Emerging Trends in The Social and Behavioral Sciences

Gestural Communication in Nonhuman Species

Item

Title

Gestural Communication in Nonhuman Species

Author

Pika, Simone

Research Area

Social Interactions

Topic

Primate Studies

Abstract

The evolution of language remains one of science's greatest mysteries. Although first comparative investigations into language origins focused on vocal abilities of nonhuman animals, especially primates, the number of publications reporting new and fascinating results about gestural skills of nonhuman animals has notably increased. To get a better insight in this intriguing scientific field, the present essay will provide a brief overview of its history and will then pinpoint current trends and future avenues.

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Identifier

etrds0147

extracted text

Gestural Communication in
Nonhuman Species
SIMONE PIKA

Abstract
The evolution of language remains one of science’s greatest mysteries. Although first
comparative investigations into language origins focused on vocal abilities of nonhuman animals, especially primates, the number of publications reporting new and
fascinating results about gestural skills of nonhuman animals has notably increased.
To get a better insight in this intriguing scientific field, the present essay will provide a brief overview of its history and will then pinpoint current trends and future
avenues.

INTRODUCTION
Human language forms such an exception among the behaviors of animals that it has often been used to define what it means to “be human.”
Although there is still an ongoing debate concerning the definition of language, many theorists would agree that it embodies several communicative
modalities—the auditory, tactile, and visual one—and is used referentially to
direct and influence the attentional and mental states of others. The earliest
manifestations of the potent urge to engage in communicative activities can
already be observed in human children around the age of 9–12 months,
when they start to use gestures, sounds, and/or a combination of both to
obtain objects, and affect the thinking and behavior of other individuals.
This behavior is so different from the vocal and gestural languages of other
animals that it calls for an evolutionary investigation (Botha & Knight, 2009).
Why do only humans have language?
Theories of the origins of language must account for the extremely short
phylogenetic time available for the evolution of this highly sophisticated
behavior. Some suggest that our hominin ancestors did not possess the
anatomical and neural prerequisites to produce spoken language, at least
until very recently (Lieberman, 2002; although this view is challenged
by Fitch (2009). A recent study by Krause et al. (2007) shows that our
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

1

2

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

closest extinct relatives, the Neanderthals, share with modern humans two
evolutionary changes in FOXP2, a gene that has been implicated in the development of speech and language (Lai, Fischer, Hurst, Vargha-Khadem, &
Monaco, 2001). Diller and Cann (2009) suggest a gradual coevolution of
language and the complex brain structures necessary for speech and fully
modern language, with the mutations in FOXP2 occurring some 1.8 million
years ago, when human brains doubled in size from the 450 cc brains of
chimpanzee (Pan troglodytes) and australopithecines to the 1350 cc brains of
modern humans. This time period is relatively short and clearly insufficient
for the evolution of the entire cognitive apparatus required for normally
developed linguistic behavior, suggesting that many of the neural, anatomical, and cognitive components required for language processing must be
substantially older, having evolved in the primate lineage long before the
advent of speech in modern humans.
THE COMPARATIVE APPROACH
A powerful approach to problems of language evolution is provided by the
comparative method, which uses empirical data from living species to draw
detailed inferences about the behavior of extinct ancestors. Although scholars interested in the evolution of language have often ignored comparative
data altogether or focused narrowly on only data from nonhuman primates
(hereafter primates), recent developments in neuroscience, molecular biology, and developmental biology indicate that many aspects of neural and
developmental function are highly conserved, encouraging the extension
of the comparative method to all vertebrates (and perhaps beyond, Hauser,
Chomsky, & Fitch, 2002). Furthermore, recent archaeological evidence
suggests, that early hominins and extant apes are remarkably divergent in
many anatomical features (e.g., dentition and feet; Lovejoy, 2009). Thus, in
order to reconstruct the changes that paved the way for language to evolve,
we should consider the likely adaptations of early hominins generally, rather
than only with specific reference to living chimpanzees (Lovejoy, 2009).
Detailed insight into the communicative abilities of our closest phylogenetic
relatives, the nonhuman primates, can thus by both homology and analogy,
help in reconstructing the behavior of the last common ancestor of Pan
and Homo and perhaps some aspect of early hominin behavior. Examples
of convergent evolution in distant related species can provide clues to the
types of problems that particular morphological or behavioral mechanisms
are “designed” to solve (Gould, 1976).
Furthermore, in order to claim that particular components of human language are unique to humans, data indicating that no other animal has this
particular trait is required.

Gestural Communication in Nonhuman Species

3

As we tend to associate language first with sound rather than movement,
the majority of comparative research in relation to language origins focused
on vocalizations (Marler, 1970; Seyfarth, 2005). However, speech consists
of over 100 acoustically unique phones, commonly combined into rapid
sequences, which serve as the main carriers of meaning. Thus the ability
to produce speech relies heavily on fine, rapid and voluntarily produced
motor movements synchronized with cognitive activity. In addition, McNeill
recently stated “that language could not have come into existence without
gesture” (McNeill, 2012, p. 59). To understand the evolutionary precursors of
human language and the linkage between speech and gesture, we therefore
also need to gain a profound knowledge of gestural forms, their usage and
their function in nonhuman animals. The present essay aims to provide a
brief overview of the history of this scientific field and will then focus on
current trends and future avenues in this exciting research domain.
BRIEF HISTORY OF COMPARATIVE GESTURAL RESEARCH
Earliest comparative studies on gestural skills were mainly descriptive
and focused on our closest living relatives, the great apes. Ladygina-Kohts
(1935) for instance compared the expressive behavior of a chimpanzee and
a human child and concluded that the initial language of both species,
consisting of gestures, facial expressions and vocalizations, is quite similar. Since attempts to teach human speech to chimpanzees had failed,
researchers tried to overcome great apes’ difficulties in speech production
by switching to the manual modality. The first language projects centered
on three chimpanzee females, Sara, Lana, and Washoe, and used different
methodologies to communicate: (i) three-dimensional plastic pieces; (ii)
two-dimensional geometric designs; and (iii) manual signs (Gardner &
Gardner, 1969; Premack & Premack, 1972; Rumbaugh, Gill, & von Glaserfeld, 1973). One of the most successful studies was the sign language
project carried out by the Gardners (1969), who raised a chimpanzee female,
Washoe, in a house trailer exposing her to human caretakers communicating
via American Sign Language (ASL) only. Washoe learned to use over a
hundred of signs in appropriate ways, invented new signs and was also
able to modulate taught signs in new purposeful ways. In addition, she
formed sequences of signs, which mainly followed two principles: (i) more
urgency ⇒ more signs and (ii) Addressee–Action–Nonaddressee (McNeill,
2012). The Addressee (or “donor”)–Action–Nonaddressee (or “recipient”
and always Washoe) sequence represents an iconic model by depicting
the desired result. However, contrary to human language, which is most
notably used to communicate and interact in bubbles and hallucinations of
thought, about today but also yesterday and tomorrow, Washoe’s sequences

