Chapter Chapter-by-Chapter Anaylsis of The Selfish Gene (1989 edition) - Study Guide by Richard Dawkins

is small enough to survive processes such as crossing over and last for enough generations to serve as a unit of natural selection. He writes; "The more likely a length of chromosome is to be split by crossing- over, or altered by mutations of various kinds, the less it qualifies to be called a gene in the sense in which I am using the term". He points out that a cistron may qualify as a gene under this definition, but then so may larger units. For example, a dozen cistrons may be so close to each other on a chromosome that for our purposes they constitute a single long-lived genetic unit.

In the second half of the chapter, Dawkins argues that it is the genes that are the immortals. He says: "We, the individual survival machines in the world, can expect to live a few more decades. But the genes in the world have an expectation of life that must be measured not in decades but in thousands and millions of years." He argues that this is why the individual cannot be considered as the unit of natural selection. They are just unique temporary entities that are only present in one "human" lifetime and it is not possible to get evolution by selecting between entities when there is only one copy of each entity. But the genes survive from one generation to the next, albeit in different bodies and different environments but they themselves are unchanged.

However, one can really only talk of the gene’s potential immortality. A gene could live for millions of years, existing in the form of many duplicate copies, but many new genes do not make it past their first generation. Those that do survive are partly lucky (because they have not found themselves in the same body as a lethal gene), but mainly because they have what it takes, i.e. they are good at making survival machines. This means they "build" themselves (through embryonic development) bodies that are equipped with as many beneficial characteristics for their environment as possible, whether this is long legs for running, or sharp teeth for eating meat. More universal properties that are particularly relevant for this book are; altruism is bad and selfishness is good. Dawkins reiterates this idea when he says: "Genes are competing directly with their alleles for survival, since their alleles in the gene pool are rivals for their slot on the chromosomes of future generations. Any gene that behaves in such a way as to increase its own survival chances in the gene pool at the expense of its alleles will, by definition, tend to survive. The gene is the basic unit of selfishness."

However, having said this, Dawkins points out that the effect of each individual gene is largely dependent on the other genes in the same body, and therefore the success of the gene will be affected by it’s compatibility with them. He illustrates this idea with the analogy of the Oxford-Cambridge boat race. One oarsman cannot win the race on his own; he needs eight colleagues. Rowing the boat is a co-operative venture but invariably some men are better at rowing than the others. Selection for the oarsmen depends on the individuals rowing expertise and their compatibility with the other eight members of the boat. Dawkins uses the oarsmen to represent the genes and the boat to represent the chromosome. The gene for each seat in the boat is chosen from the rival alleles, and the gene is selected for its successful survival machine and because it can cooperate well with most of the other genes.

The gene machine

Survival machines began as passive receptacles for the genes, providing them with little more than protection. They "fed" on the organic molecules in the primeval soup but eventually, this source of "nourishment" ran dry. As they became more elaborate and developed due to the environmental pressures, they evolved into many-celled bodies, each cell containing a complete copy of the genes. Dawkins likes to refer to this state of the vehicle as "a colony of genes, and of the cell as a convenient working unit for the chemical industries of the genes". However, he is careful to point out that bodies have undeniably acquired an individuality of their own; animals move as a co-ordinated whole, as a unit and not as a colony. Dawkins argues that this is to be expected as selection favours genes that co-operate with others so that the communal body is as successful as possible. Indeed, nowadays the mutual co-evolution of genes has proceeded to such an extent that the colonial nature of an individual is unrecognisable. Therefore, in this chapter he starts to use "the language of convenience" and refers to the individual body as an agent "trying" to increase the number of all its genes for future generations.