LAnd cats purr they are one of the still unsolved mysteries concerning our beloved felines. Especially when a new authoritative study rearranges the cards and proposes a new theory.
Purring of cats, the mystery explained by a study
Until the day before yesterday we considered purring an expression of pleasure of the cat. Yesterday we understood that this is not always the case, and rather it is a purr a ruse which felines use to calm themselves in various situations, not necessarily positive ones. So even in stressful situations. But the belief that they were controlled by the brain remained firm.
Because purrs are exceptional
Purrs are in fact vibrations at low frequencies (between 20 and 30 hertz). And these frequencies are usually observed only in much larger animals, such as elephants, who have much longer vocal cords. For this reason the purr has long been considered exceptional. Research dating back to the 1970s taught us that purring is produced by a special mechanism. A cyclic contraction followed by relaxation of the muscles in the vocal cords within the larynx which requires constant neural input and, indeed, control by the brain. An active muscular contraction, therefore.
The new study on cat purring
Today a new study published in Current Biology reveals that this is not the case. Cats would have some sort of “pads” built into the vocal cords. Structures that would add an extra layer of fatty tissue thanks to which the vocal cords vibrate at low frequencies.
A cat with a biscuit coat fawns with a man and puts himself on caresses. Photo in home space
And this mechanism nowould not require any active contraction of the muscles: instead it occurs automatically after the initial input sent by the brain.
The study looked at the larynges of eight deceased cats: researchers at the University of Vienna observed that any sounds produced, including purring, occurred without repetitive muscle contractions or any cyclical neural input. Furthermore, from anatomical investigations, the team observed unusual masses of connective tissue embedded in the vocal cords, which could explain how such a small animal can produce sounds at such low frequencies.
Low frequency vibrations, cats like elephants
«It is possible that these “cushions” increase the density of the vocal cords, making them vibrate more slowly and allowing cats to produce low frequency sounds despite their relatively small size,” comments study author Christian T. Herbst.
The only doubt? David Rice raises it in Science, a biomechanical engineer at Tulane University, who has conducted several research on the mechanisms of cat purring. There is, according to him, no guarantee that the vocal cords of living cats will behave in the same way as those removed surgically, as in this study.
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