One of the biggest differences between domestic cats and their wild relatives lies in their vocalizations. Most large cat species, such as lions and tigers, can roar loudly across the wilderness to announce their presence and defend their territory. However, domestic cats produce a relatively “soft” and less aggressive sound.
The answer to this issue relates to the larynx and throat of cats, which allow them to create their characteristic sounds. John Wible, head of mammals at the Carnegie Museum of Natural History in Pittsburgh, USA, states that the different vocalizations in cats arise from the way they produce roars and purrs, with these sounds being mutually exclusive in cats. This means that any cat species can produce one of these two sounds, but not both.
Rare roaring in cats has evolved in a specific large cat species.
Purring is a unique sound because it is produced both when a cat inhales and exhales. Wible suggests that this sound seems to have first developed in cats and is common within the Felidae family. Cats that purr include domestic cats, bobcats, servals, and cheetahs…
Meanwhile, roaring is rarer in cats and has evolved in specific large cat species. These cats make up the genus Panthera, which includes lions, tigers, leopards, and jaguars. An exception here is the snow leopard, a species that may have lost the ability to roar.
Similar to humans, the sounds that cats produce come from their larynx. The difference between purring and roaring in cats begins here, although the exact way cats produce these sounds is still unclear.
The larynx of mammals is located in the throat, where air passes through its structures to create sound. The hyoid bone and vocal cords are two essential parts of the larynx that produce a cat’s sounds.
Wible states that all mammal species have bones in their necks close to the lower jaw known as the hyoid apparatus, which connects to the base of the skull. This connection can occur directly or via ligaments. One significant difference between purring and roaring species lies in the hyoid structure.
In roaring cats, there is a unique arrangement with a pair of bones in the hyoid apparatus, known as epihyoid. Unlike bone, the epihyoid is an elastic ligament that extends. The soft, flexible cartilage allows roaring cats to lower their pitch in the throat, producing a deeper sound.
A notable difference between purring and roaring cats lies in the larynx. Purring is caused by extremely rapid contractions of the laryngeal muscles within the folds of the larynx. Roaring cats typically have longer, heavier, more flexible, and meatier vocal cords. According to a 2011 study, this tissue is robust and flexible, enabling large cats to produce the low-pitched rumble of a roar.
Wible states: “Regardless of the physiological developments that lead to the sounds of cats, they must confer some evolutionary advantages. Scientists are currently uncertain about the role of purring in the wild. Current hypotheses suggest that purring may be a healing or soothing mechanism or may help mask the mewing of kittens from predators. My domestic cats purr as a sign of contentment, but I don’t know if this holds true for purring cats in the wild.“
