People often feel compelled to respond to cats as they purr their requests at us. Weaving between our feet, rubbing against our legs, purring their low rumble, it’s clear what they want. Maybe you put that bowl down quickly so you won’t be tripped. But did you know that without the tripping hazard of the weaving and rubbing, even without seeing your cat, you may still feel compelled to respond to her purr?

A cry embedded within the purr

A while back, researchers found that cats have a “cry embedded within the purr.” This was the title of a research paper by Karen McComb and colleagues, who found that while cats beg for their food, their purrs actually contain an auditory component strikingly similar to a hungry human infant’s cry. It’s a sound that we have evolved to respond to quickly. Whether you’ve raised children or not, your brain knows this sound. And cats are using it to get what they want.

In addition to analyzing the auditory nature of the calls, the researchers played recordings of purrs associated with feeding requests and purrs from other situations (like petting) to people who were completely naive to the research question. People, regardless of their experience with cats, perceived the solicitation purrs to have more urgency and be less pleasant. The perception of the purrs as unpleasant is key; cats basically send us a signal that we want to cease, and we do so by giving them what they want. The demanding signal is just packaged in a pretty purr.

Can you hear the difference?

Below are recordings provided by the researchers in the original article. Can you hear the difference?

Listen to the solicitation purr.

Listen to the non-solicitation purr.

Why the hidden message?

You may be thinking that you love your cat, you just want him or her to feel content and that’s why you feed them. That makes sense too. I hope that’s why I fed my babies. But this type of urgent signaling certainly ensures the feeding comes in a timely fashion, doesn’t it? You’re unlikely to get distracted or do something else, aren’t you? It’s sort of like added insurance that one of their most important needs, one that is dependent on others, will be met.

The hidden cry is yet another neat example of how two species with a shared evolutionary history communicate. Considering how animals communicate their emotions, and why and how we respond to them, can help us understand how to better care for them. If you’re interested in human-animal communication, you may like the post about cats communicating with us through blinks, the post about the unknown thoughts of a barking dog, or the post about how human-dog communication can go awry and create a risky situation.

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Some readers of this blog have had to say goodbye to their cats in recent months. This post is dedicated to those cats and their people.

Article

McComb, K., Taylor, A. M., Wilson, C., & Charlton, B. D. (2009). The cry embedded within the purr. Current Biology, 19 (13), R507-R508. Link to article.