Most people consider Charles Darwin to be the first to theorize evolution by natural selection. The idea that different species of animals evolve over millions of years was unheard of (almost) before Charles Darwin published On the Origin of Species in 1859.
Science philosopher Daniel Dennet called Darwin’s theory of evolution “the single best idea anyone has ever had”.
The idea that changed everything
Darwin’s basic idea was that animals look the way they do not by design, but because genetic variation gives certain animals different features, and certain features equip the animal to survive better in their habitat, and thus stay alive to pass on their genes. Those not equipped die off. It’s “survival of the fittest”. It was considered one of the great turning points in science, if not human thought itself.
Such a world-shattering concept caused quite an uproar, too, especially among Christians who believe that God designed all the animals to look the way they do.
But was Darwin the first person to have this idea?
In ancient Greece, philosopher Aristotle was making scientific observations about the natural world. He seemed to stumble upon a certain… idea.
Check out this line from Aristotle in his book, Physics, written in 350 B.C.:
So what hinders the different parts [of the body] from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to the other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity, and whatsoever things were not thus constituted, perished, and still perish.
That passage is more or less a very simple explanation of natural selection, written a whole 2,200 years before Darwin.
And Darwin even quoted Aristotle in On the Origin of Species. He says of Aristotle,
“We here see the principle of natural selection shadowed forth, but how little Aristotle fully comprehended the principle, is shown by his remarks on the formation of the teeth.”
Aristotle immediately discounts his idea in the passage that comes next in his writings. And Darwin obviously had a much more thorough and researched theory of evolution and deserves the credit. But this passage does show that Darwin was in fact not the first to think up the basics of the idea of evolution by natural selection.