Evolution of Speech and Language

Question 1

Why do people think we shouldn’t study the evolution of speech?

Answer 1

Very risky, it has only evolved in one way - in our species

usually we study a comparative trait, but we can’t do this as it hasn’t evolved in other species

Question 2

What happened in 1866?

Answer 2

The linguistic society banned all discussions on this topic because it wasn’t scientific

however, a interdisciplinary approach (combines different methods) can yield a possible scenario

Question 3

What are the controversies about language evolution?

Answer 3

Chomsky/gould - language couldn’t have evolved through natural selection, but as a by product of selection for other abilities or as a consequence of as yet unknown laws of growth and form

Pinker - natural selection is more than sufficient to explain the evolution of language, no different from echolocation or stereopsis - the language organ is no different to the vertebrate eye, elephant trunk, only explained by natural selection

Question 4

Why does Chomsky believe that evolution hasn’t evolved through natural selection?

Answer 4

Not enough genetic variation - either can speak or not
Confers no selective advantage - at an individual level
Would require more evolutionary time and genomic space than is available

Question 5

What does language require?

Answer 5

A range of central/peripheral specialisations - not all necessarily evolved to specifically have a function as language and speech

Question 6

What does pre adaptation / exaptation mean?

Answer 6

When a trait or a feature has a function which is unrelated to the reasons for its origination - language may have evolved at a certain stage in our evolution when key innovations had already evolved for other functions

Question 7

What are the previous claims of uniqueness?

Answer 7

Fast mapping, categorical perception, descended larynx.. these are wrong

Question 8

What is human evolution?

Answer 8

We have evolved from our common ancestor or modern apes and humans that lived 6-7 million years ago

Question 9

When did we evolve?

Answer 9

6-7 million years ago

Question 10

What makes humans unique?

Answer 10

Our ability to walk upright, on their legs only: bipedalism

Question 11

What does language require?

Answer 11

Ability to memorise large numbers of symbolbs
large amount of cognitive memory
syntactic, recursive thought; ability to organise and embedded series of ideas
ability to learn via imitation

Question 12

What does speech require?

Answer 12

ability to plan, produce and perceive flow of sounds
sophisticated control of articulators and breathing
a vocal apparatus capable of produce a large variety of sounds

Question 13

How much information does our brain need to store?

Answer 13

The neocortex of the human brain must be able to store lots of information acquired through learning:

vocal (10,000-1000,000 words)
grammar
multiple ways that can be said and cannot be said

Question 14

What is increase in brain size essential for?

Answer 14

The emergence of language in human communication

Question 15

When did hominids acquire a large brain?

Answer 15

Brain size is not larger than expected from their body size

It began to increase relative to body size with genus Homo, 2 million years ago

Question 16

What are the costs of having a large brain size?

Answer 16

It is only 2% of our body weight but consumed 20% of our energy
Human babies are born premature, pregnancy should last 17 months

but there are selective advantages to make it worth while

Question 17

Why is the brain so large?

Answer 17

To enable language/social cognition
3 hypothesis - machiavellian intelligence hypothesis, social contract hypothesis and the Scheherazade effect
For other reasons, hunting, fishing

Question 18

Machiavallian intelligence or social brain hypothesis

Answer 18

Evolution of increased brain size is a result of selective pressures favouring individuals capable of ealing with increasingly complex social relationships (as social group size increased)

problem: they could live in a large group because of large brain or vice versa

Question 19

The social contract hypothesis

Answer 19

A large brain and language has evolved to facilitate symbolism
symbolism is necessary to enable the coordination of complex social contracts (marriage) rendered necessary by hunting
need language to understand each other

Question 20

The Scheherazade effect

Answer 20

Verbal skils have evolved as an indicator of gene quality - selection for by sexual selection

Question 21

What does the prefrontal lobe play a role in?

Answer 21

Critical role in planning and decision making, two abilities that are central to speech - speech is made of linear sequence of symbols that require a speaker to plan ahead to decide what to say and how to say it - planning suppresses freedom

Question 22

What did people believe about the prefrontal lobe?

Answer 22

That is was more developed relatively to other neocortical areas when compared to other non human primates

Question 23

Why is the idea about the prefrontal lobe being larger not correct?

Answer 23

Recent studies using MRI have showed that the human frontal lobe is not relatively larger than those of other apes

Question 24

What do mirror neurons do?

Answer 24

Neurobiologists have discovered neurons in monkey’s brains that fire both:
when the animal performs a particular movement and when it observes another animal performing this movement

Question 25

Where are mirror neurons located in?

Answer 25

Located in both hemispheres in the area F5 of the premotor cortex, the homologue of Broca's

Question 26

What do the mirror neurons do?

