The Boas-Chomsky Universality Theorem; Or, Cutting Molecular Anthropology Down to Size

Advances in genomics in the late-twentieth century inflated an expectations bubble. DNA was supposed to solve all medical problems before long and locate the real, molecular sources of human behavioral variability. DNA has been mobilized to answer Yali’s question — “Why is it that you white people developed so much cargo … but we black people had little cargo of our own?” If one wants to be strict about Mendelian genetics we can date it precisely at the turn of the century with the rediscovery of Mendel’s work in 1900. But appealing to biological reductionism to answer Yali’s question goes back to at least the early nineteenth century. (More on that soon.)

The most refined, if somewhat esoteric, recent attempt may be found in Gregory Clark’s A Farewell to Alms. Clark posits that the reason why the Industrial Revolution began in England (not true) was because the upper classes, who had more industrious, patient, disciplined, ie more bourgeois, genotypes, were more fecund than the lower classes (with their inferior genotypes). He literally has equations to track the slow regression to the mean of all the world’s upper class genotypes and tries to show that such sustained differential fecundity or differential survival of types did not happen elsewhere until much later. He never bothers to motivate the extremely polarized initial conditions — the Normans had to have been extraordinarily superior genotypes relative to the Anglo-Saxons (the Angles and the Saxons, or whatever you want to call the biological populations of England at the time) at the time of the Conquest in 1066 if a thousand years of regression to the mean has not eliminated their naturally higher rates of getting into Oxbridge and leaving large estates. In other words, Clark is the most refined neoracialist of the day: ‘the natural hierarchy of the races’ is posited as the controlling initial condition, since the rest follows from differential fecundity and survival.


An even more sophisticated sleight of hand may be found in the work of Galor and Maov; published, astonishingly enough, in American Economic Review. Here, ‘the natural hierarchy of the races’ is folded into the second moment — what explains global polarization is a quadratic or hump-shaped relationship between ethnogenetic diversity and economic potential. Societies with too much diversity are often dysfunctional; societies with too little genetic variability often fail to produce real breakthroughs except once in a blue moon; in the Goldilocks zone of genetic diversity we find the most advanced societies, the most innovation and all the other goodies economists love. There may be some truth to the matter. Ethnic diversity may indeed condition societal paths. But whether this is the controlling variable is hard to decide. Are high latitudes already privileged over low latitudes (with their high tropical diversity) and their Goldilocks diversity compounds or adds to their privilege, or does diversity trump latitude? They have established the former by showing that the partial correlation coefficients are significant after controlling for latitude (and a slew of other conditioners). They can hardly be expected to establish the latter for latitude itself controls diversity, and exceptions working against the grain of the Heliocentric geometry of our life world are few and far between.

The question of whether mere code is a good place to place causal vectors in human evolutionary biology is rarely posed. To be sure, we can explain certain patterns in physical characters and archeological assemblages etc by mobilizing population history (eg, depigmentation in northern Indians reflects their northern origin, as does the fact that they speak Indo-European). And molecular anthropology has a fine-scale resolution on population history. But even population history merely moves the explanandum to the initial conditions; we need to explain the initial conditions themselves by appealing to deeper principles (respectively, Gloger’s rule is why northern Indians are relatively more depigmented than southern Indians; Indo-Europeans descend from a people whose ethnogenesis was triggered by the introduction of advanced Sumerian technology in the steppe c. 5ka).

Genetics may prove useless to solve disease or explain phenotypic variation but molecular anthropology can certainly do phylogenetics. It is so good that other physical anthropologists test the phylogenetic signal of traditional trackers (craniometric and craniodental metrics, nonmetric cranial and dental polymorphism frequencies, slower-moving postcranial variables and so on) against molecular evidence; as indeed I have been doing without explanation.

But the fact that we have fine-scale or high-dimensional data does not land the causal structure of the world in our lap. It is the explanandum; not the explanation. More generally, DNA, brain scan and surveillance data, what we have is the curse of high-dimensional, fine-scale data that one can interrogate with machine learning algorithms. But Google can never predict whether I will have soup or salad with my lunch tomorrow; at the very least Google is forbidden from telling me the prediction (say soup) for then I can say, screw you Google, today I will have salad just to fuck with you. Not just ego but every awake human is capable of doing the exact same thing to Google. (We should make Google tell people its everyday predictions to screw with their predictive algos!)

To say that something is under genetic control, as I said about pelvic bone width and femur head diameter, is merely to place the explanandum at a specific level of analysis; in the realm of evolutionary biology and really slow-moving climatic and social transformations. In other words, it is just a genetic representation of systematic phenotypic variability that can then be explained though logics of bottlenecks, founder effects, population history, and selection. Put another way, Mary’s genes may explain her wide hips, but the fact that Europeans populations have wider hips requires explanation at a different level of analysis. A satisfactory explanation would reduce the specific explanandum of European pelvic bone widths to the general logic of body size for (say) our genus, order or kingdom.

