Cats are known for the whiskers on their faces. However, if you look closely, you can see that they also have whiskers on their legs. So why do cats have leg whiskers?
To answer why they're useful, it's important to understand what whiskers are. Technically known as vibrissae, whiskers are specialized hairs that are stiffer and several times thicker than other hairs. Although whiskers themselves do not contain nerves, their bases are rooted in specialized receptacles loaded with nerve endings, making whiskers very sensitive.
"Facial whiskers are as sensitive as human fingertips," Robyn Grant, a sensory biologist at Manchester Metropolitan University in the U.K., told Live Science.
A cat's whiskers around the nose, which are also known as the mystacial vibrissae, are the longest whiskers they have, according to the veterinary reference book "The Feline Patient" (Wiley, 2025). Although there is variation among cats, on average there are 12 mystacial whiskers set in four rows on each side of the muzzle.
Cat leg whiskers, scientifically known as carpal vibrissae, are attached to their forelegs. (Image credit: Future)
Facial whiskers help cats hunt when light is limited or when their vision is poor. Although cats are good at seeing distant objects, "cats can't really focus on anything less than 10 inches (25 centimeters) from their eyes, so they use their whiskers to figure out where things are," Jonathan Losos, an evolutionary biologist at Washington University in St. Louis and author of "The Cat's Meow: How Cats Evolved from the Savanna to Your Sofa" (Viking, 2023), told Live Science.
In addition, cats have a tuft of whiskers known as superciliary vibrissae above each eye. These whiskers help protect the cat's vision by triggering a blink when stimulated by anything that might fly into their eye, according to The Feline Patient.
Cats also have chin whiskers (mandibular vibrissae) and whiskers on each side of the head, between the ear and chin (genal vibrissae). These also help cats stay aware of the space around them.
Leg whiskers
Cats also possess a tuft of four to six whiskers on the back of each front leg, each about 0.8 to 1.2 inches (2 to 3 centimeters) long. These are known as carpal vibrissae.
"Carpal refers to the bones that, in humans, are in our wrists," Losos said. "Carpal whiskers are attached to cat forelegs near the carpal bones." However, in cats, the carpal bones are not located in the same place as the human wrist. Rather, they "are further up the leg, because cats essentially walk on their toes and not their palms," he explained.
Cats are not the only animals with carpal whiskers. "Most carnivores have them, and many rodents do, as do lemurs and armadillos," Losos said. "Dogs don't have them, but other canine species do. Rabbits don't have them either, nor do ungulates — that is, hooved animals, such as horses and cattle."
The species that have carpal whiskers "tend to be the ones that either grasp things with their forelimbs or climb up trees," Losos said. "The idea is that if it's hard for the animals to see what they're grasping, carpal whiskers can help supplement their vision. Perhaps cats have them and dogs don't because cats can move their forearms laterally from side to side and put their palms together to grab things, whereas dogs can't."
It remains uncertain what role carpal whiskers play in cats, but they likely "guide locomotion — that is, safe forepaw placement — especially during complex locomotion, such as climbing," Grant said. "They might guide prey handling too."
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The spots on a leopard, the stripes on a zebra, and the mask on a raccoon are all types of coloration in mammal fur, referred to as pelage. Scientists have struggled for a long time to understand how these colorations evolved. A team of researchers recently discovered how to reconstruct the colors of ancient mammal fur using cell structures that contain the chemical pigment melanin, known as melanosomes. They hope to use this understanding of ancient mammal pelage to determine how they lived and what their environments were like.
To decipher the color of ancient mammal fur, the researchers constructed a statistical computer model to predict their fur colors based on the shape of their melanosomes. First, they needed to understand how the shapes of melanosomes control fur color in modern mammals. To measure the length and width of the modern melanosomes, the scientists used a beam of electrons like a flashlight to map them in great detail, a technique called scanning electron microscopy.
They measured the length and width of 2,615 melanosomes from the fur of 116 different living mammal species, including a Red Panda, a German Shepard, and one or more species of most types in the mammalian classification. Then they recorded the wavelengths of light reflected off each melanosome using a microspectrophotometer. These wavelengths represented the exact color of hair from each melanosome they measured. This means they now had a quantitative measurement of the color of each hair to compare with its corresponding melanosome length and width.
