Charles Darwin's five-year expedition led him to his theory of evolution. Feb. 12, 2009 will mark his 200th birthday.
(Andrew Pulley/National Geographic)More Photos
He wasn't a mathematician. He wasn't an inventor. He was just a 20-something guy who liked to poke around in the dirt.
Yet, Charles Darwin developed a theory of evolution so significant that it forms the bedrock of biology, and so radical it is still controversial in some circles today.
In 1859, when he was 50, Darwin published "On the Origin of Species," the work that outlined the theory of natural selection and left every high-schooler hankering for a trip to the Galapagos Islands.
But he was only 22 when he began the five-year adventure that led him to his legacy.
How did such a young man come up with such a pioneering proposition?
"What an astonishing thing it was," Armand Leroi, an evolution expert at Imperial College London, told ABCNews.com. "He was a young man -- a very young man -- and yet he has a superb eye and begins to question the explanations he's received for why the world was the way it was."
On Feb. 12, the world will celebrate the 200th birthday of the "father of evolution," and to commemorate the occasion, Leroi and the National Geographic Channel retraced Darwin's famed voyage on the HMS Beagle. Using Darwin's diary and countless notebooks as guides, they traveled from South America to the South Pacific, then to the Galapagos Islands and beyond to replicate the journey that inspired Darwin's seminal work.
They discovered that the story often repeated around the dinner table isn't entirely true.
The story goes that Darwin traveled to the Galapagos Islands in the Pacific Ocean and then, upon observing the giant tortoises and finches -- eureka! -- arrived upon his theory of evolution.
But, Leroi said, though that version is a satisfying story, it's not true at all.
"It turns out, if you actually read 'The Voyage of the Beagle' … the idea of evolution came to him very gradually," Leroi said.
Darwin spent only five weeks out of five years in the Galapagos Islands and that was toward the end of his transformational journey.
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