[Reporter] Bioethicists Kerry Bowman once visited the now-infamous seafood market in Wuhan, China.

It was packed full of live and dead animals.

A leading theory is that a worker inside this market contracted the virus from an animal.

[Bowman] You've got urine and feces spraying from one enclosure to another

creating really an incubator for emerging viruses.

[Reporter] Now, a newly published paper strongly suggests, like SARS

the original source of this virus was bats.

Scientists sequenced its genome

then compared it to other coronaviruses living inside horseshoe bats from eastern China.

They found a close match.

Slightly different from SARS but in the same family.

[Man] Most of it will come back to bats.

[Reporter] Professor Scott Weese studies and treats infectious diseases in animals.

He says bats live all over the world.

They're essential in pollinating fruit and eating insects.

And they've been passing diseases to one another in their vast colonies for thousands of years.

But Weese says they also have an important trait in common with us.

Bats are mammals so they are related to us.

And if certain components of that bat are somewhat human-like

it makes that ability to virus across a lot easier.

[Reporter] Meaning a virus that likes living in a bat may also like living in us.

The question is why don't the viruses sicken or kill the bats?

They're the only truly flying mammal and that's got to have some impact on its physiology

[Reporter] Peter Daszak studied bats in China for 15 years.

He speculates that as bats evolved to fly somehow their immune systems changed.

If we could find out you know the chemicals that bats use within the body to regulate viruses

maybe some of those could be used as potential drugs against some of those viruses.

[Reporter] Flying also gave bats the ability to easily spread disease.

Their bites urine and feces can infect people and animals on farms

and in the wild.

The market that I saw in Wuhan, we counted 56 different species.

So a lot of these species and probably almost two-thirds of them were wild.

[Reporter] Stopping the sale of wildlife in these markets would help

but people are also encroaching on the areas where bats live.

Scientists say we need to do a better job studying and monitoring bats.

More outbreaks like this one are inevitable

but lessons can be learned from this virus

with the goal of getting ahead of the next one.

Christine Birak, CBC News, Toronto