Puerto Rico’s Monkey Island

In 1938, with the support of Columbia University and the School of Tropical Medicine of the University of Puerto Rico, primatologist Clarence Carpenter populated the island of Cayo Santiago with 450 rhesus macaques from India. With its current population of 2,000 primates, Cayo Santiago is popularly known as Monkey Island.

Human visitors, other than the research scientists, are not allowed.

The research begun more than eight decades ago makes this one of the longest-running demographic studies in the world.

The University of Puerto Rico’s Caribbean Primate Research Center was established in 1970, further enhancing the research potential of a unique island.

The beginning

Scientists at the Institute of Tropical Medicine and Hygiene, the forerunner of the University of Puerto Rico School of Medicine, wanted to learn more about tropical diseases. Carpenter got the idea of populating Cayo Santiago with disease-free monkeys for a controlled study of tropical diseases over time.

The scientists observed and tracked the social behaviors of the population. In the beginning, they fed the animals, bringing fruit and vegetables to Cayo Santiago. Over time, the population grew and naturalized.

Scientists from around the world visit Cayo Santiago and use the data gathered there. Studies of primate physiology, genetics, behavior, and population dynamics have been influential in those fields. Research from Cayo Santiago has even changed the way human babies are delivered.

Today on Monkey Island

The Laboratory of Primate Morphology has 3,600 non-primate skeletons and is a rich resource for scientific study. Studies conducted at Monkey Island range from vaccination studies showing the beneficial effects of vaccination programs on populations to diseases of aging.  The Laboratory is home to an extensive genetic and life history database.

As the population rebuilds and resettles after the devastation of Hurricane Maria, researchers are learning about how primate populations respond to disasters. Researchers have seen how social networks changed, and how individuals altered their responses to one another.

At the same time, volunteers are helping to clear up debris and replant forests. The lack of food and shade created significant hardships for the population, but most of the monkeys survived. Research was limited during the time spent focusing on rebuilding. The monkeys also had fewer babies during that time; humans and monkeys alike were focusing their energies on rebuilding.

The COVID-19 pandemic has also limited field work and educational opportunities at Cayo Santiago, but the facility is beginning to reopen and looks forward to welcoming more researchers and students.

Tourists will not be allowed to visit, but they can see the inhabitants of the island by boat.

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