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

mainly concerned objects and events in the here and now and communicated specific demands to meet specific wants with herself as beneficiary
(McNeill, 2012). Although this and other ape language projects seemed
to suggest that apes are able to converse with human caretakers via true
symbols, there were several criticisms: First, the apes may have only learned
basic conditioned associations between various food items and symbols
instead of true symbolic communication (Savage-Rumbaugh, 1979). Second,
the methods applied in sign-language studies and all other ape language
projects (e.g. Premack & Premack, 1972; Rumbaugh et al., 1973) differed
significantly from language acquisition in normally developing human children. Human children acquire linguistic symbols through joint attentional
frames that involve the intertwining of both linguistic and gestural means
and actions between two or more individuals, starting very early with
simple rule-oriented turn-taking games such as peek-a-boo. Furthermore, in
these social situations, children do not simply learn words concerning food
or object names only or sentence structure, but also “how to be” and “how
to interact” in a wide range of settings. Even more crucially, they start to
understand caretakers’ specific communicative intentions as expressed in
an utterance.
Contrary to this learning environment, language-trained apes were typically taught to produce a symbol when a food item or object was held up
in front of them or when a desired activity was withheld, assuming that
comprehension would follow production naturally. For instance, if Washoe
wanted a drink from the experimenter, she was required to sign “drink” in
order to obtain it; if she wanted to go outdoors she was required to sign
“open” before she would be allowed to leave, and so on. Contrary, just using
a pointing gesture to the drink or the door was not considered an acceptable means of communicating the same intent. Similarly, if Sarah wanted an
apple that was in front of her, she was only allowed to use a very limited communicative mean: placing the proper plastic chip on the tray to “name” the
apple. If Lana wanted M&Ms in the dispenser, she had to press the buttons
on the keyboard “Please machine give M&M.” Terrace (1979) thus argued
that the apes in these scenarios sign only as a “way out,” suggesting that
their symbol production and comprehension are not reflective of comparable levels of cognitive comprehension in normally developing children.
Furthermore, McNeill (2012) proposed that not only differences in nonhuman primates’ mouth-anatomy but the lack of a thought-language-hand link
brain to orchestrate mouth-part movements are the reason why nonhuman
primates have not developed language.
In response to these criticisms, Savage-Rumbaugh and colleagues aimed
to develop succinct, systematic procedures to push apes past the initial
stage of using associations instrumentally and to enable true symbolic

Gestural Communication in Nonhuman Species

5

comprehension and usage (Savage-Rumbaugh, 1979). They used again
the electronically activated, computer-interfaced keyboard invented for
the Lana project. The keys represent noniconic graphic symbols of one
of more elements of nine basic geometric patterns, analogous to letters
of the alphabet. The first teaching sessions circled around continuous
one-to-one contact of four chimpanzees with a human teacher, encouraging the communicative and cognitive abilities of the apes by presenting
and naming single nonfood items. After 4 months however, not a single
chimpanzee showed any sign of learning names for the training objects.
Instead of focusing on the task itself, the apes directed their main efforts and
attention toward the experimenter to influence his decision to hand out a
reward AFTER the trial. Savage-Rumbaugh (1979) therefore adjusted their
experimental procedure by removing the decision-making process from the
experimenter and by giving him the role of a helper rather than a judge
of individual’s performance. Although two of the chimpanzees, Sherman
and Austin, learned to use the keyboard’s symbols to request food, trips
out of doors, blankets, and behaviors such as grooming and tickling, the
biggest success of this scientific adventure originated by unintentionally
matching the language learning process in normally developing human
children (Savage-Rumbaugh, Rumbaugh, & McDonald, 1985). At that time,
Savage-Rumbaugh et al. (1985) had also started working with a wild-caught
adult bonobo (Pan paniscus) female, Matata, exposing her to the same
established experimental procedure and showing her to use the keyboard
to request foods, objects and certain behaviors. Matata, however, while not
very successful in symbol acquisition herself, had a 6 months old stepson
Kanzi, who did not receive any particular training but was always with
Matata during the training sessions. At the age of 12 months, he started
to show a playful interest in the keyboard and at the age of 2.5 years he
switched to selecting specific symbols. Even more surprising, however, he
combined specific keys with gestures, for instance he would produce the
lexigram for “ball” and then gesture toward his ball to request that the ball
was brought to him. Alternatively, he pressed the lexigram for “tomatoes,”
which represented a distinct location in the enclosure and gestured in the
direction of it.
Furthermore, Kanzi started to request food via lexigrams and was also able
to name foods he had observed Matata learning. His behavior thus showed
that he had acquired lexigrams spontaneously by observing his mother. In
addition, he had learned many of the lexigrams his mother had not and was
able to understand the symbols bidirectionally, which means that he was able
to produce and to comprehend them without any specific training. The subsequent procedure used with Kanzi was therefore to keep the exposure of
lexigrams as natural as possible. His human caretakers used symbols when

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

communicating, encouraged him to do so as well and thus functioned as
communicative models. In addition, as the enclosure consisted of 55 acres
of forest, Kanzi’s food was dispersed daily throughout the forest, enabling
him to search for and discover it in a more natural way. In many ways his
early vocabulary matched the early vocabularies of human children, including names for individuals, labels for common objects, words for actions, locations and properties. It included even a few function words such as “no”
and “yes.” However, similar to the apes in the sign-language projects, Kanzi
mainly communicated about objects and events (i) in the here and now and
(ii) benefiting merely his own goals and desires.
In parallel, researchers also had started to investigate the behavior of
primates in their natural environments, including detailed descriptions
of communicative signals such as vocalizations, facial expressions, and
gestures. However, the first step toward an understanding of the cognitive
complexity underlying the natural communication abilities of great apes
was done by Plooij (1978) studying the ontogeny of gestural signals in
chimpanzees at Gombe, Tanzania. He applied methods of Speech Acts
Theory and parameters used in analyses of intentional behavior in human
prelinguistic human children. Plooij showed that gestures of chimpanzees
resemble those of prelinguistic human children in some important ways:
They are (i) characterized by their flexible relation between means and
ends (means-ends dissociation) and (ii) used to attract and redirect attention. Means-ends dissociation suggests that individuals are able to use (i)
synonymous signals/gestures to achieve a certain outcome/goal and (ii)
ambiguous gestures for different outcomes/goals (Pika & Liebal, 2012b).
Examples for synonymous gestures are the gestures TOUCH and REACH OUT
ARM, which are both used by chimpanzee infants to communicate to the
mother to be picked up and thus carry the same message. The gesture ARM
RAISE however is an example for an ambiguous gesture because it is used
to solicit grooming but also to calm and appease an anxious conspecific,
thereby communicating and embodying different messages across contexts.
This cognitive approach to gestural signaling was continued and expanded
by Tomasello and his research group, who provided the first systematic
evidence that gestural skills of apes are far more complex and sophisticated
than their vocal abilities (Call & Tomasello, 2007). By creating the first
comprehensive database on gestural signaling of the four great ape species
and one smaller ape (siamangs), they showed that apes
•

use open-ended, multifaceted gestural repertoires, including speciesdistinctive and species-indistinctive gestures, whose meaning and usage
has to be learned;

Gestural Communication in Nonhuman Species

•

•

7

use gestures as flexibly produced intentional strategies such as (i)
recipient specificity, (ii) persistence to the goal (e.g., repetition of a
gestures or use of a different one until the goal has been achieved), (iii)
means-ends dissociation (see paragraph above), and (iv) adjustment to
audience effects such as (1) adaption of signal category to the attentional
states of recipient and (2) locomoting in the visual field of the recipient
before producing a visual gesture; and
develop group-specific traditions of gesture, implying that underlying
social learning processes are involved.

