We all live the way we do in villages and cities because a long, long time ago, the early humans gave up hunting for farming. They domesticated plant species by cultivation, ploughed the land and harvested the grain. That was the beginning of civilisation as we understand it.
But, do you know that certain ant species were actually farming fungus years before humans learnt how to farm?
For many millions of years, ants belonging to the attines group were farming and cultivating fungi in their anthill nests. They had actually domesticated various wild fungi!
How did it all begin? The first ant to pick up a fungus perhaps accidentally discovered that the fungi growing on the bits of food were more nutritious than the food itself. The ant then started bringing in decayed leafs to feed the fungus and then to eat the fungus.
Under the attini genera or group there are around 200 species of gardening ants. They are found largely in Central and South America.
The attines are divided into lower and higher categories. The fungus-growing ants come in the lower category while leaf-cutter ants and several others form the higher category.
The lower attines generally have smaller nests with a few hundred workers. They pick up dry and dead vegetation and use it grow their fungus. These include grasses, leaf-litter, the fæces of other insects, and dead insects themselves.
The higher attines, on the other had, actually cut leaves from plants and feed their fungus garden. Their nests are larger, with thousands to millions of workers and they live in intricately designed nests.
Both categories of the attines continue adding bits of fungus to their garden. The fungus growth in the garden may be as small as a golf ball or as large as pumpkins. Within a few weeks, they have fresh mushrooms (mushrooms, too, come in the category of fungus). These are not the actual mushrooms you see under trees, but are fungal tissues which are eaten by the ants.
Just as humans develop new crop strains as the old ones get diseased, ants too gather new crop strains. They do it by going back to the original wild varieties of the crops and experimenting with them. These wild crop relatives help them survive in changing conditions.
After an ant domesticates a fungus, that fungus changes genetically and becomes different from the wild variety. Sometimes the fungus dies or changes its genes, and when the ant disperses it, a new variety is formed. From the number and variety of genetic differences, scientists are able to predict how far back ants have been farming. And they have traced it to 15 million years ago!
The attines and the fungi form a great relationship that is called symbiosis. Each is beneficial to the other. The ants provide food for the fungus, which they can’t eat themselves. The fungi feed on the plant parts, which get converted into proteins and sugars. These are in a form that the ants can eat. Thus the fungus is the attines’ best friend.
Inside the garden, the ants chew leaves to make them softer and speed the growth of the fungus by adding decayed matter that acts like manure. They also weed out any rival fungi that sprout in the garden. Finally, the ants even help disperse the fungi. When a new queen leaves the nest to start her own nest she takes some fungus with her to create a new garden.