Immortal Coils

The Selfish Gene: Chapter 3 summary

DNA, or any other DNA-like molecule that replicated itself at the dawn of life might not have been the first replicator molecule. Dawkins makes mention of A. G. Cairns-Smith's suggestion "that our ancestors, the first replicators, may have been not organic molecules at all, but inorganic crystals-minerals, little bits of clay." This may well be true but the DNA molecule is the clear victor of the replicators, it persists through every living organism (or "survival machines") on earth.

As shown above, the DNA molecule consists of 4 nucleotide bases in a long chain double helix. Every single cell in our body contains a complete copy of our genetic information with the acception of cells that go through meiosis and only contain half (23 chromosomes) of our original 46 chromosomes. This simple four-letter alphabet indirectly controls the manufacture of our body and more importantly, it's a one way path, any wisdom, skills, or knowledge learned in you life will never be translated back to genetic code. This is important to note because it means that genes are then responsible (at least in part) for their own survival in their efficiency of what survival mechanism (body) they create. Now, one might think it would be better to describe the "replicator" that controls this symphony of creation as a single large genetic unit, or genetic complex. This would be fine if it wasn't for sexual reproduction and the crossing over of two genetic pairs that make up a random collection of genes from both parents during meiosis. Each body is only momentary storage space for a short-lived collection of genes. Although our bodies (and their specific collection of genes) my only life for a century, the individual gene may continue for millions of years.
Dawknis goes on to explain in greater detail how meiosis provides us a random assortment of genes from our grandparents and how a single "gene" doesn't have a specific definition. He defines it as "any portion of chromosomal material that potentially lasts for enough generations to serve as a unit of natural selection." If a single genetic unit can replicate with high copying-fidelity, it will persist within a population, or in many species for many generations and we can call that a gene.
The "potential" for a gene to live for hundreds of millions of years make it a good candidate as a unit of natural selection. Some genes don't make it past one generation though when others continue on. This is partly luck but mostly that these particular genes are proven good at making survival machines. Any gene that aids in someway to the survival of the machine will increase the chances of survival and reproduction of that individual. In this case, it would only make sense to conclude from this that it would be detrimental to a genes survival for it to act altruistically. "The gene is the basic unit of selfishness."
In order for an organism to develop its body though, many genes need to work in unison to accomplish a single task such as building a leg. There is no specific gene that builds a leg, a number of genes and the external environmental factors end up determining the end result of say the length of one's legs. The exception is that their may be a specific gene that, with everything else constant, will increase the length of the leg.
This may seem paradoxical when compared with the earlier assumption that each gene is selfish and competing for its survival. Dawkins explains that this isn't the case because one of the good qualities of a gene would be to work together with others in addition to being good at whatever the gene is meant for. The ultimate quality of a gene is determined by other genes, its ability to cooperate with everyone else.