by
Iain
Davidson, University of New England. (April 1990)
Kanzi, a
bonobo or pygmy chimpanzee, can comprehend spoken English. He may, also, be able to utter some sounds
that should be recognised as words.
This startling result of research by Sue Savage-Rumbaugh and her team at
the Language Research Centre, Georgia convinced some hardened sceptics at a
recent conference on "Tools, Language and Intelligence: evolutionary
implications". Each of the
participants at the conference will draw different conclusions from this, but
there was a consensus that the new data on chimpanzees, both from
Savage-Rumbaugh, and from field studies by Christophe Boesch and synthesis by
Bill McGrew, go even further than previous ape studies in making us question
the nature of human uniqueness. In this
summary of the events of the conference I want to record my personal
impressions, and some of the first conclusions I draw.
The
conference was organised in Cascais, Portugal, for the Wenner-Gren Foundation
for Anthropological Research by Tim Ingold and Kathleen Gibson, and took place
between 16 and 24 March, 1990. The
participants were from various disciplines: archaeology (Davidson, Graves,
Hewes, Toth, Wynn); primatology (Boesch, McGrew); social anthropology (Ingold,
Silverman); developmental psychology (Goldin-Meadow, Greenfield, Kempler;
Langer, Lock); biological anthropology (Gibson, Parker); neurology (Calvin) and
palaeoneurology (Falk); cognitive science (Lieberman); experimental psychology
(Kendon, Visalberghi); and zoology (Snowdon).
There were experts on gesture (Goldin-Meadow, Kendon) and on speech
production (Lieberman); on stone tools (Toth, Wynn) and on Alzheimer's disease
(Kempler). But despite the diversity,
in the characteristic mode of Wenner-Gren conferences, the dialogue across
disciplinary boundaries was outstanding.
We may not have founded a new discipline, but we all know much more
about the relevant parts of others. As
Andy Lock put it: "there is something different about getting it from the
mouth of a horse, and not the other end of a cow".
THE
DEVELOPMENTAL PSYCHOLOGY OF LANGUAGE
It is
clear that language is acquired and not innate: it gets there not in the genes
but by guided reinvention, as Lock calls it.
Pat Greenfield and Jonas Langer both presented data and theory on the
earliest stages of cognitive development in human infants. Greenfield demonstrated that the earliest
stages of the manipulation of objects and of vocal utterances should be
considered homologous, not merely analogous.
The issue, then, is how and why they diverge. For Langer, the essential disjunction, at this early stage of the
ontogeny of modern humans, is that the "production" of cognition
precedes its comprehension, while in language development, comprehension
precedes production. Indeed, it can be
argued that the production of language is what makes the comprehension of
cognition possible. In simple language,
and stripped of the assumptions involved in referring to perceptions of the world
as cognitive, I take this to imply that young children explore their world
through sounds and objects in similar ways.
But at some stage these explorations take different paths. No sentient organism could survive without
"production" of cognition in this sense, so it should not surprise us
that it appears early in human development.
Two major
points converge on these observations.
First that it may be that the combination of cognitive production and
linguistic comprehension leads to cognitive comprehension. Simplistically, we know what we know because
we know what we are talking about.
Secondly, the comprehension that vocal utterances can communicate
necessarily involves a relationship between persons, while object manipulating
only involve the person (or infant) and the object. As Sue Savage-Rumbaugh indicated, manipulation of objects may
only involve the individual and the tools.
But in manipulation of the object the individual will invent gestures
about the use of tools. Viewing
videotapes presented by Christophe Boesch of chimpanzees in the Tai forest
cracking nuts, and by Susan Goldin-Meadow of deaf children of hearing parents
using invented gestures to communicate, we saw "language invented in front
of our eyes" in Savage-Rumbaugh's terms.
In each case, the gestures were directly within the contingency of
object manipulation, real or imaginary.
In
archaeology there are two approaches to evolutionary issues that derive from
developmental studies. The first takes
a sequence of ontogenetic development and matches it to some sequence of
changes described by archaeologists.
Lock pointed out the pitfalls of any argument that is so crudely
recapitulationist, and I pointed out that many of the tales told by archaeologists
have not taken into account that language is an issue, and therefore have
assumed greater language abilities in hominids that we can reasonably
infer. Sequence matching therefore may
be unrelated to reasonable interpretation of the archaeological record.
