Survival of an eminent Victorian thinker

Charles Darwin's theory of evolution puts him at the centre of today's debate on the origins of the Universe. Now, even the Bank of England is marking his genius.

With that great, grey beard, and those deep-set eyes overhung by that huge, domed forehead, Charles Darwin's image is the physical embodiment of the intense Victorian thinker. The portrait chosen by the Bank of England for the back of the new £10 note is the Darwin we all think we know: sagacious, aged and just a touch fuddy-duddy.

With that great, grey beard, and those deep-set eyes overhung by that huge, domed forehead, Charles Darwin's image is the physical embodiment of the intense Victorian thinker. The portrait chosen by the Bank of England for the back of the new £10 note is the Darwin we all think we know: sagacious, aged and just a touch fuddy-duddy.

Darwin, a failed medical student who often preferred rat-catching to studying, was in fact an unexpected hero of 19th century intellectualism. As a young man he was an adventurer extraordinaire who packed a pistol in his waistcoat and a cosh up his sleeve. Yet his life's work successfully challenged the entrenched view of the church. His momentous theory of evolution not only explained life on Earth, it also told us much about our place in it.

Barely a week passes without another book being published on some aspect of evolution which pays handsome tribute to the man who discovered the importance of natural selection in driving the immense diversity of life, from seabed to mountain top. It is not only biologists who are enamoured with just how correct Darwin's theory has proven to be. Philosophers, economists, sociologists, technologists, and psychologists are discovering that Darwin's "one long argument" also has implications for understanding their own intellectual field.

As a theory, evolution has more than withstood the rigours of time. As scientific achievements arise, Darwinism looks stronger than ever. When Mendelian genetics became established in the early 20th century, accompanied by the discovery of chromosomes, it explained many of Darwin's observations about heredity. When the DNA helix was unravelled 50 years later, it served to underpin the molecular basis that could explain the genetic variation on which the forces of natural selection act.

And now, nearly 150 years after Darwin's greatest work, modern evolutionary theorists, from John Maynard Smith and Richard Dawkins to Mark Ridley, continue to sing the praises of the master genius who dared suggest that the biblical version of creation might not be the literal truth.

It would be correct to say that Darwin's genius was a slow burner. He dropped out of medical school in Edinburgh and, in an act of near-despair, read theology, Euclid and the classics at Cambridge. Born in Shrewsbury in 1809, he came from a prosperous middle-class family, but his early struggles with academic life created some friction with his father, who was himself the son of a famous philosopher, Erasmus Darwin. "You care for nothing but shooting, dogs and rat-catching, and you will be a disgrace to yourself and your family," his father told the young Charles.

Mr Darwin senior was intent on getting Charles into the church, the established reliquary for dissolute sons. But Charles had different ideas. He managed to secure a position on HMS Beagle, which was to chart unexplored waters at the far ends of the world. His father eventually gave way after Charles's uncle, the pottery magnate Josiah Wedgwood, interceded on the young man's behalf.

It is difficult to imagine in an age of jet travel and in-flight entertainment just what it meant to sail for months at a time with 73 companions on a 10-gun naval brig just 90 feet long and 24 feet wide. For days on end, Darwin was seasick and miserable. Yet he managed to win promotion, from being the captain's dinner companion to becoming the ship's official naturalist. He relished organising the surveys and the collection of specimens that would eventually earn him professional recognition as a scientist when he finally returned to England four years, nine months and two days after leaving Southampton.

When the Beagle's survey work brought Darwin to land on South America, his lust for adventure was truly unleashed. It is hard to envisage looking at the face on the back of the new £10 note that this was the man who rode roughshod with the toughest gauchos of the Argentine pampas, brought down flightless birds with swinging bolas and amused his drinking companions with the trick of lighting matches on this teeth.

For weeks on end, Darwin would sleep under the stars as he crossed the continent. He trekked along the Andean peaks, getting nosebleeds at dizzy heights, and marvelled at every spectacle. He hunted game, kept meticulous notes of all that he saw, and experienced the frightening thrill of an earthquake, which made him realise that nothing is immune to change.

One of his greatest insights was to realise that the marine fossils he discovered high up a mountainside were there not because of an extraordinarily high flood in the past - an explanation favoured by theologians - but because the ancient coastline itself had been pushed ever higher as the mountains moved, quite literally.

The earthquake Darwin lived through in Chile did much to shake his belief in the immutable face of nature.

But it was of course his visit to the Galapagos, a volcanic outcrop of 15 islands some 600 miles west of Ecuador, that lit the spark igniting his theory of evolution. At first, he was oblivious to the fact that each island seemed to have its own species of finch and tortoise. It was only later that he realised that the geographical diversity had come about through evolution from common ancestors, who arrived perhaps after a storm on the mainland many years previously.

There is no doubt that Darwin was a God-fearing believer when he left England at the age of 22, and was probably still one when he returned nearly five years later. Some biographers believe he finally rejected God after his beloved 10-year-old daughter, Annie, died of a lingering illness. In any case, agnostic or atheist, Darwin came from a liberal Whig family who were used to bucking convention.

Over 20 years, following his return, he ruminated over his vast specimen collections and, between his many other writings, secreted away his magnus opus, a book manuscript that he left to gather dust for many years in a broom cupboard at Down House in Kent, fearful of the effect its publication would have. He finally published it in 1859, when he was 50. The full title of the first edition was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

Leading theologians immediately rejected the idea of evolution from common ancestors as dangerous nonsense. Darwin himself was famously asked whether his ape ancestors came from his mother's or father's side of the family. Even today his theory is rejected by many religious fundamentalists, both Christian and non-Christian. It was, after all, only four years ago that the Pope ruled that evolution was now "more than a hypothesis".

The first edition quickly sold out. Darwin rewrote the work for a further five editions, shortening the title to The Origin of Species. The word "evolution" does not occur at all in the first edition, which only gives a passing reference to man, preferring instead to concentrate on the animals and plants Darwin knew something about. "In the distant future I see open fields for more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by graduation. Light will be thrown on the origin of man and his history," Darwin wrote.

Even though this was all he had to say of man, the implications of the theory for human origins were immense. It meant that we were merely the products of blind chance and natural selection operating over many millions of years, just like any other life form that has ever existed. We may think we are special - and human consciousness still cannot be explained by Darwinist theory - but in an evolutionary sense we are little different from a mouse or a microbe.

Against his better judgement, Darwin did try to mix humans into the evolutionary soup in his later book, The Descent of Man, published in 1871, 11 years before his death. He admitted that he never intended to publish his thoughts on the subject "as I thought that I should thus only add to the prejudices against my views", he wrote in the book's introduction. Yet his measured account of how evolution might explain some human attributes is a lesson for those social scientists today who aim to do something similar.

"The Descent of Man addresses an extraordinary number of problems that are, at this moment, on the minds of many biologists, psychologists, anthropologists, sociologist and philosophers," wrote Robert May, the mathematical biologist, in 1981. Sir Robert, former chief scientific adviser to the government, would, I think, be the first to accept that his own words of nearly 20 years ago are just as prescient today. "It is the genius of Darwin that his ideas, clothed as they are in unhurried Victorian prose, are almost as modern now as they were when first published."