The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [46]
None of this would have been possible for society without laws to enforce the social interest over the individual, selfish drive; it was the same with genes. A gene has only one criterion by which posterity judges it: whether it becomes an ancestor of other genes. To a large extent it must achieve that at the expense of other genes, just as a man acquires wealth largely by persuading others to part with it (legally or illegally). If the gene is on its own, all other genes are its enemies: every man for himself. If the gene is part of a coalition, then they share the same interest in defeating a rival coalition, just as employees of Boeing share the same interest in its thriving at the expense of Airbus.
This broadly describes the world of viruses and bacteria. They are disposable vehicles for simple teams of genes, each team highly competitive with other teams but with largely harmonious relations between team members. For reasons that will soon become apparent, this harmony breaks down when bacteria merge to become cells and cells merge to become organisms. It has to be reasserted by laws and bureaucracies.
And even at the bacterial level it does not entirely hold true. For consider the case of a new, supercharged mutant gene that appears in a bacterium. It is superior to all other genes of its type, but its fate is determined largely by the quality of its team. It is like a brilliant engineer finding himself employed by a doomed, small firm, or a brilliant athlete stuck in a second-rate team. Just as the engineer or the athlete seeks a transfer, so we might expect that bacterial genes would have invented a way to transfer themselves from one bacteria to another.
They have. It is called conjugation, and it is widely agreed to be a form of sex itself. Two bacteria simply connect to each other by a narrow pipe and shunt some copies of genes across. Unlike sex it has nothing to do with reproduction and it is a relatively rare event. But in every other respect, it is sex. It is genetic trade.
Donal Hickey of the University of Ottawa and Michael Rose of the University of California at Irvine were the first to suggest in the early 1980s that bacterial ‘sex’ was invented not for the bacteria but for the genes – not for the team but for the players.6 It was a case of a gene achieving its selfish end at the expense of its team mates: abandoning them for a better team. Their theory is not a full explanation of why sex is so common throughout the animal and plant kingdoms; it is not a rival to the theories discussed heretofore. But it does suggest how the whole process got itself started. It suggests an origin for sex.
From the point of view of an individual gene, then, sex is a way to spread laterally as well as vertically. If, therefore, a gene were able to make its owner-vehicle have sex, it would have done something to its own advantage (more properly, would be more likely to leave descendants if it could), even if it were to the disadvantage of the individual. Just as the rabies virus makes the dog want to bite anything, thus subverting the dog to its own purpose of spreading to another dog, so a gene might make its owner have sex, just to get into another lineage.
Hickey and Rose are especially intrigued by genes called transposons, or jumping genes, that seem to be able to cut themselves out of chromosomes and stitch themselves back into other chromosomes. In 1980 two teams of scientists simultaneously came to the conclusion that transposons seemed to be examples of ‘selfish’ or parasitic DNA, which spreads copies of itself at the expense of other genes. Instead of looking for some reason that transposons exist for the benefit of the individual, as scientists had done