My dissertation

1

Actions speak louder than words?
Examining the Evidence for a gestural
genesis of human language.

Student
ID:
200604286

Supervisor:
Dr.
Diane
Nelson

Ling
3200
–
Linguistics
Dissertation

Word
Count:
11,067

The
University
of
Leeds,
29th
April
2015

2

Abstract

The prevailing theory in language emergence is that it developed vocally, either in a
continuous fashion from the calls of early primates, or discontinuously as the result of
a tremendous genetic occurrence that endowed our forefathers with the gift of
language. However, in this dissertation I examine an alternative, and I believe more
plausible, possibility that language emerged first from a system of gestures. Using
evidence from a combination of primate studies, neurolinguistics, child language and
sign languages, I form a picture of language evolution that builds upon the cognitive
and linguistic capacities of extant ape species, the capacities of which are assumed to
have been present in the last common ancestor of humans and apes. This begins with
early bipedal hominids using their now freed hands to use iconic gestures to shape
and describe the world around them, leading to a proto-‐language-‐like capacity based
on manual gestures, before speech assumed dominance perhaps as late as the
emergence of Homo sapiens and the ‘human revolution’ 35,000-‐100,000 years ago.

3

Table of Contents
LIST
OF
FIGURES
..............................................................................................................................
4

1.
INTRODUCTION
...........................................................................................................................
5

2.
PRIMATE
STUDIES
......................................................................................................................
8

2.1
VOCAL
CONTROL
VS.
MANUAL
CONTROL
..............................................................................................
8

2.2
PAN
...............................................................................................................................................................
9

2.3
PRIMATE
LANGUAGE
EXPERIMENTS
....................................................................................................
12

2.3.1
Washoe
the
Signing
Chimpanzee
.............................................................................................
12

2.3.2
Kanzi’s
Keyboard
............................................................................................................................
13

2.3.3
A
Critical
Period
for
Ape
Language?
......................................................................................
14

3.
THE
BRAIN
..................................................................................................................................
15

3.1
MIRROR
NEURONS
AND
BROCA’S
AREA
..............................................................................................
15

3.1.1
Reflections
on
Mirror
Neurons
and
Theory
of
Mind
........................................................
17

3.2
THE
MOTOR
THEORY
OF
SPEECH
PERCEPTION
.................................................................................
18

3.3
BIPEDALISM
AND
BRAIN
GROWTH
.......................................................................................................
19

3.4
ADAPTATIONS
FOR
SPEECH
–
A
MODERN
PHENOMENON?
.............................................................
20

3.4.1
Changes
to
Anatomy
–
Speech
Came
Later
.........................................................................
20

3.4.2
The
Hypoglossal
Canal,
Articulation
and
Breathing
Control
......................................
22

3.4.3
FOXP2
...................................................................................................................................................
22

4.
SIGN
LANGUAGE
........................................................................................................................
23

4.1
LATERALISATION
OF
LANGUAGE
AND
HANDEDNESS
........................................................................
24

4.2
CHILD
LANGUAGE
.....................................................................................................................................
25

4.2.1
Manual
Babbling
.............................................................................................................................
26

4.2.2
Children’s
Gestures
.........................................................................................................................
26

4.3
NOVEL
SIGN
LANGUAGES
........................................................................................................................
27

4.3.1
Homesign
in
Deaf
Children
.........................................................................................................
28

4.3.2
Nicaraguan
Sign
Language,
(LSN)
and
Idioma
de
Signos
Nicaragünese
(ISN)
..
29

4.3.3
Al-‐Sayyid
Bedouin
Sign
Language
(ABSL)
...........................................................................
30

4.3.4
Creating
a
New
Communication
System
from
Scratch
..................................................
31

5.
BUT
WHY
THE
SWITCH
TO
SPEECH?
..................................................................................
34

6.
CONCLUSION
..............................................................................................................................
36

7.
REFERENCES
...............................................................................................................................
38

4

List
of
Figures

Fig.
1
Phylogenetic
tree
of
extant
great
ape
species………………………………………………….9

Fig.
2
Flexibility
of
different
communication
types
in
chimpanzees
and
bonobos….…11

Fig.
3
A
comparison
of
the
macaque
and
human
cerebral
cortex…………………………….16

Fig.
4
Brain
size
comparison
of
extant
primates
and
other
species………………………….20

Fig.
5
Comparing
the
human
and
chimpanzee
vocal
tract………………..……………………..21

Fig.
6
Frequency
of
interaction
type
in
chimpanzees
and
bonobos…………………………..32

Fig.
7
Success
of
different
gesture
types
judged
by
identification
accuracy……………..32

5

1.
Introduction

Ever since scientists and thinkers began to doubt the traditional, religious stance on
language as a gift from God, scattered from the mythical Tower of Babel to form the
world’s myriad tongues, language’s origin has enthralled and perplexed generations.
Among them are proponents of the gesture-‐first theory, who have put forward the
idea in various guises since John Bulwer’s ‘The Natural Language of the Hand’ (1644),
before Cordemoy (1668/1972:3) called gestures ‘the most natural way to express our
thoughts... also the first of all the languages,’ citing its ubiquitous understanding
across countries and cultures as a reason for its feasibility. The 18th
century
philosopher Giambattista Vico (1953/1744) imagined an original system of mimetic
gestures which represented images of the imagination, before de Condillac
(1971/1746) proposed a similar idea demonstrated by a fable of two strangers
communicating by sign alone. The 19th
century saw Darwin haltingly acknowledge
that language in its original form was perhaps ‘aided by signs and gestures’ (Darwin,
1871:86). However, this speculation was not well received by bodies in both France
and England. The Linguistics Society of Paris, founded in 1865, banned from the
outset all debates that focused on the origin of language, and in 1873 the President of
the Philological Society admonished: ‘We shall do more by tracing the development of
one work-‐a-‐day tongue, than by filling waste-‐paper baskets by reams of paper
covered with speculations on the origins of all tongues.’ (McNeill, 2005:11).
Despite its troubled beginnings, the gestural theory picked up speed in the
20th
century with the publication of Gordon Hewes’ ‘Primate Communication and the
Gestural Origin of Language’ (1973) in which he sets forth his argument with evidence
from recently conducted primate language experiments. Using more modern
technology, Rizzolatti et al (1998) published a paper describing the presence and
importance of mirror neurons in certain areas of the brain. Their hypothesis provides
support for the gestural origin theory as it evidences a strong relationship between
action of the arm and mouth in non-‐human primates, as well as a crucial role in
seeing and mimicking the actions of others (to be discussed in more detail in 3.1). This
paved the way for other linguists to further examine its merit, notably Corballis (2002,

6

2003, 2012), Armstrong & Wilcox (1995, 2007), Pollick & de Waal (2007) and
Tomasello (2008).
Proponents of the vocal theory argue that language evolved not from signs
but from a system evolved in the auditory-‐vocal modality (Dunbar 1996; Deacon
1997; Fitch 2000; Knight 2008). The literature on the speech-‐first argument focuses
on either a discontinuous view that language arose suddenly and in a near-‐perfect
form, perhaps by the appearance of a new gene (FOXP2) coinciding with the ‘human
revolution’ some 40,000 years ago (Chomsky, 1996, 2004; Lenneberg, 1967), or by a
continuous evolutionary process in a similar way to other adapted-‐for traits (Pinker
and Bloom, 1990).
New evidence collected over the past few decades bolsters the argument that
the speech-‐first scenario is inferior: the FOXP2 gene has recently been shown to have
existed in Neanderthals and has also been seen to influence both language processing
and motor sequencing ability, including finger movements (Peter et al, 2011), giving
compelling evidence that this gene may have had an influence in a gestural precursor
to language. The idea that language arose fully formed is also flawed. As Kirby
(2007:674) argues, ‘this is only really plausible if language isn’t as complex as it
appears. The appearance of eyes fully formed in evolution in one step is implausible
precisely because the eye is a complex organ’. Furthermore those who suggest that
language could have evolved from the vocal calls of non-‐human primates (Aiello &
Dunbar, 1993; Dunbar, 1996; Zuberbühler, 2005) do not account for the fact that
these vocalisations are inflexible and cannot be broken down or combined into
sequences, and that these calls are primarily instinctive and emotionally-‐driven:

