Transcript Evolution of Language - Linguistics and English Language

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.