Post by sanjana on Aug 22, 2012 2:49:46 GMT -5
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication — sometimes called Zoosemiotics (defined as the study of sign communication or semiosis in animals; distinguishable from anthroposemiotics, the study of human communication) — has played an important part in the methodology of ethology, sociobiology, and the study of animal cognition.
Animal communication, and the understanding of the animal world in general, is a rapidly growing field. Even in the 21st century, many prior understandings related to diverse fields such as personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, have been revolutionized. * Gestures: The best known form of communication involves the display of distinctive body parts, or distinctive bodily movements; often these occur in combination, so a distinctive movement acts to reveal or emphasize a distinctive body part. For example, the presentation of a parent Herring Gull’s bill to its chick signals feeding time. Like many gulls, the Herring Gull has a brightly coloured bill, yellow with a red spot on the lower mandible near the tip. When it returns to the nest with food, the parent stands over its chick and taps the bill on the ground in front of it; this elicits a begging response from a hungry chick (pecking at the red spot), which stimulates the parent to regurgitate food in front of it. The complete signal therefore involves a distinctive morphological feature (body part), the red-spotted bill, and a distinctive movement (tapping towards the ground) which makes the red spot highly visible to the chick. Congruently, some cephalopods, such as the octopus, have specialized skin cells that can change the apparent colour, opacity, and reflectiveness of their skin.[1] In addition to being used for camouflage, rapid changes in skin colour are used while hunting and in courtship rituals.[2] While all primates use some form of gesture,[3] Frans de Waal came to the conclusion that apes and humans are unique in that only they are able use intentional gestures to communicate. He tested the hypothesis of gesture evolving into language by studying the gestures of bonobos and chimps.
* Facial expression: Facial gestures play an important role in animal communication. Dogs for example express anger through a snarling and showing their teeth. In alarm their ears will perk up. When fearful a dog will pull back their ears, expose teeth slightly and squint eyes. Jeffrey Mogil studied the facial expressions of mice during increments of increasing pain. What they found were five recognizable facial expressions; orbital tightening, nose and cheek bulge, and changes in ear and whisker carriage.[4]
* Gaze following: Coordination among social animals is facilitated by monitoring of each others' head and eye orientation. Long recognized in human developmental studies as an important component of communication, there has recently begun to be much more attention on the abilities of animals to follow the gaze of those they interact with, whether members of their own species or humans. Studies have been conducted on apes, monkeys, dogs, birds, and tortoises, and have focused on two different tasks: "follow[ing] another’s gaze into distant space" and "follow[ing] another’s gaze geometrically around a visual barrier e.g. by repositioning themselves to follow a gaze cue when faced with a barrier blocking their view". The first ability has been found among a broad range of animals, while the second has been demonstrated only for apes, dogs (and wolves), and corvids (ravens), and attempts to demonstrate this "geometric gaze following" in marmosets and ibis gave negative results. Researchers do not yet have a clear picture of the cognitive basis of gaze following abilities, but developmental evidence indicates that "simple" gaze following and "geometric" gaze following are likely to rely on distinct cognitive foundations.[5]
* Vocalization: Many animals communicate through vocalizations. Communication through vocalization is essential for many tasks including mating rituals, warning calls, conveying location of food sources, and social learning. Male mating calls are used to signal the female and to beat competitors in species such as hammer-headed bats, red deers, humpback whales and elephant seals.[6] In whale species Whale song has been found to have different dialects based on location.[7] Other instances of communication include the warning cries of the Campbell monkey,[8] the territorial calls of gibbons, the use of frequency in Greater Spear-nosed Bats to distinguish between groups.[9]
* Olfactory communication: Less obvious to humans (except in a few cases) is olfactory communication. Many mammals, in particular, have glands that generate distinctive and long-lasting smells, and have corresponding behaviours that leave these smells in places where they have been. Often the scented substance is introduced into urine or feces. Sometimes it is distributed through sweat, though this does not leave a semi-permanent mark as scents deposited on the ground do. Some animals have glands on their bodies whose sole function appears to be to deposit scent marks: for example Mongolian gerbils have a scent gland on their stomachs, and a characteristic ventral rubbing action that deposits scent from it. Golden hamsters and cats have scent glands on their flanks, and deposit scent by rubbing their sides against objects; cats also have scent glands on their foreheads. Bees carry with them a pouch of material from the hive which they release as they reenter, the smell of which indicates that they are a part of the hive and grants their safe entry. Ants use pheromones to create scent trails to food as well as for alarm calls, mate attraction and to distinguish between colonies. Additionally, they have pheromones that are used to confuse an enemy and manipulate them into fighting with each other.[10]
* Bioluminescence, common in the oceans deeps and with fireflies.
