General public knowledge seems to accept the earliest explanation for the emergence of the novel coronavirus, that it jumped from animals to humans in a live animal "wet" market in Wuhan in December 2019, and there unfortunately mutated to become especially good at human-to-human transfer. The ultimate source of the virus under this theory is assumed to be either bats or pangolins, both of which regularly carry coronaviruses similar to the one that causes Covid-19. However, scientists have been exploring a potential cluster of cases in China in November, unrelated to the animal market, and a new article in Nature Medicine suggests that the jump may have happened even earlier. Important genetic mutations that have made this virus especially dangerous have not yet been found in either bats or pangolins, suggesting that it may have jumped to humans earlier in a different (less virulent) form, and then mutated into its current deadly form entirely within the human population. Although this might seem academic, since either way, it's still a zoonotic virus that jumped from animals to humans, it's actually quite important. If the virus jumped earlier, and the mutations that made it especially dangerous only happened after the jump, then defeating the virus might actually be possible, since there is less worry that it could "re-jump," so to speak, from animals again. It's extremely unlikely that a second jump from animals to humans of the same ancestral virus would result in the same mutations that made this strain so bad. If, however, it suffered these mutations before jumping to humans, then there is the risk that this deadly virus is still endemic in animal populations, and could re-infect humans at any time.