Young Orangutans Build Diets by Watching Peers — SkimNews
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- Revathe Thillaikumar at the Max Planck Institute of Animal Behavior led a study analyzing nearly 7,000 learning instances from more than 1,700 hours of observations of 21 young Sumatran orangutans at Indonesia's Suaq Balimbing research station across 12 years.
- Young orangutans must master which foods are safe and how to process them before reaching independence at 8.5 years old, drawing on both social observation and solo exploration in varying proportions that may reflect personality or differences in maternal care.
- Good social learners who engaged in very little independent exploration still developed reasonably broad diets — though individuals combining high levels of both individual and social learning achieved the broadest range of foods overall.
- After closely watching another orangutan interact with a food item, young apes continued practicing the behavior for about 145 minutes, a pattern Thillaikumar compared to how human children imitate adults they've just observed.
- Elizabeth Lonsdorf and Michael Tomasello at Duke University praised the study's unprecedented scale and stressed that predicting dietary breadth at maturity requires accounting for all forms of learning together, not any single one.
- The findings were published in Science (DOI: 10.1126/science.adz6415), drawn in part from roughly 4,700 hours of feeding observations on 13 of the youngsters.
Why it matters: The work, one of the longest individual-level learning studies of any wild ape, shows that dietary breadth depends on the interplay of social and individual learning rather than either alone — a nuance that complicates assumptions used in orangutan rehabilitation, where orphaned apes must often acquire survival skills before release into forests offering hundreds of food types.
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