‘production of sound in the absence of the appropriate emotional state seems to be
an almost impossible task for a chimpanzee’ notes eminent primatologist Jane
Goodall (1986:125). Despite a recent study of putty-‐nosed monkeys that claimed they
combine sounds to encode slightly different meanings, the compositional, recursive
power of human language was still lacking (Arnold & Zuberbühler 2006). However,
this basic combinatorial ability that seems to be present in these primates could signal
a rudimentary precursor to a complex aptitude for syntax that may well have been
present in the last common ancestor (‘LCA’ hereafter) (Fay et al, 2014; Cheney &
Seyfarth, 2005). A final objection to the theory is that if gesture was the first way in

7

which language was used, then why do we now exclusively use speech to
communicate? MacNeilage suggests that a gestural system ‘would have proved so
indispensable that we would never have abandoned it’ (2011: 434), however there
are several advantages that signed languages provide, as well as other reasons as to
why a switch to a vocal modality could have occurred.
Instinctively, the iconic nature of the majority of signs lends itself better to the
earliest form of language; by describing the world around them iconically and
mimetically, our early bipedal ancestors gained the ability to transfer meaning from
one member of the group to another without the use of speech. As Stokoe (2001:xii)
puts it, ‘who could possibly have told the first speakers what the sounds they
produced were supposed to mean[?]’. He argues that the earliest communicative
system was based on gestures, where hand shapes represented aspects of the visual
world around our early ancestors: people, places, things, and the movements of the
hands represented actions and changes, and that these were the earliest form of
sentences: ‘The key to this development is that only gesture use could have initiated
syntax, a necessary feature of language.’ (2001:xiii)
In order to examine the support for the gestural theory of language evolution,
it is useful to turn to Bickerton’s three aspects of linguistic behaviour that he terms
‘living fossils’ (1990:105; 1995) of an earlier protolanguage. These consist of (i) the
Language of Trained Apes, (ii) Child Language and (iii) Pidgin Communication.
Although Bickerton is a speech-‐first advocate, he comments that ‘what form of signal
was first used is relatively unimportant’ (1990:156), and adapting his model to
examine the viability of the gestural equivalents instead of speech in language
evolution can provide clues to how language may have emerged gesturally. Since
evidence for the gesture theory has broadly been taken from a combination of
primate language studies, analysis of child language development and aspects of
pidgin sign language (such as Nicaraguan Sign Language), Bickerton’s model applies
perfectly to a gestural protolanguage. This evidence, combined with an examination
of language in the brain -‐ including the action of mirror neurons-‐ will be the focus of
this dissertation; the strength of each of these lines of inquiry will be evaluated in an
attempt to answer the question: did language emerge gesturally in our ancestors?

8

2.
Primate
Studies

Since no animal in the wild has ever acquired the command of anything approaching
human language, it could seem unlikely to turn to this source of evidence to attempt
to explain it. However some linguists argue that by examining the abilities and
shortcomings of primate communication, the capabilities of the LCA can be
elucidated (Rizolatti & Arbib, 1998). This means it is possible to track the
development of traits necessary for fully articulate language through the Homo line
that were not present in our cousins’ lineage over the last ~8 million years of
evolution (Pinker, 2003).
2.1 Vocal Control vs. Manual Control

Theories in support of the gesture-‐first argument have focused on the inability of
apes to control their vocalisations, compared to the ‘excellent cortical control over
the hands and arms’ (Corballis, 2009:22) that nonhuman primates demonstrate. In
primates, vocalisations lack the range and combinatorial power of human speech, and
are controlled by the limbic system, an ancient area of the brain associated with
emotion, and are not under the voluntary control of the motor cortex (Ploog 2002;
Fogassi & Ferrari, 2007). These primate vocalisations are primarily a reaction to a
specific emotion or need, such as fear, hunger or sexual desire (Deacon, 1997), and
have their evolutionary human counterparts in primal sounds like moaning, crying
and screaming (Pinker, 1994). This is in comparison to a large range of voluntary
manual movements, which are under the control of the lateral motor cortex and are
used flexibly (Hurford, 2003; Corballis, 2009), a skill that has been utilised in primate
language experiments (Gardner & Gardner, 1969; Savage-‐Rambaugh et al, 1998).
Further, both humans and nonhuman primates are primarily visual creatures,
with sight superior to hearing in both species, perhaps an evolutionary adaptation to
visual predation. This means that they are better adapted for communication in the
visual modality than the auditory (Corballis, 2010), and thus early hominids may have
had the tools to communicate using gesture before speech.

9

2.2 Pan

Many animals in the wild commonly communicate with vocal calls, but the manual
gestures of humans and apes are considered practically unique (Maestripieri 2005;
Pollick & de Waal, 2007; Roberts et al, 2012). Hobaiter & Byrne (2014) argue that ape
gestures often have specific meanings and that captive and wild gorillas and
chimpanzees use intentional signs to serve specific functions. These flexible,
intentional gestures of the hands and limbs provide evidence of an ancestral trait
common to Homo sapiens and our great ape relatives that support the gestural
theory of language evolution (Roberts et al, 2012; Pika et al, 2005; Pollick & de Waal,
2007). The studies below demonstrate how language-‐trained, wild, and captive apes
help to elucidate the gestural theory of language evolution.

The phylogenetic tree below displays the relationship between extant great
apes and humans, and is consistent with the general estimate that the Pan line
separated from the Homo line around 5-‐7 million years ago (Kumar et al, 2005).
While all primates exhibit facial expressions and vocalisations, apes and
monkeys differ in that monkeys lack the free, ritualised hand gestures that are
present in chimpanzees and bonobos, which include begging for food with an
Figure
1.
Phylogenetic
tree
of
extant
great
ape
species

(www-‐tc.pbs.org)

10

upturned palm, impatient wrist shaking, and domineering arm movements over a
subservient conspecific (Pollick et al, 2008).
Since bonobos and chimpanzees split from the Homo line the most recently,
they are the most closely related primates to human beings and the evolutionary
ancestry we share may shed light on the kind of abilities present in the LCA of humans
and apes, and therefore on how language may have evolved in our species (Corballis,
2009). Manual gestures have become of particular interest as the neural structures
associated with them in great apes are homologous with those associated with
language in the human brain (Roberts et al, 2013) (examined further in 3). Using this
logic, Pollick and de Waal (2007) ran a study to compare the flexibility of chimpanzee
and bonobo manual gestures with orofacial movements and vocalisations. The aim of
the study was to assess how context-‐driven these were, and to what extent gestures
were more flexible than vocalisations. They observed two groups of bonobos and two
groups of chimpanzees in captive environments, all of which exhibited aspects of
gesture, broadly defined by Kendon (2004:14) as ‘movements that… manifest
deliberate expressiveness to an obvious degree’. By this he means that to qualify as a
gesture, it must be meaningful, intentional and easily discerned by the audience
(Zlatev, 2015).
Firstly they found that gestures were far more flexible than either facial or
vocal signals, in that they were less bound to being produced in a particular context.
Corballis (2009:554) asserts that ‘freedom from context is one of the characteristics
of language’, and it is with this in mind that Pollick & de Waal enacted their study:
they calculated the ‘CTI’, or Context-‐Tie Index, which was the percentage of times
that a signal was used in its most typical social context, e.g. during grooming, to
initiate sex, etc. Fig. 2 shows that the vocalisations ‘scream’ and ‘pant hoot’ had a
very high correlation across contexts, meaning that they were produced far more
commonly in their typical contexts in comparison to gestures, which did not reach a
high CTI. Strikingly, four of the gestures correlated negatively across contexts,
suggesting that they are used in vastly different contexts by both the bonobo and
chimpanzee groups (Pollick & de Waal, 2007).
This discrepancy between species acts as further evidence that human
language may have its roots in the abilities of our primate cousins; their gestures vary

11

between species just as human gestures vary across cultures as a result of cultural
transmission. In addition, human facial expressions tend to be far more universal than
culture-‐specific gestures (Kendon, 1995), and apes also tend to share facial
movements, evinced by the high CTI ‘silent bared teeth’ and ‘relaxed open mouth’
that is shared between chimps and bonobos (Fig. 2).

