A letter that changed the world...

...arrived in Darwin's post 150 years ago last week. It is remarkable to think about this kind of potent correspondence in this age of instant messaging, isn't it? Here's how the story begins:

In early 1858, on Ternate in Malaysia, a young specimen collector was tracking the island's elusive birds of paradise when he was struck by malaria. 'Every day, during the cold and succeeding hot fits, I had to lie down during which time I had nothing to do but to think over any subjects then particularly interesting me,' he later recalled.

Thoughts of money or women might have filled lesser heads. Alfred Russel Wallace was made of different stuff, however. He began thinking about disease and famine; about how they kept human populations in check; and about recent discoveries indicating that the earth's age was vast. How might these waves of death, repeated over aeons, influence the make-up of different species, he wondered?

Then the fever subsided - and inspiration struck. Fittest variations will survive longest and will eventually evolve into new species, he realised. Thus the theory of natural selection appeared, fever-like, in the mind of one of our greatest naturalists. Wallace wrote up his ideas and sent them to Charles Darwin, already a naturalist of some reputation. His paper arrived on 18 June, 1858 - 150 years ago last week - at Darwin's estate in Downe, in Kent.

Darwin, in his own words, was 'smashed'. For two decades he had been working on the same idea and now someone else might get the credit for what was later to be described, by palaeontologist Stephen Jay Gould, as 'the greatest ideological revolution in the history of science' or in the words of Richard Dawkins, 'the most important idea to occur to a human mind.' In anguish Darwin wrote to his friends, the botanist Joseph Hooker and the geologist Charles Lyell. What followed has become the stuff of scientific legend.

[From How Darwin won the evolution race | Science | The Observer]

Go read the rest to kick off the celebrations for the sesquicentennial anniversary of this momentous event in human history. And while online, check out the original essay in the letter from Wallace which set things in motion, available via the Alfred Russel Wallace Page. You can also download a pdf version of the essay as part of a volume of Wallace's writings courtesy Google. The joint paper from Darwin and Wallace presented to the Royal Society is, of course, available in its entirety, with some added commentary, via Darwin Online.