How one man’s observations and ideas helped to change the world Charles Darwin 1809 - 1882 How one man’s observations and ideas helped to change the world

Charles Darwin – the boy Charles Darwin was born on 12th February 1809 in Shrewsbury, England. He went to boarding school in Shrewsbury and in 1825 went to Edinburgh University to study medicine. Whilst in Edinburgh Darwin investigated marine invertebrates and started to develop a growing interest in natural history. In 1827, at the age of 18, Darwin realised he did not like the study of medicine and could not bear the sight of blood or suffering. He left Edinburgh for Cambridge University with the idea of becoming a clergyman.

Charles Darwin – the young man Whilst at Cambridge Darwin met a number of people who were influential in shaping his career. His cousin William Darwin Fox, who was a keen collector of beetles. John Henslow, who studied and lectured on plants. Professor Adam Sedgewick, who taught him about geology during an expedition to Wales in 1831. In August 1831, Henslow wrote to Darwin inviting him to become a naturalist for Captain Fitzroy on the survey ship the Beagle.

The voyage of the Beagle 1831 - 1836 After two false starts, the Beagle set sail on her voyage on 27th December 1831, with Charles Darwin aboard. The voyage lasted 5 years. The ship sailed to South America to carry out surveying work, and everywhere it went Darwin took detailed notes of what he saw and collected many specimens. Galapagos

The Galapagos Islands Charles Darwin arrived in the Galapagos, a group of volcanic islands off the coast of Ecuador, South America on 15th September 1835. The observations Darwin made during his visit were to be influential in the formation of his scientific theories.

The Galapagos Islands The Beagle visited four of the Galapagos Islands in a period of five weeks, beginning September 15th 1835. The islands visited were San Cristóbal, Floreana, Isabela and Santiago. During his time on the islands, Darwin collected specimens of many of the different plants and animals he observed, and detailed drawings were also made. As well his observations on the species on the islands, Darwin also wrote descriptions of the geography and geology of each island in his diary.

The Galapagos Islands One species which Darwin wrote many observations about was the Galapagos giant tortoise. “It was confidently asserted, that the tortoises coming from different islands in the archipelago were slightly different in form; and that in certain islands they attained a larger average size than in others” Darwin also mentioned a number of times in his writings that the tortoises were a good source of meat for explorers and the island’s inhabitants. He noted that the number of tortoises on some islands had been greatly reduced, and in fact giant tortoises are now extinct on Floreana. “...the main article of animal food is derived from the tortoise. Their numbers in this island have of course been greatly reduced…”

Variety is the spice of life Darwin was amazed at the wide variety of plants and animals he found during his voyage to the Galapagos Islands. The images below show some of the vertebrates that Darwin saw. Galapagos marine iguana Galapagos hawk perched on Galapagos giant tortoise Vermillion flycatcher

Darwin - the collector Darwin collected numerous specimens of plants and animals and kept detailed records of where and when he had found them. Many of the species he collected and classified were new to science at the time. Lots of Darwin’s specimens are still preserved in collections in universities and museums. Large ground-finch - Charles Darwin’s specimen

Darwin observed that each island had its own unique mixture of plants and animals. These were often adapted to survive in the different conditions found on each island. San Cristobal mockingbird – only found on San Cristóbal Medium tree-finch – only found on Floreana Daisy tree Scalesia divisa – only found on San Cristóbal

Darwin’s finches Darwin made detailed studies of one group of birds, the finches, because of their strong similarities and subtle differences. He noticed that the different finch species varied in size, beak size and shape, and behaviour. He thought that these differences could be best explained if the finches had gradually become adapted to suit the conditions on the island they inhabited. He presumed therefore that all 13 species of finch found on the islands must be closely related. He also deduced that the individuals with the best set of adaptations for each island’s habitat would be most likely to survive and breed.

Darwin’s finches Small ground-finch Medium ground-finch Large ground-finch

On the Origin of Species Darwin completed his voyage on the Beagle in 1836. For over 20 years Darwin continued to do experiments and collect data based on his ideas about the importance of adaptation and survival. In June 1858 he received a letter from Alfred Russel Wallace, another naturalist and explorer who was collecting specimens in Indonesia. Wallace shared similar ideas to Darwin about how living things could adapt and evolve. In November 1859, Darwin published his famous book ‘On the Origin of Species by Means of Natural Selection’ in which he described his evidence for evolution - much of which was first collected during the voyage of the Beagle.