When the research was posted on BioRxiv, it became apparent that there had been some confusion. It was not the entire pangolin virus, only something called the spike protein, that was nearly identical to the same part of the new coronavirus that infects humans.

Several research papers by Chinese scientists have questioned the likelihood of the virus spilling over from pangolins directly to humans, noting differences in the pangolin virus and the human virus.

The paper published Thursday in Nature examined a second set of Malayan pangolins seized from a smuggling operation and also found coronaviruses much like the ones previously studied. The authors concluded that pangolins should not be traded, because although there is no evidence these viruses jumped directly to humans, they have the potential to sicken people.

There are many, many coronaviruses in animals, most of which do not infect people, and although knowing how they get to humans won’t affect the course of the current pandemic, such knowledge will help for the future.

Dr. Andersen said there are several paths the new virus could have taken. Assuming that it began with a bat virus, it could have jumped directly to humans, although that didn’t happen in the other coronavirus outbreaks of SARS and MERS.

Or it could have passed from a bat to another animal, one of the many that humans hunt, raise for food and sell in markets. Dr. Andersen said that the virus didn’t necessarily first spill over to humans at the Wuhan market initially marked as the likely source of the outbreak. It could have happened elsewhere.

Dr. Daszak said that South China “has an abundance of mixed wildlife-livestock farms that house chickens, ducks, civets, porcupines, pigs, bamboo rats, altogether all in conditions that would be conducive to viral spillover and spread.”