London

After visiting his family, Darwin moved back to Cambridge, although he quickly realized that much of the scientific expertise he needed, had to be found elsewhere. A few months later, he moved to London where he stayed for five productive years. Herel, he was introduced to his big inspiration, geologist Charles Lyell, who was instantly excited about the well-travelled, enthusiastic and intelligent naturalist. Lyell made sure that Darwin was introduced into both the scientific circles and society in London. Darwin’s older brother Erasmus was also living in London by now and helped him create a happy, safe and vivid life for himself.

His experiences, the materials and the conclusions established by experts in London, seriously brought new ideas to Darwin. In 1837, he started to write down his thoughts on the origin of species, thoughts which about twenty years later would revolutionise the way we understand nature. He now knew that variations in plants and animals over a long period of time could develop into different species. He made a sketch of what he thought the process looked like – an evolutionary tree. Here all species had a similar descent from which they had developed. The branches represented all the different species, living as well as extinct. Darwin considered using a coral as a metaphor instead. The foot of a coral is dead and would therefore illustrate the relationship between living and extinct species in a better way. He did, however, stick with the evolutionary tree, which has since become one of the most important icons of the evolutionary theory.

Even though Darwin was convinced about the development of the species, he still needed the mechanism that made this process happen. This came to him in 1838 as he was reading the economist Thomas Malthus’ work on increase in population from 1798. “This is finally a theory I can work with”, Darwin later wrote in his biography. Malthus argued that population was being regulated by sickness and starvation. This made Darwin realise that death was an important regulating mechanism for life in the struggle for existence. He called this mechanism natural selection.

Darwin married his cousin Emma Wedgwood in January 1839. The wedding was postponed for a week due to Darwin’s admission in the Royal Society, an great honour which he happily accepted. Later that year, he published his description of his journey with the HMS Beagle. The book was an instant success. In 1842, he recorded his now finished theory, but did not publish it just yet. The family left London and settled in Down House in the small village of Kent.

Peter C. Kjærgaard.