper that apparently you have never read, and in their response letter as well, that they use neutral genes. But that diversity in these neutral genes is correlated with diversity in genes that do have phonotypical expression.

"A careful reading of our research should make it apparent that our use of the measure of genetic diversity from the field of population genetics does not imply that our hypothesis is one of biological determinism, nor does it imply that DNA material is directly important for economic outcomes or that some genes are more important than others for economic success. The fact that the measure of genetic diversity we use is based on variation across individuals in non-protein- coding regions of the genome (and, thus, in genomic characteristics that are not necessarily phenotypically expressed so as to be subject to the forces of natural selection) is clear reason why our findings should be interpreted through the lens of our measure serving as a proxy for diversity more broadly defined.

The more relevant question to ask therefore is to what extent the measure we use can reasonably be considered a proxy for diversity in unobserved phenotypic or socially-constructed characteristics. There is indeed an emerging body of scientific evidence that establishes remarkable correlations in this regard. For instance, in articles published in Science and Nature in the past few years, researchers have shown that variation in migratory distance from East Africa, which explains global spatial variation in genetic diversity across populations (due to what population geneticists call a serial founder effect of the prehistoric “out of Africa” migration process), also happens to explain global spatial variation in phonemic diversity across languages (Atkinson, Science, 2011) as well as variation in observable phenotypic characteristics across populations (Manica et al., Nature, 2007). In other words, the scientific evidence suggests that the “out of Africa” migration process generated not only variation in the measure of genetic diversity that we employ but also correlated shifts in other dimensions of diversity. It is remarkable that the “out of Africa” migration has left its mark on all these dimensions of diversity, one that persists to the present day despite tens of thousands of years of population mixings in both biological and cultural dimensions. Indeed, it is this very mark that we exploit in our research in order to overcome statistical issues of reverse causality."

Once again, how is Bolivia the most genetically homogeneous country in the world in an economically meaningful sense?

That's a simple reality check.

Spolaore knows what he's talking about, but Ashraf and Galor keep getting themselves confused.

If Sailer weren't in the middle of this argument, it would be a pretty funny story of misguided analysis attacked for the wrong reasons. Less than stellar thinking all the way round.

How come no one accuses Peter Bauer of racism when he repeatedly states that development depends on, among other factors, the "attitudes and aptitude" of people, and suggests that economic underdevelopment is reflected in cultural underdevelopment too?

Shhshhshh, the Volunteer Auxiliary Thought Police don't have the strongest reading comprehension skills, so there is much that they miss.

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