His book On the Origin of Species (1859) did two things. First, it provided a great deal of evidence that evolution has taken place. Second, it proposed a theory to explain how evolution works. That theory is natural selection. Evolution and natural selection is the key to understanding and the diversity of life on Earth.
Voyage of the HMS BeagleEdit
Darwin spent almost five years on board a Royal Navy exploring ship, the HMS Beagle. He was the guest naturalist, which meant that he was responsible for making collections and notes about the animals, plants, and the geology of the countries they visited. The ship's crew made charts of all the coastal areas, which could be used by the navy wherever it went in the world. At the time, Britain had by far the largest navy in the world, and an empire which was global.
Darwin collected everywhere the ship landed. He found huge fossils of recently extinct mammals, experienced an earthquake in Chile, and noticed the land had been raised. He knew of raised beaches elsewhere, high in the Andes, with fossil seashells and trees which had once grown on a sandy beach. Obviously the earth was constantly changing, with land rising in some places, and sinking in others. He collected birds and insects, and sent shipments back to Cambridge for experts to identify.
Darwin was the first dedicated naturalist to visit the Galapagos Islands, off the west coast of Ecuador. He noticed that some of the birds were like mockingbirds on the mainland, but different enough to be placed in separate species. He began to wonder how so many new species came to be on these islands.
When Darwin got back to England, he edited a series of scientific reviews of the voyage, and wrote a personal journal which we know as The Voyage of the Beagle. It is one of the great natural history travel diaries.
In 1843 Darwin, who already had two children with his wife Emma, bought Down House in the village of Downe, Kent. He lived there for the rest of his life, and today the house and contents are open to the public.
While on the H.M.S. Beagle, and later back home in London, Darwin had come across the ideas of the Rev. T.R. Malthus. Malthus had realised that, although humans could double their population every 25 years, it did not happen in practice. He thought the reason was that a struggle for existence (or resources) limited their numbers. If numbers increased, then famine, wars and diseases caused more deaths. Darwin, who knew that all living things could, in principle, increase their numbers, began to think about why some survived, while others did not.p264-268 His answer took years to develop.
The theory of evolution says that all living things on Earth, including plants, animals and microbes, come from a common ancestor by slowly changing throughout the generations. Darwin suggested that the way living things changed over time is through natural selection. This is the better survival and reproduction of those that best fit their environment. Fitting into the place where you live is called adapting. Those who fit best into the place where they live, the best adapted, have the best chance to survive and breed. Those who are less well-adapted tend not to survive. If they do not survive well enough to raise young, this means they do not pass on their genes. In this way, the species gradually changes.
The first chapter of the Origin deals with domesticated animals, such as cattle and dogs. Darwin reminded readers of the huge changes mankind had made in its domestic animals, which were once wild species. The changes were brought about by selective breeding – choosing animals with desirable characters to breed from. This had been done generation after generation, until our modern breeds were produced. Perhaps what man had done deliberately, might happen in nature, where some would leave more offspring than others.
Darwin noticed that although young plants or animals are very similar to their parents, no two are exactly the same and there is always a range of shape, size, colour, and so on. Some of these differences the plant or animal may have got from their own ancestors, but some are new and caused by mutations. When such differences made an organism more able to live in the wild, it would have a better chance to survive, and would pass on its genes to its offspring, and they to their offspring. Any difference that would cause the plant or animal to have less of a chance to live would be less likely to be passed on, and would eventually die out altogether. In this way groups of similar plants or animals (called species) slowly change in shape and form so that they can live more successfully and have more offspring who will survive them. So, natural selection had similarities to selective breeding, except that it would happen by itself, over a much longer time.
He first started thinking about this in 1838, but it took a full twenty years before his ideas became public. By 1844 he was able to write a draft of the main ideas in his notebook. Historians think that he did not talk about his theory because he was afraid of public criticism. He knew his theory, which did not discuss religion, raised questions about the literal truth of the Book of Genesis. Whatever the reason, he did not publish his theory in a book until 1859. In 1858 he heard that another biologist, Alfred Russel Wallace, had the same ideas about natural selection. Darwin and Wallace's ideas were first published in the Journal of the Linnaean Society in London, 1858. Then, Darwin published his book the next year. The name of the book was On the Origin of Species by means of Natural Selection, or the preservation of favoured races in the struggle for life. This is usually called The Origin of Species.
Darwin wrote a number of other books, most of which are also very important.
- 1838-43: Zoology of the voyage of H.M.S. Beagle: published between 1839 and 1843 in five Parts (and nineteen numbers) by various authors, edited and superintended by Charles Darwin, who contributed sections to two of the Parts:
- 1838: Part 1 No. 1 Fossil Mammalia, by Richard Owen (Preface and Geological introduction by Darwin)
- 1838: Part 2 No. 1 Mammalia, by George Robert Waterhouse (Geographical introduction and A notice of their habits and ranges by Darwin)
- 1839: Journal and remarks (the Voyage of the Beagle)
- 1842: The structure and distribution of Coral Reefs
- 1844: Geological observations of volcanic islands
- 1846: Geological observations on South America
- 1849: Geology from A manual of scientific enquiry; prepared for the use of Her Majesty's Navy: and adapted for travellers in general. ed. John Herschel.
- 1851: A Monograph of the Sub-class Cirripedia, with figures of all the species. The Lepadidae; or, Pedunculated Cirripedes. Living barnacles.
- 1854: A Monograph of the Sub-class Cirripedia, with figures of all the species. The Balanidae (or Sessile Cirripedes); the Verrucidae, etc.
- 1851: A Monograph on the Fossil Lepadidae, or, Pedunculated Cirripedes of Great Britain. Fossil barnacles.
- 1854: A Monograph on the Fossil Balanidæ and Verrucidæ of Great Britain
- 1859: On the Origin of Species by means of natural selection, or the preservation of favoured races in the struggle for life
- 1862: On the various contrivances by which British and foreign Orchids are fertilised by insects (Fertilisation of orchids)
- 1865: On the movements and habits of climbing plants (Linnean Society paper, published in book form in 1875)
- 1868: The variation of animals and plants under domestication
- 1871: The Descent of Man, and selection in relation to sex
- 1872: The expression of emotions in Man and animals
- 1875: Insectivorous plants
- 1876: The effects of cross and self fertilisation in the vegetable kingdom
- 1877: The different forms of flowers on plants of the same species
- 1880: The power of movement in plants
- 1881: The formation of vegetable mould through the action of worms.
- "Charles Darwin (1809 - 1882)". BBC. Retrieved 2011-11-03.
- Darwin, Charles (annotated by James T. Costa). 2009. The annotated Origin: a facsimile of the first edition of On the Origin of Species. Harvard, Cambridge, Mass.
- Browne, Janet 1995. Charles Darwin: vol. 1 Voyaging, Part 2 The Travellor. Cape, London. ISBN 1-84413-314-1
- Browne, Janet 1995. Charles Darwin: vol. 1 Voyaging. Cape, London. ISBN 1-84413-314-1
- Desmond A. & Moore J. Darwin. 1991. Joseph, London.
- Bowler, Peter J. 2009. Evolution: the history of an idea. 4th ed, University of California Press.
- Palca, Joe (2009). "Darwin's theory: too big to publish : NPR". npr.org.
- Browne, Janet 2002. Charles Darwin: vol. 2 The power of place. Cape, London. ISBN 0-7126-6837-3
- Desmond, Adrian and Moore, James 1991. Darwin. Joseph, London. ISBN 0-7181-3430-3