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Darwin and the Gal á gapos. The Story of the Finches. Place of Birth, February 12, 1809. 1831.

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darwin and the gal gapos

Darwin and the Galágapos

The Story of the Finches

slide3
1831

Passes his BA examinations on 22 January without honours and remains at Cambridge for a further two terms to fulfill residence requirement. Spends much time with Henslow, and in August accompanies Adam Sedgwick, Professor of Geology, on his annual field trip to Wales. In August he returns to Shrewsbury from Wales to find a letter from Henslow inviting him to join the Beagle voyage. Darwin’s father objects, but his uncle, Josiah Wedgwood II, persuades him otherwise. Meets Captain Robert FitzRoy (1805-65) and makes preparations for the voyage.

professor stevens henslow
Professor Stevens Henslow

John Stevens Henslow, Professor of Botany at Cambridge. He passed on to Darwin the offer of the Beagle voyage and stored his collections until he returned to Cambridge in 1836.

the beagle 1837 darwin voyage narrative
The Beagle, 1837Darwin Voyage: Narrative

In 1831, Charles Darwin sailed to the Galapagos Islands in the HMS Beagle. The captain of the Beagle was Captain Robert Fitzroy, an illegitimate descendent of King Charles II.

Charles Darwin was only twenty when he left England in 1831. Thirty years later he published his theory of evolution, unquestionable one of the most revolutionary ideas science has ever known.

Because of Charles Darwin's "discovery" of these islands, much attention has been paid to them and many fascinating things have been discovered.

second voyage of the beagle
Second Voyage of the Beagle

The second voyage of H.M.S. Beagle lasted from 27 December 1831 until 2 October 1836, a total of 1,740 days. This itinerary, which counts specifically whether Darwin spent the night on board the Beagle or on land, has been calculated using the Beagle diary. Darwin stayed ashore for some days when the Beagle was travelling elsewhere. According to these calculations, Darwin had the following itinerary:

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At Sea: 580 days or 33.3 % 
At anchor: 566 days or 32.6 % 
On land: 594 days or 34.1 %

Darwin's nights on board the Beagle: 1,144 nights or 65.8 %

Darwin's nights on land: 596 nights or 34.2 % (955 nights, or 55%, were spent in South America).

darwin s finches
Darwin's Finches

Darwin's finches (also known as the Galápagos Finches or as Geospizinae) are 13 or 14 separate combinatory species of Passerine birds (related to American Emberizidae or Tanagers rather than European finches) related to a group that Charles Darwin collected on the Galápagos Islands during the voyage of the Beagle. Thirteen reside on the Galápagos Islands and one on Cocos Island.

The birds are all about the same size (10–20 cm). The most important differences between species are in the size and shape of their beaks, and the beaks are highly adapted to different food sources. The birds are all brownish or black.

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These finches probably descended from one type of ancestor and then, due to isolation and through chance, different climates and natural forces such as food availability and type, they evolved into thirteen different types of finches.

The process of their evolution would probably have begun with immigrants from the mainland. As they dispersed to different islands, new populations would be formed. Every time these satellite populations dispersed, there would be greater difference between the individual species.

the evolution of his thinking
The Evolution of his Thinking

On the Galápagos Islands and afterwards, Darwin thought in terms of "centres of creation" and rejected ideas of transmutation of species. From Henslow's teaching he was interested in geographical distribution of species, particularly links between species on oceanic islands and on nearby continents.

submitting to authority
Submitting to Authority

Following his return from the voyage, Darwin presented the finches to the Geological Society of London at their meeting on 4 January 1837, along with other mammal and bird specimens he had collected. The bird specimens, including the finches, were given to John Gould, the famous English ornithologist, for identification. Gould set aside his paying work and at the next meeting on 10 January reported that birds from the Galápagos Islands which Darwin had thought were blackbirds, "gross-beaks" and finches were in fact "a series of ground Finches which are so peculiar [as to form] an entirely new group, containing 12 species."

journal entry 1837
Journal Entry, 1837

"A group of finches, of which Mr. Gould considers there are thirteen species; and these he has distributed into four new sub-genera. These birds are the most singular of any in the archipelago.... All the species, excepting two, feed in flocks on the ground, and have very similar habits. It is very remarkable that a nearly perfect gradation of structure in this one group can be traced in the form of the beak, from one exceeding in dimensions that of the largest gros-beak, to another differing but little from that of a warbler."

natural selection
Natural Selection

In 1839 Darwin conceived of his theory of natural selection, and he added more detail to the second edition, published as Journal of Researches in 1845, with an illustration showing the beaks of four finches and the closing remark that "Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."