A study found that cats can distinguish between their owners and strangers by smell.
A research team led by Hidehiko Uchiyama, a professor of animal science at Tokyo University of Agriculture, published the results of an experiment on whether cats can differentiate between their owners and strangers based solely on human scent in the international academic journal "PLOS One" on the 28th.
Cats are known to primarily communicate with other cats through scent. However, this is the first study to investigate whether they can recognize humans by smell. It has previously been shown that cats can differentiate human voices, interpret gaze to find food, and adjust their behavior based on human emotional states.
The research team conducted the experiment with 30 domestic cats. The cats were given plastic tubes containing swabs rubbed with the armpits, behind the ears, and between the toes of their owners or strangers.
The cats responded by sniffing the scent of strangers for a longer duration than that of their owners. This indicates that cats can distinguish between familiar and unfamiliar people based only on scent. Previously, it has been noted that weaned kittens tend to sniff the scent of unfamiliar female cats for a longer time compared to their mother.
Additionally, cats primarily used their right nostril when they first encountered unfamiliar scents, switching to their left nostril as they became accustomed to the smell. This phenomenon has previously been observed in dogs, fish, and birds. Professor Uchiyama explained, "This suggests that olfaction may be related to brain function," adding that "the right hemisphere appears to be preferred for processing emotionally surprising unfamiliar scents."
Male cats exhibited differences in sniffing behavior according to their personality. Nervous male cats tended to sniff repetitively, while those with a calm personality reacted relatively composedly. In contrast, female cats showed similar behaviors regardless of their personality.
The research team stated, "It appears that cats use olfaction to recognize humans," noting that cats exhibited rubbing behavior against the plastic tubes after sniffing, which may indicate that sniffing is the exploratory behavior before the display. They added, "However, more research is needed to determine if cats can recognize specific individuals by smell alone."
Carlo Siracusa, a professor at the University of Pennsylvania School of Veterinary Medicine, noted in The New York Times that "care should be taken to interpret the sniffing behavior of cats in relation to brain function," and that to prove that unfamiliar scents activate the right hemisphere, cats would need to cooperate in brain imaging while sniffing.
References
PLOS One (2025), DOI: https://doi.org/10.1371/journal.pone.0324016