A comparable study conducted by Roberts et al (2012:466) garnered similar
results; they studied a wild population of chimpanzees and found that their gestures
‘are perceived semantically and manipulate the recipient’s movements and attention,
while recipients also infer the broader goal of the signaller from context.’
Overall gestures show greater contextual variation in both wild and captive
chimpanzees than facial and vocal signals, and do not necessarily need to be viewed
in a particular context to elicit a response unlike vocalisations, which are closely tied
to context. De Waal and Pollick (2012) argue that this makes gesture a likely
candidate for the modality in which symbolic meaning may have evolved in the early
hominid population.

Figure
2:
Flexibility
of
different
communication
types
in
chimpanzees
and

bonobos,
taken
from
Pollick
&
de
Waal
(2007:
8187).

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2.3 Primate Language Experiments

The language of trained apes is one of Bickerton’s (1990:105) ‘living fossils’, aspects of
language that share some -‐ but not all-‐ of the characteristics of modern human
language. Tallerman argues that language trained apes such as those described below
likely show ‘the type of cognition early hominins brought to protolanguage’ (2011:
489), and thus can illuminate the aspects of cognition that were built upon to develop
language.
2.3.1
Washoe
the
Signing
Chimpanzee

There have been many attempts to teach primates language that have largely focused
on our closest relatives, chimps and bonobos (Gardner & Gardner 1969; Savage-‐
Rumbaugh et al, 1998). These experiments have shown that nonhuman primates
have no ability to speak whatsoever, having been inhibited by the shape of their vocal
tract -‐ the larynx is descended in humans, and the greater flexibility of our tongue
allows us to produce a larger array of sounds (Gillespie-‐Lynch et al, 2014). Voluntary
cortical command over their vocalisations is also limited, and is controlled largely by
the ‘cingulate system’, an area deep in the brain associated with emotion that is not
homologous with language areas (Vilain et al, 2011). Tellingly, attempts to teach
primates signed language have been far more successful.
Washoe the chimpanzee was adopted by the Gardners at ten months and was
raised by them as though she were a human child. She was taught a variety of signs in
simple ASL (American Sign Language) through imitation as well as by instruction. She
achieved a degree of proficiency in ASL beyond any vocal ability that was
demonstrated (Gardner & Gardner, 1969), and after 8 years had a repertoire of over
150 signs. Importantly she also displayed some ability at creating spontaneous signs,
notably combining the signs for ‘water’ and ‘bird’ when viewing a swan, as well as
‘rock berry’ for a brazil nut (Fouts, 1975; Fouts & Rigby, 1977). This kind of
spontaneous combination of gestures to create a novel sign was taken as evidence
that Washoe understood the meanings of the signs, and was not simply producing
them in response to specific stimuli.

13

Furthermore, a secondary experiment exposed Washoe’s adopted son Loulis
exclusively to the sign language of four signing chimps (including Washoe), and found
that he actively learnt the signs through teaching as well as by the moulding of his
hands to the correct configuration (Fouts et al, 1989). This mirrors the mother-‐child
interaction, imitation and pedagogy prerequisite in human language acquisition.
2.3.2
Kanzi’s
Keyboard

Kanzi is considered the most accomplished of all the language-‐trained apes (Savage-‐
Rumbaugh et al, 1998; Corballis, 2012a) and communicates by pointing to a keyboard
with a range of lexigrams, as well as with some ASL. He was present while the
researchers attempted to teach his mother to use the lexical board to no success, and
acquired the ability spontaneously without implicit teaching or rewards (Savage-‐
Rumbaugh et al, 1986). Kanzi used the keyboard to string together combinations of
two or three symbols to create simple phrases, as well as inventing his own gestures
to add to his repertoire when he outstripped the 300 symbols available to him on the
lexical board. The keyboard required fine control to operate, and he also combined
pointing with other gestures to elucidate meaning. The combinations he put together
showed some capacity for English word order, as well as basic ability to assign
grammatical rules (Greenfield & Savage-‐Rumbaugh, 1990).
Strikingly, Kanzi’s ability to perceive human speech was more developed than
his production, and he frequently acted on complex, novel sentences even when the
requests were unusual or counterintuitive. For example, using toy equivalents he
correctly performed ‘make the doggie bite the snake’, as well as completing the task
with the animals’ roles reversed (Savage-‐Rumbaugh et al, 1993: 96). His
comprehension was compared to that of Alia, a human child at a similar age of
linguistic development, and was found to outstrip hers when tested on a variety of
sentence types. Kanzi responded correctly on 74% of occasions compared to Alia’s
65% (Savage-‐Rumbaugh et al, 1993:76). While Savage-‐Rumbaugh argues that ‘more
than any previous ape, the nature and the scope of Kanzi's language acquisition has
paralleled that of the human child’ (1993: 12). This is not to say that Kanzi displayed
human levels of intelligence, or even an extraordinary aptitude for human language.
His production was limited to simple phrases and requests, and showed little of the

14

boundless expression that children express a little later in their development. Further,
96% of his ‘utterances’ were requests, a far larger percentage than would be normal
for a human child. Towards the end of the study Alia’s production and comprehension
leapt far beyond Kanzi’s (1993:567). This suggests that Kanzi’s abilities, although
impressive, are limited, and they resemble a large lexicon coupled with a very basic
‘proto-‐grammar’ that is not akin to human language (Pinker, 1994; Tallerman, 2011;
Fitch, 2010, who argues that this is no more than word order) and a good perception
of complex strings of lexical items. However there is little evidence to suggest that he
truly understands the more complex grammar that he hears. Tallerman (2011: 453)
provides the example ‘Go get the balloon that’s in the microwave’-‐ and argues that
there is no way of telling that Kanzi understands the relative clause and is instead
acting on the basic lexical items in the phrase ‘get – balloon – microwave’, and infers
the rest from context. This type of processing, a kind of telegraphic connecting of
gestures with basic understanding of objects and actions without complex grammar
in the manual mode, seems the most likely candidate to have been a precursor for
language in the LCA and early hominids.
2.3.3
A
Critical
Period
for
Ape
Language?

