In all animals, number sense is closely linked to intelligence and survival. Gray wolves require specific numbers in their packs to hunt, depending on their prey. If it’s elk, six to eight wolves are needed to be successful; for bison, nine to 13 are necessary.
Despite a common belief, counting is not unique to humans. In fact, a vast range of animals understand numbers, helping them to solve a variety of problems, such as acquiring food, defending themselves, navigating and even finding a mate. For example, honeybees remember the number of landmarks they pass as they travel between food sources and their hives. Desert ants count steps to track how far they have traveled from their nests on foraging trips. Counting the pulses in the croaks of male tungara frogs helps female tungara frogs find mates. Gray wolves require specific numbers in their packs to hunt, depending on what they are pursuing. When it’s elk they’re after, six to eight wolves are needed to be successful; for bison, nine to 13 are necessary. Their prey use numbers, as well; elk will split into smaller herds to avoid encountering wolves or combine into larger herds to limit their chances of being hunted.
Now, researchers have made a groundbreaking discovery regarding number sense in animals by confirming the existence of it in rats, offering a crucial animal model for investigating the neural basis of numerical ability and disability in humans. And, according to scientists, male mosquitofish—a matchstick-sized fish endemic to Central America and now found globally—possess impressive problem-solving skills and can successfully navigate mazes and other tests.
Being able to count even helps spotted hyenas decide whether to fight or flee. When animals fight, the larger group tends to win. So, hyenas listen to the sound of intruders’ voices to determine who has the advantage.
Honeybees memorize the visual characteristics of landmarks—such as rocks, trees or other prominent features—around their hives and along their foraging routes. To get back to their homes, they use these memorized landmarks as guides and even count them, which helps them to navigate more accurately.
Rats demonstrate specific brain areas for dealing with numbers
Number sense aids an animal’s perception of the world and increases the chance of survival. It is also an important cognitive ability, fundamental to mathematical aptitude, a hallmark of human intelligence. About 3% to 7% of people suffer from dyscalculia, a learning disability that affects the capacity for learning arithmetic and mathematics; a deficit in number sense is one of the major symptoms.
Number sense refers to the capability to compare, estimate and manipulate nonsymbolic numerical quantities, rather than associated magnitudes, which are continuous dimensions inherent in a group of items, such as the area of visual objects or the duration of sound pulses. There have been challenges regarding whether number sense can be assessed in isolation from the influence of continuous magnitudes. Also, there has been a vivid ongoing debate regarding whether the sense of magnitude or number sense is more fundamental.
Recently, a research team from City University of Hong Kong and the Chinese University of Hong Kong Faculty of Medicine developed an innovative approach that employs a novel numerical-learning task, brain-manipulation techniques and artificial-intelligence modeling to resolve an ongoing argument about whether rats have a sense of numbers. To understand the mechanisms underlying numerical ability, the scientists minimized the influence of continuous magnitudes in numerical tests and conducted meticulous quantitative analyses to determine the respective contributions of numbers and magnitudes. They developed an algorithm to generate stimuli that enable animals to focus only on numbers, minimizing other distracting factors.
Rats demonstrate a capacity for numerical understanding; and specific brain regions, particularly the posterior parietal cortex, are crucial for this ability.
The study found that rats without any previous knowledge of numbers were able to develop a sense of them when trained with sounds representing two or three numbers. Despite the influence of continuous magnitudes, the rats consistently focused on the number of sounds when making choices for food rewards.
The scientists, who published their results in the scientific journal Science Advances in February 2024, discovered that when they blocked a specific part of the rats’ brains, called the posterior parietal cortex, their ability to understand numbers was affected but not their sense of magnitude. This suggests that the brain has a specific area for dealing with numbers. In fact, this is the first time scientists have demonstrated that rats can discriminate and categorize three different numbers in a single test, surpassing a simple quantity comparison.
The researchers state that their study helps dissect the relationship between magnitude and numeric processing. It not only solves a long-standing mystery about how brains handle numbers but also offers new insights into studying the specific neural circuits involved in number processing in animals and how genes are associated with mathematical ability. Furthermore, the findings from neural-network modeling could have practical applications in the field of artificial intelligence. In the future, our increased understanding of the brain mechanisms underlying the processing of numbers may contribute to the development of interventions for individuals with numerical difficulties.
In the future, increased understanding of the brain mechanisms underlying the processing of numbers may contribute to the development of interventions for individuals with numerical difficulties.
