Review article
Variability in an early hominin percussive tradition: the Acheulean versus cultural variation in modern chimpanzee artefacts
Abstract
Percussion makes a vital link between the activities of early human ancestors and other animals in tool-use and tool-making. Far more of the early human actions are preserved as archaeology, since the percussion was largely used for making hard tools of stone, rather than for direct access to food. Both primate tools and early hominin tools, however, offer a means to exploring variability in material culture, a strong focus of interest in recent primate studies. This paper charts such variability in the Acheulean, the longest-lasting tool tradition, extant form about 1.7 to about 0.1 Ma, and well known for its characteristic handaxes. The paper concentrates on the African record, although the Acheulean was also known in Europe and Asia. It uses principal components and discriminant analysis to examine the measurements from 66 assemblages (whole toolkits), and from 18 sets of handaxes. Its review of evidence confirms that there is deep-seated pattern in the variation, with variability within a site complex often matching or exceeding that between sites far distant in space and time. Current techniques of study allow comparisons of handaxes far more easily than for other components, stressing a need to develop common practice in measurement and analysis. The data suggest, however, that a higher proportion of traits recurs widely in Acheulean toolkits than in the chimpanzee record.
1. Introduction
Percussion strikes a vital common point in linking the cultural activities and toolkits of humans, primates and other animals. But there is an immediate asymmetry in what we see: most percussion by primates is aimed to achieve an immediate objective, but the human activity is often directed towards shaping new tools. The variety of tools and toolkits in use by chimpanzees is now well documented, and so is their cultural variation within and between communities [1–5]. Primatologists often ask whether it is possible to pick out a similar cultural variation in the deep past of hominin evolution. This would be a very important goal. If so, the prime evidence would be not the variety of organic materials that are dominant in the chimpanzee or capuchin record, but the hard outputs of percussion that survive in the long-term record. This paper attempts to make such a comparison. To do that with common purpose between disciplines we need to drop as far as possible histories and terminologies that form barriers to enquiry.
The main example in this paper is the Acheulean tool tradition, which is the longest percussive facies enduring in the hominin record, lasting from about 1.7 to 0.1 Ma (i.e. more than 50% of all recorded tool-making, and probably somewhat longer than the preceding Oldowan) [6–9]. This review must introduce at least two terms: handaxes are the defining tool of the Acheulean. They are large hand tools of stone averaging 10–20 cm in length (figure 1) and have been described and discussed over a long period [10–14]. Handaxes and allied forms are often termed ‘bifaces' as a general class. ‘Assemblage’ is the most neutral term for describing the collection of material culture that comes from one place at one time [15] and is equally applicable to objects made or used by non-human participants.
Figure 1. An Acheulean handaxe photographed in the field at Cornelia, South Africa: plan and side view. Its measurements of L 177 × B 93 × T 37 mm are fairly typical for African site complexes. (Online version in colour.)
Apart from its immensely long time duration, the Acheulean was also geographically widespread, occurring across Africa (figure 2), Europe and much of Asia. The primate record with the most artefacts and largest distribution for comparison of cultural traits is undoubtedly that of the common chimpanzees, Pan troglodytes [1–4]. Their material record stretches across ca 4000 km in Africa and has a time depth that is largely contemporary, but which may stretch to as much as 4000 years in the case of the Panda tree site in the Tai Forest of Ivory Coast [16]. Several important potential differences are immediately apparent: the chimpanzee record clearly shows contemporary cultural variation. Is that so for the hominins? Functions of tools are clearly evident for the chimpanzees, because they can be observed. Is that the case for the hominins? Chimpanzees have used quite large quantities of tools, and toolsets on some sites [2]. Is that also so for the hominins? Practices that are known in one area for chimpanzees are sometimes absent in another (e.g. nut-cracking). Would this also be the case in the hominin record?
Figure 2. The distribution of the Acheulean in Africa following Clark [15], indicating some major sites and site complexes mentioned in the text. The grey area indicates the approximate recent distribution of African apes.
