Studies show that the virus is closely related to one found in some species of bats.

BBC: Fifth coronavirus death reported

The structures of proteins with similar functions in distantly related species are so closely alike that they could not be the determinants of their different developments.

ECONOMIST: Genetic science

By studying more than 31, 000 bits of the genome and measuring how closely humans are related to chimpanzees in different places, the scientists were able to study how quickly the species became different from each other.

ECONOMIST: Humans could have interbred with chimpanzees