Humans aren't the only ones who domesticate other species. Ants have been 'herding' aphids for millions of years!
Aphids are tiny insects and though considered pests by farmers, they are very useful to ants. Armed with soft bodies, long, thin legs and sucking mouth parts called stylets, aphids feed on the vast quantities of watery sap from plants. The most important part of this diet for the aphids is nitrogen. Carbohydrates, in the form of sugar, is of less use to them and so, is excreted.
Ants that breed aphids, feed on this excreted sugar-rich fluid.
In this mutually beneficial relationship, the aphids benefit from the ants' protection from predators and the ants get easy meals. Some ant species even provide shelter to aphid eggs in their own nests and feed the young aphids until they are grown up enough to suck plant juice on their own.
Humans aren't the only ones who domesticate other species. Ants have been 'herding' aphids for millions of years!
