The Origins of Human Behaviour

Robert Foley

• Publisher: Routledge
• Year: 2003
• Topic: Social Sciences
• eBook ISBN:
  9781134998654
• Subtopic: Archaeology
• Index: Social Sciences

This volume explores the diverse ways in which the evolution of human behaviour can be investigated, and confronts the most challenging aspects of the subject.

1 Chimpanzee material culture: what are its limits and why?

W.C.McGREW

Introduction

It is a truism to say that behaviour and ideas do not fossilize. Hence, reconstruction of the origins of culture depends on artefacts and other remnants, the use and meaning of which are then inferred. Such inference may seem simple in principle but it is difficult in practice, for several reasons: first, cultural objects are not always distinguishable from natural ones; second, only a subset of enduring objects remains while perishable ones have been lost; and third, deposition and sometimes recovery is nonrandom, and so what remains in the archaeological record is biased. The upshot of this can be summed up in two aphorisms: ‘Absence of evidence is not evidence of absence’ and ‘Presence proves only possibility, not probability’. In the case of the former, one could not infer that early hominids did not use digging sticks, as these tools would inevitably be lost to us. In the case of the latter, concentrations of fragments of fired clay need not imply human agency, as natural sources may be equally likely.

These difficulties may be eased by looking for the closest living approximation to the extinct hominoid forerunner. Such referential models (Tooby & DeVore 1987) will not be identical, obviously, but the closer the fit, the better. The big advantage thus gained is that directly observable behavioural data will be available to supplement the artefacts. At the very least, this shows the minimal capacity of an early hominid. It is necessary, but not sufficient, evidence.

Consider an idealized example. An ape is seen to make and use a stone tool which is indistinguishable from a similar object thought to have been made by an early hominid. This may mean nothing more than limited but certain knowledge of one way in which that artefact could have come about. However, it is a tremendous advance, because one now has available for study the behaviour and mind of the user. For an empiricist, this is worth all the speculation, however fascinating, in the world.

So, how to choose the best model? Even a glance at the palaeoanthropological literature shows no consensus. Some models rely solely on living human beings and exclude other species. Such approaches rightly favour tropical, open-country-living, hunting-and-gathering people, especially in Africa (Musonda, Ch. 3, this volume). Other models follow either homology, and make use of nonhuman primates, or analogy, and make use of social carnivores. My aim here is to focus on the common chimpanzee, Pan troglodytes, in both ways.

The chimpanzee is apt for several reasons. It is well studied, both in the wild and in captivity. Anatomically and genetically, it is our closest living evolutionary relation. Most important, it is a culture-bearing creature in its own right. (This last point is debatable and may be a curse as well as a blessing; see Foley, Ch. 2 this volume, McGrew 1990.)

Of course, as others have used the chimpanzee model before, the reader might well ask that more can usefully be said. The answer is that if the most complete and thoughtful earlier work was done by Tanner (1981, 1987, 1988), then new findings have already rendered it out of date. The new knowledge comes from several sources. In captivity, unprecendentedly rich and creative experiments and observations have been done with chimpanzees. In nature, several new field sites and studies have been developed, as well as older ones expanded. In palaeoanthropology, new techniques for analysis of artefacts and fossils yield data never before available and, in some cases, not even imagined. Archaeological evidence is much improved in quality as well as in quantity, especially in terms of careful, systematic collection. Perhaps most important, analysis is tighter and more rigorous, relying on explicit, step-by-step argument and stated, falsifiable hypotheses, rather than seductive but slippery scenarios. Thus my aim, restated, is to answer the following question: given recent knowledge, is the chimpanzee a better or worse model for human evolution than before? In tackling this problem, the catchier question posed in this chapter's title should be dealt with too.

A cautionary note: culture is not a concrete entity but a mental construct. It is a set of concepts and as such cannot truly evolve. However, capacities for culture can evolve in organisms, and manifestations of culture, such as artefacts, can evolve in the sense of showing changes in design, features, etc. Being tangible, material culture is the easiest point at which to start retrospective analysis, but it is not enough to stop at the material. To be used meaningfully, the term culture implies associated symbol-use by the culture-bearer. Thus reconstructing cultural evolution may start with objects for convenience, but must carry on to assess the symbolic significance that is implicit in the artefacts.

