Communication
Animal communication is the transfer of information from one or a group of
animals (sender or senders) to one or more other animals (receiver or receivers)
which affects either the current or future behavior of the receivers. The transfer of
information may be deliberate (e.g. a courtship display) or it may be unintentional
(e.g. a prey animal detecting the scent of a predator).
When animal communication involves multiple
receivers, this may be referred to as an "audience".
The study of animal communication is a rapidly
growing area of study and plays an important part in
the disciplines of animal behavior, sociobiology,
neurobiology and animal cognition. Even in the 21st century, many prior
understandings related to diverse fields such as personal symbolic name use,
animal emotions, learning and animal sexual behavior, long thought to be well
understood, have been revolutionized.
When the information sent from the sender to receiver is either an act or a structure
that manipulates the behavior of the receiver, it is referred to as a "signal".
Signalling theory predicts that for the signal to be maintained in the population, the
receiver should also receive some benefit from the interaction. Both the production
of the signal from the sender and the perception and subsequent response from the
receiver need to coevolve. It is important to study both the sender and receiver of
the interaction, since the maintenance and persistence of the signal is dependent on
the ability to both produce and recognize the signal. In many taxa, signals involve
multiple mechanisms, i.e. multimodal signaling.
Types Of Communication
1.
Visual
For information on the perception of visual signals, see Visual perception.
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 movement acts to reveal or emphasize a body part. A
notable example is the presentation of a parent herring gulls 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.
Facial expression: Facial gestures play an important role in animal
communication. It is a motor expression of one or multiple facial features in
response to some event or a signal of intention for further actions. See
emotion in animals for further information on possible signals of emotion.
Gaze following: Coordination among social animals is facilitated by
monitoring of each other's 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.
Color change: Color change can be separated into morphological color
change, in which changes occur in relation to stage of development, or
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physiological color change, in which color change is triggered by mood,
social context, or abiotic factors such as temperature. Physiological color
change is a versatile mode for communication across a diverse array of taxa.
Bioluminescent communication: Communication by the production of
light occurs commonly in vertebrates and invertebrates in the oceans,
particularly at depths (e.g. angler fish). Two well known forms of land
bioluminescence are fireflies and glow worms.
2.
Auditory
Bird calls can serve as alarms or keep members of a
flock in contact, while the longer and more complex
bird songs are associated with courtship and mating.
Many animals communicate through vocalization.
Vocal communication is essential for many tasks,
including mating rituals, warning calls, conveying
location of food sources, and social learning. In a number of species, males
perform calls during mating rituals as a form of competition against other males
and to signal females, including hammer-headed bats, red deer, humpback whales,
elephant seals, and songbirds. For more information on bird song, see bird
vocalization. In various species, whale vocalizations have been found to have
different dialects based on region.
3.
Olfactory
Despite being the oldest method of communication, chemical communication is
one of the least understood forms due to the noisy nature and sheer abundance of
chemicals in our environment, and the difficulty of detecting and measuring all
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chemical species within a sample. The primary function of chemical reception is to
detect resources (i.e. food) and this function was an adaptive trait (adaptation) first
derived in single-celled organisms (bacteria), living in the oceans, during the early
days of life on Earth.
4.
Electro
A rare form of animal communication is electrocommunication. It is seen primarily
in aquatic animals, though some land mammals, notably the platypus and echidnas
are capable of electroreception and thus theoretically of electrocommunication.
5.
Touch
Touch can be an important factor in social interactions, for example in fights or in a
mating context. In both occasions, the use of touch will increase as an interaction
escalates. In a fight, touch can be used to challenge an opponent, to coordinate
movements during the escalation of the fight, and it can be used by the loser to
perform submissive actions afterwards. Mammals will initiate mating by
grooming, stroking or rubbing against each other. This provides the opportunity to
assess chemical signals of the potential mate, or apply additional chemical signals.
6.
Seismic
Seismic communication is the exchange of information using self-generated
vibrational signals transmitted via a substrate such as the soil, water, spider webs,
plant stems, or a blade of grass among others. This communication holds many
advantages such as being able to be sent regardless of light and noise levels, and
having short ranges and short persistence with little danger of detection by
predators.
