The Evolution of Communication

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The Evolution of Communication

• Marc D. Hauser.

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Introduction

• Nothing would work in the absence of
  communication .- (Hauser)
• Flowers must communicate with bees for
  pollination
• Male songbirds must communicate with females if
  they are to mate and rear young
• Lions on a cooperative hunt must communicate with
  each other about how they will attack their prey
• A human infant must communicate with its parents
  so that the needs of both are met
• Computer programmers must design software to
  communicate their hardware
• Computer networks

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Introduction

• But why do birds sing rather than speak Mandarin?
  Why is this talk conveyed in English and not by
  the blinking of eyes - Morse code style?
• These are questions about design features of the
  communication systems
• The design features of a communication system are
  the result of a complex interaction between the
  constraints of the system (cost) and the demands
  of the job required
• What are the mandatory features?

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Communication Definitions

• Sociobiology Communication occurs when the
  action of or cue given by one organism is
  perceived by and thus alters the probability
  pattern of behavior in another organism in a
  fashion adaptive to either one both of the
  participants
• Ethology Communication is the transfer of
  information via signals sent in a channel between
  a sender and a receiver . The occurrence of
  communication is recognized by a difference in
  the behavior of the reputed receiver in two
  situations that differ only in the presence or
  absence of the reputed signal . . . . the effect
  of a signal may be to prevent a change in the
  receiver's output , or to maintain specific
  internal behavioral state of readiness

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Introduction

• Cognitive psychology Communication is a matter
  of causal influence. . .. the communicator must
  construct an internal representation of the
  external world , and then . . . carry out some
  symbolic behaviour that conveys the content of
  that representation . The recipient must first
  perceive the symbolic behaviour , i . e .
  construct its internal representation and then
  from it recover a further internal representation
  of the state that it signifies . This final step
  depends on access to the arbitrary conventions
  governing the interpretation of the symbolic
  behaviour

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Introduction

• Linguistics Human communication . . . includes
  forms of verbal communication such as speech ,
  written language and sign language . It comprises
  nonverbal modes that do not invoke language
  proper, but that nevertheless constitye extremely
  important aspects of how we communicate . As we
  interact, we make various gestures some vocal
  and audible, others nonvocal like patterns of eye
  contact and movements of the face and the body.
  Whether intentional or not, these behaviors carry
  a great deal of communicative significance

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Introduction

• Organisms differ with regard to what they can
  convey and what they perceive . Consequently ,
  there are a diversity of communication systems
  the natural world.
• Hauser uses 4 perspective to comparatively
  explore the diverse animal communication
  systems
• Mechanistic - Understanding the mechanisms
  (neural , physiological , psychological )
  underlying the expression of a
  traitOntogentic - The genetic and environmental
  factors that guide the development of a
  trait
• Functional - Looking at a trait terms of its
  effects on survival and
  reproduction
• Phylogenetic - Unraveling the evolutionary
  history of the species so that the
  structure the trait can be evaluated in
  light of ancestral features

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Talk Outline

• Introduction
• Approaches to study communication evolution
• Conceptional issues in communication
• Ontogeny
• Adaptive significance

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Ethological Approach
Non Signals Breathing Defensinve
Posture Preflight Movement Urinating

• Early ethologists focused on the evolutionary
  origins of signals.
• The general view was that signals emerged from
  nonsignals
• Once nonsignals gain functionality (influence the
  probability of survival and mating) , they become
  ritualized , emerging as communicative signals
• Once a ritualized signal evolved, its ultimate
  form was designed for maximizing information
  transfer.
• Selection operated on the sender to provide
  recipients with signals conveying unambiguous
  information.
• Rare signals and large repertoires were selected
  against because they would lead to a slowed in
  recipients

Evolution
Ritualized Signals Courtship song Foraging
display Submissive signal Territorial marking
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Ethological Approach (70)

• In contrast to the ambiguity reduction, the
  new view claimed that ritualized signals were
  foils, designed increase ambiguity by concealing
  the signaler 's " true " motivations
• selection should operate against individuals
  using displays that are highly predictive of
  their subsequent behavior ( highly informative)
• In some primates , individuals bristle their hair
  when they are aggressive . This display is to
  make the signaling animal larger. If an
  individual spots another with its hair bristled ,
  it move off in the opposite direction and thus
  avoid the attack
• Once the association between hair bristling and
  retreat is established, an evolutionary option
  becomes available signalers can bypass the more
  costly attacks and simply hair bristle in order
  to cause others to

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Ethological Approach (70)

• But what about cooperative interactions?
• Empirically, one tends to find that during
  competitive interactions over valued resources
  (food, mates ), signals are loud and exaggerated
  , consequently costly to produce
• Krebs Dawkins have suggested that cooperative
  signals should be quiet , subtle , produced with
  minimal cost, and responded to with high
  sensitivity (perceiver s threshold for responding
  should be low )

