The origin of SARS-CoV-2, the virus causing COVID-19, has been the subject of extensive research. Analysis of the SARS-CoV-2 genome reveals features that suggest it evolved naturally rather than being created in a laboratory. Key features include an optimized receptor-binding domain (RBD) for binding to human ACE2 and a polybasic furin cleavage site in the spike protein, which may enhance viral infectivity. These features are not found in related betacoronaviruses, indicating natural selection in an animal host or in humans after zoonotic transfer. The RBD of SARS-CoV-2 is optimized for binding to human ACE2, suggesting natural selection in an animal host before zoonotic transfer. Bats are likely reservoir hosts, with RaTG13, a bat coronavirus, being closely related to SARS-CoV-2. However, its RBD does not bind efficiently to human ACE2, indicating further adaptation. Pangolins also show similarity to SARS-CoV-2, suggesting a possible intermediate host. The polybasic cleavage site and O-linked glycans in SARS-CoV-2 are not found in related betacoronaviruses, suggesting natural selection in an animal host or in humans after zoonotic transfer. The timing of the most recent common ancestor of SARS-CoV-2 is estimated to be late November 2019 to early December 2019, aligning with the earliest confirmed cases. While laboratory manipulation is unlikely, further research is needed to confirm the origin of SARS-CoV-2. Studies of animal coronaviruses and more genetic and functional data on SARS-CoV-2 are essential to understand its evolution and prevent future zoonotic events. The ongoing surveillance of pneumonia in humans and animals is crucial for monitoring the virus's spread and impact.The origin of SARS-CoV-2, the virus causing COVID-19, has been the subject of extensive research. Analysis of the SARS-CoV-2 genome reveals features that suggest it evolved naturally rather than being created in a laboratory. Key features include an optimized receptor-binding domain (RBD) for binding to human ACE2 and a polybasic furin cleavage site in the spike protein, which may enhance viral infectivity. These features are not found in related betacoronaviruses, indicating natural selection in an animal host or in humans after zoonotic transfer. The RBD of SARS-CoV-2 is optimized for binding to human ACE2, suggesting natural selection in an animal host before zoonotic transfer. Bats are likely reservoir hosts, with RaTG13, a bat coronavirus, being closely related to SARS-CoV-2. However, its RBD does not bind efficiently to human ACE2, indicating further adaptation. Pangolins also show similarity to SARS-CoV-2, suggesting a possible intermediate host. The polybasic cleavage site and O-linked glycans in SARS-CoV-2 are not found in related betacoronaviruses, suggesting natural selection in an animal host or in humans after zoonotic transfer. The timing of the most recent common ancestor of SARS-CoV-2 is estimated to be late November 2019 to early December 2019, aligning with the earliest confirmed cases. While laboratory manipulation is unlikely, further research is needed to confirm the origin of SARS-CoV-2. Studies of animal coronaviruses and more genetic and functional data on SARS-CoV-2 are essential to understand its evolution and prevent future zoonotic events. The ongoing surveillance of pneumonia in humans and animals is crucial for monitoring the virus's spread and impact.