Voyage of the Beagle

Between December 1831 and October 1836 the small Royal Navy survey ship HMS Beagle sailed around the world under Captain Robert FitzRoy, charting the coasts of South America for the Admiralty. On board as an unpaid gentleman naturalist was the 22-year-old Charles Darwin. His years of collecting and observation on the voyage made his name as a geologist and writer and supplied the evidence that later led him to the theory of evolution by natural selection.

After the Spanish American wars of independence opened South America to British trade, the Admiralty wanted accurate charts of its southern coasts. A first survey had been carried out between 1826 and 1830. The second was to complete the mapping of Patagonia and Tierra del Fuego, survey Chile and Peru, and carry a chain of longitude measurements round the globe, for which the ship carried 22 chronometers. FitzRoy, aged 26, also intended to return three Fuegians he had taken to England on the earlier voyage.

FitzRoy wanted a companion able to study geology ashore. Through Cambridge contacts, the Cambridge professor John Stevens Henslow recommended Darwin, a recent graduate expecting to become a clergyman. Darwin's father at first objected, but was persuaded by Darwin's uncle Josiah Wedgwood, and Darwin accepted on 1 September 1831. He paid his own way and kept control of his collections. Before sailing, FitzRoy gave him the first volume of Charles Lyell's Principles of Geology, which explained the Earth's features as the result of slow processes over vast spans of time.

After weeks of delay from gales, Beagle left Plymouth on 27 December 1831. At the Cape Verde Islands Darwin saw tropical vegetation for the first time and began to read the rocks in the light of Lyell's ideas. On the coasts of Brazil, Uruguay and Argentina, while the ship surveyed, he made long journeys inland with gauchos. At Punta Alta, near Bahía Blanca, in 1832 he dug out fossils of giant extinct mammals such as Megatherium, then known from very few specimens; sent home, they made his reputation among British scientists.

In Tierra del Fuego the missionaries' attempt to settle the returned Fuegians soon failed. The ship visited the Falkland Islands, and in 1834 rounded into the Pacific to survey the coast of Chile. Darwin crossed the Andes, finding fossil seashells at around 13,000 feet. In February 1835 he experienced a powerful earthquake near Valdivia; at Concepción FitzRoy found mussel beds lifted above the tide, evidence that the land was rising, as Lyell had argued.

Beagle reached the Galápagos Islands on 15 September 1835. Darwin studied their volcanic geology, giant tortoises and marine iguanas. He was told that tortoises differed from island to island, and he noticed that mockingbirds did too. At the time he gave this little thought, still thinking of species as created for particular places.

The ship crossed the Pacific to Tahiti, New Zealand and Australia, then studied a coral atoll in the Keeling Islands, where Darwin tested his theory that reefs form around slowly sinking islands. After calling at Mauritius, the Cape of Good Hope, St Helena and Ascension, FitzRoy recrossed the Atlantic to Brazil to check his longitudes. Writing up his bird notes on the way home, Darwin remarked that if the island differences were real, they would undermine the stability of species, his first recorded doubt. Beagle anchored at Falmouth on 2 October 1836.

Darwin returned a scientific celebrity, his letters already circulated in print by Henslow. His journal, now known as The Voyage of the Beagle, appeared as part of FitzRoy's official narrative in 1839. Darwin later wrote that South American fossils and the Galápagos species were the origin of all his views on how species change. Evidence gathered on the voyage went into On the Origin of Species, published on 24 November 1859.

Our 1815 map shows South America during the independence wars that opened it to British survey, and the 1878 map the region decades after the voyage, with independent Argentina and Chile and the Empire of Brazil.