Shrink, a spotted hyena in Tanzania, was born at the lowest social status in his clan. His odds of survival were stacked against him.
However, to the surprise of a team of researchers observing his behavior, Shrink’s social prowess during his teenage years earned him a higher status in adulthood, granting him the ability to join new clans and become a popular mate.
“It’s a hyena rags to riches story,” said Barbara Natterson-Horowitz, a UCLA cardiologist. “I think a lot about the role of the lack of advantage for young people, and how it shapes their destiny.”
Natterson-Horowitz and science journalist Kathryn Bowers detailed the life of Shrink and other animals in their book Wildhood, published last month. The book explores the key lessons and traits of adolescence commonly found in many different species, including humans.
During adolescence, physically developed young animals undergo crucial experiences, learn from mentors and test themselves against others on their way to becoming a mature adult, according to the book.
Natterson-Horowitz, who also co-directs UCLA’s Evolutionary Medicine Program, and Bowers developed a specific research methodology to uncover connections and commonalities among animal species across the kingdom.
“We started to find in our research that very often there are a lot of unexamined assumptions about human exceptionalism and uniqueness,” Natterson-Horowitz said. “We began seeing the process of becoming a mature adult as something common to every animal.”
The book covers the adolescent struggles of many different species, but focuses on four primary lessons crucial to surviving the coming-of-age across species: avoiding danger, navigating social hierarchies, communicating sexually and caring for oneself after leaving home.
One focus of the authors’ research was mortality and danger, Natterson-Horowitz said. For example, adolescence for humans is a dangerous time because they tend to take more risks. This behavior leads to higher rates of crime, accidents, mental illness and addictions, according to the book.
In young and inexperienced birds, fish and mammals, there was a similar spike in mortality, Natterson-Horowitz said. Adolescents faced predators specifically targeting them, exploitation from older animals, and unfamiliar landscapes, among other dangers.
The authors’ interest in adolescents first came from bold adolescent sea otters swimming in shark-infested waters that most other adults avoided. Young otters who were able to survive these dangerous waters became more experienced in detecting and avoiding predators in the long run, Natterson-Horowitz said.
“For young humans, it’s also a good time to explore and take risks, … learn your limits,” said Daniel Blumstein, a UCLA ecology and evolutionary biology professor who works with Natterson-Horowitz.
Life experiences are important in shaping how animals weigh risks and make decisions, Blumstein said. For example, in his research with marmots, he found pups would run away from researchers if they approached them at a similar distance. However, as they grew older, that distance would differ widely between different marmots and their experiences.
“Everyone’s equally bold as pups,” Blumstein said. “Then they’re nervous Nellies and coolheaded Lucys later in life.”
However, risk-taking behaviors may actually serve an adaptive purpose, such as predator inspection, Natterson-Horowitz said. For example, scientists observed adolescent velvety free-tailed bats flew directly toward another bat’s distress calls in order to observe and gather information about their predator.
Maturation is an often overlooked topic in biology research, especially among nonmammalian species such as insects and amphibians, said Gregory Grether, an ecology and evolutionary biology professor.
Understanding the development of anti-predator behavior during adolescence is important for programs reintroducing endangered species from breeding captivity back into the wild, he added.
“One of the reasons they fail frequently is because (captive adolescents) don’t know how to make a living, find shelter (or) avoid predators,” Grether said.
For example, the book touched on how young salmon farmed in captivity and released into the wild had a disproportionately higher mortality rate than wild salmon, because they had no experience with their natural predators.
Another part of the book, which deals with navigating social hierarchies, was born from the authors’ interest in how social media is linked with anxiety and depression in adolescents, Natterson-Horowitz said. The authors identified human neurobiological systems involved in the act of comparing oneself to others – common in social media – and found similar systems in crustaceans, fish, birds, mammals and reptiles.
“We were able to look at why status is so important in animals, and began to connect it with the human experience. … We call it a 600 million year history of social media obsession,” she said.
As a result, animals such as hyenas, chickens, fish and lobsters all organize themselves in social hierarchies, in which those who are at the top assert their dominance and have access to more resources.
Both authors had adolescents of their own to raise while writing the book. Natterson-Horowitz said this helped them understand how sensitive adolescents can be to how peers perceive them, as well as the pain of falling in status, the complexity of relationships and the powerful effects of social media.
“If we tried to write a book about adolescents without raising our own kids, it would not have been the same book,” she said.
Natterson-Horowitz said she also was inspired to touch on a variety of issues she often heard from her students during office hours, as well as when she trained as a psychiatrist at UCLA.
“One of the things I really felt was important was to use this framework (in the book’s research) to improve the quality of campus wide conversation about tough issues … like privilege and sexual consent,” she said.
A surprising revelation in the authors’ research was that many animals did not start reproducing right after they became sexually developed, Natterson-Horowitz said. In fact, some species spent years during adolescence learning how to perform courtship rituals before finding a mate.
For example, young male humpback whales must first practice their singing skills to compete with the older and more experienced singers in order to attract a female. Similarly, many students are also sexual beginners in college with a lot to learn about courtship and themselves, Natterson-Horowitz said.
By understanding the complexity of courtship rituals, the authors likened the rituals to proper sexual consent between two humans, she added.
“What we call courtship in animals is essentially is a long back and forth, multistep conversation between two animals, deciding yes or no,” she said. “Even looking at fruit flies, their little insect brains are signaling interest or no interest.”
She added she hopes to teach a course about understanding human adolescence through an evolutionary biology perspective under UCLA’s Evolutionary Medicine Program sometime soon.
“When you are coming of age in college, you’re not really in the adult world, but definitely (aren’t) a child anymore. It’s a very hard period of life, but it’s very hard in nature as well,” she said. “This period is for failing, trying again and getting a little better. It’s tough for adolescents on planet Earth.”