On another front, there is disagreement about the various extinct forms for which the chimpanzee has been proposed as a model. At least four have been put forward in print: first, a Miocene stem-form of ancestral ape; second, a Mio-Pliocene ancestral hominoid, which cannot be assigned confidently to either Pongidae or Hominidae; third, the first recognizable Pliocene hominid; and fourth, a later, Plio-Pleistocene hominid, the first indisputable member of the genus Homo (McGrew 1989). The first of these may correspond to Proconsal; the second is unknown; the third, an australopithecine or H. habilis; the last, H. erectus.

For reasons elaborated upon elsewhere (McGrew, 1990), it seems likely that only the middle two need be taken seriously. The first is too conservative, in that it was probably a precultural form, more like a present-day gibbon. The last is too advanced, in that living chimpanzees arguably show neither the cultural nor the bodily similarities needed to draw direct comparisons with large-brained Homo. Of the middle two, the ancestral hominoid is to be preferred on grounds of caution, but it must be an underestimate if the living chimpanzee is a culture-bearer (unless one assumes cultural devolution). It is hardly likely that pongid culture has stood still over the last 6 million years. On the other hand, if the living chimpanzee most resembles an australopithecine, then we must be faced with cultural convergence, or parallelism, since phylogenetically the pongid and hominid lines had already diverged, or, to be more precise, at least one radiation had occurred.

Culture and symbols

As might be expected, culture is as hard for anthropologists to define operationally (as opposed to theoretically) as intelligence is for psychologists or language for linguists. It is not enough to say that culture includes all things human, for a concept that explains everything explains nothing; it is not heuristic. Thus a working definition is crucial if one is to tackle the evolutionary transition from a precultural to a cultural state. If the change had intermediate, protocultural states, then precision and explicitness are all the more important. For the sake of this chapter, culture will be thought of as being made up of observable actions and inferrable thoughts. The former has been covered in an earlier work, using a set of eight criteria: innovation, dissemination, standardization, durability, diffusion, tradition, nonsubsistence, and natural adaptiveness (McGrew & Tutin 1978). Chimpanzees show all of these, but it is the last which needs attention here.

Cultural organisms must have the mental abilities to create and use symbols; otherwise, one would have pseudoculture, which is essentially mindless, social learning. In other words, self-aware symbol-use is a necessary prerequisite of culture. (Contrary to what is sometimes said—for example, by Washburn and Benedict (1979)—it is symbol-use and not language which is critical. The two are not synonymous, as language is only a subset of symbol-use. This is clear from studies of nonverbal humans such as autistic children.) So, do chimpanzees show self-awareness and use symbols?

The answer on both points seems to be yes. Gallup's (1970) elegant experiment on chimpanzees recognizing themselves in a mirror has been much repeated and elaborated upon. Woodruff and Premack (1979) have shown that chimpanzees seek to deceive humans both by omission and by commission. Savage-Rumbaugh et al.'s (1978, 1980) series of careful studies has shown chimpanzees using simple symbols to label, sort, and ask for objects such as food or tools. They do so among themselves, in the absence of humans. All of these demonstrations come from laboratories and so remain to be confirmed in nature, but the capacities are clearly present and are used in social life (de Waal 1982).

Environment and adaptation

Despite evidence to the contrary, prehistorians continue to think dichotomously about the correlation between environment and hominoids. Living chimpanzees and their pongid ancestors are classed as forest-dwellers, while hominization is linked with adaptation to the savanna. Given this neat division, chimpanzees would seem to be precluded as evolutionary models for any hominid on basic ecological grounds. In fact, recent findings show that neither distinction holds. While the picture of an African Plio-Pleistocene vegetational mosaic of scrub, deciduous open woodland, grassland, and scant gallery forest remains typical, this was punctuated by periods of expansion of humid rainforest (Williamson 1985).

