What is Charles Darwin's theory of evolution and what inspired his revolutionary ideas

160 years ago, the British naturalist Charles Darwin published the book “The Origin of Species'” (1859) and radically changed biology with his Theory of Evolution.

His explanation of the origin of the human being represented a real revolution - since, until the mid-19th century, most Western scientists shared the idea that God had conceived all the creatures on the planet.

Some researchers were already talking about a possible evolution of species, but Darwin was the first to offer scientific evidence and explain the mechanism that makes it possible: natural selection.

Because of this, he became one of the most important thinkers and scientists in history. But first, he had to embark on an extraordinary journey across five continents, do hundreds of experiments and refine his ideas over 20 years.

It all started in 1831, when the then 22-year-old student at the University of Cambridge, UK, was invited to join a major expedition as a naturalist.

He spent nearly five years aboard the HMS Beagle, traveling across several continents, starting with South America. From there, he returned with dozens of specimens of live species, illustrations and fossils.

Fossils gave him one of the first clues to evolution—when he came across the remains of a mylodon, a now-extinct giant sloth-like animal, he deduced that the resemblance couldn't be mere coincidence.

When passing through the Galapagos archipelago, in the Pacific Ocean, the naturalist observed that on each island there were different species of turtles, which differed by the size of the neck and the shape of the cases.

After years of study, he came to the conclusion that the differences in the tortoises he saw on the Galapagos were a product of evolution.

According to his theory, there is a struggle for survival in nature, but the one who survives is not necessarily the strongest, but the one that best adapts to the conditions of the environment in which he lives.

In the arid environment, long-necked turtles would reach the bushes to feed. While those that lived in a humid place could eat grass and protect themselves from predators thanks to their short neck and rounded carapace.

Scientific advances came to prove Darwin's theory, and even the Catholic Church ended up accepting it decades later, with the due reservations that evolution was compatible with faith.