@ozfd I am going to have a go at explaining - - it's been a while since I read the story of Darwin's ride on the 'Beagle' - he was away for over 2 years, sailing around the world visiting South America as well as Australia; the Galapagos Islands were of huge interest to him, as they were so remote from other lands and had such unusual animals only remotely related to creatures he had seen on land, but drew the conclusion, that they had adapted characteristic which were beneficial in their isolated situation.
He was probably the first person who talked about 'natural selection' and he meant by that that only those fit for a certain environment survive and breed - eventually producing a new species - that actual process of change is called 'evolution' - he had a different phrase for that, but used 'evolution' in his published work. He hesitated about publishing his book for many years, because he moved in conservative circles (and he had trained as a clergyman) and especially his wife was a deeply religious person, who would have seen his insights as blasphemy. Eventually he published "the Origin of Species" just in time to pip another scientist (Alfred Wallace) to the post, who had similar insights and who he was in contact with. there are still groups of people, particularly from fringe Christian sects who do not believe in the correctness of his theories, but they are widely accepted by naturalists and people who purpose-breed animals (cattle, birds, dogs) and who know from practical experience about the efficacy of 'selective breeding'.
