Chimpanzee Study Suggests Supervision, Not Danger Seeking, Influences Adolescent Risk-Taking

Adolescents in the U.S. exhibit a higher incidence of injury-related mortality compared to younger children. A recent study involving chimpanzees proposes that this increase in risk-taking during human adolescence may not stem from an elevated desire for danger, but rather from reduced supervision, which creates more opportunities for risky behaviors.

Methodology

Researchers investigated locomotion patterns in chimpanzees, a species closely related to humans, as a model for physical risk-taking. Studying physical risk-taking in humans directly is ethically complex due to safety concerns. Wild chimpanzees, which frequently navigate arboreal environments at significant heights, offered an alternative subject.

Observations conducted by Bryce Murray, an undergraduate student, identified variations in the danger levels of chimpanzee movements in trees. While chimpanzees typically climb or swing with secure grips on branches, they also perform leaps across gaps and drops from one branch or to the ground. Falls have been documented as a significant cause of injury and mortality among wild chimpanzees.

The study aimed to determine if chimpanzee physical risk-taking, such as leaping and dropping, followed patterns observed in humans, specifically in relation to puberty. An additional inquiry concerned potential sex differences in risk-taking, given some evidence of higher risk-taking in human males, which varies culturally.

Findings

The research involved over 100 wild chimpanzees from Ngogo, Kibale National Park, Uganda, ranging from 2 to 65 years old. The findings indicated:

• Age-Related Risk-Taking: Chimpanzees exhibited the highest rates of daring locomotion during later infancy (ages 2-5). Rates of leaping and dropping progressively decreased with age.
• Comparison to Adults: Older infants were three times more likely to perform risky behaviors compared to adults (over 15 years). Juveniles (ages 5-10) were 2.5 times more likely, and adolescents (ages 10-15) were twice as likely. Infants under age 2, who spend most of their time clinging to mothers, were not included.
• Adolescence: Adolescence in chimpanzees did not represent a peak in risk-taking; instead, it was a point within a gradual age-related decline.
• Sex Differences: No significant sex differences in risk-taking were observed at any age, consistent with previous research on chimpanzee movement patterns.

These findings align with prior laboratory studies on gambling risks in chimpanzees, where individuals demonstrated increased risk aversion with age. Both physical and gambling contexts indicated no peak in risk-taking at puberty for chimpanzees.

Implications for Human Risk-Taking

Chimpanzee mothers are generally unable to restrict their offspring's behavior effectively beyond the age of 2, at which point infants reduce clinging and consistent contact. In the observed leaping and dropping incidents, 82% of infants were beyond arm's reach of their mothers.

In human societies, parental and alloparental supervision of children is common across cultures, with restrictions often loosening during adolescence. The study hypothesizes that if human children experienced less close supervision, younger individuals might engage in more physical risks prior to adolescence. This chimpanzee research contributes to understanding how supervision may influence physical risk-taking in humans.

Unanswered Questions

Other factors may contribute to the observed decline in physical risk-taking among maturing chimpanzees. For instance, increased caution in adults might be necessary, as older primates, despite fewer falls, may sustain more severe or fatal injuries due to greater weight and reduced bone flexibility.

Studying chimpanzees offers insights into the evolutionary and cultural components of human development. While concerns about childhood injuries are valid, minor injuries may be a normal aspect of development. Play during childhood, when bones are more resilient, could provide opportunities for practicing risky behaviors more safely. Some anthropologists propose that increasing children's access to thrill-seeking play may support the development of motor skills and skeletal strength.