Tomasello recently emphasized the impact of these findings on scenarios of
language evolution by noting: “In all, I personally do not see how anyone can
doubt that ape gestures—in all of their flexibility and sensitivity to the attention of the other—and not ape vocalizations—in all of their inflexibility and
ignoring of others—are the original font from which the richness and complexities of human communication and language have flowed” (Tomasello,
2008, p. 55).
CURRENT DEVELOPMENTS AND FUTURE AVENUES
In recent years, the number of publications reporting new and fascinating
results about the gestural skills of primates has increased impressively (for
an overview see Pika & Liebal, 2012a). Although scientific investigations still
disproportionally concentrate on gestural skills of (i) common chimpanzees
(P. troglodytes); (ii) primates living in captive environments; and (iii) signalers
of gestural interactions rather than recipients or both, a considerable amount
of research interest has now shifted toward the gestural abilities of species
in natural environments (e.g., Genty, Breuer, Hobaiter, & Byrne, 2009; Pika &
Mitani, 2006; Roberts, Vick, & Buchanan-Smith, 2012), as well as monkeys
(e.g., Maestripieri, 2005; Meguerditchian & Vauclair, 2006).
In addition, current trends and debates concern
•
•
•
•

the origins of gestures;
gestural usage;
the neural substrates of gestural signaling; and
the application of new methods.

The most intriguing research avenue toward an in-depth understanding of
the evolutionary pressures acting upon gestural systems, however, concerns
systematic investigations into the cognitive complexity underlying the visual
and tactile signals of nonprimate taxa (Pika & Bugnyar, 2011). Although in the
past century, ethologists and ornithologists had been especially fascinated

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EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

with courtship and threat displays of birds (Huxley, 1923; Lorenz, 1939), and
fish (Dominey, 1983), these signals were mainly interpreted as fixed action
patterns rather than complex cognitive means.
Recently, however, Kaplan (2011) reported that Australian magpies (Gymnorhina tibicen), which are highly social and cooperative songbirds, use a distinct posture to “point out” the position of a predator to their conspecifics.
In addition, Pika and Bugnyar (2011) investigated the gestural behavior of
another cooperative songbird species, ravens (Corvus corax) in their natural
communicative interactions in the wild. They showed that ravens use gestures to refer to outside entities and to share attention with conspecifics. Since
referential gestural signals had so far been only described in humans and
great apes (for an overview see Pika, 2012), it seems that our understanding of gestural systems is only at its beginning and that future research will
provide a viable base from which we may draw informed inferences about
gestures and its importance for language origins.
ACKNOWLEDGMENTS
I am grateful to Wolfgang Wickler for fruitful discussions and Sue Anne
Zollinger for constructive help with editing the essay. This project was
supported by a Sofja Kovalevskaja Award of the Alexander von Humboldt
Foundation.
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SIMONE PIKA SHORT BIOGRAPHY
Simone Pika is the head of the Humboldt Research Group on “Comparative Gestural Signalling” at the Max Planck Institute for Ornithology in
Seewiesen, Germany. Her PhD at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, focused on gestural complexity and
underlying cognitive skills of great apes. She held research fellowships at the
University of Alberta, Canada, and the University of St. Andrews, Scotland,
and a post as Assistant Professor at the University of Manchester, UK.

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Gestural Communication in Nonhuman Species

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Gestural Communication in
Nonhuman Species
SIMONE PIKA

Abstract
The evolution of language remains one of science’s greatest mysteries. Although first
comparative investigations into language origins focused on vocal abilities of nonhuman animals, especially primates, the number of publications reporting new and
fascinating results about gestural skills of nonhuman animals has notably increased.
To get a better insight in this intriguing scientific field, the present essay will provide a brief overview of its history and will then pinpoint current trends and future
avenues.

INTRODUCTION
Human language forms such an exception among the behaviors of animals that it has often been used to define what it means to “be human.”
Although there is still an ongoing debate concerning the definition of language, many theorists would agree that it embodies several communicative
modalities—the auditory, tactile, and visual one—and is used referentially to
direct and influence the attentional and mental states of others. The earliest
manifestations of the potent urge to engage in communicative activities can
already be observed in human children around the age of 9–12 months,
when they start to use gestures, sounds, and/or a combination of both to
obtain objects, and affect the thinking and behavior of other individuals.
This behavior is so different from the vocal and gestural languages of other
animals that it calls for an evolutionary investigation (Botha & Knight, 2009).
Why do only humans have language?
Theories of the origins of language must account for the extremely short
phylogenetic time available for the evolution of this highly sophisticated
behavior. Some suggest that our hominin ancestors did not possess the
anatomical and neural prerequisites to produce spoken language, at least
until very recently (Lieberman, 2002; although this view is challenged
by Fitch (2009). A recent study by Krause et al. (2007) shows that our
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

1

2

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

closest extinct relatives, the Neanderthals, share with modern humans two
evolutionary changes in FOXP2, a gene that has been implicated in the development of speech and language (Lai, Fischer, Hurst, Vargha-Khadem, &
Monaco, 2001). Diller and Cann (2009) suggest a gradual coevolution of
language and the complex brain structures necessary for speech and fully
modern language, with the mutations in FOXP2 occurring some 1.8 million
years ago, when human brains doubled in size from the 450 cc brains of
chimpanzee (Pan troglodytes) and australopithecines to the 1350 cc brains of
modern humans. This time period is relatively short and clearly insufficient
for the evolution of the entire cognitive apparatus required for normally
developed linguistic behavior, suggesting that many of the neural, anatomical, and cognitive components required for language processing must be
substantially older, having evolved in the primate lineage long before the
advent of speech in modern humans.
THE COMPARATIVE APPROACH
A powerful approach to problems of language evolution is provided by the
comparative method, which uses empirical data from living species to draw
detailed inferences about the behavior of extinct ancestors. Although scholars interested in the evolution of language have often ignored comparative
data altogether or focused narrowly on only data from nonhuman primates
(hereafter primates), recent developments in neuroscience, molecular biology, and developmental biology indicate that many aspects of neural and
developmental function are highly conserved, encouraging the extension
of the comparative method to all vertebrates (and perhaps beyond, Hauser,
Chomsky, & Fitch, 2002). Furthermore, recent archaeological evidence
suggests, that early hominins and extant apes are remarkably divergent in
many anatomical features (e.g., dentition and feet; Lovejoy, 2009). Thus, in
order to reconstruct the changes that paved the way for language to evolve,
we should consider the likely adaptations of early hominins generally, rather
than only with specific reference to living chimpanzees (Lovejoy, 2009).
Detailed insight into the communicative abilities of our closest phylogenetic
relatives, the nonhuman primates, can thus by both homology and analogy,
help in reconstructing the behavior of the last common ancestor of Pan
and Homo and perhaps some aspect of early hominin behavior. Examples
of convergent evolution in distant related species can provide clues to the
types of problems that particular morphological or behavioral mechanisms
are “designed” to solve (Gould, 1976).
Furthermore, in order to claim that particular components of human language are unique to humans, data indicating that no other animal has this
particular trait is required.

