29 Dec 2020 Ancient Migration Patterns Offer Explanation for Unequal Susceptibility to COVID-19
A group of genes passed down from human cousins who went extinct 50,000 years ago explains why inhabitants of certain regions of the world are far more susceptible to COVID-19 than people living elsewhere, according to new interdisciplinary research.
Two distinct phenomena—the migration of homo sapiens from east Africa to the north and east between 70,000 and 100,000 years ago and the spread of the novel coronavirus in the opposite direction over the past year—are connected, concludes Duke University scholar Adrian Bejan in his paper, “Coronavirus Invasion and Neanderthal Retreat.”
The Romanian-born professor of mechanical engineering correctly predicted as early as March that the pandemic would spread from east to west. At a time when medical professionals feared that sub-Saharan Africa, with its poverty and underdeveloped healthcare systems, would be particularly vulnerable to COVID-19, Bejan pointed out that sub-Saharan Africans’ lack of Neanderthal DNA would leave them largely unscathed.
An outbreak of a COVID-19 variant, known as 501.V2, in South Africa shortly before Christmas may actually confirm Bejan’s observation. Even though South Africa accounts for less than 5 percent of Africa’s population of 1.3 billion, the country has over 35 percent of the continent’s confirmed cases. The higher percentage of people of European or Indian/Asian descent along with those of mixed race in South Africa, about 20 percent of the population, as compared with other sub-Saharan African countries, translates into a higher percentage of people with Neanderthal DNA.
“The conflict between the easy explanation and the pattern in the data (chronology, geography, spreading) means only one thing, people on the globe are not uniformly susceptible to the coronavirus,” Bejan writes. “If not equally susceptible, then why?”
The key to understanding this development lies not in the virus itself, but in people’s genetically-determined susceptibility to it, Bejan explains. On their migration path from east Africa, homo sapiens had three interbreeding events with Neanderthals and other hominids who inhabited Europe, the Middle East, and Asia. “The percentage of Neanderthal DNA in humans increased stepwise through each interbreeding event, from zero in Sub-Saharan Africans to roughly 4 percent in East Asians,” Bejan says. Today, the maximum amount of Neanderthal DNA found in humans is 4 percent, and these are the people who are at greatest risk from COVID-19.
Today’s pandemic originated in China in late 2019 under conditions the government in Beijing has steadfastly refused to disclose. In China, the disease spread in all directions before moving east to Korea and Japan and then south to Thailand, Singapore, Australia, etc.
“Later,” he writes, “it spread to the west in this sequence: India, Iran, the Middle East, North Africa (Egypt), North America, and now most of Europe.” He doesn’t mention it, but the disease eventually infected people in South America, with densely populated urban areas in Argentina and Brazil particularly hard hit.
Following an Ancient Map
Jet travel enabled today’s coronavirus to travel rapidly, but it did so using an ancient map subconsciously followed by humans during their first encounters with Neanderthals.
Bejan draws three conclusions from his analysis of the data:
- The nonuniform distribution of human susceptibility to the coronavirus corresponds to the nonuniform distribution of Neanderthal DNA.
- The susceptibility to the coronavirus was inherited from the Neanderthals, which is why those with zero [Neanderthal] DNA are less susceptible to the disease.
- If the most susceptible to viruses were the Neanderthals, then it stands to reason that the Neanderthals declined to extinction because of virus-induced diseases, not because Darwinian competition with allegedly superior humans out of Africa.
The link between Neanderthal DNA and susceptibility to COVID-19 was confirmed in a separate study published in Nature in September. Researchers at the Max Planck Institute for Evolutionary Anthropology compared the genetic profiles of about 3,200 hospitalized COVID-19 patients and nearly 900,000 people from the general population. They found that a cluster of genes on chromosome 3 inherited from Neanderthals is linked to 60 percent higher odds of needing hospitalization.
People with COVID-19 who inherited this gene cluster are also more likely to need artificial breathing assistance, co-author Hugo Zeberg said in a news release. In South Asia, roughly 30% of people have them, compared with approximately one in six Europeans. The troublesome gene cluster is almost totally absent in Africa and East Asia. Summarizing their findings, the authors conclude, “with respect to the current pandemic, it is clear that the gene flow from Neanderthals has tragic consequences.”
In confronting a pandemic, the first thought is to look at the world of medicine to find a cure. And, sure enough, pharmaceutical giants Pfizer/BioNTech and Moderna produced vaccines within an astounding nine months that are already being distributed. But exploring the pandemic’s spread and human susceptibility leads the inquiring mind elsewhere—to the fields of anthropology, genetics, and even physics.
Bejan is the father of constructal thermodynamics, a theory that holds that “for a flow system to persist in time it must evolve in such a way that it provides easier access to its currents.” By applying the theory to the spread, or flow, first of homo sapiens and then of COVID-19—and showing that the two are interrelated—he has deepened our understanding of the challenge confronting us. After all, this will not be our last pandemic.