THE ACHEULEAN HANDAXE – A CASE OF TECHNOLOGICAL PERSISTENCE?

The handaxe is recognised as the hallmark of the Acheulean cultural complex for three main reasons: its wide geographic distribution; its continuous presence throughout the Acheulean (1.8/1.6–0.25 Mya in Africa and the Levant); and its persistent morphology and production technology. These characteristics have earned the handaxe the sobriquet ‘the Swiss Army knife of the Palaeolithic’. Various views concerning the level of technological stagnation or of change are often derived from the research terminology: stasis, stagnation, conservatism, slow change, monotony, and so forth. Each of these terms has its distinct nuance and thus represents a different level of ‘freedom’ in interpretation. While this article focuses on the continued persistence of the handaxe in the Acheulean cultural complex, some noticeable lithic innovations, such as prepared core technologies (eg, Adler et al. Reference Adler, Wilkinson, Blockley, Mark, Pinhasi, Schmidt-Magee and Nahapetyan2014; Nowell & White Reference Nowell and White2010) and the production of small flakes by means of recycling (eg, Agam et al. Reference Agam, Marder and Barkai2015; Shimelmitz Reference Shimelmitz2015) also took place alongside the tool’s apparent stagnation. These innovations, however, were not as geographically and chronologically widespread as the persistence of the handaxe. The following views relate to handaxe persistence and its bearing on Acheulean technology and culture.

The differing views on the issue can be divided into two schools: those that perceive stasis and those that emphasise a slow change. The terminology used to define the Acheulean technology by members of the first group include: ‘conservative’ (Scarre Reference Scarre2009, 95); ‘behavioral conservatism’ (Klein Reference Klein1999, 337); ‘essentially unchanged’ (Gamble Reference Gamble2007, 221); ‘rigid conformity’ and ‘conservatism’ (Bar-Yosef Reference Bar Yosef2006, 483); ‘essential ideas were handed over from tool-maker to tool-maker over an exceptionally long period’ (Lycett & Gowlett Reference Lycett and Gowlett2008, 309). Pope et al. (Reference Pope, Russel and Watson2006, 54–5) reached a similar conclusion regarding the symmetry and aesthetic form of the handaxe. Other scholars present data from specific sites, employing similar terminology such as: ‘definite conservatism’ (Gesher Benot Ya’akov, Israel: Sharon et al. Reference Sharon, Alperson-Afil and Goren-Inbar2011, 395); ‘remarkably strong intra-assemblage uniformity … strong rules or conventions in technological operations’ (Awash region, Ethiopia: Schick & Clark Reference Schick and Clark2003, 26); ‘uniformity … is consistent with a pattern of strong conventions held across Acheulean society’ (Hunsgi and Baichbal Valleys and Isampur Quarry, India: Petraglia et al. Reference Petraglia, Shipton and Paddayya2005, 208).

The second school of thought, which acknowledges the existence of variability, includes Nowell and White, who contend that although the convention concerning the ‘… technological conservatism of unparalleled magnitude, a million years of stasis usually attributed to the limited cognitive and linguistic abilities of the hominins involved’ (2010, 70), this misidentified stagnation is the result of analytical shortcomings. These researchers contend that handaxe variation can be detected at the global, regional (eg, in UK – see also a recent study by Bridgland and White (Reference Bridgland and White2015) suggesting chorological changes reflected in biface assemblages) and site levels (such as Boxgrove). They also state that the innovation and adoption of the handaxe itself was substantial (and flexible) enough to support transformations in the life history of Acheulean hominins. Inventiveness is suggested to have produced variations on a theme in the Acheulean, as in the case of the ‘prepared cores’ at Gesher Benot Ya’akov, Cagny La Garenne, France, and other sites, but these were relatively local (Nowell & White Reference Nowell and White2010, 73). It is generally assumed that a threshold – demographic, cognitive, physiological, social, or a combination thereof – had to be passed in order to make the next local ‘invention’ a global innovation (see also Hopkinson et al. Reference Hopkinson, Nowell and White2013).

Hosfield (Reference Hosfield2008, 15) suggests that the gap between the ‘sheer longevity and overall morphological stability of the Acheulean handaxe’ and behavioural variability and flexibility found in other aspects of hominin life is due to differences in research resolution. He suggests that the morphological stability of handaxes is not a reflection of behavioural stability, but is due to problems with the identification of handaxe variability. Other researchers who seek to explain the Acheulean industry variance still begin from the assumption of stasis (Machin Reference Machin2009, 36). Based on the same assumption, Hopkinson and White (Reference Hopkinson and White2005, 23–5) engage with the role of the individual in creating the variance/stagnation in the Acheulean handaxe industry. Somel et al. (Reference Somel, Liu and Khaitobich2013, 113) present an account of human brain evolution and employ the phrase ‘limited progress’ to describe the Acheulean technology.

McNabb et al. (Reference McNabb, Binyon and Hazelwood2004) argue that the reason for diversity among handaxes should be attributed to the stylistic choices of the individuals who made them. McNabb and Cole (Reference McNabb and Cole2015) recently employed orders of intentionality as a measure of cognitive evolution in order to suggest that what we observe today is basically variability, appearing within long periods of apparent stasis.

