Rejection and loneliness are a part of life for these adolescent chimpanzees
When chimpanzees reach adolescence, life becomes very different from what they've experienced so far — they must find their place in the complex social world of adults.
Rachna Reddy, a biological anthropologist and primatologist at the University of Utah, studies the lives of adolescent chimpanzees in Uganda.
"On a very good day, I'll spend 12 to 13 hours with them and watch everything they do — go with them everywhere that they go," she said in Teenager, a documentary from The Nature of Things.
Before reaching puberty, chimpanzees usually move through the world with a caregiver. During adolescence, they become more independent: their relationships with their caregivers change, and they explore different types of relationships with other individuals.
Male chimps stay in the same community, so their relationships change with the individuals they've known their entire life.
Females typically migrate to a new social group. It's an extreme change, but it's essential to avoid inbreeding.
"The other group, they're strangers," Reddy said. "[The adolescent females have] grown up fearing being killed by them or wanting to kill them."
In the video below, Reddy explains how Fricka, an adolescent chimpanzee, fares as she leaves her home and tries to integrate in a hostile new environment.
For male chimpanzees, adolescence marks a dramatic shift in how other adult males treat them.
"[Adult males] tend to, in general, be pretty nice to infants and juveniles — outside of a short period where they try to kill them — shortly after their birth," Reddy said. "They'll tickle infants. They'll throw them up and down, airplane them. They'll embrace them. They'll groom them."
When chimps reach adolescence, adult males will stop grooming them. About a year later, the adults become aggressive. And even as the younger ones navigate these changes, they often participate in extremely dangerous boundary patrols to protect and expand their territory.
"You have to join," Reddy said "If they don't go, they may not integrate into that world. So it's a really critical behaviour."
Patrols and migrating to a new group are difficult rites of passage, which define the adolescent experience for chimps. And on top of that, they face rejection and loneliness.
"Once they're adolescent, they start being ignored," Reddy said. "They're not cute anymore. Adults are not grooming them, not wanting to tickle them as much, not giving them the special type of affection and tolerance that they give to juveniles.…
"If you're with a group of chimpanzees and there's kids playing and adults grooming each other and some individual sitting off to the side, hunched over, alone — that individual is often an adolescent chimpanzee."
As chimpanzees grow up, as in other species, they must separate from their families and find their own way. Every animal, including humans, must go through the process of becoming an adult.
Teenager explores the science of adolescence and helps us understand this dramatic, mysterious and critically important phase of life.
Watch the documentary now on CBC Gem and The Nature of Things YouTube channel.
