Brave, cautious and quick-witted: monkeys have ‘personalities’ too

Some monkeys are better at following human cues. Others are more confident at solving problems without social cues. Some figure out where to look for food more quickly, whilst others act differently. Scientists therefore suggest viewing apes not only as members of a species, but also as individual animals with their own experiences, strengths and weaknesses.

The researchers did not apply everyday labels such as ‘brave’, ‘lazy’ or ‘stubborn’ to the monkeys. Instead, they studied consistent differences in how the animals solve cognitive tasks.

The study has been published in *Psychological Science*.

Details

The study involved 48 great apes of four species: bonobos, chimpanzees, gorillas and orangutans. The scientists observed them not just for a single day, but for around a year and a half. During this time, the animals undertook six different cognitive tasks.

The tasks tested various abilities. For example, whether a great ape could track a human’s attention, understand communicative cues, remember where it had already searched for food, or reason in more ‘non-social’ situations.

The results proved significant: the differences between individual apes were noticeable and relatively consistent. In other words, an ape that performed better on a particular task often maintained this ability across more than one test.

The results were influenced not only by species but also by individual factors: the group in which the animal lived, previous experience of participating in research, sex and rearing conditions.

What does ‘character’ mean in monkeys?

In everyday language, we might say: one monkey is bolder, another more cautious, and a third quicker on the uptake. This works well for a headline: it makes it easier for the reader to grasp the idea.

But the scientific conclusion is more precise. The point is that great apes exhibit individual differences in thinking and behaviour. They are not identical ‘copies’ of their own species.

It’s similar to humans. In a single class or family, children may solve problems in different ways: one is better at spotting clues, another is better at remembering details, and a third is quicker to try out new approaches. According to the study, monkeys also exhibit such consistent differences.

What surprised the scientists

The researchers expected that different tasks would be grouped in much the same way as is often described in humans: social thinking in one category, reasoning in another, and self-control in yet another.

But with great apes, the picture turned out to be more complex. Tasks involving social cues did not always correlate with one another. If an animal performed well on one social task, this did not necessarily mean it would perform just as well on another.

On the other hand, many non-social tasks – such as those involving reasoning – were more frequently linked to one another. This suggests that the thinking of great apes may not be organised quite in the way we are used to describing human intelligence.

Why this is important

Such research helps us understand how intelligence developed in humans and our closest evolutionary relatives.

Previously, scientists often framed the question as: ‘Can this species do such-and-such?’ For example, can chimpanzees follow a gesture, do gorillas understand a cue, or do orangutans remember where food is?

This new study shows that this is not enough. We also need to ask: why does one ape perform better than another, even if they belong to the same species?

If we fail to take individual differences into account, we risk drawing conclusions that are too sweeping. For example, we might conclude that the entire species ‘cannot’ perform a task, even though some animals can and others cannot, due to experience, age, rearing conditions or other factors.

Background

Great apes include chimpanzees, bonobos, gorillas and orangutans. They are the animals most closely related to humans amongst modern species, which is why they are often studied to understand the origins of human thought.

However, it is difficult to compare humans and apes directly. Humans have language, schooling, culture, education, technology and a wealth of social experience. Apes have a different way of life and different ways of interacting with the world.

This is precisely why scientists are cautious: the research does not claim that apes think like humans. It suggests that their thinking cannot be reduced to a simple model either. They have individual characteristics, and it is important to take these into account.

Limitations

The sample size was small — 48 animals. This is typical for research involving great apes: there are few such animals, and working with them is complex and time-consuming.

However, because of this, we cannot draw overly broad conclusions about all monkeys in the world. Further research is needed, preferably involving long-term observations, to understand how such differences develop and change over the course of a lifetime.

Source

Study: Manuel Bohn et al., “Individual Differences in Great Ape Cognition Across Time and Domains: Stability, Structure, and Predictability”, Psychological Science, 2026.