Man is But a Worm
When we hear the name Charles Darwin, most of us reflexively think of his landmark treatise on evolution published in 1859 and entitled "On the Origin of Species by Means of Natural Selection." But how many are aware of another of Darwin's books entitled: "The Formation of Vegetable Mould Through the Action of Worms With Observations of Their Habits"?
This book, published in 1883, describes in meticulous detail the feeding, burrowing, and casting (i.e., defecation) activities of earthworms. With great analytical insight, Darwin calculates the tonnage of soil turnover per acre that worms bring about and he speculates on the long-term effects that these activities have on the physical appearance of the landscape. "I was thus led to conclude," he writes, "that all the vegetable mould over the whole country has passed many times through, and will again pass many times through, the intestinal canal of worms."
In the book's final paragraph, he concludes, "The plough is one of the most ancient and valuable of man's inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earthworms. It may be doubted 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." Such notions, in those days, were quite provocative, for many of Darwin's contemporaries believed that worms were generally harmful to plants and, accordingly, should be eradicated.
To Darwin's astonishment, his worm book was incredibly popular, with more than 3,500 copies sold. In fact, he complained of being "plagued by endless streams of letters on the subject." Ironically, his final wish - to be buried in the soil of his adopted village where he could have made a posthumous and material gift to his beloved earthworms - was never granted. Instead, he was entombed within the well-mortared floor of Westminster Abbey.
Nearly a century and a half later, and with the benefit of results from innumerable ecological studies throughout the world, we now have a much deeper appreciation of the remarkable benefits that worms provide in enhancing soil fertility. We have begun to understand the extent to which they break down soil particles and organic matter, turnover and mix soil layers, form soil aggregates, and enhance soil porosity, drainage and aeration.
In addition, we know, all too well, the disastrous impacts that so many agricultural pesticides can have on earthworm populations. And, after years of ecosystem abuse and misuse, we discovered and ameliorated some of the insidious, secondary effects that pesticide accumulation in earthworms can have on their predators, especially many species of birds. Nevertheless, comparable threats remain on a global scale. Consequently, there are continuing needs for basic research on earthworm ecology and for vigilant monitoring, on a global scale, of the integrity of soil ecosystems.
C. Drewes 2005 home>