The second
approach is to recognise from the guidedness of the reinvention of language
that the context of learning is so fundamental that only when such a context
had emerged could language be invented.
Tim Ingold stressed how important it is to distinguish different senses
of the concept "social", as this context of learning is generally
described by the word (e.g. White 1985).
Social relations of the type commonly studied by social anthropologist,
like Ingold, are defined by the recognition in language of kinship relationship
beyond those of immediate parenthood.
Clearly these could not have emerged before language itself. But social interactions between individuals,
particularly between mother and infant might easily have emerged as continuing
relationships in any altricial species.
The context for learning, as seen in the chimpanzees of the Tai forest,
may occur among wild-living primates.
The question becomes how such a context came to include language
comprehension and production. Adam
Kendon stressed links between vocal and gestural pantomime as a means for the
emergence of "displaced reference", a key notion given rather little
prominence at the conference, despite its formulation as the issue by Davidson
and Noble (1989; Noble & Davidson 1990).
THE
RELEVANCE OF STUDIES OF NON-HUMAN PRIMATES
The
extraordinary discovery of Kanzi's language comprehension, contrasted with the
more general inability of chimpanzees to comprehend, must be understood in this
context. Susan Goldin-Meadow commented
on the contrast between the learning environments of the deaf children she
studied and of the chimpanzees in Sue Savage-Rumbaugh's project. By not encouraging the deaf children to
learn sign language, the parents were providing a less complete opportunity for
development than a hearing child would get from hearing parents. Kanzi, by contrast, has had an enriched
environment, for language learning, though as Christophe Boesch pointed out,
not for all aspects of learning as a chimpanzee. We might, therefore, attribute Kanzi's learning to the enrichment
of the developmental process.
Chimpanzees
in the wild, in Christophe Boesch's study, also learn from their caregivers,
particularly in the processing of nuts of Panda and Coula trees. The caregivers achieved this by leaving
hammers (often stone hammers) on an anvil, leaving nuts on an anvil, or placing
both nut and hammer on an anvil. Such
behaviours would be called "scaffolding" by developmental
psychologists such as Greenfield. On
two occasions, chimpanzees demonstrated to their infants how to solve problems
they could not overcome by themselves.
Such abilities are far in excess of those of even clever monkeys, such
as South American Cebus, as shown by Elisabetta Visalberghi in her presentation
and another video. In these capuchin monkeys
some problem solving was possible, but not consistently across the studied
individuals. There seemed to be no good
argument that Cebus can learn by imitation.
The lesson
of this is that there are differences between species, particularly in their abilities
to learn. Kathleen Gibson, one of the
organisers, repeatedly stated that "every time I learnt something unique
about humans, it wasn't unique".
But to emphasise this at the expense of searching for differences is to
run the risk of thinking that chimpanzees are the same as humans. I do not think any of us really believed
that. Bill McGrew came closest to
expressing this view, in an attempt to encourage further thought and
research. He pointed out that none of
the field studies of chimpanzees of the last 20 years has concentrated on
vocalisations or other possible means of communication, despite anecdotic
evidence that chimpanzee behaviour sometimes seems to require it. I am sure that this conference will
stimulate such work on vocalistations and gestures. Chuck Snowdon reviewed the literature on language-like abilities
among other species, arguing that we can sometimes learn as much from
convergence as from diverging evolution.
He concluded that, despite the claim for generative grammar in the
chickadee, none of the claims for symbolic communication are convincing.
Chimpanzees
are clever, but they are not as clever as humans. The central problem of all chimpanzee studies is that their
human-like abilities in the wild seem to be less thatn their abilities in the
laboratory. In a developmental
framework we may attribute this to the stimulus provided by human
caregivers. The issue for
archaeologists seems to be that which Noble and I have identified: how could
the greater abilities of humans have emerged in human evolution without the
prior existence of such tutors?
LANGUAGE
AND THE BRAIN
This
begins to sound like an evolutionary question.
