溝通的演化 (the evolution of communication) ─ 動物行為學 (ethology) 鄭先祐 (ayo)...

溝通的演化 (The Evolution of Communication) ─ 動物行為學 (Ethology)

鄭先祐 (Ayo)

國立臺南大學環境與生態學院生態科學與技術學系教授

Ayo NUTN Web: http://myweb.nutn.edu.tw/~hycheng/

大學部生態學與保育生物學學程 ( 必選 ) 2010 年秋冬

Ayo 教材 (動物行為學 2010) 2

Part 3. 個體間的互動

生殖行為 (Reproductive Behavior) 親代照顧與交配體系 (Parental Care and Mating

Systems) 溝通：管道與功能 (Communication: Channels and

Functions) 溝通的演化 (The Evolution of Communication) 衝突 (Conflict) 團體生活，利他和合作 (Group Living, Altruism,

and Cooperation)


15b 溝通的演化

The changing views of communication Sharing information Manipulating others

Signals and honesty The evolutionary origins of signals

Retualization Receiver-bias mechanisms

Selective forces that shape signals Language and apes

What is language? Ape language studies

Communication and animal cognition ( 認知 )

Communication: Evolution

By Goodenough, McGuire, and Jakob


Views about communication are changing

We can answer the questions of who, what, where, and when of the communication process But it is difficult to answer questions of how and why have

signals taken various forms that they have Communication involves the transmission of information

from one animal to others A cooperative view of communication: both sender and

receiver benefit from the accurate transfer of information Selection should make signals efficient, reliable, and

unambiguous Dishonest or inaccurate signaling was thought to be unlikely


Animals manipulate other animals

The cooperative view of communication does not fit every situation

A sender might gain by sending an inaccurate signal In a territorial dispute, the sender might bluff by sending

signals that exaggerate its willingness to escalate the contest

A male competing for a female’s attention might exaggerate his qualities


Dishonesty may benefit an animal

An animal that gives a dishonest signal gains an advantage Over animals that honestly communicate their abilities or

intentions So, animals don’t communicate to convey information

But to manipulate the behavior of others to their own advantage


Signals: normally reliable, occasionally deceptive

An animal produces a signal when, on average, it increases its own reproductive success By influencing the behavior of others For signals to evolve, they must benefit senders overall

Senders may not be trustworthy If signals are potentially dishonest, why not just

ignore them? On average, the receiver must benefit from responding

to signals Even if it is sometimes deceived


When are honest signals likely?

Four circumstances under which we expect to see honest signals: When senders and receivers share overlapping goals When signals indicate something about the sender that

cannot be faked When signals are costly to produce When dishonest signalers can be identified


Honest signals: senders and receivers share goals Natural selection favors unambiguous, honest signals for

coordination of mating activities The sexes share overlapping goals in the relationship

between parent and offspring But even this relationship can entail significant conflict

Altricial baby bird s( 幼鳥 ) beg their parents to feed them Baby birds stand, gape, flap their wings, and call


Honest communication

Begging chicks are obvious to predators Begging too much, when food is not needed, is a poor

strategy Parents provide food to chicks that beg most vigorously

Parents respond because their own fitness depends on the survival of their offspring Communication between baby birds and parents is honest

Other examples of similar goals of the sender and receiver Belding’s ground squirrels call to warn relatives of a

predator Every bee benefits when scouts convey the location of a

patch flowers


Honest signals: signals cannot be faked

Signals are honest because they are tightly linked to a trait of the sender The sender simply cannot fake the signal

Size is a good predictor of fighting success Displays allow opponents to judge one another’s size

Combatants( 戰鬥人員 ) enhance their apparent size Puffing up their feathers Fluffing out their fur Assuming an upright posture

In other species, size is not so easily faked


Male stalk-eyed flies send honest signals

During an aggressive display, these flies strike a pose that Allows each competitor to compare the length of its

eyestalks Males with shorter eyestalks usually retreat without a

fight


Honest signals are linked to an animal’s health Bright red and yellow feathers, scales, or fleshy necks

or combs of some birds Depend on chemicals called carotenoids Carotenoids must be obtained in the diet

These bright colors honest signal of foraging ability and health Female house finches prefer brighter, redder males

Females benefit from their choice Brighter males are better parents Bringing more food to the nestlings.


