Microbiology and Cometary Panspermia in Context

Abstract

Geochemical studies of carbon isotopes in ancient rocks show clear evidence of microbial life. Microbial life appeared suddenly on the primitive Earth about 3.9 to 4 billion years ago. How did a planet with no microbial life suddenly come to have microbial life? The existence of microbial life on Earth does not imply that it originated here. Furthermore, by any reckoning, the chance transformation from organic molecules to microbial life is exceedingly improbable. The overwhelming complexity of even the simplest microorganism indicates a cosmic origin.