Any pet owner will tell you it’s a not a question worth asking. We already know our cats and dogs have personalities all their own. Different animals behave and react differently when placed in different situations. The way they grow up matters. Their human make a big difference. Whether or not they’re around other pets makes a big difference. Big changes in environment make a big difference. Okay, so they have different personalities, but what does the science say?
Probably more than you’d expect. Personality traits aren’t unique to our pets. Character traits have been observed throughout the animal kingdom. Fish. Monkeys. Birds. Even hermit crabs. All of these animals can have unique personalities. It’s easy enough to observe, but harder to measure and categorize. Humans can take quizzes and surveys online (even though we would argue that these are always skewed one way or another by the person’s bias). Animals can’t.
Researchers use animal behaviors to determine what kind of personality is being observed. For example, a basic interaction between a member of an animal species is observed. It might interact with another member of the same species, or it might interact with a rock. Based on the collective behaviors of other members of the same species an animal might be categorized as bold or timid or docile, or any number of other easily understood traits.
Like humans, however, these traits can be dependent on mood or experience. Scientists have noticed that fish who are involved with a violent struggle with other fish might learn to avoid similar situations in the future. When once they were bold, they have learned discretion is the better part of valor and evolved to become timid or shy, avoiding future interactions with the same type of fish.
These traits also guide how animals interact with the environment around them. This means that an aggressive animal might experience the risks and rewards of its environment very differently than a gentle animal. Although it’s difficult to measure the extent to which genes factor into personality expression, we know they do.
Of course, these categorizations don’t do the animals any justice. Each human is unique. We act differently and we think differently. We each have our unique quirks. So do the animals we love so much!