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Auto communication
Auto communication is a type of communication system in which the sender and
receiver are the same individual. The sender emits a signal that is altered by the
environment and eventually is received by the same individual. Because the sender
and receiver are the same animal, selection pressure maximizes signal efficacy, i.e.
the degree to which an emitted signal is correctly identified by a receiver despite
propagation distortion and noise. Autocommunication can be divided in two main
systems. The first is active electrolocation found in the electric fish Gymnotiformes
(knifefishes) and
Mormyridae (elephantfish) and also in the
platypus
(Ornithorhynchus anatinus). The second form of autocommunication is
echolocation, found in bats and Odontoceti.
Thermal
The ability to sense infrared thermal radiation evolved independently in various
families of snakes. Essentially, it allows these reptiles to see radiant heat at
wavelengths between 5 and 30 m to a degree of accuracy such that a blind
rattlesnake can target vulnerable body parts of the prey at which it strikes. It was
previously thought that the organs evolved primarily as prey detectors, but it is
now believed that it may also be used in thermoregulatory decision making.
Mechanisms
In spite of its detection of IR light, the pits IR detection mechanism is not similar
to photoreceptors - while photoreceptors detect light via photochemical reactions,
the protein in the pits of snakes is in fact a temperature sensitive ion channel.
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Functions
There are many functions of animal communication. However, some have been
studied in more detail than others. This includes:
Communication during contests: Animal communication plays a vital role
in determining the winner of contest over a resource. Many species have
distinct signals that signal aggression or willingness to attack or signals to
convey retreat during competitions over food, territories, or mates.
Mating rituals: Animals produce signals to attract the attention of a possible
mate or to solidify pair bonds. These signals frequently involve the display
of body parts or postures. For example, a gazelle will assume characteristic
poses to initiate mating.
Ownership/territorial: Signals used to claim or defend a territory, food, or
a mate.
Food-related signals: Many animals make "food calls" to attract a mate,
offspring, or other members of a social group to a food source. Perhaps the
most elaborate food-related signal is the Waggle dance of honeybees studied
by Karl von Frisch. One well known example of begging of offspring in a
clutch or litter is altricial songbirds.
Alarm calls: Alarm calls communicate the threat of a predator. This allows
all members of a social group (and sometimes other species) to respond
accordingly.
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Meta-communication: Signals that will modify the meaning of subsequent
signals. One example is the 'play face' in dogs which signals that a
subsequent aggressive signal is part of a play fight rather than a serious
aggressive episode.
Interpretation of animal behavior
Animal behavior is sometimes very hard to interpret. It is not so hard to describe,
but to give the right meaning to behavior is much harder. Psychological
interpretations of animal behavior are often anthropomorphized, leading to wrong
conclusions. On the other hand, the similarities between human behavior and
certain animal behavior cannot be ignored. Anthropomorphizing behavior is most
often applied to domesticated animals, like cats and dogs, and with apes, because
of the close phylogenetic relationship to humans. An experiment on chimpanzees
shows that a small dose of anthropomorphizing often gives better scientific
results than when researchers try to describe all behavior objectively, but
skepticism remains for this concept.
Examples of tail position indicating different emotions in dogs
"Small dog watching a cat on a table"
"Dog approaching another dog with hostile intentions"
"Dog in a humble and affectionate frame of mind"
"Half-bred shepherd dog"
Combined with other body language, in a specific context, many gestures e.g.
yawns, direction of vision, all convey meaning. Thus statements that a particular
action "means" something, should always be interpreted as "often means". As with
human beings, who may smile or hug or stand a particular way for multiple
reasons, many animals also re-use gestures.
Intraspecific
Much animal communication occurs between members of the species and this is
the context in which it has been most intensively studied. Most of the forms and
functions of communication described above are relevant to intraspecific
communication.
Interspecific
Many examples of communication take place between members of different
species. Animals communicate to other animals with various signs: visual, sound,
echolocation, vibrations, body language, and smell.
