Credit: AFP
Armed with just a pen, Charles Darwin reforged our concept of nature and humanity's place in it, ignited a social debate that blazes to this day and shook the foundations of religions.
He bequeathed a theoretical legacy – the principle of evolution by natural selection and the origins of Man – that has not only survived assault by creationists and other critics but also remains a pillar of modern science.
The 12 February bicentenary has been elevated into a global celebration, placing Darwin among Newton, Einstein, Galileo and other greats who not only broke new ground in science but also reshaped our mental landscape.
"For my money, the most important thinker the human species has ever produced is Charles Darwin," says evolutionary biologist Richard Dawkins, author of The God Delusion and other works.
Darwin's blockbusters were two books, On the Origin of Species, whose 150th anniversary of publication falls on November 24, and The Descent of Man, published in 1871. In the first, Darwin expounded his idea of evolution by natural selection.
The evolution of species is led by individuals whose inherited characteristics enable them to best exploit their habitat. "In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment," Darwin wrote.
Some scientists of the time described Darwin's words as a stabbing ray of light, a simple but brilliant illumination.
It explained how some species survived and others were wiped out, and how environmental pressures sculpted shape and behaviour across the natural world. It took nearly a century of further work, with the discovery of DNA, to pinpoint the genetic mechanism of change.
In the second, Darwin applied evolutionary theory to humans, emerging with the then mind-blowing contention that Homo sapiens and apes descended from a common ancestor. "Man still bears in his bodily frame the indelible stamp of his lowly origin," Darwin said bluntly.
At a stroke, Darwin established humans as just another species of animal, rather than a lordly creature created in God's own image that most people at the time believed.
