Charles Darwin was born in England on February 12, 1809. As a child, he was greatly influenced by his grandfather, Erasmus, on his theory of how organisms evolved over time. Then, shortly after finishing college, Charles set sail on the H.M.S. Beagle on a voyage around the world. During this voyage, he would collect plant and animal specimens and study them. He would write notes on these specimens and began to piece together the puzzle of evolution. But one stop really intrigued him, the Galapagos Islands. He was puzzled by the diversity of life on these islands. He observed 13 different types of finches, and all were different from the finches found on the mainland although he could tell they were related. From these studies, he came up with two main ideas. First, descent with modification, or evolution, and second, the mechanism of evolution, which is natural selection. Descent with modification is the theory that every living species descended with changes, from other species over time. Natural selection is the theory that only the organisms that are best fit to a certain environment survive. Although Darwin's voyage ended in 1836, he did not publish these findings until 1859 in his book "The Origin of the Species". He was publicly ridiculed, especially by the religious community, but the scientists were soon convinced. Charles Darwin went on to publish more books on his theory of evolution, and continued to prove his point. But he had a life troubled with sickness and he died on April 19, 1882.