Have you ever seen your cat or dog eating grass? They do so because it can help their digestion, and many wild species use natural substances to prevent and control diseases. This is called "zoo pharmacognosy" or, more commonly, animal self-medication.

Scientists have discovered that tamarin monkeys use a specific tree resin (树脂) as medicine. In the Brazilian Atlantic Forest, scientists followed several groups of them to collect data. During one of these daily studies, tamarin monkeys were observed rubbing their bodies on the trunk of a tree. At first, researchers thought that they were marking their territory, a common behaviour in this species. Botanical experts later confirmed that the tree was a species of cabreuva, which is well known for its medical properties.

Researchers decided to place camera-traps in different sites at the foot of the tree to record future visits by tamarin monkeys. The records surprisingly showed that many animals living in the forest visited it. Totally, ten species were observed. For many of them, it was the first time that behaviors similar to self-medication had been observed. More surprisingly, one species spread resin on each other's fur in pairs. In general, the species seemed to specifically visit the tree to acquire the resin and seemingly benefit from it, either healing their wounds or fighting back parasites (寄生虫).

While further studies are needed to identify the properties of the resin and thus confirm that this is indeed self-medication, the use of it suggests that cabreuva represents a common and universal drugstore for the residents of the Brazilian Atlantic Forest. It is likely to be a valuable resource helping the species maintain their magnitude by improving their health.

This discovery could have an important protection influence, as the disappearance of some trees could potentially affect the survival of some animals.