The above map shows cumulative coronavirus cases. One of the things that I’m still confused by are some geographic patterns. For example, Thailand with 70 million people has had fewer than 4,000 cases and 60 deaths attributed to COVID-19. Bolivia with 11 million people has had 8,900 deaths. Why? There are many theories out there. One thing that is hard to deny: mainland Southeast Asia and Northeast Asia seem to be handling the pandemic “well” (at least after the Wuhan outbreak).
A new preprint on bioRxiv has gotten people even more curious, An ancient coronavirus-like epidemic drove adaptation in East Asians from 25,000 to 5,000 years ago:
The current SARS-CoV-2 pandemic has emphasized the vulnerability of human populations to novel viral pressures, despite the vast array of epidemiological and biomedical tools now available. Notably, modern human genomes contain evolutionary information tracing back tens of thousands of years, which may help identify the viruses that have impacted our ancestors – pointing to which viruses have future pandemic potential. Here, we apply evolutionary analyses to human genomic datasets to recover selection events involving tens of human genes that interact with coronaviruses, including SARS-CoV-2, that started 25,000 years ago. These adaptive events were limited to ancestral East Asian populations, the geographical origin of several modern coronavirus epidemics. An arms race with an ancient corona-like virus may thus have taken place in ancestral East Asian populations. By learning more about our ancient viral foes, our study highlights the promise of evolutionary information to combat the pandemics of the future.
The evidence in the preprint is pretty persuasive. First, I need to communicate something the last author told me: there is no evidence in their results that East Asians have particular robustness or vulnerability to COVID-19. That is due to the fact that these selection sweeps can cut both ways with this particular virus. The GWAS themselves need to be done, and they haven’t been (something like the GWAS done in Europeans).
But, if you eliminate this possibility that makes us ask, why are diverse East Asian societies doing relatively well? Thailand is not Confucian. Vietnam is somewhat, and South Korea is a great deal. But all these nations have been doing well (Confucian South Korea actually has about 10 times more per capita deaths than Thailand).
Second, what was going on 25,000 years ago? One of the things I learned in a book like Fate of Rome is that pandemics are a feature of civilized dense global empires. So it seems unlikely that the ancient proto-Asians were subject to pandemics. But I have read that even endemic infectious diseases may have had issues at hunter-gather population densities. But the results from this preprint indicate a massive sweep for many generations right before the Last Glacial Maximum. Figure 1 in the preprint makes it obvious that this is restricted to East Asians. That being said, the signal in Japanese seems a bit attenuated compared to the Kinh and groups from China, so I wonder if this did not impact to the Jomon (25% or so of Japanese ancestry) but was restricted to somewhere in mainland East Asia?