Young Orangutans Build Broader Diets by Copying Others — SkimNews
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- Revathe Thillaikumar and colleagues at the Max Planck Institute of Animal Behavior analyzed nearly 7,000 learning instances across more than 1,700 hours of observations of 21 wild Sumatran orangutans at the Suaq Balimbing research station in Indonesia over 12 years.
- Young orangutans who closely observed another orangutan interacting with food continued manipulating new objects or trying new foods for about 145 minutes afterward — behavior Thillaikumar compared to human children imitating an activity they have just seen an adult perform.
- The 21 juveniles varied considerably in learning style — some leaned heavily on social learning, others explored independently far more — patterns Thillaikumar said may reflect personality differences or differences in how mothers care for their young.
- Orangutans that engaged in both substantial social and substantial individual learning acquired the broadest diets, but those with very little truly individual exploration could partially compensate and still develop a reasonably broad diet by being strong social learners.
- Wild orangutans must master a rainforest menu of hundreds of food options — from easy-to-access leaves to the more nutritious seeds at the heart of tough, spiny neesia fruit — before achieving independence at 8.5 years old.
- Elizabeth Lonsdorf at Duke University said the sheer scale of work tracking young orangutans across their full dependency period was impressive, while Michael Tomasello, also at Duke, argued that "predicting dietary breadth at maturity requires looking at all types of learning."
Why it matters: Across 21 juveniles followed for their entire dependency period, the finding dissolves a tidy either/or between social and individual learning: limited solo exploration doesn't consign a young orangutan to a narrow diet if it watches its peers closely. For researchers, the implication stated in the paper itself is that adult foraging competence can only be predicted by tracking both learning modes together, not either one alone.
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