Evolution of Language

Language and CommunicationWeek 7

Mike Dowman

How does Language Change over Time?

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produce learn

• 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

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

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 EvolutionMonkeys

Chimpanzees

Gorillas

Bonobos

Homo Sapiens

Wrong!

We are not descended from Chimpanzees

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

When did Language Evolve?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

When did Language Evolve?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

When did Language Evolve?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

When did Language Evolve?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

When did Language Evolve?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Archaic Homo sapiens Neanderthal

Homo erectus

Homo habilis

Australopithecus afarensis

Australopithecus africanus Australopithecus robustus

How long has language been evolving for?

gorillas common chimpanzees bonobos Homo sapiens sapiens

Homo erectus

Homo habilis

Australopithecus 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 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 sourceBut 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 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 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 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 Evolution

Problem: • Language doesn’t fossilize• No writing until 5,000 years agoSo 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 EvolutionUgh

Ugh-Ugh

FoodWe hunt

Many buffalo there

Don’t attack until I say

Let’s take the kill back to the others

I have seen herds of antelope over the hill.

I think we should move there.

Let’s spend the winter here. It’s 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. 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

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• 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 TreeF (74) – husband

F (46) – husband M – wife F (38) - husbandF (43) – husband M (40) – wife

F (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 impairment

Black members have no impairment at all

No spouses had language impairment

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

• 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

75 Million years ago

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.