Born in 1809, Abraham Lincoln and Charles Darwin changed the world with the emancipation of black slaves and the theory of evolution, respectively. Darwin’s theory of evolution, in particular, shook the Christian-centered culture of the Western world, sparking a debate between adaptationists and anti-adaptationists. Steven Gould’s Discontinuous Equilibrium reconsiders the contingency of evolution and human supremacy in the midst of this debate, and offers a new direction for modern evolutionary theory.
The year 1809 marks the birth of two men who changed the world forever: Abraham Lincoln and Charles Darwin. If Lincoln freed black slaves from the West, Darwin freed man from God with his theory of evolution. That’s a bit of an exaggeration, of course, but when Darwin first proposed his theory of evolution, it had a huge impact because the Western world had been largely Christianized. The theory that humans evolved from primates like monkeys, rather than being created by God, shook the very foundations of Western life. The seemingly incompatible theories of evolution and creationism have, thankfully, found a happy medium in modern times.
Ever since Darwin introduced the mechanism of “natural selection” in The Origin of Species, there has been a great deal of debate about the power of natural selection. Those who believe in the power of natural selection are called “adaptationists” and those who doubt its power are called “anti-adaptationists”. In Darwin’s Table, these two groups of researchers argue their theories in a debate. Because the adaptationists have gained so much support in the last 30 years, their arguments can sometimes come across as a bit stilted and with a sense of authority from vested interests. I’d like to defend the anti-adaptationist position, which I think is well-represented.
One of the most prominent anti-adaptationists is Stephen Gould, a paleontologist at Harvard University. His arguments against Darwin and adaptationists can be summarized in three main ways.
The first is “punctuated equilibrium theory,” which holds that evolution can happen abruptly. This is different from Richard Dawkins’ “gradualism,” which holds that evolution happens slowly and steadily. To put it simply, gradualism is like a 100-meter run, while punctuated equilibrium is like a long jump with varying tempos.
The second is that we can’t assume that “evolution is progress”. The evolution of life, starting with the simplest organisms like bacteria, inevitably evolves into more and more complex organisms over time, but it’s hard to see this as true progress. In fact, even Darwin was wary of the idea of evolution as progress in The Origin of Species. However, later evolutionists sought to establish humans as the most advanced, and this soon became successful, justifying many of our destructive behaviors.
Third, it is argued that the evolution of life is highly dependent on chance. If an asteroid had not hit the Earth 65 million years ago, he argues, the reigning dinosaurs would not have become extinct, and the age of mammals would not have begun. In this context, he says, “Rewind the tape of Earth’s history and play it again. There would be nothing like us, and a completely different group of organisms would have emerged.”
So far, we’ve covered Gould’s main arguments. Now, I’d like to focus on the theory of punctuated equilibrium. As I explained earlier, stochastic equilibrium is an evolutionary theory that states that the evolution of species that reproduce by sexual reproduction is characterized by periods of steady state, where there is no significant change for most of the time, and periods of speciation, where there is rapid speciation in a relatively short period of time. This is different from Dawkins’ theory of phylogenetic gradualism.
“Dawkins advocates gradualism. Speciation is when a small population is geographically isolated, and as it reproduces, it evolves into individuals with traits that are completely different from the population. This theory supports the theory of punctuated equilibrium, which states that evolution happened abruptly. Dawkins presents fossils that show trilobites have undergone a gradual evolutionary process, arguing that slow evolution is possible as well as abrupt evolution.”
This claim is very wrong. Trilobites have survived on Earth for over 200 million years, and the trilobite fossils found today have the same structure and shape regardless of age. This lack of evolution over 200 million years cannot be explained by phylogenetic gradualism. This trend is not unique to trilobite fossils. If evolution were gradual, we would expect to find intermediate forms between one species and the evolved species. However, when we study fossils from different strata, we find that the organisms have not changed at all. Furthermore, there are many species that are called living fossils and have survived for tens or hundreds of millions of years without evolving, such as the silurcans, horseshoe crabs, parrot shells, New Zealand wedge lizards, and ginkgo trees. Darwin was aware of this fact, but he diligently dismissed it, citing the incompleteness of the fossil record.
In Gould’s book After Darwin, he argues in favor of a theory of punctuated equilibrium called shrubbery theory. We learn about human evolution in elementary school. We learn the three stages of human evolution in elementary school: Australopithecus africanus ⟶ Homo erectus ⟶ Homo sapiens. This was accepted as orthodoxy until new species were discovered in the 1930s and 1970s, called Australopithecus robustus and Homo habilis, respectively. The two new species differed greatly from Australopithecus africanus in their upright posture and brain capacity, but they were similar in age. In fact, Homo habilis had twice the brain capacity of Australopithecus africanus, and now has two-thirds of the brain capacity of an adult. Furthermore, none of these three showed any significant evolutionary propensity while they were alive, meaning that we, as Homo sapiens, are not the preordained final masterpiece on the evolutionary ladder, but rather a branch that, through countless prunings, has managed to grow properly on the evolutionary shrub.
Some might criticize this argument, saying “Don’t you think there are intermediate species where evolution happens gradually and they just haven’t been fossilized, or maybe we just haven’t found them yet, so give us some more scientific evidence.”
If this criticism is raised, I think they would have to admit that there are many theories that are based on fossil evidence, so their theories are also uncertain. In fact, this criticism was not well answered in the past, but with the development of evolutionary developmental biology, also known as evodibo, conclusive evidence is being found to answer it. In studying fruit flies, developmental geneticists have found that many mutations, such as the antennapedia mutation, in which the legs are attached to the head, are caused by problems with just one specific gene, called the homeotic gene (Hawkes gene), meaning that a single gene can cause the entire body to look completely different. Not only that, but they found that homeoboxes (collections of homeotic genes) have been found in organisms ranging from nematodes to elephants to humans, and even found that they have very similar sequences. Specific examples include the eyeless gene in fruit flies, the aniridia gene in humans, and the small eye gene in mice. Each of these three genes regulates the development of the eye, but when the mouse small eye gene was put into the fruit fly, it induced eye tissue in the fruit fly, not in the mouse. In another example, the Distalis gene, which causes mutations on the outside of the fruit fly’s legs, is used to make appendages in all living things, and the Tinman gene, which is essential for heart formation in fruit flies, was found to be important for heart formation in vertebrates. It’s no wonder that humans and orangutans have only 0.1% genetic differences, yet they evolved into two very different species. But what regulates these genes? When they are activated by external environmental stimuli, changes are made to the genetic toolkit (all the genes responsible for animal development, including the homeotic genes) and individuals undergo abrupt changes.
The existence of the genetic toolkit and the on-off switches that control it, discovered in fossilized material without intermediate species and through advances in evolutionary developmental biology, is strong evidence in favor of Gould’s theory of punctuated equilibrium. As advocates of phylogenetic gradualism have been unable to counter this evidence, punctuated equilibrium has gained momentum. The significance of punctuated equilibrium theory is that it sees humans not as special beings at the top of the evolutionary ladder, but as creatures that have undergone the same process of mutation as all other living things. Science is supposed to be value-neutral. However, in its quest to place humans at the top of the heap, evolutionary theory has provided a legitimate basis for human supremacy, white supremacy, and the destructive behavior of humans and the enslavement of yellow and black people by whites. I hope that from now on, there will be more scholars like Steven Gould who will conduct objective research through empirical data and scientific analysis.
