Humans are creating conditions that make coronaviruses and other pathogenic diseases more common and more virulent. It turns out that the proliferation of novel coronaviruses is just one more devastating consequence of the industrial decimation of the natural world.
Like all life* forms, coronaviruses constantly evolve. In fact, they mutate with shocking speed, far faster than cellular life forms. Two mechanisms of that evolution create potentially lethal new variants. The first is point mutations, the change in one single nucleotide base. These small changes are often not significant, and coronaviruses do not readily mutate. But millions of human infections by billions of viral particles produces vast opportunities for potentially consequential changes.
A second evolutionary mechanism produces more profound changes to viral species. Homologous recombination is the novel combination of genetic material from two similar, “parent” strains of a virus. It is more fundamental change on a larger scale. Novel pathogenic coronaviruses – such as SARS-CoV and probably SARS-CoV-2 (the name of the virus responsible for Covid-19) – arose from the homologous recombination of two viruses co-infecting a single cell. So did HIV and classical swine fever virus.
“coronaviruses frequently undergo homologous recombination when they co-infect a host, and that SARS-CoV-2 is highly infectious to humans, the most immediate threat to public health is recombination of other coronaviruses with SARS-CoV-2. Such recombination could readily produce further novel viruses with both the infectivity of SARS-CoV-2 and additional pathogenicity or viral tropism from elsewhere in the Coronaviridae.”
One candidate to vector the next coronavirus to humans is the Asian Palm Civet (Paradoxurus hermaphroditus). According to the new model for calculating the likelihood of novel coronaviruses, the Palm Civet is “a potential host of 32…different coronaviruses (in addition to SARS-CoV-2).” Genetic analysis has already demonstrated that SARS-CoV-2 is closely related to coronaviruses derived from the Palm Civet. But... it is not the Palm Civet...that poses the threat. It is the way humans interact with the Palm Civet. It is our horribly destructive relationship with wild animals that makes the Palm Civet a likely disease vector more than any part of Civet biology. The problem is us, not them.
Palm Civets are hunted for bushmeat and, despite being wild, solitary and nocturnal animals, kept as pets. One investigation found Palm Civets widely available in wildlife markets throughout Indonesia. Most of the Civets for sale were young and in poor health, suggesting they were captured in the wild.
Kopi Luwak is brewed from coffee cherries that have been consumed and partially digested by civets. Civets are now housed in battery cages—rows and columns of identical cages stacked upon each other—and force-fed coffee cherries. Factory farming—a nightmare for breeding infectious disease—has come for the Palm Civet. The proximity of cages, stress of conditions, and bacterial infections combine to make civet farms likely hot spots for the outbreak of pathogenic diseases.
Palm Civets are not the only potential vector species. Other species also house several coronaviruses and are thus likely sites for coronavirus recombination to occur. Signaled out by the researcher’s model are the lesser Asiatic yellow bat (Scotophilus kuhlii) already a known coronavirus carrier, as well as the greater horseshoe bat (Rhinolophus ferrumequinum)—predicted to host 68 different coronaviruses. The common hedgehog (Erinaceus europaeus), the European rabbit (Oryctolagus cuniculus) and the domestic cat (Felis catus) are also seen as likely hosts for SARS-CoV-2 and large numbers of other coronaviruses. Worryingly, the research also found that the common pig—"the most prominent result for a SARS-CoV-2 recombination” is a likely vector.
Deforestation and habitat destruction not only bring humans into greater contact with wild animals and any diseases they may carry, but also makes pandemics more likely.
Research demonstrates that this happens because as humans destroy habitats, species go extinct, reducing biodiversity. Those species that survive and even thrive in such situations—think rats and bats (and some bird species)—are more likely to host the dangerous pathogens that might jump to humans.
I remember learning about dumb things people used to do in the past. My parents would say, "They didn't know any better, honey."
But when smart people do dumb things and ignore the consequences...