Mosquitofish show how intelligence evolved
High cognitive ability was recently demonstrated in another member of the animal kingdom: mosquitofish. According to scientists from The Australian National University and colleagues in Germany and South Africa, male mosquitofish possess impressive problem-solving skills and can successfully navigate mazes and other tests.
The lead author of the study postulates that male mosquitofish evolved better cognitive abilities over time because of the advantage it gave them in finding females and producing offspring—a phenomenon known as “sexual selection.”
Evolution of intelligence in animals has long been thought to have been driven by natural selection. Animals that were better at problem-solving were more adept at gathering food, finding shelter, avoiding predators and, hence, living longer. They then passed on these genes to their offspring, helping future generations become smarter over time.
Mosquitofish show us that there is an explanation for the evolution of intelligence other than natural selection: braininess is an attractive quality to the opposite sex, known as “sexual selection.”
But there is another explanation for the evolution of intelligence: braininess is an attractive quality to the opposite sex. A better brain might help an animal find more mates, have more sex and, eventually, have more babies. This suggests that intelligence in mosquitofish partly evolved through sexual selection, where traits that boost mating and fertilization success become more common over generations. Sexual selection is usually stronger in males than females because in most species, there are more males seeking mates than females ready to mate and breed.
The researchers measured the intelligence of the male mosquitofish by putting them through a series of underwater tests, including navigating mazes, detouring around transparent barriers and learning to remember differently colored spots—offering rewards to the fish that were able to complete the tests. Then, over a two-month period, the team tracked how many offspring each male produced when competing against other males for a female mating partner.
After performing more than 2,000 paternity tests, the scientists found that the smarter males who successfully navigated the underwater tests mated with more females and produced more offspring than the less intelligent fish that failed the tests.
Living in complex social groups is one of the keys to the evolution of big brains. But even though spotted hyenas can live in clans of up to 90 individuals, they spend much of their days in smaller, more vulnerable groups.
This study, the results of which were published in the journal Nature Ecology and Evolution in February 2025, indicates that intelligence in mosquitofish isn’t only driven by their need to find food or avoid predators, but also by the complex challenges of “finding love.” Something about these males seemingly gave them an edge in securing mating opportunities. Perhaps females recognized and preferred smarter males; or maybe smarter males were better at chasing the females and forcing them to mate, a common practice in mosquitofish.
Hyenas reveal that counting determines whether they fight or flee
Counting proficiency helps spotted hyenas decide whether to fight or flee, according to researchers at Michigan State University (MSU). When animals fight, the larger group tends to win.
In a paper published in the journal Animal Behaviour in October 2011, an MSU graduate student studying zoology showed that hyenas listen to the sound of intruders’ voices to determine who has the advantage. They’re more cautious when they’re outnumbered and take more risks when they have the numerical advantage.
When researchers played recordings of potential intruders, groups of three or more spotted hyenas were far more likely to approach the source of sound than pairs or individuals. Hyenas appear to count and to be as capable as chimpanzees or lions at assessing their advantage in numbers.
The finding supports the concept that living in complex social groups—as hyenas, chimpanzees and lions do—is one of the keys to the evolution of big brains.
Even though spotted hyenas live in clans of up to 90 individuals, they spend most of their time in smaller, more vulnerable groups. When researchers played recordings of potential intruders, the hyenas’ reactions depended on how many voices they heard compared to how many fellow pack members surrounded them. Groups of three or more hyenas were far more likely to approach the source of the sounds than pairs or individuals.
This study was the first to show that hyenas can tell the difference between individual voices, and most of the animals in the study could distinguish up to three unique ones. Even though the voices were unfamiliar—they came from hyenas in Kenya and in other African countries—the hyenas in the study were able to tell when they were from the same or different animals.
Humans are but one of many species armed with a propensity for calculation and counting. Domestic animals understand quantities—like how many treats in a day they are due.
Numerous kinds of animals exhibit a knack for numbers
A basic understanding of numbers is not unique to humans but is present in many animal species. Scientists have found that a wide range of animals have a keen sense of quantity and are able to distinguish not just bigger from smaller or more from less, but two from four, four from 10, and even 40 from 60.
Domestic animals, too, like my dog, prove that they understand quantities—like if the number of treats I give her at any one time is enough.
Here’s to finding your true places and natural habitats,
Candy
