Chapter 10 The Evolution of Language. Language Language is communication, but not all communication is language Currently, unique to humans.

Chapter 10

The Evolution of Language

Language

• Language is communication, but not all communication is language

• Currently, unique to humans

Defining Language

• 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

• 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

Motor projection areasrelated to speech

Broca’s areaWernicke’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%

25%

social leisure culture politics work

men

women

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?