Charles Darwin and Evolution by Natural Selection
It was the death of Robert Brown, vice- president of the Linnean society of London that caused a special general meeting of that august body to be called for the 1st day of July 150 years ago and led to the first public airing of one of the most remarkable scientific claims of all time. The meeting at Burlington House (now the home of the Royal Academy) was convened to elect a new vice-president but, perhaps to attract a quorum during the summer season, the papers due for the following meeting were to be read. A scheduled paper by botanist, JD Hooker was withdrawn by the author to admit joint papers: one from his friend, the renowned biologist Charles Darwin and the other from the little known Alfred Russel Wallace outlining a new theory of biological evolution.
Over 25 years previously Charles Darwin signed up as a naturalist and companion to Captain Fitzroy for the Beagle voyage as a rather aimless 22 year old and had returned five years later as a dedicated and focused scientist. The voyage of the Beagle was to influence the course of his life. He became a best selling author with his accounts of the voyage, whetting the great Victorian interest in travel, exploration and exotic tropical species. In addition to the animal and plant specimens he collected, Darwin also returned from the Beagle voyage with the seeds of a great idea: how evolution of species might work. Darwin didn't invent or discover biological evolution - evolution had quite a currency already. Indeed, it was in the family - Charles' grandfather, Erasmus Darwin had proposed evolution in his book Zoonomia at the end of the 18th century. Improvement of domesticated animals through selective breeding was of great importance to the land owning gentry. Many philosophers had considered the great variety of species and observed that species seemed to be well adapted for their environments. The problem was that no-one could satisfactorily explain how or why evolution might work. Darwin would spend the greater part of the rest of his life working on this theory.
Surprisingly the two great influences on Darwin's thinking were geology and economics. Charles Lyell's book the Principles of Geology, which Darwin read on the Beagle voyage showed how the scientific study of rocks could reveal the origins of those rocks to show the evolution of the earth. Why therefore, could study of living things not unlock the origin of species? Lyell was later to become a lifelong friend. What provided the key was a work on population by a clergyman Thomas Malthus which appeared around the same time as Erasmus Darwin's Zoonomia. Malthus observed that living creatures reproduced at such rate that, if unchecked, the population would exceed the capacity of the environment. Therefore an endless struggle for survival was inevitable. This provided the clue Darwin needed. In any species there are differences between individuals. Some individuals will be better suited to the environment than others. These individuals will have a better chance of surviving and reproducing. They will therefore pass on the advantageous traits to their descendents. In this way the species develops over successive generations to be better adapted to the environment: this process Darwin termed natural selection. Darwin had worked out his theory of evolution by natural selection by 1840 and had revealed it to his close friends Lyell and Hooker in an essay in 1844.
By 1858 and approaching fifty, the cautious Darwin had kept his discovery a virtual secret for over twenty years but he was finally organizing his vast notes to unveil his theory to the public in a great book. Then he received a bombshell. A letter arrived from Borneo from a naturalist by the name of Alfred Russel Wallace which outlined the essence of Darwin's theory. Darwin, realizing that he might lose his claim to precedence turned to Lyell and Hooker for help. It was they that suggested that Darwin submit some of his material along with Wallace's correspondence. The rest, as they say, is history.
After the Linnean meeting, Darwin moved quickly to publish his ideas the following year with the rather long title "The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life". Seldom has a book incited such an immediate and excited reaction. Not surprising, as it challenged the accepted beliefs about creation. Centuries earlier Copernicus and Galileo had shown that the earth was not at the centre of the solar system, geology had debunked Noah's deluge and was showing the earth to be much older than an age of under 6,000 years calculated by Bishop Ussher. Science had come in conflict with literal interpretation of scripture and science had won. But, this was different - the human race may be an accident, a chance occurrence. What followed was an unholy row with Samuel Wilberforce, the Bishop of Oxford asking Darwin's zealous supporter T.H. Huxley whether he was descended from an ape on his grandfather's or grandmother's side. Darwin a retiring man, never publicly spoke on evolution and the rapid spread of the idea can be attributed to the storm created around the book and the work of Darwin's supporters such as Huxley.
In the intervening 150 years the evidence has mounted for evolution by natural selection to a point that it is universally accepted in biological science. Outside of science, disbelief and confusion is still widespread. Unfortunately the phrase "survival of the fittest" has been misunderstood and misrepresented to give some very objectionable ideas some pseudo-scientific support. In the US the storm still rages, where evolution can be taught in schools, as it is science and creationism cannot, as it is religion. Opponents of evolution propose the alternative idea of "intelligent design" which they say is a scientific theory and should be taught in science class.
From 1st July 2008 to the end of 2009 which will mark the 150th anniversary of "The Origin of Species" and especially centering on Darwin's 200th birthday in February 2009 there will be celebrations around the world of this idea that changed the very way in which we view ourselves. Hopefully Alfred Russel Wallace will get his fair share of attention as had he sent his paper to anyone else you might now be reading about Wallacean Evolution.
And what of the reaction of those few who gathered at the Linnean Society in London 150 years ago and heard the first public presentation of the theory that changed the way we view the world? Well, it may have been the summer heat or the thrill of the vice-presidential election, but it seems to have had little impact on the scientific audience as in his end of year report the president stated that the year had not been distinguished by "any of those striking discoveries which at once revolutionise, so to speak, the department of science on which they bear."