Read the full article at The Conversation.

“00O made it!” There was some news to celebrate on Sept. 28 in the email chain of scientists who work at the Cayo Santiago Field Station. Cayo Santiago is a 38-acre tropical island off the coast of Puerto Rico and home to approximately 1,500 rhesus monkeys, earning it the local nickname “Monkey Island.”

Each monkey on the island is assigned a unique three-character ID, which soon starts to feel like its name. Monkey Zero-Zero-Oh is a female we sometimes called “Ooooo.” She is now an old lady in monkey years, beloved for her spunky personality, and we had just gotten word that she survived Hurricane Maria.

The Cayo Santiago Field Station is the longest-running primate field site in the world. Since it was founded in 1938, generations of monkeys have lived out their life with humans watching. Only monkeys live on the island; people take a 15-minute boat trip every day from Punta Santiago on Puerto Rico’s east coast.

Over the past 80 years, an amazing diversity of research has taken place on Cayo. Some scientists, like myself, study cognition. My students and I analyze how the monkeys think and solve problems. Do they follow where others are looking to find out what they see, as humans do? (Yes.) Can they reflect on their own knowledge to know when they don’t know something – a hallmark of human reasoning? (Surprisingly, yes!)

Other scientists observe the monkeys’ interactions to learn which ones are friends, which ones get into fights and who has many suitors. Researchers have tracked these animals’ genes, their hormones and their skeletons after they die. We know who their parents are, how they treat their children and, ultimately, their fate.

Rhesus monkeys on Cayo Santiago before Hurricane Maria. Alexandra Rosati, CC BY-ND
The huge amount of data on each individual monkey’s life, death and contributions to the next generation allow scientists to ask questions in biology, anthropology and psychology that can’t be answered anywhere else. This microcosm of monkey society opens the door onto these highly intelligent and social primates’ lives – thereby allowing us to better understand our own.