Gestural Communication in Nonhuman Species

3

As we tend to associate language first with sound rather than movement,
the majority of comparative research in relation to language origins focused
on vocalizations (Marler, 1970; Seyfarth, 2005). However, speech consists
of over 100 acoustically unique phones, commonly combined into rapid
sequences, which serve as the main carriers of meaning. Thus the ability
to produce speech relies heavily on fine, rapid and voluntarily produced
motor movements synchronized with cognitive activity. In addition, McNeill
recently stated “that language could not have come into existence without
gesture” (McNeill, 2012, p. 59). To understand the evolutionary precursors of
human language and the linkage between speech and gesture, we therefore
also need to gain a profound knowledge of gestural forms, their usage and
their function in nonhuman animals. The present essay aims to provide a
brief overview of the history of this scientific field and will then focus on
current trends and future avenues in this exciting research domain.
BRIEF HISTORY OF COMPARATIVE GESTURAL RESEARCH
Earliest comparative studies on gestural skills were mainly descriptive
and focused on our closest living relatives, the great apes. Ladygina-Kohts
(1935) for instance compared the expressive behavior of a chimpanzee and
a human child and concluded that the initial language of both species,
consisting of gestures, facial expressions and vocalizations, is quite similar. Since attempts to teach human speech to chimpanzees had failed,
researchers tried to overcome great apes’ difficulties in speech production
by switching to the manual modality. The first language projects centered
on three chimpanzee females, Sara, Lana, and Washoe, and used different
methodologies to communicate: (i) three-dimensional plastic pieces; (ii)
two-dimensional geometric designs; and (iii) manual signs (Gardner &
Gardner, 1969; Premack & Premack, 1972; Rumbaugh, Gill, & von Glaserfeld, 1973). One of the most successful studies was the sign language
project carried out by the Gardners (1969), who raised a chimpanzee female,
Washoe, in a house trailer exposing her to human caretakers communicating
via American Sign Language (ASL) only. Washoe learned to use over a
hundred of signs in appropriate ways, invented new signs and was also
able to modulate taught signs in new purposeful ways. In addition, she
formed sequences of signs, which mainly followed two principles: (i) more
urgency ⇒ more signs and (ii) Addressee–Action–Nonaddressee (McNeill,
2012). The Addressee (or “donor”)–Action–Nonaddressee (or “recipient”
and always Washoe) sequence represents an iconic model by depicting
the desired result. However, contrary to human language, which is most
notably used to communicate and interact in bubbles and hallucinations of
thought, about today but also yesterday and tomorrow, Washoe’s sequences

4

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

mainly concerned objects and events in the here and now and communicated specific demands to meet specific wants with herself as beneficiary
(McNeill, 2012). Although this and other ape language projects seemed
to suggest that apes are able to converse with human caretakers via true
symbols, there were several criticisms: First, the apes may have only learned
basic conditioned associations between various food items and symbols
instead of true symbolic communication (Savage-Rumbaugh, 1979). Second,
the methods applied in sign-language studies and all other ape language
projects (e.g. Premack & Premack, 1972; Rumbaugh et al., 1973) differed
significantly from language acquisition in normally developing human children. Human children acquire linguistic symbols through joint attentional
frames that involve the intertwining of both linguistic and gestural means
and actions between two or more individuals, starting very early with
simple rule-oriented turn-taking games such as peek-a-boo. Furthermore, in
these social situations, children do not simply learn words concerning food
or object names only or sentence structure, but also “how to be” and “how
to interact” in a wide range of settings. Even more crucially, they start to
understand caretakers’ specific communicative intentions as expressed in
an utterance.
Contrary to this learning environment, language-trained apes were typically taught to produce a symbol when a food item or object was held up
in front of them or when a desired activity was withheld, assuming that
comprehension would follow production naturally. For instance, if Washoe
wanted a drink from the experimenter, she was required to sign “drink” in
order to obtain it; if she wanted to go outdoors she was required to sign
“open” before she would be allowed to leave, and so on. Contrary, just using
a pointing gesture to the drink or the door was not considered an acceptable means of communicating the same intent. Similarly, if Sarah wanted an
apple that was in front of her, she was only allowed to use a very limited communicative mean: placing the proper plastic chip on the tray to “name” the
apple. If Lana wanted M&Ms in the dispenser, she had to press the buttons
on the keyboard “Please machine give M&M.” Terrace (1979) thus argued
that the apes in these scenarios sign only as a “way out,” suggesting that
their symbol production and comprehension are not reflective of comparable levels of cognitive comprehension in normally developing children.
Furthermore, McNeill (2012) proposed that not only differences in nonhuman primates’ mouth-anatomy but the lack of a thought-language-hand link
brain to orchestrate mouth-part movements are the reason why nonhuman
primates have not developed language.
In response to these criticisms, Savage-Rumbaugh and colleagues aimed
to develop succinct, systematic procedures to push apes past the initial
stage of using associations instrumentally and to enable true symbolic

Gestural Communication in Nonhuman Species

5

comprehension and usage (Savage-Rumbaugh, 1979). They used again
the electronically activated, computer-interfaced keyboard invented for
the Lana project. The keys represent noniconic graphic symbols of one
of more elements of nine basic geometric patterns, analogous to letters
of the alphabet. The first teaching sessions circled around continuous
one-to-one contact of four chimpanzees with a human teacher, encouraging the communicative and cognitive abilities of the apes by presenting
and naming single nonfood items. After 4 months however, not a single
chimpanzee showed any sign of learning names for the training objects.
Instead of focusing on the task itself, the apes directed their main efforts and
attention toward the experimenter to influence his decision to hand out a
reward AFTER the trial. Savage-Rumbaugh (1979) therefore adjusted their
experimental procedure by removing the decision-making process from the
experimenter and by giving him the role of a helper rather than a judge
of individual’s performance. Although two of the chimpanzees, Sherman
and Austin, learned to use the keyboard’s symbols to request food, trips
out of doors, blankets, and behaviors such as grooming and tickling, the
biggest success of this scientific adventure originated by unintentionally
matching the language learning process in normally developing human
children (Savage-Rumbaugh, Rumbaugh, & McDonald, 1985). At that time,
Savage-Rumbaugh et al. (1985) had also started working with a wild-caught
adult bonobo (Pan paniscus) female, Matata, exposing her to the same
established experimental procedure and showing her to use the keyboard
to request foods, objects and certain behaviors. Matata, however, while not
very successful in symbol acquisition herself, had a 6 months old stepson
Kanzi, who did not receive any particular training but was always with
Matata during the training sessions. At the age of 12 months, he started
to show a playful interest in the keyboard and at the age of 2.5 years he
switched to selecting specific symbols. Even more surprising, however, he
combined specific keys with gestures, for instance he would produce the
lexigram for “ball” and then gesture toward his ball to request that the ball
was brought to him. Alternatively, he pressed the lexigram for “tomatoes,”
which represented a distinct location in the enclosure and gestured in the
direction of it.
Furthermore, Kanzi started to request food via lexigrams and was also able
to name foods he had observed Matata learning. His behavior thus showed
that he had acquired lexigrams spontaneously by observing his mother. In
addition, he had learned many of the lexigrams his mother had not and was
able to understand the symbols bidirectionally, which means that he was able
to produce and to comprehend them without any specific training. The subsequent procedure used with Kanzi was therefore to keep the exposure of
lexigrams as natural as possible. His human caretakers used symbols when