Honest signals: are costly to produce

What prevents a male from exaggerating his qualities? Handicap principle ( 障礙原則 ): reliable signals are

favored when signals are costly to the sender Their very extravagance indicates the owner’s qualities

These signals are handicaps Their owners are perceived as doing well In spite of the handicap of investing in the signal


Criteria for a signal to evolve as a handicap The signal must be costly It must relate to the quality of the sender The receiver must be interested in the quality of the

sender that is being signaled And must benefit from attending to an honest signal

Receivers benefit from correctly assessing the quality of a signaler Especially in the context of sexual selection


Signals may be costly

Energetic costs are the most common measurements Oxygen consumption increases in insects and frogs Male red deer lose weight during the rut cost ( 發情代價 )

Other costs: decreased ability to move, escape, or forage Long tail feathers of male birds serve as sexual ornaments And impair their ability to fly

Higher-quality senders can pay the cost of higher-quality signals Brighter colors, vigorous displays Only male red deer in top physical condition can continue

roaring ( 咆嘯 ) to win the vocal duel ( 聲音對抗 )


Honest signaling in the blue-footed booby

Seabirds with brightly colored feet During their courtship ritual, boobies stand facing one

another The male lifts his feet to display them to the female

Males in good condition have bright blue-green feet Unfed males have dull blue feet

Females prefer males with brightly colored feet

藍腳鰹鳥


blue-footed booby ( 藍腳鰹鳥 ) blue penguins : Few penguin

interactions end in fighting because they suffer flesh wounds and sometimes eye loss


Signal costs also affect receivers

In the form of the response of receivers to the signal Little blue penguins have aggressive displays that

differ in Cost (risk of injury) Effectiveness in deterring an opponent Ability to predict an attack

A penguin conveys information about its willingness to sustain injury while performing the display And its willingness to fight


Penguin displays are honest

Because aggressive encounters are potentially costly Attempting to intimidate ( 威嚇 ) an opponent into

retreat could be costly If the rival called the bluff ( 嚇唬 )

Penguin encounters begin with low-risk displays They escalate until one opponent retreats or a fight

occurs One “bidder” decides that the territory is not worth the

risk


Honest signals: dishonest signalers can be identified A stable social unit favors honest communication

Individuals both send and receive signals at different time

The advantages of sending dishonest signals would be reversed When the animal is the receiver So honesty predominates in the population

Members of social units recognize one another And learn whether a particular individual is honest


Vervet monkeys don’t believe dishonest signalers

Members of a social group stop believing an individual that gives unreliable signals

Vervet monkeys have two different calls that warn of another group of monkeys on their territory Monkeys stopped responding and no longer believed a liar


Vervet monkey alarm calls that alert group members of the approach of a neighboring troop are of two types. The “chutter” warns that another group is nearby. The “wrr” is given when another group is spotted in the distance.


Dishonest signals: senders and receivers have different goals Different goals set the stage for deception ( 欺騙 ) A father bird and his chick share the goal of the

chick’s survival But the chick may want more parental investment than

the father would like to give At the cost of his other chicks or his future

reproduction Signals between parents and chicks are essentially

honest But with some attempt by the chick at manipulation

and deceit


Some signals are bluffs ( 嚇唬 )

Honest signals can be corrupted by dishonest bluffs Stomatopods (mantis shrimps) 蝦蛄 ferociously

defend their burrows Stomatopods have two appendages used in prey

capture and territorial defense Combatants may be injured or killed during battles


Stomatopods (mantis shrimps) 蝦蛄


Mantis shrimp ( 蝦蛄 ) signal their readiness to attack

Readiness to attack is signaled by a threat display (meral spread)

A newly molted stomatopod is defenseless But still gives the meral spread display Its opponent is deceived and retreats

A stomatopod can get away with the bluff The receiver would pay dearly ( 付出昂貴代價 ) if it

tested the honesty of the signal The signal is stable because, on average, it is honest


Honest and dishonest signals coexist

The costliness of signals can reinforce honesty When signals are generally honest A low level of deceit is stable and is expected to evolve

Populations are in flux At any time dishonesty may spread

A signal may be perceived by different receivers Some have the same goals as the sender (i.e. prospective

mate) Some have different goals (a competitor)

A mixed signaling strategy, sometimes honest and sometimes deceptive, may be best


The evolutionary origins of signals

Two approaches may explain the evolutionary origins of signals Identifying the behaviors of the senders that form the raw

material for signals Ritualization

Focusing on how signals exploit the receiver’s sensory biases

Ability to detect some information better than others These two evolutionary pathways are not mutually

exclusive


Ritualization

Many signals get their start as part of another behavior Or as a physiological response That takes on a signaling function later