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Derek Bickerton

• Studied cases of language change that have
  occurred a result of different cultures coming
  together
• When two communities lacking a common language
  are with a situation that requires communication,
  Bickerton suggested the emergence of
  protolanguage, or what is known as pidgin
• Relative to natural languages, the structure of a
  pidgin is quite simple, often consisting of short
  strings and only a few grammatical items .
• Over time, especially with the subsequent
  generation of offspring , we see a refinement in
  the structure and usage of language what is
  known as a creole
• How constrained will be the structure and usage
  of creole?
• Fundamental genetic changes were responsible for
  the emergence of the first protolanguages

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Charles Hockett
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Peter Marler

• Marler's observations of avian vocalizations
  produced in the context of predator led to a
  non-arbitrary acoustic features , maximize either
  silent predator evasion or predator attack
• Birds use structurally different calls when they
  are mobbing a predator (max localization) as
  opposed to when they are warning group about
  presence of a predator (min localization for
  predator)
• Marler suggested that the vervet monkey's alarm
  call system represented a potential case of
  symbolic signaling (not just changes in affective
  state).

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Peter Marler

• Seeing predator or hearing a particular
  acoustically distinctive alarm calls elicited a
  specific escape response , and one that appeared
  to be designed to maximize the probability of
  escape given the predator's hunting strategy
• The definitive test of this hypothesis was
  carried out several years later when Seyfarth
  Cheney, and Marler playback experiments showing
  that the acoustic features of each alarm call
  type were sufficient to elicit the behaviorally
  appropriate response

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Peter Marler

• Also, Marler, pinpointed 7 parallels between
  birdsong and human speech
• 1 . Young learn the species typical repertoire
  from adult models
• 2. Dialects are formed as a result learning.
• 3. Experientially guided learning is most
  significant during a critical period .
• 4. To develop a normal vocal repertoire , young
  must be able to hear sounds from their species
  typical repertoire and to hear themselves
  reproduce such sounds .
• 5. Like human infants , young also go through a
  series of developmental stages , including a
  subsong phase that resembles babbling .
• 6. Vocal imitation, in and of itself may be self
  reinforcing.
• 7. Left hemisphere is dominant for the control of
  sound production (Chomsky combintorial organ)

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Talk Outline

• Introduction
• Approaches to study communication evolution
• Conceptional issues in communication
• Ontogeny
• Adaptive significance

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Ecology of Signal Transmission

• Studies strongly suggest that selection has
  favored signals with particular design features,
  matched to achieve optimum transmission in the
  species-typical environment.
• H . Brown and Waser's (1984, 1988) experimental
  results on nonhuman primates indicate that calls
  that function in intergroup interactions and
  require long distance transmission are produced
  within a spectral range that minimizes
  attenuation
• An individual may have the neurophysiological
  substrate required to discriminate small
  differences in frequency , but because of
  attentional distractors in the environment may
  completely miss the signal conveyed.
• What can be discriminated under ideal conditions
  and what is discriminated and acted upon under
  natural conditions?

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Ecology of Signal Transmission

• A common methodological approach in environmental
  acoustics involves the following three steps
• 1. Record a signal under relatively ideal
  conditions
• or generate a computer synthesized
  signal .
• 2. Play the signal back under different
  ecological
• conditions.
• 3. Record the signal played back and compare the
  
• in acoustic morphology with the originally
• emitted signal (subtract Fourier).

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Signal detection theory

• Signal detection theory studies the cost
  relationship between discriminability and
  attention
• Imagine a gazelle that must avoid prey to a
  predatory cheetah . To avoid being eaten, the
  gazelle evolved an alarm call system.
• signal detection theory generates a series of
  probability curves that reveal the trade off
  false alarms and misses , given the
  signaltonoise ratio in the environment
• Gazelles optimum strategy requires a level of
  vigilance (sampling) that will maximize hits and
  minimize misses (false alarms)

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Similarity and Classification

• To respond to things appropriately , animals must
  identify them as belonging to various categories
  potential mates , potential food items ,
  potential predators, and so on . All sentient
  animals therefore simplify the world's diversity
  by imposing their own categorical distinctions
  upon it.
• For the researcher interested in understanding a
  species communication system , there is the
  daunting task of cataloging representative
  exemplars into what are putatively meaningful
  categories that is , of determining
  characteristic (weighted) features associated
  with particular contexts

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Habituation-Dishabituation Paradigm

• A1, A2 represent acoustic stimuli from the same
  category
• B1 Comes from a different category
• Response assay amount of time looking at speaker
  after playback
• Subjects habituate to repeated presentations of
  A1 but show greater dishabituation to B1 than A2

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Timing

• The timing of displays within a sequence
  represents yet another problem.
• The analytical challenge lies in understanding
  whether the signal delivered represents a
  directed response to a prior signal or the
  initiation of a new bout .
• Studies of the squirrel monkey Symmes , Biben ,
  and Masataka (1993) , indicated that responses to
  " chuck " vocalizations typically (with high
  probability) occur in a O.5second period
  vocalizations occurring outside of this time
  window are more likely to reflect the initiation
  of a new vocal bout

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Timing

• But, does response signals must occur within
  restricted periods of time?
• Consider the following discussion
• "Bert, let's have some chicken for dinner ?
• "That sounds good, " says Ernie . " Let's have
  some mushrooms as well and a salad."
• Bert and Ernie enter the kitchen and begin
  cooking.
• Five minutes later, Bert speaks to Ernie without
  making eye contact
• "I think I will make a vinaigrette dressing to
  go along with salad ."

