Summary
Some ants carry leaves not to eat them, but to feed fungus gardens. The colony grows the fungus and harvests it regularly.
Watching an ant carry a leaf fragment can look funny. But that leaf is not for one ant, it is part of a colony scale farming system.
Leaf cutter ants chew leaves into a nutrient base for a specific fungus. The fungus grows, and the ants get most of their food from it.
It is a mutual partnership: ants protect, clean, and spread the fungus, while the fungus provides steady nutrition. Division of labor inside the colony resembles organized agriculture.
This shows that farming is not only a human invention. In nature, sustainable production and care can be far older.