A largely under-‐addressed finding from the study was that of the nine apes that were
reared together, those who were not exposed to language until after the age of 2½
did not acquire the use of signs without prolonged, explicit language training
(Rumbaugh, 1977; Savage-‐Rumbaugh et al, 1993). Their comprehension too was
greatly diminished, and by 9 years of age the late-‐exposed apes only understood a
few words compared to the early-‐exposed chimps that all understood at least 40
different spoken words by 2½ years. The fact that humans also have a critical window
for language acquisition (Penfield & Roberts, 1959; Lenneberg, 1967) strengthens the
gesture-‐first argument in that humans and apes share similar neural traits, such as
brain plasticity in language learning, which may therefore have been present in the
LCA. It also weakens the musical protolanguage theory (Mithen, 2011), as human
song transmission has no such critical period (Tallerman, 2007).
While these attempts at teaching and monitoring apes’ language have been
somewhat successful, their actual language ability has barely progressed past the

15

capability of a 2½-‐year-‐old girl. There is no doubt that apes can assign meaning to a
sign in hundreds of pairs (Fitch 2010), but the real merit in these studies is that they
show that the more likely scenario for language emergence is that it was based on a
system of manual gestures rather than vocalisations. They demonstrate an ability to
assign a symbol to a real-‐world referent in the manual domain, as well as a capacity
for a ‘proto-‐grammar’ (Greenfield & Savage-‐Rumbaugh, 1990: 572) in the perception
of basic syntax. Further, they show that ape gestures are susceptible to both social
learning and the attentional state of the recipient, which are both prerequisites for
language (Corballis, 2009). ‘Communicative capacities observed across members of a
clade (sibling species with a common ancestor, such as humans, chimpanzees, and
bonobos) are likely inherited from a common ancestor’ (Gillespie-‐Lynch et al, 2014:2).
Hence, these abilities are likely to be present in the LCA and our hominin ancestors
were likely to have been better preadapted for control of limbs and hand movements
than for vocal control. This was shown by the success of our great ape relatives in
types of sign language learning, as well as the greater flexibility of gesture in
communication than vocal calls.
3.
The
Brain

I have described the likely cognitive and linguistic capabilities of our hominid
ancestors, as well as the similarities and differences between the Homo and Pan
branch of the Hominidae. The following is an examination of the brain’s role in
language and its evolution, and specifically how the visuo-‐manual modality was
crucial in the emergence and evolution of language. By studying both the human and
nonhuman primate brain in tandem, as well as the varying brain structures and
capacities of modern and ancient humans, a picture of how gesture could have been
the origin of language is elucidated.
3.1 Mirror Neurons and Broca’s Area

At the simplest level, in order for language to evolve it is crucial that a sender and
receiver of a message are both able to produce and perceive a signal. Rizzolatti &
Craighero (2004:183) argue that mirror neurons are central in the development of

16

this ability: ‘Mirror neurons represent the neural basis of a mechanism that creates a
direct link between the sender of a message and its receiver…actions done by other
individuals become messages that are understood by an observer without any
cognitive mediation.’ Thus, mirror neurons have provided a fresh perspective on the
gesture theory. First observed in macaques (Rizzolatti et al, 1998), and further
elaborated in the discovery of a mirror system (Arbib, 2005a; Rizzolatti & Sinigaglia,
2008), these are motor neurons that fire both when an animal performs an action as
well as when it is observed.
Although mirror neurons cannot be observed directly in the human brain
(Corballis, 2010), imaging has revealed a mirror-‐neuron system in humans that also
activates when actions are imitated, that is not present in monkeys (Rizzolatti,
Fogassi, & Gallese, 2001, Rizzolatti & Craighero, 2004). This has implications for the
evolution of language in that the ability to actively mimic another’s action would have
been pivotal in learning and propagating an emerging gestural system.
Further, the mirror neurons were found in an area of the macaque brain that
is homologous with Broca’s area in humans, the area traditionally associated with
language production (Fig. 3) (Broca, 1861; Fogassi and Ferrari, 2007). While Broca’s
area has traditionally been associated with the production of speech, it is also
involved in motor tasks such as complex finger and hand movements, sensorimotor
learning and imitating hand shapes (Rizzolatti & Craighero, 2004). This same
activation is also observed when people imagine themselves making these
movements (Gerardin et al, 2000). This suggests a link between the production of
Figure
3:
A
comparison
of
the
macaque
(A)
and
human
(B)
cerebral
cortex.
Yellow
areas
in
both
are
the

primary
motor
cortex,
orange
the
premotor
cortex.
The
red
areas
indicate
the
hypothesised
homologue

cortical
motor
areas
that
relate
to
communication
and
language,
F5
in
the
monkey,
and
areas
44
in
the

human,
also
known
Broca’s
area.
Taken
from
Fogassi
&
Ferrari
(2007:2)

17

language and motor movements of the hands and limbs which is strengthened by the
finding that signed language also activates Broca’s area (Horwitz et al, 2003).
The human mirror system differs from the monkey mirror neuron system in
certain aspects: for example while monkey mirror neurons do not fire in the absence
of a goal-‐less grasp, these ‘intransitive meaningless movements’ do excite a response
in the human mirror system (Rizzolatti & Craighero, 2004:176). Corballis (2012b)
argues that in this case, an early language system incorporated symbolic actions and
representations and not simply objects in the here-‐and-‐now. He argues that this
system may therefore have been involved in the critical step in the development of
language from a capacity of simple communication to one in which our ancestors
were capable of ‘mental time travel’, the ability to express events in a separate time
and space from the present which Corballis & Suddendorf (2007:310) view as a
prerequisite for, and uniquely human aspect of, language.
Corballis (2012b:109) does not downplay the importance of mirror system in
humans: ‘in the course of evolution, the system initially specialised for grasping
provided the basis for the subsequent emergence of an intentional communication
system based on manual gestures’. This view appears to be the most likely based on
the evidence from mirror neurons in both monkeys and humans, where the system
that allowed imitation was developed to allow mimesis and a basic gestural
communicative system.
3.1.1
Reflections
on
Mirror
Neurons
and
Theory
of
Mind

Since the mirror system ‘gives the observer a first-‐person understanding of…the goals
and intentions of other individuals’ (Rizzolatti & Sinigaglia, 2010:264), mirror neurons
have also been cited as important in the development of ‘theory of mind’, a critical
prerequisite for co-‐operative behaviour and language (Gallese & Goldman, 1998).
Theory of mind is the ability to empathise with another individual and to
realise that they have knowledge and perspectives that are different to one’s own
(Premack & Woodruff, 1978). It has been cited as a uniquely human ability (Penn et
al, 2008), is inextricably linked to the language faculty (Malle, 2002), and has been
described as a precondition for the acquisition of language (Origgi & Sperber, 2000).

18

Autistic children, whose social disability is characterised by a lack of empathy
and extreme difficulty in language learning (Carpenter & Tomasello, 2000), have been
suggested to lack full theory of mind (Baron-‐Cohen et al, 1985). Some suggest that a
dysfunction in the mirror system is responsible for this deficiency, and in turn this
affects the ability to acquire language (Williams et al, 2001). Further, those with
autism consistently produce fewer gestures, and these are developmentally less
advanced than those without autism (Buitelaar et al, 1991; Mundy et al, 1986). They
also show difficulty imitating the body movements of others (Williams et al, 2004) and
have a host of motor deficits (Ming et al, 2007). If we accept that the mirror system,
imitation, language and gesture are all interlinked, then the autistic child provides an
example of this connection by the absence of these features.
It is worth noting that theory of mind may well have been a later addition to
language, as it is not found in apes (controversially, Call & Tomasello, 2008). The
earliest language would not have necessarily involved taking into account another’s
mind; when simply referring in iconic expressions, this may simply have influenced
behaviour in another individual without the demonstration of joint attention (Malle,
2002) before developing into a more sophisticated form in which gestures were
mutually made and understood.
3.2 The Motor Theory of Speech Perception

Corballis takes the motor theory of speech perception, first posited by Liberman et al
(1967) as evidence that language was originally based on a system of gestures. The
motor theory posits that humans comprehend speech based primarily on articulatory
gestures of the vocal apparatus rather than an acoustic signal. Corballis therefore
argues that ‘the shift (between speech and sign language) is not so much from vision
to audition as from one kind of gesture to another’ (2009:24). He links this to the
mirror system in humans, and asserts that articulations are simply vocal gestures. I
find this argument largely unconvincing however, and it seems more likely that
speech may have emerged as the result of the ‘expanding spiral’ that Arbib
(2005b:22) describes. He argues that H. Habilis through to H. sapiens communicated
via a gestural protolanguage, which provided the neurological scaffolding for the
emergence of a spoken protolanguage. These two systems then developed

