Recently it has been plausibly argued that mitochondria are, in origin, symbiotic bacteria who joined forces with our type of cell very early in evolution.
Similar suggestions have been made for other small bodies within our cells. This is one of those revolutionary ideas which it takes time to get used to, but it is an idea whose time has come. I speculate that we shall come to accept the more radical idea that each one of our genes is a symbiotic unit.
We are gigantic colonies of symbiotic genes.
One cannot really speak of ‘evidence’ for this idea, but, as I tried to suggest in earlier chapters, it is really inherent in the very way we think about how genes work in sexual species.
The other side of this coin is that viruses may be genes who have broken loose from ‘colonies’ such as ourselves. Viruses consist of pure DNA (or a related self-replicating molecule) surrounded by a protein jacket. They are all parasitic.
The suggestion is that they have evolved from ‘rebel’ genes who escaped, and now travel from body to body directly through the air, rather than via the more conventional vehicles—sperms and eggs.
If this is true, we might just as well regard ourselves as colonies of viruses!
Some of them cooperate symbiotically, and travel from body to body in sperms and eggs. These are the conventional ‘genes’. Others live parasitically, and travel by whatever means they can.
If the parasitic DNA travels in sperms and eggs, it perhaps forms the ‘paradoxical’ surplus of DNA which I mentioned in Chapter 3. If it travels through the air, or by other direct means, it is called ‘virus’ in the usual sense.