Licking

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Licking is the action of passing the tongue over a surface, typically either to deposit saliva onto the surface, or to collect liquid, food or minerals onto the tongue for ingestion, or to communicate with other animals. Many animals both groom themselves, eat or drink by licking.

Contents

In animals

Grooming: Animals commonly clean themselves through licking. In mammals, licking helps keep the fur clean and untangled. The tongues of many mammals have a rough upper surface that acts like a brush when the animal licks its fur. Certain reptiles, such as geckos, clean their eyes by licking them.

Mammals typically lick their offspring clean immediately after birth; in many species this is necessary to free the newborn from the amniotic sac. The licking not only cleans and dries the offspring's fur, but also stimulates its breathing and digestive processes.

Food and water acquisition: Hummingbirds are often said to "sip" nectar, but in fact they lap up nectar on their long tongues. Their tongues have fringed edges, which help both in nectar-eating and in catching tiny insects. Mother hummingbirds also lick their chicks after a rainstorm to dry them by licking water droplets from the coats of the chicks to avoid them chilling. Many animals drink by licking. While young mammals drink milk from their mothers' teats by sucking, the typical method of drinking for adult mammals involves dipping the tongue repeatedly into water and using it to scoop water into the mouth. This method of drinking relies in part on the water adhering to the surface of the tongue and in part on muscular control of the tongue to form it into a spoonlike shape.[ citation needed ] Cattle, horses and other animals lick rocks, salt licks or other objects to obtain mineral nutrients.

Gustation: Animals also use their tongues to enhance their sense of smell. By licking a surface or extending the tongue beyond the mouth, molecules are transferred via the tongue to the olfactory receptors in the nose and in some animals, to the vomeronasal organ. In some mammals, the tongue is used to "lick" the air during the flehmen response to assist transfer of pheremones. Similarly, snakes use smell to track their prey. They smell by using their forked tongues to collect airborne particles, then passing them to the vomeronasal organ. They keep their tongues constantly in motion, sampling particles from the air, ground, and water, analyzing the chemicals found, and determining the presence of prey or predators in the local environment.

Communication: Dogs and cats use licking both to clean and to show affection among themselves or to humans, typically licking their faces. Many animals use licking as a submissive or appeasement signal in dominance hierarchies.

Thermoregulation: Some animals use licking to cool themselves. Cats [2] do not sweat the way humans do and the saliva deposited by licking provides a similar means of evaporative cooling. Some animals spread saliva over areas of the body with little or no fur to maximise heat loss. For example, kangaroos lick their wrists and rats lick their testicles.

Mating behavior: Post-copulatory genital grooming often occurs in male rats and prosimian primates. [3] This behavior may prevent disease transmission. [4]

In primates

Ring-tailed lemurs lick each other's babies as a means of collective grooming and of reinforcing social cohesion within the community. [5] Macaques and other primates lick leaves for water in addition to dipping their arms into tree crevices and licking the water off. [6] Chimpanzees use licking in a variety of ways: licking objects, such as dead trees, that others in their community have licked, [7] licking each other's body parts for grooming and sex [7] and licking rocks for salt. [8] Gorillas use licking in addition to other senses to determine the nature of an object. [9]

In humans

Compared to most other mammals, licking has a minor role for humans. The human tongue is relatively short and inflexible, and is not well adapted for either grooming or drinking. Instead, humans prefer to wash themselves using their hands and drink by sucking or pouring fluid into their mouth. Humans have much less hair over their skin than most other mammals, and much of that hair is in places which they cannot reach with their own mouth. The presence of sweat glands all over the human body makes licking as a cooling method unnecessary.

Nonetheless, licking does play a role for humans. Even though humans cannot effectively drink water by licking, the human tongue is quite sufficient for licking more viscous fluids. Some foods are sold in a form intended to be consumed mainly by licking, e.g. ice cream cones and lollipops. Though useful, in some cultures it is considered improper table manners to clean one's fingers by licking during a meal.

Some people in the Afar tribe of Ethiopia have been reported to have used their tongues to lick other humans, as a way of cleaning them from the dust that accumulates on them in a very water-scarce region. [10] [ failed verification ]

Humans use licking for a number of other purposes. For example, licking can moisten the adhesive surfaces of stamps or envelopes. Many people lick a fingertip (usually the one of the index finger) for some extra grip when turning a page, taking a sheet of paper from the top of a pile or opening a plastic bag. In sewing, thread ends are commonly wet by licking to make the fibres stick together and thus make threading them through the eye of a needle easier. Another practice considered uncivilized is licking one's hand and using it to groom one's hair.

