For 25 years, Susan Perry has been climbing, crawling, slashing and sloshing her way through the Costa Rican dry forests of Lomas Barbudal in an unprecedented study of the capuchin monkey — a small, white-faced primate that populates large areas of Central America.

Her Monkey Project is one of the longest continuous studies of a single species of monkey in the history of primatology. And what science knows today about the behavior of this monkey, and the conclusions that can be applied to other species, can be credited largely to her and the dozens of primatologists who have studied under her.

There is little glamour in this work. Perry’s geographic research area initially was set aside by the Costa Rican government as a killer bee reserve. The fieldwork Perry and her team must conduct daily to collect data on the monkeys requires trekking through dense forests, running from wasps, crossing rivers, crawling under electric fences, and battling suffocating heat and torrential downpours.

But for Perry, there’s no place she’d rather be, no work she’d rather do, and no research more significant. Her meticulous collection of data has revealed a complex social structure among the capuchins that has redefined scientists’ understanding of the way intelligent animals communicate, learn and survive.

“I spend more time with monkeys than I do my own family and, yes, it’s just hard work,” she says. “I’m always wet, chewed on, or stung. But it’s fun getting up and knowing that I’m going to see something new every single day. These monkeys are amazingly flexible animals, and part of it is that I want to see what they are going to do next.”

In the Jungle: Chapter 1

April 4, 2003, was hot and bone-dry. Sections of the forest were burning — a growing problem in an area increasingly susceptible to climate change and human interference.

On that Friday, Perry’s two-person teams were following two groups vital to her research — one nicknamed “Abby’s group” and the other, “Rambo’s group.”

It was a typical morning, except for the fire nearby. Abby’s group — a 36-member clan named after the since-deceased female in charge when Perry first began her study — was resting and playing in their favorite spot: a quasi-island formed at the intersection of two small rivers. Rambo’s 38-member group was slowly but intently moving upstream, searching the forest for bugs and fruits.

Observations of both groups have led to groundbreaking discoveries on the behaviors of the capuchin — and catapulted Perry into the position of a leader in primatology. Abby’s group has been the cornerstone of her research since she set up her field site in 1990 in this remote region just outside the small city of Liberia. It was this group of monkeys that gave Perry her major breakthrough — that capuchins invent games, and that these eventually become rituals that are passed on through generations.

Over the years, she has discovered that each group has its own unique set of exercises — hand-sniffing, eye-poking, sticking fingers in one another’s mouths — all with the purpose of making bonds, establishing alliances and testing relationships.

But every new piece of knowledge is obtained through grueling work. Perry does not tag the nearly 250 monkeys in her research portfolio — it would be too traumatic for the animals — and so every face must be memorized, every scar documented, every movement recorded. When the monkeys wake up high above the forest each day, researchers must already be present, and they must follow until the sun sets and the capuchins settle in for the night.

Because of this meticulous research, Perry can explain the dramatics of every capuchin she has studied in scrupulous detail — from a monkey’s siblings, parents and grandparents to its victories and defeats. And because the honor of naming a monkey falls on the researcher who first discovers it, a typical retelling of a monkey’s life story invokes the names of literary legends, historical powerhouses and Hollywood superstars.

This April morning started no differently than other punishing mornings. Perry’s team woke up around 3:30 a.m. and — snake leggings wrapped around their ankles, EpiPens in the pockets of their cargo pants, and backpacks stuffed with enough water and food to last 12 hours — spread out to find Abby’s and Rambo’s groups before the sun rose over the forest.

Perry had her usual two cups of leche con café (a lot of milk, just a little coffee), and headed to give a talk to a local community group as part of the Monkey Project’s conservation aspect, which educates residents on the importance of the capuchin. Her four research assistants spent all morning collecting data so precise — recording each time the animals eat, scratch, squeak and squeal — that the detailed retelling of this story 12 years later is possible by merely pulling up a spreadsheet.

There were no signs that the dramatic events about to unfold would have effects that are still felt more than a decade later.

Adventures in Primatology

It was music, not the outdoors, that surrounded Perry as she grew up. She mastered the violin years before ever holding a compass. Perry’s father, a classically trained violinist, and her mother, an equally talented pianist, were early proponents of the Suzuki Method, which calls for music training to be not only rigorously encouraged, but routinely practiced.

They made sure their children were indeed well-trained — and it worked. Perry’s brother, David Perry, is now concertmaster of the Chicago Philharmonic Orchestra.

But for his older sister, monkeys sounded sweeter than violins.

Perry’s love for animals steered her toward veterinary medicine, but she quickly discovered that behavior was more appealing than physiology. While pursuing her doctoral degree in anthropology at the University of Michigan, she decided to study the capuchin because, she says, “It’s the brainiest monkey.”

