Charles Darwin and the Beagle: how the voyage transformed our understanding of the world

What type of vessel was the Beagle?

Built in 1820 as a Cherokee-class, ten-gun brigsloop, the Beagle was later refitted as a survey barque. At that time, the British had a keen eye on South America, where several nations had recently won independence from Spain and, in 1826, the Beagle embarked on a hydrographical survey of Patagonia and Tierra del Fuego, initially under the captainship of a Pringle Stokes. When Stokes took his own life in Tierra del Fuego, he was ultimately replaced by former flag lieutenant Robert FitzRoy – a 23-year-old who’d been in the Navy since the age of 13.

The Beagle returned to England with four Fuegians on board – two men, a boy and agirl – captured by the crew while in pursuit of a stolen boat in Tierra del Fuego. Nicknamed York Minster, Fuegia Basket, Jemmy Button and Boat Memory, these bewildered figures became the subjects of an experiment by FitzRoy, who intended to ‘civilise’ them with English manners and a Christian education, and then return them home to spread the word. Boat Memory died of smallpox in England, but FitzRoy persevered with his plan when he was commissioned to captain a second South American survey.

After Stokes’ death, FitzRoy wanted a self-funded scientist to accompany him on the expedition, as a gentleman companion. The position was offered to botany professor Reverend John Stevens Henslow, who instead put forward his pupil and protégé Charles Darwin.

The Beagle initially departed Devonport on 10 December, but was delayed in Plymouth by bad weather and then Christmas drunkenness. When the vessel eventually weighed anchor, Darwin instantly became sea sick and began questioning the wisdom of his mission. He was confined to his cabin for some time, completely missing Madeira, their first port of call.

In Tenerife, faced with 12 days’ quarantine because of a cholera outbreak in England, FitzRoy ordered the ship to proceed straight to the Cape Verde Islands. On Santiago, Darwin found a band of seashells 18 metres up a cliff face. He noted this as evidence of dramatic change in global sea levels, which seemed to support a controversial concept, previously put forward by geologist Charles Lyell, that the world had slowly changed over a huge period of time – this would be influential on Darwin’s theories. The Beagle crossed the equator on 16 February and, 12 days later, reached Brazil.

On Santiago, Darwin found a band of seashells 18 metres up a cliff face. He noted this as evidence of dramatic change in global sea levels

For two months, Darwin roamed Rio de Janeiro and its surrounds, collecting specimens. He explored rainforests around Rio Macaé and Botafogo Bay, while FitzRoy surveyed the Abrolhos Archipelago. Two crew members died of malaria in Brazil, and the ship’s surgeon, Robert McCormick – upset at playing second fiddle to Darwin – resigned and returned to England.

On 26 July, the Beagle arrived in Montevideo, where FitzRoy surveyed the Rio Paraná and sent 50 of his men to help local officials quell a riot. Here, Darwin shipped the first batch of specimens and notes back to his mentor, Reverend Henslow, wracked with doubt about the quality of his work.

What did Darwin collect on the Beagle voyage?

Darwin spent several weeks collecting specimens in Patagonia, around Bahía Bianca. There, he discovered huge fossil bones in a cliff at Punta Alta, which later proved to belong to long-extinct and previously unknown creatures including giant sloths and armadillos. Further south down the coast, he also found the bones of a llama-like, humpless camel.

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The expedition departed Montevideo on 27 November, and Tierra del Fuego was sighted on 18 December. For a month, the Beagle was battered by tempestuous seas around Cape Horn, once almost capsizing – an incident that caused the loss of a significant stash of Darwin’s specimens.

Eventually, in smaller boats, FitzRoy and a landing party – including Darwin – entered the Beagle Channel (named after the ship during its previous expedition) and travelled along Ponsonby Sound to Woolya Cove. Here, the three surviving Fuegians were deposited, dressed in European clothing and armed with bags of trinkets and utterly useless gifts (such as tea sets) from a well-meaning British public.

The party built a small missionary post and, on 27 January 1833, Darwin and FitzRoy farewelled Reverend Richard Matthews, who remained behind with the three Fuegians to man the mission. Nine days later, when FitzRoy returned to see how his Anglicised ambassadors were progressing, he was disappointed to find that the site had been looted. Matthews had already had enough, and rejoined the Beagle, leaving the three Fuegians to their fate.

After a foray to the Falkland Islands – where FitzRoy supplied security for newly established British interests, and purchased a second boat – the expedition moved back up the east coast of South America.

