Our ancestors developed agriculture about twelve thousand years ago. As they harvested the first crops, they undoubtedly congratulated themselves on their cleverness—after all, cultivation is far more efficient than hunting and gathering. Little did they know, however, that humans were not the Earth's first farmers. Certain species of ant have been practicing agriculture for millions of years.

One example is the parasol ant of South America. The workers of this species clip large quantities of leaves from the forest and bring them back to the nest. These leaves are not eaten by the ants, but buried in a huge complex of underground chambers. As the leaves turn to compost, the ants seed them with their favorite type of fungus. They tend this fungus crop with great care, even weeding it to get rid of less desirable species. After a while, the fungus is harvested and eaten.

Planting and harvesting is one thing, but what would a real farm be without farm animals? Actually, humans are second to ants in this respect too. Several species of ant domesticate a kind of insect called an aphid. Aphids are good at sucking nutritious juice out of plants. In fact, they're so good at it that they often suck out more than they can digest. The extra juice is secreted out the back of the aphid, where an ant can milk it like a farmer milking a cow.

This is a symbiotic relationship, and in exchange for the nutritious juice the ants protect their aphid flocks from predators. Some species even bring the aphids' eggs into the safety of their own nest, and feed the aphid young until they are ready for grazing.