Is the direction in which plants and animals in the natural world are evolving always progressive? Examine the opposing arguments of Dawkins and Gould to see if the increasing complexity of life can be interpreted as progress.
Are plants and animals in the natural world evolving in a progressive direction? In the past, we have assumed that body structures and brains have evolved over time in a self-evident direction of increasing complexity, but reading Darwin’s Table by Korean professor Dae-Ik Jang has given me the opportunity to rethink whether evolution is progress. This book offers readers a new perspective through a fictionalized debate between two scholars with opposing views on whether evolution is a progressive process. Richard Dawkins argues that living things evolve in a progressive direction, and Stephen Jay Gould argues that evolution has no specific tendency.
Dawkins argues that the evolution of life has been a process of increasing complexity, from single-celled bacteria 3.5 billion years ago to the many forms of higher life today. Dawkins sees evolution as naturally moving in the direction of progress, as organisms from simple forms have developed increasingly complex body structures and sophisticated brains. For example, the structure of the human brain is far more sophisticated than that of a bacterium, and billions of years of evolution have resulted in increasing complexity.
Gould, on the other hand, believes that evolution is simply the result of undirected variation. He argues that life has merely adapted and changed to fit its environment, but not with a progressive purpose. To illustrate this, Gould uses the “drunkard model”. Just as a drunken person leans against a wall and moves randomly while walking, gradually moving away from the wall, evolution is directionless, but over time it appears to be progressing. Through this explanation, Gould argues that the fact that life appears to have evolved in a certain direction is merely the result of natural selection and mutation, not progress.
One student who read the book and agreed with Dawkins’ view argued that the evolution of life has progressed by increasing complexity. The student’s view is that “as the number of cells increases, the ability of an organism to perform increases, and as a result, evolution is progressive in the direction of increasing complexity,” and he attempts to demonstrate this through a variety of examples. For example, he cites the case of the worm losing its legs and gaining the ability to regenerate, arguing that the degenerated part is replaced by another form of ability, supporting the direction of evolution. The student cited the human appendix as a similar example, explaining that although humans have gained an unnecessary organ, the overall body structure has evolved to perform more complex and efficient functions.
But there’s a logical fallacy here. The worm’s legs and ability to regenerate are independent outcomes of its adaptation to its environment, each requiring a different function. If the worm were to be reintroduced to an environment that required legs, it would likely develop legs only, regardless of its ability to regenerate. Similarly, the efficient functioning of human organs in pairs has nothing to do with the degeneration of the appendix; it is the principle of natural selection that eliminates unnecessary organs and develops the necessary ones. Therefore, the process of changing the functions of organisms is the result of responding to the essential requirements of survival, and cannot be considered evolution with a specific direction.
The student also argues that evolution has “developed in the direction of progression of capabilities themselves. The student sees the progression from early bacteria to prokaryotes to eukaryotes to multicellular organisms, and sees the improvement of these abilities as progressive. However, this argument is inconsistent with the ‘drinker model’ of evolution. Even if evolution has increased complexity over time, this could be the result of undirected natural selection, and it would be a stretch to conclude that evolution itself is progress.
To argue that evolution is directed progress, we need evidence other than just complexity. For example, there are cases where complexity does not increase in a given environment, but rather decreases as the environment changes. For example, changes in the natural environment, such as climate change with repeated ice ages and thawing periods, can cause organisms to adapt in either a progressive or regressive direction. For example, the human hearing system in an overly noisy environment may degenerate, or it may evolve to overcome the noise. In this way, adaptations in living things can lead to an increase in complexity, but not necessarily in a progressive direction.
Dawkins’ theory of progressive evolution makes intuitive sense, but it requires additional evidence to explain the direction of evolution. Gould’s argument, on the other hand, can be explained using complexity graphs and McShay’s ‘controlled trend’ and ‘passive trend’. Indeed, complexity graphs show that bacteria represent the largest proportion of all life, with higher organisms representing a very small proportion. This suggests that only a small fraction of them may have evolved into complex forms by chance through various mutations. Evolution is the result of random variation being selected for in a particular environment, and the temporary complexity of a particular organism within that variation is not necessarily progress.