So we can say that there has been strong selection in the genus Homo for bigger bodies and bigger brains constrained by recoverable secondary productivity, fertility rates, packing thresholds, and labor productivity. Put bluntly, hominins could afford their more energetically expensive bodies for any length of time only when sufficient protein was recoverable from the environment given the state of knowhow/level of foraging productivity, fertility rates and packing thresholds did not bind in the Malthusian sense, epidemiological burdens were light enough to allow high net nutritional standards, and natural selection continued to favor bigger bodies. We know that bigger bodies are still under selection for any reduction in health insults in any human population results in bigger bodies. This implies that the explanation of the Early modern collapse in body size in 1450-1650 must be sought in sharply reduced living standards (ie lower net nutritional status) that may themselves be  explained by say climate stress, epidemiology, war and societal instability.

Whatever the cause of the reduction, the reference frame we are working with allows us to establish the fact of an Early modern catastrophe that can be read off European phenotypes (and maybe genotypes some day). That this fact could be read off the genetic code is not explained by Mendelian laws. The notion that it is so is based on a misunderstanding of the role of the Mendelian component of the tripartite modern evolutionary synthesis. (The other components are natural history and natural selection.)

So, we may take the evidence we have marshalled as proof against the refined neoracialism of Gregory Clark. He has established that the upper classes were taller, bigger, and more fecund than the lower classes in England in the centuries after the Conquest. But the inference that English and European genotypes converged over time to the upper class genotype through this process is not borne out by European phenotypes which deteriorated sharply in the crucial phase at issue, 1450-1700 CE. For if he was right, we should expect the opposite movement in the slowest moving variables from what we see: European pelvic bone width should increase after the Medieval period.


Boasian antiracists know that there is a short step from worship of genes to worship of race. But they have failed to articulate the precise problem with biological reductionism. The problem lies in conflating levels of analysis. What looks like an explanation at the level of the individual or cohort, is the explanandum at the level of populations over many generations. To wit, DNA is just code. To say that vertical or global polarization (ie the differential economic performance of populations) is due to genetic differences — ie racialism as a scientific hypothesis — is at best like saying that rich Americans face lower tax burdens than their secretaries because of specific articles in the tax code. It is simply the wrong level of analysis — for a more satisfactory explanation of differential tax burdens we need an account of American political economy. Likewise, even if it can be shown that something is under genetic control, we still need an account of why the genetic code says what it does. And that takes us straight back across the Nature-Society dichotomy.

I owe a better, more general, explanation of the level of analysis problem to J. Dmitri Gallow. Think of a pole in a field whose shadow lands on May 14 on every year at a specific position where a stone has been in place since the pole was erected. A reductionist explanation would be: Here are the laws of optics, here’s the height of the pole and the distance to the stone, here’s the position of the sun that time of the year. One can seemingly hardly argue with the reductionist account. But wait. What if I told you that the pole was erected by Mr. Dawson because his wife came to grief precisely where the stone now sits on May 14, 1947, and that Dawson erected the pole to do precisely what it does every year on that sad day (in obedience to the laws of optics) precisely to commemorate the day she came to grief? That changes everything. The reductionist account turns out to be actively misleading in discerning the chain of causation for it turns out that human agency was the cause of the fact we were seeking to explain; that the nuts and gears of the reductionist account were involved in merely passive proximate processes.

A more fundamental critique of racialism and the self-congratulation of molecular anthropology must begin with the fundamental insights of Boas and Chomsky. The key observation is that the language faculty is exclusive to our species and uniform across it. To wit, a Japanese child growing up in Bengal would speak Bengali like a native. That can only be if the capacity for generative grammar (ie the capacity to generate a countable infinity of structured sentences from a finite lexicon) is truly universal across our species — and by implication under the tightest genetic control. The import is intellectually and politically radical: The Boasian universal — all hunter-gatherers were found without a single exception to have music, dancing, gossip, mythology, ritual, foraging expertise, and the full package of the drama of human life — trumps whatever minor systematic differences exist between populations. Put bluntly, not only the Romans and not only us moderns, but all societies of fully modern humans (ie endowed with the Boasian universal), whether they had high civilization or not, can identify with Greek drama. For even if we admit genetic disadvantages as handicaps, it may be retorted that even a severely handicapped person may turn out to make extraordinary contributions to the human project — think of Stephen Hawking. The human universal thus furnishes a powerful weapon against biological reductionism and the politics of biological differences.

We gotta cut molecular anthropology down to size. If only to get a better handle on physical anthropology, and ultimately, to make progress in answering Yali’s question.








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