6

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

communicating, encouraged him to do so as well and thus functioned as
communicative models. In addition, as the enclosure consisted of 55 acres
of forest, Kanzi’s food was dispersed daily throughout the forest, enabling
him to search for and discover it in a more natural way. In many ways his
early vocabulary matched the early vocabularies of human children, including names for individuals, labels for common objects, words for actions, locations and properties. It included even a few function words such as “no”
and “yes.” However, similar to the apes in the sign-language projects, Kanzi
mainly communicated about objects and events (i) in the here and now and
(ii) benefiting merely his own goals and desires.
In parallel, researchers also had started to investigate the behavior of
primates in their natural environments, including detailed descriptions
of communicative signals such as vocalizations, facial expressions, and
gestures. However, the first step toward an understanding of the cognitive
complexity underlying the natural communication abilities of great apes
was done by Plooij (1978) studying the ontogeny of gestural signals in
chimpanzees at Gombe, Tanzania. He applied methods of Speech Acts
Theory and parameters used in analyses of intentional behavior in human
prelinguistic human children. Plooij showed that gestures of chimpanzees
resemble those of prelinguistic human children in some important ways:
They are (i) characterized by their flexible relation between means and
ends (means-ends dissociation) and (ii) used to attract and redirect attention. Means-ends dissociation suggests that individuals are able to use (i)
synonymous signals/gestures to achieve a certain outcome/goal and (ii)
ambiguous gestures for different outcomes/goals (Pika & Liebal, 2012b).
Examples for synonymous gestures are the gestures TOUCH and REACH OUT
ARM, which are both used by chimpanzee infants to communicate to the
mother to be picked up and thus carry the same message. The gesture ARM
RAISE however is an example for an ambiguous gesture because it is used
to solicit grooming but also to calm and appease an anxious conspecific,
thereby communicating and embodying different messages across contexts.
This cognitive approach to gestural signaling was continued and expanded
by Tomasello and his research group, who provided the first systematic
evidence that gestural skills of apes are far more complex and sophisticated
than their vocal abilities (Call & Tomasello, 2007). By creating the first
comprehensive database on gestural signaling of the four great ape species
and one smaller ape (siamangs), they showed that apes
•

use open-ended, multifaceted gestural repertoires, including speciesdistinctive and species-indistinctive gestures, whose meaning and usage
has to be learned;

Gestural Communication in Nonhuman Species

•

•

7

use gestures as flexibly produced intentional strategies such as (i)
recipient specificity, (ii) persistence to the goal (e.g., repetition of a
gestures or use of a different one until the goal has been achieved), (iii)
means-ends dissociation (see paragraph above), and (iv) adjustment to
audience effects such as (1) adaption of signal category to the attentional
states of recipient and (2) locomoting in the visual field of the recipient
before producing a visual gesture; and
develop group-specific traditions of gesture, implying that underlying
social learning processes are involved.

Tomasello recently emphasized the impact of these findings on scenarios of
language evolution by noting: “In all, I personally do not see how anyone can
doubt that ape gestures—in all of their flexibility and sensitivity to the attention of the other—and not ape vocalizations—in all of their inflexibility and
ignoring of others—are the original font from which the richness and complexities of human communication and language have flowed” (Tomasello,
2008, p. 55).
CURRENT DEVELOPMENTS AND FUTURE AVENUES
In recent years, the number of publications reporting new and fascinating
results about the gestural skills of primates has increased impressively (for
an overview see Pika & Liebal, 2012a). Although scientific investigations still
disproportionally concentrate on gestural skills of (i) common chimpanzees
(P. troglodytes); (ii) primates living in captive environments; and (iii) signalers
of gestural interactions rather than recipients or both, a considerable amount
of research interest has now shifted toward the gestural abilities of species
in natural environments (e.g., Genty, Breuer, Hobaiter, & Byrne, 2009; Pika &
Mitani, 2006; Roberts, Vick, & Buchanan-Smith, 2012), as well as monkeys
(e.g., Maestripieri, 2005; Meguerditchian & Vauclair, 2006).
In addition, current trends and debates concern
•
•
•
•

the origins of gestures;
gestural usage;
the neural substrates of gestural signaling; and
the application of new methods.

The most intriguing research avenue toward an in-depth understanding of
the evolutionary pressures acting upon gestural systems, however, concerns
systematic investigations into the cognitive complexity underlying the visual
and tactile signals of nonprimate taxa (Pika & Bugnyar, 2011). Although in the
past century, ethologists and ornithologists had been especially fascinated