Ritualization: evolution favors modification of the incipient signal It becomes more stereotyped and unmistakable

The three sources of raw material for signals are1. Intention movements

2. Displacement activities

3. Autonomic responses


1. Intention movements

Animals begin behavior patterns with characteristic movements That prepare them for action

It is possible to judge what the animal intends to do A wolf pulls back its lips and bares its teeth before

biting It improves another wolf’s fitness if he correctly

interprets the bared teeth Rather than waiting to get bit


Avian displays originated with intention movements

For flight or walking A bird about to fly crouches, points its beak, raises its

tail, and spreads its wings Components of the takeoff leap have been ritualized

into communicative signals The blue-footed booby incorporates “sky pointing”

into its courtship dance This display originated in flight But changed during ritualization


2. Displacement activities

Irrelevant actions performed in situations in which an animal has conflicting motivations and is thus indecisive ( 無法決斷 )

Faced with an aggressor, an animal may have conflicting motivations To fight and to flee So it may instead preen itself ( 鳥 ) 用喙理 ( 毛 );

Displacement activities are often incomplete actions Courtship is a time of conflicting tendencies

Sexual partners must come together to mate In spite of aggressive tendencies that keep them apart


Displacement activities in male ducks

Mock preening of the courtship displays of male ducks Originated in displacement preening


3. Autonomic responses

The autonomic nervous system ( 自主神經系統 ) regulates many basic body functions Digestion, circulatory activities, heart rate, diameter of the

blood vessels, thermoregulation Displays may have originated from autonomic functions

At times of stress or conflict The naked head or neck skin of turkey, jungle fowl, and

bateleur flush ( 發紅 ) and swell ( 腫脹 )during stress because of vasodilation These changes are now part of signaling during courtship

and aggressive encounters


Evolution of signals from the respiratory system

Modifications of the respiratory system produce sound signals And visual signals

In inflation displays of birds, males fill pouches with air to attract mates The male frigate bird’s throat pouch

inflates to an enormous size and brilliant color to attract females


Evolution of signals from thermoregulation

Piloerection (erection of feathers and hair) traps heat It is also a part of aggressive( 攻擊 ) and appeasement( 緩和 )

displays A zebra finch that cannot escape from a dominant individual

Fluffs its feathers as an appeasement signal Feather position can be part of courtship displays

Tail-raising courtship display of the peacock ( 孔雀 ) In mammals the message’s meaning varies with the part of the

body on which hair is erected If all the hair is erect on tamarins ( 狨猴 ) : attack or be

indecisive If only the tail hair is erected: flee ( 逃走 )


zebra finch tamarins ( 狨猴 )


Other behaviors as raw materials for displays

Ritualization is a highly opportunistic evolutionary process It can be launched from almost any behavior pattern,

anatomical structure or physiological change Predatory behaviors have been ritualized in the male

gray heron ( 灰鷺 ) During courtship, he erects his crest and body feathers Points his head downward and snaps his mandibles

closed Movements are similar to those used during fishing


gray heron ( 灰鷺 )

Masked lovebirds


Food exchange has also been ritualized

The touching of bills is derived from the parental feeding

Is common in courtship and appeasement display Establishes or maintains bonds

Masked lovebirds bill during greetings and after a spat


Flight can also be ritualized

Yellow-headed blackbirds and red-winged blackbirds perform aerial displays to entice( 誘惑 ) females Ritualized flight is more conspicuous than normal flight

Movements are accentuated and reveal plumage patterns

Courtship displays of the fiddler crab evolved from the movement of the male while entering his burrow


Ritualized flight in blackbirds.