While the Beagle and the new schooner (christened the Adventure) completed marine surveys, Darwin spent long periods exploring on land. As well as collecting specimens, he experienced gaucho culture during wild adventures on the Pampas.

What did Darwin's Beagle expedition find?

Beyond the discovery of giant bones belonging to extinct monsters like Mastodons and Megatheriums, these trips were highly eventful. During one extended excursion, Darwin travelled for a period with General Juan Manuel de Rosas – future dictator of Argentina.

This overland epic saw him complete a 200- mile horseback ride from Carmen de Patagones on the Rio Negro to Bahía Blanca, via the Rio Colorado. He then spent 12 days travelling 400 miles from Bahía Blanca to Buenos Aires, climbing the Sierra de la Ventana mountains en route, and subsequently riding along South America’s second longest river, Rio Paraná, for a further 300 miles to Santa Fe.

Attempting to return by riverboat down the Paraná, he arrived in Buenos Aires as a revolt was unfolding and became trapped, eventually escaping by boat to Montevideo, where he finally rejoined the Beagle.

Besides the evidence he was amassing about an entire strata of megafauna that had mysteriously disappeared, Darwin also found puzzling clues to another conundrum during his foraging forays, including teeth from a horse-like creature that pre-dated the arrival of Europeans to South America. These led him to question why species so similar to surviving animals could have disappeared.

As his collection grew, he took on a servant to help with the process of shooting and stuffing animals, and sending packages back to England. Occasionally, specimens found him. Darwin had been long been looking for a rare sub-species of rhea bird reported by the gauchos. In January 1834, while enjoying a meal shot by expedition artist Conrad Martens, the scientist suddenly realised he was eating the very elusive animal he’d been searching for.

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After travelling back down the flank of Patagonia – via the Falkland Islands, where FitzRoy’s men helped quash a revolt – the Beagle visited the mission in Tierra del Fuego. It was deserted. Jemmy Button remained nearby, but he’d shed his clothes, taken a wife and returned to a traditional way of life.

The expedition negotiated the Straits of Magellan in June 1834, entering the Pacific and turning north along the Chilean coast. In Valparaiso, Darwin ventured inland again, as far as Santiago and even Mendoza in Argentina, crossing the foothills of the Andes and making more observations about geological forces. On his return, he contracted a parasitic illness – possibly Chagas’ disease – that would cause him lifelong problems.

While in Chile, Darwin witnessed the effects of a volcanic eruption on Osorno and an earthquake in Concepción, prompting him to postulate about plate tectonics and the possibility that South America was rising from the sea (another theory put forward by Lyell).

On 15 September 1835, the Beagle reached the Galápagos Islands, where Darwin would make his biggest discoveries – helped by a chance encounter. When the scientist met Nicolas Lawson, the acting Governor of Galápagos happened to mention that he could tell which island a tortoise was from according to the shape of its shell.

Darwin subsequently noted differences between mocking birds native to individual islands and, although he didn’t label them at the time, collected finches from the archipelago that would become central to his theory of natural selection and evolution.

When did the Beagle return?

Heading west across the Pacific, the Beagle visited Tahiti – where Darwin explored his theory about the formation of coral reefs by sinking volcanic islands – and New Zealand.

Though disappointed by the lack of mammalian life in New Zealand, Darwin was spellbound by the wonderfully weird marsupials of Australia. After arriving in Sydney in January 1836, he travelled inland to the Blue Mountains, and later explored Tasmania and King George Sound (current-day Albany in Western Australia), before the Beagle sailed for Cape Town, via the Cocos Islands and Mauritius .

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Using St Helena and Ascension Island as stepping stones, FitzRoy took the expedition across the Atlantic and back to Brazil, to double check his previous readings. From here, the Beagle finally trotted home, via the Azores, to arrive in Falmouth on 2 October 1836 – three years later than planned.

Darwin disembarked from the ship he would make famous, armed with ideas that would become the cornerstones of modern biology – even if it did take him two decades to make them public.

In 1839, Darwin conceived his theory of natural selection (that all species of life have evolved over time from common ancestors), but didn’t make it public until another naturalist and explorer, Alfred Russel Wallace, independently came up with the same concept. The two men’s ideas were released together in 1858 (without Wallace’s prior approval), and Darwin published his ideas in full in On the Origin of Species the following year. The theory split opinions – particularly in the Church of England – but ultimately became a foundation stone of modern natural history.

Pat Kinsella specialises in adventure journalism as a writer, photographer and editor

This article first appeared in BBC History Revealed in 2016