been an important aspect of their way of life and provided a platform for the elaboration of culture that we can first discern in the lithic artifacts of Oldowan and Acheulean tool makers (Goren-Inbar 2011; Stout 2011).

Additionally, Whiten et al. (2009b) noted that the collated wild chimpanzee data indicate that there is a drop-off of 50 % in shared cultural traits over distances of around 700 km. Applying this scenario to Oldowan sites leads to such expectations as that for the example of Koobi Fora, as many as seven other sites, from Fejej at 49 km to Melka Kunture at 489 km, would be expected to share around half their cultural traits, with more distant sites sharing less. It is hoped that such models may stimulate more systematic comparisons of potential cultural patterning in the relevant lithic assemblages.

Cultural Content: Percussive Technology

The cultural repertoires of closely related species may also share similarities in their particular behavioral content. One graphic example of this is that large numbers of related species of passerine birds share the culturally-transmitted content that is birdsong – quite unlike other taxa such as primates, where vocal learning is minimal at best.

Perhaps of most interest to readers of the present, archaeologically-focused volume is that one of the major cultural content similarities between chimpanzees and ourselves lies in tool use, including percussive and other ‘power’ tool use (Whiten 2015). Chimpanzees fashion and use a greater diversity of tools (or forms of material technology, in the broadest sense) than any other non-human animal (McGrew 1992; Whiten 2011). Some are used for cleaning the body, such as leaves and other vegetation used to wipe off blood, feces or semen, or stems to probe the nostrils; some are used for comfort, such as leaf mats on wet ground; and some are used in courtship, like leaf-clipping with the teeth to make a distinctive sound. Use of hammer stones or pieces of wood to crack a variety of kinds of nut are therefore just one among a variety of other forms of tool use that represent local traditions. Nut-cracking is of particular significance in relation to the origins of stone tool manufacture, the first signs of which date to about 2.6 Ma in the fossil record. This is because the content of both stone tool making and nut-cracking using a stone hammer involve a suite of shared features: typically the body is truncally erect, and the agent is sitting; they then bring a rock down on another object they are holding or have placed on an anvil object in a precisely controlled and targeted fashion, because it is vital for success to strike either the nut (in nut-cracking) or the other stone (in knapping) at just the right place and angle and with controlled force. This necessarily requires a good appreciation of the use and control of such targeted

force. If our ape ancestors used percussive tools for nut-cracking in this way, this would have provided an important preadaptation for stone tool knapping.

Nut-cracking, however, is not an isolated oddity in the chimpanzee repertoire but instead is part of a family of other percussive forms of tool use. These include clubbing, pounding (in a variety of contexts, from breaking into bees’ nests, to the mashing of palm growing points that is ‘pestle pounding’) and stabbing into tree holes that might contain prey like bushbabies. These percussive variants are in turn elements in a broader family of ‘power’ tool usages that include levering and forceful puncturing (e.g., of the ground, to form tunnels down to subterranean termite nests, then exploited using long fresh stems as fishing tools). This variety in power-dependent tool use, which is described in more detail by Whiten et al. (2009b), entails a quite elaborate appreciation of the effective use of force, including controlled levels of power and the implications of different striking or levering angles. Again, the sharing of such characteristics between chimpanzees and humans suggests they are derived from a common ancestor. The emergence of the earliest stone knapping thus did not have to emerge out of the blue, but instead would have been able to exploit a matrix of relevant and useful psychological attributes concerned with power-dependent tool use.

Social Learning Processes

Earlier in this chapter, I noted that social learning of some kind is widespread in the animal kingdom. However, there are many different kinds and grades of social learning, which vary in their psychological complexity and in the information that gets transmitted from model to learner (Whiten et al. 2004). Stimulus enhancement, in which what a model does merely channels or focuses a social learner’s attention, appears to account for much of the social learning that is increasingly recorded as ubiquitous in animals. Through this relatively simple process, animals can learn such things as what items to eat and where to find them, and this can sustain traditions that operate at this level of information.

When it comes to learning how to do things, however, more sophisticated forms of social learning are required. Learning by observation how to use a stone to crack a nut, or to shape another stone, for example, requires some kind of copying process. One well-known mechanism to achieve this is imitation, defined by Whiten and Ham (1992) as copying the form of an action. However, students of social learning have distinguished another process, emulation, that can also involve copying, but with a focus on the environmental results of actions rather than the actions per se. Consider as an example, a diffusion experiment in which one

capuchin monkey in each of two groups was taught to open an artificial fruit, but using a different technique: one learned to grasp a knob on a flap-door and lifted the door, whereas the other learned to grasp the same knob but slid the door and its frame to one side. After these initial models were reintroduced to their groups, the two methods spread differentially, forming incipient ‘lift’ and ‘slide’ traditions in their respective groups (Dindo et al. 2009). Because both models grasped the handle on the door, stimulus enhancement could not explain the difference in what their companions learned: instead, learning by imitation or emulation was implied. In this example, imitation would involve copying the different actions involved in lifting versus sliding, whereas emulation would involve recreating the lifting or sliding action of the door, however achieved. Further experiments would be necessary to distinguish these, and relatively few of such studies exist as yet.

