The mystery of the cat's purr
Some experts say The purr is due to the vibrations of false vocal chords , two folds of membranes behind the real vocal chords. Others argue that purring is the direct result of the blood movement in the vena cava that returns blood to the heart after irrigating the entire body.
This vein, between the liver and the diaphragm, would be the origin of vibrations in the thorax and in the trachea. Be that as it may, purring is a means of communication: it is the very first form of communication between the mother and her kittens, as well as in the adult cat who also uses it with the man.
The purr when fighting
In adult cats, but also in big cats such as the lion and the cheetah, purring is often used when fighting with prey. We can only assume the reasons for this purr: it may be a legacy of what he learned in his first games with his mother, but it can also be a manifestation of satisfaction and happiness of the animal to the idea of having achieved its goal.
Some finally argue that the hum would have a hypnotic effect which the cat would use to to calm and kill prey
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