DNA is Mere Code

What is biology as ideology, pace Lewontin? The central theorem of racialism was that ‘the natural hierarchy of the races’ explained world order. Neoracialism in its modern guise as biological reductionism affects a double reduction: World order (say, the economic performance of nations, races and classes) is explained by phenotype (say, IQ or the capacity for disciplined work) that is in turn explained by genotype. The causal structure of racialism is simple: genotype → phenotype → world order.

The Human Genome is mere code. More precisely, genes are fragments of code whose frequencies get shuffled every generation. At the level of the individuals, genes can be said to control a character. But that does not mean anything at the level of populations. In population genetics, genes encode the very information that needs to be explained by evolutionary biology. Even if a character can be said to be under tight genetic control, that’s just the explanandum. The genes are merely records of decisions arrived at a completely different level.

Natural selection acts directly on phenotypes and only indirectly on genotypes. For instance, depigmentation came under natural selection in paleo-demes situated above 46ºN. In different northern populations, depigmentation was achieved on a different genetic basis. So Gloger’s rule is fulfilled with whatever genetic representation comes in handy. Similarly for Bergmann’s and Allen’s rules and craniofacial and craniometric characters. The causal vector where it counts, at the level of situated breeding populations, is rather: phenotype → genotype.

ET

In fact, the causal logic of neoracialism is best turned on its head: world order → phenotype → genotype. We have already argued above that phenotype controls genotype. It is also the case that world order sensu lato controls phenotype. So, for instance, just as Western stature (more reliably, thigh bone length) began to rise with the hockey-stick at the turn of the century, the stature/thigh bone length/living standard of Black South Africans was collapsing. See next figure. This is of course because the global color line fell precisely on them at the turn of the century. More generally, the whole struggle between Anglo-Saxon visions of the colorblind empire and high racialism came to a head on the South Africa Question. Black South Africans were the frontline in more ways than one.

CollapseLatour.png

Turning the causal logic of racialism on its head is particularly potent because it inverts the reductionist arrow of causality across the fundamental Nature-Society dichotomy of Western thought identified by Latour. The reductionist insists that the causal vector points in only one direction: Nature → Society. Try to square that with the following fact uncovered by Diane Lauderdale at Chicago: Arabic-named women who gave birth in California in the six months following 11 September 2001 experienced an increased risk of low birth weight and preterm birth compared with similar women who gave birth a year earlier. ‘The finding that Arabic-named women who were pregnant in September 2001 had an increased risk of poor birth outcomes,’ Lauderdale notes, ‘is consistent with the hypothesis that ethnicity-related stress or discrimination during pregnancy increases the risk of preterm birth or low birth weight’. That makes mince-meat out of biological reductionism.

rsos161054f03_height_protein

Importantly, the inverted causal logic, world order → phenotype →  genotype, clears up the whole confusion about anthropometric measures of living standards. Do body size variables (stature, body mass, femur length, femur head diameter, pelvic bone width) capture living standards or natural selection? The answer is clear in the case of plastic variables like stature/femur length. To say that pelvic bone width is under genetic control is merely to observe that it is a slow-moving parameter of the human skeleton. It does not explain diachronic and synchronic variability (ie systematic time-variation and cross-sectional variation) in this character.

When a parameter is under tight genetic control, in order to comprehend the logic of systematic variation, we must zoom out in the temporal dimension and recall that any sustained reduction in health insults in any human population reliably results in increasing body size. Then the confounding vanishes; the tension resolves. Put another way, every variable is plastic on a long enough time horizon and slower-moving body size variables encode information on long-term fluctuations in living standards. In other words, we can indeed interpret the collapse of European pelvic bone width in the early modern period as a representation of a multi-generational collapse in living standards.

Biiliac

The proximate causal vector of racialism, phenotype → world order, has been inverted by Boasian antiracists since Boas himself. We must also invert the causal vector of biological reductionism proper, genotype → phenotype. We must fully comprehend that DNA is mere code. The placement of any causal vectors at all on this bit of code is profoundly mistaken.

The reductionist paradigm can be defeated in detail. Take Tuberculosis. The reductionist logic that a bacillum causes TB is true at the level of the individual. But it nonsensical at the level of populations. Systematic variation in TB incidence is driven not be epidemiology but by economics. Poor nations have higher rates than rich nations. India does not have a high rate of TB because of a higher population of the bacillum — to the contrary, the higher population of the damn bacillum is the result of Indian poverty.

Tb.png

Or take the famous Bantu “racial character” — sickle cell anemia that was tied to resistance against malaria. Even if there were such things as racial characters, it is decidedly not one. First of all it is shared by non-Bantu populations in southern Europe, the gulf region, north Africa, Madagascar and India. Moreover, comparing the maps for malaria endemicity and the allele frequency, it is clear that many populations where malaria is endemic do not have the allele. Whatever is keeping this polymorphism under selection is not simply the global distribution of Anopheles mosquitoes. Put another way, the natural history of mosquitoes themselves contains information on the lives and struggles of human populations past and present; information that can potentially be read off the genomes of both.

SickleCell

A whole lot of confusions and misunderstandings are cleared up once we get explicit about the levels of analysis and see DNA for what it is. Mere code.

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