More to the point, wild chimpanzees live in hot, dry, and open environments today, both in East and West Africa. Long-term studies have been carried out at Mount Assirik, Senegal, where less than 3 per cent of the surface area is forested (McGrew et al. 1981). Climatologically, hydrologically, floristically, and faunistically, this is a savanna. At the least, the studies show that chimpanzees as a species are much more adaptable than usually credited, and so must be eligible as possible models for either forest-living ancestral hominoids or savanna-living hominids.

More pertinent to the origins of culture is the extent to which the chimpanzee toolkit (and hence by analogy the ancestral form's material culture) varies with environment. While some aspects of chimpanzee material life such as nest-building are largely constant (see p. 19), variation in other aspects occurs across populations. Tools used to obtain termites for food differ over three widespread sites (McGrew et al. 1979). Moreover, such variation also occurs between communities in the same population (McGrew & Collins 1985). In both cases, some differences reflect contrasting features of habitat (for example, availability of prey), while others appear to reflect contrasting social customs (for example, preferences for raw materials). Finally, pan-African comparison of techniques by which a specific food item, the oil palm nut (Elaeis guineensis), is processed and eaten by chimpanzees, shows a range of cultural complexity (McGrew 1985). Some populations ignore the nuts, others eat only the outer energy-rich husk, and other also use stone tools to extract the protein-rich kernel.

All of this sounds familiar when one recalls early hominid cultural traditions described on the basis of different lithic industries (Leakey 1975). Recent reassessments (Toth 1985b) are more cautious in their interpretations and inferences and are even closer to the chimpanzee model. For example, early hominids at Koobi Fora may not have depended on stone tools and may have used them only in certain habitats. In some cases, prehistorians and primatologists working independently, with different data, have come to very similar conclusions: for example, that design of tools is demonstrably a function of the size, shape, and mechanical properties of the raw materials (Jones 1981, McBeath & McGrew 1982, Boesch & Boesch 1983).

In summary, recent ecological studies of wild chimpanzees and their material culture strengthen rather than weaken the case for their being used as models of human cultural evolution. Also, they underline the importance of environmental variables as influences on culture. However, they do not yet allow palaeoanthropologists to match the chimpanzee model with a particular ancestral form.

Diet

Overall, diets of wild chimpanzees and ancestral hominoids and hominids look more and more similar. Both are omnivores, or, more exactly, mainly frugivores with a taste for opportunistic faunivory.

All closely studied populations of chimpanzees are known to eat animal as well as plant matter. Short- and long-term studies of both tamed and untamed wild apes in a variety of habitats show them to eat social insects and small-sized mammals such as monkeys and young ungulates (Teleki 1973, McGrew 1983, Takahata et al. 1983, Boesch & Boesch 1989). Also, cannibalism, once considered aberrant, is now recognized and explicable (Goodall 1977, Nishida & Kawanaka 1985). Thus, meat-eating is species-typical.

However, there are dietary differences between ape populations in the species of prey chosen, and these seem to be understandable only in terms of cultural differences (McGrew 1983). Techniques for getting meat vary too. Chimpanzees stalk as well as stumble upon prey, and after seizing the victim may kill it in several ways (Teleki 1973, Boesch & Boesch 1989). Sometimes extractive foraging of hidden prey occurs: f...

Table of contents

• Front Cover
• Half Title
• TITLES OF RELATED INTEREST
• Title Page
• Copyright
• Contents
• List of contributors
• Foreword
• Preface
• Introduction: investigating the origins of human behaviour
• 1 Chimpanzee material culture: what are its limits and why?
• 2 How useful is the culture concept in early hominid studies?
• 3 The significance of modern hunter-gatherers in the study of early hominid behaviour
• 4 Archaeological evidence for modern intelligence
• 5 The invention of computationally plausible knowledge systems in the Upper Palaeolithic
• 6 An interactive growth model applied to the expansion of Upper Palaeolithic populations
• 7 Aboriginal fossil hominids: evolution and migrations
• Index