Animal
communication is any behaviour 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 (distinguishable from anthroposemiotics,
the study of human communication) has played an important part in the
development of ethology,
sociobiology,
and the study of animal cognition.
Animal
communication, and indeed the understanding of the animal world in general, is
a rapidly growing field, and even in the 21st century so far, 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.
Forms of communication
The best known
forms of communication involve the display of distinctive body parts, or
distinctive bodily movements; often these occur in combination, so a
distinctive movement acts to reveal or emphasise a distinctive body part. An example
that was important in the history of ethology was the parent Herring Gull's
presentation of its bill to a chick in the nest. 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. Investigations by Niko Tinbergen
and his colleagues showed that the red colour of the bill, and its high
contrast, are crucial for eliciting the appropriate response from the chick (It
is unresolved whether this actually is an inborn behavior in all its
complexity, or simply a combination of generalized curiosity on part of the
chick, and generalized parental/feeding instincts acting together to produce a
simple learning process via reward. Gull chicks peck at everything that is
brightly colored, mainly red, yellow, white or shining, high-contrast objects,
but the parent's bill is the only such object that will constantly yield food
as a reward when pecked at. Accidental swallowing of pieces of brightly colored
plastic or glass is a common cause of mortality amongst gull chicks).
Another important
form of communication is bird song, usually performed mainly by males, though in some
species the sexes sing in alternation (this is called duetting and serves mainly purposes of strengthening
pair-bonding and repelling competitors). Bird song is just the best known case
of vocal communication; other instances include the warning cries of many monkeys, the
territorial calls of gibbons, and the mating calls of many species of frog.
Less obvious
(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 if they are a part of the hive and grants their
safe entry.
Most of these forms
of communication can also be used for interspecific communication.
Functions
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.
- courtship 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 weed 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.
- 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.
- 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.
- metacommunications: signals that modify the meaning of subsequent
signals. The best known 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 communication
It is important to
note that whilst many gestures and actions have common, stereotypical
meanings, researchers regularly seem to find that animal communication is often
more complex and subtle than previously believed, and that the same gesture may
have multiple distinct meanings depending on context and other behaviors. So
generalizations such as "X means Y" are often, but not always
accurate. For example, even a simple domestic dog's tail wag may be used
in subtlely different ways to convey many meanings including:
- Excitement
- Anticipation
- Playfulness
- Contentment/enjoyment
- Relaxation or anxiety
- Questioning another animal or a human as to intentions
- Tentative role assessment on meeting another animal
- Reassurance ("I'm hoping to be friendly, are you?")
- Brief acknowledgement ("I hear you", or "I'm aware and
responsive if you want my attention")
- Statement of interest ("I want that [food, toy, activity], if
you're willing")
- Uncertainty/apprehension
- Submissive placation (if worried by a more dominant animal)
Combined with other
body language, in a specific context, many gestures such as yawns, direction of
vision, and so on all convey meaning. Thus statements that a particular action
"means" something should always be interpreted to mean "often
means" something. As with human beings, who may smile or hug or stand a
particular way for multiple reasons, many animals reuse gestures too.
Intraspecies vs. interspecies communication
The sender and
receiver of a communication may be of the same species
or of different species. The majority of animal communication is intraspecific
(between two or more individuals of the same species). However, there are some
important instances of interspecific communication. Also, the possibility of
interspecific communication, and the form it takes, is an important test of
some theoretical models of animal communication.
Intraspecies communication
The majority of
animal communication occurs within a single 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
intra-species communication.
Interspecies communication
Many examples of
communication take place between members of different species.
Prey
to predator
If a prey animal
moves or makes a noise in such a way that a predator can detect and capture it,
that fits the definition of "communication" given above. Nonetheless,
we do not feel comfortable talking about it as communication. Our discomfort
suggests that we should modify the definition of communication in some way,
either by saying that communication should generally be to the adaptive
advantage of the communicator, or by saying that it involves something more
than the inevitable consequence of the animal going about its ordinary life.
