How even the greatest scientists can fall for cognitive bias

A HUNDRED years ago, scientists were sure of many truths. The greatest experts were certain that the universe had always existed and was always the size it is now. Most biologists were sure that proteins, not DNA, were responsible for heredity. Biochemists believed that, outside the nucleus, the interior of a human cell contained little more than busy enzymes – a "biochemical bog" that carried out all the reactions that are essential to life. These sureties were all wrong.