In conclusion, some perceive the Acheulean technological stagnation to be represented by a single tool type – the handaxe – that consistently appears both chronologically and geographically. Within this ‘stagnation’, variations exist in its manufacture and use at different sites and in different periods. For our case, including all its variations, the handaxe was sustained as the same ‘tool category’ (similar, in a way, to the modern hammer, axe, knife, or chopstick, which retain the same basic shape and function, albeit with many variations) for a prolonged time span, and we refer here to this continuity as ‘stagnation’.

TRANSFORMATION IN OTHER AREAS OF HUMAN BEHAVIOUR

Unlike the suggested ‘stagnation’ in handaxe technology, the Acheulean cultural complex features a variety of transformations in other fields. Before presenting some of these in brief, it is worth noting that at least two different human groups were producing and using handaxes: Homo ergaster/erectus and Homo heidelbergensis, and that Neanderthals continued to make bifaces in late Middle Palaeolithic Europe (however, we should keep in mind that the jury is out regarding the variability within the genus Homo; see for instance Schwartz & Tattersall Reference Schwartz and Tattersall2015). Machin (Reference Machin2009) surveyed several changes in Hominin characteristics between 1.8 Mya and 500 Kya, such as the increase in body size, brain size, and encephalisation; the development of communication and social complexity; changes in life history (longer periods of childhood and adolescence); social organisation; and strategies for procuring raw materials and food provisioning. Regarding food, Machin emphasises the rising place of meat in the diet and the transition from scavenging to hunting; a suggestion that has been recently strongly reinforced (Domínguez-Rodrigo & Pickering Reference Domínguez-Rodrigo and Pickering2017). The need for lengthy parental supervision might have led to monogamy, the division of labour between man and woman, intra-group changes, and the promotion of social learning (Machin Reference Machin2009, 38–40; Nowell & White Reference Nowell and White2010, 74–6). Regarding human cognitive abilities as reflected in the findings at Gesher Benot Ya’akov, Goren-Inbar (Reference Goren-Inbar2011) argues that inventions undoubtedly occurred in the Lower Palaeolithic: eg, the use of the soft hammer for shaping handaxes and the early appearance of the Levallois method (or prepared core technologies) that flourished later in the Middle Palaeolithic. Regarding the dissonance between these developments and handaxe stagnation’, Goren-Inbar further contends that ‘These innovations, together with the creativity expressed in the full control of fire and its uses, clearly negate the notion of stagnation and/or stasis’ (2011, 1045).

Dennell (Reference Dennell2009, 335) emphasises the transition to big game hunting in the Lower Palaeolithic and Klein (Reference Klein1999, 343–60) reviews transformations in human behaviour during the Lower Palaeolithic and the changes in various areas such as the use of fire, non-lithic tools, and the types of animals hunted. Nowell and White (Reference Nowell and White2010) argue that significant changes in human life history occurred in the Middle Pleistocene, such as increased geographic dispersion, and meat eating. The migration from Africa to Asia and Europe required abilities that enabled adaptation to diverse environmental and climatic conditions. Finally, the basic question remains: How can we explain the gap between the range of biological, social, and technological transformations and the ‘stagnation’ in handaxe technology?

POSSIBLE CAUSES FOR ACHEULEAN HANDAXE TECHNOLOGICAL ‘STAGNATION’ & THE LACK OF INNOVATION

Scholars combine various fields of research (human cognition, knowledge and information transmission, social learning, and demographic variables such as group size, composition, and distribution) to explain the apparent technological ‘stagnation’ in question. We contend here that the fundamental flaw in these theories is that if they hold true for the handaxe, then they are assumed to hold true for other transformations as well.

Recently, Corbey et al. (Reference Corbey, Jagich, Vaesen and Collard2016) suggested that handaxe persistence in time and space is better explained not only by cultural and social reasons but partly by genetic inheritance. Moncel et al. (Reference Moncel, Arzarellob, Boëdac, Bonilauri, Chevrier, Gaillard, Forestier, Yinghua, Sémah and Zeitoun2016) somewhat follow this line of thinking, suggesting that the explanation for the combination of wide geographic distribution and the diversity of the handaxe lies in convergent evolution. In our view, such explanations need to be better supported and argued, and for the time being we therefore focus on functional–behavioural–cultural propositions. The persistence in handaxe shape and technology is, according to Mithen (Reference Mithen1996), the result of technological information transmission, mainly via imitation mechanisms. Given the complexities of handaxe manufacture, a more advanced learning mechanism known as ‘guided learning’ may have also been involved. Shipton and Neilsen (Reference Shipton and Nielsen2015) argue that the ‘unparalleled homogeneity of the Acheulean’ is due to over-imitation and shared intentionality. Recent studies have identified the presence of inexperienced knappers in specific ‘knowledge transmission grounds’ at Palaeolithic sites. These learning grounds may reflect the presence of knappers in the process of learning as well as learning transmission mechanisms at such sites (Assaf et al. Reference Assaf, Barkai and Gopher2015 and references within; Tehrani & Riede Reference Tehrani and Riede2008).