“It was love at first sight,” she explains, referring to the first time she saw a capuchin. “And I knew that with the capuchin, there would be plenty of puzzles to solve.”

She settled on Costa Rica because of the political stability it offers compared to most other nations with wild monkey populations. She established her field site in a remote section of the country, among vast farmlands and nature reserves.

“Primates don’t live in convenient places,” she says. “Looking back, I’m not sure this location was the best one. The terrain is much more difficult to study in than other locations in the country. But I always knew it was going to be hard.”

Along with her husband, also an anthropologist, she landed in Costa Rica and, without knowing any Spanish, began the arduous task of building a second home and launching her career.

“I had only gone camping once before,” she says. “When I first arrived, I had to go about finding monkeys, using a machete, finding my way around. And I’m a terrible navigator. I get lost in cities.”

When her daughter, Kate, was born, Perry immersed her in Costa Rican culture — and monkey research.

“She was quite portable,” Perry says.

For the past 25 years, Perry has built a community of monkey lovers, not just the research assistants who come from across the world to help her in her discoveries — but also local residents who have become part of her team and her family. She has made such a presence for herself in the region that she is simply known as la monera — the monkey woman.

In the Jungle: Chapter 2

It’s 11:18 a.m. on that blistering April day in 2003. The two large and powerful groups of capuchins — Abby’s and Rambo’s — are headed for a collision.

Porthos is the first from Rambo’s group to come upon the playing monkeys along the two rivers. An unsuspecting Abby group member named Thornhill clashes with Porthos.

A fight ensues. Screams ring out across the forest.

Porthos is calling for help. Thornhill is warning his allies.

Several other males from the incoming Rambo group — Barbell, Tranquilo, Pablo and Moth — come to Porthos’ aid.

Thornhill, defeated, is chased away — never to be seen again.

Once the bulk of Rambo’s group arrives, the three dozen monkeys in Abby’s group, caught off guard, scatter in different directions.

“Dozens of monkeys were spread throughout the forest,” Perry recalls.

Abby’s group is decimated, broken apart and lost.

Adventures in Primatology

Today, Perry and her researchers stay on property lent to the Monkey Project by a local sympathizer, the son of a former Costa Rican ambassador to the United States. The farm is about 40 minutes from the nearest airport, accessible only by a dirt road and neighboring a protected forest reserve.

The team is split between a house that sleeps four and a hangar, affectionately called the bodega, where the more seasoned scientists sleep in tents. The nine current residents rotate fieldwork — two days on, one day off. On their off days, they edit their data, catch up on email, phone calls and laundry, and cook for the team following monkeys.

This is the latest in a series of homes for Perry’s research. It wasn’t always so cozy.

“We used to live with pigs,” she says.

Enter Seidy Rosales, whose father let Perry stay on their rice farm in the 1990s. Rosales, a local native, befriended Perry soon after the recent graduate arrived in the country with her husband. Rosales’ father owned land in the heart of Perry’s research area and invited the young scientists to headquarter their project on his land. The catch: no electricity or running water. And the tents were set up next to where some pigs slept.

“We’d be sleeping right up against the pigs and have to punch them through the wall of the tent when they rolled over on us,” Perry says.

But it was home. And there, Rosales and Perry spent the evenings trading recipes, practicing Spanish and perfecting the Costa Rican tortilla. “We helped her because she didn’t know anyone,” Rosales says.

“We Costa Ricans are always helping people who don’t know our country or our culture.”

It’s a philosophy that is underscored by the many people who have coalesced around Perry and her project, from the cab driver who has loyally ferried her team across the backwoods, dirt roads and mud pits for the past 15 years, to the park service staff who have come to rely on her expertise to keep their piece of nature safe and healthy.

Says park ranger Manrique Montes: “Doña Susan,” as she’s respectfully referred to, “is our compañera de lucha,” or sister-in-arms.

“We don’t consider her just another foreign researcher,” he says. “She’s part of our team. She’s helped us understand how the reserve works and how the monkeys are a key part of its health.”

In the Jungle: Chapter 3

Abby’s splintered group spent much of April 2003 lost in the forest, longing to return to their group life.

Capuchins live in groups ranging from as small as five to as large as 40. Their social structure is complex, based on trust, power, lust and greed. And at the top of each group is a strong alpha male, always plotting, building alliances and, most important, mating. If the alpha remains in power long enough, Perry discovered through her study of Rambo’s group, he eventually allows others to start mating in order to avoid inbreeding.

The melee that destroyed Abby’s group changed the forest’s delicate dynamic and introduced new characters into this 25-year-old soap opera. Jester and Tattle, two low-ranking females tired of being bullied, led their descendants to form a leaner group, which researchers nicknamed “Flake’s group.”

