In this blog post, we examine the various debates surrounding evolution and ponder whether it is scientific fact or mere coincidence.
The theory of evolution is one that most people living in the modern world have heard of at least once. Although over 150 years have passed since its publication, significant and minor controversies still exist. Broadly speaking, there is conflict between religious believers, particularly those supporting creationism, and the scientific community that supports evolution. More specifically, there are opposing theories within the broader framework of evolution itself. However, the conflict between creationism and evolution is fundamentally a clash between the different approaches of science and religion, making it logically difficult to resolve completely. Comparing the two is seen as meaningless. Therefore, this article aims to examine the various theories within evolutionary theory from a scientific perspective and present the author’s opinion.
To explore what constitutes established theory within evolutionary theory, the discussion will proceed based on several major points currently debated within the field. This article plans to develop its argument centered on considerations regarding the timing of evolution, the units of evolution, positions on the role of genes, views on adaptation, and the relationship between evolution and progress.
Evolution is commonly understood as the process where individuals better adapted to their environment survive through natural selection, and their traits are inherited, leading to evolution. However, delving deeper reveals much to consider. First, let us examine the timing of evolution. On this topic, the theory of punctuated equilibrium and gradualism are largely opposed. The theory of punctuated equilibrium explains that the evolution of biological species occurs through rapid differentiation during specific short periods. It posits that in populations larger than a certain size, even if mutations occur, significant change is difficult due to gene flow between groups. However, when small populations become isolated, the influence of gene flow diminishes, allowing differentiation through mutation to occur. Conversely, gradualism views evolution not as such abrupt differentiation, but as continuous differentiation occurring at varying speeds.
For example, consider the Israelites’ return journey to Israel, covering approximately 320 km over 40 years. According to the punctuated equilibrium theory, the Israelites would have remained settled for most of the time, then rapidly moved the 320 km at some point. The gradualist theory, however, would view them as advancing steadily in a consistent direction over the 40 years until they reached Israel. A crucial point to note in this analogy is that gradualism does not claim they moved steadily for 40 years, but rather that they advanced with directionality throughout that period. Therefore, I sympathize more with gradualism. While punctuated equilibrium posits rapid divergence at specific times, from a gradualist perspective, such phenomena can ultimately be interpreted as part of a long-term process of change. Evolution occurs continuously, whether slowly or rapidly. Therefore, I believe gradualism, which can encompass other theories, offers an explanation closer to the truth.
Next, let’s discuss the units of evolution. On this topic, Dawkins supports gene selection theory, while Gould advocates multilevel selection theory. Multilevel selection theory views genes, individuals, and species as all units of evolution, so it might seem like a higher-level theory than gene selection theory, but this is not a simple matter. The crux lies in determining at which level natural selection operates. Since the traits of individuals and species ultimately derive from the phenotype of genes, even if individuals and species are considered units of natural selection, they are no different from what is selected at the gene level. In his book The Selfish Gene, Dawkins explains: “The gene indirectly controls the behavior of the survival machine, like a computer programmer who does not directly manipulate the doll. What genes can do is design the survival machine in advance. After that, the survival machine operates independently, and the genes exist passively within it.” In other words, even if individuals and species undergo natural selection, this can be seen as a result influenced by genes. From this perspective, I find gene selection theory more persuasive.
The following is a discussion on the role of genes, a core topic in evolutionary theory. If this aspect is clearly elucidated, questions regarding the timing of evolution, the units of evolution, and the scope of adaptation (how far to consider something an adaptation) would also be resolved. However, the debate over the precise role of genes is still ongoing, and active research is being conducted. Dawkins views genes as exerting a major influence on the phenotype and as the primary agents of evolution, while Gould argues that both the internal and external environments of an individual, not just genes, are crucial. Studies comparing the effects of genetics and environment in twin research continue, but since the ratio of genetics to environment varies depending on the topic, it is difficult to definitively assert that either genetics or environment holds absolute primacy. For example, studies on prosocial behavior showed genetic factors increased from 32% to 61% with age, while the influence of the shared environment decreased from 47% to 3%. Therefore, while Dawkins’ gene-centric perspective may be meaningful for fundamental biological traits, I sympathize more with Gould’s position because the influence of the environment on an organism’s growth and survival cannot be ignored.
Next, let’s examine the debate surrounding adaptation. Adaptation is one of the primary driving forces of evolution. This is because organisms that adapt well to their given environment survive better due to natural selection. However, determining the exact scope of adaptation is not straightforward. Take human language ability as an example. Dawkins argues that language emerged as an adaptation, with individuals who used language surviving and passing on their traits. Gould, however, contends that language arose as a byproduct of the human brain becoming larger and increasing its processing capacity. Of course, the possibility exists that language could be an adaptation, given that genes influencing language do exist. Another example is rape. Adaptationists view it as an adaptive behavior for males who fail to reproduce, while anti-adaptationists see it as merely a byproduct of selfish behavior. The existence of insects like the ‘biting fly’ with rape organs supports adaptationists, whereas the fact that rape occurs even with females and children far removed from reproductive age supports anti-adaptationists. To clarify this debate over the scope of adaptation, additional research is necessary, and a definitive answer will only emerge once sufficient groundwork is laid. Therefore, rather than mutual recrimination, it is currently essential to gradually clarify matters through research.
Finally, I wish to conclude by discussing evolution and progress. The relationship between evolution and progress can vary depending on how ‘progress’ is defined. Since the term ‘progress’ itself carries value judgments, it inevitably assigns value to the phenomenon of evolution. If progress is defined as an increase in biological diversity, then evolution could be seen as progress. However, it is questionable whether we can definitively assert that higher organisms like multicellular life are progressive. As Gould explained through his ‘drunken sailor model,’ the current evolutionary trajectory toward complex multicellular life exists because of the barrier posed by single-celled organisms; it cannot be definitively claimed that this trajectory itself signifies progress. I believe humanity must exercise caution when applying value judgments of progress to the phenomenon of evolution. While positively accepting humanity’s emergence through evolution is commendable, misguided value judgments—like how early imperialists misused Darwin’s theory to claim their own superiority—can cause significant repercussions.
Thus far, I have discussed the controversies surrounding evolutionary theory, focusing on the perspectives of Dawkins and Gould, who can be considered Darwin’s successors, and presented my own thoughts. While future research will clarify and resolve many issues, debate will persist throughout this process. My hope, however, is that this debate fosters a healthy competitive effect, reducing errors in research and contributing to our approach to truth. The recent wasteful debates where religious circles bring up theistic evolution to criticize the scientific community do not aid progress. If we are true descendants of Darwin, we must explore evolutionary theory through scientific argumentation. Perhaps, someday, humanity might discover the absolute truth that some scientists dream of.
