This year we celebrate both the 200th anniversary of Charles Darwin’s birth, and the 150th anniversary of the publication of his seminal work, On the Origin of Species. Few historical figures can claim to have had an impact as far reaching and profound as Darwin, and few scientific ideas have changed our understanding of the world around us quite as radically as his have. This year a special set of stamps and a commemorative two pound coin have been released.

Born into the Darwin-Wedgewood family in 1809, he initially trained to be a doctor, expecting to follow his father into the medical profession. However, he quickly grew bored of medicine and found surgery distressing, preferring to focus on studying natural history. His father was upset by this lack of interest in medicine and moved him to Cambridge in the hope that he would become a priest. Darwin studied there for three years, until one of his close friends suggested he accompany Robert FitzRoy on an expedition to chart the coast of South America. He was meant to aid FitzRoy as a geologist and to be a gentleman companion.

Darwin spent three and a half years of the five year expedition on land, collecting fossils and specimens. It was on this expedition that his famous visit to the Galapagos Islands took place, although a perhaps equally important influence was his discovery of the fossilised remains of gigantic extinct mammals. The similarities these had with modern mammals would have given him additional evidence that different species are related to each other.

Darwin worked through his notes on the return voyage, and his later writings suggests that he had already begun to formulate his ideas on the nature of species. When he eventually returned to England he was fairly well known among scientific circles, due to the popularity of his letters on geology. While he had begun jotting down his now famous ideas on the changing nature of species, he did not publish them due to their controversial nature. It was only when the naturalist Alfred Wallace wrote a paper expressing similar ideas to Darwin’s own, that Darwin began to work on a book, which was to be titled Natural Selection. Darwin and Wallace began a correspondence, and eventually a joint presentation was made by friends of Darwin to the Linnean Society, a major scientific society. Darwin, however, did not attend due to the recent death of his infant son.

The presentation received a lukewarm reaction, and little attention was paid to it initially. However, the publication of On the Origin of Species generated intense international interest and much public debate. Some members of the Church welcomed Darwin’s ideas, interpreting natural selection as a process designed by God, while others criticised it as heresy. The scientific community slowly began to support natural selection, albeit mostly in a reserved manner.

While the idea of evolution was not new, Darwin’s theory of natural selection was. It became one of the most important theories of this millennia, perhaps second only to Einstein’s theories in terms of how far it has advanced our understanding of the world around us.

Darwins’s theory can be summarised thus:

Within a species there is variation between individual members, and much of this variation can be passed on to their offspring. Since there is competition for limited resources, and more offspring are produced than can survive to adulthood, only those with the most beneficial traits will successfully reproduce.

Or, as Darwin himself put it: “As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.”