Scientists: Orangutans Choose Their Food Based On Their Mood
- 23.10.2026, 8:58
The study's findings may also have practical implications for people.
When choosing food, wild orangutans observe other members of their group. They select what they believe has whetted the appetite of other members of their species. As The Guardian, this is the conclusion reached by scientists studying the behavior of great apes.
The researchers found that orangutans who heard recordings of their fellow orangutans laughing before searching for treats rated the food associated with those sounds more highly.
Erika Cartmill, a professor of anthropology and cognitive science at Indiana University and the study’s lead author, explained that this work is part of a larger project. Scientists are seeking to determine whether animals experience joy and how emotions affect their cognitive abilities and learning processes.
“One of our main motivations is to build on human studies that show emotions significantly influence rational thinking. These are not two separate processes—they truly interact with one another. We wanted to test whether this conclusion could be extended to animals, specifically orangutans,” Cartmill explained.
How the Study Was Conducted
In an article published in the journal *Biology Letters*, the researcher and her colleagues described an experiment involving six orangutans from two zoos.
First, the animals were taught to look for treats in bowls. Then each orangutan was presented with two bowls. In one, the treat was hidden under a substance safe for the animals, such as moss or sawdust. The other contained a different material but no food.
Before placing the “dishes” in front of the animals, the researchers played an audio recording. These were either sounds of orangutans playing and laughing or natural sounds, such as the wind. The choice of recording depended on which of the two materials was used to conceal the food that day.
On the fifth day of the experiment, the scientists presented the orangutans with two bowls, each containing treats hidden under one of the two substances, and “asked them to choose.” The results of several test series showed that, overall, the orangutans more often chose the bowl with the substance associated with the sounds of laughter. Four out of six participants demonstrated a clear preference.
According to Cartmill, this behavior can be explained by the fact that the sounds of laughter evoked positive emotions in the orangutans. When the animals associated a particular object with food, this emotional state could influence their subsequent choice.
Interpretation of the Results
Primatologist and evolutionary psychologist Adriano Lameira of the University of Warwick called the results fascinating.
“In fact, upon hearing others clearly having a good time, the orangutans made a request: ‘I’ll have what they’re eating, please!’” the scientist joked.
Cartmill added that the results indicate that when forming associations, it is not only the amount or frequency of reward that matters, but also the animal’s emotional state at the time of learning.
“Our study shows that the animal’s state during the formation of an association also matters. Who you are at a given moment, the circumstances, your emotions, feelings, and thoughts—all of this can influence how you remember the information you’ve learned,” she explained.
According to the researcher, the findings may also have practical implications for humans, particularly in educational settings.
“Students may learn at the same rate regardless of whether they’re in a good mood or not. However, our study suggests that they may value information learned while in a good mood more highly,” Kartmill noted.
This, she said, could help explain why people trust some information more than others, or why students decide to continue studying certain subjects.
For example, if a student feels anxious during math class, this could influence whether they prefer that subject over others when choosing a path for further education.