Darwin's Worms

Article excerpt

"The subject may appear an insignificant one," Charles Darwin conceded, "but we shall see that it possesses some interest." Earthworms were the subject, and Darwin's lifelong fascination with them revealed as much about the unique qualities of his mind as it did about the surprising effects of the creatures' subterranean labors.

When I stand on a patch of earth and wonder about the activity occurring underfoot, I'm not alone. Gardeners are inquisitive by nature; we re explorers; we like to turn over a log or pull up a plant by the roots to see what's there. Most of the gardeners I know are, like me, quite interested in earthworms, in the work they do churning the earth and making new dirt. We hold soil in our hands, squeeze it and smell it as if we're checking a ripe melon, and sift it to see what inhabits it. Ask a gardener about the earthworm population in her garden, and I guarantee she'll have something to say on the subject.

It seems strange, then, that most scientists before Charles Darwin (1809-82) didn't consider worms worthy of study. In fact, very little was known about them in the 19th century, when Darwin emerged as a sort of champion of worms, devoting his last book to painstakingly detailed research on their physiology and behavior. The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits was published in 1881. Darwin was an old man when he wrote the book, but the subject had interested him for decades. How could so insignificant a creature as the worm capture the attention of so distinguished a scientist? Darwin knew from an early age that earthworms were capable of far more than most scientists gave them credit for. He recognized, in a way no scientist had before him, that they possessed an ability to bring about gradual geological changes over decades, even centuries. And this notion that the smallest changes could result in enormous outcomes fit perfectly with Darwin's work on evolution and the origin of species.

The story, of Charles Darwin and his worms begins in 1837, when the scientist was not yet 30 years old. He'd just returned from a trip around the world on a British sailing ship called the Beagle. He had been offered passage because the captain, Robert FitzRoy, wanted a gentleman on board to share his table. The ship was to travel to the coast of South America, where Darwin would have ample opportunity to do the work of a naturalist, collecting specimens and recording his observations. Young Darwin could not resist the opportunity. He'd been trying to find a way out of the career path his father had laid down for him: parson in a country parish, where he would have plenty of time to chase butterflies and beetles between his duties to the parishioners. It was not the ideal career for the man who would come to be known as the father of evolution; as one biographer put it, "There was, needless to say, the small matter of his faith." A journey around the world would defer the choice of a career for a while, and his father agreed to the expedition. But once on board the Beagle, Darwin realized that the experience would not be the idyllic adventure he had hoped for. The crew encountered more than its share of dangerous weather, the captain suffered some sort of breakdown midway through the voyage, and Darwin himself was often sick and discouraged. Still, he worked steadily, collecting artifacts and taking notes.

He was away from England five years, longer than he could ever have predicted, and he returned with a greater number of new discoveries than he could ever have imagined. He arrived in port with more than 2,000 journal pages, 1,500 preserved specimens, and nearly 4,000 skins, bones, and dried specimens. It would take years for him to organize the lot of them, and even longer for him to realize the full impact of what he'd collected. In this great array of fossils, insects, and bird skeletons he would begin to see the patterns that would suggest to him a theory of evolution. …