The evolution of language:some beginnings

Maggie Tallerman

Newcastle University, UK

UQAM Summer Institute in CognitiveSciences, June 2010

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Outline

!"Becoming human – from thepre-linguistic to aprotolinguistic stage

#"What counts as evidence inevolutionary linguistics?

$"The concept of protolanguage

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1. Becoming human% DNA: Humans and

chimpanzees/bonobosshare a LCA 6—8mya

% A social ape but nolinguistic abilities

% What crucial steps inhominin physical andcognitive evolutionoccur in last 6mya?

% Changes in earlyhominin niche?

% Specific selectionpressures?

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Some hominin landmarks:Ardipithecus ramidus

% 4.4mya

% Largely tree-dwelling, but couldwalk upright.

% Bipedal on theground - no knucklewalking.

% Ape features andhominin features.

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The Laetoli footprints Tanzania (3.6mya)

% Australopithecusafarensis (Lucy)

% 3.2mya

% Ape-sized brain ~400cc

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Stone tools datefrom 2.6mya

Oldowantechnology;simple to make;but more complexthan ape tools.

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Homo habilis 2.4 – 1.4mya

•Post-datesearliest tools•Brain islarger:500—600cc.•Still v. welladapted toclimbing

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Homo erectus / ergaster – the first human?

% Circa 1.9mya till 0.3mya

% Fully bipedal now

% Brain size increase to900cc by 1.5mya.

% Acheulean tools: 1.6mya

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Major changes from LCAwith chimps to H. erectus

% Niche changes (habitat, diet, scavenging,extractive foraging, cooked food ...)

% Physical changes (bipedalism, larynx lowering,manual dexterity, reduction in gut & tooth size,brain growth / reorganization ...)

% Life history changes (long infancy, parental careincreased ...)

% Cognitive changes (docility, co-operation, toolsophistication, sharing, theory of mind ...)

% Vocal imitation/ learning/ control/practice?

% Protolanguage: first users?

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Transition to AnatomicallyModern Humans

% Speciation of Homo sapiens c. 195kya

% Brain stops growing 150kya; modernsize 1345cc.

% H. sapiens disperses Out of Africa within120kya; reaches Australia by ~60kya.

% Assume a fully-modern language facultyin place around 200kya?

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2. What counts as evidence inthe field of language evolution?

% Evidence for what? Do we agree whatLanguage is? Mere behaviours? Or a cognitiveentity?

% Assume a language faculty: a geneticallyencoded system for language learning, underpositive selection in hominin lineage.

% Language not a feature but a complexpackage of features.

% Evolutionary precursors? Some aspects nowuniquely human and (likely) uniquelylinguistic. (FLB / FLN)

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What counts as evidence in thefield of language evolution?

% Archaeology: from artefacts etc.,inferences about development ofsymbolic communication and linguisticcomplexity?

% Paleoanthropology: fossil record –anatomical evidence for speech, brainstructure?

Direct evidence? Artefacts and bones!

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Evidence from archaeology

% Can symbolic behaviour be evidence ofsymbolic thinking (referential words)?

% Can hierarchically-structured toolmanufacture be evidence of hierarchically-structured language?

% Problems:% no evidence for either of these inferences

% much material doesn’t fossilize! (absence ofevidence not evidence of absence)

% the Martian archaeologist’s view of 1750—2000!

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Evidence fromarchaeology/neuroscience

% Vocal imitation/control/learning relate to manualimitation/control/learning (tool use):

% Manual imitation/practice and vocal imitation/practiceuse a number of the same neural areas (e.g. Lieberman2000)

% Broca's area is involved in both manual and vocalcontrol (Greenfield 1991).

% Brain activity: different activation patterns when makingcomplex hand axes (from Acheulean on) vs. earlyOldowan stone tools (Dietrich Stout, 2007, 2008).

% Neural circuits supporting stone toolmaking partiallyoverlap with language circuits.

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% Brain size is not hard to detect – andgrowth suggests clear lifestyle changes

% Brain tissue expensive to maintain!

% Brain function is impossible to detect

% Re-organization of neural connectionscrucial for language; timings unknown.

% Little to be gained from fossil endocasts

Evidence frompaleoanthropology

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Evidence from paleoanthropology:selective pressures for speech

% Permanent, major descent of a) larynx and b)hyoid bone, resulting in curved tongue anddistinctive reshaping of vocal tract.

% Probably occurred in erectus, linked withobligate bipedalism.

% Enhanced breath control for speech notpresent in erectus, but present inheidelbergensis (MacLarnon 2011)

% Problems:% Relevant physical structures don’t fossilize% Gaps and incompleteness in fossil record% Hard to interpret% Can speech capacities indicate status of language faculty?

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What counts as evidence in thefield of language evolution?

Comparative biology, primatology:

% natural communication systems of closely-related species (vocalizations / gestures);

% aspects of primate cognition not used incommunication (e.g. social hierarchies)

% latent language-related abilities (revealed inALR, e.g. Kanzi and Savage-Rumbaugh);% What was present in the LCA to build on?

% Versus convergent evolution of learnedcommunication systems (birds, cetaceans…).

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Evidence from biochemistryand neuroscience

% Biochemistry / molecular biology:% DNA/genetic evidence

% Positive selection for language-relevant genes

% Neuroscience% Mirror neurons

% Brain imaging

% Studies of language deficits and disorders

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% Exercise caution: see Rudie Botha’s work on“windows” (proxies) for language evolution.

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What counts as evidence in thefield of language evolution?

