Origins structure and evolution of langauge What

Origins, structure and evolution of langauge

What is language? • Communication – Signals emitted by an organism whose function is to influence other organisms (of the same species) • Symbolic – There is little or no relationship between nature and meaning of the signal • Generative – Different combinations of the same signals

Do other primates have language? • Vervet monkeys – Warning vocalisations specific to eagle, snake, leopard • Rhesus monkeys – Can distinguish vocalisations such as [p] from [b] (like infants) • Chimpanzees – Wild animals highly vocal – Nim Chimpsky signing patterns (food item first, name at end) – Kanzi (bonobo) word order preferences using pictograms

Human-specific language innovations • Physical changes – Lower larynx gives greater range of vocalisations – Nasal cavity can be sealed off giving greater range of vowel sounds – Muscular tongue • Elaboration of brain areas (Left Cortex) – Broca’s area (production) – Wernicke’s area (reception)

Language fossils • Artefacts • Genes – Language must be at least as old as the ancestor of modern humans – Genetic similarities between populations reflect linguistic similarities • Possible universal cognates – AQ’WA = water – TIK = finger, one – MAMA, PAPA

Linguistic diversity • 5, 000+ extant languages; many dialects • 100 s of language groups (Indo-European is just one!) • Huge grammatical and phonetic diversity – – Immutable/inflective/agglutinating Fixed/free word order Subject/topic prominent SVO/SOV/VSO He is eating for her English Näïkìmlyìïà Kivunjo (Bantu)

Language groups in Europe • Sir William Jones, 1786 – Recognised relationships between different languages pointed to common origin Semitic Arabic Sanskrit Avestan Clas. Greek Latin Gothic Turkish Turkic Old Irish Indo-European Hebrew

How do languages evolve? • Changes in word use – Nouns become verbs (mail), adjectives change meaning (cool), • Origin/loss of cognates – Hound original term, ‘dog’ appears later • Changes in pronunciation – The great vowel shift (15 th C. ). E. g. mood previously pronounced ‘mode’, house pronounced with vowel sound of ‘loose’ • Changes in grammar – Loss of gender in English, disuse of ‘thou’, ‘whom’

Why do languages evolve? • Cultural exchange – Denim, Tennis, Dandelion, Assassin • Novel situations – Surfing, cookie, blog • Phonetic laziness! – Water pronounced as ‘wadr’ • Identity and slang – Coded meaning (e. g. rhyming slang)

Universal Grammars • All individuals have an inbuilt potential to generate grammatical structures – These consist of nouns, verbs, subject-object-indirect object relations, clause structures, etc. • To a large extent this universal grammar (UG) is hard-wired – Wild-children (e. g. Genie) develop protolanguage in absence of stimulus – Genetic basis of specific language impairment – Children’s generalising ability (e. g. wugged) • Differences between languages in phonemes, words and grammatical parameters

Language trees S VP NP det NP N The student V failed det N the test

Stochastic grammars • We can describe sentences by sets of generative rules Rule Meaning S → NP VP Sentences consist of a noun phrases and a verb phrase NP → N [PP] A noun phrase consists of a noun and possible a preposition phrase PP → P NP A Preposition phrase consists of a preposition and a noun phrase VP → V NP A verb phrase consists of a verb and a noun phrase S → if S then S A sentence can consist of two sentences joined by an if. . then. . construction

Language parameters • Major differences in grammatical structure can be due to small differences in grammatical parameters Baker (2003)

• Major difference is presence/absence of polysynthesis – If present word order flexible but word structure complex and rigid – E. g. in Mohawk participant must be named in the verb that names the event Rukwe’ wa-sh-ako-hsir-u ne owira’a Man past-he-her-blanket-gave the baby Baker (2003)

Why do grammars evolve? • Drift in small populations – Individuals make errors – In small populations errors may be passed between generations • Encryption (Baker, 2003) – Encoding messages so that only a select few can interpret the answer may be important – Letter substitution = Phoneme differences, Transposition = parameter differences – Navajo code talkers of WWII

• Grammatical structures are an example of stochastic grammars – Generate algorithms for constructing strings – E. g. stochastic context-free grammars (SCFGs) consist of terminal states generated by internal states independent of context E. g Rule Meaning S → a. Wb Start produces terminals (a, b) and internal state (W) W → a. Yb Internal states generate terminals (a, b) and convert to other states (Y) W→n STOP Note that there might be many different types of internal state, each of which generates certain sets of terminals and other states. E. g. NP generates terminals (nouns, determiners, adjectives) and other states (PP, NP, …)

Stochastic Grammars in Bioinformatics S → LS | L F → d. Fd | LS L → s | d. Fd s = unpaired bases d = paired bases S = non-terminal producing loops F = non-terminal producing stems L = non-terminal producing unpaired bases or new stems Knudsen and Hein (1999). Bioinformatics 15: 446

How do we understand language? • For stochastic grammars there is a dynamic programming solution that allows us to consider all possible parsings of a given string S VP VP NP V* PP NP NP N Adv V det N P det N I once shot an elephant in my pyjamas Groucho Marx

Is this how humans learn and process? • Th hmn cpcty fr dcdng mprfct sgnls s rmrkbl • We unexpected grammar can even sense make of • Humans … predictive … to … in … gaps • iasudiahsuandcanquicklyspotpatternssdfskkdflgdfkgmfk

References • • Pinker, S. (1994) The Language Instinct. Penguin Burchfield, R. (1985) The English Language. OUP Aitchison, J. (1996) The Seeds of Speech. CUP Ruhlen, M. (1994) The Origin of Language. Wiley Crystal, D. (1987). The Cambridge Encyclopedia of Language. CUP Purves, D. et al (2000). Neuroscience. Sinauer Baker, M. (2003). Linguistic differences and language design. Trends Cog. Sci. 7: 349 • Nowak et al. (2001). Evolution of universal grammar. Science 291: 114 • Durbin et al. (1999). Biological Sequence Analysis. CUP