Language evolution• Features of human language• Evidence for a universal grammar

– Language development– Language disorders– Pidgeons and creoles

• Animal language experiments• Fossil evidence• ESS approaches to language evolution

What is language for?

• Permits us to form internal representations of objects in our minds

• Allows us to convey what we are thinking

• Provides labels for categories of objects, i.e. dangerous vs nondangerous, which form hierarchies

Words form hierarchies

Sentences have hierarchical structure

“ This is the man all tattered and torn, who loved the maiden all forlorn, who milked the cow with the crumpled horn, that kicked the dog that chased the cat that killed the rat that ate the malt that lay in the house that Jack built”

Noun phrase structure

Universal grammar• No more than two branches spring from the same

node, but phrases can be stacked together like Chinese boxes

• Subject-verb phrase

• Verbs have argument structure, i.e. “John sleeps”, “John hit Mary”, ‘John gave Mary a present”

• Meaning depends on order, “John is hungry” ≠ “Is John hungry?”

Consequences of grammar

• Using a few rules, can produce an infinite number of sentences. All languages utilize a structurally similar grammar.

• Words must be learned and associated with objects, actions and relationships. The list of words used in a language is the lexicon.

Evidence for universal grammar

• Children follow consistent patterns of language development independent of culture

• Language disorders disrupt grammar, but not overall mental competency

• Caspar Hauser children and apes exhibit protolanguage

• Creole languages have evolved in single generations from pidgeons in many parts of the world

Infant vocal development

Word development follows object manipulation patterns

• Reduplicated consonant-vowel syllables: dada, mama

• Single consonant combined with single vowel: na (for no)

• Single consonant combined with different vowels: baby

• Initial consonant varies, but vowel remains constant: kye-bye (car bye-bye)

• Syllabic subassemblies are combined: ball

Syntax ontogeny

Grammar also follows ontogenetic pattern of object manipulation

Language aphasias

Disrupts grammar structure, but sentences are coherent

Sentences are grammatically correct, but meaningless

Both forms disrupt ability toreproduce drawings

Protolanguage

• Big train; Red Book• Adam checker;

Mommy lunch• Walk street; go store• Adam put; Eve read.• Put book; Hit ball.

• Drink red; Comb black.• Clothes Mrs G; You hat.• Go in; Look out.• Roger ticket; You drink.• Tickle Washoe; Open

blanket.

2-year old child Trained chimpanzee

Animal language studies

Caspar Hauser children

• Want milk,• Mike paint.• Applesauce buy store• At school wash face• Very sad, climb

mountain• I want Curtiss play

piano

• 13 year old girl who was imprisoned at 18 months

• Never learned to speak• Normal ability to form

concepts

Pidgeons and Creoles• Pidgeon languages are formed by people who

do not share a language, e.g. slaves in island colonies, “Forman, who carry? Carry all, cut all” or traders.

• Children of pidgeon-speaking parents form Creole languages, which have complete grammatical structure, in 1 generation. These have developed in many parts of the world with similar grammars

When did language appear in hominid evolution

Competitive hominds: Koobi Fora

Australopithecus boisei Homo ergaster

Paleolithic technology

Oldowan, 2.4-1.5 MYA Acheulean, 1.4-0.2 MYA

Cave and rock paintings

27,000 bp, Cosquer, France40,000 bp, Kakadu NP, Australia

Cave paintings

17,000 bp, Lascaux, France

Neocortex size and group size in primates

Grooming time increases with group size

Tribal group sizes

Predicted grooming times for hominoids

Global linguistic diversity

Human language diversity

• Cooperative trading requires a common language

• Conformity to a language could be used as an honest signal or group affiliation

• Expect linguistic uniformity when social networks are large, and distinct languages when networks are small and self-sustaining

Latitudinal patterns of language diversity

Language diversity and growing season

ESS approach to word evolution

• Relying on a different sound for every object requires multiple sounds which eventually become hard to distinguish

• Increase understanding by limiting number of sounds and stringing them into sequences, i.e. words.

• Expect words to evolve when there are a large number of things to name

ESS approach to syntax

• For a word to survive in a community, it must be used enough to be heard and remembered.

• Memory is constraining if all concepts require unique words

• Can increase information using syntax• In a combinatorial world, the number of words a

syntactic communicator needs to know is the sum of objects and actions, whereas a nonsyntactic communicator needs to know the product.

Syntax evolution: the problem

Syntax evolution: the answer

ESS approach to universal grammar

• Considers fitness advantage when alternative grammars are in competition

• Acquisition of correct grammar requires learning from sample sentences

• Optimal learning period occurs at intermediate number of sentences to insure coherency

• Rule-based grammars are more efficient than list-based grammars

Evolution of universal grammar

Language evolution references

Aiello, L.C. and R.I.M. Dunbar 1993 Neocortex size, group size and the evolution of language. Current Anthropology 34:184-193.

Arbib, M.A. and G. Rizzolatti. 1997. Neural expectations: A possible evolutionary path from manual skills to language. Communication and Cognition 29: 393-424.

Bickerton, D. 1990. Language and Species. Chicago: University of Chicago Press.

Bickerton, D. 1998. Catastrophic evolution: the case for a single step from protolanguage to full human language. In Hurtford, J.R., M. Studdert-Kennedy, and C. Knight (eds.) Approaches to the evolution of language. Cambridge: Cambridge University Press: 341-358.

Dunbar, R.I.M. 1993 Coevolution of neocortical size, group size and language in humans. Behavioral and Brain Sciences 16:681-735.

Hurford, J.R. 1991. The evolution of the critical period for language acquisition. Cognition 40(3): 159-202.

Nettle, D. 1999. Linguistic Diversity. Oxford University Press: New York.

Nowak, M.A., D.C. Krakauer, and A. Dress. 1999. An error limit for the evolution of language. Proceedings of the Royal Society Biological Sciences Series B 266(1433): 2131-2136.

Nowak, M.A. and D.C. Krakauer. 1999. The evolution of language. PNAS 96(14): 8028-8033.

Nowak, M.A., J.B. Plotkin, and V.A.A. Jansen. 2000 The evolution of syntactic communication. Nature 404: 495-498.

Nowak, M.A., N.L. Komarova, and P. Niyogi 2001 Evolution of universal grammar. Science 291:114-118.

Pinker, S. and P. Bloom. 1990. Natural language and natural selection. Behavioral and Brain Sciences 13(4): 707-784.

Pinker, S. 1994 The Language Instinct. New York: Harper Perennial.

Pinker, S. 1997. Evolutionary biology and the evolution of language. In M. Gopnik (ed.) The inheritance and innateness of grammars. New York: Oxford University Press: 181-208

Smith, J.M. and E. Smathmary. 1995. Chapter 17: The evolution of language. In The major transitions in evolution. New York: W.H. Freeman and Co.: 281-309.