Purr

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Mechanism

The mechanism by which cats purr is an object of speculation, with different hypotheses proposed. An early idea was that purring is a hemodynamic process where sound is produced as the blood runs through the thorax. [4]

There is a unique "neural oscillator" in the cat's brain of uncertain significance. [5] Although the mechanism has not yet been fully explained, recent studies have inferred it could be the result of oscillatory mechanisms in the central nervous system. [6]  Studies have also shown that purring can be caused through electrically stimulating the infundibular region of the cat's brain, suggesting central control. [7]

Vocal folds/laryngeal muscles

One hypothesis, backed by electromyographic studies, is that cats produce the purring noise by using the vocal folds or the muscles of the larynx to alternately dilate and constrict the glottis rapidly, causing air vibrations during inhalation and exhalation. [8] Combined with the steady inhalation and exhalation of air as the cat breathes, a purring noise is produced with strong harmonics. [9]

Degree of hyoid ossification

No cat can both purr and roar. The subdivision of the Felidae into "purring cats" (Felinae) on one hand and "roaring cats" (Pantherinae) on the other goes back to Owen [10] and was definitively introduced by Pocock, [11] based on whether the hyoid bone of the larynx is incompletely ("roarers") or completely ("purrers") ossified. However, Weissengruber et al. argued that the ability of a cat species to purr is not affected by the anatomy of its hyoid. [12]

The "roaring cats" (lion, Panthera leo; tiger, P. tigris; jaguar, P. onca; leopard, P. pardus) have an incompletely ossified hyoid, which, according to this hypothesis, enables them to roar but not to purr. However, the snow leopard (Uncia uncia, or P. uncia), as the fifth felid species with an incompletely ossified hyoid, purrs. [13]

All remaining species of the family Felidae ("purring cats") have a completely ossified hyoid, which enables them to purr but not to roar. Based on a technical acoustic definition of roaring, the presence of this vocalization type depends on specific characteristics of the vocal folds and an elongated vocal tract, which is rendered possible by an incompletely ossified hyoid.

Frequency, amplitude, and respiratory variation

Purpose

In domestic cats, many signals that occur when interacting with humans seem to originate from when the animal was dependent on the mother. Cats have been observed to purr for most of their lifespan, starting from when they were young and suckling from their mother. [18] Purring may be a signaling mechanism of reassurance between mother cats and nursing kittens. Post-nursing cats often purr as a sign of contentment when being petted, becoming relaxed or eating. Some purring may be a signal to another animal that the purring cat does not pose a threat.

Cats have been shown to have different types of purrs depending on situations. For example, purring appears to be a way for cats to signal their caretakers for food. This purring has a high-frequency component not present in other purrs. These are called solicitation purrs (when the cat is seeking a result) and non-solicitation purrs, and the two are distinguishable to humans. In a study, 50 humans were subjected to playbacks of purrs recorded in solicitation and non-solicitation situations at the same amplitude. Humans regularly judged the solicitation purrs as less pleasant and more urgent than the non-solicitation purrs. [18]  This variety of purring seems to be found more frequently in cats in a one-to-one relationship with a caretaker. Similarities have been drawn between an infant's cry and the isolation cry of domestic cats. The high-frequency aspect of the purr may subtly exploit humans' sensitivity to these cries. Using sensory biases in communication between species provides cats with a productive means of improving the care that they receive. [18]

Cats often purr when distressed or in pain, such as during the three stages of labor. In the first stage, the uterus begins to contract, the cervix relaxes, the water breaks and the cat begins to purr, which is hypothesized to be a self-relaxation technique. This purring may trigger a cat's brain to release a hormone that helps it relax and acts as a painkiller. [19]

There is also some evidence that the frequency at which cats purr can help promote bone density and hasten healing. [20]

See also

Related Research Articles

<span class="mw-page-title-main">Cat</span> Small domesticated carnivorous mammal

The cat, commonly referred to as the domestic cat or house cat, is the only domesticated species in the family Felidae. Recent advances in archaeology and genetics have shown that the domestication of the cat occurred in the Near East around 7500 BC. It is commonly kept as a house pet and farm cat, but also ranges freely as a feral cat avoiding human contact. It is valued by humans for companionship and its ability to kill vermin. Because of its retractable claws, it is adapted to killing small prey like mice and rats. It has a strong, flexible body, quick reflexes, sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It also secretes and perceives pheromones.

<span class="mw-page-title-main">Felidae</span> Family of mammals

Felidae is the family of mammals in the order Carnivora colloquially referred to as cats. A member of this family is also called a felid. The term "cat" refers both to felids in general and specifically to the domestic cat.