There are however
some actions of prey species that are clearly communications to actual or
potential predators. A good example is warning colouration: species such as wasps that are capable of
harming potential predators are often brightly coloured, and this modifies the
behaviour of the predator, who either instinctively or as the result of
experience will avoid attacking such an animal. Some forms of mimicry
fall in the same category: for example hoverflies
are coloured in the same way as wasps, and although they are unable to sting,
the strong avoidance of wasps by predators gives the hoverfly some protection.
There are also behavioral changes that act in a similar way to warning
colouration. For example, canines such as wolves and coyotes may adopt
an aggressive posture, such as growling with their teeth bared, to indicate
they will fight if necessary, and rattlesnakes
use their well-known rattle to warn potential predators of their poisonous
bite. Sometimes, a behavioral change and warning colouration will be combined,
as in certain species of amphibians which have a brightly coloured belly, but on which
the rest of their body is coloured to blend in with their surroundings. When
confronted with a potential threat, they show their belly, indicating that they
are poisonous in some way.
A more
controversial example of prey to predator communication is stotting, a highly
noticeable form of running shown by some antelopes
such as Thomson's gazelle in the presence of a
predator; it has been argued that this demonstrates to the predator that the
particular prey individual is fit and healthy and therefore not worth pursuing.
Predator
to prey
Some predators
communicate to prey in ways that change their behaviour and make them easier to
catch, in effect deceiving them.A well-known example is the angler fish,
which has a fleshy growth protruding from its forehead and dangling in front of
its jaws; smaller fish try to take the lure, and in so doing are perfectly
placed for the angler fish to eat them.
Symbiotic
species
Interspecies
communication also occurs in various kinds of mutualism
and symbiosis.
For example, in the cleaner fish/grouper
system, groupers signal their availability for cleaning by adopting a
particular posture at a cleaning station.
Human/ animal communication
Various ways in
which humans interpret the behaviour of domestic animals, or give commands to
them, fit the definition of interspecific 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.
Other aspects of animal communication
Evolution
of communication
The importance of
communication is clear from the fact that animals have evolved elaborate body
parts to facilitate it. They include some of the most striking structures in
the animal kingdom, such as the peacock's tail. Birdsong appears to have brain structures entirely devoted to
its production. But even the red spot on a herring gull's
bill, and the modest but characteristic bowing behaviour that displays it,
require evolutionary explanation.
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. For example, Desmond Morris
showed in a study of grass finches[citation needed] that a beak-wiping
response occurred in a range of species, serving a preening
function, but that in some species this had been elaborated into a courtship
signal.
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. Sociobiologists
argued that behaviours that benefited a whole group of animals might emerge as
a result of selection pressures acting solely on the individual. A gene-centered view of evolution proposes
that behaviors that enabled a gene
to become wider established within a population would become positively
selected for, even if their effect on individuals or the species as a whole was
detrimental.[1]
In the case of communication, an important discussion by John Krebs
and Richard Dawkins established 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
realisation 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 signalling 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.
A recently
published paper[2]
demonstrated that bottlenose dolphins can recognize identity information from
whistles even when otherwise stripped of the characteristics of the whistle;
making dolphins the only animals other than humans that have been shown to
transmit identity information independent of the caller’s voice or location.
The paper concludes that:
“ The fact that
signature whistle shape carries identity information independent from voice
features presents the possibility to use these whistles as referential signals,
either addressing individuals or referring to them, similar to the use of names
in humans. Given the cognitive abilities of bottlenose dolphins, their vocal
learning and copying skills, and their fission–fusion social structure, this
possibility is an intriguing one that demands further investigation.”
V. M. Janik, et al. [2]
Animal communication and human behaviour
Another
controversial issue is the extent to which humans have behaviours that 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 Iraneaus
Eibl-Eibesfeldt have argued that facial gestures such as smiling,
grimacing, and the eye-brow flash on greeting are universal human communicative
signals that can be related to corresponding signals in other primates.
Given the recency with which spoken language has emerged, it is likely that
human body language
does include some more or less involuntary responses that have a similar origin
to the communication we see in other animals.
