Chapter 10
The Evolution of Language
Language
• Language is communication, but not all
communication is language
• Currently, unique to humans
Defining Language
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Vocal auditory channel
Arbitrariness: symbols don’t inherently mean anything
Semanticity: language means something
Cultural transmission: cross generational
Spontaneous usage
Turn taking
Duality: language sounds require ordering for sense
Displacement: reference across time/space
Structure dependence: grammar
Creativity: can describe novel events
Components
• Vocabulary
– Specific words with specific meanings
• Grammar
– Rules for sequencing vocabulary
– Allows “limitless” combining of concepts
Questions
• How language evolved
– Gestural
– Vocalization
• Why language evolved
– Dunbar’s social gossip
– Social contract
– Scheherazade effect
Gestural Theory of Language
• Non-human primates
use gestures
• Deaf children learn to
sign readily
• Aimed throwing
– Fine motor control and
speech centres both
localized in (usually)
left brain
• Mirror neurons
– Pre-motor cortex (F5) of
macaques
– Fire when observing
another’s hand movement
and during self-movement
– F5 corresponds to Broca’s
area in humans
Problems
• It’s a big step from gesture to speech
• Gestures not used to convey concepts or ideas
• Brain lateralization does not indicate common
origin
– Different neural circuits
• Recent mirror neuron findings show much more
than motor function
• However, this doesn’t mean that gestural and
vocalization communication couldn’t have evolved
in parallel
Vocalization Theory of Language
• Non-human primates have elaborate
vocalizations
– Prosodic and semantic content
• Semantic content argument
• “Singing” argument
– Synchronizing emotional states
– Contact-calling choruses in non-human primates
Galogos Calls
• Nocturnal, arboreal African primates
• “Bush babies”
• Mouse to cat sized
Thick-tailed Bush Baby
• Calls: attract companions, repel rivals
• Presence of predator
– Knocks...squawks...whistle yaps
• Loudness and pattern give information
– To predator and other bush babies
– Nature of threat
– Distance
• Under attack
– Yell; brings other bush babies to help
• Juveniles separated from mother
– Buzzing call
• 18 calls, each can have up to five meanings
• Calls depend on physical situation
– High pitched calls
• Close quarters, want social contact
– Low calls
• To communicate over distance
Species Differences
• Allen’s galagos
– Dense undergrowth
• Low calls
• Elegant galagos
– Open canopy top
• High calls
Sonograms
• “Vocal fingerprints”
• Can identify different species
– Species and dialect differences
• Combine with physical details
• Dwarf galagos of West Africa
– Not one species, but two
– Thomas’: canopy
– Demidoff’s: undergrowth
• 16 to 40+ species
Human Speech
• Good for information exchange
• Poor at conveying emotional state of
feelings
– Metaphor
– Default to human-style “grooming”
Evolutionarily Selected
Motor projection areas
related to speech
• Language production and
comprehension neurologically
“expensive”
• Costs
– Can’t swallow and breathe at same
time
– Cognitive delay and/or distraction
when speaking
• Benefits necessary to offset costs
– Multitasking, don’t need to
visually attend,
communicating in dark
Broca’s area
Wernicke’s area
Auditory cortex
Learning Language
• Phonemes
– Initially, can detect all phonemes
– With experience focus on those of your own
language(s)
• Ostensive communication
– Associating a sound with an object
– Learning words
– Classification and categorization
Constraints Assisting
Categorization
• Hierarchical elements in language learning
• Whole object assumption
– Word applies to entire object
• Taxonomic assumption
– “Basic level” classification
– Word applies to related class of objects
• Mutual exclusivity assumption
– Non-synonymous meaning of words
Attending to Others
• Learning assisted by attending to speaker of
words
• Joint attention
• E.g., New sound spoken only applies to
object if speaker is attending to it
• E.g., Children eye-track adults to determine
what the new sound applies to
• Innate predispositions assisting language
acquisition
Chomsky’s Universal Grammar
• Learnable argument
– Language learning is too complex to simply be
acquired through behaviorist associations
• Predisposition to grammatical structure
– Innate
– E.g., Children implicitly parse speech into
noun, verb, and object phrases
• Universal Grammar
Universal Grammar
• Different languages have different syntax
and different grammar, but basic abstract
properties common to all
• Person has limited set of parameters
(“grammar switches”) that are activated
through linguistic experience
– Initially, any parameter combination is possible;
experience determines which parameters will
remain active
Universal Grammar and Evolution
• Chomsky argues for innate psychological
mechanisms for learning language
