Some ants cultivate a crop they cannot live without

Leafcutter ants do not eat most of the leaf fragments carried underground. They use them to grow a particular fungus, tending gardens that convert plant material into food the colony can use. The insect-fungus partnership is agriculture in a precise biological sense: cultivation, maintenance and dependence evolved long before human fields.

Calling it farming is an analogy based on observable husbandry, not a claim that ants plan as people do. Relationships also vary among ant and fungal lineages, with parasites and microbial partners adding further layers. The startling bounded fact survives: a green procession across a forest floor may be transporting substrate for an underground crop.