In this blog post, I’ll compare Dawkins’ and Gould’s views on evolution, focusing on ‘Darwin’s Table’, and examine the debate surrounding evolution and progress from Gould’s perspective.

Are “evolution” and “progress” the same thing?

“Evolution” and “progress.” If we look up the primary definitions of each in a dictionary, “evolution” is defined as “the gradual development of things or events,” while “progress” is defined as “an improvement or advancement in degree.” In fact, we often use these two words interchangeably in everyday life without making a clear distinction between them.
Ironically, however, the moment these two terms are brought into the realm of biology, they give rise to a sharp contrast. The question “Is evolution progress?” may seem like a difference of just a single character, but in biology, it signifies entirely different perspectives. Since Darwin published ‘On the Origin of Species’ in 1859, this issue has remained one of the oldest and most important debates in evolutionary biology.
On the fifth day of ‘Darwin’s Table’, which explores the fascinating topic of “Evolution and Progress,” the debate between the two camps—centered on Dawkins and Gould—is filled with sharp logic and fierce rebuttals.

Gould on Evolution: Diversity Increases, but It Is Not Progress

The Gould team’s argument is as follows: life has simply evolved in the direction of increasing diversity, and this increase in diversity should not be directly interpreted as a trend toward “progress.” The arguments supporting their position can be summarized into three main points.
First, in response to the Dawkins team’s claim that the evolution of life proceeds in the direction of increasing complexity, Gould presents the “Drunkard’s Walk” model. The Drunkard’s Walk model goes as follows. Suppose a heavily intoxicated man is staggering haphazardly. There is a wall to his left and a ditch to his right. In this scenario, it is highly likely that he will eventually fall into the ditch. This is because even if he moves to the left, he will be blocked by the wall and forced to move back to the right. Although the drunkard’s movements are random, from an outside perspective, it appears as if he is continuously moving to the right.
Gould explains that the evolution of life follows a similar pattern. Life began at the “simplest form”—the left wall—and the evolutionary direction of each lineage is fundamentally random. However, since life cannot become simpler than its minimum complexity, it ultimately appears as if complexity is increasing. In other words, progress is not a real phenomenon but an optical illusion.
Second, Gould argues that while it is true that the maximum complexity of organisms has increased compared to the past, this cannot be directly equated with progress. When comparing the frequency of organism emergence by era based on complexity, the distribution curve merely extends its right tail; the overall center does not shift significantly. Therefore, the value that best represents this distribution is not the maximum or the average, but the mode.
From this perspective, Gould argues that the left wall—representing the minimum complexity of life, namely bacteria—is the true representative of life. Bacteria have been the most abundant throughout the entire history of life, have appeared most frequently, and still occupy the center of the biosphere today. This fact is also why it is difficult to understand evolution as “progress” in the sense of a process in which “higher organisms emerge while lower organisms gradually disappear.”
Finally, Gould’s team emphasizes the importance of contingency. Unpredictable events, such as asteroid impacts, have fundamentally altered the history of life, and human existence itself is the result of the accumulation of such contingent events.

Why did Dawkins view evolution as progress?

In contrast, the view of Dawkins’ team—which argues that organisms have progressed through evolution—is as follows.
First, they point out that when comparing early life forms from approximately 3.5 to 4 billion years ago—when life first emerged—with today’s most complex organisms, the latter possess far more complex structures. Therefore, they view life as having evolved over the long term toward increasing complexity.
Furthermore, Dawkins points out that defining progress solely in terms of complexity remains an anthropocentric bias. He argues that a concept of progress that transcends anthropocentrism is entirely possible and proposes two criteria.
The first is to understand progress not as an increase in complexity or intelligence, but as a process of accumulating traits that allow for more effective adaptation to the environment. When the environment changes, organisms adapt and evolve over long periods of time in ways that favor survival and reproduction. Therefore, this process can be viewed as progress.
The second is the concept of “evolving capacity for evolution.” Dawkins views a series of events—from the first replicator to the emergence of prokaryotic cells, meiosis and sexual reproduction, eukaryotic cells, and multicellular organisms—as major turning points in evolution. He explains that these changes were irreversible innovations that greatly expanded the possibilities for subsequent evolution.
In this regard, Dawkins’ team directly critiques Gould’s “drunkard model.” They argue that whenever a major evolutionary milestone appears, it is as if the left wall of the drunkard model itself shifts to the right.

Why is Gould’s perspective still important?

