Puerto Rico's Monkey Island Lures Scientists For Generations The isle of Cayo Santiago has been home to at least nine generations of rhesus monkeys since the colony's founding in 1938. Primatologists here seek clues to primate kinship, cognition and ecology.

Puerto Rico's Monkey Island Lures Scientists For Generations

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Imagine you're on a tropical island in the Caribbean - coconut trees, rocky cliffs, blue-green waters and hundreds of monkeys that have a disease that could kill you. What you're picturing is a real-life island off the coast of Puerto Rico. NPR's Anders Kelto went there.

ANDERS KELTO, BYLINE: It's sunrise and a group of scientists are climbing into a boat. They're wearing khaki shorts and boots. Some have backpacks. Someone fires up the engine, and the boat begins to cross a calm channel of water. Up ahead, I can see the island - steep cliffs, lush green trees. The boat docks, and as we get out, we scrub the soles of our shoes with a brush - dip them in this pink disinfecting liquid. We step onto the island, and right away, I hear this sort of spooky grunting noise.


KELTO: I can't tell where it's coming from, and then, up in a tree, I see two beige monkeys looking down.

GISELLE CARABALLO-CRUZ: Just be careful they don't pee on you.

KELTO: That's Angie Ruiz. She's part of a team of researchers from the University of Puerto Rico who manage this island, called Cayo Santiago. Ruiz actually has one of the best job titles ever - monkey island census taker. But her warning about not getting peed on is serious. These monkeys naturally carry Herpes B, a virus that can be deadly to humans. So, rule number one on Cayo Santiago, don't get peed on by the monkeys. [POST-BROADCAST CORRECTION: In the audio of this story, the person identified as Angelina Ruiz-Lambides is in fact Giselle Caraballo-Cruz. The Web version and name identifiers in the transcript have been corrected. Because NPR transcripts reflect what was said on the air, there are references to "Angie Ruiz" and "Ruiz" on this page. In each case, that's what correspondent Anders Kelto said. Those were mistakes. He should have said "Giselle Caraballo-Cruz" and in later references, "Caraballo-Cruz."]

We walk along a dirt path, toward a large metal cage. It's where the scientists eat lunch.

CARABALLO-CRUZ: So, we have our resting areas, our eating areas. We're the ones in the cages, and the monkeys are free.

KELTO: It's like a zoo where the monkeys come to see the humans.

CARABALLO-CRUZ: Exactly, and they can see us eating.

KELTO: (Laughter) Rule number two, the monkeys are the free ones. But it's not time for the humans to eat just yet, so we keep walking up a steep hill. Ruiz spots a small monkey off the side of the trail, and suddenly she veers way to the left, and she gestures at me to follow.

CARABALLO-CRUZ: If you see a baby running around on the road, stay away from it 'cause chances are, mom's around and...

KELTO: And she's protective.

CARABALLO-CRUZ: Oh, yeah, and they come out of nowhere.

KELTO: But, she says, if you see a male monkey, don't be intimidated because the males like to mess with people. Recently, she says, there was a researcher - a college student - who let a monkey bully her.

CARABALLO-CRUZ: The monkey would actually chase her. Eventually, she like - I told her, grab a rock, show them the rock, and they'll know what happens after you show them the rock. And they'll stop picking on you. And eventually, then they all stopped picking on her.

KELTO: And that's rule number three of Cayo Santiago, stay from the babies, but show the males who's boss.

We get to the top of the hill and the view is spectacular. The mainland of Puerto Rico is behind us, open ocean in front. A white pickup truck drives past and some men get out and unload big white bags of monkey chow. It looks like dog food. And suddenly, there are monkeys everywhere.


KELTO: They're coming down from the trees and walking right by our legs to get to the food, and monkey fights are breaking out all around me. My heart is totally pounding. And in this chaos, a researcher named Sean Coyne is just calmly walking among the primates.

Hey, can I walk with you while you work?


KELTO: It's not too distracting?

COYNE: Not at all.

KELTO: OK. So, can you tell me what you're doing?

COYNE: Right now I'm just looking to collect fecal samples to analyze for hormones. The morning's the best time. When they first wake up, they all tend to go to the bathroom when they first move.

KELTO: Coyne is a grad student at the University of Chicago and spends a lot of time on the island. He's studying how hormone levels affect monkeys' sexual development. He says that translates into a lot of time scooping up monkey poo.

COYNE: Yeah, my mom's so proud. But, all in the name of science.

KELTO: The work here isn't glorious and it can be dangerous, but a lot of important science on primate behavior has happened here over the years. And coming here is sort of a rite of passage for many biologists. The island is the oldest wild primate research center in the world. It was created in the 1930s. Back then, biologists were spending a lot of time chasing monkeys around the jungles of Asia and Africa. The idea was to make things easier by putting the monkeys on a small island closer to the U.S.

RICHARD RAWLINS: Where the animals were always there could easily be accessed and large amounts of data could be collected within a short amount of time.

KELTO: That's Richard Rawlins, the former director of research on Cayo Santiago. He says about 500 rhesus macaques were brought here from India in 1938. It was a mission with a lot of challenges. About 50 monkeys, he says, died at sea during a 47-day voyage. And the scientists didn't really know how to set up the island before the monkeys arrived.

RAWLINS: They planted fruit trees with the naive idea that these trees would be sufficient to sustain the monkeys, and they wouldn't have to buy food for them.

KELTO: But, he says, that didn't work out well.

RAWLINS: The monkeys, once on the island, had been eating this hulled rice for 47 days, instantly went over and vaporized all the stuff that had been planted (laughter).

KELTO: So, scientists had to feed the monkeys. But for long stretches of time, there was no money. Many animals died of starvation and malnutrition. But Rawlins says, a few dedicated researchers helped the colony survive. Angie Ruiz, the monkey census taker, says today the colony faces a different threat.

CARABALLO-CRUZ: People coming on the island without permission and having tuberculosis or having any illnesses that they can transmit to the monkeys.

KELTO: She says people sometimes sneak tourists onto the island. And fishermen come here to catch hermit crabs. Ruiz says, if any of those visitors transmit a disease to the monkeys, it would move incredibly quickly through the whole colony. And on top of the risks to the monkeys, she says, these people are putting their own lives at risk.

CARABALLO-CRUZ: It's dangerous to come out here and if you don't know the protocol, if you don't know what to do if you get an exposure, you could get sick.

KELTO: Or you could die, she says. But there's a problem. The researchers can't legally prevent people from coming on shore.

CARABALLO-CRUZ: The problem we have is that anything the water touches is public property.

KELTO: The government has proposed a bill that would make the island a private research facility, open only to scientists. But the bill hasn't yet passed. So, the researchers just keep hoping that everyone - monkeys and humans - stay healthy. Anders Kelto, NPR News, Cayo Santiago, Puerto Rico.

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