What Is Natural Selection?

· July 31, 2018

We have all studied or at least heard about Darwin’s Theory of Evolution. But do we really understand what evolution means? If we ask the majority of the population about evolution, we will probably encounter answers like, “That’s the theory that says humans come from monkeys”, “It’s the survival of the fittest”, “Natural selection is for animals and technology allows us to avoid it”, or “Evolution is when species increasingly adapt or develop”.

The statements above are loaded with errors that show us that few people really understand natural selection in depth. The central idea of Darwinism is that the species that adapt to their environment survive, and those that don’t disappear. But what does “adapt” means? It refers to the ability of a species in a particular ecosystem to reproduce and ensure the survival of its offspring.

Many myths and errors have arisen from the misinterpretation of this central idea. In this article, we’ll review the most common ones. We’ll talk about and contrast: (a) natural selection as a linear process, (b) the differential adaptation of species, and (c) natural selection as a struggle against everything.

natural selection


Natural selection as a linear process

One of the most recurrent misunderstandings is seeing Darwinism as a linear development of a species, as if species change generation to generation. Evolution doesn’t work this way. This error can derive from teaching the evolution of man as a succession of different hominids.

When it comes to understanding natural selection, the metaphor of a sieve is more appropriate. Many rocks are thrown into that screen, but only those with the right shape are selected. The rest are discarded. And then, with time, these rocks and other new ones are thrown into another sieve, where they’re selected again. And, in this way, in a sifted continuum, some rocks stay longer and others disappear.

Human beings, together with all other living beings, play the role of those rocks selected by the sieve. Those living beings that don’t adapt to the changing context will disappear or will have to change their environment. And in the course of this process, the species mutate and change. An important nuance is the fact that the context varies with time. A species or individual that adapted in the past may not adapt in the future, and vice versa.

The differential adaptation of a species

One of the most widespread and misconceived ideas are: “The human being is the best-adapted animal on Earth” and “We’re at the top of the evolutionary pyramid”. If we look at the definition of adaptation, we’ll see that it consists of surviving and having offspring that survive. In short, adaptation means maintaining the existence of the species. In addition, we can deduce that all species that currently exist have also adapted. This is because you either exist or you don’t exist.

Given this, many will allude to the great achievements of human beings or their high intellectual capacity in order to differentiate them from other living things. Just as the cat used its claws to survive, human beings used their intellect. Each species has different qualities that allow them to survive.

It’s true that human beings have build complex societies in order to achieve this, whereas a bacterium simply does so with its resistance and high reproductive capacity. However, we can think of human beings as students who are struggling to pass a class, whereas bacteria are the students who study on the day of the test and pass. In the end, the result is the same for both.

Darwin's natural selection

Natural selection as a struggle against all

Finally, we will talk about the myth of seeing natural selection as a struggle for existence or as the survival of the fittest. Don’t forget that those who survive are those who adapt to their environment. If the context favors those who attack, they will survive. But if the context favors those who flee, they will be the adapted ones.

Hobbes said that “Man is wolf to man”. He believed that human beings are ruthless and selfish by nature, competing with other humans. However, it’s only necessary to review the principles of natural selection and observe nature to understand that this is meaningless. Human beings and the vast majority of species have been able to survive thanks to their mutual support.

The ability to live in collaborative societies or herds allows for a better response to environmental challenges. However, this doesn’t mean that violence and competition don’t exist. In many situations, this has been shown as an adaptive behavior. But we must bear in mind that fighting isn’t the protagonist of natural selection. Simply, both struggle and mutual support are part of the species’ repertoire for facing their environment and the difficulties it can pose.