8

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

with courtship and threat displays of birds (Huxley, 1923; Lorenz, 1939), and
fish (Dominey, 1983), these signals were mainly interpreted as fixed action
patterns rather than complex cognitive means.
Recently, however, Kaplan (2011) reported that Australian magpies (Gymnorhina tibicen), which are highly social and cooperative songbirds, use a distinct posture to “point out” the position of a predator to their conspecifics.
In addition, Pika and Bugnyar (2011) investigated the gestural behavior of
another cooperative songbird species, ravens (Corvus corax) in their natural
communicative interactions in the wild. They showed that ravens use gestures to refer to outside entities and to share attention with conspecifics. Since
referential gestural signals had so far been only described in humans and
great apes (for an overview see Pika, 2012), it seems that our understanding of gestural systems is only at its beginning and that future research will
provide a viable base from which we may draw informed inferences about
gestures and its importance for language origins.
ACKNOWLEDGMENTS
I am grateful to Wolfgang Wickler for fruitful discussions and Sue Anne
Zollinger for constructive help with editing the essay. This project was
supported by a Sofja Kovalevskaja Award of the Alexander von Humboldt
Foundation.
REFERENCES
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Call, J., & Tomasello, M. (2007). The gestural communication of chimpanzees (Pan
troglodytes). In J. Call & M. Tomasello (Eds.), The gestural communication of apes and
monkeys (pp. 17–40). Mahwah, NY: Lawrence Erlbaum Associates.
Diller, K. C., & Cann, R. L. (2009). Evidence against a genetic-based revolution
in language 50,000 years ago. In R. Botha & C. Knight (Eds.), The cradle of
language—studies in the evolution of language (pp. 135–149). Oxford, NY: Oxford
University Press.
Dominey, W. J. (1983). Mobbing in colonially nesting fishes, especially the bluegill,
Lepomis macrochirus. Copeia, 1983, 1086–1088.
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Gardner, R. A., & Gardner, B. T. (1969). Teaching sign language to a chimpanzee.
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Genty, E., Breuer, T., Hobaiter, C., & Byrne, R. W. (2009). Gestural communication of
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Jerison (Eds.), Evolution, brain and behavior: Persistent problems (pp. 115–122). New
York, NY: John Wiley & Sons, Inc.
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who has it, and how did it evolve? Science, 298, 1568–1579.
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Krause, J., Lalueza-Fox, C., Orlando, L., Enard, W., Green, R. E., Burbano, H. A., … ,
Pääbo, S. (2007). The derived FOXP2 variant of modern humans was shared with
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Lai, C. S., Fischer, S. E., Hurst, J. A., Vargha-Khadem, F., & Monaco, A. P. (2001).
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Lorenz, K. (1939). Vergleichendes über die Balz der Schwimmenten. Journal für
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Lovejoy, C. O. (2009). Reexamining human origins in light of Ardipithecus ramidus.
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Maestripieri, D. (2005). Gestural communication in three species of macaques
(Macaca mulatta, M. nemestrina, M. arctoides). Use of signals in relation to dominance and social context. Gesture, 5, 57–73.
Marler, P. (1970). Birdsong and speech development: Could there be parallels? American Scientist, 58, 669–673.
McNeill, D. (2012). How language began. Gesture and speech in human evolution. Cambridge, England: Cambridge University Press.
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Pika, S. (2012). The case of referential gestural signaling. Where next? Communicative
& Integrative Biology, 5, 1–5.
Pika, S., & Bugnyar, T. (2011). The use of referential gestures in ravens (Corvus corax)
in the wild. Nature Communications, 2, 1–5.
Pika, S., & Liebal, K. (2012a). Developments in primate gesture research. Amsterdam,
The Netherlands: John Benjamins Publishing Company.
Pika, S., & Liebal, K. (2012b). Introduction: Developments in primate gesture
research. In S. Pika & K. Liebal (Eds.), Developments in primate gesture research (pp.
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Plooij, F. X. (1978). Some basic traits of language in wild chimpanzees?. In A. Lock
(Ed.), Action, gesture, and symbol: The emergence of language (pp. 111–131). New York,
NY: Academic Press.
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Roberts, A. I., Vick, S.-J., & Buchanan-Smith, H. M. (2012). Usage and comprehension
of manual gestures in wild chimpanzees. Animal Behaviour, 84, 459–470.
Rumbaugh, D. M., Gill, T. V., & von Glaserfeld, E. C. (1973). Reading and sentence
completion by a chimpanzee (Pan). Science, 182, 731–733.
Savage-Rumbaugh, E. S. (1979). Symbolic communication—its origins and early
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Savage-Rumbaugh, E. S., Rumbaugh, D. M., & McDonald, K. (1985). Language learning in two species of apes. Neuroscience and Biobehavioral Reviews, 9, 653–656.
Seyfarth, R. M. (2005). Continuities in vocal communication argue against a gestural
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Tomasello, M. (2008). Origins of human communications. Cambridge, MA: MIT Press.

SIMONE PIKA SHORT BIOGRAPHY
Simone Pika is the head of the Humboldt Research Group on “Comparative Gestural Signalling” at the Max Planck Institute for Ornithology in
Seewiesen, Germany. Her PhD at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, focused on gestural complexity and
underlying cognitive skills of great apes. She held research fellowships at the
University of Alberta, Canada, and the University of St. Andrews, Scotland,
and a post as Assistant Professor at the University of Manchester, UK.

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Gestural Communication in
Nonhuman Species
SIMONE PIKA

Abstract
The evolution of language remains one of science’s greatest mysteries. Although first
comparative investigations into language origins focused on vocal abilities of nonhuman animals, especially primates, the number of publications reporting new and
fascinating results about gestural skills of nonhuman animals has notably increased.
To get a better insight in this intriguing scientific field, the present essay will provide a brief overview of its history and will then pinpoint current trends and future
avenues.

INTRODUCTION
Human language forms such an exception among the behaviors of animals that it has often been used to define what it means to “be human.”
Although there is still an ongoing debate concerning the definition of language, many theorists would agree that it embodies several communicative
modalities—the auditory, tactile, and visual one—and is used referentially to
direct and influence the attentional and mental states of others. The earliest
manifestations of the potent urge to engage in communicative activities can
already be observed in human children around the age of 9–12 months,
when they start to use gestures, sounds, and/or a combination of both to
obtain objects, and affect the thinking and behavior of other individuals.
This behavior is so different from the vocal and gestural languages of other
animals that it calls for an evolutionary investigation (Botha & Knight, 2009).
Why do only humans have language?
Theories of the origins of language must account for the extremely short
phylogenetic time available for the evolution of this highly sophisticated
behavior. Some suggest that our hominin ancestors did not possess the
anatomical and neural prerequisites to produce spoken language, at least
until very recently (Lieberman, 2002; although this view is challenged
by Fitch (2009). A recent study by Krause et al. (2007) shows that our
Emerging Trends in the Social and Behavioral Sciences. Edited by Robert Scott and Stephen Kosslyn.
© 2015 John Wiley & Sons, Inc. ISBN 978-1-118-90077-2.

1

2

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

closest extinct relatives, the Neanderthals, share with modern humans two
evolutionary changes in FOXP2, a gene that has been implicated in the development of speech and language (Lai, Fischer, Hurst, Vargha-Khadem, &
Monaco, 2001). Diller and Cann (2009) suggest a gradual coevolution of
language and the complex brain structures necessary for speech and fully
modern language, with the mutations in FOXP2 occurring some 1.8 million
years ago, when human brains doubled in size from the 450 cc brains of
chimpanzee (Pan troglodytes) and australopithecines to the 1350 cc brains of
modern humans. This time period is relatively short and clearly insufficient
for the evolution of the entire cognitive apparatus required for normally
developed linguistic behavior, suggesting that many of the neural, anatomical, and cognitive components required for language processing must be
substantially older, having evolved in the primate lineage long before the
advent of speech in modern humans.
THE COMPARATIVE APPROACH
A powerful approach to problems of language evolution is provided by the
comparative method, which uses empirical data from living species to draw
detailed inferences about the behavior of extinct ancestors. Although scholars interested in the evolution of language have often ignored comparative
data altogether or focused narrowly on only data from nonhuman primates
(hereafter primates), recent developments in neuroscience, molecular biology, and developmental biology indicate that many aspects of neural and
developmental function are highly conserved, encouraging the extension
of the comparative method to all vertebrates (and perhaps beyond, Hauser,
Chomsky, & Fitch, 2002). Furthermore, recent archaeological evidence
suggests, that early hominins and extant apes are remarkably divergent in
many anatomical features (e.g., dentition and feet; Lovejoy, 2009). Thus, in
order to reconstruct the changes that paved the way for language to evolve,
we should consider the likely adaptations of early hominins generally, rather
than only with specific reference to living chimpanzees (Lovejoy, 2009).
Detailed insight into the communicative abilities of our closest phylogenetic
relatives, the nonhuman primates, can thus by both homology and analogy,
help in reconstructing the behavior of the last common ancestor of Pan
and Homo and perhaps some aspect of early hominin behavior. Examples
of convergent evolution in distant related species can provide clues to the
types of problems that particular morphological or behavioral mechanisms
are “designed” to solve (Gould, 1976).
Furthermore, in order to claim that particular components of human language are unique to humans, data indicating that no other animal has this
particular trait is required.

