The gene centered view of evolutionary change is a useful way to visualize how the processes work and to come up with explanations of why things happen the way they do. I have already mentioned concepts like genetic fitness, genetic lines and goals of an individual and this is where those concepts are grounded. This way of considering things was not originally put forward by Richard Dawkins but he certainly popularized it in 1976 with his book The Selfish Gene.
The usefulness of this method becomes apparent when you consider that we are use to thinking of species as individuals, discrete in time and space that act upon the world and are in turn themselves acted upon. But evolution doesn’t happen on the scale of individuals, a particular animal does not evolve the population does, and what produces this change in population characteristics? alterations in the genes. If we reverse our point of view and consider the genes as the primary actors in the evolution games things start to make more sense.
Genes are the true replicators in biological systems, while we may consider reproduction to be about continuing the legacy of an individual into the future in actuality it is the genes that are really being propagated. In addition it is the genes that change over time, not individuals even though in conversation it is useful short hand to refer to, say rabbits, evolving over eons it is really the genes and gene frequencies in the population that we are discussing.
Given that it is the genes that evolution is really concerned with we can start to put into context the concepts that we have been talking about up until now. In other words when we talk about behaviours or physical characteristics benefiting an individual what we mean is that it helps the individual’s genes survive and replicate and eventually spread through the species. More specifically the gene for that trait is selected by the environment of the individual to continue into the next generation.
In this way when a mutation alters the expression characteristics of a gene (eg making brown eyes blue for instance) it introduces variation in the population of genes and this new variant must compete against the other versions (alleles) in order to continue to exist (be passed on to the next generation). So when we consider how an adaption aids an individual we also need to think in terms of what activity is best for the genes because that is what will be maximized and optimized by nature, that’s just the way it works.
Yesterday: Kin Selection Tomorrow: Molecular Evidence