The difficulty that many people, some anthropologists included, seem to
have with evolutionary arguments is that they cannot divest themselves of
notions of progress. They seem to
believe that there are positive pressures creating variability to permit new
functions. Thus the social position
would be caricatured as suggesting that once the relationship of caregiving of
infants by adults came into being, language would somehow develop in the
interaction. Clearly it cannot be as
simple as that.
Similar
arguments, with perhaps more reason to be criticised by evolutionary theorists,
abound in popular perceptions of the brain and its expansion during the course
of hominid evolution. One of the most
robust data of the fossil record is that hominid brain size has tended to
increase through time. The rate of
increase for Homo species seems to be greater than that of Australopithecus
species, and greater than any documented increase for any other genus. Falk additionally reported that statistical
analysis of brain size estimates, where this is possible, suggests no saltations
in brain size in the genus Homo.
It is very
tempting to suggest that the brain expanded to allow language or because of
language. But the mechanism can never
have been so simple, or so mystical.
Dean Falk summarised the data on brain expansion, and drew attention to
gender differences in the dominance of hemispheric lateralisation. Gender was not an issue pursued at any
length in the conference. Bill Calvin
proposed his mechanism for brain expansion: selection for redundancy in the
circuitry of the brain through increased advantage from accurate and powerful
throwing. This seems to Noble and
myself (Davidson & Noble 1989; Noble & Davidson 1989) the currently
most plausible argument, though I was more sceptical of Calvin's adoption of
the "frisbee" theory of the use of the handaxe, until we threw the
specimen which Nick Toth made for the conference delegates.
One of the
most interesting suggestions at the conference was by Kathleen Gibson, who
suggested that absolute brain size was really the critical variable. Other mammals with large brain size are
claimed to have complex behaviours associated with brain function: particularly
elephants and dolphins. Rather as
Savage-Rumbaugh postulated that syntax is an inevitable result of the
organisation of mor complex communicative utterances, so Gibson suggested that
complexity of the organisation of the brain was a result of the increase of
information processing made possible and necessary by the expanding brain.
Brains are
rather difficult to understand for those of us who are not specialists. As people, we tend to act as if it makes
sense to talk of the brain "doing something", as if there were a
little person, a homunculus, in there pulling strings, and turning
handles. The reality is much more complex. But in our efforts to understand persons we
tend to seek explanation either by moving outside the person into the social
environment in which persons operate, or retreating into the body, and
especially the brain as if it operates persons (Noble & Davidson n.d.). In reality the person is we are interested
in taking into account its interactions both with society and the brain, but
the complexities of each context are so difficult that it is easy to
concentrate on one or the other. Maybe
after Social Archaeology and The Archaeology of Mind it would be appropriate to
have an "Archaeology of Persons".
We managed
to avoid homunculi, though Broca's Area became so important in some discussions
that it was tempting to suggest that that was where the homunculus lives. Falk has demonstrated that an area that
corresponds to Broca's Area can be identified on endocasts of Homo habilis, the
question becomes what its significance is.
The plasticity of the brain, to recover from injury, as discussed in Dan
Kempler's paper, together with the difficult of identifying precisely where key
regions such as Broca's Area are, suggests that the model of the brain as
independant organism cannot work.
The brain
seems to be an organ that receives stimuli and responds to them. The particular responses of an adult
organism may be a limited set of all of the possible responses that that
organism is capable of, and it is the developmental process that establishes
those limitations. There is essentially
a difference between what Kanzi can do and what other apes do do and these
differences result from the different developmental environments they have
experienced. The brain has unrevealed
capacity, and that contributes to the variability in the behaviour of
organisms. But we should not take that
to licence interpretations of the archaeological record which assume that
capacities unrevealed in the surviving record would be identifiable in the
record that has not survived. In
investigating the evolutionary emergence of novel behaviours, the behaviours,
whatever they are, that distinguish humans from other species, we cannot rely
on arguments that the Olduvai hominids painted "Sunflowers" or typed
"The Tempest, but the evidence has just not survived. That sort of story telling sounds altogether
too post-processual, and I assume we are more serious about our science than
that. The real problem, as Bill McGrew
identified, is to develop methodology for the interpretation of the
archaeological record which will allow us to identify the features of the
emergence of such evanescent yet fundamental behaviours as language.
