In Darwin’s time, it was believed that selection occurs at the level of an individual – that an entire creature is either selected or not. But as we learn more about what we are made of, we realize that the entire concept of an individual is somewhat illusory. Every macro-creature is not a stand-alone individual but rather a construction of millions of smaller transitory creatures that use its body as a vessel. The only way in which these creatures are working towards a common goal is in protecting this body from foreign invaders. The genes, the true residents of the body, are here only to make it to the next generation. They don’t necessarily care if other genes on parallel loci make it with them or not; they simply care about themselves.

To accomplish their goal, they network with each other in a complex hierarchy. We can compare the workings of this network to that of a corporation. Just like companies have CEOs, executives, managers, and workers to look after their daily operations, the body has various genes working at different levels of control. This hierarchy in the body is called its pleiotropy. The senior genes have the power to shut down, change, suspend, or accelerate operations based on the needs of the body. This system allows the “critical stages” of development as discussed in a previous article.

In corporations, several people work together to accomplish something an individual cannot accomplish by themselves. These genes in our bodies are doing the same thing. By working in a network, the composite bodies of these genes accomplish seemingly magical tasks – such as thought and communication. On a broad scale, all bodies involved in the network affect the workings of all other bodies surrounding them, quite intimately.

The nucleus of all somatic cells in the body contain two pairs of genes – they are diploid. One pair from the father and one from the mother. The only cells in the body that are haploid (one set of genes) are the sex cells. Textbooks teach that the genes that make it to these cells are there by “random selection”. But of course we know that is not how it works. In reality, every gene is fighting for its place on a chromosome. This is called it’s ‘meiotic drive’ – it’s drive to be included in the process of meiosis.

The fight can rise to such dramatic proportions that some genes could even take a position that is damaging to other genes, or even the rest of the cell. In “The Extended Phenotype”, Richard Dawkins calls such genes ‘outlaws’ (not his term originally). It is in the interest of the rest of the genes of the cell to subdue this outlaw. So here, we see a collective effort emerge between genes at other loci to make sure that the outlaw is not selected. But on the other hand, any outlaw that can somehow beat the system is greatly increasing its chances of making it to the next generation, so selection would certainly favour it greatly.

Things become more interesting however when outlaws appear on sex chromosomes. Any driving gene on an X or Y chromosome, could easily alter sex ratios drastically and hence even lead a population to it’s demise. If a Y-driving gene is successful enough, the next generation will see only males being born (in mammals for example) leaving them no one to mate with. This method has also been tested as a weapon against pests. In labs and simulations, the introduction of an intentional outlaw driving towards a particular sex, destroyed the entire population in as few as four generations.

The workings in nature of one such outlaw have been witnessed in mud-daubing wasps. The females of this species build their own nests, lay a prey in it for their new-borns to feed upon, lay their eggs on the already dead or dying prey, seal the nest, and then begin the cycle again. As opposed to most other wasps, the males here are also present at the laying and in fact, during it, force the female into a strange ritual dubbed ‘holding’. The whole process begins when the female, having already laid the prey in her nest, goes head first into it with her abdomen facing outside. The male, who is outside, then copulates with her in this position. Then the female turns around, pops her head outwards from the nest and faces her abdomen inside it. She feels for the prey with the tip of her abdomen as if about to lay her egg. At this point, the male grabs her head with his forelegs and proceeds to pull her antennae outwards for about half a minute, to prevent the lady from dropping her egg just yet. Then the female again turns around and copulates with the male, only to turn around again and make another attempt to lay her egg. The male does the same thing. This repeats several times until the female finally gets to lay her egg.

It is hypothesized that the male here is trying to influence the sex of the egg. In Hymenoptera, unfertilized eggs usually result in males and fertilized ones in females. So perhaps by not letting the female lay her egg immediately, the male is trying the make sure it has time to fertilize in the oviduct, or perhaps he is trying to overflow her internal tracts with sperm, so the egg has more of a chance of fertilizing. Both of these actions would lead to a greater chance of new born being a female, giving the male more mating opportunities. Of course, the resistance of the female is necessary, not only because more unfertilized eggs mean more males for her, but also because without it, the entire population might perish.

In ways like these, outlaw genes and other interesting types (segregation distorters, other germ-line replicatiors) cause strange behaviours in our world, and make evolution seem even more implausible. But as always, there are breakthroughs and paradigm-shifts in Science that show us the way. “The Extended Phenotype” is a brilliant book, and deals with several such cases, and all in all, gives one a wonderful perspective of genetics. Dawkins had said before that he considers this book to be his best work; I don’t know if he still considers that true, but if you’re looking to do some interesting reading on evolution, there is no better book I could recommend than this.