The ritualization process

During the evolutionary process of ritualization Signaling behaviors become more stereotyped

They may also change Slow down, speed up, become more exaggerated

Anatomical features (colors, claws) might evolve to draw attention to the display

Emancipation ( 解放 ): behaviors that become freed from the internal and external factors that originally caused them The original triggers no longer cause the behavior to occur The behavior has only a communicative function


Evolution of the whistle-shake in ducks

The body-shake is the evolutionary precursor of the whistle-shake in ducks Serves to dry and rearrange the feathers

Whistle-shakes resemble body shakes But are ended by the duck tilting( 翹起 ) back its head

and emitting a trill ( 顫音 ) And are given in social situations

Some signals are not completely emancipated from their original causes Whistle shakes are still given in response to water

sprays


Receiver-bias mechanisms

Ritualization focuses on characteristics of the sender Sensory exploitation hypothesis: the receiver has a

preexisting preference for a particular signal Features of the receiver’s nervous system makes it more

responsive to a particular form of stimulus The sender takes advantage of the receiver’s preexisting

sensory biases when new signals are evolving. Evolution of swordtails ( 劍尾魚 ) in fish


Sensory bias in frogs

Female túngara frogs prefer males with lower frequency chuck calls

Female túngara frogs benefit from their preference Low-frequency chucks are produced by larger males Resulting in more fertilized eggs


Sensory bias in water mites

Male courtship signals have exploited the females’ sensory adaptations for prey detection Water mite hunts by ambush

When a courting male detects a female he moves his legs These vibrations mimic prey Leading the female to grab him


Sender characteristics shape signals

Anatomical structures form the foundation for producing signals i.e. sensory organs of electric fish

Body form (i.e. size) influences signal design Small species not be visible, so other sensory modalities

are favored for long-distance communication Physical characteristics may evolve that enhance visual

signals (i.e. facial expression, erection of hair) Smaller species give more acrobatic ( 特技的 ) displays In vertebrates it influences vocalizations


Signal evolution does not happen in a vacuum

Many signals are produced by structures that have other functions Body size, hair, beaks, and respiratory tracts are under

selection for other reasons Besides their role in producing signals

For example, beak shape in Darwin’s finches is important in Feeding behavior Song production


Environmental characteristics affect the choice of communication The habitat helps determine which channel of

communication (sound, chemical, visual, etc.) a species uses

Visual signals are not much use in the ocean’s depths So whales rely on sound for long-distance

communication The habitat affects sound transmission

Attenuation (weakening): how far the sound will carry Degradation: how distorted the signal becomes during

transmission


The acoustic adaptation hypothesis

Acoustic properties of bird song are shaped by habitat structure Songs attenuate and degrade differently in different

environments Songs are more attenuated and degraded in dense foliage Lower frequencies become less distorted in dense foliage

In habitats with complex vegetation structure Songs should have low frequencies, narrow bandwidths Whistles and long notes

In open habitat (i.e. grasslands) Songs should have high frequencies and broad bandwidths Trills and short notes


Habitat structures influence bird songs

Great tits have a large geographic distribution Forest dwellers sing songs with a lower pitch

A narrower range of frequencies Fewer notes per phrase than open woodland birds

No differences were found between other species in different habitats But a review of the literature (meta-analysis) shows that Habitat structure weakly influences acoustic properties

of bird songs


Displays vary according to the background

The environment influence transmission of other channels of communication

Visual signals differ in visually “noisy” versus plain environments

Many lizard species rely on visual displays Head bobs, push-ups, back arching, extension of the

dewlap and tail flicks


Lizard displays and background motion

Jacky lizard species that live in trees display faster and flick their tails more When it is windy and the vegetation moves

Senders of signals may change their behavior when the environment changes


Jacky lizard


Habitat changes caused by humans

Human activities alter the environment in which animals communicate And alter selection pressures on signal form

Great tits do well in both urban and rural environments Urban birds sing shorter, faster songs with higher

minimum frequencies Most likely due to competition with the noise of the urban

background


Human-induced environmental changes affect visual signals Visual signals can be impeded ( 阻礙 ) The Baltic Sea has grown turbid (cloudy)

Making it harder for female stickleback fish to see males

Males have to court much more vigorously to get the female’s attention

The honesty of male signals is reduced because males are not as likely to see each other


Receiver characteristics: sensory drive

Sensory drive: the environment shapes receiver characteristics

Surfperch ( 海鯽 ) are marine fish that live in a variety of habitats Differing in light intensity and variability

The retinas of surfperch species differ They are good at detecting differences in color contrast Or differences in brightness But not both


Different optical habitats of related surfperch species. (left) live in an environment that is highly variable in light intensity.

Striped surfperch (right) live in deeper water in the kelp forest where the background light is more even.

Deepwater surfperch are better at detecting brightness differences Species living in shallow water can better see color differences


Language and apes

Humans are very interested in what separates us from other species Tool use was thought to be confined to humans But this is not the case

Language seems to clearly be a talent confined to humans Which elements of language are unique to humans Which are more broadly shared? Are differences a matter of kind or degree?


