The origin of the novel coronavirus has been widely discussed online since the outbreak. The conspiracy theories around it have also emerged endlessly.
Previous scientific studies have already suggested that SARS-CoV-2, the virus that caused COVID-19, originated through natural processes.
In a recent interview with ABC news, Dr. Robert Garry, a professor at the Tulane University School of Medicine, once again pointed out that it's a misconception to believe the virus originated at a seafood market in Wuhan, China.
"Our analyses, and others too, point to an earlier origin than that," Garry said. "There were definitely cases there, but that wasn't the origin of the virus."
According to Garry, the pandemic may be triggered by the mutation in surface proteins of the virus. But it's also possible that a less severe version of the illness was circulating through the population for years, perhaps even decades, before escalating to this point.
Evidence for natural selection
Coronaviruses are named for the crown-like spikes on their surface. In a study published on Nature Medicine, a group of scientists including Dr. Robert Garry from the U.S. Britain, Australia analyzed two specific features of spike proteins of the virus, which are responsible for griping and entering into the host cells.
The results show that the SARS-CoV-2 spike protein is optimized for binding to a molecular on the outside of human cells, so efficient that scientists concluded it was the result of natural selection and not a purposefully manipulated virus.
Besides, if someone were trying to make a new virus, they have to engineer it from the backbone--molecular structure of a virus which is known to cause diseases in human, scientists said.
But what they found is that the SARS-CoV-2 backbone is not derived from any previously used virus backbone. The most closely resembled backbones were discovered in bats and pangolins.
"These two features of the virus, the mutations in the RBD portion of the spike protein and its distinct backbone, rules out laboratory manipulation as a potential origin for SARS-CoV-2," Kristian Andersen, an associate professor of immunology and microbiology at Scripps Research and corresponding author of the paper told Science Daily.
Two possible answers to the SARS-CoV-2 origin
What is exactly the natural origin blamed for COVID-19 has yet been worked out by global scientists. But they do propose two possible scenarios that can plausibly explain the origin of SARS-CoV-2, that is natural selection in an animal host before zoonotic transfer, and natural selection in humans following zoonotic transfer.
According to Dr. Francis Collins, the director of the U.S. National Institutes of Health, in the first scenario, as the new coronavirus evolved in its natural hosts, possibly bats or pangolins, its spike proteins mutated to bind to molecules similar in structure to the human protein, thereby enabling it to infect human cells. Both the SARS and MERS outbreak followed this way.
The second scenario is that the new coronavirus crossed from animals into humans before it became capable of causing human disease.
Then, as a result of natural evolution, the virus eventually gained the ability to spread human-to-human and cause diseases.
