Richard Dawkins claims that evolution occurs gradually by cumulative selection on a selfish gene-by-gene basis. However, if we analyze his logic, we can see that evolution is more likely to occur in discontinuous equilibrium than cumulative selection. We use the example of the Weasel Program and the concept of ESS to refute Dawkins’ argument.
In his perhaps most famous book, The Selfish Gene, Richard Dawkins argues that natural selection occurs in units called “selfish genes.” In another book, The Blind Watchman, he states that “the theory of evolution by gradual ‘cumulative’ natural selection is, as far as we know, the only theory that can explain in principle the existence of organized complexity,” and that the accumulation of mutations leads to the emergence of new mainstream traits through natural selection. Taken together, these arguments lead to his definition of evolution as ‘the gradual accumulation of natural selection at the level of selfish genes’.
I disagree with the former of his claims, that natural selection occurs at the gene level, and I don’t necessarily think that the gene is the only unit of natural selection. However, I do agree that “selfish genes” criticizes evolutionary theories based on individual or group-centered natural selection and emphasizes that genes can be subject to it, and may even prevail in terms of importance. However, he disagrees with the latter argument, that cumulative selection explains the existence of complexity and results in gradual evolution, and we will use his logic to show that evolution caused by selfish genes can never be gradual by cumulative selection, but rather is characterized by interrupted equilibrium.
In On the Origin of Species, Darwin once confessed that when discussing the function of the eye and its complexity, ‘it seems to me quite absurd, given all these functions which cannot be easily imitated, that the eye could have been formed by natural selection’. Dawkins proposes that gradual evolution by cumulative selection is the answer to Darwin’s problem of explaining the complexity found in living things. In The Blind Watchmaker, Dawkins explains how evolution occurs: “Evolution results from changes in the frequency of genes, which, over generations, determine which of the various contents of each storage site in DNA prevails. So we can interpret Dawkins as explaining that cumulative selection has gradually caused certain genes to become more frequent. He gives the “Weasel Program” from The Blind Watchmaker as an example to illustrate this. What are the odds that a monkey could produce the phrase “METHINKS IT IS LIKE A WEASEL” by combining random letters and blank spaces in one go? According to Dawkins, it would be 1/27^28, or about 1/10^40, but if he typed a letter or blank that matched the target sentence and didn’t change it, he could produce the target sentence very quickly after a few iterations. In other words, gradual evolution by cumulative selection that leaves the right elements behind is possible, and the Weasel Program is a program that simulates this. In fact, after 47 iterations, he came up with the target sentence, “METHINKS IT IS LIKE A WEASEL.” He argued that a similar principle applies to the process of evolution, and extrapolating from this logic, he concluded that “the eye has evolved independently in different parts of the animal kingdom at least 40 times and possibly as many as 60 times. But how does the principle of the Weasel Program fit in with his earlier claim that the unit of natural selection is the selfish gene?
In Chapter 5 of The Selfish Gene, “Aggression-Stability and the Selfish Machine,” Richard Dawkins uses the concept of an “Evolutionarily Stable Strategy,” or ESS, to describe the process of natural selection. An ESS is a strategy that, once adopted by most members of a population, cannot be surpassed by any alternative strategy, as Dawkins explains in The Selfish Gene on page 139: “But once a strategy becomes an ESS, it remains an ESS. Natural selection will punish strategies that deviate from it. Let’s apply these concepts to the Weasel Program. In the Weasel Program, each letter and space is a gene, and the sentences that are formed from them correspond to strategies, and therefore to objects. So, what does it mean to have a target sentence? It can be interpreted as having a purpose and direction in evolution. In particular, it is a clear fallacy to assume that evolution had a purpose and direction prior to the conscious being named Richard Dawkins. If a conscious being gave a creature a direction and purpose for evolution, he could not have done so unless he was God. If we assume one of the ESSs, “this is how evolution works,” rather than a purpose and direction, then the explanation goes something like this.
The very first randomly generated sentence by the Weasel Program was ‘WSC UDZHGQQFBSJCVKOBBXP AVND’. Let’s call this generation 0. In generation 0, there were three matches, but in the next generation, the sentence was ‘WSC UDZHGQQFBSJCVKOBAXP AVND’, and we can see that the number of matches increased to four. Interpreting this, we can see that the generation 1 strategy was superior to the initial generation 0 strategy. Following Dawkins’ logic, it stands to reason that Generation 1, with its higher match rate, should have been selected over Generation 0. Therefore, Generation 1 must have achieved ESS and had an overwhelming advantage in the gene pool. What is ESS? When a strategy is adopted by most members, it cannot be surpassed. So you can see that evolution from generation 1 to generation 2 is impossible. If a second-generation strategy were to emerge, it would surely be overtaken by the first-generation ESS.
However, there is an explanation that could neutralize this. As he points out in The Selfish Gene, there can be many ESSs in a population. And if there are many, they will fixate on the one that first gathers a large enough population to reach a steady state. Therefore, after the first generation appears, it is possible for the second generation to appear and form the ESS before the first generation reaches the ESS. Of course, it is possible to form an ESS as long as the second generation appears. This is because the higher the match rate with the target sentence, the higher the chance of survival, and the more likely it is to evolve into the target sentence. However, we are still far from the target sentence. The third generation must appear before the second generation implements the ESS, and this must continue until generation 47. In other words, the Weasel Program is a simulation that assumes that evolution must occur sequentially to generation 47 in a very short time, during which time no extinction by natural selection occurs, and then the moment generation 47 appears and implements the ESS, natural selection must wipe out the remaining generations. This seems to lend weight to Richard Dawkins’s theory of gradualism, rather than to the theory of disruptive equilibrium, where organisms remain largely unchanged for long periods of time and then undergo rapid speciation over a short period of time.
This error does not occur because the Weasel Program is a fundamentally flawed example, but because the very concept of ESS makes gradualist evolution fundamentally impossible. In The Selfish Gene, we read the following “Since all the other individuals except that one are also trying to maximize their own success, the only strategy that can persist in the long run is one that, once it has evolved, no other strategy can gain more advantage than it. ‘ At first glance, it seems self-evident that ESS satisfies the above conditions very well, and selfish genes would certainly want to be selected for by implementing ESS. However, if an environmental change occurs and there is a period of instability, there will be a competition among many mutational strategies that have been pushed out by the ESS, and the surviving strategies will form the ESS again and evolve in a short time. In this way, the evolution caused by selfish genes is bound to be a short-lived, rapidly changing, stochastic equilibrium.
