The coronavirus that's ravaged the world in the past 18 months isn't the first to emerge from Asia and cause widespread illness.

There's evidence one "similar to COVID-19" tore through eastern Asia 20,000 years ago, according to a new study. 

"The modern human genome contains evolutionary information tracing back tens of thousands of years, like studying the rings of a tree gives us insight into the conditions it experienced as it grew," said Kirill Alexandrov of the University of Queensland.

An international team of researchers from the US and Australia synthesised proteins from both humans and the SARS-CoV-2 virus, which causes COVID-19, and analysed how they interacted. 

"Computational scientists on the team applied evolutionary analysis to the human genomic dataset to discover evidence that the ancestors of East Asian people experienced an epidemic of a coronavirus-induced disease similar to COVID-19," said Prof Alexandrov.

Evidence of the ancient pandemic was found in the genomes of people from China, Japan, Mongolia, North Korea, South Korea and Taiwan.

"In the course of the epidemic, selection favoured variants of pathogenesis-related human genes with adaptive changes presumably leading to a less severe disease."

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Some scientists have said eventually the same will happen to COVID-19 - it will weaken, its chances of surviving a long time going up if it's not so lethal.

"By developing greater insights into the ancient viral foes, we gain understanding of how genomes of different human populations adapted to the viruses that have been recently recognised as a significant driver of human evolution," said Prof Alexandrov.

"Another important offshoot of this research is the ability to identify viruses that have caused epidemic in the distant past and may do so in the future. This, in principle, enables us to compile a list of potentially dangerous viruses and then develop diagnostics, vaccines and drugs for the event of their return."

There are seven different coronavirus known to infect humans - in addition to SARS-CoV-2, two others are known to cause severe illness - the original SARS virus and MERS. 

The four others produce mild illness, and are categorised as the common cold. 

While the exact origin of SARS-CoV-2 is still being investigated, it's widely believed to have originated in bats in China. 

The new research was published in journal Cell Press.