Why We Shouldn’t Be Concerned About COVID Spreading From Animals to Humans The physiological singularity of humans makes it possible for us to colonize the entire planet. Thousands of years ago, our ancestors left the African savanna and began migrating throughout the world, eventually settling down and establishing homes in nearly every part of the world, no matter how hot or cold the climate is, how high or low the altitude.
Why We Shouldn’t Be Concerned About COVID Spreading From Animals to Humans
This proclivity for dispersal and exploration prompted some to think of hominins — humans and our closest extinct cousins such as the Neanderthals — as the source of this inclination. — as the colonising ape. Our unusual biological and behavioural adaptability — sometimes called plasticity — allows us to adjust to a variety of inhospitable environments.
An analogous situation appears to be unfolding in the case of SARS-CoV-2 (the virus that causes COVID), which is now present almost anywhere people congregate these days. Moreover, it is possibly the same feature — flexibility — that has allowed for the fast expansion and evolutionary success of both humans and disease throughout history. In the same way that we are descendants of the early colonizing ape, the virus types that infect us are descended from the colonising virus. The fact that variations have evolved in other animals does not necessarily imply that they will constitute a significant hazard to humans.
Consider how people have adapted to adverse settings over the course of millennia to have a better understanding of why. Despite the fact that we are all members of the same species — Homo sapiens — there is a great deal of difference in our physical appearance and, to a lesser extent, in our genetic composition. Observations made by naturalists in the nineteenth century, for example, revealed that the average body size of warm-blooded species increases as the average temperature falls. Modern-day studies have proven that this pattern — known as Bergmann’s rule — holds true for some human populations, according to their findings.
Some other modifications can be observed in people who have lived in high-altitude places for a long enough period of time — such as some areas of Tibet — for which nature has selected features that are advantageous for survival in this environment. The air is dense in these areas, and as a result, there is less oxygen available for respiration. And, unlike in low-temperature conditions, people cannot simply put on thicker layers to improve their chances of survival; rather, they must undergo biological modifications. Researchers have now discovered specific genes that may be responsible for these physiological improvements, including increased oxygen delivery to the bloodstream and enhanced metabolism.
As a result, it is apparent that humans, like all other animals, have adapted to their environments over time. In contrast to other species, however, we did not evolve into new species in order to do so, and our adaptability contributes to understanding why. According to the evidence, we are specialists in a wide range of fields. Because of our ability to learn and our unique physiologies, we have the ability to adapt to almost every environment on the planet. The majority of species, on the other hand, are specialists. They have completely adapted to the unique ecological conditions in which they live. Artificially relocating any would almost certainly result in their extinction.
Generalist virus
Analogously, since it began transmitting among people, new SARS-CoV-2 variants appeared that helped the virus to infect humans more effectively. In its earliest detected state, the novel coronavirus infected different animals. We’ve known since mid-2020, for example, that cats and dogs are susceptible to infection, as are bats, which — directly or indirectly — people blame for the virus’s ability to infect humans. Yet it’s possible that what we’ve been dealing with all along is a virus that, because of its unusual evolutionary lineage, was, like us, a generalist.
The conditions of the Wuhan live animal and seafood markets in 2019 may have given SARS-CoV-2 the breeding ground to develop this strategy. Millions of creatures living in enclosed spaces on top of one another provide the perfect conditions for a virus — which overall evolve at astonishingly fast rates — to adapt to these hosts, without ever needing to develop strategies specific to any single one.
The variants we’ve consequently seen emerge among humans — alpha, beta, delta and now omicron — are the same evolutionary steps we’d expect from a novel organism adapting to a new host environment. Regardless of their other qualities, these variants are each more infectious and transmissible than the last. The virus is specialising to us, much as humans have specialised to the many environments we inhabit.
In 2020, a SARS-CoV-2 variant emerged in mink, which marked a step towards specialisation in that species. However, it didn’t pose much of a public health threat to humans. More recently, there has been evidence of zoonosis from Ontario deer – and there are likely to be many more such examples in the future – but these variants are unlikely to outcompete better human-adapted variants such as omicron. Much as people that evolved to live in particular environments, or to have a particular kind of diet, face health threats when their living circumstances drastically change, SARS-CoV-2 variants that evolve in other species won’t be specialised to us.
Omicron, and whatever the next variants are that signify increased specialisation to humans, are likely to be better adapted, and thus fitter when circulating among us. Claims about the threats of animal reservoirs are, therefore, probably unfounded. But we should, of course, continue to be vigilant. Why We Shouldn’t Be Concerned About COVID Spreading From Animals to Humans
As we enter the third year of the pandemic, it’s critical, perhaps more than ever, that we use the intelligence with which evolution has graced us — and which has been, and continues to be, essential to our survival — to outmanoeuvre the public health threats we face. More and better-specialised variants of SARS-CoV-2 will continue to emerge. And it’s towards these — and novel viral threats that stem from dangerous agricultural practices — that we should look.
Jonathan R Goodman, PhD Candidate, Human Evolutionary Studies, University of Cambridge
This article is republished from The Conversation under a Creative Commons license. Read the original article.