Gestural Communication in Nonhuman Species

3

As we tend to associate language first with sound rather than movement,
the majority of comparative research in relation to language origins focused
on vocalizations (Marler, 1970; Seyfarth, 2005). However, speech consists
of over 100 acoustically unique phones, commonly combined into rapid
sequences, which serve as the main carriers of meaning. Thus the ability
to produce speech relies heavily on fine, rapid and voluntarily produced
motor movements synchronized with cognitive activity. In addition, McNeill
recently stated “that language could not have come into existence without
gesture” (McNeill, 2012, p. 59). To understand the evolutionary precursors of
human language and the linkage between speech and gesture, we therefore
also need to gain a profound knowledge of gestural forms, their usage and
their function in nonhuman animals. The present essay aims to provide a
brief overview of the history of this scientific field and will then focus on
current trends and future avenues in this exciting research domain.
BRIEF HISTORY OF COMPARATIVE GESTURAL RESEARCH
Earliest comparative studies on gestural skills were mainly descriptive
and focused on our closest living relatives, the great apes. Ladygina-Kohts
(1935) for instance compared the expressive behavior of a chimpanzee and
a human child and concluded that the initial language of both species,
consisting of gestures, facial expressions and vocalizations, is quite similar. Since attempts to teach human speech to chimpanzees had failed,
researchers tried to overcome great apes’ difficulties in speech production
by switching to the manual modality. The first language projects centered
on three chimpanzee females, Sara, Lana, and Washoe, and used different
methodologies to communicate: (i) three-dimensional plastic pieces; (ii)
two-dimensional geometric designs; and (iii) manual signs (Gardner &
Gardner, 1969; Premack & Premack, 1972; Rumbaugh, Gill, & von Glaserfeld, 1973). One of the most successful studies was the sign language
project carried out by the Gardners (1969), who raised a chimpanzee female,
Washoe, in a house trailer exposing her to human caretakers communicating
via American Sign Language (ASL) only. Washoe learned to use over a
hundred of signs in appropriate ways, invented new signs and was also
able to modulate taught signs in new purposeful ways. In addition, she
formed sequences of signs, which mainly followed two principles: (i) more
urgency ⇒ more signs and (ii) Addressee–Action–Nonaddressee (McNeill,
2012). The Addressee (or “donor”)–Action–Nonaddressee (or “recipient”
and always Washoe) sequence represents an iconic model by depicting
the desired result. However, contrary to human language, which is most
notably used to communicate and interact in bubbles and hallucinations of
thought, about today but also yesterday and tomorrow, Washoe’s sequences

4

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

mainly concerned objects and events in the here and now and communicated specific demands to meet specific wants with herself as beneficiary
(McNeill, 2012). Although this and other ape language projects seemed
to suggest that apes are able to converse with human caretakers via true
symbols, there were several criticisms: First, the apes may have only learned
basic conditioned associations between various food items and symbols
instead of true symbolic communication (Savage-Rumbaugh, 1979). Second,
the methods applied in sign-language studies and all other ape language
projects (e.g. Premack & Premack, 1972; Rumbaugh et al., 1973) differed
significantly from language acquisition in normally developing human children. Human children acquire linguistic symbols through joint attentional
frames that involve the intertwining of both linguistic and gestural means
and actions between two or more individuals, starting very early with
simple rule-oriented turn-taking games such as peek-a-boo. Furthermore, in
these social situations, children do not simply learn words concerning food
or object names only or sentence structure, but also “how to be” and “how
to interact” in a wide range of settings. Even more crucially, they start to
understand caretakers’ specific communicative intentions as expressed in
an utterance.
Contrary to this learning environment, language-trained apes were typically taught to produce a symbol when a food item or object was held up
in front of them or when a desired activity was withheld, assuming that
comprehension would follow production naturally. For instance, if Washoe
wanted a drink from the experimenter, she was required to sign “drink” in
order to obtain it; if she wanted to go outdoors she was required to sign
“open” before she would be allowed to leave, and so on. Contrary, just using
a pointing gesture to the drink or the door was not considered an acceptable means of communicating the same intent. Similarly, if Sarah wanted an
apple that was in front of her, she was only allowed to use a very limited communicative mean: placing the proper plastic chip on the tray to “name” the
apple. If Lana wanted M&Ms in the dispenser, she had to press the buttons
on the keyboard “Please machine give M&M.” Terrace (1979) thus argued
that the apes in these scenarios sign only as a “way out,” suggesting that
their symbol production and comprehension are not reflective of comparable levels of cognitive comprehension in normally developing children.
Furthermore, McNeill (2012) proposed that not only differences in nonhuman primates’ mouth-anatomy but the lack of a thought-language-hand link
brain to orchestrate mouth-part movements are the reason why nonhuman
primates have not developed language.
In response to these criticisms, Savage-Rumbaugh and colleagues aimed
to develop succinct, systematic procedures to push apes past the initial
stage of using associations instrumentally and to enable true symbolic

Gestural Communication in Nonhuman Species

5

comprehension and usage (Savage-Rumbaugh, 1979). They used again
the electronically activated, computer-interfaced keyboard invented for
the Lana project. The keys represent noniconic graphic symbols of one
of more elements of nine basic geometric patterns, analogous to letters
of the alphabet. The first teaching sessions circled around continuous
one-to-one contact of four chimpanzees with a human teacher, encouraging the communicative and cognitive abilities of the apes by presenting
and naming single nonfood items. After 4 months however, not a single
chimpanzee showed any sign of learning names for the training objects.
Instead of focusing on the task itself, the apes directed their main efforts and
attention toward the experimenter to influence his decision to hand out a
reward AFTER the trial. Savage-Rumbaugh (1979) therefore adjusted their
experimental procedure by removing the decision-making process from the
experimenter and by giving him the role of a helper rather than a judge
of individual’s performance. Although two of the chimpanzees, Sherman
and Austin, learned to use the keyboard’s symbols to request food, trips
out of doors, blankets, and behaviors such as grooming and tickling, the
biggest success of this scientific adventure originated by unintentionally
matching the language learning process in normally developing human
children (Savage-Rumbaugh, Rumbaugh, & McDonald, 1985). At that time,
Savage-Rumbaugh et al. (1985) had also started working with a wild-caught
adult bonobo (Pan paniscus) female, Matata, exposing her to the same
established experimental procedure and showing her to use the keyboard
to request foods, objects and certain behaviors. Matata, however, while not
very successful in symbol acquisition herself, had a 6 months old stepson
Kanzi, who did not receive any particular training but was always with
Matata during the training sessions. At the age of 12 months, he started
to show a playful interest in the keyboard and at the age of 2.5 years he
switched to selecting specific symbols. Even more surprising, however, he
combined specific keys with gestures, for instance he would produce the
lexigram for “ball” and then gesture toward his ball to request that the ball
was brought to him. Alternatively, he pressed the lexigram for “tomatoes,”
which represented a distinct location in the enclosure and gestured in the
direction of it.
Furthermore, Kanzi started to request food via lexigrams and was also able
to name foods he had observed Matata learning. His behavior thus showed
that he had acquired lexigrams spontaneously by observing his mother. In
addition, he had learned many of the lexigrams his mother had not and was
able to understand the symbols bidirectionally, which means that he was able
to produce and to comprehend them without any specific training. The subsequent procedure used with Kanzi was therefore to keep the exposure of
lexigrams as natural as possible. His human caretakers used symbols when