ARCHAEOLOGY
AND LANGUAGE
There were
four papers by archaeologists at the conference: Gordon Hewes, whose gestural origin theory was one of the early
contributions to recent work on language origins; Nick Toth, who spoke from the
point of view of his work on replication of stone artefacts; Thomas Wynn,
pioneer of application of Piagettian analysis to the individual artefacts of
the Lower Palaeolithic; and myself.
There was general agreement that stone tools do not yield obvious
information about language competence or performance. Toth and Schick, however, made the observation that as hominid
populations moved out of Africa for the first time they seemed to lose the
technology of the Acheulean. They
suggested that this was a result of difficulty in locating suitable raw
material supplies, together with a short term mode of communicating the
necessary techniques. In other words,
when the first hominids got to a new environment, the difficulty of locating
suitable raw material was enough to make them forget how to make handaxes. And theymay not have reinvented them. Rather, the Acheulean only spread later when
new populations leaving Africa would have had the advantage of interaction with
existing hominids to learn suitable stone supplies. I have advanced a similar argument about the first colonisation
of Australia, rather later in date, by fully modern humans. Stone raw material supply is a major
variable in understanding the nature of stone industries.
Wynn was
concerned, in his early work, with the operational skills necessary to
manufacture artefacts. By seeking in
stone artefacts indications of the necessary spatial competence to manufacture
them, Wynn succeeded in identifying some aspects of the developmental stage
that the manufacturers must have reached.
This operationalising of the concepts defined by Piaget seems to me far
more satisfactory than the published attempts (e.g. by Parker 1985) to match
the sequence of stages defined by Piaget with some sequence of stages of human
evolution taken from the standard archaeological account. Nevertheless, it leaves hominids at stages
of childhood which seems to describe them as incomplete humans, rather than
complete hominids.
A serious
problem with Wynn's approach, however, is the degree of necessity in the
operations he describes. Certainly
rotation of the core is necessary to manufacture a biface in one sequence (or
chain) of action, but was there such a sequence? My paper with Noble for the conference addressed this sort of
issue directly, by pointing to what we call the "finished artefact
fallacy". This is the, often
subconscious, attitude which sees every product of prehistoric people as
intentional. The typologies by which we
describe stone industries are absolutely wedded to this position. Elaboration of tool types, defined as flakes
with modified or retouched edges, is a conceit of the classifiers rather than
necessarily of the manufacturers. And
in our formulation of this as a problem the question goes straight to the issue
of language and its recognition in the archaeological record. The question is about intention, time-depth
of intention and hence displacement.
Noble and
I have been tempted in our published and unpublished papers to deny any
intention at all to all non-human animals.
I don't think we can sustain that.
You see the dog pounce on the ball, drop it at your feet and stand
looking at you wagging its tail. Even I
have some difficulty denying that there is some intention there, although I may
wish to be slightly more circumspect than some dog-lovers about the precision
with which the dog is expressing that intent.
But get out a piece of meat and the dog forgets the ball immediately. It is a trivial example, but it is
informative about the understanding of language. The dog clearly has intentions and can, in a sense, judge between
them - or can it?
It is
often suggested that there can be "proto-language" or that there can
be more or less complex languages and that there is a continuum between the
vocalisations of primates and language.
It is vain to deny that , in an evolutionary process, there are breaks
so sharp that a continuum cannot be seen.
nevertheless, we contend that there is a step in the evolution of
communication systems that is so sharp that it could be seen as
fundamental. This is the notion of
displaced reference, referred to at the conference by Kendon.
Language,
by any definition, is a system of symbolic communication capable of referring
to things in the absence of those referents.
There is no necessary relationship between the symbol (word) and the
referent - this is the notion of arbitrariness. But there is a convention about the relationship between sign and
signified, so that a community of language users all understand the same thing
(or nearly the same thing) by the sign.
This arbitrariness defined by convention allows the possibility, and is
allowed by the possibility of meaning.
I suggest that it is in the process of infant development that children
acquire this sense of meaning, and it is the growth of meaning that joins the
comprehension of language to the production of language, and which makes the
comprehension of cognition possible. In
the distinction made by Ingold, after Ryle, "knowing how" is
transformed into "knowing that".