Lycett and Gowlett (Reference Lycett and Gowlett2008) contend that four models of cultural transmission can be taken into account: parent to offspring; teacher/leader to a number of individuals; numerous individuals to one individual; and peer learning. Each of these supports a different rate of innovation, dissemination, and consolidation. They further suggest that the low rate of innovation during the Lower Palaeolithic seems to be related to the parent-to-offspring model, although this method predicts inter-group variance that is not clearly observed in lithic findings of the period. A model of knowledge transmission from many individuals to one predicts a relatively low rate of innovation and greater variation between groups. Lycett and Gowlett (Reference Lycett and Gowlett2008) further suggest this model as suited to the Acheulean evidence. Stout (Reference Stout2011) argues that another factor in the innovation rate equation is that of the rise of technological complexity. As technological complexity increases, it creates the likelihood for more combinations to arise based on the existing variance, some of which will become the next innovations. He contends that sufficient complexity can be detected already in the Lower Palaeolithic, supporting the innovation of ‘pre-Levallois’ cores and knapping with a soft hammer to produce refined handaxes at 0.5 Mya (Stout Reference Stout2011). It should be noted that yet another mechanism for conveying information in social learning is that of conservatism transmission, which researchers of the Acheulean tend to ignore as a possible explanation for the handaxe paradox. Recent studies from the field of primatology also emphasise the explanatory potential of an approach focused on conservatism and functional fixedness (Gruber Reference Gruber2016; Wrangham et al. Reference Wrangham, Koops, Machanda, Worthington, Bernard, Brazeau and Muller2016). In the following we discuss the ‘conservatism transmission’ concept in greater detail.

Several approaches have been presented for reconstructing learning mechanisms in the Lower Palaeolithic. Their common theme is that relative technological stagnation is due to the low rate of innovation for reasons associated with learning ability and group size. None of the approaches suggests the possibility that the persistence could be due to a conscious and adaptive preference to produce the same tool type for generations.

Another view of preferred conservatism comes from studies of human life history. Nowell and White (Reference Nowell and White2010) argue that significant changes in human life history took place during the Middle Pleistocene. The rising place of meat and fat in the human diet is most likely related to the increased dependence on hunting, the adoption and use of fire, the reduction in gut size, the 20–60% expansion of brain size, and the increase in body size. All of these transformations are interrelated, though the sequence of cause and effect is far from being understood. The increased brain size led to the birth of helpless infants (relative to other mammals), which in turn led to extended infancy and longer puberty, as well as extended life expectancy long after menopause. To explain the relative technological ‘stagnation’, Nowell and White (Reference Nowell and White2010) distinguish between innovation – such as the adoption of the handaxe that marks the transition to the Acheulean – and inventiveness – a lesser degree of a novelty, such as variations in handaxe manufacture. How can we explain these processes according to the changes in human life history? Human life history is divided into five phases: infancy, childhood, juvenile, adolescence, and adulthood. Of these, childhood and adolescence are unique to the human species. Childhood has two important advantages: first, it allows the mother to stop breastfeeding and reduces the interval between births; and second – and of greater importance in our case – childhood allows 4 years of learning social behaviour. Adolescence provides the additional years of development that are essential for technological learning, experimentation, social integration, language acquisition, and other cultural transformations. The researchers suggest that Homo erectus childhood was shorter than that of Modern humans, which would have resulted in an imprinting of the handaxe ‘idea’ during the child’s early learning process from his ‘ultra conservative’ parents (Nowell & White Reference Nowell and White2010, 76). Nowell and White, however, do not indicate why the parents were so conservative. Instead, they ask, is it possible that a short childhood in a relatively small group, with a limited number of associates with whom one could learn and experiment, could have harmed the option to create real innovation?

Somel et al. (Reference Somel, Liu and Khaitobich2013) support the importance of long childhood. Referring to data on the rate of production of proteins in the brain due to different genes, they contend that the process of creating synapses (synaptogenesis) in the frontal cortex, the quantity of which has a major effect on the brain’s plasticity, takes place primarily between the ages of 3½ and 10. This period is the ‘window of opportunity’ in which many human cognitive abilities are developed. In chimpanzees and macaque monkeys this period is limited to a few months only. From the suggested Early Palaeolithic short childhood, the effect we can deduce regarding human cognitive ability is that of its possible bearing on a limited scope of innovation (Somel et al. Reference Somel, Liu and Khaitobich2013, 124). The biological perspective sheds light on the relative ‘stagnation’ in handaxe technology. On the attempt to ascribe the slow change in the form of tools to conformity caused by the early stage of cortical organisation, Bar-Yosef (Reference Bar Yosef2006, 483) writes that the explanation based on ‘predetermined solutions embedded in the technical “mind” of [the] individual who conformed to the social context of society’ is more applicable than the one based on brain development.

Demographic studies indicate that a clear link can be identified between the dynamics of culture – the stability of traditions and the development of variance within them – and demographic processes such as population size, composition, and distribution (Steele & Shennan Reference Steele and Shennan2009), although others, such as Vaesen et al. (Reference Vaesen, Collard, Cosgrove and Roebroeks2016) argue that population size does not explain past changes in cultural complexity. Richerson et al. (Reference Richerson, Boyd and Bettinger2009) maintain that if we assume that the development of practical novelties is a rare event, then the rate of innovations should be relatively limited in small populations. In such populations, practical innovations will disappear randomly due to the problem of information transmission. In relatively large populations there are more potential inventors, and the chance of incidental loss of innovation is relatively small. Premo and Kuhn (Reference Premo and Kuhn2010) assert that the stability of Lower Palaeolithic technology is not related to human limited cognitive ability, as other scholars claim, but is derived, rather, from the high extinction rate of small social groups that characterised this period. Nevertheless, the question remains: Why did extinctions limit transformations only in lithic technology and not in the other described technologies and life-history characteristics?

