Galapagos, Darwin and the Theory of Evolution

Dr Geoff Carter made a welcome third appearance before Todmorden U3A members at their March General Meeting. On this occasion, his topic was Galapagos, Darwin and the Theory of Evolution. Darwin had both a good and a less auspicious start in life. He was born into a well-to-do family, his mother Susannah being of the Wedgwood family and his father a successful doctor. His grandfather, also a doctor, achieved the unlikely feat of writing racy, sexy poetry about vegetables, Geoff informed his audience.

 

His education record gave no indication of what was to come. He was sent to Shrewsbury School, which duly sent him back home where he was tutored. His father then despatched him to Edinburgh to train for the family profession. This he abandoned, due to boredom and to witnessing the amputation – without anaesthetic – of a girl’s leg, which he viewed as barbaric. He was then packed off to Cambridge to study divinity. This suited the young Darwin as it meant he could have a living and still find time to pursue the scientific interests which he had already developed. He was progressing in this thanks to learning field craft from John Henslow, Professor of Minerology, who was an ardent naturalist. Like many a student before and since, Darwin had a high old time with drink and women, and left Cambridge with what Geoff described as “a weedy degree”.

 

Geoff then moved on to a more familiar episode in Darwin’s life: the voyage of HMS Beagle, a marine survey ship. An advert appeared for the post of a naturalist to be a companion to the Captain of the ship, Robert Fitzroy – he who pioneered weather forecasting, he coined the term, and after whom the shipping area is named. Henslow, dissuaded by his wife from accepting the post, put Darwin’s name forward.

 

The voyage of the Beagle took five years, of which five weeks were spent in the Galapagos. Darwin explored the land, examined the geology, collected fossils and made detailed observations of plants, animals and birds, specimens of which were sent back.

There is a generally held misconception that the eponymous Darwin’s Finch gave the impetus for him to develop his theory of evolution. Although Darwin noted the gradation of different beak sizes in this species, he failed to note on which island he found those differences. Geoff explained that this was the crucial in the case of the mockingbird. Darwin noted which subtle variation in this species appeared in the birds on each island. It was this that later prompted Darwin’s thinking when closer examination by ornitholigsts determined that were different species rather than varieties.

 

Another important observation of Darwin’s was that although there is a considerable degree of resemblance in the volcanic nature of the soil, in climate, height, and size of the islands, between the Galapagos and Cape Verde Islands, the life found in each was entirely different. The species on the Cape Verde Islands off the west coast of Africa resembled those found on the mainland. Similarly, those found on the Galapagos were similar to those found on the South American mainland. Darwin drew the conclusion that each of the groups of islands could be colonised from the mainland and then modifications in the species take place.

 

The Beagle spent a year returning, arriving back in October, 1836. Darwin started to develop his theory during this time. In 1839, he married his cousin Emma Wedgwood and her wealth meant that he could devote himself to science for the rest of his life. He completed the development of his theory in 1838, and although his ideas were not completely unknown to others, he was collaborating with and learning from other scientists of various disciplines, he did not publish for another 21 years. Part of the reason was that he did not want to hurt his wife, who was a devout Unitarian. He also knew that publication would cause a furore and that he would undoubtedly face a great deal of personal attack. His hand was forced when his close friend and fellow geologist, Sir Charles Lyell, read a paper by Alfred Russel Wallace. The paper outlined similar ideas to Darwin’s and Lyell urged Darwin to publish to establish precedent. He did nothing for almost three years until in June, 1858, when Russel himself sent Darwin a paper outlining his own theory.

 

The upshot was a joint presentation to The Linnean Society but which did not cause a stir. This came about when Darwin completed the book he had undertaken and finally finished in 1859. Publication took place in November of that year after encouragement from friends and Lyell taking responsibility for placing it with John Murray. The expected attacks came and Dariwn withdrew, leaving it to friends such as Joseph Hooker and Thomas Henry Huxley to defend him and his theory. Queen Victoria rejected his theory and for this reason Darwin received no knighthood. In his later years he became a recluse and died after an illness in April, 1882.

Report by John Bouttell

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