* Electrocommunication: A rarer form of animal communication is electrocommunication. It is seen primarily in aquatic life, though some mammals, notably the platypus and echidnas are capable of electroreception and thus theoretically of electrocommunication.[1Functions of communication
While there are as many kinds of communication as there are kinds of social behaviour, a number of functions have been studied in particular detail. They include:
* agonistic interaction: everything to do with contests and aggression between individuals. Many species have distinctive threat displays that are made during competition over food, mates or territory; much bird song functions in this way. Often there is a matched submission display, which the threatened individual will make if it is acknowledging the social dominance of the threatener; this has the effect of terminating the aggressive episode and allowing the dominant animal unrestricted access to the resource in dispute. Some species also have affiliative displays which are made to indicate that a dominant animal accepts the presence of another.
* Mating rituals: signals made by members of one sex to attract or maintain the attention of potential mate, or to cement a pair bond. These frequently involve the display of body parts, body postures (gazelles assume characteristic poses as a signal to initiate mating), or the emission of scents or calls, that are unique to the species, thus allowing the individuals to avoid mating with members of another species which would be infertile. Animals that form lasting pair bonds often have symmetrical displays that they make to each other: famous examples are the mutual presentation of reeds by Great Crested Grebes, studied by Julian Huxley, the triumph displays shown by many species of geese and penguins on their nest sites and the spectacular courtship displays by birds of paradise and manakins.
* ownership/territorial: signals used to claim or defend a territory, food, or a mate.
* Food-related signals: many animals make "food calls" that attract a mate, or offspring, or members of a social group generally to a food source. When parents are feeding offspring, the offspring often have begging responses (particularly when there are many offspring in a clutch or litter - this is well known in altricial songbirds, for example). Perhaps the most elaborate food-related signal is the dance language of honeybees studied by Karl von Frisch. Young ravens signal to older, more experienced ravens when they come across new or untested food.
* Alarm calls: signals made in the presence of a threat from a predator, allowing all members of a social group (and often members of other species) to run for cover, become immobile, or gather into a group to reduce the risk of attack.
* Meta-communications: signals that modify the meaning of subsequent signals. The best known example is the play face in dogs,[citation needed] which signals that a subsequent aggressive signal is part of a play fight rather than a serious aggressive episode.
Animal communication, and the understanding of the animal world in general, is a rapidly growing field. Even in the 21st century, many prior understandings related to diverse fields such as personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, have been revolutionized. * Gestures: The best known form of communication involves the display of distinctive body parts, or distinctive bodily movements; often these occur in combination, so a distinctive movement acts to reveal or emphasize a distinctive body part. For example, the presentation of a parent Herring Gull’s bill to its chick signals feeding time. Like many gulls, the Herring Gull has a brightly coloured bill, yellow with a red spot on the lower mandible near the tip. When it returns to the nest with food, the parent stands over its chick and taps the bill on the ground in front of it; this elicits a begging response from a hungry chick (pecking at the red spot), which stimulates the parent to regurgitate food in front of it. The complete signal therefore involves a distinctive morphological feature (body part), the red-spotted bill, and a distinctive movement (tapping towards the ground) which makes the red spot highly visible to the chick. Congruently, some cephalopods, such as the octopus, have specialized skin cells that can change the apparent colour, opacity, and reflectiveness of their skin.[1] In addition to being used for camouflage, rapid changes in skin colour are used while hunting and in courtship rituals.[2] While all primates use some form of gesture,[3] Frans de Waal came to the conclusion that apes and humans are unique in that only they are able use intentional gestures to communicate. He tested the hypothesis of gesture evolving into language by studying the gestures of bonobos and chimps.
