The Chicken or the Egg of Darwinism?

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David Rabadà

Our ancestors did not survive by fighting like Stallone; quite the contrary. The so-called law of the strongest now seems an overly militaristic assumption when applied to evolution. Combat involves risks, injuries, and losses. For this reason, many species on our planet avoid confrontation for obvious reasons. Our forebears, as part of Earth’s biology, also curbed their aggression to survive longer. The evolutionary success of our relatives was not thanks to Mazinger Z or Rambo. Their abilities, which allowed them to pass on their genetic legacy to us, lay elsewhere. The true engine of evolution was not brute strength or interspecies struggle, as some social Darwinists assert, but rather a different capacity: their rate of reproduction. To delve into this point, we must pause and reconsider Natural Selection and its most fragile aspect—its flaw: who survives.

Darwin was a pioneer, breaking away from the creationist biases of his era. His concept of Natural Selection emerged in a Victorian society largely rooted in Aristotelian fixism. At the time, the dominant worldview held that everything had remained more or less unchanged over time. This is not to say there were no doubts or evidence of drastic changes, but these were typically framed in terms of biblical cataclysms. The Great Flood or divine punishments provided the prevailing explanations. Confronted with biological evolution and the transformation of species, Darwin offered an explanation—one among many to come. Thus, in 1859, and after much deliberation, he published On the Origin of Species and introduced his theory of Natural Selection.

By 1930, with Natural Selection enriched by Mendelian genetics, palaeontology, and systematics, a broader theory arose: Neo-Darwinism. This extended framework described additional mechanisms, beyond Natural Selection, to explain changes within species and their variations. Later, in the mid-twentieth century, other disciplines converged to build the Modern Synthesis of Evolutionary Theory. This synthesis provided more nuanced and robust explanations of how new species evolve. It is important to stress that Darwin proposed only the initial mechanism—Natural Selection—while the subsequent developments came later. Today, numerous verified mechanisms account for the evolution of organisms. All of these, including Natural Selection, have shown that evolution has not always been a slow, gradual process between species; at times, it has involved sudden shifts. There is ample evidence of this in human evolution. But let us return to Natural Selection and its core weakness.

The process of Natural Selection rests on three observations Darwin made. First, species exert enormous effort to reproduce, producing thousands of seeds and sperm cells. Second, the variability within species is so broad that some individuals withstand the test of time while others do not. Third, very few offspring actually survive to reproduce. From these facts, Darwin concluded that, over time, only certain varieties—not all—manage to persist, as if selected in some kind of lottery without a guiding hand. For Darwin, survival belonged to the fittest, though this carried a circular logic that he never fully resolved. This was the flaw and the weak link in Natural Selection, though not in the Modern Synthesis of Evolution. If the fittest survive, and those who survive are deemed the fittest, we face a tautological argument—what philosophy terms a circular fallacy. It echoes the timeless questions: Which came first, the chicken or the egg? Or, what lies beyond the North Pole? The South Pole. And beyond the South Pole? The North.

All these questions share a common fault—they are poorly framed. The only way to break free from such circular reasoning is to clearly define the terms involved, scrutinise the events, and reframe the question. North and south are part of the same planet, so the correct inquiry would concern the Earth’s geometry that allows one to travel from north to south and back again. Chicken and egg belong to the same species, so the more accurate question would be: What was the first organism to reproduce via eggs? Likewise, survival and fitness are interlinked, so the right question is: Why do some organisms endure while others vanish? The answer is that endurance does not solely depend on superior adaptation, heightened aggression, or struggle, but simply on reproductive success. The higher the reproductive rate, the greater the chance of survival. Therefore, the issue is not about being fit or unfit, but about who, whether through adaptation or not, manages to last longer in an ecosystem. Ultimately, those who reproduce most effectively secure their continuity. This explains why many traits in our evolutionary history may not have been adaptations in themselves but were part of lineages that reproduced more successfully. Vestigial organs bear witness to this, but bipedalism, encephalisation, and abstract thought can also, in part, be seen within these categories.

Returning to Darwinism and the prejudices that have surrounded it, one might wonder why Natural Selection and its subsequent extensions took so long to gain acceptance. There are two main reasons. The first is the cultural legacy of Aristotelian fixism that permeated Western thought for centuries. The second is our biological heritage: primates, including humans, have an ingrained aversion to change due to an instinctive craving for security. Indeed, humans tend to favour the familiar and inherited over the novel and uncertain. History offers countless examples of this resistance. Copernicus defended heliocentrism with evidence in the sixteenth century, but it was not cautiously accepted until the seventeenth. Giordano Bruno posited the idea of an infinite universe, also in the sixteenth century, but it was not seriously debated until the twentieth. And, finally, Darwinism emerged in the nineteenth century, yet even today, some continue to reject it. Humans are, emotionally speaking, conservative because of our quest for security.

At this point, we can return to human evolution and observe that it is marked by leaps, with or without adaptations, clearly reflecting a pattern of mosaic evolution. Three of these leaps are crucial and serve as the backbone of this book. The first was bipedalism, over three million years ago. The second was the expansion of brain size, prior to two million years ago. And the third was the emergence of sophisticated thought, roughly half a million years ago. To these three milestones, we must add other key changes: the extension of an opposable thumb, the shortening of arms in favour of longer legs, the crafting of stone tools, the reduction of sexual dimorphism, the disappearance of oestrus in females, the expansion of sweat glands, the loss of body hair, the decline of instinctive aggression, and the development of articulated language, among many other traits.

Source: educational EVIDENCE

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