2. The Acheulean tradition
This account focuses chiefly on the Acheulean in Africa, rather than Asia or Europe. In this way, it takes in the full time depth of the Acheulean (very few sites much older than 1 Myr are known outside Africa). Within the continent, there is limited ecological comparability with African apes, which inhabit very different habitats from hominins, although there can be overlaps in the use of food resources [17]. In total, there is a great deal of the Acheulean in the form of collections made across the length and breadth of the continent [18] (figure 2), with occurrences exceeding the cases of chimpanzee tool-making. In addition to the numerous stray finds and minor sites, there are also some 20 Acheulean site complexes in Africa where major work has been carried out (table 1). Also relevant here are site complexes in the Middle East such as Gesher Benot Ya'aqov and ‘Ubeidiya [62,63], and further South African sites such as Cave of the Hearths and Wonderwerk Cave [64,65].
| country | approx. age (Myr) | main publication | |
|---|---|---|---|
| Casablanca | Morocco | 0.3–0.7 | [19–21] |
| Tighenif | Algeria | ∼0.5 | [22,23] |
| Tabalbalat | Algeria | ∼0.5 | [24] |
| Khor Abu Anga | Sudan | ∼0.5 | [25] |
| Melka Kunture | Ethiopia | ∼0.7–1.2 | [26–28] |
| Gadeb | Ethiopia | 1.2 | [29,30] |
| Mieso | Ethiopia | 0.2–0.3 | [31,32] |
| Konso Gardula | Ethiopia | 0.8–1.7 | [7] |
| Buia | Eritrea | 1.0 | [33] |
| Kapthurin | Kenya | 0.3 | [34–36] |
| Kilombe | Kenya | 1.0 | [37–39] |
| Kariandusi | Kenya | 1.0 | [40–42] |
| Isenya (Isinya) | Kenya | 1.0 | [42,43] |
| Olorgesailie | Kenya | 0.5–0.9 | [13,44] |
| Olduvai Gorge | Tanzania | 0.2–1.5 | [12,45,46] |
| Nsongezi | Uganda | 0.3–0.5? | [47] |
| Isimila | Tanzania | ∼0.5 | [48,49] |
| Peninj | Tanzania | 1.4 | [50,51] |
| La Kamoa | Congo | ∼0.4 | [52] |
| Kalambo Falls | Zambia | ∼0.4 | [53–56] |
| Canteen Koppie | South Africa | ∼0.5 | [57] |
| Amanzi | South Africa | ?0.5 | [58] |
| Sterkfontein | South Africa | ∼1.4 | [59] |
| Cornelia | South Africa | 0.5–1.0 | [60] |
| Montagu Cave | South Africa | ∼0.3–0.5 | [61] |
Naturally, to take the output from more than a million years and to compare it with the contemporaneity of chimpanzee cultures strains analogy. Glynn Isaac adopted a way of comparison that can tackle this problem in an interesting way (figure 3): the local variation within a near-contemporaneous site complex can be compared with the variation between site complexes that are more distant [13]. Of course, that can only be done if the variation between sites is not excessive, so that the comparison is not of ‘apples' and ‘pears'. But an essential feature of the Acheulean (it will be shown) is the recurrence of similar elements in a ‘variable sameness'.
Figure 3. Acheulean sites occur singly, in chronological series (as at Olduvai) and in paenecontemporaneous clusters (as at Olorgesailie). Even without chronological precision it is possible to compare variability within site complexes and variability between sites and site complexes.
3. The Acheulean toolkit
(a) The toolkit
In terms of percussion, the Acheulean includes tools that make the ‘framework’ of percussion (hammerstones and anvils) and the artefacts themselves, which are all made by percussion. They fall into five main groups (figure 4):
— large elongate tools (the bifaces),
— percussion devices (hammerstones and anvils),
— heavy-duty compact tools,
— sharp flake tools and other products of flaking, potentially usable.
Figure 4. The main chains of activity typically involved in the manufacture of an Acheulean toolkit. Hominins often made bifaces from large flakes struck from ‘giant cores', then finishing them with secondary working; in a largely separate, parallel process, smaller cores—sometimes shaped to be tools—yield flakes, some of them also used as tools. (Online version in colour.)
This review attempts the exercise of making comparisons through using straightforward multivariate dimension-reducing techniques. It uses Principal Components Analysis (PCA) to look at whole-group collections; then Principal Components and Discriminant Analysis (DA) to examine variation in the handaxes (the main category of shaped tools).
(b) The dataset
East and South Africa are richest in investigated site complexes, although they occur in North Africa too. Some of them are very tightly grouped in time, but others represent long columns through time. The most useful setting is one where there is evidence for a number of different localities in a site complex being approximately contemporaneous. This configuration is seen for example at Olorgesailie in Kenya, and Kalambo Falls in Zambia [13,50,53,54]. It allows a research design of comparing the variations within one complex with those between complexes, factoring in also those long columns of record that are occasionally available from complexes such as Olduvai Gorge [12,45,46]. In addition to the site complexes listed in table 1, data have also been used from Arkin 8 in Nubia; East Turkana (where rare Acheulean sites occur with the later Oldowan-like sites); Latamne in Syria; and Lochard and Broken Hill in southern Africa [49,66–68].