<span class="mw-page-title-main">Cheetah</span> Large feline of the genus Acinonyx

The cheetah is a large cat and the fastest land animal. It has a tawny to creamy white or pale buff fur that is marked with evenly spaced, solid black spots. The head is small and rounded, with a short snout and black tear-like facial streaks. It reaches 67–94 cm (26–37 in) at the shoulder, and the head-and-body length is between 1.1 and 1.5 m. Adults weigh between 21 and 72 kg. The cheetah is capable of running at 93 to 104 km/h ; it has evolved specialized adaptations for speed, including a light build, long thin legs and a long tail.

Panthera is a genus within the family Felidae, it is one of two extant genera in the subfamily Pantherinae, and contains the largest living members of the cat family. There are 5 living species, the tiger, jaguar, lion, leopard and snow leopard and a number of extinct species.

The term "big cat" is typically used to refer to any of the five living members of the genus Panthera, namely the tiger, lion, jaguar, leopard, and snow leopard, as well as the non-pantherine cheetah and cougar.

<span class="mw-page-title-main">Hyoid bone</span> Bone situated in the neck between the chin and the thyroid cartilage

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical vertebra.

<span class="mw-page-title-main">Felinae</span> Subfamily of Felidae

Felinae is a subfamily of the Felidae and comprises the small cats having a bony hyoid, because of which they are able to purr but not roar. Other authors have proposed an alternative definition for this subfamily, as comprising only the living conical-toothed cat genera with two tribes, the Felini and Pantherini, and excluding the extinct sabre-toothed Machairodontinae.

<span class="mw-page-title-main">Felid hybrids</span> Hybrid carnivore

A felid hybrid is any of a number of hybrids between various species of the cat family, Felidae. This article deals with hybrids between the species of the subfamily Felinae.

<span class="mw-page-title-main">Pantherinae</span> Subfamily of felids

The Pantherinae is a subfamily of the Felidae; it was named and first described by Reginald Innes Pocock in 1917 as only including the Panthera species. The Pantherinae genetically diverged from a common ancestor between 9.32 to 4.47 million years ago and 10.67 to 3.76 million years ago.

<span class="mw-page-title-main">Rosette (zoology)</span> Rose-like markings on fur and skin

A rosette is a rose-like marking or formation found on the fur and skin of some animals, particularly cats. Rosettes are used to camouflage the animal, either as a defense mechanism or as a stalking tool. Predators use their rosettes to simulate the different shifting of shadows and shade, helping the animals to remain hidden from their prey. Rosettes can be grouped in clusters around other spots, or may appear as blotches on the fur.

<span class="mw-page-title-main">Cat communication</span> Feline means of sending or receiving information

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<span class="mw-page-title-main">Parc des Félins</span> Zoo in France

Parc des Félins is a zoological park in France dedicated to the breeding and conservation of wild members of the cat family. It is located in the commune of Lumigny-Nesles-Ormeaux in Seine-et-Marne, about 53.6 km (33.3 mi) southeast of Paris.

<span class="mw-page-title-main">Prusten</span>

Prusten is a form of communicative behaviour exhibited by some members of the family Felidae. Prusten is also referred to as chuffing or chuffle. It is described as a short, low intensity, non-threatening vocalization. In order to vocalize a chuff, the animal's mouth is closed and air is blown through the nostrils, producing a breathy snort. It is typically accompanied by a head bobbing movement. It is often used between two cats as a greeting, during courtship, or by a mother comforting her cubs. The vocalization is produced by tigers, jaguars, snow leopards, clouded leopards and even polar bears. Prusten has significance in both the fields of evolution and conservation.

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The snow leopard, occasionally called ounce, is a species of large cat in the genus Panthera of the family Felidae. The species is native to the mountain ranges of Central and South Asia. It is listed as Vulnerable on the IUCN Red List because the global population is estimated to number fewer than 10,000 mature individuals and is expected to decline about 10% by 2040. It is mainly threatened by poaching and habitat destruction following infrastructural developments. It inhabits alpine and subalpine zones at elevations of 3,000–4,500 m (9,800–14,800 ft), ranging from eastern Afghanistan, the Himalayas and the Tibetan Plateau to southern Siberia, Mongolia and western China. In the northern part of its range, it also lives at lower elevations.

In phonetics, ingressive sounds are sounds by which the airstream flows inward through the mouth or nose. The three types of ingressive sounds are lingual ingressive or velaric ingressive, glottalic ingressive, and pulmonic ingressive.

<span class="mw-page-title-main">Roar (vocalization)</span> Deep resonating sound produced by animals

A roar is a type of animal vocalization that is loud, deep and resonating. Many mammals have evolved to produce roars and other roar-like vocals for purposes such as long-distance communication and intimidation. These include various species of big cats, bears, pinnipeds, deer, bovids, elephants and simians.

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References

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Further reading