Evolution of Language Language and Communication Week 7 Mike Dowman How does Language Change over Time? produce L1 U1 learn L2 U2 L3 U3 L4 U4 L8 U7 L7 U6 L6 U5 L5 • Each generation learns a slightly different language Cultural Evolution Many 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 Evolution L1 L2 L3 U3 L4 U4 L8 U7 L7 U6 L6 U5 • Biological evolution changes the type of languages that will evolve culturally. L5 Natural Selection Biological evolution follows quite different rules to cultural evolution. It will occur whenever we have: • Multiplication • Variation • Heredity Those genes that result in people reproducing will be selected for. Successful Reproduction • Survival • Sexual success For almost all of our evolutionary history we’ve 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 isn’t important if we’re just interested in the way language is today. • Evolution isn’t 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 Evolution Monkeys Gorillas Chimpanzees Bonobos Homo Sapiens Wrong! We are not descended from Chimpanzees Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens When did Language Evolve? Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens When did Language Evolve? Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens When did Language Evolve? Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens When did Language Evolve? Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens When did Language Evolve? Australopithecus africanus Australopithecus robustus Australopithecus afarensis Homo habilis Homo erectus Archaic Homo sapiens gorillas common chimpanzees bonobos Neanderthal Homo sapiens sapiens How long has language been evolving for? chimp-human common ancestor 5 million years ago Australopithecus afarensis Homo habilis Homo erectus gorillas common chimpanzees bonobos Homo sapiens sapiens 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 Chimpanzees • Communicate through gestures, facial expressions, tactile contact, and about 25 different vocal calls. • Calls can express fear, puzzlement, annoyance, food enjoyment, rage or distress, excitement • Can alert other chimps to a food source But much more like other animal communication systems than human languages Teaching Language to Chimpanzees Chimpanzees can’t control their breathing or vocal apparatus So can’t mimic human speech Good 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 words • Spontaneously make new lexical items • Combine words into sentences Other observers see a lot of random hand movements, and only very poor imitation of ASL signs Nim Chimpsky Nim eat Nim eat Tickle me Nim play Me banana you banana me you give Banana me me me eat No or very little syntax Up to about 250 words maximum (using a symbol board) No turn taking or conversational rules Almost always talk about immediate wants Tracing Human Evolution Problem: • Language doesn’t fossilize • No writing until 5,000 years ago So how can we track language evolution? • Skulls and skeletons • Crafted artefacts • Societal organization • Art Worldwide Spread of Humans Catastrophic Evolution There’s nothing remotely like human language anywhere in the animal world. Suggests that there never was anything halfway between chimp and human language A single mutation caused a crucial connection to be made in the brain Gradual Evolution Ugh Food We hunt Many buffalo there Ugh-Ugh Don’t attack until I say Let’s spend the winter here. It’s more sheltered and there are many animals to hunt Because out language skills got better we survived better. But it all happened slowly and gradually. Let’s take the kill back to the others I have seen herds of antelope over the hill. I think we should move there. 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. there’s 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? Gossiping • 2/3 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 Grooming • Monkeys and Apes are very social • Complex relationships • Grooming is main form of social interaction Increasing Group Size • Largest 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. • Human’s would need to spend 40% of their time to cover such a large group. Language is ‘vocal grooming’ Co-Evolution L1 L2 L3 U3 L4 U4 L8 U7 L7 U6 L6 U5 L5 • Language will adapt to humans through cultural evolution • As 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. Family • 16 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 – can’t 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 Tree F (74) – husband F (46) – husband F (17) M (16) F (12) M (8) M – wife M (20) F (18) F (43) – husband F (21) F (17) F (12) F (11) M (7) Red family members have impairment Black members have no impairment at all No spouses had language impairment M (40) – wife M (10) F (7) F (5) F (2)? F (38) - husband M (17) M (15) M (14) F (12) M (10) M (8) F (7) M (6) fraternal twins F (6) FOXP2 • In 2001a gene was found in all affected family members • No non-affected family members had this gene • Nor did any of 360 controls from the general population FOXP2 controls the expression of other genes Affects brain development (at embryo stage) Evolution of FOXP2 75 Million years ago • • • • Grey boxes mark amino acid changing mutations 0 mutations in 75 million years for chimps 1 for mice 2 for humans in last 6 million years FOXP2 Mutations • FOXP2 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 FOXP2 Does 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 Gene • Will 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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