In summary, we have reviewed a variety of explanations, some mutually supportive, others mutually contradictory, for the handaxe ‘stagnation’ phenomenon. The basic problem with this variety of explanations is that they present theories that are considered to be valid in principle in other fields in which transformation and innovation occurred, such as the emergence of the Levallois method or the use of fire. Why, then, should the handaxe phenomenon be considered to differ from other fields of human behaviour? What was so unique to it or its use that led to its persistence for more than a million years?

PREFERRED CONSERVATISM AS A MAJOR DRIVE TOWARDS TECHNOLOGICAL PERSISTENCE

Here we engage with conservatism on two levels: the practical function of the handaxe; and the cognitive-social mechanism that entrenched the production and use of handaxes as a prolonged tradition. The term conservatism does not imply that humans resisted change; rather, it suggests that in this specific realm change was not perceived as an essential adaptive element. Conservatism, both social and biological, proves itself when the environment is reasonably stable and change is unnecessary. Under these circumstances the drive for innovation is relatively low and the modes of action that have proven themselves have an advantage over those that have not yet stood the test of time. Conservatism does not have to be expressed in all aspects of life. Many examples of conservatism concurrent with innovation are known (Lucas Reference Lucas2005, 83), and this may well be the case here. Such a state of affairs may be due to several reasons:

• ∙ Technological development in one field and not in another. For example, information technology compared to the relative ‘stagnation’ of internal combustion engine technology.

• ∙ The drive for adaptation in a particular field compared to relatively constant conditions in other fields. For example, the development of sophisticated weapons compared to the relative stagnation of rifle and hand grenade technologies.

• ∙ Fields in which conservatism is based on deep foundations compared to those in which it is not. For example, the conservatism of social or religious norms and codes compared to the innovative use of technology. This phenomenon is particularly prevalent in traditional and religious societies.

The Acheulean handaxe might fall under one of these categories. However, the specific question remains as to what were those areas of life in which the handaxe had an advantage? The solution may lie in one or a combination of two alternatives:

• ∙ The handaxe itself was functionally important, so its production and use gave a direct evolutionary/adaptive advantage over a very long period of time.

• ∙ For various reasons the manufacture and use of handaxes became a social norm (probably related to the first alternative), and the tendency to imitate the majority and/or to punish deviators preserved the norm for millennia.

Lycett (Reference Lycett2015) categorises selective biases that may act on artefact variation as ‘content biases’ (functional bias and aesthetic bias), ‘contextual biases’ (model- based biases based on prestige, success, similarity, etc), and frequency-based biases (conformity, saturation, and rarity). Here we suggest that conservatism was adopted and preferred due to a combination of biases that slowly shifted from functional (and aesthetic) preferences to conformity, as will be elaborated upon below.

THE FUNCTIONAL BASIS FOR CULTURAL CONSERVATISM – THE ROLE OF THE HANDAXE IN MEGAFAUNA PROCESSING

Most scholars would agree, we believe, that the available functional, technological, and experimental evidence suggests that the primary use of Lower Palaeolithic handaxes, as well as Middle Palaeolithic bifaces, lay in processing animal carcasses (eg, Claud et al. Reference Claud, Brenet, Maury and Mourre2009; Claud Reference Claud2008; Reference Claud2012; Jones Reference Jones1980; Keeley Reference Keeley1980,160–70; Machin et al. Reference Machin, Robert, Hosfield and Mithen2007; Mitchell Reference Mitchell1996; Solodenko et al. Reference Solodenko, Zupancich, Nunziante Cesaro, Marder, Lemorini, Barkai and Petraglia2015). It is true that in some cases handaxes were used in other tasks than in solely assisting the extraction of calories from different game taxa (eg, Domínguez-Rodrigo et al. Reference Domínguez-Rodrigo, Serrallonga, Juan-Tresserras, Alcala and Luque2001) and, thus, some see the handaxe as a multipurpose tool. However, the bulk of the available data indicates not only the repeated archaeological association of handaxes and processed animal parts, but also the efficiency and suitability of handaxes in skinning, cutting, defleshing, and dismembering carcasses, and in particular carcasses of large game taxa (eg, Jones Reference Jones1980;Reference Jones1981;Reference Jones1994; Key & Lycett Reference Key and Lycett2015; Reference Key and Lycett2016). It is also true that while handaxes are present at many Lower Palaeolithic sites associated with elephant and other large taxa remains, some multi- as well as single elephant carcass sites lack handaxes altogether (see Slodenko et al. Reference Solodenko, Zupancich, Nunziante Cesaro, Marder, Lemorini, Barkai and Petraglia2015 for details).

