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Evolution of human language final


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Evolution of human language final

  1. 1. Evolution of Human Language Carissa Fletcher 2.4.2012
  2. 2. Contents• Define language and its components• Relationship to social learning• Theories on how language evolved• Empirical evidence from NHP research• Evidence from genetics and the fossil record
  3. 3. Definition of Language“language can be defined as the bidirectionalsystem that permits the expression of arbitrarythoughts as signals and the reverseinterpretation of those thoughts”Fitch, Huber and Bugnyar (2010)
  4. 4. Who has language?Animals have communication systems that allowsome biologically important informationconcepts or emotions to be expressed vocally orvisually.However, humans are unique in possessing asystem which allows any concept to beexpressed and understood.
  5. 5. Components of human language in the broad sense Syntax Semantics Human Language as Large an emergent memory property Phonology Pragmatics Fitch 2010
  6. 6. DefinitionsTerm Components NatureSyntax - Word stems, affixes Computational. Structure generating - Phrases, sentences mechanisms that map between signals - Rule governing combinations and concepts. - Hierarchical ( - Recursive/self embeddingPhonology - Phonemes (fricatives, nasals, plosives Physical. Perceptual and motor systems m, p, b, f,v) underlying speech. Also, the process of - Arranged hierarchically into syllables learning requires close imitation. - Intonation, stress, prosody, rhythm - Double articulationSemantics - Meaning in the language Philosophical. Central cognitive mechanism supporting concept formation and expressionPragmatics -What the speaker intends Psychological. Requires an ability to infer - Mittelungsbedurfnis intentions of a signaller which can be - (Shared attention system, Theory of based on indirect cues such as ‘gaze Mind mechanism direction’. Also, sharing inner thoughts relies on an understanding of the thoughts of another (ToM)
  7. 7. Language – its relationship to social cognition and cultureAdvanced social cognition isrequired for children to acquirelanguage as sophisticated “mindreading” abilities needed to Social Languagededuce word meanings and to cognitioncommunicate pragmatically.Once in place language itselfbecomes a tool for socialcognition becomes central toHuman Culture.
  8. 8. Language diversity- Over 6000+ differentlanguages globally- Darwin saw similarities between the evolution of species and the evolution of languages. Grey et al. 2010 NeighborNet analyses of the Indo- European linguistic items
  9. 9. Theories on how language evolved?1. Innate biological system- System of cognitive structures develop and are genetically determined.- There are some shared computational commonalities between all languages e.g. Universal Grammar(Chomsky 2007)- language syntax shows evidence of complex design – similar to, for example, the visual system. “biological adaptation is the only way to explain the appearance of such design”.(Pinker 2003; Nowak 2001)
  10. 10. 2. Usage based system:- Human language is symbolic- We evolved cognitive skills enabling the use of symbols- social-cognitive and social-motivational infrastructure needs to be in place before language could arise in humans.- Human communication is a fundamentally cooperative enterprise that could not have arisen without the shared intentionality.- Shared intentionality allows for the emergence of naturally intention directing gestures (pointing and miming)Tomasello(2008)
  11. 11. 2. Usage based system:- The close relationship between manual gesture and vocalization(in the form of speech via mirror neurons Corballis (2003)- Cooperative hunting, food savaging and food sharing have been powerful drivers of the information sharing capacity embodied in language.- suggested that the capacity Bickerton (2010) of displacement in human language
  12. 12. Comparative approach1. Shared vs Unique?2. Gradual or non-gradual evolutionof this feature?3. Continuity orexaptation? Fitch 2010
  13. 13. Vocal Production in Primates ~ 63Mya- NHP calls develop under strong genetic influences (Hammerschmidt and Fischer 2008)- Vocal plasticity in NHP the Mouse form of acoustic lemur convergence at the group level has now been well documented.- Mouse lemurs; Hafen et al. 1999,- Japanese macaques, - high degrees of social affinity also produced- Chimpanzees (Tanaka 2006) acoustically more similar calls independent of genetic- Marmosets (Snowdon 1999), relatedness (Lemasson 2011).- Campbells monkeys (Lammasson ? neural circuits involved in the generation of vocal calls 2004; Ouattara 2009 in NHP are radically different from those involved in human speech(Jürgens, 2002).
