International Cat Day 2024: A study reveals the origin of cats’ purring
A new study performed by researchers at the University of Vienna challenges what was considered the only valid explanation for feline purring.
Cats’ purring is a sign that they are content, enjoying lots of fuss and attention. We all know that cats express their feelings by purring, in the same way that when humans are happy they smile and dogs wag their tails.
For the scientific community, the real mystery was how cats produce these purrs. The most accepted hypothesis about the origin of purring was that of muscle contraction. Muscle contractions make the vocal cords vibrate, generating the characteristic purring sound. However, this view is based on anatomical and physiological observations of cats, but there is no direct evidence to support it.
However, a study published in Current Biology seems to have found the answer: it is similar to snoring.
The study into a cats purring
A team of researchers from the University of Vienna led by Austrian scientist Christian T. Herbst proposed an alternative based on the myoelastic-aerodynamic theory.
This theory focuses on how sounds are generated by the flow of air through elastic structures in the larynx, without relying on muscle contractions. To carry out the study, the researchers used the larynxes extracted from eight domestic cats euthanized after terminal illnesses, and with full knowledge and acceptance by their owners.
Next, they compressed the vocal cords of the larynx and blew warm, moist air through them. By doing this, they ensured that any sounds generated did not come from muscle contraction or brain intervention.
The discovery has sparked some controversy among experts.
T. Herbst and his colleagues were able to observe that purring occurred in all the removed larynxes, with self-sustained oscillations at low frequencies between 25 and 30 hertz. The explanation lies in a special ‘pad’ embedded in the vocal cords of cats, and observable with the naked eye. Purring is thus a passive sound without need of any muscular effort.
The research team wanted to emphasize that their study does not seek to discredit the muscle contraction hypothesis, but rather to open a new avenue of research and highlight the need to review and delve deeper into which until now was considered the only valid explanation for feline purring.