* Facial expression: Facial gestures play an important role in animal communication. Dogs for example express anger through a snarling and showing their teeth. In alarm their ears will perk up. When fearful a dog will pull back their ears, expose teeth slightly and squint eyes. Jeffrey Mogil studied the facial expressions of mice during increments of increasing pain. What they found were five recognizable facial expressions; orbital tightening, nose and cheek bulge, and changes in ear and whisker carriage.[4]
* Gaze following: Coordination among social animals is facilitated by monitoring of each others' head and eye orientation. Long recognized in human developmental studies as an important component of communication, there has recently begun to be much more attention on the abilities of animals to follow the gaze of those they interact with, whether members of their own species or humans. Studies have been conducted on apes, monkeys, dogs, birds, and tortoises, and have focused on two different tasks: "follow[ing] another’s gaze into distant space" and "follow[ing] another’s gaze geometrically around a visual barrier e.g. by repositioning themselves to follow a gaze cue when faced with a barrier blocking their view". The first ability has been found among a broad range of animals, while the second has been demonstrated only for apes, dogs (and wolves), and corvids (ravens), and attempts to demonstrate this "geometric gaze following" in marmosets and ibis gave negative results. Researchers do not yet have a clear picture of the cognitive basis of gaze following abilities, but developmental evidence indicates that "simple" gaze following and "geometric" gaze following are likely to rely on distinct cognitive foundations.[5]
* Vocalization: Many animals communicate through vocalizations. Communication through vocalization is essential for many tasks including mating rituals, warning calls, conveying location of food sources, and social learning. Male mating calls are used to signal the female and to beat competitors in species such as hammer-headed bats, red deers, humpback whales and elephant seals.[6] In whale species Whale song has been found to have different dialects based on location.[7] Other instances of communication include the warning cries of the Campbell monkey,[8] the territorial calls of gibbons, the use of frequency in Greater Spear-nosed Bats to distinguish between groups.[9]
* Olfactory communication: Less obvious to humans (except in a few cases) is olfactory communication. Many mammals, in particular, have glands that generate distinctive and long-lasting smells, and have corresponding behaviours that leave these smells in places where they have been. Often the scented substance is introduced into urine or feces. Sometimes it is distributed through sweat, though this does not leave a semi-permanent mark as scents deposited on the ground do. Some animals have glands on their bodies whose sole function appears to be to deposit scent marks: for example Mongolian gerbils have a scent gland on their stomachs, and a characteristic ventral rubbing action that deposits scent from it. Golden hamsters and cats have scent glands on their flanks, and deposit scent by rubbing their sides against objects; cats also have scent glands on their foreheads. Bees carry with them a pouch of material from the hive which they release as they reenter, the smell of which indicates that they are a part of the hive and grants their safe entry. Ants use pheromones to create scent trails to food as well as for alarm calls, mate attraction and to distinguish between colonies. Additionally, they have pheromones that are used to confuse an enemy and manipulate them into fighting with each other.[10]
* Bioluminescence, common in the oceans deeps and with fireflies.
* Electrocommunication: A rarer form of animal communication is electrocommunication. It is seen primarily in aquatic life, though some mammals, notably the platypus and echidnas are capable of electroreception and thus theoretically of electrocommunication.[1Functions of communication
While there are as many kinds of communication as there are kinds of social behaviour, a number of functions have been studied in particular detail. They include:
* agonistic interaction: everything to do with contests and aggression between individuals. Many species have distinctive threat displays that are made during competition over food, mates or territory; much bird song functions in this way. Often there is a matched submission display, which the threatened individual will make if it is acknowledging the social dominance of the threatener; this has the effect of terminating the aggressive episode and allowing the dominant animal unrestricted access to the resource in dispute. Some species also have affiliative displays which are made to indicate that a dominant animal accepts the presence of another.
* Mating rituals: signals made by members of one sex to attract or maintain the attention of potential mate, or to cement a pair bond. These frequently involve the display of body parts, body postures (gazelles assume characteristic poses as a signal to initiate mating), or the emission of scents or calls, that are unique to the species, thus allowing the individuals to avoid mating with members of another species which would be infertile. Animals that form lasting pair bonds often have symmetrical displays that they make to each other: famous examples are the mutual presentation of reeds by Great Crested Grebes, studied by Julian Huxley, the triumph displays shown by many species of geese and penguins on their nest sites and the spectacular courtship displays by birds of paradise and manakins.
* ownership/territorial: signals used to claim or defend a territory, food, or a mate.
* Food-related signals: many animals make "food calls" that attract a mate, or offspring, or members of a social group generally to a food source. When parents are feeding offspring, the offspring often have begging responses (particularly when there are many offspring in a clutch or litter - this is well known in altricial songbirds, for example). Perhaps the most elaborate food-related signal is the dance language of honeybees studied by Karl von Frisch. Young ravens signal to older, more experienced ravens when they come across new or untested food.
* Alarm calls: signals made in the presence of a threat from a predator, allowing all members of a social group (and often members of other species) to run for cover, become immobile, or gather into a group to reduce the risk of attack.
* Meta-communications: signals that modify the meaning of subsequent signals. The best known example is the play face in dogs,[citation needed] which signals that a subsequent aggressive signal is part of a play fight rather than a serious aggressive episode.