Much evidence converges on the conclusion that whatever copying occurs in non-human primates, it is typically of low fidelity by human standards, even in chimpanzees (Whiten 2011). This has suggested to some that what is happening is in fact only emulation, rather than imitation, and that this is what explains the paucity of evidence for cumulative culture in all but our own species, because cumulation requires good fidelity copying of each level of achievement attained, before the next innovation ratchets the behavior up a notch.

However Whiten et al. (2003) were skeptical of this conclusion. One reason is that in chimpanzees, the quality of copying has been demonstrated to be of sufficient fidelity to maintain group differences in action patterns that are quite complex. This has been particularly apparent in suites of

recent diffusion experiments in which some multiple-action sequences have not only spread within groups, but have been transmitted to neighboring groups (Whiten et al. 2007). Moreover, there is evidence of imitation, as well as emulation, being used selectively, with switching between these approaches to social learning according to the learning context (Horner and Whiten 2005). In ‘do-as-I-do’ ‘Simon-says’ games of arbitrary copying that chimpanzees and orangutans (unlike monkeys) can be trained to play, both ape genera have demonstrated they are capable of bodily imitation, and there is evidence, too, of imitation of the sequential structure of more complex actions by chimpanzees (reviewed more fully in Whiten et al. 2009; Whiten 2011). Finally, in a study in which naive young East African chimpanzees (who do not crack nuts in the wild) were shown to learn nut-cracking from a skilled older individual, they were observed on occasion to mimic the ongoing nut-cracking blows of the model they were watching alongside them (Marshall-Pescini et al. 2008a; see Fig. 4.3). The fact that they had no stone in their hands and no nut in front of them means it is difficult to see this as any form of emulation, but rather as a form of imitation in which there is a bodily identification with the other individual of the kind one might expect from the operation of mirror neurons (Hopper et al. 2012; Whiten 2013b; Furhmann et al. 2014), that have been associated with imitation in humans (Iacoboni 2012). Thus, while our comparative research leads us to concur with Tennie et al. (2009; and see Tennie et al. 2016) that human imitation can be of significantly higher fidelity than in chimpanzees, the above array of evidence suggests that chimpanzees have sufficient copying ability to sustain different traditions (including tool-based ones) and draw on imitative as well as emulative processes.

Fig. 4.3 Novice juvenile chimpanzee observing proficient older individual using a stone hammer to crack nuts. Drawing from frame of video showing observing chimpanzee to imitatively match actions of

the expert model (after Marshall-Pescini and Whiten 2008a: video viewable in electronic supplementary information at: http://dx.doi.org/ 10.1037/0735-7036.122.2.186.supp). Drawing by Jason Zampol

Imitation, Emulation, and the Cultures

of the Oldowan and Acheulean

The debate about the imitative and emulative capacities of apes and their implications for the occurrence of cumulative culture bear rather directly on the nature of culture as it came to be expressed in the Oldowan and Acheulean phases of hominin cultural evolution. The transition from the Oldowan to the Acheulean itself appears as one of the first manifestations of cumulative culture in the hominin archaeological record, with the latter phase (Goren-Inbar 2011; and see Alperson-Afil and Goren-Inbar 2016) building on the cruder achievements of the earlier one (Stout 2011). Stout (2011) argues that subtle signs of cumulative progress are already discernible within the Oldowan.

One explanation for what made these cultural evolutionary steps possible is that early humans developed special new social learning capacities, in particular, imitative as opposed to emulative ones (Tomasello 1999). By contrast, our own research demonstrating chimpanzees’ capacities to sustain material traditions, coupled with evidence of a degree of imitative fidelity, suggests that similar social learning powers would already have existed in the forebears of early hominin social tool makers, such that a step up in social learning would likely not be the key explanation for the emergence of cumulative lithic culture. Whiten et al. (2003), in first developing this argument, were led to propose that the psychological advances may have lain instead in those more directly underlying the cognitive requisites intrinsic to technological innovations such as those of the knapping process. As neural and cognitive advances were made in this respect, the imitative capacities were likely in place to assimilate the technological innovations of the most gifted hominin tool makers.

Some support for this argument comes from within archaeology itself, deriving from the fact that although one can discern cumulative progress in the Oldowan and Acheulean phases, it was inordinately slow. Indeed, over some periods of hundreds of thousands of years (and thus, many thousands of generations) the principal picture is one of stability of cultural inheritance, even across much of the Acheulean (Goren-Inbar 2011). However, as Mithen (1999) was perhaps the first to suggest, the transmission of skills as sophisticated as knapping Acheulean blades must have drawn on imitative capacities. Accordingly, in this phase of hominin evolution one has imitation, yet barely discernible cumulative cultural progress: so the emergence of imitation was not the magic factor responsible for the emergence of cumulative culture. Advances in the non-social cognitive requisites of biface knapping may have been more crucial in the emergence of the Acheulean lithic achievements, as well as the more elaborate forms of lithic cumulative culture that followed (Whiten et al. 2003; Faisal et al. 2010).