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Nonhuman Grammer

• For nonhuman animals we don't fully understand
  what the relevant units of communication are,
  and thus we are crippled in our ability to say,
  one way or the other, whether grammatical
  structure underlies their utterances
• In black chickadees and capuchin monkeys,
  different call types within the repertoire are
  strung together in sequences based on ordering (A
  before B and C but never after B or C ). Missing
  from analysis, however, is a clear description of
  meaning or semantics of each call type
• Empirically build Markov sequence analysis

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Talk Outline

• Introduction
• Approaches to study communication evolution
• Conceptional issues in communication
• Ontogeny
• Adaptive significance

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Ontogeny

• Some organisms are born with theessential
  mechanisms for responding appropriately to
  biologically meaningfulstimuli in the
  environment. For others, appropriate responses
  emerge overtime, shaped in part by
  maturationand experience.
• Note that a behavior that emergedwithout
  experience can be modifiedby practice. On the
  other hand, genetic factors determine the
  modeof responsiveness to experience.
• Considering real world organisms , the notion
  of canalization tell us that during the course of
  development, individuals will encounter a variety
  of experiences that have the potential to throw
  them off of their species typical trajectory

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Vervet Monkey Alarm Call

• To determine when vervet monkeys begin to use
  alarm calls in the appropriate context Seyfarth,
  Cheney Hauser(1992) analyzed of naturally
  occurring predator encounters and infants vocal
  responses
• Results indicate that up until the age of two to
  three years , immatures produce alarm calls to
  both predatory and nonpredatory species. With
  increasing age, the number of species eliciting
  alarm calls diminishes to the point where alarms
  are only given in response to predators
• We can interpret the developmental results as
  providing evidence that infents make
  classification "mistakes" , producing alarm
  calls to inappropriate objects.
• Or infants may be using alarm calls to ask
  questions ("Is that thing in the air something I
  should give an eagle alarm call to?")
• when infants produce alarm calls , adults often
  follow with the same type alarm call , if a
  vervet predator detected

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Vervet Monkey Alarm Call

• When infants produce alarm calls , adults often
  follow with the same type alarm call , if a
  vervet predator detected (feedback)
• For correct feedback (equal), infants are more
  likely to produce the correct alarm in the
  subsequent encounter than mistaken infants
  (memory)
• Aggressive actions by mothers toward infants
  producing the inappropriate alarm call -
  punishment!
• Since immature vervets produce alarm calls to the
  same general kinds of stimuli as adults (e.g.
  eagle alarm calls to things in the air), it
  appears that they are born with an innate
  category for context-that-elicit-eagle-sounding-a
  larm-calls

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Talk Outline

• Introduction
• Approaches to study communication evolution
• Conceptional issues in communication
• Ontogeny
• Adaptive significance

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Adaptive significance

• When a squirrel gives an alarm call to a predator
  it does so in order to protect its group. Why?
  given that alarm calling is costly (increases the
  caller's probability of being detected and eaten
  by the predator) what is the benefit ?
• Hamilton (1964) argued that individuals have
  been selected to maximize their inclusive fitness
  refers to the number of genes one passes on to
  generations as a result of direct reproduction
  (the number of offspring you produce who survive
  and reproduce ) and indirect reproduction ( the
  number of individuals you help survive and
  reproduce as a function of your degree of genetic
  relatedness to them)
• But in a population where individuals always
  produce alarm calls against predators, selection
  would favors a mutation that caused an individual
  to withhold the alarm call , run for cover, and
  save its own skin.

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Adaptive significance

• Maynard Smith (1974) applied the logic and
  mathematical tools of economic game theory to
  problems in biology in an attempt to assess
  whether evolutionarily stable strategies ESSs
  existed
• Evidence for an ESS then comes from a set of
  equations and conditions ( specified by the
  details of the matrix ) which indicate that no
  mutational strategy can invade a population X
  of individuals playing strategy 1 and Y playing
  strategy 2

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Zahavi Handicap Principle

• Zahavi (1975 ) argumented that signals are
  honest if and only if they are costly to produce
  and maintain.
• Males with absurdly long tails or shockingly
  bright colors would surely be more vulnerable to
  predation than males with short tails or dull
  colors . Natural selection therefore eliminate
  the showy males and favor the more cryptic ones .
  But individuals who sport the exaggerated traits
  and live tell the tale be truly extraordinary
  males genotypes that can readily tolerate the
  survival costs of the trait
• Are honest signas are more or less likely to
  appear in certain social situations?
• How much cost is either necessary or sufficient
  to both generate and maintain an honest signal?
  (M.Smith 1994)