BEIJING, July 23 (Xinhua) -- The claim that the SARS-CoV-2, the virus that causes COVID-19, is made by humans is a terrible regression of scientific thinking, said a leading Chinese evolutionary biologist.
Professor Wu Chung-I with the School of Life Sciences at Sun Yat-sen University said in a recent interview with the China Science Daily that Chinese scientists have proposed a series of models to trace the origin of COVID-19. He hopes that his international counterparts could find a way to the truth by an objective discussion with a scientific attitude.
Wu and 21 other scientists working with universities and hospitals in China, or with institutions affiliated to the Chinese Academy of Sciences, published an article titled "On the origin of SARS-CoV-2 -- The blind watchmaker argument" on July 16 in the latest issue of the journal Science China: Life Sciences.
"The article discusses the origin of SARS-CoV-2 in two ways. First, why can nature evolve such a virus? Second, why can't humans create such a virus?" said Wu.
He mentioned the classic argument of the blind watchmaker in the history of science.
"As we can see, all kinds of creatures in nature are perfectly adapted to their living environment," he said.
In 1794, William Paley, a British priest, argued that this complex and perfect adaptability of natural creatures is like a delicate clock. He said it is impossible for people to imagine such adaptability comes from nature, and there must be a watchmaker, or a god, who designed and made it.
About 200 years later, famous evolutionary biologist Richard Dawkins refuted Paley's argument in his popular book "Blind Watchmaker."
"Dawkins emphasized that natural species evolve without special purpose. If nature is a watchmaker, it could only be a blind one. A species that perfectly adapts to its environment is not created all at once but is the culmination of a series of small improvements from a large number of random mutations over a long period of time.
"When some people claim the novel coronavirus is human-made or leaked from a lab, one of their main ideas is that how could a virus such as novel coronavirus, which perfectly adapts to the human body, come from a blind and aimless nature?
"Such claim is a terrible regression of scientific thinking, a regression to the same level with a priest more than 200 years ago," said Wu.
"SARS-CoV-2, as the most 'perfect' virus so far in human history, has to be the product of natural selection," he added.
He said nobody, even the elite scientists, could know in advance how to create a virus that perfectly adapts to humans. He compared the process to mobile phone marketing -- even the most skilled electronic laboratory could not design the world's most popular mobile phone in one attempt.
"The perfect product must be based on market testing and repeated adjustments," he said.
"Therefore, we infer that the virus had gone through repeated mutual infections between wild animals and people before the first reported outbreak of COVID-19 and, gradually, accumulated mutations adapted to the human body.
"In the process of human infection, the virus experienced repeated defeat until it evolved into the current strains that are extremely suited to mass transmission," he added.
The evolution history of human coronaviruses relating to the common cold, such as types OC43, 229E and NL63, also proves this point. These coronaviruses have been infecting and spreading among humans and wild animals for hundreds of years before spreading globally.
"People are trying to find a strain in a wild animal that is very similar to SARS-CoV-2. Given the current extent of SARS-CoV-2 infection, if such a wild animal could be found, it was most likely infected by humans, instead of the other way around," he said, adding that such efforts need guidance from scientific theories and models.
He mentioned that Chinese scientists are working on various models and hypotheses. His team published an article "A theoretical exploration of the origin and early evolution of a pandemic" in the journal Science Bulletin.
The article proposes an incremental evolution model of SARS-CoV-2, in which the virus is believed to have originated in a habitat of animal hosts, or PL0, sparsely populated by humans, and the frequent and long-term animal-human interaction allowed it to evolve.
Both the animal and human hosts develop a degree of herd immunity. Then the virus could occasionally spread to somewhere outside the habitat with a large human population that does not have herd immunity, resulting in the first outbreak.
Wu explained that the place of the first outbreak is different from PL0 because the human population in the place of the first outbreak does not have herd immunity. The flu pandemic in 1908 and the AIDS epidemic all prove the possibility of this model.
The human population in PL0 may have established herd immunity to novel coronavirus a long time ago, and the trace of such herd immunity is likely to be stored in T cells rather than in antibodies.
T cells are one of the primary types of lymphocytes that play a crucial role in the immune response.
"It is a great challenge for our current detection technology to find such traces, but I believe sooner or later, we can solve this technical problem.
"More importantly, even if somewhere is proved to be PL0, there is no so-called original sin in PL0. The origination of novel coronavirus is a natural disaster rather than a human-made disaster, and humans can only choose how to deal with the epidemic," said the biologist.
"The COVID-19 pandemic concerns the lives and health of all people and the global community. We hope the global community can return to scientific rationality on this issue as soon as possible, and face up to the challenge and seek the truth." Enditem