6

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

communicating, encouraged him to do so as well and thus functioned as
communicative models. In addition, as the enclosure consisted of 55 acres
of forest, Kanzi’s food was dispersed daily throughout the forest, enabling
him to search for and discover it in a more natural way. In many ways his
early vocabulary matched the early vocabularies of human children, including names for individuals, labels for common objects, words for actions, locations and properties. It included even a few function words such as “no”
and “yes.” However, similar to the apes in the sign-language projects, Kanzi
mainly communicated about objects and events (i) in the here and now and
(ii) benefiting merely his own goals and desires.
In parallel, researchers also had started to investigate the behavior of
primates in their natural environments, including detailed descriptions
of communicative signals such as vocalizations, facial expressions, and
gestures. However, the first step toward an understanding of the cognitive
complexity underlying the natural communication abilities of great apes
was done by Plooij (1978) studying the ontogeny of gestural signals in
chimpanzees at Gombe, Tanzania. He applied methods of Speech Acts
Theory and parameters used in analyses of intentional behavior in human
prelinguistic human children. Plooij showed that gestures of chimpanzees
resemble those of prelinguistic human children in some important ways:
They are (i) characterized by their flexible relation between means and
ends (means-ends dissociation) and (ii) used to attract and redirect attention. Means-ends dissociation suggests that individuals are able to use (i)
synonymous signals/gestures to achieve a certain outcome/goal and (ii)
ambiguous gestures for different outcomes/goals (Pika & Liebal, 2012b).
Examples for synonymous gestures are the gestures TOUCH and REACH OUT
ARM, which are both used by chimpanzee infants to communicate to the
mother to be picked up and thus carry the same message. The gesture ARM
RAISE however is an example for an ambiguous gesture because it is used
to solicit grooming but also to calm and appease an anxious conspecific,
thereby communicating and embodying different messages across contexts.
This cognitive approach to gestural signaling was continued and expanded
by Tomasello and his research group, who provided the first systematic
evidence that gestural skills of apes are far more complex and sophisticated
than their vocal abilities (Call & Tomasello, 2007). By creating the first
comprehensive database on gestural signaling of the four great ape species
and one smaller ape (siamangs), they showed that apes
•

use open-ended, multifaceted gestural repertoires, including speciesdistinctive and species-indistinctive gestures, whose meaning and usage
has to be learned;

Gestural Communication in Nonhuman Species

•

•

7

use gestures as flexibly produced intentional strategies such as (i)
recipient specificity, (ii) persistence to the goal (e.g., repetition of a
gestures or use of a different one until the goal has been achieved), (iii)
means-ends dissociation (see paragraph above), and (iv) adjustment to
audience effects such as (1) adaption of signal category to the attentional
states of recipient and (2) locomoting in the visual field of the recipient
before producing a visual gesture; and
develop group-specific traditions of gesture, implying that underlying
social learning processes are involved.

Tomasello recently emphasized the impact of these findings on scenarios of
language evolution by noting: “In all, I personally do not see how anyone can
doubt that ape gestures—in all of their flexibility and sensitivity to the attention of the other—and not ape vocalizations—in all of their inflexibility and
ignoring of others—are the original font from which the richness and complexities of human communication and language have flowed” (Tomasello,
2008, p. 55).
CURRENT DEVELOPMENTS AND FUTURE AVENUES
In recent years, the number of publications reporting new and fascinating
results about the gestural skills of primates has increased impressively (for
an overview see Pika & Liebal, 2012a). Although scientific investigations still
disproportionally concentrate on gestural skills of (i) common chimpanzees
(P. troglodytes); (ii) primates living in captive environments; and (iii) signalers
of gestural interactions rather than recipients or both, a considerable amount
of research interest has now shifted toward the gestural abilities of species
in natural environments (e.g., Genty, Breuer, Hobaiter, & Byrne, 2009; Pika &
Mitani, 2006; Roberts, Vick, & Buchanan-Smith, 2012), as well as monkeys
(e.g., Maestripieri, 2005; Meguerditchian & Vauclair, 2006).
In addition, current trends and debates concern
•
•
•
•

the origins of gestures;
gestural usage;
the neural substrates of gestural signaling; and
the application of new methods.

The most intriguing research avenue toward an in-depth understanding of
the evolutionary pressures acting upon gestural systems, however, concerns
systematic investigations into the cognitive complexity underlying the visual
and tactile signals of nonprimate taxa (Pika & Bugnyar, 2011). Although in the
past century, ethologists and ornithologists had been especially fascinated

8

EMERGING TRENDS IN THE SOCIAL AND BEHAVIORAL SCIENCES

with courtship and threat displays of birds (Huxley, 1923; Lorenz, 1939), and
fish (Dominey, 1983), these signals were mainly interpreted as fixed action
patterns rather than complex cognitive means.
Recently, however, Kaplan (2011) reported that Australian magpies (Gymnorhina tibicen), which are highly social and cooperative songbirds, use a distinct posture to “point out” the position of a predator to their conspecifics.
In addition, Pika and Bugnyar (2011) investigated the gestural behavior of
another cooperative songbird species, ravens (Corvus corax) in their natural
communicative interactions in the wild. They showed that ravens use gestures to refer to outside entities and to share attention with conspecifics. Since
referential gestural signals had so far been only described in humans and
great apes (for an overview see Pika, 2012), it seems that our understanding of gestural systems is only at its beginning and that future research will
provide a viable base from which we may draw informed inferences about
gestures and its importance for language origins.
ACKNOWLEDGMENTS
I am grateful to Wolfgang Wickler for fruitful discussions and Sue Anne
Zollinger for constructive help with editing the essay. This project was
supported by a Sofja Kovalevskaja Award of the Alexander von Humboldt
Foundation.
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SIMONE PIKA SHORT BIOGRAPHY
Simone Pika is the head of the Humboldt Research Group on “Comparative Gestural Signalling” at the Max Planck Institute for Ornithology in
Seewiesen, Germany. Her PhD at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, focused on gestural complexity and
underlying cognitive skills of great apes. She held research fellowships at the
University of Alberta, Canada, and the University of St. Andrews, Scotland,
and a post as Assistant Professor at the University of Manchester, UK.

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