In discussions surrounding evolution and progress, Gould’s arguments retain a persuasiveness that is difficult to overlook even today. I now intend to supplement the counterarguments against Dawkins’ team—which were not sufficiently addressed in ‘Darwin’s Table’—and to summarize Gould’s logic in greater detail.
First, it is necessary to examine Gould’s perspective and the significance of his theory. In fact, the most fundamental reason for the divergence between Gould’s and Dawkins’ views is that their perspectives themselves are different. While Gould views the evolutionary process of life diachronically within the context of its entire history, Dawkins tends to interpret outcomes by focusing on significant events and innovations that have emerged during the evolutionary process.
Over the past few decades, evolutionary biology has placed relatively more emphasis on the latter perspective. However, now that a sufficient body of evolutionary theory and empirical data has been accumulated, the task of synthesizing and reevaluating these has also become a critical challenge. This is because placing excessive emphasis on specific events or innovations risks losing sight of science’s original purpose: to consider the overall structure and distribution of the evolution of life as a whole.
Gould points out that this is precisely where Dawkins erred. He describes this as “as ridiculous as a small dog’s tail wagging a large body.”
There is no logical flaw in the graph presented by Gould, and the conclusions drawn from the comparisons across different time periods are also entirely valid. Based on this graph, for the claim that “evolution is progress” to hold true, the right tail of the graph must serve as the central axis guiding all of life. However, in reality, the organisms corresponding to the right tail are extremely few, and only a very small number of species belong to that region. Furthermore, even if the organisms located at the far right were arranged in chronological order, they would not constitute a single evolutionary lineage. Most of the species generally presented as stages of evolution—with the exception of a few cases, such as the transition from prokaryotes to eukaryotes—do not share a direct ancestor-descendant relationship.

Is Dawkins’ rebuttal truly valid?

Dawkins’ team argues that in Gould’s “drunkard model,” the left wall itself moves. Their basis for this is the “evolutionary watershed.” Dawkins explains that through these watersheds, life achieved “irreversible progressive innovations.”
It is difficult to argue that this claim itself is completely wrong. Indeed, the history of life has seen significant events that greatly expanded the possibilities for subsequent evolution. However, the term “irreversible” does not necessarily mean that life forms from earlier stages disappear, leaving only the new stage behind. I am not attempting to deny the existence of these turning points or to refute their irreversibility. I simply believe we must not overlook the fact that organisms that have evolved beyond these turning points into new stages represent only a tiny fraction of all life.
Ultimately, the fundamental left wall of the Drunkard Model remains fixed. The criterion of minimum complexity of life itself remains unchanged. Therefore, Dawkins’ claim that the left wall shifts to the right does not sufficiently refute Gould’s original model.

A Review of the Claim That “The Drunkard Is Stumbling on a Sloping Sidewalk”

In the essay “The Drunkard Is Stumbling on a Sloping Sidewalk,” included in the appendix, Bang Ki-seung argues that the sidewalk in Gould’s drunkard model is not flat but slopes toward a ditch. In other words, he contends that evolution is directional. Here, I intend to examine the problems with this claim.
First, Bang Ki-seung’s argument lacks sufficient evidence to support it. He himself adopts a somewhat cautious stance, using the phrasing that the sidewalk in the Drunkard Model “does not necessarily have to be flat; it could be sloped.” The claim that the sidewalk is sloped implies that evolution has a direction, and the evidence he presents for this is natural selection. The argument is that since natural selection favors advantageous traits, evolution possesses a certain directionality.
Even if we make a concession and accept this logic, the conditions for natural selection he presents are overly broad and general, making them unconvincing. It is difficult to conclude that a consistent directionality exists throughout biological evolution based solely on the fact that Earth has gravity, an atmosphere, oceans, and land.
In reality, it was far more specific and localized environments that influenced biological variation. In evolutionary biology, natural selection is always discussed in conjunction with environmental changes. If one emphasizes only the Earth’s universal environment without sufficiently considering diverse regional environments and environmental changes across different eras, it becomes difficult to explain the possibility that evolution can occur in various directions. An overly broad claim may sound plausible at first glance, but it lacks the specificity required for a scientific explanation.

Can reproduction alone explain Gould’s graph?

Another key argument in this essay is “reproduction.” Bang Ki-seung uses the example of “Noah’s Ark” to criticize the graph presented by Gould. To summarize his argument, he claims that even without evolution, the current distribution of organisms can be explained by reproduction alone.
However, it appears that Bang Ki-seung has not accurately understood the graph presented by Gould. The vertical axis of Gould’s complexity graph represents the frequency of occurrence of species, not the current population size of organisms on Earth. Therefore, it is not directly related to population size.
Nevertheless, it is inappropriate to attempt to explain the graph based on the fact that bacteria are the most abundant organisms on Earth because of their exceptional reproductive capacity. Even if we were to follow his logic and consider reproductive capacity, it is possible that bacteria would appear more frequently than humans across different time periods. However, it is more reasonable to view this not simply as a result of high reproductive capacity, but rather as a characteristic stemming from their low fundamental complexity and their persistent appearance across diverse lineages.
Therefore, the claim that Gould’s graph can be explained by reproductive capacity alone lacks sufficient evidence, and the logic used to criticize the “drunkard model” based on this argument is also difficult to sustain.

Reasons for Adopting Gould’s Position

While reading ‘Darwin’s Table’ and organizing my rebuttal to Bang Ki-seung’s essay, the reasons why I came to support Gould’s position became even clearer.
Dawkins’ theory may appear more dynamic and sophisticated than Gould’s. It also clearly has the advantage of effectively explaining innovative events in the history of life. However, Gould questioned the uncritical conventional wisdom that life is constantly progressing and guided us to view evolution from a macro perspective—that of the distribution and history of life as a whole.
In that regard, Gould was not merely a scholar who opposed existing claims for the sake of it, but a researcher with solid evidence to support his logic. Therefore, to me, Gould was, as the title suggests, someone who had “something to be trusted.”