Linguistics and related fields: indirect evidence% Observable ‘language genesis’ in modern humans

(e.g. pidgins/creoles; emergent signed languages);% ontogenetic development: language in infants;% psycholinguistic experiments;% language disorders (e.g. SLI, the KE family...)% Modern languages – extrapolating from known

linguistic data, including historical development,particularly grammaticalization.

% Models of language evolution:% computational and mathematical modeling;% robotics;% evolutionary game theory

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Language genesis suggests alanguage faculty exists

% Emergent sign languages –Nicaraguan Sign Language,

Al-Sayyid Bedouin SignLanguage

% Homesign (e.g. Goldin-Meadow)

% Properties:% signs iconic, never arbitrary

% child’s signs are structured andsegmented – unlike “input” fromhearing parents’ signs

% does have consistent ordering:patient-action & action-agent

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Grammaticalization: N and Vsource of all word classes

% Proto-nouns and proto-verbs have roots in primateconceptual structure (Bickerton 1990, Hurford 2007,Tallerman 2009); bought “for free” and show up inALR)

% Heine & Kuteva (2007): nouns source of all othergrammatical categories, inc. verbs.

% Trajectories of grammaticalization predictable% Auxiliaries from lexical verbs (useta, gonna, hafta, keep)% Prepositions from lexical verbs (concerning, regarding, during)% French pas (NEG) < pas (N: a step)% Demonstratives > complementizers (that, German dass)

% Need not account for ALL word classes or invent newfactors behind their appearance.

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3. Protolanguage:contrasting views

!" No Protolanguage stage; language capacity veryrecent; arose abruptly in H. sapiens (maybe only50,000 ya). (e.g. Piattelli-Palmarini, Cedric Boeckx)

% Language doesn’t evolve “for” communication% and isn’t shaped by communication% Adaptationist scenarios too simplistic (random genetic drift

might play a big role)% No words without syntax (so no PL)% Merge is the key operation (but composite “merged” tools

found from at least 200kya!)

#" Language evolved gradually over past two millionyears, going through various protolanguage stages(Bickerton, Jackendoff, Fitch, Hurford...) in earlierspecies. Broadly adaptationist.

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Assuming protolanguage% Modality:

& vocal / auditory & gestural (Corballis, Arbib)& a mix of modalities

A holistic PL? (Arbib, Wray, Fitch)

% No words, each utterance initially anon-compositional whole message

% words “fractionate” out as coincidentalphonetic similarities among holisticutterances noticed.

% e.g. tebila / lapatu buys la = meat% Tallerman 2007, 2009 critique of holistic PL

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Musical protolanguage?(Fitch)

% Strong indications that protolanguage did not evolvefrom innate primate calls.

% Vocal learning / vocal imitation / vocal control – anevolutionary novelty in the primate lineage.

% But convergent evolution of these properties in otherlineages, e.g. some songbirds, whales, seals...

% Gives rise to song-like communication.% Selection pressures here – sexual selection% Indicate why/how a learned vocal system evolves.

“Song possesses the characteristics ofopenness and generativity, as well as culturaltransmission, ... needed for language” (Fitch2010)

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Musical protolanguage as“bare phonology” (Fitch 2010)

% “Bare phonology has an obvious non-linguistic parallel in humans in the formof music, particularly non-lyrical song.”

% “MPL provides meaningless buthierarchically structured signals, whichinclude phrases...”

% “The generative aspect of phonology ...emerged before it was put to anymeaningful use.”

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Problems with musicalprotolanguage

% Fitch: “complex phonological structure” existsbefore meaning. Wrong way round!

% Contrastive phonology only emerges underselective pressure from expanding vocabulary(Studdert-Kennedy, MacNeilage, Lindblom,De Boer, Oudeyer)% In ontogeny, vocabulary growth gives rise to

particulate phonology; and in evolution?% In computer models: Lindblom (1998): “The

formation of sound structure is semanticallydriven. Phonological units are emergents ofthe developing lexical system rather thanprespecified entities.”

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Problems with musicalprotolanguage

% Perceptual discriminability shapes vowel systems(Lindblom, de Boer, Oudeyer); keep each vowel inthe set as far apart as possible. Relies on meaning!

Sexual selection for language faculty unlikely.% No biological link between human music and

animal ‘song’ (Patel 2008):% ‘Song’ is mere acoustic display, not created '

% ‘Song’ arises at puberty '

% ‘Song’ – v. limited messages (territorial, mating) '

% ‘Song’ mostly produced by males and has seasonalpeaks, driven hormonally '

% ‘Song’ acquisition has critical period (( for Lg) – butmusic not '

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Where do phrasescome from? Heads!

% Fitch: phrases / hierarchical structure evolvein MPL (but “phrases” in animal song NOTsimilar to language; cf. Hurford, in press);

% Fitch: phrases are EXAPTED by syntax when‘holistic’ protolanguage is resolved intodistinct words.

% Wrong way round! Phrases in syntax muststart with a bare head (proto-N, proto-V)

% Heads subsequently acquire modifiers(obligatory and optional); Jackendoff (2002).

% Heads come first!

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Word-based protolanguage (Bickerton, Jackendoff)

% The evolution of the lexicon: conceptualknowledge distinct from lexical knowledge.

% Much evidence that labels (words) aid thelearning of categories (in infants and apes).

% Even labelling items for oneself is adaptive(the two mushroom scenario)

% Assume a proto-word stage, wherephonological representations are linked tosemantic representations; but no syntax.

% For the rest, read Jackendoff and Bickerton!

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Thank-you! The end