Horizontal rays of light pierced the canopy, giving the tops of leaves a ruddy shine. I was alone in the forest, and I wanted to return home before dark. But I also wanted to see where Mitchell, an enigmatic adolescent chimpanzee, made his nest for the night. I live in the middle of the Ugandan forest, at Ngogo Research Camp, which is within the territory of the Ngogo chimpanzee community. I’m here to study the transition to adulthood in male chimpanzees. Teenage males, who have spent their entire lives traveling alongside their mother, must forge independent relationships with group mates. How do they fare as they attempt to make friends, mate, and climb the dominance hierarchy? Also, what are the traits that define adulthood?



Time-worn Chi-chi, Aaron's stuffed animal

Studying chimpanzees is a defining trait of my own adulthood. When I was five years old, I picked out a stuffed animal gorilla at a children’s clothing store. I named him Chi-chi (pronounced “chee-chee”) and promptly decided to study apes in the wild when I grew up. I spent years toting Chi-chi around, and he and sixty other stuffed animal primates slept on my bed (until I left for college, when my parents moved them to the attic). The summer after I hit puberty, I came face to face with an adolescent gorilla at the Franklin Park Zoo in Boston, the beginning of the inextricable connection between my coming of age and apes. The lanky, ten-year-old gorilla had tried to find freedom outside the zoo, whereas the zoo is where I found mine. I spent every free moment of high school volunteering at the zoo, sometimes skipping class to hose away feces, observe the gorillas, and cuddle cockatoos.


My work with captive animals strengthened my desire to study apes in the wild. I applied to Duke because of the plethora of primate classes and opportunities for research at the Duke Lemur Center. It lived up to my expectations, as I became immersed in primate evolution, lemur cognition, and ape social behavior. After my junior year, my dream of studying apes in the wild came true. I spent a summer in Uganda’s Kibale National Park, observing play behavior in infants of the Kanyawara chimpanzee community. I had made it to Africa. My childhood dream was becoming ever more tangible, as the precipice of adulthood was becoming ever more imminent.

Sandel worked at the Lemur Center while at Duke. Photo by Ricki Oldenkamp

Now, here I am, trying to determine metrics of adulthood for wild chimpanzees. Mitchell, the elusive adolescent whom I followed until sunset, is approaching that phase, but he has work to do. He rarely spends time with other chimps (which is why I have so little data on him). The exception is Mulligan, a silver-haired adult male. They make an odd couple. Large males usually spend their time combing through the fur of other adults and engaging in the never-ending fight for high status. Mulligan does do some strutting around, but it seems that his affinity for Mitchell takes priority. As dusk began to fall, Mulligan appeared ahead on the trail. He soon climbed into a tree and began bending and cracking branches to make a nest. Mitchell followed suit, finding a small tree twenty feet away to make his bed for the night.

Friendship, which is a term increasingly used to describe the social relationships of primates and other mammals, is exemplified by adult male chimpanzees. Among adults, males have favorite chimpanzees whom they groom and travel with. These preferences are noticeable as chimpanzees live in “fission-fusion” communities, in which subgroups, or cliques, form throughout the day. At any point, one chimpanzee may split off to find others or to be alone.

The dynamic nature of chimpanzee life makes collecting data difficult. I follow young males for one hour at a time, recording their every social interaction, and fission and fuse along with them. After one hour, I hope that whoever I’m following has found another subject for me to observe. My goal is to get one thousand hours of observation spread evenly across eighteen young males. But chimps don’t spend equal time with one another, and I am often left with fewer hours on the loners.

That is why, on a dry morning in January, I was excited to see the chimpanzee for whom I have the least data. Hawkins is a twenty-yearold momma’s boy who prefers that humans don’t follow him. That day, I was determined to stick to him.

I started the morning pacing underneath a fig tree, trying to recognize faces amidst the leaves. Studying nearly 200 chimpanzees requires recognizing each individual, which is no easy task. To aid in memorization, researchers name each chimp. David Watts and John Mitani, who began research on the Ngogo chimpanzees twenty years ago, named many chimpanzees after jazz musicians—Miles, Monk, Ellington, etc. Others are named after opera singers, contemporary actors, peace activists, and a few after pioneers in primatology, such as Struhsaker, who is named after Tom Struhsaker, a scientist at Duke who began research in Kibale Forest in 1970 and established Ngogo Research Camp. Today, whoever is first to see a new infant or immigrant gets naming rights.

Looking up into the fig tree, I could make out the silky hair andprotruding brow of Hicks, another young adult male. I also saw the sloping face and swollen eyes of Haden, a rotund not-quite adult. Then there were whoops, wheezes, and screams to the east: the “pant hoot” calls chimpanzees use to communicate across far distances. Immediately three of the chimps in the tree, including Hicks, slid down trunks like firefighters and headed toward the calls. I followed them, along with Ambrose Twineomujuni, one of the Ugandan chimp trackers who helps collect long-term data on the Ngogo community. Soon we caught up to a group of males, including Hawkins and Mitchell.