True language has four elements

1. Words or signs must be used as true symbols That stand for, or take the place of, a real object, event,

person, action, or relationship

2. Symbols should permit reference to objects or events That are not present

3. There should be some elements of grammar (rules) That determine the relationship between words Changing the order of symbols alters the meaning of the

message

4. Words or signs should be combined to form novel phrases Or sentences that are understandable to others


Early studies taught chimps to talk

Researchers have studied the ability of great apes (chimpanzees, western (lowland) gorillas orangutans, bonobos) to learn language

A chimp named Viki was taught to say three words “Mama,” “papa,” and “cup”

These attempts failed Chimpanzees lack the vocal apparatus to make the

range of sounds of human speech


Studies taught chimps nonverbal languages

Washoe, a young chimpanzee, was taught American Sign Language (ASL)

Washoe and other chimps were reared like human children Spoken English was not allowed Washoe had a vocabulary of 132 signs

Her signs were not restricted to requests She applied them correctly to a wide variety of referents She extended the sign for dog from a picture to all pictures

of dogs, living dogs, and even the barking of an unseen dog


Washoe signs with ASL

Washoe combines signs to denote “water bird” for a swan


Stop and think:

Do you agree that the best way to test whether apes have linguistic skills is to incorporate them into human society as much as possible?

What are the advantages and disadvantages of this approach?


Koko, Chantek and Nim Chimpsky

A gorilla named Koko and an orangutan named Chantek were taught ASL Spoken English was permitted Emphasized the production of language (the use of signs) Not comprehension (understanding the meaning of signs)

Nim Chimpsky a young male chimp, was accused of imitating his trainers But Nim’s language abilities were stunted( 受礙 ) by the

operant-conditioning procedures used in his training And Nim’s trainers changed so often that he could not form

the relationships essential for language development


It was accepted that chimpanzees could not learn language

But when other trainers worked with Nim His language skills improved

Chantek’s signs were more spontaneous Could not be attributed to imitation

Washoe and the other language-trained chimps Signed to other animals and objects And frequently to themselves

Washoe adopted a ten-month-old infant named Loulis Loulis learned his first 55 signs by observing other chimps Washoe and her family signed to one another their daily

activities (playing, eating, family fights)


Sarah used plastic chips as words

The chimpanzee Sarah used a particular plastic chip as a word To complete a preformed statement She arranged four to five words into a

sentence Sarah named many objects and used

complicated relationships Such as if-then and same-different


The LANA Project

A chimpanzee named Lana was trained to use a computer to communicate Eliminating social cueing and the difficulty of

interpreting symbols Lana communicated in Yerkish, a symbolic language

Yerkish words (lexigrams) are geometric figures Pressing a computer key labeled with the lexigram

selects words


The LANA Project

Lexigrams had to be used in an appropriate order Lana had to learn syntax -

rules governing word order She developed a large

vocabulary and mastered grammar

She also coined new words She called an orange soda a

“Coke-which-is-orange”


Apes learn words in various forms

To refer to objects not present Stringing words together in short sequences Follow rules of grammar They coin new words But do apes use words as symbols?

When a chimp uses a “word” (sign, plastic chip, or lexigram) to name an object

Is it used as a symbol that stands for the object Or is it a label that is associated with the object through

a reward system?


Using “words” as true symbols

Two chimpanzees, Sherman and Austin communicated with each other symbolically By pressing computer keys with lexigrams

The emphasis was on interanimal communication, They were not taught to produce strings of lexigrams Or to adhere to grammatical rules


Chimps communicate with each other

Sherman and Austin specify foods to one another using lexigrams They communicate with each other Regardless of which of them is the observer


Chimps use symbols in communication

To inform each other of the appropriate tool to use to solve a problem Clearly using words as symbols and not simply labeling

objects This shifted the emphasis from demonstrating that apes

can produce language To showing that they can understand symbols or words

of language It also showed how important the learning environment

is in developing language comprehension


Kanzi and Panbanisha

Bonobo (pygmy) chimpanzees Kanzi was adopted and raised by Matata

And was always present during Matata’s training sessions

After Kanzi was separated from Matata He used symbols on the keyboard that they had tried to

teach to Matata Not only did he know the lexigrams

He also knew the English words that the lexigrams represented


Kanzi has a large vocabulary

Kanzi learned communication skills by observing his mother’s training Much the same way as a child would