• But, not adaptively selected for linguistic
purpose
• Language “organ” exapted (co-opted) for
current purpose from some earlier purpose
Genetic Basis for Language
• Likely a highly polygenetic condition
– No single “grammar gene”
• Specific Language Impairment (SLI)
– Inflectional morphology problems
• Using language deficits to study genetic
basis
• Some SLI does run in families
– E.g., Some genes on chromosome 7 implicated
Complications
• Hypothesis: regular nouns/verbs stored and a
separately encoded “rule” used to change tense;
irregular words need to be stored individual in
each form
• SLI sufferers may lack ability to apply the rule, so
every word must be stored separately
• Cognitively taxing for storage and recall
• Thus, genes related to SLI may not be
grammatical genes at all…
Non-modular Evolutionary
Account
• Michael Tomasello
• General pattern classifier interpretation
– Species-specific and social cognition and cultural
learning processes involved
• Children learn language by actively attempting to
understand adult communication in context of
attention sharing
• Theory of mind is essential
– Language unique to humans due to humans’ greater
level of identification with conspecifics
Why Did Language Evolve
• Earlier theories tended to focus on issues of
hunting or teaching
• More recent evolutionary theories tend to be
social (e.g., social bonding, courtship,
mating) or social cognitive in their nature
Dunbar’s Social Gossip Theory
• Neocortex size, group size, and language
• Upper limit on group size
– Cognitive constraints
– Personal connections
• Non-human primates
– Social connection via grooming
– On average, about 20% of time budget
– Positive correlation in apes and Old World monkeys
Group Size
• Group size
• ~20% of time
– Limits group to ~50 members
• But, stable groups of ~150 members
• Grooming...43%
• Speaking...~20%
– Converse with up to 3 others at once
Gossip: Benefits Beyond Group
Size
• Relationships between individuals
– Alliances, dominance, hierarchies, altruists,
cheaters, etc.
• What do people talk about?
75%
50%
men
25%
women
social
leisure
culture politics
work
Gossip
• Increase in group size complicates social
living
• Exchange social information
• Policing function in large groups
– Warnings
• Reputation management
– Advertise our own (or allies’) qualities
• Solicit/give behavioural advice
Policing Function
• But, most people don’t talk much about
others’ misdemeanours; mainly discuss
social relationships
• Why?
– Cheating is not a serious problem?
– Don’t like discussing cheating in public?
– Policing is important, but isn’t an everyday
occurrence?
Social Contract Hypothesis
• Mateguarding
– Males away (hunting?); what are women doing?
• Need language to convey information on
emotions, feelings, intentions
– Abstract symbolic form
– Mating fidelity
– Regulation of living arrangements
Issues
• This theory takes pre-existence of large,
socially bonded groups for granted
– But why did the groups evolve initially?
• Non-human species can solve the same
problem without language
• Verbal contracts do not ensure sexual fidelity
• Fidelity probably a problem in EEA
– Language doesn’t seem to fix this
– Expensive courtship rituals, investment,
emotional bonding
Scheherazade Effect
• Language to attract, keep mate (Miller, 2000)
– Entertaining people are the centre of attention
• Verbal skills as demonstration of genotype
– Handicap principle
• Brain as sexually selected organ
• Lekking
– Females better at verbal tests and show faster language
development
– Males have larger vocabulary and are more verbally
flamboyant
Issues
• Miller argues that males are more
artistically prolific than females
– But, many socioeconomic factors could be
responsible
• Unclear if language evolved as a way to
attract a mate, or if this was a subsequent
byproduct
Synthesis
• Language doesn’t fossilize
• No certainty as to when language evolved
• Likely a gradual process from
communication to full, modern language
• Different theories could have held different
value at different ancestral times
• Probably a combination of selective forces
Language and Group
Membership
• Allusions and references
– e.g., Biblical, Star Trek, comedy groups, etc.
• Dialect
– Us/them
– Honest signals of group membership
– Rapid evolution
• Dialect to language
– Vocal disguise
• Social strata and mating
Language and ToM
• Transmitting a specific message
– Is the message received? Correctly?
– Feedback
• Speech centres of brain small compared to
frontal neocortex
– ToM computationally difficult
– Understanding your/another’s mind difficult;
producing speech easier?
– Saying what we mean; metaphor; oblique
references; filling in the blanks
Language and Culture
• Are some languages better at explaining
certain ideas, concepts, abstracts?
– Latin vs. Greek
– Postmodernist theory; French vs. English
– Technical writing; German vs. English
• Selective/adaptive pressure?