The worms go in, the worms go out

Look at the smile of kinship on the face of any child who finds a worm. It's a fascination that only deepens with age, as evidenced by two new books written by grown-ups. In "The Earth Moved," California gardener Amy Stewart takes us on a subterranean journey with these spineless, blind wonders that eat their way through the soil, destroying toxins, and turning the ground into rich compost for plants and trees.

Even the great biologist Charles Darwin recognized the merit of the earthworm. "It may be doubted," he wrote in 1881, "whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures."

Stewart, who like many gardeners knows a lot about the earthworm population in her soil (including that there are many types of earthworms), wonders why more scientists before Darwin didn't bother to study the tiny beasts. It was Darwin who saw their potential and essentially put them on the map. He realized earthworms had the ability to affect gradual geological changes over centuries that could produce enormous outcomes - action that fitted into his work on evolution. He also projected their impact on a smaller scale: In a typical acre garden, 50,000 earthworms produce 18 tons of manure, or enriched soil, each year.

This peaceful, delicate creature, Stewart writes, has posed a large task for scientists, who have taken more than 100 years to piece together a portrait of the earthworm's dark life. But the subterrestrials still have more to teach us, even as creatures like the giant Oregon earthworm are being pushed to the brink of extinction. In an age when farmland is being paved over to accommodate urban and suburban sprawl, good soil is an increasingly valuable commodity. Earthworms - going about their deliberate business of churning out rich dirt - may emerge as unsung heroes.

Archeologists owe a debt of gratitude to earthworms, too. By churning soil, the little creatures have safely buried ancient artifacts, including coins, stone implements, and gold below the ground.

Stewart, an admitted nonscientist, began her study by making observations of the earthworms in her backyard. Like many gardeners and 6-year-old boys before her, she began keeping a worm bin inside her house to watch over their fascinating activities. They're clean, quiet, well-behaved creatures, she writes, that are interesting to watch, and even beautiful. Stewart offers us an engrossing read with related websites at the end of her book, and directions on how to make your own worm bin.

Andrew Brown isn't a scientist either, but a journalist who tells an intriguing story of how three scientists won the Nobel Prize for their research on the genetic makeup of a nematode worm known as C. elegans, now one of the most studied worms in genetic science.

"In the Beginning Was the Worm" describes how these scientists toiled to unveil the genome of C. elegans, the first multicellular organism on which this was done. Their work is credited by other scientists as leading to the sequencing of the human genome, and the subsequent multibillion-dollar global industry that it spawned.

(One drawback, as in Stewart's book, is a shortage of drawings or photos. Given the interesting subject matter and the authors' enthusiasm, readers deserve to see more than just black type on the page.)

Brown goes to great lengths to examine the history of the study of C. elegans. He also gives a rare insight into the tedious, or some would say passionate, world of scientists who work long hours six days a week for years on end, often for little pay and with little hope of any giant discovery or reward. But one of the three scientists, John Sulston, offers up this bait to aspiring investigators: "When we understand the worm, we understand life."

Four years after he made that prescient comment, he and his colleagues won the Nobel Prize.

• Lori Valigra is a freelance science writer in Cambridge, Mass.