SARS-CoV-2 is the seventh #coronavirus known to infect humans. The receptor-binding domain (RBD) in the spike protein is the most variable part of the coronavirus genome. On the basis of structural studies, and biochemical experiments SARS-CoV-2 seems to have an RBD that binds with high affinity to receptor ACE2 from humans cats and other species with high receptor homology. The high-affinity binding of the SARS-CoV-2 spike protein to human ACE2 is most likely the result of natural selection on a human or human-like ACE2 that permits another optimal binding solution to arise. Thus there is strong evidence that SARS-CoV-2 is not the product of purposeful manipulation.