Cats’ reputation for being aloof and truly not caring about their owners doesn’t really tell the whole story. This suggests that they can identify which humans are familiar to them just by smell. Whether or not they can use scent to tell humans apart had previously not been studied. The team from Tokyo University of Agriculture in Japan investigated whether domestic cats can just use smell to distinguish between familiar and unfamiliar humans. Later, they switched to their left nostril as they became more familiar with the smell.