We do not discuss here a possible explanation for handaxes not having been found at those sites, and we do not claim that the only possible way of processing a large animal carcass was by using a handaxe. We do, however, offer an hypothesis regarding the repeated association of handaxes and very large game at Lower Palaeolithic sites in the Old World, coupled with the dependency of Palaeolithic humans on animal meat and fat (eg, Ben-Dor et al. Reference Ben-Dor, Gopher, Hershkovitz and Barkai2011; Reference Ben-Dor, Gopher and Barkai2016; Domínguez-Rodrigo & Pickering Reference Domínguez-Rodrigo and Pickering2017; Zink & Lieberman Reference Zink and Lieberman2016), and the intriguing production of handaxes made from elephant limb bones (Zutuvski & Barkai Reference Zutovski and Barkai2016 for details). While it is generally accepted that meat fueled the physiological developments in Homo erectus populations (eg, Aiello & Wheeler Reference Aiello and Wheeler1995; Domínguez-Rodrigo et al. Reference Domínguez-Rodrigo, Bunn, Mabulla, Baquedano, Uribelarrea, Pérez-González, Gidna, Yravedra, Diez-Martin, Egeland, Barba, Arriaza, Organista and Ansón2014; Pontzer et al. Reference Pontzer, Brown, Raichlen, Dunsworth, Hare, Walker and Luke2016), we suggest that greater emphasis should be placed on the role of fat and the significance of animals capable of supplying large quantities of fat year round (Ben-Dor et al. Reference Ben-Dor, Gopher, Hershkovitz and Barkai2011; Reference Ben-Dor, Gopher and Barkai2016). Elephants and mammoths are such animals, and thus we argue that the dependency of early humans on the caloric contribution of fat and meat, in addition to plant-based calories (eg, Melamed et al. Reference Melamed, Kislev, Geffen, Lev-Yadun and Goren-Inbar2016), led to the preference for procuring calories from elephants and mammoths, when available. Other large prey (rhinoceros, hippopotamus, wild cattle, and wild horse) are also important contributors of fat and meat, and these taxa were of course regularly exploited by early humans as well. However, no animal matched the extraordinary package of fat and meat as that to be found in the elephant and mammoth. Smaller taxa such as deer and gazelles, among the ungulates, as well as tortoises, rabbits, and birds, were also a source of calories whenever possible, but again none of these matches the ideal food package represented by the proboscidea.

Skinning, cutting, defleshing, and dismembering elephants and mammoths is a tedious and demanding task (eg, Gingerich & Stanford Reference Gingerich and Stanford2016). The presence of proboscidea remains bearing cut marks at Palaeolithic sites (see Slodenko et al. Reference Solodenko, Zupancich, Nunziante Cesaro, Marder, Lemorini, Barkai and Petraglia2015 for details) as well as the butchered elephant skull from the site of Gesher Benot Ya’aqov, associated with many handaxes (Goren-Inbar et al. Reference Goren-Inbar, Lister, Werker and Chech1994), supports our contention regarding the link between Lower Palaeolithic humans, elephants, and handaxes. The same holds true for a biface bearing fat residue from the Acheulean site of Revadim, Israel (Slodenko et al. Reference Solodenko, Zupancich, Nunziante Cesaro, Marder, Lemorini, Barkai and Petraglia2015). The presence of butchered elephant/mammoth remains at many Palaeolithic sites worldwide (eg, Agam and Barkai Reference Agam and Barkai2016; Blasco et al. Reference Blasco, Jordi, Fernández-Peris, Arsuaga, Bermúdez de Castro and Carbonell2013; Germonpré et al. Reference Germonpré, Sablin, Khlopachev and Grigorieva2008; Iakovleva et al. Reference Iakovleva, Djindjian, Maschenko, Konik and Moigne2012; Kufel-Diakowska et al. Reference Kufel-Diakowska, Wilczyński, Wojtal and Sobczyk2016; Rabinovich et al. Reference Rabinovich, Ackermann, Aladjem, Barkai, Biton, Milevski, Solodenko and Marder2012; Smith Reference Smith2015) suggests that elephants played a major role in the early human diet and adaptation (but see Lupo & Schmitt Reference Lupo and Schmitt2016 and Smith Reference Smith2015). Direct evidence of proboscidean consumption is also provided by isotopic studies, indicating a significant dependence upon mammoths by early humans in Europe (e.g. Bocherens Reference Bocherens2011; Bocherens et al. Reference Bocherens, Drucker, Germonpre, Lázničková-Galetová, Naito, Wissing, Brůžek and Oliva2015; Naito et al. Reference Naito, Chikaraishi, Drucker, Ohkouchi, Semal, Wißing and Bocherens2016).

The importance of proboscideans in the Palaeolithic diet is further stressed through cases in which selected elephant body parts were carried into Palaeolithic caves (eg, Blasco et al. Reference Blasco, Jordi, Fernández-Peris, Arsuaga, Bermúdez de Castro and Carbonell2013; Germonpré et al. Reference Germonpré, Udrescu and Fiers2014; Zhang et al. Reference Zhang, Stiner, Dennell, Wang, Zhang and Gao2010), implying their high nutritional value (especially regarding elephant heads, see Agam and Barkai Reference Agam and Barkai2016), along with the social and symbolic roles that certainly could have accompanied such an activity. We do not delve here into the question of whether proboscideans were procured by hunting, scavenging, or both, but suggest in brief that, in our opinion (Agam and Barkai submitted), relevant archaeological, ethnographic, and ethno-historic evidence points in favor of hunting as a relevant elephant/mammoth procurement strategy. The scope of this article does not allow us also to engage with the ways in which Palaeolithic groups dealt with this enormous ‘food package’, but we hope to be able to develop this line of inquiry elsewhere.

We suggest that handaxes were efficient and effective tools in processing large carcasses, enabling the removal of large quantities of fat and meat and the separation of body parts in order to manipulate and transport them. The handaxe allows the application of considerable force and leverage during cutting and dismembering, and its continuous and mostly curved and sharp working edge is ideal for massive and intensive meat and fat processing tasks (eg, Key & Lycett Reference Key and Lycett2015; Reference Key and Lycett2016) (Fig. 2). Moreover, handaxes could be re-honed in order to prolong the use of the tool for continuous operations, such as the processing of very large game (eg, Claud Reference Claud2012). We thus see the handaxe as the primary tool that assisted butchery during Lower Palaeolithic times, and in particular the processing of large game such as the elephant. The intriguing production of handaxes made of elephant bones might serve as another clue, emphasising the possible role of these components within the cosmology of the groups that used stone handaxes in their preparation for the consumption of elephants (see Zutuvski & Barkai Reference Zutovski and Barkai2016). Last but not least is the chronological and geographical connection between elephants/mammoths and handaxes. We suggest that these two go hand in hand, and that when megafauna no longer comprised part of the diet, handaxes/bifaces ceased to be produced and used. It is our contention that the central role of handaxes and large game in Lower Palaeolithic adaptation is of pivotal significance, and that it is the role of handaxes in processing these large ‘food packages’ that ensured their long service during Lower Palaeolithic times.

