The Laboratory Island in the Caribbean Where Nearly 2,000 Monkeys Have Been Observed for 80 Years in One of the World's Largest Live Experiments on Human Behavior

The Laboratory Island in the Caribbean Where Nearly 2,000 Monkeys Have Been Observed for 80 Years in One of the World’s Largest Live Experiments on Human Behavior

Written by Romário Pereira de Carvalho

Published on 10/01/2026 at 22:45

Updated on 10/01/2026 at 22:47

Imagem: Ilustração

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1.6 Km From Humacao, Cayo Santiago Has Maintained A Monitored Colony Of Rhesus Monkeys For Over Eight Decades, Supporting Longitudinal Studies On Behavior, Health, Genetics, And Environmental Impacts Relevant To Science

Located about 1.6 km off the eastern coast of Puerto Rico, near Humacao, Cayo Santiago has hosted a colony of rhesus monkeys for over eight decades, sustaining ongoing scientific research on behavior, health, and social organization, with direct impact on biomedical science.

Origin Of The Experimental Station

The island spans 15 hectares and has been functioning as an experimental station dedicated to the study of primates in a semi-open, monitored environment since 1938.

The project was conceived by primatologist Clarence Carpenter, a pioneer in the study of animal behavior, with institutional support from Columbia University.

ARTICLE CONTINUES BELOW

Population And Genetic Continuity On The Island

Since then, over 14,000 monkeys have lived on Cayo Santiago, forming one of the longest population series ever observed.

Currently, the colony includes approximately 1,800 individuals, organized into 12 social groups, all direct descendants of the original group.

This genetic and demographic continuity has allowed for rare longitudinal studies, with comparisons between generations over successive decades.

Management And Sanitary Protocols

Scientific management is conducted by the Caribbean Primate Research Center, the CPRC, which is responsible for administration and protocols.

The center is funded by the United States National Science Foundation and the University of Puerto Rico, according to institutional data.

Access to the island is strictly controlled, restricted to trained researchers and caregivers, following rigorous sanitary standards.

These rules aim to prevent risks associated with the Herpes B virus, harmless to the monkeys but potentially fatal to humans.

Focus Of Behavioral Research On The Island

The research primarily focuses on social behavior, observing feeding routines, reproduction, hierarchy, alliances, and conflicts.

Institutions such as Harvard University, Columbia University, and Imperial College London participate in studies regularly conducted on the island.

Each animal is individually identified, allowing for the comparison of behavioral data with accumulated genetic, clinical, and nutritional information.

This continuous monitoring supports analyses of aging, stress resilience, and social structure on an unprecedented scale.

Scientific Contributions And Controversies

Over the decades, studies have contributed to research on oral health, hormonal production, and response to infectious diseases.

Monkeys from Cayo Santiago have been used in research that aided in the development of vaccines against polio and COVID-19.

There have also been studies related to dengue and Zika, conducted in laboratories in the United States with materials sourced from the colony.

The organization Peta criticizes the use of primates in biomedical experiments and denounces the sale of animals for research.

The CPRC asserts that all activities comply with United States legislation and international ethical standards, highlighting the scientific relevance of the data.

Impact Of The Hurricane And Current Scenario

The island’s geography changed drastically in 2017 when Hurricane María destroyed about 60% of the local vegetation.

The cyclone eliminated the isthmus connecting parts of the island, dividing the territory into two islets and damaging essential structures.

Despite this, the majority of the monkeys survived, with estimates indicating around 50 deaths following the weather event.

Researchers observed an increase in social cooperation and resource sharing, as well as accelerated biological aging.

Today, Cayo Santiago remains a living observatory of the environmental, social, and biological effects on an intensively monitored population.

With information from Terra.

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Matthew Knepp

#225914

17/01/2026 12:14

Wow, somebody proofread to this article before publishing. Good grief.

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David Carver

#225627

16/01/2026 12:09

I don’t see how this kind of “study” can have any relevance on anything at all. It’s not their natural environment, not even close, and did anyone else notice how run down everything was? If not run down then barren and desolate. They wouldn’t live like that in an ACTUAL natural environment. Monkeys don’t live on the ground out in the open like that. Just seems really evil. Something like that would be considered a form of torture if they were human. Sure, they’re provided food from receptacles. It’d be too openly cruel if they really had to forage on a little lump of land that had no natural resources of it’s own.
We spend untold millions of dollars on feeding and housing rapists, pedophiles and murderers; let’s put a bunch of them on an island and REALLY get to see how humans truly react in a situation like that.
This way PETA won’t have anything to protest and maybe we’ll thin out the human herd a bit.