4. Principal components analysis of assemblages
In this comparison, the groupings of material are brought together from more than 60 assemblages (drawn from 18 sites complexes or sites), following an approach first used by Isaac and Kurashina [13,69]—the idea is to analyse whole assemblages rather than one class such as handaxes. PCA is well known for allowing a reduction of dimensions in the data by calculating a new set of variables in which variance is arranged in descending order [70]. If the material is divided into 12 categories of artefacts in a common framework, then on an assumption of random distribution and membership, each variable would represent approximately 8.5% of the total variance. Among these assemblages, PC1 and PC2 are able together to account for about 40% of variance, suggesting a strong degree of common patterning in the material, despite the wide geographical and chronological spread, and the numbers of scholars interpreting their taxonomy.
A plot of PC1 and PC2 (figure 5) produces a scatter in which assemblages dominated by ‘heavy’ forms concentrate on the left, those by handaxes on the right, and those by small tools at the bottom. Bearing in mind that more than half of the overall variance does not feature here, it is still striking that:
— the variability in composition within some major site complexes overlaps with other complexes and sites, even where a single site complex tends to occupy a distinct area of the plot; and
— the overlaps include material originally made in the classifications of different workers, and so cannot be ascribed to ‘archaeological manufacture’ (e.g. assemblages classified by Mary Leakey that are rare in handaxes (her Developed Oldowan B [12]) appear on the left, with some other very early Acheulean described by other authors, but her ‘classic’ Acheulean appears within the main group of Acheulean assemblages as classified by other authors).
Figure 5. Principal components analysis of 66 Acheulean assemblages. PC1 and PC2 together account for about 40% of the variance in the original dataset, which was based on the categories: handaxes, cleavers, knives, large scrapers, discoids, core scrapers, picks, choppers, spheroids/polyhedrons, other large tools, small scrapers and other small tools.
This analysis attempted to look at gross pattern across whole collections or assemblages, but it is also possible to examine individual classes of the tools.
5. Comparisons of bifaces by principal components and discriminant analysis
Acheulean bifaces have attracted a great deal of attention in analysis in recent years [71–86], so much so that the handaxe has become an icon of the early past. In Africa, and parts of Asia and Europe, the bifaces are the principal percussion product of the stone toolkit, made through the striking of large primary flakes of the order of 10–20 cm long, and then converted into the final product by secondary working.
The bifaces are a broad class. A general analogy might be with chimpanzee stick and stem tools, which are used for various functions of dipping, thrusting and pounding [1,2,87,88]. If their uses were not observed, but somehow they were preserved, they might all be grouped together, but structure within the group might offer some insights into the presence of specialized tools with particular functions. In the scheme used here, handaxes, cleavers, picks and knives are classified as separate classes.
PCA or DA can be applied to examining pattern within the bifaces. The approach used here is ‘traditional’ in that it uses measuring systems applied by scholars over a long period [10,11,13]. PCA can be applied in various ways, either to individual assemblages or to whole datasets, focusing on the artefacts or relationships of variables. This analysis treats all the individual bifaces from 23 assemblages (from 18 site complexes). The comparison has a structure, in that about half are based on the site complex of Kilombe and are mainly ‘paenecontemporaneous' (Isaac's term for material of broadly the same age [13]); the remainder are from other sites, but in several cases in paired assemblages.
From the start, it is plain that there are enormous overlaps between groups of material in terms of their basic measurements (electronic supplementary material): that is, bifaces are bifaces. In the analysis, PC1 accounts for around of 70% of variance, and PC2 for 15%. It is known that PC1 largely represents size variation, but it also includes morphological information about other variables [73]. The pattern once again shows clearly that variation within site complexes can be as great as between them. There is a broad cluster of the Kilombe assemblages, but they overlap with numbers of assemblages from other areas. Again, pairs from sites such as Kariandusi and Kalambo Falls are quite widely separated: the two from Kariandusi fall on either side of the Kilombe group. Sites distinctive for their many large and thick bifaces appear to the top right in figure 6. They include the Kilombe Z assemblage, previously noted as unusually different from the rest of Kilombe material in its pattern of allometry [73].