Fig. 2 An experiment in using flint handaxes in butchering operations (courtesy of Ruth Blasco and Jordi Rosell)

Within the framework of our hypothesis, it is interesting to recall Bar-Yosef’s suggestion that, considering the variety of difficulties encountered by humans as they spread from Africa to Asia and Europe, it is not surprising that the handaxe – as a useful and effective tool specifically employed for cutting raw meat – persisted over such a long period: ‘It is against this background that we should view the conservation of knapping techniques and the retention of tool morphotypes like the bifaces that served, like Swiss Army Knives, as multi-purpose tools, and were undoubtedly essential in chopping meat into small pieces consumed (and digested) raw’ (Bar Yosef Reference Bar Yosef2006, 490).

HANDAXE VARIABILITY: ‘INSIDE THE BOX’ MODIFICATIONS

‘Variability’ and ‘variation’ are the major terms used by those who subscribe to the view of a dynamic and variable process over that of ‘stagnation’ in handaxe persistence during Palaeolithic times. A recent publication of several handaxe assemblages from a Lower Palaeolithic site in Syria offers a good example of the scale of variability in handaxe production during different Acheulean human occupations (Jagher Reference Jagher2016). Consistent with our proposal of functional-based conservatism, we refer to the recent understanding that function is not substantially affected by morphological variation.

McNabb and Cole (Reference McNabb and Cole2015) argue that handaxe variability reflects situational/local symmetry and refinement and that no gradual slope of advancement can be seen in Acheulean material culture. They propose the term ‘variable equilibrium’ to describe the phenomenon of variability within long periods of apparent stasis.

Key and Lycett (Reference Key and Lycett2016) conducted a large-scale experiment in handaxe cutting efficiency (n=500 handaxes) and stated that variability in size and shape does not necessarily have a strong impact on the cutting effectiveness.

In a recent experiment focusing on the role of copying variance in handaxe form, Schillinger et al. (Reference Schillinger, Mesoudi and Lycett2016) argue that what seems to be cultural-based artefact variability may not result from an ‘intent’ or ‘mental template’ but from behavioural differences among individual artisans that over time developed into ‘visibly distinct traditions’.

In another recent study on the role of micro-evolutionary processes in handaxe variation, while taking into account factors of raw material, copying errors, and their relationship to mechanisms of social learning, Lycett et al. (Reference Lycett, Schillinger, Eren, von Cramon-Taubadel and Mesoudi2015) contend that handaxe variation was probably both generated and constrained by those opposing factors. We concur with these ideas, with the addition of the social factors.

FUNCTION LEADS THE WAY TO A NEW SOCIAL NORM

In this section we review a list of possible reasons that might have led to the transformation of the original functional role of the handaxe (including its variation) into a dual role, combining the practical with the social.

Sharon (Reference Sharon2008) studied the impact of raw material on Acheulean large flake production and suggested that the phenomenon that we define as ‘stasis’ – a similar form regardless of the original shape, size, and type of raw material – in fact reflects inventiveness and resourcefulness. The conclusion to be drawn from these data is that raw material availability, type, shape, and technological constraints were not the primary factors dictating the characteristics of handaxes. This leads to the possibility that the main consideration guiding the Acheulean knapper was a functional and/or cultural preference. Experimental knapping also supports the notion that early humans had a preconception of the desired end product of the reduction sequence (Eren et al. Reference Eren, Roos, Story, von Cramon-Taubadel and Lycett2014).

Another functional realm of the handaxe was suggested by Kohn and Mithen (Reference Kohn and Mithen1999), who contended that handaxes might have played a role in Lower Palaeolithic mating systems by demonstrating the overall cognitive, physical, and mental competency of males in order to be selected by females for gene exchange. Such a mechanism would have led to preferred cultural conservatism. We may be dealing here with the conservatism of a social code that developed in human society through many generations of mate selection based on handaxe production and use (following the Handicap Principle), and eventually manifested in the framework of technological conservatism. It is of interest to note that Lower Palaeolithic quarries and workshops in Isampur, India: ‘… presents tentative evidence for shared intentions and cooperation in biface manufacture’ (Shipton Reference Shipton2013, 63 and references within). Ethnographic studies too reveal that large-scale quarrying activity might be characterised by cooperation (eg, Burton Reference Burton1984; Hampton Reference Hampton1999, 226–32, 256–62).

We suggest that handaxe production might have been a form of preferred social activity, replaced by later stone tool making methods and technologies (Levallois, blades, etc), storytelling around the campfire, rituals, and other mechanisms. The mechanism of handaxe production might explain its enduring persistence. Hunting big game, aside from its major contribution to diet and survival, is also viewed as a preferred male social activity (eg, Speth Reference Speth2010 and references therein). Handaxe production may be another example of male ‘display’ and technological ‘gadgetry’ based on the functional necessity of this item in the extraction of calories from big game (see Hawkes et al. Reference Hawkes, O’Connell and Blurton Jones2014 and references within).

