Young orangutans learn mostly by watching their mothers, study finds

Humans learn a great deal by watching others — and until the mid-20th century, scientists considered this kind of observational learning a uniquely human trait. Subsequent research, however, found the ability in vertebrates broadly, and even in insects.

Now a new study shows that wild infant orangutans observed others five times more often than they explored on their own, and that the young apes who did the most of both — watching and independent exploration — knew how to eat the greatest variety of foods by the time they left their mothers.

The findings were published in volume 393, issue 6818 of the international journal Science by T. Revathe and Caroline Schuppli of the Max Planck Institute of Animal Behavior in Germany, who analyzed how wild Sumatran orangutan infants acquired foraging skills over eight years.

Young Sumatran orangutans stay close to their mothers for about eight years before becoming independent. Adult orangutans eat around 250 foods out of thousands of candidates in the forest, many of which require preparation before eating and some of which require tools. Infants must therefore learn what to eat, how to prepare it, and where and when to find it — all before striking out on their own.

The research team followed 21 infant orangutans for more than 1,700 hours over 12 years at a study site on the Indonesian island of Sumatra. The researchers classified close, sustained observation of another orangutan as social learning; manipulating, breaking apart, or attempting to eat objects was classified as individual exploration.

On average, infant orangutans watched other orangutans 1.25 times per hour and engaged in exploratory behavior 3.71 times per hour. The raw numbers make independent exploration appear far more common, but the infants' exploratory activity increased sharply right after they watched another orangutan — and it took 145 minutes, or about two hours and 25 minutes, for that elevated exploration to return to baseline.

Using that 145-minute window as a threshold, the team classified any exploration that occurred within 145 minutes of an observation episode as socially triggered, and any exploration that began after that window as truly independent.

Of 4,649 recorded exploration instances, 4,235 — or 91 percent — followed an observation episode and were classified as socially triggered. Truly independent exploration was limited to 414 instances, occurring roughly 0.25 times per hour, one-fifth the rate of social observation at 1.25 times per hour.

In other words, although infant orangutans appeared on the surface to be constantly experimenting on their own, the vast majority of that behavior was in practice triggered by watching another orangutan first.

The team also recorded 303 foods eaten by 13 infant orangutans before they became independent, then estimated how the balance of social and individual learning for each infant related to the number of foods it could eat by the time it left its mother.

Infants that did more of both — social observation and independent exploration — above the average turned out to know how to eat the greatest variety of foods.

However, the team said the conventional framework that divides animal learning neatly into social and individual categories struggles to capture how wild animals actually learn. Because most of the infants' exploration followed observation episodes, the two modes were deeply intertwined rather than separate.

The researchers said the results suggest that great apes learn in a way that closely resembles the complex, cumulative process by which humans build knowledge through observation.

The team also noted that individual mothers differ in how they interact with their young, meaning maternal influence could be substantial. They added that future research should examine whether differences in learning style among infants stem from environment, developmental history, or genetics.

DOI: 10.1126/science.adz6415

T. Revathe, M.-T. Weidling, S.S. Utami-Atmoko, T. Mitra Setia, I. Razik, C.P. van Schaik, A. Whiten, P.-C. Bürkner, & C. Schuppli, How 8 years of social and individual learning interact to shape ecological competence in orangutans, Science 393 (2026) 1369-1374.