In 1974, researchers from the US nonprofit blood bank, the New York Blood Center (NYBC), opened an experimental laboratory on the west coast of Liberia. Working with the Liberia Biomedical Research Institute, they trapped wild chimpanzees and used them to conduct research and drug trials.

The animals were kept outside the capital, Monrovia, confined in cages like these at the Vilab II research facility. Researchers infected them with various diseases, such as hepatitis B and river blindness, an eye sickness caused by a parasite, so they could study the effectiveness of different treatments.

The total population was 85 chimpanzees. However, work at the research laboratory was disrupted during the two Liberian civil wars in the 1990s and early 2000s. In 2005, the facility was closed for good and the apes were gradually relocated to six uninhabited islands in the Farmington River estuary. Today, animal rights activists go out regularly by boat to ensure the animals are fed.

Staff from the Humane Society regularly bring buckets of fruit and drinkable water — both are scarce on the islands. Although it pledged to pay for the chimps' care for the rest of their lives, the NYBC cut this funding in 2015. After an outcry, it gave another $6 million (€5.3 million) in 2017 — not nearly enough, said the Humane Society. On average, chimps can live some 30 to 40 years.

The colony currently numbers around 65 apes, including babies. They often react aggressively when people approach their island. Strangers to the animals may be splashed with water or screamed at. The alpha chimps keep a close eye on everything. Releasing the apes elsewhere would be too risky, especially for other animals, because they still carry infectious diseases.

As chimpanzees are not naturally able to swim, they never venture very far into the water. The volunteers bringing the food wear protective clothing and maintain a safe distance. Only a few of the animal welfare workers have established a close bond with the apes over the years. Once the chimps have gotten hold of their fruit, things are a bit more relaxed.

The research conducted by NYBC on the chimpanzees led to successes: It contributed to the development of a hepatitis B vaccine, and a diagnostic procedure for hepatitis C. But in an interview in 2014, Betsy Brotman, the researcher who was in charge of the lab until 2005, said: "The animal rights activists were right. Chimpanzees really shouldn’t be used in experiments. I really do feel this way."

Researchers observed how an orangutan in Indonesia treated itself with a medical plant. The great ape chewed the plant, applied its juice onto the wound and used its leaves as a plaster. Within a week, the wound had healed. The plant, known locally as Akar Kuning, is used as a medicine by people in Indonesia.

Animals use remedies found in nature to take care of wounds or get rid of parasites. The process of animals healing themselves is called zoopharmacognosy. Researchers have observed chimpanzees in Gabon, West Africa, treat their wounds — just not with plants.

Several chimpanzees in Loango National Park, the researchers noted, caught insects in the air, squeezed them between their lips and then applied the insect to open flesh wounds. What stood out — they didn't just treat their own wounds, but also those of other chimpanzees, as seen here. This suggests that the primates are capable of pro-social behaviors that benefit others.

The American black bear knows about the healing powers of the osha root. Biologist Shawn Sigstedt, who observed the animals in northern New Mexico, found that they use the root to treat their arthritis pain. He says the region's Indigenous people first learned about the root's healing powers from the bears after observing them use the plant hundreds of years ago.

If you own a dog, you've seen self-medication in action. Dogs eat grass when they have an upset stomach. They'll usually vomit it back up or excrete it undigested shortly after ― for them, the grass is a way to get rid of pathogens or parasites.

Researchers are aware of more than 200 bird species who like to sit in anthills and make bathing-like movements with their wings to attract ants. Through this process of "anting," the birds cover themselves with formic acid, which rids their feathers of microorganisms like fungi and bacteria.

Pregnant lemurs in Madagascar nibble on bark and leaves from fig and tamarind trees, which contain components that help with the lemurs' milk production, kill parasites and increase the chances of the animal giving birth successfully.

An elephant is pregnant for 22 months ― longer than any other animal. No wonder they're ready to get the baby out by the end of that! In Kenya, heavily pregnant elephants were seen deviating from their usual routes to chomp on trees from the boraginaceae family, and then giving birth shortly after. Kenyan women also use the plant to induce birth.

Along with self-healing, animals also turn to Mother Nature for intoxication. Reindeer in Finland and Siberia get high by eating Amanita muscaria, also known as fly amanita. Shamans of the Sami people used the hallucinogenic mushroom when herding the reindeer, allowing them to reach a prophetic trance in which they said they could communicate with the animals.

While filming a BBC documentary, researchers observed dolphins "playing" with a puffer fish, nudging it back and forth between them for up to half an hour. The puffer fish was spared, unlike the fish caught as prey, which the dolphins tore into quickly. The puffer fish, under distress, released a toxin that put the dolphins into a trance that saw them drifting just under the water's surface.