When Hawkins took off at a trot, I followed. Ambrose stayed behind with the newly formed subgroup. My thighs burned as I tried to keep my eye on the black mass of his body ahead, but soon he was lost in the thick vegetation. I strained my ears for the sound of dead leaves crunching beneath his feet. Silence. I had lost the chimp.


Collecting chimpanzee urine. Photo by Tom

It used to be boring watching chimpanzees. So boring, in fact, that it led to an existential crisis in July of 2013. I originally intended to study social relationships in infant chimpanzees, but I was still learning to recognize and follow adults, let alone the nameless, tan-faced, subadults. I didn’t have a clear project, so it felt like I was just wandering the forest, gazing at chimps. I would count the hours until I could return to camp, crouch under the bag of water heated tepid by the sun, put on clean clothes, eat dinner, and read in my tent.


I escaped to books. Reading Crime and Punishment, I began to identify with Raskolnikov, the deranged, youngadult protagonist. I wandered through the verdure of the forest and felt nothing while Raskolnikov wandered the city streets of Russia feeling the same. Like him, I was without direction. Who was I if not a primatologist? What of my childhood dreams? Dostoevsky’s prose felt familiar: “[…] as though he actually imagined he could think the same thoughts, be interested in the same theories and pictures that had interested him…so short a time ago. He felt it almost amusing, and yet it wrung his heart.”

I considered quitting. I brought up my angst about primatology with my adviser, John Mitani. “What about all your stuffed animal primates?” he barked. He was right. I hadn’t blown out two decades’ worth of birthday candles wishing to study apes in the wild for nothing. I decided to study friendship in young males as they become adults. Being twenty-six, I could transition to adulthood alongside them.

Here I am, still in the jungle. My childhood dream has survived, as has Chi-chi, save for a violent encounter with my dog in the 2000s in which he lost his nose. In fact, I’ve brought him along with me to Uganda as an additional prophylaxis against existential crises. There are still occasional moments of boredom. After all, chimpanzees spend much of their time in trees feeding or resting, barely in view. While their lives are filled with melodrama— grooming, screaming, slapping, hugging—it’s not every day that something truly dramatic occurs, like a monkey hunt or patrol of the boundaries. But my apathy has been replaced with anxiety. Each successful hour of observation is a source of joy. Each time I lose the chimp is a source of sadness. Which brings me back to losing Hawkins one morning in January.

If I hadn’t followed Hawkins, I would have had a very different day. The group Ambrose was following continued north and didn’t stop. They decided to be dramatic. They went to the northeast edge of their territory, and began quietly walking single- file in search of their neighbors. Chimpanzees are highly territorial and will make military-like incursions into the homeland of nearby chimpanzee communities. If they find and outnumber the neighbors, they will kill any adult males they can catch, and they will rip any infants they find out of the mother’s arms.

On that day, they surprised a small group of chimpanzees and caught an adult male. Ambrose watched as the Ngogo males bit his arms, legs, and face, ripping his lower lip in two, and pounding at his chest. This lasted for thirty minutes, until they left him for dead. Three young adults, including Hicks, were part of the patrol, but they stayed to the side as five older males conducted the attack. Apparently Hicks was not adult enough.

The next day we went in search of the corpse. Although an important part of chimpanzee behavior, lethal aggression is rare to observe. It is also rare to find the dead body of a wild chimpanzee. We wanted to assess its injuries, measure its body size, collect skin and hair samples, and move the chimpanzee into a location where we could let it decompose and later collect the bones.

We found the body of the chimp at the edge of a brook, where he had died still holding a branch. I donned three pairs of exam gloves, a facemask, and a cheap pair of pajamas over my clothes as scrubs. (HIV came from a chimpanzee version of the virus, likely jumping to humans when people butchered chimpanzees for food, so disease risk is very high.) The Ugandan staff who usually maintain the forest trails made a “stretcher,” and after covering the body in plastic bags, they tied it up and carried it closer to camp.

Lying in bed that night, I couldn’t get the image of the corpse out of my head. I ran my hand against my chest and stomach, the feel of my skin and hair not unlike that of the chimp. The similarities between chimpanzees and humans are striking, from the way they sit with their legs crossed, their heel resting on their knee, to the way they hum to themselves when eating certain foods. It is no surprise they are our closest living relatives.

Dissecting a wild chimpanzee was too much of a reminder of this. And it was not part of my childhood dream. Maybe, like Hawkins, who avoided going on patrol, or Hicks, who was not allowed to take part in the fight, I’m not adult enough. After that gory endeavor, I was particularly grateful to sit among living chimpanzees, observe their friendlier side, and remain on the cusp of adulthood a little bit longer. 

Since June 2014, Sandel ’10 has been studying adolescent chimpanzee behavior in Uganda’s Kibale National Park. The trip is part of his Ph.D. in biological anthropology at the University of Michigan. He studied evolutionary anthropology at Duke.

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