Figure 6. PCA of Acheulean bifaces from 18 sites, based on 11 variables measured from individual bifaces (length, breadth, thickness, five other planform variables and three further thickness variables: see the electronic supplementary material). KAR, Kariandusi; COR, Cornelia; KF, Kalambo Falls; V, Vaal; STIC, STIC, Casablanca; KIL, Kilombe.
DA represents a completely different approach to the same data, as it demands the prior designation of groups, and then seeks functions that best discriminate between them. The results, however, are remarkably similar, except that PC1 appears to correspond to DF2, and PC2 to DF1. If these were transposed, the two scatter diagrams (figures 6 and 7) would be very similar.
Figure 7. DA based on the same dataset of Acheulean bifaces as figure 6. The analysis operates from designated groups, rather than the series of all individual bifaces as in PCA, but finds very similar pattern. Note how pairs of assemblages from the same site complex are often widely separated.
DA is useful in allowing group (i.e. site) centroids to be portrayed on a diagram. Often the technique is also used for classification, in which case its success can be tested in classifying cases back to their original group. That approach has little chance with this many groups because so many of the bifaces are so similar in morphology from site to site. Taking the group of Kilombe, EH (107 specimens), only 17 are classified to that assemblage, and only 59 are reclassified to any Kilombe assemblage. A more restricted analysis is more successful: analysing just Kariandusi (obsidian), Kariandusi (lava), Kalambo Falls A6 and Kalambo Falls B4—four assemblages from east and southern Africa—the rates of success in reclassification are: 46 out of 54; 43 out of 73; 9 out of 24; and 33 out of 45, respectively: an overall rate of 66.8% for the 196 specimens.
In this light, the lesson of these analyses appears to be that there is something distinctive about each biface locality, to the point that group centroids can be distinguished on the basis of size and morphology. But there are also such great similarities that local variation in the bifaces within a site complex often exceeds variation between far distant sites. From their measurements, most bifaces have a good chance of being classified into some site other than their own.
6. Small and large artefacts
Although the effort to make multivariate comparisons can be worthwhile, much other information can be drawn out from simple comparisons. Most artefacts in the African Acheulean are the result of direct percussion of flakes of various lengths. The investment in the making of bifaces—or the study of bifaces—ought not to overshadow the probable importance of smaller flake tools. The presence of scrapers and other small tools is frequently recorded. Unfortunately, there is little common approach to presenting results. Isaac set an excellent example with histograms (figure 8; see also [13], fig. 58). Subsequently there has been disappointingly little effort to compare the smaller tools, probably because they seem ‘casual’, unstandardized, and therefore not very interesting unless there is some definite link with their function (which usually there is not). Bifaces are relatively highly standardized in morphology, but occur in a great range of lengths and weights. Rather like modern screwdrivers, or kitchen knives, each size or shape may be appropriate to a particular task [89]. In small tools, there is quite likely a tighter size focus, but it is not certain whether there is higher size standardization, because there is lower morphological standardization.
Figure 8. Large and small artefact histogram (length in mm). This Acheulean bimodal pattern–of smaller flake tools and large bifaces–appears to be typical of many sites, but published data rarely allow the presentation of full histograms/bar charts. (Olorgesailie data after Isaac [13, fig. 58], and Kilombe biface data–shown by dotted line–author, see supplementary information). The Kilombe flake tool spectrum (not shown) is almost identical to that for Olorgesailie. (Olorgesailie flake tools N = 857, bifaces 1034; Kilombe bifaces N = 654).
7. Discussion
These analyses have been executed deliberately without first spelling out the many difficulties that are entailed. Archaeological detail, it seems, often deters scholars in other disciplines, but some points can now be explored. The ideal is sure: we ought to be able to look at the cultural variation in modern primate tools, and compare something similar in the early archaeological record. After all, far more tools are available, and huge efforts have gone into describing them. In archaeology, however, we lack two things that are central to studying tool-use by modern animals: one is knowledge of who does what and with which tool; the other is reliable internal timescales (i.e. how long did this activity go on here? Similar problems are potentially present in chimpanzee archaeology, e.g. at the Panda Tree site). There are further difficulties of sampling, which will be mentioned below.
Two factors at least offer compensation: one is the sheer quantity of material—many times more than is available for chimpanzee tool-making, so that robust patterns might be picked out; another is the precision of documentation available for some percussive activities, so that sometimes a few minutes of past hominin activity might be recognized that have far wider implications in understanding activities, as in the tools discarded at Boxgrove, UK [90].
