In the new science of zoopharmacognosy, scientists patiently watch animals to learn about how they medicate themselves. In the most profound case, chimpanzees who are not feeling well seek out a plant called aspilia and eat one of its leaves whole. Upon studying this plant, scientists have found a chemical in it that is a strong antibiotic which may even reduce some cancers. Elephants and bears also treat themselves pharmacologically.
See also: Do Animals Feel Pain?