19

simultaneously in the hominid line in an ‘expanding spiral’ that led to a relatively
complex gestural language before the emergence of proto-‐speech. This, along with
other possibilities, is discussed in greater detail later in section 5.
3.3 Bipedalism and Brain Growth

Many argue that bipedalism was a crucial factor in the emergence of human language
(Corballis, 2002; Gillespie-‐Lynch et al, 2014). Although it is difficult to date precisely
when our ancestors began to walk upright, fossil and genetic evidence place the date
at around 5-‐7 million years ago (Rosenberg & Trevathan, 2014). This had tremendous
implications for the evolution of our species: walking upright freed the hands for the
later emergence of tool use, as well as having implications for speech as the larynx
descended to a position where vocal control was possible, but perhaps only with the
emergence of Homo sapiens (Corballis, 2002). As the feet became less functional than
in our chimpanzee relatives, the neural space for control of the feet diminished in the
Homo line and allowed neural reorganisation for greater control of the hands.
Further, it has been shown that control of the hands is experience-‐led, so the more
the hands are used, the greater neural space is dedicated to them in comparison to
the feet (Richards, 1986; Corballis, 2002). Donald (1991:162) argues that later
obligate bipedalism in the Homo genus, with an arboreal lifestyle no longer necessary,
would have freed the hands and arms for a variety of uses including intentional
communication and ‘mimetic culture’. This is differentiated from the mimicry that
some animals possess (e.g. parrots) and imitation, somewhat limited to apes, in that it
is not literal, and involves ‘the invention of intentional representations’ (1991:169)
that are creative and novel. Corballis adds that a feature of gestural communication
allowed by bipedalism was the ability to ‘move in four dimensions’ (2009:32), allowing
mimetic displays of actual events using the hands which can incorporate a dimension
of time, a feature of mental time travel mentioned previously.
Bipedalism marks the split of the Homo line from the line of the nonhuman
primates, and was accompanied by a growth of the brain (Corbalils 2002). Although it
took roughly 4 million years from the earliest onset of bipedalism to a marked
increase in brain size in the hominid line (Nelson, 2009), it is possible that early

20

hominids such as Homo habilis had the capacity for a protolanguage based on manual
gestures in part due to a significantly larger brain size in all subsequent species of
Homo than in chimpanzees and other extant apes (Fig. 4). This is strengthened by the
discovery of enlarged Broca’s and Wernicke’s areas in endcocasts of Homo habilis
skulls (Tobias, 1998), which may indicate that this species had some semblance of
language, likely a system of gestures.

3.4 Adaptations for Speech – A Modern Phenomenon?

It has been inferred that articulate speech would not have been possible until
relatively late in the hominid lineage, due to the extensive changes to the vocal tract
and neurological control of vocalisation and breathing that may not have been
complete until the emergence of Homo sapiens ~170,000 years ago (Lieberman 1998;
Stokoe, 2001).
3.4.1
Changes
to
Anatomy
–
Speech
Came
Later

The vocal tract of chimpanzees is incredibly limited in comparison to modern humans;
while humans can articulate a vast array of speech sounds, chimpanzees are limited
to a small repertoire of phonemes that is infinitely less flexible than in human speech
(Lieberman, 1975). This is due to the shape of the tongue and larynx (fig.5).
Figure
4:
Comparison
of
brain
size
in
extant
primates
and
other
species,
taken
from
Corballis
(2002:89).

21

The descent of the larynx depicted in fig.5 played a pivotal role in the
evolution of human speech; some suggest that this was kick-‐started by the advent of
bipedalism (DuBrul, 1976), but this remains controversial (Fitch, 2000). Nevertheless,
the new shape of the larynx made it possible to move the tongue both vertically and
horizontally inside the mouth, altering the shape of the vocal tract sufficiently to
produce a wide array of vowels and consonants pivotal to human speech that are
unavailable to chimpanzees. This descent is also found in the growth of infants to
children to adults; while still suckling the baby is capable of breathing and ingesting
liquid simultaneously, a capacity shared by apes (Fitch, 2000), before descending
when it reaches age 3 or 4 (Sasaki et al, 1977). This is a costly transformation as it
makes humans more susceptible to choking due to the convergence of respiratory
and digestive pathways, but some suggest that this was a worthwhile evolutionary
price to pay when the result is speech (Van Driem, 2005).
Fossil records have proven inconclusive in attempting to show that this
descent was also complete in Neanderthals (Fitch, 2000), but from the evidence
available it seems plausible that the position of the larynx and hyoid bone in
Neanderthals led to a basic phonetic ability, more complex than other primates but
less complex than in modern Homo sapiens (Crelin, 1987). Lieberman (1998) argues
that the adjustments necessary for vocal language were not complete in
Neanderthals, perhaps as recently as 30,000 years ago, due to the absence of a
Figure
5:
Vocal
tracts
of
chimpanzees
(b)
and
humans
(c).
Red=
Tongue
body,
Yellow=

Larynx,
Blue=
Air
sacs
(distinct
to
apes).
Taken
from
Fitch
(2000:260).

22

flattened, human like-‐face to restrict the length of the vocal tract, which in humans
makes it possible to produce fluent speech. Since Neanderthal remains show signs of
tool making and cultural practices, it is safe to assume that they were neurologically
capable of a co-‐operative form of protolanguage, and because they were unable to
produce the fluent speech present in Homo sapiens, but retain the manual ability of
their and our ancestors, this was more likely to be a system reliant on gestures
(Nelson, 2009).
3.4.2
The
Hypoglossal
Canal,
Articulation
and
Breathing
Control

The nerves that allow articulations of the tongue pass through the hypoglossal canal,
located at the base of the skull. These allow the fine control necessary for human
speech (Kay et al, 1998). It has been found that the hypoglossal canals of
Australopithecus as well as Homo habilis are similar in size to extant Pan species, and
are significantly smaller than those present in modern and ancient Homo sapiens (Kay
et al, 1998). This suggests that the vocal abilities of ancient hominids were not as
developed as modern humans, or indeed of Neanderthals, who also had enlarged
canals, although this may have been the result of an overall larger stature in general.
Additionally, evidence from Maclarnon & Hewitt (1999) has shown that breathing
control, essential for the production of fluent speech, would not have been fully
evolved until around 1.6 million to 100,000 years ago. This was surmised from an
examination of the fossilised thoracic vertebral canal, which carries nerves that
innervate the muscles involved in and around the thorax, allowing for voluntary
breath control. A human-‐like appearance was not present in Australopithecines,
Homo ergaster, or early Homo erectus, whose thoracic canals were similar in size and
structure to extant ape species.
3.4.3
FOXP2

The FOXP2 gene has largely been referred to as ‘the language gene’ by the media
(BBC News, 2009), after it was discovered that a mutation of the gene in many
members of a family led to severe language impairments. This reductive labelling
reduces the complexity of the gene’s role in language: more specifically the disruption
of the gene causes non-‐activation in Broca’s area during verb generation and difficulty

