7 February 2012

Bananas, baobab - and the germ of an idea

Guest post by Beagle archivist, writer and editor Dr Gordon Chancellor

HMS Beagle’s voyage round the world was finally under way, this time 180 years ago in February 1832. In our last post, we left the little ship on 13 January steadily working down towards Brazil on a south-southeast bearing, having not been able to stop at either Madeira or the Canaries. This was a cruel blow to Darwin, but he made the best use of his time by trawling a net behind the ship in the hope of catching something new to science.

Trawling for evolutionary ideas

Having been fascinated by strange marine invertebrates since Edinburgh University four years earlier, Darwin focused on those that seemed to be on the boundary between plant and animal. Perhaps he recalled that his grandfather Erasmus believed life had evolved from the sea? Perhaps he also suspected that his Edinburgh mentor Robert Grant’s research on marine creatures was behind Grant’s then-radical belief in evolution?

A week of firsts

The weather was beautiful and Captain FitzRoy dropped anchor at the little known Cape Verde islands on January 16th. That afternoon Darwin set foot on land for the first time out of England, in Porto Praya on St Jago Island (today’s Sao Tiago). He was fascinated by the different races of people on the island, tasted a banana for the first time in his life and "first saw the glory of tropical vegetation." It was for Darwin "a glorious day, like giving to a blind man eyes."

The next day Darwin helped FitzRoy set up an observatory on Quail Island. This was a momentous day for Darwin and the history of geology. He started collecting rock specimens and began to use a pocket-sized field notebook, now preserved at Down House. Back on board he started a ‘geological diary’ in which he recorded his interpretations. He quickly worked out that a layer of limestone in the cliff, which had obviously been laid down on the sea bed, had then been uplifted to its present position and covered by more lava.

Ilha de Fogo, Cape Verde Islands

Geology at work: putting new ideas to the testIn recognition of their friendship, FitzRoy had given Darwin the first volume of Charles Lyell’s new book Principles of Geology and the band of limestone instantly confirmed to Darwin that Lyell’s method of geology was the best available. Lyell said that geologists must interpret rocks using knowledge of present day processes, and that they could allow for unimaginable periods of time in their interpretations. Darwin was instantly converted to Lyell’s view of the Earth’s crust as constantly oscillating: any place will be sometimes under the sea, sometimes elevated above it. He could also see the immensity of time and how small gradual changes could account for anything. This was essential later for his theory of evolution.

A biblical baobab and shipboard politics

On the 20th Darwin went for a walk with the ship’s Surgeon Robert McCormick, who carved his initials on a great baobab tree reputed to be 6,000 years old; this was older than the world according to the Bible. McCormick’s nose was out of joint, as he would normally have doubled as the ship’s official naturalist and was galled at the privileges enjoyed by the gentleman Darwin. They returned on the 24th with FitzRoy and Wickham to measure and draw the tree and on the 26th Darwin went riding into the interior with Benjamin Bynoe, Assistant Surgeon. He spent the rest of his stay on further excursions inland and collecting octopuses and scores of other animals and plants. He even collected a fish which had driven its ‘teeth through Mr Sullivan’s finger’.

FitzRoy completed his magnetic experiments around February 6th, then after a three-week stay in the Cape Verdes, HMS Beagle set sail again on the 8th for St Paul's Rocks, near the equator. What a day it will be when our 21st-century Beagle crosses the line!

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