On Friday, 22 scientists from Chinese universities and research institutions published a commentary supporting the natural origin of SARS-CoV-2 on the journal Science China Life Sciences, citing evidence from evolution theory and lack of proof of artificial tempering in the virus's genome.
The article came after 24 scientists from around the world published an open letter in The Lancet medical journal this month, stating that the virus most likely originated in nature and not in a lab.
Wu Chung-I, the corresponding author of the article and a biology professor at Sun Yat-sen University in Guangzhou, Guangdong province, told China Daily that SARS-CoV-2 is extremely well adapted to the human population compared to SARS-CoV in 2003.
This level of adaptiveness has most likely evolved over a long evolutionary time span as the virus accumulates a series of slight improvements through random mutations. "In this view, SARS-CoV-2 could not have possibly evolved in an animal market in a big city and even less likely in a laboratory," he said.
Wu said the claim of non-natural origin of SARS-CoV-2 is moot "because recent evidence from mutational signature shows that the virus's evolution follows natural law to the dot". Those who argue the virus is man-made should find signatures that defy natural laws, such as barcoding commonly used in tracing cell lineages. Otherwise, "it would be more productive to focus on the natural processes to the SARS-CoV-2 origin," he said.
Wu said prior to the COVID-19 outbreak, the virus may have undergone some forms of multi-step evolution in human populations, resulting in its extraordinary adaptiveness. But how exactly this progress has occurred remains a mystery.