23

in coordinating orofacial movements, leading to atypical speech delivery (Lai et al,
2001; Watkins et al, 2002; Liégois et al, 2003). The import of these finding is twofold;
FOXP2 is clearly involved in both the articulation of speech as well as the function of
Broca’s area, both critical for the delivery of speech. The FOXP2 gene has undergone
two mutations since the split between hominids and chimpanzees (Corballis, 2009),
and while the gene has supposedly been detected in a 45,000 year old Neanderthal
fossil, which in turn suggests it may date back 700,000 years (Krause et al. 2007;
Noonan et al. 2006), this finding has been criticised by Coop et al. (2008) who claim
that this was more likely due to contaminated samples or the result of interbreeding
between Neanderthals and Homo sapiens. As previously discussed, Neanderthals are
unlikely to have possessed the ability to speak anyway. Nevertheless, if this particular
variant of gene has emerged relatively recently in the hominid line, most estimates
range between 38,000 to 200,000 years ago (Enard et al, 2002; Pinker, 2003), this
may have coincided with the emergence of Homo sapiens. Corballis (2004:96) argues
that ‘it is possible that mutation of FOXP2 was the most recent event in the
incorporation of vocalization into the mirror system, and thus the refinement of vocal
control to the point that it could carry the primary burden of language’. The
emergence of FOXP2 therefore may have been the crucial factor for linking gesture to
speech: Broca’s area, a crucial seat of the mirror system, may have been adapted by
the mutation of FOXP2 to allow articulatory control of vocalisations in Homo sapiens
after a gestural system had already been in place previously.
Therefore it seems likely that while hominids had developed the cognitive
capacity to use a form of protolanguage, to manipulate their limbs, to use symbols
and mimesis, their vocal and breathing apparatus were ill-‐equipped to serve an
articulate speech system until the emergence of Homo sapiens who possessed
greater control of their vocalisations and breathing, as well as a proclivity for speech
due to the emergence of the FOXP2 gene.
4.
Sign
Language

So far I have focused on cognitive preadaptations for a gestural language, and now I
turn to evidence from the utility and naturalness of sign, as well as from the

24

formation of novel signed languages. This can shed light on how a gestural system
could have arisen in early humans, against the argument of a vocal language origin.
While it was previously thought that ‘the manual sign language must be viewed as
inferior to the verbal as a language’ (Myklebust 1957:242), it has since been proved
that sign languages are full languages, capable of all the syntactic and abstract
complexity present in speech (Stokoe, 1960). Modern day vestiges of an ancient
gestural system can still be observed: we gesticulate as we speak, all cultures use
gestures in their repertoire, children gesture before they can speak and even
congenitally blind children use both iconic and deictic gestures without ever seeing or
having the chance to copy them (Acredolo & Goodwyn, 1988). This led Iverson &
Goldin-‐Meadow (1997:466) to suggest that gesture plays ‘a role for the speaker that
is independent of its role for the listener’. In addition, spoken and signed languages,
despite the differences in input, i.e. the auditory versus the visual, are processed in
the same areas of the brain and the systems that support them are near identical
(MacSweeney et al, 2008). All this suggests that the capacity for signs and gestures to
communicate meaning is inbuilt, natural and integral to language function. Below I
examine the form, function and defining features of various types of languages
characterised by their use of gesture, from the pre-‐verbal stage in children to
spontaneous languages created by adults to show how these contribute to the
discussion of the gestural theory of language emergence.
4.1 Lateralisation of Language and Handedness

Language in the brain is lateralised mainly in the left hemisphere, a finding initially
posited by Paul Broca when he observed that damage to the left hemisphere causes
aphasia but damage to the right does not (Broca, 1861). Recent studies have
confirmed this bias (Knecht et al, 2000), which in turn provides insight into the
development of early language. The population-‐level bias of right handedness and
left-‐hemisphere language dominance are intimately connected, and it has been
suggested that this is due to an original right-‐handed manual dominance which in
turn developed the left side of the brain in language evolution (Corballis, 2012b;
McManus, 2002).

25

Since language is lateralised in the left hemisphere of the brain in more than
90% of right-‐handers (Tzourio-‐Mazoyer & Courtin, 2013) and around 88-‐90% of the
population have this handedness preference (Corballis, 2012b:115), it is suggested
that the two are intricately correlated. This is an ancient characteristic, as right-‐
handed dominance has been observed in early hominids from at least 1.5-‐1.6 million
years ago based on skeletal fossil evidence and observation of crafted tools (Walker
and Leakey, 1993). The fact that this kind of lateralisation was present at this time
again suggests that brain specialisation for language was underway in early hominids
(Haviland et al, 2010). Similarly, in deaf sign language speakers, linguistic signs are
made with the dominant hand (normally the right) while the other plays a diminished
role in communication (Brentari, 1998). Interestingly, this left-‐handed role is often
paralinguistic and emotional, typically right-‐hemisphere controlled functions
(Lausberg et al, 2007). In addition, children show a significant bias for symbolic
gestures using their right hand compared to non-‐symbolic gestures for which they
tend to use the left (Bates et al, 1986). Children’s hand preference in signing precedes
their use of a dominant hand in object manipulation – the hand they use for signing is
significantly correlated with the hand that eventually becomes dominant for other
activities (Bonvillian & Richards 1993). This again demonstrates that handedness,
language-‐like gestures and lateralisation of language in the left hemisphere of the
brain are interconnected. This correlation between hand and language in both deaf
and hearing speakers, bolstered by the fact that symbolic gestures and speech are
processed in the same (left hemisphere) area of the brain (Xu et al, 2009) therefore
lends credence to the gesture-‐first argument.
4.2 Child Language

Another of Bickerton’s ‘living fossils’ (1990:105), child language, may represent what
a protolanguage may have been like in our forebears. Following Haeckel’s (1866)
‘ontogeny repeats phylogeny’ theory, in a more modern sense applied to language
evolution by Bickerton (1990:15) where ‘the ontogenetic development of language
partially replicates its phylogenetic development’, when applied to both gesture and
speech, an analysis of the capabilities of deaf and hearing children can elucidate what
part gesture played in language emergence.

26

4.2.1
Manual
Babbling

Laura Petitto (2000:4) describes that both deaf and hearing children begin to acquire
their respective signed and spoken languages at the same rate and at the same ages
of development, starting with babbling at around 7 months, right through until the 2-‐
word stage at around 16-‐22 months. Deaf children exposed to sign language alone by
their sign language-‐using parents typically exhibit a manual babbling stage involving
the performance of discrete elements of sign language in much the same way as
hearing children manipulate the spoken sound units of their language, e.g. ga-‐ga-‐ga
(Petitto, & Marentette, 1991). This implies that gesture is a modality in which
language is pre-‐programmed to thrive, and is just as natural and useful as a vocal
system. While babbling was previously understood to have been a precursor to
speech, it is now more accurate to describe it as a precursor to language, as it can be
achieved in either modality (Corballis, 2002).
4.2.2
Children’s
Gestures

Manual gestures are also observed in hearing children, and frequently occur before
they learn to speak: they point to objects to draw an adult’s attention before they
assign the object a word, and the earlier this happens the earlier the child will
produce a word for the object, suggesting an association between gestures and the
development of language (Özçaliskan & Dimitrova, 2013). These deictic gestures (i.e.
pointing) aid infants in understanding the association between symbols and referents,
as well as establishing the beginnings of joint attention at around one year of age-‐
children do not just point to objects for requests, they also point to objects already
within an adult’s gaze, indicating that attention to the object is shared (Tomasello,
2008). As mentioned previously, joint attention is pivotal for language development,
and the observation in children that joint attention is observed in manual gestures
before speech manifests itself strengthens the gestural argument.
Children also display the use of iconic gestures, which emerge slightly later
than deictic gestures, around 11-‐12 months (Özcaliskan & Goldin-‐Meadow, 2005).
Although less frequent than other gestures, these are far more language-‐like, assign
properties to referents and allow greater freedom than words in describing and
assigning properties to objects in the real world, much as our mute ancestors would