Leaderless and in need of an alpha male, this group turned to some new characters. Four brothers in search of a group to lead, “determined to conquer the world,” as Perry describes them, stumbled upon the newly formed Flake’s group in October 2003. Once the brothers had secured their control over Flake’s group and driven off all of their enemies, they turned on one another. William Shakespeare couldn’t have written it any better.

There was betrayal. Deceit. Exile. The sole survivor and new leader of Flake’s group, Heinrich, had come from a family of 27 paternal siblings when he set out with his brothers to make his own mark on the forest. He was strong, smart and resourceful —just what Flake’s group needed from a leader.

Heinrich held power for four years before being deposed in a bloody confrontation with one of his own group members, Quixote. The two fought so fiercely that Heinrich suffered injuries that deformed his face. Although he lost the battle and his throne, he survived, and today he’s seen as the group’s elder statesman — a proven leader who still protects his group.

While the battles were stressful for Perry and her team to watch, there was a valuable discovery to be made: For capuchins, blood is thicker than water — as long as it’s convenient. The battles for power that ensued after the collapse of Abby’s groups proved that monkeys related to one another stick together and defend one another against foes.

New discoveries are still emerging, thanks to Flake’s group. Currently, Brendan Barrett, a doctoral student under Perry’s supervision, is using the group to examine whether and how the capuchin can transfer knowledge to a fellow monkey. The experiment currently under way exposes them to a fruit that is difficult to open; once one monkey has unlocked the fastest way to break into the center, the researcher documents how that technique is spread among others in the group.

“There’s always a new mystery,” Perry says. “These monkeys are so complex that we’ll never be done understanding how they function.”

Adventures in Primatology

The researcher family that has developed through the Monkey Project is now spread throughout the world.

There have been at least six “Monkey Project weddings” — researchers who have met during their fieldwork and fallen in love. Facebook groups have sprung up. Email blasts keep everyone in touch. And monkey drama is shared and devoured by project members throughout the world.

Perry’s biological family is not to be left out. Her husband and daughter, now 16, still come to Costa Rica every summer. And the Perry music tradition lives on. Primatologist and daughter now play violin duets in local restaurants and public schools, as well as under the bodega, the hangar that houses her researchers. Even Jimenez, the loyal driver and a lover of classical music, attends.

Amid the growing threat of climate change and human interference, Perry says she will continue to study her monkeys and to educate the local community on the importance of ecology as long as she is able.

“I know the day will come when I won’t be able to do this fieldwork, and I do dread that,” she says. “But every new answer inspires more questions, and each additional year of research enables us to address more mysteries. Finally, we’re ready to tackle some of the really big questions that were impossible to ask in the early years. We don’t know what the future holds for these monkeys, but we can be sure it won’t be just more of the same.”

Monkey Tales


Vandal, born in 1989, was the daughter of Abby, the matriarch of Abby’s group. She was an anxious and whiny juvenile but matured into a self-confident adult. Vandal had 11 offspring, eight grandchildren and two great-grandchildren, but half of them died during their first year of life. She and her full sister Diablita (alpha female) were close friends and allies, helping each other fend off attacks by immigrant males. However, when alpha male Tranquilo killed Vandal’s baby and Diablita was still on the run, trying to save her own infant, Vandal changed her strategy: She teamed up with Tranquilo and took the alpha female position from Diablita in 2004. The sisters never fully restored their former intimacy, and Diablita eventually won her position back in 2006. Shortly after Vandal gave birth to her last infant, Peeves, she and Peeves were badly wounded (probably by an eagle), and Vandal disappeared. Her granddaughter Monster adopted little Peeves, caring for him until Vandal reappeared a couple of weeks later, looking gruesome but at least alive! Vandal and Peeves had a close relationship until she finally died at age 25, when Peeves was 3 years old.


Pablo was the alpha male of Rambo’s group for about 17 years. In contrast to the more typically despotic alpha male style, Pablo often groomed the females and his male allies, and he allowed the other males in his group to affiliate and have sexual privileges, both with females and other males. Despite (or perhaps because of) his unusual style of ruling the group, Pablo became the most reproductively successful male in the population, siring at least 25 children, 105 grandchildren, 43 great-grandchildren, and one great-great- grandchild, to date. Pablo’s political expertise permitted him to rule far beyond his physical prime: If he threatened a male intruder from another group, his sons and subordinate allies would rush off to attack the offender, and Pablo did not have to engage in direct physical combat. Pablo was finally deposed by his ally’s son Moth, but he was allowed to stay in the group, caring for his grandchildren until his death.