What is language?

1
What is language?

• Its easy to identify language
• but not so easy to define it
• What is special about human language?
• How does it differ from forms of communication
  used by other animals?

2
Defining human language

• Human language can be defined by
• Symbolic reference abstract relation of meaning
  to symbol
• Grammar use of symbols in combinations governed
  by a syntactic ordering system

3
Grammar

• What is grammar?
• The meaning of a signal doesnt just depend on
  the symbols in the signal
• It also depends on how the symbols are put
  together
• There is no evidence that any form of animal
  communication has a grammar

4
Big Brain only?

• Language an advanced form of animal
  communication?
• Is the difference a matter of brain power?
• Counterarguments
• If this was the case, wed expect to see simple
  languages in other animals.
• We dont.
• If this was the case, the complexity of animal
  communication would be dependent on intelligence
• It isnt.

5
Animal communication systems

• A huge range of systems
• Vervet monkeys
• Whales
• Bees
• Ants

6
(No Transcript)
7
Vervet monkey Studies of Seyfarth and Cheney
8
(No Transcript)
9
Historical Theoretical Positions
Two different views of language development in
humans Skinner behavioral psychologist Chomsky
theoretical psychologist Skinner proposed that
language, like all behaviors was an operant
behavior that is formed by reinforcement and
shaping. Infants learn a language like rats
learn to get a reward by pressing a bar.
Chomsky proposed a mechanism that included
innately specified constraints on the forms that
language could take. Infants had innate
constraints on language that included
specification of a universal grammar and
universal phonetics.
10
Components of language acquisition
Three critical components of language
acquisition a. initial state of
knowledge Skinner no innate info
necessary Chomsky innate knowledge was a core
component b. mechanisms responsible for
developmental change Skinner rewards guide
change Chomskygrowth or maturation of the
language module c. the role played by ambient
language input Skinner language input did not
cause language to emerge Chomsky language
input triggers a particular pattern from those
innately stored.  
11
New view of language acquisition
New emerging view of language acquisition does
not support either an operant conditioning
model, or a selectionist model. The new model
suggests that infants engage in a new form of
learning, in which language is mapped in detail
by the infants brain.
12
Parsing the auditory world in to language units
What is the problem that an infant must
solve? Infants must learn how to parse the
auditory world, by learning to perceive the
phonetic units of speech from the formant
frequencies and learn to parse words from
running speech.
13
(No Transcript)
14
(No Transcript)
15
Evidence Neural Homologies

• Vocal calls in apes are much less under voluntary
  control than their hand movements.
• Brocas area most concerned with production of
  speech
• Wernickes area most concerned with speech
  comprehension
• Brocas area is NOT homologous with cingulate
  cortex (controlling calls) but with areas in
  pre-motor cortex for manual control, action
  recognition, and imitation possibly a mirror
  neuron system

16
Tomasellos Theory of Language Evolution and
Cultural Influence

• The ability to use symbols evolved
• These symbols were used in discourse patterns
• Over historical time, the discourse patterns
  were grammaticalised into syntax
• Symbols are a product of biological evolution,
  grammar is a product of cultural evolution

17
How to account for language evolution

• Modern human language is possible because of
  modern human genes.
• So one is tempted to explain the evolution of
  those genes.
• But what selects for language-learning genes.
• People already speaking!
• But thenlanguage should not evolveits a Catch
  22

18
But it isnt

• Not if you imagine language emerging little by
  little.
• Somebody invents the first, most primitive,
  linguistic innovation.
• Others copy it.
• Once it is stable it acts as a selection pressure
  on genes that will make learning this easier and
  faster.
• And then on to the next innovation, and so forth.

19
But what exactly do we have to explain

• Many who ponder the evolution of language spend a
  lot of time thinking about the articulatory and
  auditory mechanisms.
• But we need to explain what happened first.
• And that cant be it because our articulatory
  mechanisms will not be selected for unless people
  are already speaking.

20
But what exactly do we have to explain?

• Humans have a dramatically lowered larynx.
• puts the base of the tongue in the throat cavity
• allows movement of the tongue to modify
  simultaneously the shape of the throat and mouth
• hence exquisite vowel and pitch control
• But it also causes us to choke to death!

21
Descent of larynx and lengthening of
laryngopharynx

• Adult human larynx is lower in the throat than
  that of non-human primates and human infants

chimpanzee
human
22
A classic theory based on these observations

• Lieberman and Crelin (1971 Lieberman 1984)
  reconstructed Neanderthal vocal tract
• Proposed Neanderthals had a higher larynx than
  modern humans, which would not have permitted
  them to articulate the point vowels
• This and other speech inadequacies contributed to
  their extinction

23
(No Transcript)
24
But what exactly do we have to explain?

• You can teach chimps a little bit of symbol use.
• they can do this with their hands
• but not with their mouths.
• Humans can learn to sign as easily as they learn
  to speak
• even though in all of recorded human history
  there has been no signing
• by contrast, reading is tough
• Brain areas most associated with language are
  also associated with motor movement.

25
But what exactly do we have to explain?

• Thus, the most reasonable hypothesis is that
  language, in its origin, was gestural.
• This means a theory of language origins needs to
  worry most about the cognitive changes, not the
  physical changes that made vocal, articulated
  speech possible.

26
Why not grammar?

• Many theorists of language evolution argue that
  grammar, not symbolic reference, is what sets
  humans apart.
• As if grammar could be of any use without
  reference!
• Certainly human grammar is quite amazing, but it
  will not be selected for unless there is
  something to talk about.

27
Assume True Imitation

• Assume that our capacity for imitation improved
  beyond what we see in modern chimps.
• Assume that humans are capable of copying
  technique after observation.
• it is something that chimps cannot do, so, if
  this explains language, it also explains why
  chimps dont have it.

28
True Imitation ? model ranking

• True Imitation will select for copiers who rank
  potential models and prefer the most skilled.
• In indirect forms of learning (e.g. local
  enhancement, or goal emulation) this will not be
  true.
• Only when I obtain information directly from my
  model can the distribution of skill among
  potential models be tapped.

29

• If all you get from a model chimp is the
  association between using reeds and eating
  termites.
• If you cant learn the specifics of that models
  technique
• then you should pay no attention to skill
  differences among the models.

30

• But if you can directly acquire the models
  specific motor patterns (his/her individual
  technique), you will benefit from ranking the
  models according to skill.
• You should pick the most skilled fisher as your
  model.

31
What does this all mean for the invention of
symbolic reference?

• First, both model and apprentice benefit from
  linguistic innovations.
• The client will learn faster and better.
• Given that, other clients are bound to notice,
  and so the model will get a bigger posse of
  clients.
• In other words, the occasional model-apprentice
  genius pair has a clear incentive to get
  reference started.

32
What does this mean for the stability of the
trick?

• Since the invention of reference by such a genius
  pair will improve the quality of the learning
  experience
• This allows that model to capture most if not all
  of the client market in the population.
• And so the innovation quickly spreads to the
  whole group and is therefore stable.
• The innovation does not die with the two genius
  inventors.

33
What about the evolution of language genes?

• Given the intergenerational stability of
  reference, it can act, through a Baldwinian
  process, as a selection pressure acting on genes
  that make individuals fast learners of the
  trick of reference.
• After that it is all a series of Baldwinian
  feedback loops and the rest of the history of
  language evolution unfolds mechanistically.

34
Capacities required for linguistic innovation
Linguistic Innovation
First step
Spread to populational fixation
Selection for genes that make learning the
innovation easier (Baldwin effect)