A study on the origin of Covid-19 provided new evidence on Thursday supporting the theory that humans first caught the virus from infected animals at a Chinese market in late 2019. Nearly five years after Covid first emerged, the international community has not been able to determine with certainty exactly where the virus came from. The first cases were detected in the Chinese city of Wuhan in late 2019, but there have been bitter disputes between proponents of the two main theories. One is that the virus leaked from a Wuhan lab which studied related viruses, while the other is that people cau…