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Rosalind Buck

#225209

15/01/2026 01:44

Sounds rather like the slave trade. I’m sure it’s fascinating but seems unethical

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The Laboratory Island in the Caribbean Where Nearly 2,000 Monkeys Have Been Observed for 80 Years in One of the World’s Largest Live Experiments on Human Behavior

1.6 Km From Humacao, Cayo Santiago Has Maintained A Monitored Colony Of Rhesus Monkeys For Over Eight Decades, Supporting Longitudinal Studies On Behavior, Health, Genetics, And Environmental Impacts Relevant To Science

Origin Of The Experimental Station

Population And Genetic Continuity On The Island

Management And Sanitary Protocols

Focus Of Behavioral Research On The Island

Scientific Contributions And Controversies

Impact Of The Hurricane And Current Scenario

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Marine fossils found at over 8,800 meters altitude on Everest and in large mountain ranges have proven that entire continents move, oceans disappear, and tectonic plates collide over millions of years, revolutionizing science in the 20th century.

Tourists on Everest were poisoned by guides who mixed substances in food to provoke false symptoms of altitude sickness while helicopter operators and hospitals charged inflated rescue fees to insurance companies.

Few people know this, but Neil Armstrong, one of the most famous NASA astronauts in history, survived the Korean War after jumping from the plane during his seventh combat mission aboard the USS Essex aircraft carrier of the United States.

The first commercial hydrogen-powered ferry enters operation in the U.S., eliminates the use of diesel, uses fuel cells to generate clean energy on board, and transforms San Francisco Bay into a landmark of the new era of emission-free navigation.

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The Laboratory Island in the Caribbean Where Nearly 2,000 Monkeys Have Been Observed for 80 Years in One of the World’s Largest Live Experiments on Human Behavior

1.6 Km From Humacao, Cayo Santiago Has Maintained A Monitored Colony Of Rhesus Monkeys For Over Eight Decades, Supporting Longitudinal Studies On Behavior, Health, Genetics, And Environmental Impacts Relevant To Science

Origin Of The Experimental Station

Population And Genetic Continuity On The Island

Management And Sanitary Protocols

Focus Of Behavioral Research On The Island

Scientific Contributions And Controversies

Impact Of The Hurricane And Current Scenario

At just 14 years old, a boy creates a system without energy, using steel pipes buried in the ground, that irrigates seedlings with moisture from the air, to combat the water scarcity threatening reforestation in northern China.

Where there was only sand and wind at 40 degrees, China built a megacity of 500,000 inhabitants with farms, wineries, and universities in the middle of the desert using melted glacier water from hundreds of kilometers away.

At over 8,800 meters above sea level, the summit of Mount Everest is made up of rocks that originated at the bottom of an ocean about 500 million years ago and were pushed to the highest point on Earth by the collision of tectonic plates.

At over 80° south latitude on Mars, a formation called “Inca City” reveals a network of kilometer-scale ridges that forms an impressive geometric grid visible from space, created by deep fractures and sculpted by ice in one of the most extreme environments on the red planet.

A couple builds a system to bring water from the spring to their land, climbs a hill with materials on their backs, and creates a simple, cheap, and sustainable solution to ensure their own water supply.

Embraer’s flying car successfully takes off in SP, advances towards certification, has already completed 35 flights, reaches 43 meters in height, and promises to operate with much less noise than helicopters.

The end of total solar eclipses has a deadline: the Moon is moving away from the Earth at about 3.8 cm per year, and in approximately 600 million years, it will no longer completely cover the Sun, ending one of the rarest coincidences in the Solar System.

Marine fossils found at over 8,800 meters altitude on Everest and in large mountain ranges have proven that entire continents move, oceans disappear, and tectonic plates collide over millions of years, revolutionizing science in the 20th century.

What if the Sun disappeared suddenly? Simulation shows Earth in darkness within minutes, extreme cold, and rapid collapse of life on the planet.

A 2,400-year-old iron foundry has been discovered in Senegal with 100 tons of slag, 35 furnace bases, and signs of nearly eight centuries of continuous metallurgical activity.

Four humans are flying towards the Moon inside the Orion capsule launched by the SLS rocket, and on April 6, Artemis II will disappear behind the far side of the Moon without communication with Earth for nearly an hour.

Worlds covered by water, atmospheres filled with hydrogen, and the possibility of life beyond Earth: ocean planets are rewriting the map of cosmic search and forcing scientists to rethink where to look.

Marine fossils found at over 8,800 meters altitude on Everest and in large mountain ranges have proven that entire continents move, oceans disappear, and tectonic plates collide over millions of years, revolutionizing science in the 20th century.

Tourists on Everest were poisoned by guides who mixed substances in food to provoke false symptoms of altitude sickness while helicopter operators and hospitals charged inflated rescue fees to insurance companies.

Few people know this, but Neil Armstrong, one of the most famous NASA astronauts in history, survived the Korean War after jumping from the plane during his seventh combat mission aboard the USS Essex aircraft carrier of the United States.

The first commercial hydrogen-powered ferry enters operation in the U.S., eliminates the use of diesel, uses fuel cells to generate clean energy on board, and transforms San Francisco Bay into a landmark of the new era of emission-free navigation.

Diving with a camera in Lake Furnas reveals a submerged city with an entire street, almost intact houses, a preserved bridge, a wood stove, a Kombi, and even a bus at the bottom of the largest lake in the Southeast.