Humans also use their tongues for sexual purposes, such as during cunnilingus, anilingus, fellatio, breast licking, [11] foot licking, and whilst French kissing, where two people lick each other's tongues.

In dogs

This section is an excerpt from Dog communication § Licking and sniffing.[ edit ]
Licking behavior has multiple causes and meanings and should not be simply interpreted as affection. Dogs that are familiar with each other may lick each other's faces in greeting, then sniff any moist membranes where odors are strongest (i.e. mouth, nose, anal region, or urogenital region.) Mating behaviors are characterized by licking in a more vigorous manner than used during greetings. [12] : 124  Licking can communicate information about dominance, intentions, and state of mind, and, like the yawn, is mainly a pacifying behavior. All pacifying behaviors contain elements of puppy behavior, including licking. Puppies lick themselves and their litter-mates as part of the cleaning process, and it appears to build bonds. Later in life, licking ceases to be a cleaning function and forms a ritualized gesture indicating friendliness. [12] : 124–125  When stressed, a dog might lick the air, its own lips, or drop down and lick its paws or body. [12] : 126 Lip-licking and sniffing are also recognized as calming signals. [13]

Abnormal licking

Lick granuloma on a dog's paw Canine lick granuloma.jpg
Lick granuloma on a dog's paw

Self-licking can sometimes become abnormally frequent [14] occasionally resulting in a lick granuloma. The most common cause of lick granuloma appears to be psychological, related to stress, anxiety, separation anxiety, boredom, or compulsiveness. Lick granulomae are especially seen in active dogs left alone for long periods of time. One theory is that excessive licking causes endorphin release, which reduces pain and makes the dog feel temporarily euphoric. This provides the animal with positive feedback from the licking, and subsequent addiction to the behaviour.

Animals in captivity sometimes develop a licking stereotypy during which surfaces (walls, bars, gates, etc.) are repeatedly licked for no apparent reason. This has been observed in captive giraffes and camels. [15] [16]

Related Research Articles

<span class="mw-page-title-main">Lorisidae</span> Family of primates

Lorisidae is a family of strepsirrhine primates. The lorisids are all slim arboreal animals and comprise the lorises, pottos and angwantibos. Lorisids live in tropical, central Africa as well as in south and southeast Asia.

<span class="mw-page-title-main">Drinking</span> Ingestion of water or other liquids

Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among other animals.

<span class="mw-page-title-main">Vomeronasal organ</span> Smell sense organ above the roof of the mouth

The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth in various tetrapods. The name is derived from the fact that it lies adjacent to the unpaired vomer bone in the nasal septum. It is present and functional in all snakes and lizards, and in many mammals, including cats, dogs, cattle, pigs, and some primates. Some humans may have physical remnants of a VNO, but it is vestigial and non-functional.

<span class="mw-page-title-main">Strepsirrhini</span> Suborder of primates

Strepsirrhini or Strepsirhini is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Collectively they are referred to as strepsirrhines. Also belonging to the suborder are the extinct adapiform primates which thrived during the Eocene in Europe, North America, and Asia, but disappeared from most of the Northern Hemisphere as the climate cooled. Adapiforms are sometimes referred to as being "lemur-like", although the diversity of both lemurs and adapiforms does not support this comparison.

<span class="mw-page-title-main">Lemur</span> Clade of primates endemic to the island of Madagascar

Lemurs are wet-nosed primates of the superfamily Lemuroidea, divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to the island of Madagascar. Most existing lemurs are small, have a pointed snout, large eyes, and a long tail. They chiefly live in trees and are active at night.

<span class="mw-page-title-main">Ring-tailed lemur</span> A large lemur from Madagascar

The ring-tailed lemur is a medium- to larger-sized strepsirrhine (wet-nosed) primate, and the most internationally-recognized lemur species, owing to its long, black-and-white, ringed tail. It belongs to Lemuridae, one of five lemur families, and is the only member of the Lemur genus. Like all lemurs, it is endemic to the island of Madagascar, where it is endangered. Known locally in Malagasy as maky or hira, it ranges from gallery forests to spiny scrub in the southern regions of the island. It is omnivorous, as well as the most adapted to living terrestrially of the extant lemurs.

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

Grooming is the art and practice of cleaning and maintaining parts of the body. It is a species-typical behavior.

<span class="mw-page-title-main">Ruffed lemur</span> Genus of primates from Madagascar

The ruffed lemurs of the genus Varecia are strepsirrhine primates and are the largest extant lemurs within the family Lemuridae. Like all living lemurs, they are found only on the island of Madagascar. Formerly considered to be a monotypic genus, two species are now recognized: the black-and-white ruffed lemur, with its three subspecies, and the red ruffed lemur.