Humans also often
seek to mimic animals' communicative signals in order to interact with the
animals. For example, cats have a mild affiliative response involving closing
their eyes; humans often close their eyes 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.
Animal communication and linguistics
For linguistics,
the interest of animal communication systems lies in their similarities to and
differences from human language:
1.
Human languages are
characterized for having a double articulation (in the characterization of
French linguist André Martinet). It means that complex
linguistic expressions can be broken down in meaningful elements (such as morphemes
and words),
which in turn are composed of smallest phonetic elements that affect meaning,
called phonemes.
Animal signals, however, do not exhibit this dual structure.
2.
In general, animal
utterances are responses to external stimuli, and do not refer to matters
removed in time and space. Matters of relevance at a distance, such as distant
food sources, tend to be indicated to other individuals by body language
instead, for example wolf
activity before a hunt, or the information conveyed in honeybee dance language. It is therefore
unclear to what extent utterances are automatic responses and to what extent
deliberate intent plays a part.
3.
Human language is
largely learned culturally, while animal communication systems
are known largely by instinct.
4.
In contrast to
human language, animal communication systems are usually not able to express
conceptual generalizations. (Cetaceans and some primates
may be notable exceptions).
5.
Human languages combine
elements to produce new messages (a property known as creativity). One factor
in this is that much human language growth is based upon conceptual ideas and
hypothetical structures, both being far greater capabilities in humans than
animals. This appears far less common in animal communication systems, although
current research into animal culture is still an ongoing process with
many new discoveries.
A recent and
interesting area of development is the discovery that the use of syntax in
language, and the ability to produce "sentences", is not limited to humans
either. The first good evidence of syntax in non-humans, reported[3]
in 2006, is from the putty-nosed monkey (Cercopithecus Nictitans) of
Nigeria.
This is the first evidence that some animals can take discrete units of
communication, and build them up into a sequence which then carries a different
meaning from the individual "words":
The putty-nosed monkeys have two main alarm sounds. A
sound known onomatopoeiacally as the 'pyow' warns against a lurking leopard,
and a coughing sound that scientists call a 'hack' is used when an eagle is hovering nearby.
"Observationally and experimentally we have
demonstrated that this sequence [of up to three 'pyows' followed by up to four
'hacks'] serves to elicit group movement... the 'pyow-hack' sequence means
something like "let's go!" [a command telling others to move]... The
implications are that primates at least may be able to ignore the usual
relationship between an individual alarm call, and the meaning it might convey
under certain circumstances... To our knowledge this is the first good evidence
of a syntax-like natural communication system in a non-human species."
- Animal behavior
- Zoosemiotics: animal
communication on the web
- The Animal
Communication Project
- International
Bioacoustics Council research on animal language.
- Animal Sounds
different animal sounds to listen and download.
Retrieved
from "http://en.wikipedia.org/wiki/Animal_communication"
Whilst different
sections of humanity have had very different views on animal emotion, the
examination of animals with a scientific, rather than anthropomorphic
eye, has led to very cautious steps towards any form of recognition beyond the
capacity for pain and fear, and such demonstrations as are needed and
engendered, for survival. Historically, prior to the rise of sciences such as ethology,
interpretation of animal behavior tended to favor a kind of minimalism known as
behaviorism,
in this context the refusal to ascribe to an animal a capability beyond the
least demanding that would explain a behavior. Put crudely, the behaviorist
argument is, why should humans postulate consciousness and all its near-human
implications in animals to explain some behavior, if mere stimulus-response
is a sufficient explanation to produce the same effects?
The cautious
wording of Beth Dixon's 2001 paper on animal emotion[1]
exemplifies this viewpoint.
"Recent work in the area of ethics and animals
suggests that it is philosophically legitimate to ascribe emotions to nonhuman
animals. Furthermore, it is sometimes argued that emotionality is a morally
relevant psychological state shared by humans and nonhumans. What is missing
from the philosophical literature that makes reference to emotions in nonhuman
animals is an attempt to clarify and defend some particular account of the
nature of emotion, and the role that emotions play in a characterization of
human nature. I argue in this paper that some analyses of emotion are more
credible than others. Because this is so, the thesis that humans and nonhumans
share emotions may well be a more difficult case to make than has been
recognized thus far."
