A New Leaf

“Our lives are not our own. We are bound to others, past and present, and by each crime and every kindness, we birth our future.”

―David Mitchell, Cloud Atlas

If you weren’t paying attention, it might have looked as if the ground was moving, an impressionist tableau of tiny brown strokes shifting amid the dirt. You might have even stepped on it: one of nature’s most marvelous feats of evolution, one half of a symbiosis millions of years in the making. There on the forest floor in Costa Rica, a stream of leafcutter ants marched as one—a procession in perfect form, all acting in service of some unseen higher purpose.

Leafcutter ants are often spotted this way, in trains that can stretch up to 100 feet. Other times, their presence can be detected by the destruction left in their wake: serrated leaves, skeletal remnants of what they once were. They create such carnage with chainsaw-like jaws which can vibrate up to 1,000 times per second. The high-pitched vibration this emits even makes the leaves stiffenallowing for easier cutting. In other words, they are natural harvesters.

They then carry the swathes of leaves they have cut down on their backs to the nest, a feat in and of itself; one ant is capable of carrying as much as 50 times its own weight, the equivalent of a human being transporting a car on our back. Despite their size, leafcutter ants are among the strongest animals on earth—small, but mighty. And they are tough in other ways: they are covered in a rare crystalline armor not found in any other species of insects, allowing them to withstand battle and even stave off fungal infections.

Leafcutter ants are so efficient at fulfilling their namesake duties that they can strip a tree bare in just one day, and can account for up to 17% of all leaf biomass loss in an ecosystem. That’s not to say they are all malefic; by pruning the vegetation that grows around them, they elicit new growth. And in building their nests—which can stretch up to 800 cubic feet and contain over 1,000 chambers—they can till as much as 88,000 pounds of soil, stimulating root growth for plants. They take, but they also give back.

This is just one way these creatures embody reciprocity. Long before humans evolved into being, some 60 million years ago, leafcutter ants invented agriculture. Rather than eat the leaves they harvest, they use them as fertilizer to grow fungi in underground gardenswhich in turn feed the ant colony’s young (the adults get their nutrients from plant sap). The ants are so attuned to the fungi that they can sense how they respond to varying food sources and will change their diet. The leafcutters even secrete a specialized enzyme that protects the fungi from harm.

Leafcutter ants confront our ideas of what it means to be individual. The bonds of symbiosis shared with the fungi they farm are so strong that they have even been likened to one leaf-eating body, with the fungi acting as its gut. Their colonies are massive and sprawling, with up to 8 million ants and a diverse set of roles and functions they fulfill—nearly as complex as human societies. And yet they act in unison; scientists have found that the same mathematical principles that govern individual animals also govern such insect colonies. They are many, yet one.

What will it take for humans to interact with our environment in the same way? To cut down only enough for more to grow? To engage with agriculture as a practice of mutually beneficial symbiosis, rather than parasitism? To see our food sources as not separate, but part of us? To listen to their needs as if they were our own? The scale of change needed can feel overwhelming, but it need not all be on any one person’s shoulders. Individually we are strong, but together we can achieve seemingly impossible feats. Perhaps we might even turn over a new leaf.


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