Is the natural world really moving in a progressive direction? How do Richard Dawkins and Stephen Jay Gould’s views on evolution differ?

After reading the book Darwin’s Table by Korean professor Dae-Ik Jang, I wondered if the natural world is really moving in a progressive direction.

 

Are plants and animals in the natural world evolving in a progressive direction? Until now, I used to think that the body structure and brain have evolved in the past in a way that naturally increases in complexity over time, but reading Darwin’s Table by Korean professor Daeik Jang has made me think differently. The book introduces a fictional debate between two opposing sides of the debate on whether evolution is progressive or not. Dawkins argues that organisms evolve in a progressive direction, and Gould argues that evolution has no tendency.
Dawkins argues that evolution is progressive because there are so many different kinds of plants and animals now compared to 3.5 billion years ago when only bacteria existed. This is because life today is far more complex than bacteria. Gould, on the other hand, argued that evolution has not been progressive because, while the diversity of life has increased, it has not increased in complexity. To illustrate this point, he proposed the “drunkard model”. In this model, a drunken person moving away from a wall at a similar ratio of left to right appears to be moving away from the wall. In fact, the drunkard does not have any direction, but appears to be moving away from the wall, just as evolution appears to be moving in the direction of progress against the wall of bacteria.
In response to these contradictory arguments, a student in my science and writing class last year defended Dawkins’s argument. He proposed a new concept of progress in the evolution of life: “an increase in the number of cells, which increases the number of functions that an organism can perform, and therefore increases its complexity. The student then provided evidence for this, which was inconsistent with the claim, and even inconsistent with Dawkins’ position.
The first example he gives is the leg of a worm. The worms originally had legs, but when they became parasitic on humans, they didn’t need them and their legs degenerated. However, the student argued that this was not a degeneration because it gained the ability to regenerate instead. Similarly, in humans, the appendix degenerated and became an unnecessary organ, but the student argued that the body’s structure increased complexity because many organs work in pairs to perform efficient functions.
This student is mistaken in thinking that there is a connection between the loss of the worm’s legs and the worm’s ability to regenerate. The worm’s legs and its ability to regenerate are two separate things that evolved because as the environment changed, the legs became unnecessary and the ability to regenerate became necessary. If the worm were to be placed in an environment where it still needed legs, it would evolve to have legs without changing its ability to regenerate. Humans are similar. The fact that our organs are paired in pairs has evolved to make them more efficient, not because our appendix has degenerated. The author’s argument that the worms and humans evolved more complex forms to compensate for their degenerated organs is not convincing.
Next, the student argued that the ability of organisms to evolve is itself progress. If we go back to the model of the drinker from above, we can think of the wall that was blocking the drinker as moving. Starting with the simplest first life form, bacteria, the emergence of prokaryotes, eukaryotes, multicellular organisms, and humans is the evolution of the ability to evolve, which is strictly progressive.
But even if we accept both the evolution of the ability to evolve and the “moving wall model”, evolution is not evidence of progress. That life has a direction in its evolution can be explained by the above arguments. However, it would not be possible to claim that evolved life is progressive by any measure. This student’s assertion that complexity alone is the direction of evolutionary progress shows a lack of understanding of the complexity graphs in the book and McShay’s “controlled trend” and “passive trend” graphs. In the complexity graph, humans are tiny, tiny, tiny at the end of the graph, and bacteria are bigger than all the rest of life combined. Therefore, the rest of life can be seen as having evolved from the bacterial form only by chance. This can be analogized to the drunkard model of progressive regression, with a small probability of moving to the other side of the wall. So in order to make the claim that evolution is progress, you need to provide evidence other than complexity.
Both this student’s and Dawkins’ ideas are refutable by Gould’s arguments. If I were to provide further evidence in favor of Gould’s argument, I would point to the evolution of institutions in response to environmental changes mentioned above. The environment is constantly changing, albeit slowly, as evidenced by the repeated ice ages and thawing periods of the past. Organisms will adapt to these changes, which can be either progressive or regressive. For example, if we were to move to an environment where we constantly hear very loud sounds, our ears would degenerate. This could be considered regressive in terms of complexity. However, in the same environment, the ear could evolve further to hear both loud and soft sounds, and the vocal cords could develop further, resulting in a louder voice. In this way, it cannot be argued that evolution is moving in the direction of progress in terms of complexity. Therefore, Dawkins would need more evidence to support his claim that life is progressing.