A team of researchers observing and filming orangutans at a research facility in Indonesia has found that they may be smarter than previously thought.
The great apes build large, oval nests in tree canopies where they sleep overnight, possibly for protection from predators and parasites or for warmth during sleep. Little was known about their nests’ mechanical design and material properties, until now.
The research, published in the journal Proceedings of the National Academy of Science, suggests that orangutans, like some birds, might possess engineering expertise.
The findings show that the orangutans use particular branches for different parts of the nest and also break the branches in different ways depending on how they would be used.
“We found that the orangutans chose strong, rigid tree branches for the structural parts of the nests that supported their weight, and weaker, more flexible branches for the nest’s linings, suggesting that the apes’ choice of branch for different parts of the nests was dictated by the branches’ diameter and rigidity,” said Dr. Roland Ennos of the University of Manchester, a lead author on the study.
“Further, branches chosen for the nests’ structural framework were fractured differently from those chosen for the lining: whereas structural branches were broken halfway across, leaving them attached, branches used for lining were completely severed, suggesting that orangutans might use knowledge of the different ways in which branches break to build strong and comfortable nests.”
“We witnessed orangutans building safe comfortable nests by half-breaking and weaving thick branches and twisting smaller branches right off to make a sort mattress,” the researcher added. “They seem to have learnt about the mechanical properties of wood, and use this knowledge in a clever way.”
“Our research has implications for the evolution of intelligence and cognition as well as the evolution of tool use in early humans. It provides evidence that the development of all these traits started in apes because of their need to understand their mechanical environment, not just their social environment.”