High in the canopy, a young chimpanzee hangs from a branch, its mother’s hand close by, ready to intervene if something goes wrong. The young ape is still examining the leaves on the branch, but the little one is obviously ready to continue swinging boldly – because at this early age, chimpanzees’ willingness to take risks reaches its statistical peak.
This behavior was investigated by a research team led by Bryce Murray from the University of Michigan. The biologists analyzed video footage of 119 wild chimpanzees from the Ngogo area in Kibale National Park in Uganda. For these great apes, risk is part of everyday life: they often climb and jump through the branches, and a misstep can have serious consequences. It is precisely this way of life that makes chimpanzees’ risk behavior easy to compare and systematically record.
The researchers differentiated between different age groups: chimpanzees are considered infants up to around five years of age, young animals up to around ten years of age and juveniles up to around 15 years of age. The team considered targeted jumps or completely letting go of a branch to be risky behavior – so-called “free flight” movements, in which the animals consciously move through the branches without stopping.
The result was surprising: it was not young animals, but the youngest animals that took the greatest risks. They were around three times more likely to engage in risky behavior than adult chimpanzees. “This is remarkable because this cannot be observed in humans,” says Lauren Sarringhaus, leader of the study.
As chimpanzees grew older, their willingness to take risks continually decreased. Unlike in humans, there were no differences between the sexes. The researchers see a possible explanation in the limited control by the mothers: As soon as the young animals are no longer within arm’s reach, they can hardly restrict their behavior.
However, in humans, babies are under constant adult supervision. Furthermore, risky physical behavior in humans is difficult to study systematically. It would be unethical to specifically give subjects tasks that could cause them to injure themselves. Accordingly, studies on risk behavior are usually based on observations or survey data. The comparison suggests that differences in risk behavior between humans and chimpanzees arise less from biology than from the social environment.