Machin touches upon the basic human cognitive tendency for aesthetics. Aesthetic objects generate emotional and intellectual pleasure (Machin Reference Machin2009, 48), and symmetrical handaxes may have had a combined aesthetic and functional advantage (Machin et al. Reference Machin, Robert, Hosfield and Mithen2007). Gowlett (Reference Gowlett2011) argues that a constant proportion in Acheulean handaxes, in many cases the 0.61/1 ratio or the ‘golden ratio’ (the proportion preferred in the natural world, including an aesthetic measure by humans), testifies to the deep roots of this human trait. He also suggests that the difficult to achieve elongation that characterises 5–10% of the handaxes from 1.75 Mya, is the outcome of both functionality and symbolic value (Gowlett Reference Gowlett2013). This argument can be added to the preferred mate selection and preferred social activity hypotheses, with particular shape/size perhaps constituting personal and/or group markers.

In some specific and interesting cases ‘imitations’ of the typical stone handaxes were made from elephant limb bones (see Zutovski & Barkai Reference Zutovski and Barkai2016 for an updated account). This remarkable Acheulean trait combined two of the most fundamental elements found at many Lower Palaeolithic sites: namely, large game and bifaces – and may express a cosmological connection between Acheulean subsistence and lifeways, closing an ontological circle by producing bone handaxes from the remains of elephants that might have been processed using stone handaxes.

Assuming that the handaxe had one or more of the above-mentioned functions, in addition to its practical role in processing animal carcasses, we need to explore the learning/knowledge transmission mechanism that cemented its central role in human adaptation during the Lower Palaeolithic.

Studies in cognitive psychology on the type of social learning called ‘conservatism transmission’ – an adaptive mechanism aimed at acquiring knowledge by observing the behaviour of others and the mental state that underlies their behaviour – offer a possible explanation. Henrich and Boyd (Reference Henrich and Boyd1998) suggested that the psychological bias to ‘acquire’ behaviour, which is common to most members of a group (‘following the herd’), has an advantage over social solitary learning in a wide range of situations. One possible consequence of this learning/transmission mechanism is the creation of long-term boundaries between groups. This type of learning/transmission mechanism can explain the persistence of certain human behaviours in a particular group, including the production and use of a specific technology. On the other hand, the possible creation of boundaries between groups might impede the wider inter-group transmission of knowledge. In the case of the handaxe, the combination of long-term persistence and wide geographic distribution suggests that this mechanism does not provide an appropriate explanation. However, one cannot rule out the possibility that the emphasis in research on exclusively identifying the Acheulean culture with handaxes has led to less attention being paid to Lower Palaeolithic sites devoid of handaxes (eg, Bizat Ruhama in Israel, Grand Dolina in Atapuerca, and the Clactonian in Britain, see Zaidner et al. Reference Zaidner, Yeshurun and Mallol2010; García-Medrano et al. Reference García-Medrano, Ollé, Mosquera, Cáceres and Carbonell2015 and Mithen Reference Mithen1996, respectively).Thus future research may prove that the pattern of greater Acheulean variability or ‘sub-cultures’ actually fits the model presented above.

Tehrani and Riede (Reference Tehrani and Riede2008), who claim that stone knapping was too complex to be transferred through imitation, emphasise the role played by active teaching. Based on ethnographically documented traditions, including weaving, stone-knapping, and foraging, they state that teaching has been an important mechanism in material culture transmission since at least the Lower Palaeolithic. They also argue that, through teaching, highly complex forms can be expected to survive for very long periods since both the donors and the recipients actively collaborate in knowledge transfer. We strongly believe that such a scenario is applicable for the Acheulean handaxes, as most scholars agree its production could not be transmitted by imitation only.

The following human traits enhance conformity and conservatism and should be taken into account in this discussion:

1. 1. Strong reciprocity: ‘A strong reciprocator is predisposed to cooperate with others and punish non-cooperators, even when this behavior cannot be justified in terms of self-interest, extended kinship, or reciprocal altruism’ (Gintis Reference Gintis2000);

2. 2. Homophily: The tendency for individuals to associate and bond with others like themselves (Flynn et al. Reference Flynn, Reagans and Guillory2010);

3. 3. The need for closure (NFC), which reflects an aversion to ambiguity and uncertainty as well as a preference for firm, definitive answers to questions (Kruglanski & Webster Reference Kruglanski and Webster1996). Persons with high NFC are more motivated to reach agreement with their peers and are more disturbed by violations of social norms (Flynn et al. Reference Flynn, Reagans and Guillory2010);

4. 4. The chameleon effect: the unconscious mimicry of the postures, mannerisms, facial expressions, and other behaviours of one’s interaction partners, such that one’s behaviour passively and unintentionally transforms to match that of others in one’s social environment. The chameleon effect might have played a role in human evolution by allowing individuals to maintain harmonious relationships with fellow group members (Chartrand & Bargh Reference Chartrand and Bargh1999; see also Lakin et al. Reference Lakin, Jefferis, Cheng and Chartrand2003).