When they examined their data, the researchers found that spherical melanosomes produced brighter fur colors, like reds and oranges, while elongated melanosomes produced darker fur colors, like browns and grays. The researchers plotted the microspectrophotometric measurements for each melanosome as a graph showing how much light it absorbed across each possible wavelength, creating reflectance curves. Based on these data, the researchers used computer software to create a statistical model that could predict reflectance curves, and therefore color, from melanosome shape alone.
Once the researchers created a model, they needed to find fossilized mammal melanosomes to predict their fur color. Mammal fossils are rare, and pieces of cells are only preserved in the most immaculate fossil deposits. In fact, these researchers only found 6 fossils of this caliber, from Mesozoic rocks deposited around 250 million years ago, soon after mammals evolved.
The fossils came from 2 world-renowned deposits in Northeastern China, the Yanliao and Jehol biotas. They selected 5 previously studied fossils from these locations, including 1 specimen of Megaconus mammaliaformis, 1 specimen of Vilevolodon diplomylos, 2 specimens from the group Docodonta, and 1 specimen from the group Eutheria. All of these animals were small, rodent-like mammals. The researchers also discovered a new species of tree-dwelling mammal, Arboroharamiya fuscus.
The scientists used scanning electron microscopy to measure a total of 2,159 fossilized melanosomes to refine their color predictions. The fossilized melanosomes were all slightly elongated spheres and had far fewer differences in shape than in modern mammals. The researchers used their model to predict reflectance curves based on the shapes of the fossil melanosomes to determine the ancient mammals’ colors. They found that all the extinct mammals they examined likely had dark brown fur without any color patterns.
Based on these findings, the researchers suggested that most, if not all, early mammals were nocturnal, like many dark-colored mammals today. They suggested that this nocturnal lifestyle probably helped them survive the meteorite impact that wiped out the dinosaurs 100 million years later. While dinosaurs were unable to survive in the post-impact wasteland, these smaller, dark-colored mammals were more resilient and thrived in the aftermath. As mammals filled the ecological roles left by the dinosaurs, they evolved new color patterns, some based solely on camouflage, and others on new factors, like sexual selection and visual communication.
The researchers concluded that their model can predict fossilized mammal colors and help determine how these ancient animals lived. Notably, their data suggest that mammals likely stayed small and nocturnal throughout the Mesozoic until the dinosaurs were gone. Future researchers could use similar methods to uncover exactly how mammals evolved the colors we see today. For example, studying mammals closer to the impact event could reveal if it took a long time to develop diverse fur patterns, or if they began before the dinosaurs’ demise. Ultimately, similar studies could help determine whether the extinction of dinosaurs was necessary for the rise of mammals.
Monkeys use some of the same basic mental strategies as people do to perceive abstract relationships between shapes, a new study suggests.
The findings challenge the idea that humans crossed a sharp evolutionary divide when they learned to recognize geometric properties like symmetry, parallel lines and right angles, the researchers say.
"While humans do come up with geometric descriptions that are more abstract than what nonhumans can do, there's still some overlap, some similarity in the kinds of geometric intuitions you see in humans and those of non-primates," study co-author Jessica Cantlon, a professor of developmental neuroscience and psychology at Carnegie Mellon University, told Live Science. "So there's a thread of continuity that runs through geometric reasoning between humans and nonhumans."
The research, published July 20 in the journal PNAS, adds to a long-standing scientific debate over whether humans possess entirely unique forms of abstract thought or unusually sophisticated versions of abilities found elsewhere in the animal kingdom.
"For decades, cognitive scientists have searched for the 'special ingredient' that distinguishes human intelligence from that of other animals," Elizabeth Brannon, a professor of psychology at the University of Pennsylvania who was not involved in the research, told Live Science in an email. "This study provides compelling evidence that, at least for geometric reasoning, the difference between humans and other primates is more quantitative than qualitative."
In other words, the study suggested that baboons and macaques don't lack the ability to reason about geometry. Instead, they just aren't as proficient at it as humans, meaning that humans didn't evolve a new unique skill in understanding geometry.
A geometric matching game
The researchers tested eight adult monkeys: four rhesus macaques (Macaca mulatta) and four olive baboons (Papio anubis). The olive baboons participated through the Primate Portal, a touch-screen system installed at Seneca Park Zoo in Rochester, New York. One baboon, Kalamata, was especially enthusiastic.
"Every day he came to the touch screen," Jialin Li, a doctoral student at Carnegie Mellon University and first author of the study, told Live Science. "He just sat there and worked for two hours, three hours straight, completing thousands of trials. That's just amazing."
