Evolution of Language Slides (1)

Evolution of LanguageLanguage and CommunicationWeek 7

Mike Dowman

How does Language Change over Time?Each generation learns a slightly different languageL1L8L7L6L5L4L3L2U1U6U5U4U3U2U7producelearn

Cultural EvolutionMany factors affect how language will change from generation to generation.What people talk about.Who talks to who how often.What psychological learning mechanism people have.Ideas about what sounds good, or who people want to sound like.

Biological EvolutionBiological evolution changes the type of languages that will evolve culturally.L1L8L7L6L5L4L3L2U6U5U4U3U7

Natural SelectionBiological evolution follows quite different rules to cultural evolution.It will occur whenever we have:MultiplicationVariationHeredityThose genes that result in people reproducing will be selected for.

Successful ReproductionSurvivalSexual success

For almost all of our evolutionary history weve been hunter-gatherers.How does language help hunter gatherers?Does language ability affect social status?Does language play a role in courtship?

Does Language Evolution Matter?Language evolution isnt important if were just interested in the way language is today.Evolution isnt important for understanding the structure and functioning of animals and plants.

The evolutionary perspective helps us to understand all aspects of language.

Evolution of all Life

Primate EvolutionWrong!

We are not descended from Chimpanzeesgorillas common chimpanzees bonobos Homo sapiens sapiensArchaic Homo sapiens NeanderthalHomo erectusHomo habilisAustralopithecus afarensis Australopithecus africanus Australopithecus robustus

When did Language Evolve?gorillas common chimpanzees bonobos Homo sapiens sapiensArchaic Homo sapiens NeanderthalHomo erectusHomo habilisAustralopithecus afarensis Australopithecus africanus Australopithecus robustus

How long has language been evolving for?gorillas common chimpanzees bonobos Homo sapiens sapiensHomo erectusHomo habilisAustralopithecus afarensis 5 million years agochimp-human common ancestor

What has evolved?Chimpanzees give clues to how we were 5 million years ago.How does modern chimpanzee language compare to human language?Do chimpanzees have all the cognitive prerequisites for language? (Even if they could speak, would they have anything to say?)

Wild ChimpanzeesCommunicate through gestures, facial expressions, tactile contact, and about 25 different vocal calls.Calls can express fear, puzzlement, annoyance, food enjoyment, rage or distress, excitementCan alert other chimps to a food sourceBut much more like other animal communication systems than human languages

Teaching Language to ChimpanzeesChimpanzees cant control their breathing or vocal apparatusSo cant mimic human speechGood manual control So several attempts to teach chimpanzees American sign language (ASL) Or to communicate by pointing to a board of board of symbols

What can Chimps Learn?Chimp trainers have claimed:Chimps can learn 250 ASL wordsSpontaneously make new lexical itemsCombine words into sentences

Other observers see a lot of random hand movements, and only very poor imitation of ASL signs

Nim ChimpskyNim eat Nim eatTickle me Nim playMe banana you banana me you giveBanana me me me eatNo or very little syntaxUp to about 250 words maximum (using a symbol board)No turn taking or conversational rulesAlmost always talk about immediate wants

Tracing Human EvolutionProblem: Language doesnt fossilizeNo writing until 5,000 years agoSo how can we track language evolution?Skulls and skeletonsCrafted artefactsSocietal organizationArt

Worldwide Spread of Humans

Catastrophic EvolutionTheres nothing remotely like human language anywhere in the animal world.Suggests that there never was anything halfway between chimp and human languageA single mutation caused a crucial connection to be made in the brain

Gradual EvolutionUghUgh-UghFoodWe huntMany buffalo thereDont attack until I sayLets take the kill back to the othersI have seen herds of antelope over the hill. I think we should move there.Lets spend the winter here. Its more sheltered and there are many animals to huntBecause out language skills got better we survived better. But it all happened slowly and gradually.

What is Language for?Language helps us to pass on and develop technologies (how to make better spears).It helps us to coordinate activities (e.g. hunting).We can communicate knowledge about relevant aspects of the environment (e.g. theres a big herd of buffalo behind the hill where we camped 5 days ago).

Could we achieve any of this without language?Could we even think this without language?

Gossiping2/3 of all conversation is about social relations.Both in developed countries and for hunter-gatherers. Does this kind of language use have any effect on our fitness?Does it help our survival rate?Does it increase our reproductive success?

Language Evolved as a Substitute for GroomingMonkeys and Apes are very socialComplex relationshipsGrooming is main form of social interaction

Increasing Group SizeLargest group size for non-human primates is 50-55 (Chimps and Baboons).For modern hunter-gatherers is about 150.Primates spend up to 20% of their days grooming.Humans would need to spend 40% of their time to cover such a large group. Language is vocal grooming

Co-EvolutionLanguage will adapt to humans through cultural evolutionAs soon as we acquire a tendency to mimic some form of language will appear

Has Language Evolution Stopped?Is there genetic variation in language ability between different people?Are mutations still occurring?

If either of these are true, language is still evolving.

The K.E. Family16 of 30 members of K.E. family have a specific language impairment.Problems with morphology (have to learn past tense and plurals one by one cant learn rule of adding ed / -s).Some other aspects of grammar not so affected.Mean IQ of impaired subjects 86 (range 71-111).Mean IQ of unaffected family members 104 (range 84 119).

K.E. Family TreeF (74) husbandF (46) husbandM wifeF (38) - husbandF (43) husbandM (40) wifeF (17)M (16)F (12)M (8)

M (20)F (18)

F (21)F (17)F (12)F (11)M (7)

M (10)F (7)F (5)F (2)?

M (17)M (15)M (14)F (12)M (10) M (8)F (7)M (6)F (6)

fraternal twinsRed family members have impairmentBlack members have no impairment at allNo spouses had language impairment

FOXP2In 2001a gene was found in all affected family membersNo non-affected family members had this geneNor did any of 360 controls from the general populationFOXP2 controls the expression of other genesAffects brain development (at embryo stage)

Evolution of FOXP2Grey boxes mark amino acid changing mutations0 mutations in 75 million years for chimps1 for mice2 for humans in last 6 million years75 Million years ago

FOXP2 MutationsFOXP2 mutations have been selected for in humans (are not due to random drift).Mutation probably happened 10,000 to 100,000 years ago.

KE family mutation is different in a completely different part of the gene.But may still give us some idea what the mutations were for.

Implications of FOXP2Does FOXP2 really tell us anything about language evolution?Does FOXP2 code for morphology?Or does the mutation of FOXP2 disrupt whatever codes for morphology?Does FOXP2 suggest that something really language-specific evolved?

The Future of the KE Family GeneWill the KE family gene die out?Or will it keep spreading?

If it spreads widely enough, a version of language without morphological rules might arise.We could be seeing the beginnings of a new stage in the evolution of language.

Summary Language evolution raises a lot of questions:What evolved?When did it evolve?Why did it evolve?

Key point All explanations in linguistics must ultimately be grounded in terms of biological evolution by natural selection.

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Evolution of Language Slides (1)