Answer 26

Enable mapping of perception onto execution - provide a starting point for the evolution of imitation abilities required for the evolution of language

Question 27

Where are the differences in cortical-laryngeal neurons in non human mammals and humans?

Answer 27

Nonhuman mammals - they have no direct connection to the neurons that control the muscle of the tongue and larynx Humans have direct connections to the laryngeal motor neurons that control the muscles of the larynx

Question 28

What does Broca's area play role in?

Answer 28

The production of speech

Question 29

What does Wernicke's area play a role in?

Answer 29

The perception of speech

Question 30

Broca and Wernicke's area in the past

Answer 30

They were differentiated in Homo Habilis as early as 2 million years ago

Question 31

What does speech require?

Answer 31

Sophisticated control of breathing - breathing without voicing uses the diaphragm is controlled by the vagus nerve

Question 32

How do your control the intonation / speech of breathing?

Answer 32

The air pressure in the trachea, just below the larynx must remain constant regardless of how full the lungs are

Question 33

How to achieve complex control of the air pressure in the trachea?

Answer 33

Use the muscles of the thorax and the abdomen, which are controlled by the thoracic region of the spinal cord - thoracic breathing

Question 34

What is the thoracic vertebral canal in humans?

Answer 34

Larger in modern humans than in other primates and in our ancestors

Question 35

Why were early humans not capable of speech?

Answer 35

Because they weren't able to control their breathing

Question 36

Why may breathing have evolved?

Answer 36

To enable control of breathing during running or swimming

Question 37

What does the two tube vocal tract do?

Answer 37

Allows you produce a full range of vowels that compose human speech

Question 38

Do apes have a pharynx?

Answer 38

No, so they are limited in the range of sounds that they can produce so can't provide human speech sounds

Question 39

Why did the human larynx descend?

Answer 39

To enable speech

Question 40

What is the size exaggeration hypothesis?

Answer 40

Some species that don't have speech and language, still have a lower larynx but this is because of their lower formants - sound bigger, scale other males, have a sexual selection the descent of the larynx in human could be analogies to the descent in red deer, it could have served a sexually selected function and later exalted to help human speech

Question 41

Could neanderthal speak?

Answer 41

The larynx was probably descended but his oral cavity was so long that the larynx would have had to be located in the thoracic cavity in order for its vocal tract to be composed of two tubes of equal length - could probably speak, but had a limited range of sounds - couldn't produce i and a

Question 42

Did gestural communication predate speech?

Answer 42

Gesture is predominant in primates apes perform dyadic gestural interactions but very few dyadic vocal interactions - language trained apes are better at sign language then speech

Question 43

What happened as they stood up 5-6 million years ago?

Answer 43

They stopped using hands for walking, so their hands and arms were freed, enabling more effective gesturing

Question 44

What are complex gestures associated with?

Answer 44

Food manipulation aimed throwing tool making and use

Question 45

Why are we right handed?

Answer 45

We are the only species that are right handed - dominance of left hemisphere most vertebrates show left hemisphere dominance for vocal production and perception but no left hemisphere dance for gestures in non humans

Question 46

Why has right handedness arisen?

Answer 46

Because of a long lasting association between gestures and vocalisations during he evolution of language

Question 47

What has gestural communication played a role in?

Answer 47

The evolution of speech the discovery of mirror neurons supports the idea that imitation ability essential to language may have involved gestural communication before vocal

Question 48

When were vocalisations added to communication?

Answer 48

Accompanying gesture

Question 49

What did the first spoken words come from?

Answer 49

ding dong theory - imitation of nature sounds | pooh-pooh theory - imitation of internal states bow-wow theory - imitation of other species calls

Question 50

When did vocal communication become more important?

Answer 50

When the vocal apparatus and control became more sophisticated

Question 51

What advantages does speech have over gestures?

Answer 51

Frees the hands - can do something else Works in the dark Not directional - talk to someone behind you High information flow

Question 52

When was speech discovered?

Answer 52

50,000 years ago and is culturally transmitted

Question 53

Why couldn't they speak 160,000 years ago?

Answer 53

They may have been biologically ready for speech with a modern brain and vocal apparatus but a fully efficient speech may only have been invited 50,000 yeas ago

Question 54

What is protolanguage?

Answer 54

Ability to form representations and form them into short sentences

Question 55

A possible scenario for language evolution

Answer 55

Lifestyle and tools of early humans - no more than a protolanguage consisting of mainly gestures homohabilis - good vocal control led to inclusion of vocal components homosapiens - once a modern brain and vocal tract, speech became more efficient