This is such a fundamental difference between human communication and
the communication systems of all other animals that I think it is useful to
consider it as a sharp break along the continuum - a high step, such that once
it was surmounted people could see further in the real world, and create
imaginary worlds and share them with others.
They could engage in what Parker, at the conference, called declarative
planning.
There is
general agreement that this transformation had occured by the time of the Upper
Palaeolithic of Europe. Noble and I
(Noble & Davidson 1989) have suggested that the imagination required to
build a boat to get to the unknown shores of Australia before 40 thousand years
ago required such knowledge. The
question is how much earlier it can be seen.
And this is the interest of handaxes.
Handaxes
are the most obviously designed product of the lower Palaeolithic. Did that their production necessarily
involve design, knowing the form of the end product? John Gowlett has argued that it did, I would like to suggest
otherwise. Consider, for a moment, the
proposition. A handaxe takes about 40
minutes to make, depending on the prettiness desired, the skill of the knappper
and the nature of the raw material. The
proposition is that hominids invested this sort of time in making a tool for
future use. If you could demonstrate
that sort of delay (or displacement in time) between conception of need and the
possibility of satisfying it, then hominids would be far more competent that I
take them to be. To adjust an
Australian expression, that is far more outstanding than dogs' balls.
So how do
I account for handaxes? Was there an
intention to produce the stereotyped shape so familiar to us all? Well, the first question I have is how
stereotyped are they? Or rather, in a
complete Acheulean assemblage (and how do you measure completeness?), how much
can we say that the only intended product was a handaxe? Or do archaeologists selectively define
handaxes by shape or technology of production such that the stereotypy derives
from the classification process? Most
fundamentally, were the flakes used?
There are some indications from Potts' recent excavations at Olorgesaile
that they were. And if flakes were
used, can the production of bifaces be simplified into decisions made in the
context of producing flakes, which reduces the time depth of the
intentionality? I find that these
questions are rarely being asked, but they hold the key to understanding
hominid evolution. If hominids had 40
minute depth to their intentionality, I cannot imagine that they did not have
language. But if they had language, I
cannot imagine that they did not create more than they did. It seems strange that there should be no
products other than tools that could be considered to have symbolic content,
defined by arbitrariness and convention, earlier than the Upper Palaeolithic
and the colonisation of Australia.
There is the paradox.
CONCLUSIONS
I began by
discussing Kanzi and infant development and have ended with handaxes. How are these related, except by being
topics at the conference?
There is
general agreement that by the time of the colonisation of Australia there was
displaced reference, hence language.
Yet there seems to be a problem that the earliest appearance of
anatomically modern Homo sapiens is accompanied by Mousterian industries, as
are the latest archaic Homo sapiens - and in these industries too we might
explain the variability by imitative learning, restricted patterns of motor
action, and modification through or for use.
All these features we might associate with hominids lacking the
creativity of language-using humans. In
the back of the mind (another of those danger words) of many people is an
anxiety because their expectation is that once the skeletal morphology looks
like us then they should be behaving like us.
It is a hangover, I think, from the erroneous subliminal belief that
natural selection creates variability.
Certainly Lieberman seemed worried by the expectation. I believe that this has always been unlikely
- what we have to account for is why one end of the range of variation of a
polymorphic species should have become more successful than another. And here, I think, Lieberman and Kanzi hold
the key.
Lieberman
long ago demonstrated that there were differences in the ability of different
morphologies to vocalise, whether or not you accept all of his claims about
this. Kanzi's language comprehension
and novel vocalisations demonstrate that performances that are not part of the
normal repertoire of a species may be stimulated by a favourable developmental
environment. What has evolved, in fact,
is development. Once displaced reference
and symbols in communication were invented, and could become part of the developmental
environment of hominids, syntax and semantics could expand.
The
evidence from gestures of deaf children of hearing parents, from the
gesticulations that accompany speech in normal humans, and from the invention
of gestures by chimpanzees in tool use, suggests that Gordon Hewes was close to
the answer - more complex communication arose through gesture. As Sue Savage-Rumbaugh suggested, such
gestures "coalesce on tools" and thus may "carry things through
time". But this will not achieve
displacement. That requires that the
gestures somehow become dissociated from the context and contingency of use -
and that is the scenario that Noble and I produced in our Current Anthropology
paper.