Selfish genes and reproductive fitness.

The 20th century saw two key discoveries in genetics. One took place in the laboratory and established the helical structure of DNA. The other was more of an intellectual revolution: the development of selfish gene theory, also known as gene centred evolution. Most doctors will be far more familiar with the first of these discoveries than the second. They would no doubt find it easier to explain how the DNA molecule winds round in a helix and makes a mirror image of itself, than they could expand on how genes can be said to be selfish. This emphasis on the physical properties of molecules rather than abstract theoretical ideas is perhaps understandable. Knowing the structure of DNA has certainly led to fantastic advances in biological science and in medicine. However, it may also have led us to ignore a set of ideas that may in time prove to be more profound in affecting our view of ourselves as human beings. I would place a bet on future generations seeing the recognition of the selfish gened and the related concept of reproductive fitnessdas an even greater scientific achievement than elaborating the spiral shape of nucleic acid. Selfish gene theory emerged gradually in the second half of the last century through the work of people like WD Hamilton, John Maynard Smith and George Williams, but has become mostly associated with the name of Richard Dawkins. He has contributed significantly towards it, but has also popularised the theory through writing so clearly and persuasively about it. Dawkins is the first to admit that the term ‘selfish gene’ may not be the best description of how genes work, since it carries unnecessary overtones of moral judgement. Genes are not selfish in the sense that they decide how to behave. They simply do what they do, which is to replicate, survive, and then replicate again. Although Dawkins has never suggested this as alternative term, the ‘dedicated duplicator ’ might be a better one.