University of Sussex, England, researchers have found that some cats have learned to purr in a particular way to get their human companions to do their bidding. This fits in with the oft-quoted fact that cats don't have owners - they have staff.
Communication across the Species Barrier
Dr. Karen McComb has set up the Centre for Mammal Vocal Communication Research with the aim of researching how various animals are able to exchange information across the species barrier. She and her colleagues have worked with elephants, deer, and lions, among other wild animals. They are also carrying out research with domestic pets.
Vocalizing in Cats
Felines are not the only animals that purr but they are the ones most associated with the behaviour. Gisela Telis writing for ScienceNow Daily News, (July 13, 2009) pointed out that “guinea pigs and even elephants can purr...The low rumble - at 27 Hz, it’s comparable to the lowest note on a piano - serves as a kind of smile, often indicating contentment. It also sometimes crops up when a cat is sick or injured, perhaps to reassure themselves, ask for help, or aid in their own healing.”
Cat Purring Similar to Baby’s Cry
Dr. McComb is a behavioural ecologist and she became interested in a particular purring sound her own cat Pepo used. He got into the habit of waking her early in the morning with a persistent purr, which she interpreted as a demand for breakfast.
Speaking to other cat owners, Dr. McComb found several whose feline friends had shown the same behaviour. It was noted that the cats added an extra, higher pitched sound to their purring that had a similar frequency to that of a crying human baby. Dr. McComb said this was “apparently exploiting inherent sensory biases that humans have for providing care.”
Most cat owners responded to this more insistent sound by filling up the animal’s food bowl.
Investigation into Cat Purring Set up
Writing for BBC News (July 13, 2009), science reporter Victoria Gill described the experiment Dr. McComb and her colleagues set up. “…Her team had to train cat owners to make recordings of their own cats’ vocal tactics - recording both their ‘soliciting purrs’ and regular, ‘non-soliciting’ purrs. ‘When we played the recordings to human volunteers, even those people with no experience of cats found the soliciting purrs more urgent and less pleasant,’ said Dr. McComb.”
Dr. McComb told the BBC that the higher frequency sound is part of a cat’s normal vocalizing, “But we think that (they) learn to dramatically exaggerate it when it proves effective in generating a response from humans.”
The results of the study have been published in Current Biology (July 14, 2009), where the research team write: “Embedded within the naturally low-pitched purr, we found a high frequency voiced component, reminiscent of a cry or meow, that was crucial in determining urgency and pleasantness ratings. Moreover, when we re-synthesized solicitation purrs to remove only the voiced component, paired presentations revealed that these purrs were perceived as being significantly less urgent.”
Rupert Taylor - Rupert Taylor is the editor of a magazine that provides background to current events.
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