Gould’s theory of discontinuous equilibrium argues that evolution does not occur gradually, but rather that new species emerge through abrupt changes, and suggests that humans are not the end goal of evolution. It emphasizes that evolution has no progressive direction and proceeds unpredictably by chance.
Throughout history, newly discovered scientific facts have surprised and sometimes disrupted the world. Darwin’s theory of evolution is one of the most prominent examples. More than 150 years later, it’s still a hotly debated topic among biologists, each with their own theories. Before we get into the nitty gritty, let’s take a quick look at some of the theories.
First, the orthodox Darwinian theory holds that evolution is gradual, with individuals that are more adapted to their environment and beneficial for survival and reproduction being naturally selected, and that favorable traits accumulate over time, leading to the gradual evolution of living things. However, the orthodox Darwinian theory fails to explain the incompleteness, or “missing link,” of the lack of fossils of intermediate species in the evolutionary process. Neo-Darwinism is a complementary theory. Neo-Darwinism theorizes that intermediate species are statistically unlikely to be fossilized because they do not create stable populations, and therefore are not found. The other theory is orthodox adaptationist Darwinism, advocated by renowned evolutionist Richard Dawkins, which attempts to understand everything in nature as a direct result of natural selection and adaptation.
Stephen Jay Gould, a prominent evolutionist like Dawkins, has proposed a theory that breaks the common sense of the above theories: punctuated equilibrium. The theory explains that the reason why we don’t find fossilized forms of intermediate species is because there are no intermediate species at all. In other words, evolution is not a gradual progression from one species to another, but rather a sudden (abrupt) change from one species to another. As someone who was introduced to the theory of evolution as a child and had no problem accepting the theory of natural selection, the idea of punctuated equilibrium was refreshing. To explore Gould’s argument in more depth, I’m going to read his classic book ‘ Full House ‘ and explore its content.
People often say that humans are the most unique and most advanced creatures that have ever walked the earth. I used to think this was true until I came across this book. Our unique consciousness allows us to speak and think in language, organize societies with rules, and live uniquely. But is being special really the same as being the most advanced? After reading this book, my answer is no. We humans are just a tiny branch on the tree of life, the latest to appear since life began to appear on Earth. But because we have a special consciousness, we are arrogant enough to try to interpret the great tree of life based on that tiny branch, and we make the mistake of interpreting the evolution of life as occurring in a progression that ultimately tends toward humans.
Gould argues that evolution does not occur by progression, and that the very idea that it tends to occur in a certain direction is a fallacy. In other words, evolution is the result of unpredictable, directionless chance. As I mentioned earlier, I used to think that humans were the end goal of evolution and the most advanced organisms until I read this book. But now, I completely agree with Gould.
Recently, the coronavirus has been spreading fear around the world that it is the end of the world. It’s not the only disease caused by viruses; there are many others, including the swine flu pandemic of a few years ago, Ebola, SARS, and more. We don’t know exactly when viruses first appeared on Earth, but one thing is certain: they predate humans. If evolution is about progress, it doesn’t explain how more genetically advanced humans can suffer and even die from more degenerate viruses. It also doesn’t explain why the most advanced forms of humans are not the most abundant organisms on Earth. Since these questions are not explained by the theory of evolution by progression, I also believe that evolution is not by progression, and I believe that we must avoid making this error in order to truly understand Darwin’s theory.
However, while Gould’s main theory, the discontinuous equilibrium theory, has provided a new direction in the interpretation of evolutionary theory, I do not think it provides a 100% explanation of evolution. Here are my thoughts on the discontinuous equilibrium theory.
Gould’s interrupted equilibrium theory, as described in the previous section, is a theory that states that the evolution of species of organisms that reproduce sexually is characterized by periods of steady-state, where there is little change for most of the time, and periods of divergence, where there is rapid speciation in a relatively short period of time, which directly refutes the traditional theory of phylogenetic progression, which states that evolution occurs gradually over generations over very long periods of time. Let’s take the horse species Mesohippus and Myohippus, which Gould uses as an example in his book. The conventional theory of phylogenetic progression states that the evolution from Mesohippus to Myohippus was gradual and continuous. However, Gould proposed an interrupted equilibrium theory, in which the fossilized foot bones of the two species are clearly distinguishable, and evolutionary change occurs at the point where the branches diverge, as the two species coexist for a long time and tend to appear suddenly in geologic time and then remain unchanged for long periods of time. Gould argues that evolution is driven by the unpredictability and chance of the divergent periods, when species speciation occurs.
But this raises a question. If evolution is not as gradual as Gould suggests, but rather suddenly occurs due to the randomness of mutations, then the question arises as to how to scientifically explain the randomness. To be more specific, to use Gould’s example, the evolution of Mesohippus to Myohippus would mean that some mutation by chance caused the mother Mesohippus to give birth to the child Myohippus, which is not scientifically explained. To take an even more extreme example, punctuated equilibrium theory claims that the evolution from apes to Australopithecus, the ancestor of humans, happened all at once rather than gradually over time. Of course, while abrupt equilibrium does explain the absence of fossils of intermediate species that are not accounted for by conventional phylogenetic gradualism, it raises the question of how the missing link is explained, which is not entirely satisfactorily explained by chance, which is a very good weakness for creationists to attack evolutionary theory. I realize that this is a leap of faith, but I believe that evolutionary theory must be scientifically flawless in order to defeat creationism. As an engineering student, I look forward to the day when new studies and investigations will continue to be conducted and evolutionary theory will no longer be a theory but a law.
Although the book left me with questions, I agree with Gould’s theories overall and was particularly impressed with the idea that evolution is not a progression and that humans are not the most advanced organisms. Right now, humans are the very last branch on the tree of life, but in the distant future, perhaps even closer than we think, other non-human creatures will branch out further. No one knows what mutations will occur or what creatures will emerge. One thing is certain: life will continue to evolve.
