A VINDICATION OF EVOLUTION IN THESE TIMES OF CORONAVIRUS
Jorge V. Crisci
It is a curious paradox that the President of the United States, Donald Trump, has appointed his Vice President, Mike Pence, to lead the federal government’s response to the novel coronavirus (SARS-CoV-2, that causes the disease COVID-19). The new virus is the result of evolution and Mr. Pence denies that there’s such a thing as evolution while championing creationism. He thus faces not only a serious outbreak, but another solid proof that evolution is true. Viruses evolve, as do organisms formed by cells (bacteria, animals, plants and fungi), basically meaning relatedness by descent with modification, mutation and /or recombination that generate variation, and natural selection acting on that variation These same processes also explains why new strains of the influenza virus appear every year, and the emergence of antiviral drugs resistance by strains of HIV that causes AIDS. Mainly two processes played a role in the appearing of the new coronavirus: mutation and natural selection. We can assume that, at the beginning, the viruses in the animal (bats) lacked the ability to infect humans. Over time, variants of those viruses may appear that, by changes in their genes (mutations), acquire that capacity and find the opportunity to infect a human, probably through an intermediary animal. In that environment (the human body) natural selection will benefit these viruses better adapted to infect and survive in people and, therefore, will be able to leave offspring in the next generation unlike those who are only able to infect the animal. On the other hand, the adapted ones acquire (probably by another mutation) the ability to transmit between people. It cannot be completely ruled out, that a recombination (viruses swapping chunks of genetic material) of the bat virus with a virus of the intermediary animal had also led to a strain that could survive within the human body. Nevertheless, whatever the source of the new variants, natural selection ensured that the virus that emerged had a suite of traits that made a pandemic almost inevitable. Mutations (and/or recombination), leading to the opportunity to infect humans and the ability of person-to-person transmission, are random events, which could lead us to think of a very low probability that all three events could occur almost simultaneously. However, two facts increase that probability. (l) The virus demographic factor: viruses have a large population size and produce a large number of generations (with potential random changes in genes) in relatively short times. (2) The human factor: a synergy of elements catalyzed by inadequate sanitary conditions; consumption and handling of potentially dangerous foods, such as sick animals; easy access of people to contaminated food, dense populations around the first detected cases; and insufficient scientific knowledge in the early stages of infection. Natural selection operates on the products of chance, but in that operation, chance does not intervene, but rather rigorous and complex biological factors, to which the only correctable factor, the human factor, is added in the case of the new coronavirus. As would be anticipated, genomic data collected by scientists since the beginning of the outbreak, show that this virus is randomly mutating as the pandemic rages around the world. These mutations are useful markers of transmission, since closely related genomes indicate closely related infections. By reconstructing an evolutionary genealogy of these different genomes, scientists are learning about spatial spread, introduction timings and epidemic growth rate. It is unlikely (though not impossible) that some of these new mutations could make the virus more harmful but, doubtless, they are another vivid –and painful– confirmation of evolution.
