In 1957, a few years after he co-discovered the double helix, Francis Crick proposed a very famous hypothesis. It states that "once 'information' has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible." After it had proven to form the foundation of molecular biology, he later called this hypothesis the "Central Dogma" of biology.
In the last years of the last millennium, Crick's dogma fell. The reason? Direct protein-to-protein information transfer was found to be possible in a class of proteins called "prions." With the aid of a catalyst, prions (short for "proteinaceous infectious particles") cause another molecule of the same class to adopt an infectious shape like their own simply through contact. Thus, prions are an important and only recently discovered mechanism for the inheritance of information through means other than DNA. Such an important discovery merited a recent Nobel Prize for Stanley Prusiner, who doggedly pursued the possibility of a rogue biological entity replicating without the assistance of genes against a back-drop of resistance and disbelief among most of his colleagues. Further testimony to the significance of prions comes from the current BSE crisis in Europe. Now that we know how they work, prions — and the diseases they cause — may begin popping up all over the place.
ROBERT AUNGER is an anthropologist studying cultural evolution, both through the now much-maligned method of fieldwork in nonwestern societies, and the application of theory adapted from evolutionary biology. He is at the Department of Biological Anthropology at the University of Cambridge, and the editor of Darwinizing Culture: The Status of Memetics as a Science.