Broader comparisons, as treated in this review, create far greater difficulties for rigorousness. Straight away they involve the recording systems of different workers, stretching across many years. For the Acheulean in Africa, typological systems that were more or less agreed developed informally across the first half of the twentieth century, and then were effectively formalized by Leakey, and by Kleindienst and colleagues [12,91]. The schemes were typological, i.e. based largely on appearance or morphology. But at least they did bring together a great deal of material into a common framework. Subsequently, from the 1980s onward, researchers developed far more technological schemes, on the very good principle that such issues as availability of raw material and the techniques of manufacture had large effects on the eventual outputs. de la Torre & Mora [46] summarize this point effectively: that unless you know the technological context, there is little validity in presenting a typological analysis. At the simplest level, where raw material is scarce or occurs in small pieces, stone tools will be worked down further. An archaeologist would need to avoid the danger of interpreting this necessity as choice: technical constraints may well affect the size and appearance of the final toolkit.
Although this technological corrective has been immensely valuable, it must also be said that the lack of a new standard has greatly reduced the comparability of new material (even if the old comparability was debatable). Of the 66 assemblages considered in these comparisons, the great majority were excavated before 1980. The resurgence of Acheulean studies has been focused largely on the bifaces themselves, which can be characterized more easily.
There are further caveats. The first analysis given here attempted to redress the prevalent bias that focuses most attention on bifaces, rather than whole assemblages. Hence the analysis was based on percentages of elements in assemblages. In some cases, these came from very small collections so that, as Roe expressed it, our position is sometimes ‘ridiculous' [45]. If an assemblage is made up from 40 tools excavated across 15 m2, then it is obvious that doubling the area of excavation might well significantly alter percentages. Taphonomic disturbance might also play a part in distorting the record, but its very repetitiveness suggests that this is not a major factor. It is possible, however, that some environments possibly exploited by hominins, such as high slopes, very rarely enter the record at all. Another difficulty is that the tool-makers themselves clearly invested most of their ‘rule-determined’ behaviour into bifaces. There is far less obvious form in ‘tools' such as polyhedrons. Only very detailed studies can discriminate between an artefact that is just a core; a core that was intended to be used as a tool; and a manuport used for throwing or battering (‘manuport’ was a term introduced by Mary Leakey for unmodified stone items brought into a site by hominins [12]).
In many ways, these negatives are outweighed by positives. The very repetitiousness of the early artefacts tells us a great deal about early cultural behaviour. If a pattern emerges robustly from 1 Myr of activity, it must be treated seriously. Of course, it is important that it should not be a construct of the analysis. But at the most basic level, there is little risk that workers were confusing handaxes with choppers or polyhedra with flakes.
The stone artefacts appear to represent an irreducible skeleton of cultural activity, of basic activities that could be carried out best with stone. Very rarely, wood or other material confirms that we may be seeing just the tip of the iceberg of past activities [54,92]. This additional element would of course be very important in making comparisons with primate artefacts [93,94]. The recurrent ‘variable sameness' of the Acheulean suggests that the same basic subsistence activities were being cycled through repeatedly across many hundreds of thousands of years, with adequate solutions that hardly ever pointed to better ones. There was time for every permutation to occur numerous times, and an indication that drift of practice was very seldom favoured beyond very strict limits. The essential lesson that emerges from this study is that Acheulean variability is confirmed to have very deep-seated regularities. The variability within site complexes is somewhat smaller than that in the whole domain of Acheulean variability, but not very much.
Some of the questions originally posed can be answered. There is certainly contemporaneous cultural variation, in broad terms: as similar variation occurs within site complexes, and between them, it is unlikely that this would be absent on the micro-scale. Large quantities of tools are evident, and the regular occurrence of different forms argues for toolsets.
How does the pattern relate to modern primate behaviour, where the chimpanzees provide much the fullest documentation? The chimpanzee behaviour has been known only since the 1960s, so there is an unanswered question of whether this is a recent phenomenon or a longstanding one. There is, however, clear contemporaneous cultural variability: for example, a definite absence in some areas of practices such as nut-cracking that take place in others. The Acheulean probably also shows such variability: sometimes cleavers (axe-edge bifaces) are present, sometimes they are not; sometimes within the greater Acheulean domain, bifaces appear to be totally absent. Even so, the assemblage analysis undertaken here does emphasize recurrence: out of the 12 categories of major artefact (handaxe, core scraper, etc.), more than half of the 66 assemblages have no more than three missing, and 74% have no more than four missing. There is also an important size signal that is probably biomechanical, with an average weight of around 0.5 kg recurring many times for bifaces and other large tools.
