The evolution of Darwin

ONE OF the greatest geologists of the 19th century went down in history as the man behind perhaps the greatest biological discovery of all time, writes DICK AHLSTROM

Charles Darwin boarded HMS Beagleon December 27th, 1831, as a naturalist and geologist. But the planned two-year journey turned into five years, and in that time Darwin collected the evidence he used to explain evolution.

But what sort of person was he? A detailed search through the notebooks and diaries kept by Darwin has given Cardiff University’s Prof Paul Pearson interesting insights.

Darwin was a product of his times – a reasonably well-to-do young man with an interest in science. He attempted medicine in Edinburgh before switching to natural sciences at Cambridge.

He had read of Alexander von Humboldt’s adventures as a naturalist and explorer, and Darwin too resolved to pursue this ambition, according to Prof Pearson, of Cardiff’s school of earth, ocean and planetary sciences.

“As a student he had been keen on travel to the tropics. It would have been a gentlemanly travel expedition.”

He prepared himself well for this goal, studying botany with John Henslow at Cambridge and travelling through Wales to study its geology with Adam Sedgwick. “He was a most highly trained geologist,” Prof Pearson says.

BY THE TIMEthe opportunity to travel on board HMS Beaglearrived, Darwin was well prepared to serve as the ship's naturalist.

He was of the appropriate social class, but he also had a secondary role, Prof Pearson says, providing intelligent and gentlemanly company for the captain, Robert Fitzroy – something thought necessary to stave off the tedium of long sea journeys.

Once embarked, Darwin set to work immediately, taking his role very seriously. “He was doing everything, particularly geology and zoology, and also recorded people and how they lived,” says Prof Pearson. “But his geology outweighed zoology two to one. He can be regarded as a geologist, and thought of himself as a geologist.”

Darwin was well placed, however, to be sensitive to what his discoveries and findings would later tell him. Geologists had only recently shown that the Earth was actually much older than the 4,000 years suggested by the Bible.

Then there was the issue of fossils – fantastical animals embedded in ancient rocks that demonstrated that many animals had long deceased precursors.

These findings had helped develop evolution, the idea that one lineage progresses from another, retaining some changes and in time becoming quite different.

But Darwin’s contribution was discovering how the evoltuionary process was achieved. “The geological question, which was how species appeared, was for him one of the key questions in geology,” says Prof Pearson.

“Darwin and the people who taught him were doing natural theology.” God was responsible for all of this and there were few scientist dissenters at the time.

DARWIN, THROUGH HISdetailed recording of animal species seen on the voyage, was collecting the proof he would later use to explain the appearance of new species: natural selection.

He was not struck by a bolt while in the Galopogos Islands, Prof Pearson suggests. “He didn’t have his theory then. He spent most of his time collecting rocks.”

Rather, his ideas developed only when he had returned to England after the long five-year journey. “The theorising came after the voyage,” Prof Pearson says.

“The actual theory of evolution appeared to be developed in his notebooks a year or two after the voyage, as he wondered what it all meant. The ideas developed and it is all in his notebooks. He had a theory of evolution through natural selection.”

These are there to be read in his writings by 1838, but Darwin did not publish his great work, On the Origin of Species by Means of Natural Selectionuntil 24th November, 1859.

“He understood the implications of natural selection,” Prof Pearson says. God was taken to be the source delivering the spectacular variety of life, “but he realised he had an alternative explanation that didn’t need God”.

He was in no rush to publish, given the dangers of the theory so clearly exposed by the findings written into his notebooks.

“His reputation was very much at stake. Darwin wanted to be in the scientific elite,” Prof Pearson says. “He knew it was dynamite. He also had a very devout wife.”

Although he delayed, he feared an early death would prevent his theories being published. He therefore wrote them into his will so that, upon his untimely passing, natural selection would still be presented.

This proved unnecessary, however, and he will be remembered forever more for natural selection. And yet, he remained a geologist par excellence. “He became one of the top geologists of his time,” Prof Pearson says.