Evolution is the process by which populations change over long periods. Evolution is the explanation as to why there are multiple species today. One of the main pathways by which evolution occurs is natural selection. Many scientists today highly value natural selection’s impact in evolution; so much, that these scientists consider natural selection as the most important, if not the only pathway that drives evolution.
These scientists, who believe in the primacy of natural selection, are part of the adaptationist programme.
While natural selection certainly has contributed significantly to evolution, it is not necessarily the primary driving force behind evolution. By considering only natural selection when studying evolution, scientists overlook other reasonable conclusions based on the other driving forces of evolution. Thus, it is imperative to discard the adaptationist programme.
What is natural selection? As stated earlier, natural selection is one of the underlying processes of evolution. Darwin and Wallace separately proposed natural selection in the 1850s (Darwin and Wallace 1858).
In this early proposal, Darwin and Wallace described natural selection as “nature at war, one organism with another” (Darwin and Wallace 1858). The modern definition of natural selection does not deviate much from this. For the sake of simplicity, natural selection is essentially survival of the fittest. Organisms with traits favorable to the organism’s survival in a certain environment are most likely to reproduce. Over time, that trait becomes dominant to the population. Thus, the population has evolved.
This definition of natural selection may sound reasonable enough to accept the adaptations view toward evolution.
However, there are several limitations to this belief. First natural selection cannot account for why some bad alleles become fixed. Another limitation of natural selection is that it cannot explain why some seemingly isolated populations are not changing despite the selective pressures of the environment.
These, together with Gould and Lewontin’s argument regarding the spandrels of San Marco explain why the adaptationist programme is flawed. (Gould and Lewontin 1979). In addition, Gould and Lewontin added that atomizing the organism into multiple traits rather than looking at the organism as a whole while studying the organism’s evolutionary history will lead to the overlooking of plausible explanations (Gould and Lewontin 1979).
As Dawkins had argued in his book, “natural selection is the blind watchmaker (Dawkins 1996). However, watches are not yet finished once the maker finishes them. Other people add final additions to the watch. The jewelry store puts the watch in a good-looking box and finally, the buyer of the watch adds his or her own customizations into it. In the same way, evolution does not only work through natural selection. Other pathways such as genetic drift and gene flow (Gould and Lewontin 1979) are also used by evolution. Studying the evolutionary history of life by just studying natural selection is akin to being an outdoorsman just by looking outside the window all day.