The Intestines of the Earth
In the autumn of 1881, a man in his seventies, already ill for many years, is kneeling in his garden near the village of Downe in Kent.
He has been in poor health for years, his heart is weak, and within a few months he will die, although he does not know that yet. Instead of continuing to refine the great theory that bears his name, he is examining a jar filled with stones and observing how deeply it has sunk into the ground over the past thirty years. Experiment after experiment.
The man is Charles Darwin, and the last book of his life, published only a few months before his death, is not about the origin of species, nor about humans or emotions.
Its title is roughly this: “The Formation of Vegetable Mould Through the Action of Worms.” Forty years of observation devoted to a single, seemingly insignificant creature.
This is also one of the central themes in a book I recently read by one of my favourite writers: the hidden connection between tiny worms, God, and the world we live in. Darwin’s contemporaries were puzzled. Why was the world-famous scientist who had understood the great structure of life spending what remained of his time staring at worms in a flower bed? The answer is that Darwin saw something we are still inclined to overlook: beneath our feet, a silent workforce is labouring without interruption, and much of the world in which we live is their creation.
The soil that passes through them
Aristotle called them “the intestines of the earth.” An earthworm does not simply live in the soil — it eats the soil, consuming its own habitat. It swallows earth, extracts the organic matter from it, and deposits what remains either on the surface or along the walls of its burrows. What it leaves behind is the famous worm cast: crumbly, rich in nutrients, and far more usable by plants than the original soil.
More from less.
Darwin began calculating, and the numbers astonished him. On an English pasture, he estimated that worms bring several tonnes of soil to the surface per hectare every year — enough that, within a few decades, the entire layer of topsoil has passed through their digestive systems at least once.
In other words, the garden in which we stand is nothing more than the collective work of millions of worms, carried out across generations. This is what Darwin saw: topsoil is not simply something that exists. It is the product of a process. It is not just there in the way a stone is there. Someone, something, makes it — slowly, quietly, from below upwards. If earthworms disappeared, the soil would, within a few human generations, become more compact, poorer, and far less capable of growing things.
The bassoon and the piano
Darwin was not satisfied with measuring. He began experimenting, using surprisingly unusual tools to answer surprisingly unusual questions.
Can worms hear?
He took a bassoon and played it close to worms lying on the ground.
Nothing.
Then his wife played the piano while Darwin placed the worms in a container on top of the instrument. This time they reacted to the vibrations — they were not sensing the sound travelling through the air, but the tremors passing through the surface beneath them.
His most fascinating experiment, however, concerned their intelligence.
At night, worms plug the entrances to their burrows with pieces of leaves. Darwin observed how they grasped the leaves and found that they usually pulled them in by the pointed end — in other words, from the direction that made the task easiest.
They were not simply trying at random.
A tiny creature without a brain seemed to have “solved” a problem.
The worm stone.
Darwin placed a flat stone on the grass and, over decades, measured how slowly it sank into the ground as the worms carried soil out from beneath it. The book that grew out of all this became one of the greatest successes of his life — in its first years, it sold more copies than On the Origin of Species.
Where the earthworm is the invader
We have learned that the earthworm is the gardener’s best friend — and in the garden, it really is.
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But imagine a North American forest somewhere around the Great Lakes.
The glaciers of the last Ice Age wiped out all the earthworms in these regions, and for ten thousand years they did not return. The forests there evolved without them.
In these forests, the ground is covered by a thick, loose layer of leaf litter — fallen leaves and slowly decomposing organic matter. Herbaceous plants root in it, insects nest in it, and it nourishes the fungal networks on which the trees depend.
Then the earthworm arrives — usually from anglers’ bait boxes, gardens, or accidental introductions — and it does exactly what it always does:
it eats the leaf litter.
Except that here the litter is not waste.
It is the habitat itself.
Within a few years, the loose carpet of leaves disappears, the soil becomes more compact, the undergrowth retreats, some ferns and woodland flowers disappear, and even songbirds that nested in the low vegetation suffer.
The same behaviour that is a blessing in our garden becomes destruction in an ancient forest.
The worm has not become “worse.”
It simply reveals that “good” and “bad” do not reside in the organism itself.
They reside in the context.
Looking down
We are used to looking upward and forward — toward the canopy, the horizon, the screen.
The earthworm reminds us that many of the most important things that sustain us are neither spectacular nor above us, but below us — and we fail to notice them precisely because they work so reliably.
Like the invisible foundations of our lives.
My second observation is this: be careful with labels.
As soon as we stamp something as “useful” or “harmful,” we stop thinking.
The earthworm is the same creature in the garden and in the forest — the difference lies in the environment. It is worth carrying this reflex with us into situations that have nothing to do with worms: a method, a technology, or a habit is rarely good or bad in itself; almost always, what matters is where it is placed.
Darwin’s final sentences in that book are almost tender. There are few other animals in the world, he writes, that have played such an important role in the history of the Earth as these lowly organised creatures.
A man who had seen the great sweep of life ended by pointing to an earthworm and saying:
this, too, was here all along.
And it mattered.
The next time you see an earthworm dragging itself across the pavement after the rain, it may be worth stopping over it for a moment.
It is not just some random worm on the asphalt.
It is a piece of the Earth’s intestines that has temporarily lost its way — and without it, the soil beneath our feet would not be what it is.
