↣ Darwin's expeditions and discoveries

Now I will explain you about the expeditions that Darwin made and the main contributions that he made to science.

The Beagle Expedition

On December 27, 1831, he sailed from Davenport with Darwin on board, ready to start what he called his “second life. Without knowing it, Darwin had risked rejection by Robert Fitrzoy already than the captain, estimated that the naturalist's nose did not reveal the energy and determination enough for the journey.

The objective of the expedition led by Captain Fitzroy was to complete the topographical study of the territories of Patagonia and the Tierra del Fuego, the layout of the coasts of Chile, Peru and some islands of the Pacific and the realization of a chain of chronometric measurements worldwide. 

The trip, which lasted almost five years, led to Darwin along the coasts of South America, only to return later during the last year visiting the Galapagos Islands, Tahiti, New Zealand, Australia, Mauritius and South Africa.

During this period Darwin's mood underwent a profound change transformation. He began his passion for the scientific aspects of his activity.

The study of geology was, initially, the factor that most helped turn the voyage into Darwin's true education as a researcher, since with him the need to reason. Darwin took with him the first volume of the Principles of Geology by Charles Lyell, author of the so-called theory of current causes; visited (Santiago Island, Cape Verde), Darwin he was convinced of the superiority of the approach advocated by Lyell.

In Santiago he had for the first time the idea that the white rocks that observed had been produced by molten lava from ancient volcanic eruptions, which, sliding to the bottom of the sea, would have dragged crushed shells and corals communicating to them rocky consistency.

Toward the end of the voyage, Darwin learned that Adam Sedgwick had expressed to his father the opinion that the young man would become a important scientist; the correct prognosis was the result of the reading by Reverend Henslow, before the Philosophical Society of Cambridge, from some of the letters sent by Darwin.

Among the scientific achievements obtained by Darwin during the trip, the first to see the light (1842) would be the theory on the formation of coral reefs by growth of coral on the edges and on top of islands that were slowly sinking. Along with this hypothesis and establishment of the geological structure of some islands such as Santa Elena, it is necessary to highlight the discovery of the existence of a certain resemblance between the fauna and flora of the Galapagos Islands with the of South America, as well as differences between the specimens of a same animal or plant collected on the different islands, which made him uspect that the theory of species stability could be put in question. 

It was the theoretical elaboration of these observations that, years later, it resulted in his statement of the evolutionary theses.

The results of the trip

In 1835, he was ill with an infection called Staphylococcus disease Chagas as a consequence of an insect bite.

Darwin returned to England in 1836. In any case, from his arrival until the beginning of 1839, Darwin lived the most active months of his life. He worked on writing his diary of the trip (published in 1839) and in the elaboration of two texts presenting their geological and zoological observations.

He installed in London from March 1837, he devoted himself to "doing a little society", acting as honorary secretary of the Geological Society and making contact with Charles Lyell.

In July 1837, he began to write his first notebook about his new views on the "transmutation of species", that were imposed on him when reflecting on his own observations on the classification, affinities, and instincts of animals, and also as a consequence of an exhaustive study of how much information was he able to collect regarding the transformations experienced by species of plants and domestic animals due to the intervention of breeders and horticulturists.

His investigations, carried out on the basis of "authentic principles Baconians", they soon convinced him that selection was the key to human success in obtaining useful improvements in the races of plants and animals. The possibility that this same selection acted on the organisms living in a state of nature became apparent to him when in October 1838 he read "as a pastime" the Essay on the principle of population of Thomas Malthus Great observer of the habits of animals and plants, and to perceive the la struggle for existence, it occurred to him that, under these circumstances, favorable variations would tend to be preserved, while the unfavorable would disappear, with the result of the formation of new species.

Darwin considered that, "at last, he had got a theory with which to work"; however, concerned to avoid prejudice, he decided refrain for a while from writing anything. In June 1842 it was allowed privately writing a summary on this subject, which he expanded to two hundred and thirty pages in the summer of the year 1844.

Darwin had married on January 29, 1839 with his cousin Emma Wedgwood.

In 1839 the couple's first child was born, and Darwin began a relationship with him series of observations, which lasted over the years, on the expression of emotions in man and animals.

From 1846 to 1854, Darwin was busy writing his monographs on cirripods, in which he had been interested during his stay on the coast of Chile when he found specimens of a type which raised classification problems. Those years of work served to make him a true naturalist according to the demands of his time, adding to the practical learning acquired during the trip the theoretical training necessary to address the problem of relationships

between natural history and taxonomy.

Furthermore, his studies on the barnacles earned him a solid reputation among specialists, being awarded in November 1853 by the Royal Society, of which Darwin had been a member since 1839.

The theory of evolution

Early in 1856, Darwin was advised to work on the complete development of his ideas about the evolution of species. Darwin then undertook the writing of a work that but when he was halfway through the job, his plans fell apart ruined by an event that precipitated events: in the summer

In 1858 he received a manuscript containing a brief but explicit exposition of a theory of evolution by natural selection, which exactly matched his own views. The text, forwarded from the island of Ternate, in the Moluccas, was the work of Alfred Russel Wallace a naturalist who since 1854 was in the archipelago Malay and that as early as 1856 he had sent Darwin an article on the appearance of new species.

Darwin briefed Lyell on the matter and communicated his hesitations about how to proceed with the publication of their own theories, coming to express their intention to destroy their own writings before appearing as an usurper of the rights from Wallace to priority.

Darwin summarized his manuscript, which was submitted by Lyell and Hooker before the Linnean Society on July 1, 1858, together with the work of Wallace and with an extract from a letter sent by Darwin on the 5th of September 1857 to the American botanist Asa Gray, in which contained an outline of his theory.

The origin of species

Darwin wrote the book On the Origin of Species by means of natural selection, or the preservation of favored races in the struggle for life, November 24, 1859. 

The theological implications of the work, which he attributed to the selection natural faculties hitherto reserved for the divinity, were cause immediately began to form a festerin opposition.

Darwin steered clear of direct intervention in the public controversy until 1871, when his work "The Origin of the man and selection in relation to sex", where he presented his arguments in favor of the thesis that man had appeared on Earth by exclusively natural means.

In 1872, with "The Expression of the Emotions in Man and Animals", seminal work of what would later become the modern study of behavior, Darwin put an end to his concerns about the theoretical problems and devoted the last ten years of his life to various research in the field of botany.

At the end of 1881 he began to suffer from serious heart problems, and He died of a heart attack on April 19, 1882.