Ants Heal Themselves When Sick

A team of biologists proved that ants know how to self-medicate, and consume toxic substances to fight fungal infections. 

This finding was made by a team of biologists from the University of Helsinki, which decided to poison healthy ants with harmful hydrogen peroxide to prove the theory. The team wanted to show that a healthy ant would never ordinarily consume the substance, because of its toxicity, and that any consumption in the wild -- post-infection -- was in fact a deliberate act of self-medication.

Source: newscientist