Study: Monkeys are much smarter than we thought they were (2024)

In a groundbreaking study published today in the journal Nature Neuroscience, researchers have discovered that monkeys, much like humans, are capable of complex deliberation and careful decision-making.

This new finding challenges the long-held belief that humans alone possess the ability to think deeply about a problem and consider multiple factors such as costs, consequences, and constraints in order to arrive at optimal outcomes.

“Humans are not the only animals capable of slow and thoughtful deliberation,” said study senior author Dr. William Stauffer from the University of Pittsburgh School of Medicine. “Our work shows that monkeys have a rich mental state that renders them capable of intelligent thinking. It’s a new paradigm for studying the neurophysiological basis for deliberative thought.”

The study raises important questions about the nature of thought processes and decision-making in animals, and whether other species are also capable of engaging in the same level of complexity as humans. It also helps to shed light on the cognitive processes at work when we, as humans, make decisions about various aspects of our lives, such as who to spend time with or what to study in school.

Several decades ago, Dr. Daniel Kahneman, a Nobel Prize laureate, revolutionized the field of behavioral economics with his Prospect Theory. In his seminal book, “Thinking Fast and Slow,” Dr. Kahneman posited that humans employ two distinct systems of thinking: one nearly instantaneous and automatic, and the other much slower and reliant on conscious logical reasoning that requires greater mental effort.

How the study was done with monkeys

Dr. Kahneman referred to the first type of thinking as “slow” and the second as “fast.” Slow, effortful thinking enables us to engage in complex activities such as writing music, developing scientific hypotheses, and balancing our checkbooks. Until now, it was believed that slow thinking was a uniquely human trait.

However, this latest research turns that notion on its head. By presenting monkeys with combinatorial optimization problems, which the researchers dubbed the “knapsack task,” and rewarding the animals based on the value of their solutions, the study demonstrated that monkeys employed sophisticated mathematical reasoning and used efficient computational algorithms to tackle complex problems.

The scientists found that the animals’ performance and speed of deliberation were dependent on the task’s complexity, and that their solutions closely mirrored those generated by efficient computer algorithms specifically designed to solve the optimization problem.

“Results from this work will contribute neurophysiological evidence to enlighten centuries of discussions about dual process theories of the mind, the structure of thoughts, and the neurobiological basis of intuition and reasoning,” wrote Stauffer in an accompanying research briefing.

Tao Hong of Carnegie Mellon University is the lead author of the paper. The study’s findings not only provide valuable insights into the cognitive abilities of monkeys but also pave the way for a new paradigm in studying the neurophysiological basis for deliberative thought, with potential implications for better understanding the complex nature of decision-making across various species.

More about monkeys

Monkeys are a diverse group of primates that belong to the infraorder Simiiformes. They are divided into two major groups: New World monkeys, native to Central and South America, and Old World monkeys, native to Africa and Asia. Monkeys are known for their intelligence, social behavior, and adaptability to different environments.

Physical characteristics of monkeys

Monkeys vary greatly in size and appearance, ranging from the tiny pygmy marmoset, which measures just 4.6-6.2 inches (12-16 cm) in length, to the large mandrill, which can reach up to 37 inches (94 cm) in length.

Monkeys typically have forward-facing eyes, flat faces, and dexterous hands with opposable thumbs. Some species also have prehensile tails, which they use to grasp and manipulate objects or to hang from branches.

Diet of monkeys

Most monkeys are omnivores, eating a diverse diet that includes fruits, leaves, seeds, insects, and small animals. Some species, like the howler monkey, primarily consume leaves, while others, like the capuchin monkey, have a more varied diet.

Social behavior of monkeys

Monkeys are highly social animals that usually live in groups called troops. These troops can range in size from just a few individuals to hundreds of members. Social hierarchies are common in monkey troops, with dominant individuals enjoying benefits like better access to food and mating opportunities. Monkeys communicate through vocalizations, body language, and facial expressions, and they often engage in grooming behaviors to maintain social bonds.

Intelligence and tool use

Monkeys are known for their cognitive abilities, problem-solving skills, and in some cases, their use of tools. Capuchin monkeys, for example, have been observed using rocks to crack open nuts, while some macaques have been seen using sticks to extract insects from tree bark.

Research has also shown that monkeys are capable of understanding basic arithmetic and recognizing themselves in mirrors, which is considered a sign of self-awareness.

Conservation of monkeys

Many monkey species are threatened by habitat loss, hunting, and the illegal pet trade. Conservation efforts are underway to protect these primates and their habitats, including the establishment of protected areas, reintroduction programs, and education campaigns to raise awareness about the importance of monkey conservation.

In conclusion, monkeys are fascinating and intelligent creatures with complex social structures and diverse behaviors. As we continue to study these primates, we gain a greater understanding of their cognitive abilities and the evolutionary links between humans and other primates.

Other animals that demonstrate problem-solving ability

Yes, numerous animals demonstrate problem-solving abilities, indicating the presence of intelligence and cognitive skills across various species. Some examples of animals with notable problem-solving capabilities include:

Crows and other corvids

These birds are known for their exceptional problem-solving skills and have been observed using tools to access food. For instance, they can use sticks to extract insects from tree bark or crevices and even bend wires to create hooks for retrieving food from hard-to-reach places.


Elephants are highly intelligent animals capable of complex problem-solving. They have been observed using sticks and branches to swat flies or scratch hard-to-reach areas and can also recognize themselves in mirrors, suggesting self-awareness. Elephants have displayed the ability to cooperate and work together to solve problems, such as pulling a rope simultaneously to access food.


Dolphins are known for their intelligence and problem-solving abilities. They have been observed using tools like sponges to protect their snouts while foraging on the ocean floor. Dolphins can also learn and understand complex commands and have been shown to recognize themselves in mirrors, indicating self-awareness.


These highly intelligent invertebrates have demonstrated remarkable problem-solving skills. Octopuses have been observed opening jars, navigating mazes, and escaping from enclosures by manipulating objects and their environment. Their impressive learning and memory capabilities make them formidable problem solvers.


Domesticated dogs have evolved alongside humans and have developed a range of problem-solving skills. They can learn commands, understand gestures, and follow human cues to solve problems, such as locating hidden objects or navigating obstacles. Some breeds, like border collies and poodles, are especially known for their intelligence and problem-solving abilities.


As our closest living relatives, chimpanzees share many cognitive traits with humans. They have been observed using tools, such as sticks to extract termites from their mounds, and leaves as sponges to collect water. Chimpanzees also display complex social behaviors, such as cooperation and deception, which require problem-solving skills.


Rats are intelligent rodents that have shown the ability to solve problems and learn from their experiences. They can navigate complex mazes, recognize patterns, and demonstrate a rudimentary understanding of cause and effect. Rats have also been observed using tools and adapting their behavior based on previous experiences.

These examples illustrate that problem-solving abilities are not exclusive to humans and can be found across various animal species. Studying these animals and their cognitive skills can provide valuable insights into the evolution of intelligence and the diversity of problem-solving strategies in the animal kingdom.


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Study: Monkeys are much smarter than we thought they were (2024)


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