Our upright gait is one of the defining features of our humanity. But on occasion, non-human primates also walk upright, often when carrying food.
A new study shows that bearded capuchin monkeys walk on two legs more often than once believed. They even walk upright as they climb trees and scale cliff faces, as the video above reveals.
The monkeys walk "bipedally" on a daily basis, the researchers write. They do so on woody vegetation angled at slopes ranging from 0 to 90 degrees: in other words, from entirely horizontal to vertical.
"The vertical bipedalism is the interesting case that has apparently been missing in the scientific literature," says team member Tiago Falótico of the University of São Paulo in Brazil.
"When climbing with two legs, the monkeys use almost exclusively their hind limbs for propulsion and support, much like human bipedalism," he says. "This behavior could be used as [a] model to better understand the evolution of bipedalism in our own lineage."
The findings have been published in the journal Primates.
Footage provided exclusively to BBC Earth with thanks to Tiago Falótico.
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