Human/animal
Various ways in which humans interpret the behavior of domestic animals, or give
commands to them, are consistent with the definition of interspecies
communication. Depending on the context, they might be considered to be predator
to prey communication, or to reflect forms of commensalism. The recent
experiments on animal language are perhaps the most sophisticated attempt yet to
establish human/animal communication, though their relation to natural animal
communication is uncertain. Lacking in the study of human-animal communication
is a focus on expressive communication from animal to human specifically. Horses
are taught not to communicate (for safety).
Other aspects
Evolution
The importance of communication is evident from the highly elaborate
morphology, behaviour and physiology that some animals have evolved to
facilitate this. These include some of the most striking structures in the animal
kingdom, such as the peacock's tail, the antlers of a stag and the frill of the frill-
necked lizard, but also include even the modest red spot on a European herring
gull's bill.
There are two aspects to the required explanation:
identifying a route by which an animal that lacked the relevant feature or
behaviour could acquire it;
identifying the selective pressure that makes it adaptive for animals to
develop structures that facilitate communication, emit communications, and
respond to them.
Significant contributions to the first of these problems were made by Konrad
Lorenz and other early ethologists. By comparing related species within groups,
they showed that movements and body parts that in the primitive forms had no
communicative function could be "captured" in a context where communication
would be functional for one or both partners, and could evolve into a more
elaborate, specialised form.
The second problem has been more controversial. The early ethologists assumed
that communication occurred for the good of the species as a whole, but this would
require a process of group selection which is believed to be mathematically
impossible in the evolution of sexually reproducing animals.
The apparently excessive eye-spot signalling by the
male peacock tail may be runaway selection
In the case of communication, an important discussion
by John Krebs and Richard Dawkins established
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hypotheses for the evolution of such apparently altruistic or mutualistic
communications as alarm calls and courtship signals to emerge under individual
selection. This led to the realization that communication might not always be
"honest" (indeed, there are some obvious examples where it is not, as in mimicry).
The possibility of evolutionarily stable dishonest communication has been the
subject of much controversy, with Amotz Zahavi in particular arguing that it
cannot exist in the long term. Sociobiologists have also been concerned with the
evolution of apparently excessive signaling structures such as the peacock's tail; it
is widely thought that these can only emerge as a result of sexual selection, which
can create a positive feedback process that leads to the rapid exaggeration of a
characteristic that confers an advantage in a competitive mate-selection situation.
Cognitive aspects
Ethologists
and
sociobiologists
have
characteristically
analysed
animal
communication in terms of more or less automatic responses to stimuli, without
raising the question of whether the animals concerned understand the meaning of
the signals they emit and receive. That is a key question in animal cognition. There
are some signalling systems that seem to demand a more advanced understanding.
A much discussed example is the use of alarm calls by vervet monkeys. Robert
Seyfarth and Dorothy Cheney showed that these animals emit different alarm calls
in the presence of different predators (leopards, eagles, and snakes), and the
monkeys that hear the calls respond appropriately - but that this ability develops
over time, and also takes into account the experience of the individual emitting the
call. Metacommunication, discussed above, also seems to require a more
sophisticated cognitive process.
Animal communication and human behaviour
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Another controversial issue is the extent to which human behaviours resemble
animal communication, or whether all such communication has disappeared as a
result of our linguistic capacity. Some of our bodily features - eyebrows, beards
and moustaches, deep adult male voices, perhaps female breasts - strongly
resemble adaptations to producing signals. Ethologists such as Irenus EiblEibesfeldt have argued that facial gestures such as smiling, grimacing, and the
eyebrow flash on greeting are universal human communicative signals that can be
related to corresponding signals in other primates. Given how recently spoken
language has emerged, it is very likely that human body language does include
some more or less involuntary responses that have a similar origin to the
communication we have
Humans also often seek to mimic animals' communicative signals in order to
interact with them. For example, cats have a mild affiliative response of slowly
closing their eyes; humans often mimic this signal towards a pet cat to establish a
tolerant relationship. Stroking, petting and rubbing pet animals are all actions that
probably work through their natural patterns of interspecific communication.
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2)
Maynard-Smith and Harper, 2003
3)
de Waal
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Range F. and Virnyi, Z. (2011). Development of gaze following abilities in
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Motluk, Alison (2001). "Big Bottom". New Scientist 19 (7).
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"Vocal Development" from Birds of Stanford essays". Retrieved 9 Sep 2008.
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