  14. 14. Language affixationCotton Top Tamerins can learn anaffixation pattern that sharesimportant information with our owninflectional morphologye.g. the rule that adds ‘-ed’ tocreate the past tense(Endress et al. 2009)
  15. 15. Method‘shoy’ = affix‘bi’, ‘ka’, ‘na’, ‘to’, ‘gu’ ,‘lo’, ‘ri’ and ‘nu’ = familiar stems‘brain’, ‘breast’, ‘wasp’, ‘snake’ and ‘swan’ = test stems1. Familiarised subjects to bisyllabic items conforming to either a pre-fixation or suffixation pattern they heard 14 words 70 times.2. TEST ‘shoy’- ‘bi’ or TEST ‘ka’- ‘shoy’a. Half the subjects tested on the pre-fixation pattern and 29 days later the suffixation patterna. The other half tested suffixation pattern first and 33 days later the pre-fixation pattern
  16. 16. Results The monkeys orientated more towards violations that consistent conditions Cotton Top Tamerins can learn a rule formally similar to affixation patterns in humans-suggest that this domain specific mechanism shared across humans and NHP
  17. 17. Combinatorial signals Human speech uses a rule-governed assemblage of morphemes into more complex vocal expressions. Loud alarm calls Hack= Pyows =Putty nosemonkeyArnold and Zuberbuhler Playback2004 experiments Pyow-Hack = ‘Group progression’
  18. 18. Supporting theories Innate Biological System
  19. 19. Evidence from gestures Association of manual and facial/vocal signals in groups of chimpanzees and bonobos, - 31 manual gestures - 18 facial/vocal signals. • Gestures seem less closely tied to particular emotions, such as aggression or affiliation,• possess a more adaptable function and likely under greater cortical • Candidate modality to have acquired control than facial/ vocal signals symbolic meaning in early hominins?
  20. 20. Symbolic language • Washoewas taught over 100 manual signs,3 based loosely on American Sign Language (ASL) • Combine signs into two- or three-‘‘word” sequences to make simple requests (Gardner & Gardner, 1969).Kanzi –large vocabulary, based on pointing to symbols on a keyboard + gestures-limited to only two or three ‘‘words”.-follow instructions conveyed in spoken sentences with as many as seven or eightwords (Savage-Rumbaugh, Shanker, & Taylor, 1998).-roughly equivalent to that of a 2½-year-old girl (Savage-Rumbaugh et al., 1998)
  21. 21. Supporting theories Usage based system
  22. 22. Genetics-KE family show no activation in Broca’s area while covertlygenerating verbs (Liégeois et al., 2003). Point mutation in FOXP2-FOXP2 gene in humans is involved in the cooption of vocalcontrol by Broca’s area (Corballis,2004a).-Highly conserved in mammals,FOXP2 gene underwent two mutations since the splitbetween hominid and chimpanzee lines.- ‘‘some 10,000–100,000 years ago” (Enardet al., 2002) it not KE familyunreasonable to suppose that it coincided with theemergence of Homo sapiens around 170,000 years ago.-Recent evidence that the mutation is also present in theDNA of a 45,000-year-old Neandertalfossil, suggesting thatis goes back at least 300,000– 400,000 years to the commonancestor of humans and Neandertals(Krause et al., 2007).
  23. 23. Fossil Record-Fossil evidence suggests that the anatomical requirements forfully articulate speech were probably not complete until theemergence of H. sapiens.e.g. hypoglossal nerve (see image), which passes through thiscanal and innervates the tongue, passes through thehypoglossal canal, and this canal is much larger in humans thanin great apes, probably because of the important role of thetongue in speech.- Fossil evidence suggests that the size of the hypoglossal canal in early australopithecines, and Homo habilis, was within the range of that in modern great apes,- the Neanderthal and early H. sapiens skulls was contained well within the modern human range (Kay, Cartmill, & Barlow, 1998)
  24. 24. Summary• Define language and its components• Relationship to social learning• Theories on how language evolved• Empirical evidence from NHP research• Evidence from genetics and the fossil record