[ This post in number 1 of a series. They will be of interest mainly to those who've read Richard Dawkins' book, The Selfish Gene. I recommend they be read in order. ]
In The Selfish Gene, his fascinating bestseller, Richard Dawkins advances the theory that natural selection is not the result of competition among species. Instead, he says, genes compete with each other, and the creation, extinction and evolution of species is an indirect result of the competition of these "selfish" genes.
I am running an extreme risk of presumption (I'm not a biologist), but I'm going to propose a "friendly amendment" to Dawkins argument, one that more closely defines the "goal" of the "selfish" gene. It's my hope that it increases the explanatory power of Dawkins' brand of neo-Darwinism, solves a few mysteries and adds precision to his argument. First, I want to very briefly sketch that part of Dawkins' argument most relevant to mine.
Again, Dawkins identifies the gene, not the species, as the "unit of selection". He's not splitting hairs, but distinguishing real differences. The "selfish gene" explains a lot of behavior that from the species-selection point of view is mysterious. For example, as I write this I am looking at two nests put up as part of an effort to restore bluebirds to their original habitat here in Berkshire County, Massachusetts. Bluebirds compete for these nests with tree swallows, who are small enough to fit nicely into the nest, and large enough to win most fights with bluebirds.
So far, it sounds like the old "survival of the fittest species" story and bad news for bluebirds. That's why two bluebird nests were put close together. A tree swallow family may get the first nest, but let another tree swallow family show up and the first tree swallow family will chase off the newcomers. Tree swallows don't want competition for the airborne insects they feed on. Bluebirds feed on ground-dwelling insects, so tree swallows don't compete with them for food and don't mind if they nest nearby. It is easy to interpret the tree swallow's behavior as promoting the survival of its own genes, and very difficult to see in it any concern for the survival of the larger gene pool of its species.
The difficulty that I found in Dawkins is this: he ascribes two different goals to his "selfish genes". Most of the time they are said to be maximizing "survival" (The Extended Phenotype, p. 233) but sometimes they are described as striving to "increase" (Phenotype, p. 84). When he turns from theoretical statements to examples, Dawkins seems to reverse this preference. The genes in his examples usually strive to increase the number of "germline" genes. (Germline genes are those actually in reproductive lineages.)
Just as with species vs. gene, survival vs. increase is a distinction with a difference. To make an analogy with investment, some investments are best for capital preservation (survival), while others promise higher returns (increase) in exchange for higher risk. Under normal economic conditions, no investment is optimal for both goals. A mathematical model optimizing for the probability of survival of a gene will not be the same as one seeking to increase gene count. Which of the two models genes obey should be testable, but in advance of that I believe we can make a very strong guess.
Closely related to the "increase" vs. "survival" question, is the question of the exact nature of "the unit of selfishness". It's the "gene", but "the gene" can either be the collection of all genes with the same phenotype at the same place in the chromosome (which I'll call the gene-type), or one individual member of that collection (which I'll call the gene-copy). While the English language is ambiguous, Dawkins is not. His examples and his more detailed explications clearly show that he thinks the gene-type is what is "selfish", and that gene-copies subordinate their individual interests to the gene-type.
It's possible Dawkins sees the interests of the individual gene-copy and its gene-type as identical in practice. They are not. The individual germline gene-copy has no interest in increasing the germline population count of its gene-type -- it's only interested in its own survival. If survival is really the goal, Dawkins is not allowing individual gene-copies to be selfish enough. The gene-copy has no reason to "care" about identical copies of itself elsewhere, unless it can use them as a means to the end of its own survival.
Of course, DNA and genes aren't conscious and don't "care", "plan" or have "goals", except within the framework of a metaphor I follow Dawkins in finding useful. (In a later post, I'll "lift the hood" on this metaphor.) In the next posts, I will show that in the struggle between these two goals, "survival" and "increase", to describe natural selection according to Dawkins, one emerges as clearly the fittest.