Comparisons with chimpanzee cultural variation reveal a different picture. For a start, many or most of the cultural traits considered by Whiten et al. [3,4] do not lead to the manufacture of any artefact at all. Then, only around seven traits appear on all sites. A study of a matrix of 39 most common traits indicates that usually no more than around half are found at a given site [4]. It is tempting from these figures to argue that early hominins had ‘stronger’ traditions, perhaps reinforced by more specific cultural transmission, possibly aided by language. Yet well-defined functional needs and lack of alternatives may also have helped to maintain stability: Lycett and co-workers [95,96] have recently reviewed and explored the factors that may inter-operate, including the effects of different raw materials.
Beyond the assemblage level, very limited data exist in print for measurements of individual chimpanzee artefacts. It has been shown previously that standardization levels can approach or overlap with those in human artefacts [89]. In the latter, level of standardization can vary even from part to part of the artefact, according to perceived importance and specific functional needs.
In the Acheulean, it seems likely that recurring functional needs were responsible for such a very long duration of cultural tradition, but it is also evident that there was long-term change through the Acheulean, and that there were also alternatives to the classic Acheulean (i.e. viable toolkits without handaxes). The long-term change is generally believed to involve the gradual incorporation of new technical ideas such as the Levallois techniques of stone working [97–99].
In terms of percussion, past studies have failed above all in confining themselves to the evident flaked toolkit, rather than extending to the components of hammers, anvils and manuports. It was not possible to approach these systematically from the sources of this dataset. Hence the great value of current studies that concentrate on the documentation of individual cases of use of these categories [62,100,101]. Without doubt, different biases operate when we look at chimpanzee and early hominin artefact sets. A common point is the selection of a ‘blank’ and the application of a reductive technology—although in the case of chimpanzee tools, the blanks are sticks or stems. The circumstantial bias is that we have been far more inclined to look at the task in the case of chimpanzee activities, and the tool in the case of early hominin artefacts.
8. Conclusion
Studies of primate cultural behaviour have revived a more general interest in cultural variability, traditionally the domain of anthropology and archaeology. Percussion is a vital point of contact between the animal and human contexts, although it occurs in very different forms: perhaps 95% used by primates for yielding immediate resources, and perhaps more than 50% by humans for producing tools for future use. Until now, most studies of percussion in archaeology have concentrated on tool production and toolkits, rather than on those activities aimed at yielding immediate resources, with rare exceptions [62]. It is notable that across the many Acheulean assemblages considered here, published information about hammerstones and anvils of all kinds is far more restricted than the information about flaked artefacts. These points underline an issue for archaeology, that its huge numbers of measurements, assembled in weighty volumes, are often not usable in comparisons. This review has brought out some of the difficulties. For example, means and standard deviations provide far less information about an artefact category than full distributions, and both are scarcely useful unless other researchers have the information necessary for characterizing the same category by the same criteria. Some of these points also apply to primatology: published descriptions of artefacts rarely provide full information.
Comparison is however an essential goal, making it worthwhile to emphasize points where practice could be improved. My suggestions would be that where attribute analyses are used, the measurements should be published for all cases, so that full distributions can be plotted; and that advances in analysis should aim to retain continuity, so that the usefulness of older data is kept. Overall, a vastly clearer picture of the past record of percussive activities has emerged since Mary Leakey published the first major monograph on early Pleistocene archaeology less than half a century ago.
The current position does allow positive conclusions to be drawn. Whether seen in the long term, or in the short term of some site settings, the Acheulean shows a constancy that is not there in the chimpanzee cultural traits. One reason for this appearance may be that only tools survive from the deep past—the other transient behaviours are lost—and it seems likely that chimpanzee tools, considered on their own, and apart from other cultural traits, may share more of the patterns found in the hominin record.
Competing interests
I declare I have no competing interests.
Funding
This study was partly supported via the British Academy Partnership and Mobility Scheme, award number PM120165.
Acknowledgements
The author owes special thanks to Acheulean scholars now departed: Pierre Biberson, J. D. Clark, Glynn Isaac and Mary Leakey; to colleagues at Kilombe, especially S. Rucina, A. I. R. Herries, J. Brink and S. Hoare; to J. Brink in respect of finds from Cornelia; R. H. Crompton and D. Curnoe; and to Ignacio de la Torre for the invitation to the Leverhulme meeting, and for collaboration in the Spanish Plateau project; to National Museums of Kenya and the National Council of Science and Technology, Kenya and to the British Academy for support.
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