<span class="mw-page-title-main">Red ruffed lemur</span> Species of mammal native to Madagascar

The red ruffed lemur is one of two species in the genus Varecia, the ruffed lemurs; the other is the black-and-white ruffed lemur. Like all lemurs, it is native to Madagascar. It occurs only in the rainforests of Masoala, in the northeast of the island. It is one of the largest primates of Madagascar with a body length of 53 cm, a tail length of 60 cm and a weight of 3.3–3.6 kg. Its soft, thick fur is red and black in color and sports a buff or cream colored spot at the nape, but a few are known to have a white or pink patch on the back of the limbs or digits and a ring on the base of the tail in a similar color.

<span class="mw-page-title-main">Masoala fork-marked lemur</span> Species of lemur

The Masoala fork-marked lemur, also known as the eastern fork-marked lemur or Masoala fork-crowned lemur, is a species of lemur found in the coastal forests of northeastern Madagascar. It is a small nocturnal animal with large eyes, greyish fur and a long tail.

<span class="mw-page-title-main">Wound licking</span> Instinctive response in humans and many animals

Wound licking is an instinctive response in humans and many other animals to cover an injury or second degree burn with saliva. Dogs, cats, small rodents, horses, and primates all lick wounds. Saliva contains tissue factor which promotes the blood clotting mechanism. The enzyme lysozyme is found in many tissues and is known to attack the cell walls of many gram-positive bacteria, aiding in defense against infection. Tears are also beneficial to wounds due to the lysozyme enzyme. However, there are also infection risks due to bacteria in the mouth.

<span class="mw-page-title-main">Toothcomb</span> Dental structure found in some mammals

A toothcomb is a dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming, similar to a hair comb. The toothcomb occurs in lemuriform primates, treeshrews, colugos, hyraxes, and some African antelopes. The structures evolved independently in different types of mammals through convergent evolution and varies both in dental composition and structure. In most mammals the comb is formed by a group of teeth with fine spaces between them. The toothcombs in most mammals include incisors only, while in lemuriform primates they include incisors and canine teeth that tilt forward at the front of the lower jaw, followed by a canine-shaped first premolar. The toothcombs of colugos and hyraxes take a different form with the individual incisors being serrated, providing multiple tines per tooth.

<span class="mw-page-title-main">Stereotypy (non-human)</span> Non-pathological pattern of animal behavior which displays very low variability

In animal behaviour, stereotypy, stereotypic or stereotyped behaviour has several meanings, leading to ambiguity in the scientific literature. A stereotypy is a term for a group of phenotypic behaviours that are repetitive, morphologically identical and which possess no obvious goal or function. These behaviours have been defined as 'abnormal', as they exhibit themselves solely in animals subjected to barren environments, scheduled or restricted feedings, social deprivation and other cases of frustration, but do not arise in 'normal' animals in their natural environments. These behaviours may be maladaptive, involving self-injury or reduced reproductive success, and in laboratory animals can confound behavioural research. Stereotypical behaviours are thought to be caused ultimately by artificial environments that do not allow animals to satisfy their normal behavioural needs. Rather than refer to the behaviour as abnormal, it has been suggested that it be described as "behaviour indicative of an abnormal environment".

<span class="mw-page-title-main">Sublingua</span> Secondary tongue found in some primates

The sublingua ("under-tongue") is a muscular secondary tongue found below the primary tongue in tarsiers and living strepsirrhine primates, which includes lemurs and lorisoids. Although it is most fully developed in these primates, similar structures can be found in some other mammals, such as marsupials, treeshrews, and colugos. This "second tongue" lacks taste buds, and in lemuriforms, it is thought to be used to remove hair and other debris from the toothcomb, a specialized dental structure used to comb the fur during oral grooming.

The Bangka slow loris is a strepsirrhine primate and a species of slow loris that is native to southwestern Borneo and the island of Bangka. Originally considered a subspecies or synonym of the Bornean slow loris (N. menagensis), it was promoted to full species status in 2013 when a study of museum specimens and photographs identified distinct facial markings, which helped to differentiate it as a separate species. It is distinguished by the crimson red fur on its back, light-colored facial features, as well as the shape and width of the stripes of its facial markings.

<i>Nycticebus borneanus</i> Species of primate

Nycticebus borneanus, the Bornean slow loris, is a strepsirrhine primate and a species of slow loris that is native to central south Borneo in Indonesia. Formerly considered a subspecies or synonym of N. menagensis, it was promoted to full species status in 2013 when a study of museum specimens and photographs identified distinct facial markings, which helped to differentiate it as a separate species. It is distinguished by its dark, contrasting facial features, as well as the shape and width of the stripes of its facial markings.

