Evolution: not a Theory

Carl Sagan once said, “Evolution is a fact, not a theory.” And he was partly right; evolution is not a theory. He’s not right about evolution being a fact of course…. This is the idea that all life on earth is descended from a common microbial ancestor: that the information in our DNA is entirely the result of mutations over time that happened to convey survival advantage. It is this version of evolution that is neither a fact nor a theory.