The Evolution of Human Culture, Deep

Social Mind and the Socio-Cognitive

Niche

In this final section I address the broader cognitive and ecological contexts of the evolution of human culture, referring to an analysis recently published at much greater length, that readers are encouraged to consult for more depth and detail (Whiten and Erdal 2012).

The starting point is essentially the puzzle of how our puny ape ancestors evolved into a hunting-gathering niche that extended to the hunting of large game, in direct competition with a large guild of formidable African predators including the big cats. How was this possible? An influential answer was expounded by Tooby and DeVore (1987), who proposed that evolving humans triumphed in this competition by creating a ‘cognitive niche’ that gave its exponents a significantly superior edge in hunting through the applications of greater intelligence.

Archaeology provides historical evidence of ancient origins to such hunting of big game, including sophisticated spears from 300 ka (Thieme 1997) as well as cut marks on large bones from much earlier times. Building on this framework, studies of peoples who have, until recently, pursued a hunting and gathering way of life (and in some cases continue to do so), have become important sources of inference about human ways of life before the very recent (*10 ka) origins of agriculture. These and other studies led Whiten (1999, 2006; Whiten and Erdal 2012) to suggest that the ‘cognitive niche’ concept, whilst eminently plausible as far as it goes, needs to be extended to the broader concept of a ‘socio-cognitive niche’, underwritten by a complex of cognitive features that together can be characterized as a uniquely human ‘deep social mind’. Deep social mind refers specifically to a complex of cognitive processes, while the socio-cognitive niche (like all ‘niche’ concepts) refers to the ways in which the organism engages with a subset of environmental features.

Whiten and Erdal distinguish five main pillars that characterize both concepts. Human cumulative culture represents just one of these pillars. The others are language, theory of mind (aka mindreading or mentalism), egalitarianism and unprecedented levels and forms of cooperation (Fig. 4.4). The significance of this picture is that the nature of human culture must be understood as part of this larger set of socio-cognitive adaptations, between which numerous positive feedback loops can be inferred (Fig. 4.4). The crucial outcome of the operation of this complex is that a hunter-gatherer band functions in the manner of an extremely efficient group-level predator, beyond anything seen in competing social carnivores. Key features that distinguish it from the latter include organized division of labor, planned

Fig. 4.4 Principal classes of social cognition (in bold capitals) in hunter-gatherer bands and, inferred reinforcing relationships between them (after Whiten and Erdal 2012). Note that the latter cannot be

exhaustively illustrated in a legible single figure; those shown are indicative only. For explanation and discussion see text

cooperation and a material culture that has cumulatively created sophisticated weaponry.

To flesh these ideas out a little more (see Whiten and Erdal 2012 for a much extended treatment) consider Fig. 4.4. Cumulative culture and language are shown separately here, because instances of each exist independently of the other: for example, observational learning can contribute to culture without recourse to language; and language fulfills many functions daily, such as joint planning of forthcoming activities, other than specifically cultural ones. However, the two are bonded by positive feedback loops that include the use of language to transmit culture, and conversely the role of culture in the fundamental process of language acquisition. Other authors have recently sought in independent but complementary papers to extend the concept of the cognitive niche, particularly concerning culture (Boyd et al. 2011) and language (Pinker 2010) respectively; see also Sterelny (2012).

In turn mindreading – the attribution to others (and oneself) of states of mind such as ignorance and belief – has reciprocal links with both culture and language. For example on the one hand, mindreading supports explicit teaching through the correct attribution of states of knowledge and ignorance in the pupil; and conversely, one’s culture provides an explicit ‘folk psychology’ that specifies such mental states as true and false beliefs. Egalitarianism refers to the apparently universal occurrence in hunter-gatherer bands of egalitarian behavior reflected in a range of functional contexts that include resource-sharing according to need, and a lack of explicit leadership roles (Erdal and Whiten 1996). This

appears highly reciprocal, with extensive cooperation such as in foraging parties, because egalitarianism makes it functional to work together to gain the resources later shared. The links with culture include the ways in which egalitarianism is embodied in public ideologies that are transmitted from generation to generation, and the importance of content such as collaborative hunting and gathering technologies in supporting the importance of cumulative cultural capacities.

Figure 4.4 might be thought to be complicated enough, but it is important to recognize that its purpose is to outline principal pillars of the socio-cognitive niche in particular. In reality, this expansion of the concept of the cognitive niche must encompass much else that is cognitive, including the features discussed by Tooby and DeVore (1987). This should in principle expand Fig. 4.4 to show such features as tool making, and further multiple linkages of such features with those already in the diagram, but the figure would then rapidly become unwieldy. Ranging yet more widely to consider the features that make up the human adaptive complex as a whole, requires incorporation of such major changes to great ape patterns as significantly extended immaturity (long childhood and extended dependence on parental resourcing), bi-parental investment, massive encephalization, and perhaps neoteny. All of these characters, together with those outlined in Fig. 4.4, constitute an important matrix shaping and being shaped by the nature of culture in our species.

However, the five core characteristics highlighted did not spring out of the blue. All of them represent elaborations on