27

have had cause to do. Essentially, most argue that infants, provided with some kind of
input, use gestures more frequently to refer to objects and activities before they use
words for the same cause (Bates, 1976; Özcaliskan & Goldin-‐Meadow, 2005). Gesture
use also paves the way for children’s first nouns (Iverson & Goldin-‐Meadow, 2005)
and predicts the richness of their future language: those who use more iconic
gestures earlier in life develop larger vocabularies by 2 years of age, showing a strong
link between gesture use and overall language ability (Acredolo & Goodwyn, 1988;
Özçaliskan & Dimitrova, 2013).
Iverson et al (1994) observed hearing Italian children between 16 and 20
months of age to assess their gesture use; an interesting finding was that while the
children initially relied on agents to bolster their labelling, e.g. drinking from a toy cup
instead of copying the motion of drinking with the hand alone, this activity had
significantly diminished by 20 months. Instead, the children increasingly used
gestures dependent on movement without the use of an agent, e.g. flapping arms for
bird, and predicate gestures, e.g. holding the fingers close together to signify small.
They argue that this supports a theory in which gestures, over the course of cognitive
development become decreasingly context-‐bound, with the use of vehicles less
necessary as the child develops the ability to represent objects symbolically. This
supports Werner and Kaplan (1963) who argue that gestures help establish a
framework for a transition from object-‐bound communication to less object-‐related
gestures through to abstract symbolic representations that are then used in word-‐
referent relationships. This brings to mind the process of conventionalisation, ‘the
shift over tome from iconic gestures to arbitrary symbols’ (Gentilucci and Corballis,
2006:950) which is further explored in the following section in relation to novel sign
languages.
4.3 Novel Sign Languages
While dominant sign languages such as ASL and BSL have become ubiquitous,
established languages in modern culture, new sign languages, established over a
short period of time in differing contexts have been taken as support for a gesture-‐
first account (Fay et al, 2014, Sandler et al, 2005). The emergence of pidgin and creole
sign languages, such as Nicaraguan Sign Language (LSN) and Al-‐Sayyid Bedouin Sign

28

Language (ABSL), as well as the well-‐documented, widespread phenomenon of
‘homesign’ (Goldin-‐Meadow, 2003) has shed light on the properties and evolution of
an embryonic language. Greenfield et al (2008:36) describe these ‘languages’ as ‘the
linguistic limit of what can be developed without a cultural environment provided by
language-‐using humans.’ In this sense, they are the nearest equivalent to a system
that may have been utilised by pre-‐linguistic hominids; a protolanguage produced in
the absence of an established language-‐enriched environment.
4.3.1
Homesign
in
Deaf
Children

Deaf children who grow up in homes with hearing parents who do not use sign
language to communicate have demonstrated their own communicative system that
has been coined ‘homesign’ (Goldin-‐Meadow & Mylander, 1984). Children develop
these systems spontaneously in an environment devoid of an appropriate language
community; in this sense they have no usable linguistic input, and are ‘truly creating
language from scratch’ (Fay et al, 2014:9). Goldin-‐Meadow argues that ‘[t]he
children…lack access to a useable model of language…the gestures that the deaf
children use to communicate are structured in language like-‐ways. The children are
inventing their own, simple language’ (2003:xvii). The claim that homesign constitutes
a language per se is controversial (Morgan, 2005), but it does seem likely that this
idiosyncratic, simple, proto-‐grammatical system may recapitulate the features of a
gestural protolanguage that may have been present in our ancestors. Goldin-‐Meadow
(2002:369) herself acknowledges this potential ‘these are forces that are likely to play
a role in language creation every time it takes place, perhaps even the first time’.
Below is an example of the typical structure of homesign, taken from Slobin
(2004:13):
Patient + act (e.g., CHEESE EAT)
Actor + act (e.g., YOU MOVE)
Patient + act + agent (e.g., SNACK EAT YOU)
This displays a two or three-‐word ordering of signs, and a kind of proto-‐grammar of
the type that has previously been discussed in language-‐trained apes, as well as the
early language of hearing children. In addition, homesign displays noun-‐verb
distinction, considered a language universal (Smith, 1999). For example, one of the

29

participants observed by Goldin-‐Meadow et al (1994) differentiated between nouns
and verbs in different contexts. When using the sign for ‘twist’ in the verb sense, e.g.
‘twist the jar open’, he was more likely to produce the sign with (i) without
abbreviation, i.e. performing the twisting gesture multiple times, (ii) with inflection, in
this case gesturing towards an object to be twisted, and (iii), the gesture is performed
after indicating the object to be twisted. In contrast the gestural noun version of this,
e.g. ‘a twistable object’ is produced only once, in a neutral position, normally near to
the body, and before indicating the object (Goldin-‐Meadow, 2006).
Goldin-‐Meadow (2003) suggests that although homesign does exhibit some
morphological, lexical and syntactic complexity, the signs tended to be mainly
referential when the signer is limited to a group, essentially, of one (themselves).
However, she also maintains that the most robust, essential features of language
remain, those that are necessary for a communicative system to work. Homesign, left
to this group of one, stagnates and does not progress to full language (Slobin, 2005).
However, when this group of homesigners is expanded away from parents
who do not enrich the child’s experience and are put in contact with like-‐minded
interlocutors, the possibility of novel sign languages to become fully-‐fledged is
exponentially increased. The crucial factor is an interacting community, providing an
‘alignment between speakers [which] is essential for a lexicon to stabilize’ (Fay et al,
2014:10). This is the focus of the following section.
4.3.2
Nicaraguan
Sign
Language,
(LSN)
and
Idioma
de
Signos
Nicaragünese
(ISN)

The activity of homesign takes on an increased significance when those who use it are
suddenly removed from a speech-‐dominated sphere and subsequently immersed in a
deaf, sign-‐dominant culture. This is precisely what happened when Nicaragua opened
its first school for the deaf in 1978; the children, who previously had no interaction
with other deaf people or sign language, had each already devised their own system
of homesign (Senghas, 1995). When they came together at the new school they were
taught lip reading and Spanish but with limited success. However, when they were
allowed to interact with each other using their various homesign systems, which were
essentially pidgins, they began to converge on a simple sign language, LSN (Senghas &
Coppola, 2001). This was also essentially a pidgin, with a simple structure and little to

30

no grammar, and was used by the first entrants to the school in 1978. Since then, the
younger children who enter the school have been exposed to LSN by the older
children, and have consequently produced a more complex, compact, primary sign
language with grammar, ISN. Greenfield, Lyn and Savage-‐Rumbaugh assert that ‘the
sign language codified and became more complex with each succeeding generation’
(2010:36) in this sense the pidgin become a creole over time. The system, created
through ‘abrupt creolization’ (Senghas, 1995:1) contains inflectional verb
morphology, noun classifiers and other features unique to fully-‐fledged languages.
Senghas & Coppola (2001:328) argue that ‘[t]he emergence of Nicaraguan Sign
Language offers an opportunity to examine the processes common to language
learning, language change, and language genesis’. The ability of these children to
essentially create a language where none existed before, especially the evolution
from creating a homesign system in the absence of linguistic input to the creolization
of a new, fully fledged language, demonstrates the capacity of language to develop
from basic, iconic gestures to a fully grammatical system in the manual mode. This
window into early language emergence is viable not only in Nicaraguan sign language
and homesign, but also for a more recently studied novel sign language, Al-‐Sayyid
Bedouin Sign Language.
4.3.3
Al-‐Sayyid
Bedouin
Sign
Language
(ABSL)

This is another sign language that has appeared de novo, in a smaller population than
LSN, in a Bedouin community in the Negev desert in Israel. The inhabitants have an
unusual tendency for deafness, with around 150 out of 3,500 members having
inherited a condition leaving them profoundly deaf. The sign language that has been
created is now in its third generation, having been developed over approximately the
last 70 years (Senghas, 2005).
In this time researchers have found that the language is completely distinct
from both spoken and other sign languages found nearby such as Israeli Sign
Language, which has both a different word order and is acknowledged as different by
signers of both languages (Sandler et al, 2005). ABSL is now recognised as a fully-‐
fledged sign language, able to express a variety of abstract ideas and events displaced
from the present (Fox, 2008). In addition, (Sandler et al, 2005:2661) note that ‘In the