Panbanisha, Kanzi’s half-sister Was reared in the same learning environment as Kanzi She, too, shows remarkable comprehension of spoken

English Reward-based language training was stopped and

replaced with conversation Kanzi’s human companions served as communicative

models


Kanzi learned symbols through observation

Kanzi communicates using a board with 256 lexigrams

• Kanzi observed and interacted with humans who used gestures and lexigrams to communicate


Kanzi and others understand spoken English Besides being able to produce language Kanzi was not trained to vocalize

But spontaneously makes sounds with different content Chimpanzees utter natural sounds when they find food

Producing distinct grunts when encountering different foods

This skill is found in other animals besides apes Including vervet monkeys and even chickens

Ape communication fulfills the four requirements of language


Communication and animal cognition

Do nonhuman animals have thoughts or subjective feelings? Are they are aware of other animals’ feelings? Are they cognitive, conscious, aware beings?

Tapping animals’ communication lines can indicate whether animals have conscious thoughts or feelings If nonhuman animals thoughts and feelings They probably communicate them to others through

their communication signals


Evidence of cognition: forming mental representations Of objects or events that are out of sight Some animal signals are symbolic

They refer to things that are not present Some animals learn a language that uses symbols

i.e. apes


Other species understand symbols

Alex the parrot could vocally request more than 80 items Even if they were out of sight He could quantify and categorize these objects He understood the concepts of color, shape, and same versus

different for both familiar and novel objects Bottlenosed dolphins also understand symbolic languages

“Words” are gestures or are generated by a computer They can refer to objects, actions, and relationships Dolphins understand experimenter’s references to objects that

are not present


Evidence of cognition( 認知 ): natural communication systems

Language involves the ability to relate words to meanings

In some species, individuals classify signals by their meaning Not by some obvious physical property (the way a signal

sounds) When a rhesus monkey finds food

It announces this with one or more of five different food calls

A different type of call announces if the item is of high quality or rare


Classifying calls by meaning or sound

Animals habituate (gradually stop responding) to a stimulus that is repeated many times without consequence

If monkeys classify a food call by its sound After habituating to one type of call they still respond to

any other type of call because it sounds different If they classify a food call by its meaning

They will be unresponsive to a call in the same category But remain responsive to a call in a different category

Rhesus monkeys classify calls by their meaning.


Evidence of cognition: understanding mental states of others

Does a communicating animal understand what potential receivers know? Vervet monkeys apparently do not

Mother vervet monkeys give alarm calls when they sense a predator But do not take into account whether their offspring

are ignorant or knowledgeable about the predator


Langurs call to their audience

Male Thomas langurs give alarm calls But only if there is an audience

Males call persistently after spotting a predator Stopping only when every other member in the group

also gave an alarm call Callers seem to keep track of all the other members in

their groups


Ethical ramifications of cognition in animals

The question of animal awareness is difficult to answer scientifically

The answer has ethical ramifications If the line between animals and humans is erased or even

smudged a bit, should we rethink the way we treat animals? Should we keep them in zoos? Should great apes be used for language studies? What about dolphins?

So what’s your opinion? Are animals aware, cognitive beings? All of them? Where do we draw the line?


Summary

Signals should be honest, unambiguous and informative Sometimes the sender of a signal benefits from being dishonest

On average, a sender manipulates the behavior of others to its own advantage

Receivers should respond to signals when they benefit from them, on average, even if they are sometimes deceived

Conditions for honest signals (1) senders and receivers share overlapping goals, (2) they cannot be faked, (3) they are costly to produce, and (4) dishonest signalers can be identified

Conditions that favor dishonest signals (1) senders and receivers have different goals, (2) they are costly to assess or to challenge


Summary

Honest and dishonest signals can coexist in a population Signals originate through ritualization and sensory exploitation Evolutionary sources of ritualization (1) intention movements,

(2) displacement activities, and (3) autonomic responses The design of the signal may be influenced by the anatomy and

physiology of the sender and the habitat Most animal communication signals are not true language

They do not use symbols that can replace their referent They do not string signals together to form novel sentences Researchers have attempted to teach apes language

Some animals understand signals that represent unseen items


問題與討論

[email protected]

Ayo 台南 NUTN 站 http://myweb.nutn.edu.tw/~hycheng/

溝通的演化 (the evolution of communication) ─ 動物行為學 (ethology) 鄭先祐 (ayo)...

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