The macaques participated separately at Carnegie Mellon University, having prior experience with matching tests in other experiments.
The researchers then compared the animals' performance with that of 58 U.S. preschoolers ages 3 to 6, and 79 adults from the Tsimané, an Indigenous farmer-forager society in Bolivia whose members received little formal education. A separate experiment in the larger project involving rotating shapes also included 21 U.S. adults.
In all of the study's cohorts, the participants played a game known as a match-to-sample task.
"[The participants] see a sample shape first," Li said. "For example, it's a square. Then they need to tap the square to make sure that they are looking at it. When they tap it, there will be two shape choices that come up: one on the left and one on the right. They need to choose which shape matches with the sample shape."
The researchers made the choice shapes half the area of the sample shape, thus preventing the participants from solving the task by simply matching overall size or pixel count. In another version of the test, they rotated the choice shapes, thereby forcing the participants to identify the underlying form despite its changed orientation.
Two olive baboons participated in the Primate Portal experiments at the Seneca Park Zoo in Rochester, New York. (Image credit: Rochester Institute of Technology)
Correct answers earned the monkeys fruit-flavored cereal pellets, preschoolers collected stickers that could later be exchanged for prizes, and adults received verbal feedback. Incorrect answers triggered a "bonk" sound and a short timeout from the game.
Despite their limited formal education, the adult group had little trouble with the game, but the monkeys and the children had to put considerable thought into their choices.
"We often think that this matching task will be super easy for humans," Li said. "But actually, young kids were struggling in completing the task in telling the shapes apart, which makes them more similar to monkeys."
Ultimately, the children and monkeys could find the matches, Cantlon said, but only after taking a long time to think about the problem.
The researchers then used computer models to investigate which visual properties best predicted participants' decisions. One model represented simple details, such as edges and lines. Another represented more complex information about a shape's overall form. A third encoded discrete geometric properties, such as equal sides, equal angles, symmetry and parallelism — an approach the researchers described as "symbolic."
According to Cantlon and Li, the term "symbolic" does not mean the monkeys were mentally applying rules such as "a square has four equal sides." Much of the apparent symbolic effect could be explained by the ability to recognize a shape regardless of its orientation, known as rotation invariance.
If abstract geometry depended on a uniquely human symbolic system, only the human participants would have shown evidence of using that thought process. Instead, both monkeys and humans appeared to rely on a mixture of complex visual information and symbolic-like features. Adult humans generally performed the best, followed by preschoolers and monkeys, but their results overlapped. This finding suggests that the differences were quantitative, meaning humans are simply better at the same underlying kind of geometric reasoning rather than possessing an entirely unique ability., Monkeys relied roughly three times more strongly on the symbolic model when the shapes were rotated than when they remained upright.
Brandon said one of the study's most intriguing findings is that what looks like uniquely human symbolic reasoning for understanding geometry may actually grow out of flexible, abstract ways of representing information that are shared by humans and other primates.
Ancient roots of geometry
The results do not mean that monkeys understand formal mathematics, Brannon cautioned. "Human mathematical reasoning extends far beyond recognizing geometric regularities — it includes language, formal proof, recursive reasoning and cultural transmission."
Rather, this study provides evidence that some of the building blocks of mathematical thought have deeper evolutionary roots than previously recognized, she said.
Giorgio Vallortigara, a professor of neuroscience at the University of Trento in Italy who was not involved in the study, agrees with Brannon and her colleagues' conclusions.
Vallortigara explained in an email to Live Science that previous studies have often focused on how animals understand the geometry of their surroundings, such as navigating spaces. What makes these findings different is that they show animals can also reason about the geometric properties of individual objects.
Comparing species can help scientists trace the origins of geometry before language or arbitrary symbols became involved, Vallortigara said. It may also reveal whether similar abilities depend on mechanisms inherited from a common ancestor or evolved independently in animals with different nervous systems.
Li and Cantlon are now breaking down shapes into components such as angles, side lengths and numbers of sides to identify which properties are the hardest for monkeys and humans to understand. Cantlon described the follow-up as "a deconstructed geometry task."
The research could also help educators understand the geometric intuitions children bring into the classroom, Cantlon said, allowing lessons to build upon those abilities rather than treating geometry as something learned entirely from scratch.
"Evolution rarely invents entirely new mechanisms from scratch," Brannon said. "More often, it refines, recombines and extends existing ones."
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