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If you've ever shared your home with more than one cat, you'll know how different their personalities can be. One might chirp for food, purr loudly on your lap and greet visitors at the door. Another might prefer quiet observation from a distance.

So why do some cats become chatty companions while others seem more reserved?

A led by wildlife researcher Yume Okamoto and their colleagues at Kyoto University suggests that part of the answer may lie in cat genes.

Cat owners from across Japan were asked to complete a questionnaire about their cat (the ), and to take a cheek swab from their pet to provide a DNA sample. The survey included questions about a range of cat behavior, including purring and vocalizations directed at people.

The researchers in the recent Japanese study focused on the cats' (AR) gene, located on the X chromosome. This gene helps regulate the body's response to hormones such as testosterone and contains a section where a DNA sequence is repeated. AR is an essential part of vertebrate biology.

The form of AR appeared in the common ancestor of all jawed vertebrates, over 450 million years ago. AR controls the formation of male reproductive organs, secondary sexual characteristics and . The number of these sequences alters how responsive the gene is. Shorter repeats make the receptor more sensitive to androgens. In other species, including humans and , shorter repeats in the AR gene have been linked with increased and .

Among 280 spayed or neutered cats, those with the short AR gene variant purred more often. Males with the variant also scored higher for directed vocalizations such as meowing to be fed or let out. Females with the same genotype, however, were more aggressive towards strangers. Meanwhile, cats with the longer, less active version of the gene tended to be quieter. This variant was more common in pedigree breeds, which are typically bred for docility.

Domestication is generally thought to have in cats, so it may seem odd that the version of the gene linked to increased communication and assertiveness is the one also found in wild species .

But this study doesn't tell a straightforward narrative about how cat domestication selects for sociable traits. Instead, it points to a more complex picture. One where certain ancestral traits like aggression may still be useful, especially in or resource-scarce domestic environments.

Some animals spend a lot of time around humans because they are attracted by our resources rather than bred as companion animals or farmed. Urban gulls offer an interesting example of how close proximity to humans doesn't always make animals more docile. In cities, herring and lesser black-backed gulls (both often referred to as seagulls) have become bolder and more aggressive.

Researchers at found that urban gulls were less fearful of humans and more prone to squabbling compared to their rural counterparts. In urban areas, where food is highly contested, being assertive gets results. Gulls are often press as urban villains, to snatch your lunch or chase pedestrians. This suggests that life alongside humans can sometimes favor more confrontational behavior.

The parallels with cats raise broader questions about how environment and genes shape behavior. Okamoto and colleagues' findings may reflect a trade-off. Traits linked to the short AR variant, such as greater vocalization or assertiveness, might offer advantages in gaining human attention in uncertain or competitive settings. But these same traits may also manifest as aggression, suggesting that domestication can produce a mix of desirable and challenging traits.

It's worth bearing in mind that this kind of variation between individuals is . Without variation in behavior, species would struggle to adapt to changing environments. For cats, this means there may be no single ideal temperament, but rather a range of traits that prove useful under different domestic conditions.

From cats to gulls, life alongside humans doesn't always produce gentler animals. Sometimes, a little pushiness pays off.

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