<span class="mw-page-title-main">Comfort behaviour in animals</span>

Comfort behaviours in animals are activities that help maintain the pelage, feathers, integuement or musculoskeletal system and increase the physical comfort of the animal.

<span class="mw-page-title-main">Non-reproductive sexual behavior in animals</span> Non-reproductive behavior in non-human animals

Non-reproductive sexual behavior consists of sexual activities animals participate in that do not lead to the reproduction of the species. Although procreation continues to be the primary explanation for sexual behavior in animals, recent observations on animal behavior have given alternative reasons for the engagement in sexual activities by animals. Animals have been observed to engage in sex for social interaction bonding, exchange for significant materials, affection, mentorship pairings, sexual enjoyment, or as demonstration of social rank. Observed non-procreative sexual activities include non-copulatory mounting, oral sex, genital stimulation, anal stimulation, interspecies mating, and acts of affection, although it is doubted that they have done this since the beginning of their existence. There have also been observations of sex with cub participants, same-sex sexual interaction, as well as sex with dead animals.

Several non-human animal species are said to engage in apparent recreational drug use, that is, the intentional ingestion of psychoactive substances in their environment for pleasure, though claims of such behavior in the wild are often controversial. This is distinct from zoopharmacognosy, in which animals ingest or topically apply non-food substances for their health benefits, as a form of self-medication.

<span class="mw-page-title-main">Horse tongue</span> Anatomy of the equine tongue

The horse tongue, like that of most mammals, is pink in color and plays an important role in taste perception. With its long, narrow shape typical of herbivorous animals, it enables the horse to grasp its vegetable food, with the help of its lips and teeth. This tongue is sensitive to pressure and temperature, and is involved in licking and chewing behaviors. Although the mare licks its foal for a long time immediately after birth, there is little research into the gustatory sensitivity of horses and the social use these animals make of their tongues.

References

  1. ↑ L. David Mech; Luigi Boitani (1 October 2010). Wolves: Behavior, Ecology, and Conservation. University of Chicago Press. ISBN   978-0-226-51698-1.
  2. ↑ Cats and Kittens Magazine, Frequently Asked Cat Questions: Behavior Archived April 22, 2006, at the Wayback Machine . URL visited 8 April 2006.
  3. ↑ Peter M. Kappeler; Carel P. van Schaik (13 May 2004). Sexual Selection in Primates: New and Comparative Perspectives. Cambridge University Press. ISBN   978-1-139-45115-4.
  4. ↑ Frans B. M. De Waal; Peter L Tyack (June 2009). Animal Social Complexity: Intelligence, Culture, and Individualized Societies. Harvard University Press. ISBN   978-0-674-03412-9.
  5. ↑ Primate Factsheets: Ring-tailed lemur (Lemur catta) Behavior. Pin.primate.wisc.edu. Retrieved on 2013-03-30.
  6. ↑ Laboratory Primate Newsletter Volume 32 Number 1. Brown.edu. Retrieved on 2013-03-30.
  7. 1 2 楽天が運営するポータルサイト ： 【インフォシーク】Infoseek Archived 2006-04-09 at the Wayback Machine . Mahale.web.infoseek.co.jp (2000-01-01). Retrieved on 2013-03-30.
  8. ↑ Week Five. Personal.umich.edu (1996-10-09). Retrieved on 2013-03-30.
  9. ↑ Film Footage Search Results. lastrefuge.co.uk
  10. ↑ African People & Culture. africaguide.com.
  11. ↑ Pakpahan, Cennikon; Darmadi, Darmadi; Agustinus, Agustinus; Rezano, Andri (2022-07-21). "Framing and understanding the whole aspect of oral sex from social and health perspectives: a narrative review". F1000Research. 11: 177. doi: 10.12688/f1000research.108675.3 . ISSN   2046-1402.
  12. 1 2 3 Coren, Stanley (2012). How To Speak Dog. New York: Simon and Schuster. ISBN   9781471109416.
  13. ↑ Rugaas, Turid (2006). On talking terms with dogs : calming signals (2nd ed.). Wenatchee, Wash.: Dogwise Pub. ISBN   1929242360.
  14. ↑ "Obsessive-Compulsive Behavior: Chewing, Licking, Fur-Pulling". About.Com. Retrieved September 10, 2013.
  15. ↑ "Zoochosis". Circus Watch W.A. Archived from the original on September 4, 2013. Retrieved September 10, 2013.
  16. ↑ Video of a giraffe licking wall
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