31

space of one generation from its inception, systematic grammatical structure has
emerged in the language’. This grammar emerged in the absence of outside influence
from other languages, and was formed after a conventionalised set of lexical items
had already been established, showing a gradual increase in linguistic complexity akin
to the way language might have originally emerged.
Sandler et al (2005) also found that the word order employed in ABSL was
overwhelmingly SOV. This is interesting when paired with research from Goldin-‐
Meadow et al (2008), which found that hearing speakers of various languages all
abandon their language’s own word order when asked to describe events using
gesture without speech in favour of the same SOV word order in different non-‐verbal
tasks. This suggests that there may be an innate, natural human tendency for this
particular word order used in gestural communication, and it ‘may reflect a natural
disposition that humans exploit not only when asked to represent events nonverbally,
but also when creating language anew’ (2008:9167). This concurs with Newmeyer’s
(2000) postulation that early protolanguage is likely to have had an SOV word order.
Sandler et al (2005:2665) add: ‘The appearance of this conventionalization at such an
early stage in the emergence of a language is rare empirical verification of the unique
proclivity of the human mind for structuring a communication system along
grammatical lines.’
4.3.4
Creating
a
New
Communication
System
from
Scratch

Natural languages created from scratch have been discussed in 4.3.2 and 4.3.3. and
the below describes how a new language was created and developed in a simulated
community over a short period of time.
An additional finding of Pollick and de Waal’s ape gesture study (2007),
discussed in 2.2, was that bonobos used gestures more frequently than chimpanzees
to initiate a social interaction, 78% of the time, and that both species used gestures
alone more frequently than vocalisations or a combination of the two (Fig. 6).

32

The success of gesture to both initiate interactions as well as to solicit
responses in the two groups echoes Fay et al’s (2014) study in which a group of
people were tasked with creating a communication system from scratch. They found
that gestures were the most effective means of conveying meaning from one person
to another where no shared language was available to them (Fig. 7). Even when
gesture was combined with speech, this was found to be distracting and was less
effective than the use of gesture alone.

The study reveals a crucial point that I believe may have been pivotal in the
evolution of our own language: ‘participants initially use iconic signs to ground shared
0

20

40

60

80

100

Gestures
Facial/
Vocal
Combination

Percentage
of
the
time

(%)

Initiation
of
Social
Interaction

Chimpanzees

Bonobos

Figure
6.
Frequency
of
interaction
type.
Data
from
Pollick
&
de
Waal
(2007)

Figure
6:
Success
of
each
type
of
signal,
judged
by
accuracy
of

identification.
Taken
from
Fay
et
al
(2014:5).

33

meanings, and over subsequent interactions these signs become increasingly aligned,
symbolic and language like’ (Fay et al, 2014:3). This echoes the findings of Iverson et
al (1994) about conventionalisation from the previous section, as well as with
Corballis’ theory that gestural signals could have ‘eventually conventionalized so that
other forms of representation, including spoken and written words, as well as more
abstract manual gestures, could suffice to carry the message’. (Corballis 2009:109).
Conventionalisation may have been a pivotal process in the emergence of
human language: manual gestures are the most likely candidate to have been the
original form of communication between cognitively evolved proto-‐hominids, as they
have ‘at least the potential to represent concepts iconically rather than in abstract
form. Once a set of iconic representations is established, increasing usage can then
lead to more stylized and ultimately abstract representation’ (Corballis, 2000). This
process is not a recent development among the deaf, and has been observed
naturally for at least hundreds of years. Darwin (1965/1872:64) quotes W.R. Scott’s
The Deaf and the Dumb (1870:12):

This contracting of natural gestures into much shorter gestures than
the natural expression requires is very common amongst the deaf and
dumb. This contracted gesture is frequently so shortened as nearly to
lose all semblance of the natural one, but to the deaf and dumb who
use it, it still has the force of the original expression.
De Waal (1982) has previously noted that primate gestures also become
conventionalised over time, from actions centred around objects to symbolic gestures
on their own, much like the process that is observed in homesigning children and
novel sign languages.
The importance placed by Saussure on the ‘arbitrariness of the sign’ (1916) as
a prerequisite for language has been a stumbling block in the attempt to classify sign
languages as full languages, since a large amount of signs are iconic in nature
(Corballis, 2012b). However, the examination of these novel sign languages and the
process of conventionalisation show that iconicity is not a necessity for signed
languages: original signs may be iconic, but over time these acquire aspects of
arbitrariness such as in the creolization from the more iconic LSN to the more
symbolic and language-‐like ISN. Furthermore, arbitrariness is often achieved as the

34

result of a need for expedience and convenience: Corballis (2009:32) quotes Charles
Hockett (1978:274-‐275):

When a representation of some four-‐dimensional hunk of life has to be
compressed into the single dimension of speech, most iconicity is
necessarily squeezed out. In one-‐dimensional projections, an elephant is
indistinguishable from a woodshed. Speech perforce is largely
arbitrary…we have learned to make a virtue of necessity.

The need for concision, speed and efficiency may well have been a driving force in the
transition from a primarily gestural to a primarily vocal mode in Homo sapiens, to
coincide with the increase in complexity of human culture through time (Corballis,
2009).
5.
But
why
the
switch
to
speech?

Michael Corballis (2009:24) acknowledges the difficulty in explaining how if an original
system of gestures existed, then why is language today primarily spoken. He quotes
Robbins Burling (2005:123):

[T]he gestural theory has one nearly fatal flaw. Its sticking point has
always been the switch that would have been needed to move from a
visual language to an audible one.

Corballis then argues that the shift was a gradual process, and that the motor theory
of speech perception and the concept of ‘speech as gesture’ can go some way to
explaining the shift from a gestural modality to a spoken one. He cites evidence from
articulatory phonology, which posits that speech is itself a system of gestures of the
mouth, lips and so on, which is bolstered by the discovery of the McGurk effect
(McGurk & MacDonald, 1976). This is the phenomenon that when a sound is played
over the top of a video of a person producing a different speech sound, the viewer
reports hearing a different sound entirely to the one being spoken. However for me
this particular aspect of his argument is unsatisfactory, as the evidence against this
theory is somewhat insurmountable: the McGurk effect has been found to occur in

35

non-‐linguistic circumstances (Massaro 1998), and the theory is now generally seen as
false by the majority of linguists (Galantucci et al, 2006).
Nevertheless, others have attempted to explain how the transition may have
taken place with greater success: Arbib’s notion of an ‘expanding spiral’ (2005b:22) is
somewhat convincing:

Homo habilis through to early Homo sapiens had a protolanguage based
extensively on manual gestures (‘protosign’) which … provided essential
scaffolding for the emergence of a protolanguage based primarily on vocal
gestures (‘protospeech’)

While this is in line with my own argument, Stokoe (2002) elaborates upon this idea
to form a picture of language emergence: gestures were the original signs, iconically
representing animals, objects, and things in the real world. Arbitrary vocalisations at
this point in history would have been useless. Movements of the body may have
represented the actions of these referents, creating a rudimentary syntax of the type
seen in homesign. This is referred to as ‘semantic phonology’ (Stokoe, 2002:82), and
describes hand shapes being parsed into a primitive noun and verb phrase, i.e. the
hand and its movement. In this model, over time the basic structure for language
ability was therefore present in hominids, having built upon the abilities of the LCA,
and bolstered by the advent of bipedalism. From this base of knowledge, the mirror
system propagated interaction between conspecifics, until eventually vocal signs
were incorporated into the repertoire, firstly scaffolding and then replacing manual
gestures as the anatomy of the vocal tract and brain became more suited to volitional
speech, at around the emergence of Homo sapiens.
Some also argue that natural selection has its place in a switch from the
manual to vocal mode (Pinker & Bloom, 1990): speech is less energy consuming than
manual gesturing, provides a method of communicating in the dark, and frees the
hands for manufacturing and pedagogy (Corballis, 2002). The switch to speech,
therefore, may have been advantageous in our ancestors, leading to the demise of
the Neanderthals as their language abilities languished, and the ‘human revolution’ of
Homo sapiens that began their domination of the planet. Kim Sterelny (2012:2143)

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