An examination of the conservativeness/flexibility of 47 cultural traits in 277 African societies revealed that the traits affecting family structure and kinship had demonstrated a high degree of conservation over generations. These traits, transmitted by family members, indicate that cultural transmission in the family is the most conservative mechanism (Guglielmino et al. Reference Guglielmino, Viganotti, Hewlett and Cavalli-Sforza1995). The dominance of vertical transmission was also observed in North American Native Peoples, where learning from group members was a more important process than learning from members of other groups (Mathew & Perreault Reference Mathew and Perreault2015). Traits that require the expertise of a specialised mode of subsistence were also found to be vertically transmitted in Austronesian cultures (Mace & Jordan Reference Mace and Jordan2011). In sum, these data reflect the substantial support for preferred cultural conservatism.

A direct correlation exists between the bias towards conservatism and evolving ‘traditions’ in a variety of animals, such as birds, rodents, and Japanese Macaque monkeys (for a review see Jablonka & Lamb Reference Jablonka and Lamb2005, 155–91), and thus the transmission of human culture is much more elaborated than those of chimpanzees. As for human material culture, Eerkens and Lipo (Reference Eerkens and Lipo2007) argue that employing the conservatism transmission approach explains many phenomena in the archeological record. Claidière and Whiten (Reference Claidiere and Whiten2012) link sociological research to the study of animal behaviour. They divided the issue of conformity into two sub-issues: information/knowledge conformity (for acquiring non-social information in order to gain an adaptive edge in new environments); and normative conformity (for acquiring social information in order to facilitate cooperative relationships with other members of the group). Conformity and punishment evolved concomitantly in large groups and enabled improved inter-group cooperation because conformity reduces variance, which is the basis of disagreement, and at the same time it supports punishment. Punishment, in turn, protects the group from deviations and gives conformists an advantage over ‘independent’ imitators (Boyd & Richardson Reference Boyd and Richardson1992; Guzman et al. Reference Guzman, Rodriguez-Sickert and Rowthorn2007). It should be noted that a willingness of societies to risk costly punishment has been observed around the globe (Henrich et al. Reference Henrich, McElreath, Ensminger, Barr, Barrett, Bolyanatz, Cardenas, Gurven, Gwako, Henrich, Lesorogol, Marlowe, Tracer and Ziker2006). It is generally accepted that norms provide an evolutionary advantage to individuals (Kameda et al. Reference Kameda, Takezawa and Hastie2005). A study of norm enforcement in Ju/‘hoansi hunter-gatherers revealed that norms are obeyed, and the imposition of penalties on violators occurs even when such costly behaviour cannot be explained by immediate preferences. Wiessner (Reference Wiessner2005) suggests that one of the motives for this is the need to maintain ‘industrial peace’ in the social group. Punishment of norm violators is a mechanism for maintaining social cohesion and is central in hunter-gatherer societies. Regarding Acheulean handaxe persistence, we suggest that the bias to imitate majority behaviour that then evolved into social norms may provide a plausible explanation.

THE HANDAXE & THE CHOPSTICK – A TEST-CASE FOR PREFERRED CULTURAL CONSERVATISM BASED ON FUNCTION, LEADING TO THE CREATION OF A SOCIAL NORM

In his book Chopsticks: A cultural and culinary history, Wang (Reference Wang2015) describes in depth a phenomenon not so very different to what we have just described concerning the handaxe. Forty-two bone sticks found in Neolithic Longqiuzhuang ruins in present-day Gaoyou, Jiangssu, dated to 6600–5500 BCE, are believed by some scholars to be the earliest recorded chopsticks, although others suggest that they were used as hairpins (Wang Reference Wang2015, 16–17). It was only in the Bronze Age, or during the Shang dynasty (c. 1600–1046 BCE), that the Chinese began using chopsticks to prepare and eat food. Bronze pieces found at two sites in southern China (Anhui) and south-west China (Yunnan) may have been originally employed in cooking – stirring and mixing, and only later on in feeding. The earliest ivory chopsticks were found in Changyang, Hubei, dated to the Zhou period (1045–256 BCE). The spoon was the primary eating implement in ancient China, but due to the broad appeal and increasing variety of floured-wheat foods, it lost its primacy across China to the chopsticks. Later on, the spreading influence of the Tang culture in Asia extended the use of chopsticks to the north (Mongolian pastureland), north-east, and east (Korean Peninsula and the Japanese islands) and south (the Indochina Peninsula). ‘A chopsticks cultural sphere thus began to take shape, albeit with discernible variation in time and space’ (Wang Reference Wang2015, 66). Was the ‘Handaxe cultural sphere’ the first of many later similar phenomena?

Wang goes on to describe how chopsticks were (and still are) used as popular wedding gifts and in wedding ceremonies, and in celebrating happy occasions like birthdays and sad ones like funerals. The Japanese call the utensil ‘the sticks for one’s life’, for chopsticks are, for the Japanese as well as for other Asians, a symbol of life. As part of acquiring cultural meaning, chopsticks, usually made of bamboo or cheap wood, are sometimes also made of rare and expensive materials (depending on geography) such as gold, silver, copper, rhinoceros horn, deer antler, ivory, ebony, mahogany, and the most precious one – jade (Wang Reference Wang2015, 120–43). Chopstick design also varies in length (18–33 cm in Tang China), the shape of the top (rounded or four-sided), ‘two-ended’ vs ‘one-ended’, and more (Wang Reference Wang2015, 77–84). Altogether, we suggest that the phenomenon described in the case of chopsticks has some parallels with that of the handaxe – a tool that was originally developed to best fit an essential function but which over time gained social and cultural meanings, resulting in a basic shape that persisted over long periods, combined with multiple variations in size, material, and level of finish.