The Ants That Invented Farming

The story

Deep in the forests of South America, a little parade is marching. Ants, thousands of them, in a line that can stretch further than you could throw a ball, and every single ant is carrying a piece of green leaf held high over its head, like a tiny sailor carrying a great green sail. They are called leafcutter ants, and up in the trees, their sisters snip the pieces from leaves with scissor jaws.

Watch them march, and make a sensible guess: all those leaves must be their food.

Sensible, but wrong. Leafcutter ants do not eat the solid leaves. The workers sip some of the sweet leaf juice as they cut, but the leaf pieces themselves are not dinner. The leaves are... GARDENING supplies.

Follow the parade home, down a hole into an underground city, and what a city: a big leafcutter nest can hold millions of ants, in countless chambers and tunnels they dug themselves. And in the heart of the city lie the gardens. Room after room holds something that looks like grey, crumbly sponge. It is a fungus, a living relative of the mushrooms, neither plant nor animal. THIS is the colony's crop and its great food store. The fungus feeds the ant city, and for the growing young, it is practically the whole menu.

Now the leaves make sense. The ants chew the leaf pieces into soft mulch and feed the mulch to the fungus, exactly the way a farmer spreads food into the soil for the crops. And the ants do not stop at feeding. They are complete, careful farmers. Gardener ants patrol the fungus shift after shift, licking it clean. They pull out the wrong kinds of mould, the weeds of the garden, and carry rubbish away to dumps kept well apart from the crop, underground chambers in some colonies, waste heaps outside the nest in others. Some ants even carry helpful germs on their own bodies that fight off garden diseases, like a built-in medicine for the crop. Tiny guards even ride on the marching leaves, protecting their big sisters as they walk.

The fungus, in return, grows special swollen tips, little parcels of food, that the ants harvest and feed to the city, especially the young. The ants cannot live without their crop, and this fungus has never been found living wild on its own. Its home is the ant gardens. When a young queen flies away to start a new city, she carries a tiny crumb of the family fungus in a pocket in her mouth, a starter for her first garden.

And their farms are far, far older than ours. Scientists say ant farming began tens of MILLIONS of years ago. People have farmed for roughly twelve thousand years. The ants beat us by an almost unimaginable stretch of time.

So the next time you see any ant hurrying along with something held high, give it a respectful nod. Some of its cousins are farmers, with crops and weeding and fresh leaf mulch, running some of the oldest farms on Earth, in the dark, right under the forest floor.