In a similar tone,
according to Jeffrey Moussaieff Masson:
"While the study of emotion is a respectable field,
those who work in it are usually academic psychologists who confine their
studies to human emotions. The standard reference work, The Oxford Companion to
Animal Behavior, advises animal behaviorists that 'One is well advised to study
the behaviour, rather than attempting to get at any underlying emotion'."
There is
considerable uncertainty and difficulty related to the interpretation
and ambiguity
of emotion: an animal may make certain movements and sounds, and show certain
brain and chemical signals when its body is damaged in a particular way. But
does this mean an animal feels - is aware
of - pain as we are, or does it merely mean it is programmed to act a certain
way with certain stimuli? Similar questions can be asked of any activity an
animal (including a human) might undertake, in principle. Though it is well
accepted by scientists that animals do in fact feel pain, that animals have
emotions as we understand them is not a view generally held by most scientists.
Instead instinct
is seen as the driving force behind most animals, though primates are accepted
as more sentient than other animals by many scientists. Such philosophical
questions as emotion implies are difficult to address with reductionist
methods, compared to the relatively exciting and verifiable advances being made
elsewhere in neuroscience at the time. Because of the philosophical
questions of consciousness and mind
involved, many scientists have stayed away from examining animal emotion, and
have studied instead, measurable brain functions, through neuroscience.
For this reason, although many lay people will advocate that animals they know
have emotions, in fact the matter is not considered accepted scientifically.
Current research and findings
Research suggests
that animals can experience negative emotions in a similar manner to people,
including the equivalent of certain chronic and acute psychological conditions.
The classic experiment for this was Martin Seligman's
foundational experiments and theory of learned helplessness at the University of Pennsylvania in 1965, as an
extension of his interest in depression:
A dog that had earlier been repeatedly conditioned to
associate a sound with electric shocks did not try to escape the electric
shocks after the warning was presented, even though all the dog would have had
to do is jump over a low divider within ten seconds, more than enough time to
respond. The dog didn't even try to avoid the "aversive stimulus"; it
had previously "learned" that nothing it did mattered. A follow-up
experiment involved three dogs affixed in harnesses included one that received
shocks of identical intensity and duration to the others, but the lever which
would otherwise have allowed the dog a degree of control was left disconnected
and didn't do anything. The first two dogs quickly recovered from the
experience, but the third dog suffered chronic symptoms of clinical depression as a result of this
perceived helplessness.
A further series of
experiments showed that (similar to humans) under conditions of long term
intense psychological stress, around 1/3 of dogs do not develop learned
helplessness or long term depression. Instead these animals somehow managed to
find a way to handle the unpleasant situation in spite of their past experience.
The corresponding characteristic in humans has been found to correlate highly
with an explanatory style and optimistic
attitude
and lower levels of emotional rigidity regarding expectations, that views the
situation as other than personal, pervasive, or permanent. Such studies
highlighted similar distinctions between people who adapt and those who break
down, under long term psychological pressure, which were conducted in the 1950s
in the realm of brainwashing.
Since this time,
symptoms analogous to clinical depression, neurosis
and other psychological conditions have been in general accepted as being
within the scope of animal emotion as well.
References
1.
^
Ethics & the Environment, Volume 6, Number 2, Autumn 2001, pp. 22-30,
Indiana University Press [1]
2.
^
Jeffrey Moussaieff Masson, Susan McCarthy: When Elephants Weep: The Emotional
Lives of Animals ISBN
0-385-31428-0
See also
- Animal cognition
- Animal communication
- Self awareness
- Thomas Nagel (seminal paper, "What is
it like to be a bat?")
- Emotion
- Neuroethology
- Great Ape personhood
- Pet
- Zoology
- Ethology
- Emotional intelligence
- Affectional bond
Retrieved
from "http://en.wikipedia.org/wiki/Emotion_in_animals"
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