Charles Darwin was an English naturalist who studied variation in plants, animals and fossils during a five-year voyage around the world in the 19th century. Darwin visited four continents on the ship HMS Beagle.
Darwin observed many organisms including giant tortoises, mocking birds, finches and other unusual animals during his five week visit to the Galapágos Islands, off the coast of Ecuador in the Pacific Ocean. He continued to work and develop his ideas for many years after he returned from his voyages.
Finally, as a result of Darwin's world expedition and observations, which were backed by many years of experimentation, his discussions with like-minded scientists and his developing knowledge of geology and fossils, he proposed the theory of evolution by natural selection.
Darwin proposed that:
This theory is called natural selection.
Darwin's ideas were documented in the book On the Origin of Species, which was published in 1859. The naturalist's ideas created controversy in Victorian society.
Darwin's theory of evolution challenged the idea that God made all the animals and plants that live on Earth, which contradicted the commonly held Christian views of his era. He did not publish his scientific work and ideas until 28 years after his voyage.
The theory of evolution through the process of natural selection was only gradually accepted because:
Some scientists were reluctant to change their minds about the ideas of creationism, even when new evidence was discovered that contradicted their ideas.
Darwin's book, On the Origin of Species, was a world best-seller and is still in print today. With every new edition of his book, more evidence was discovered to support Darwin's ideas. This led to the development of his theory over time.