Showing posts with label Acheulean. Show all posts
Showing posts with label Acheulean. Show all posts

Sunday, 6 April 2025

Million-and-a-half-year-old bone tools from Olduvai Gorge, Tanzania.

Hominins have been using stone tools to access meat from Animal carcases for at least 2.6 million years, and this use of stone tools is also presumed to have helped them switch to a significantly more carnivorous diet. Logically, a Hominin which can use stone tools to hunt large Animals should also be able to make tools from the bones of those Animals, but bone tools have a much more limited record than their stone counterparts.

A number of bone-objects from archaeological sites in Africa dated to between 2.5 and 0.8 million years ago have been interpreted as having been modified by use as tools, for such purposes as digging or Termite fishing, but do not appear to have been deliberately shaped prior to use. A few purpose modified tools have been repoted from Olduvai Gorge in Tanzania, but these were surface finds, lacking the context from which they could be dated. Bone tools are also known from the Konso site in Ethiopia, including a bone handaxe which has been dated to 1.4 million years ago. Bone tools start to appear across Eurasia around 500 000 years ago, and highly shaped bone tools, such as spear and arrow points, barbed points, awls and needles, appear in Africa about 90 000 years ago, spreading to Eurasia around 45 000 years ago.

In a paper published in the journal Nature on 5 March 2025, Ignacio de la Torre of the Instituto de Historia of the CSIC-Spanish National Research CouncilLuc Doyon of the Université de BordeauxAlfonso Benito-Calvo of the Centro Nacional de Investigación sobre la Evolución HumanaRafael Mora of the Facultat de Lletres at the Universitat Autonoma de Barcelona, Ipyana Mwakyoma, also of the Instituto de Historia of the CSIC-Spanish National Research Council, Jackson Njau of the Department of Earth and Atmospheric Sciences at Indiana University, and the Stone Age InstituteRenata Peters of the Institute of Archaeology at University College London, Angeliki Theodoropoulou, again of the Instituto de Historia of the CSIC-Spanish National Research Council, and Francesco d’Errico, also of the Université de Bordeaux, and of the SFF Center for Early Sapiens Behaviour at the University of Bergen, describe an assemblage of bone tools from a horizon at Olduvai Gorge Bed II, which has been dated to 1.5 million years ago.

The tools form part of an assemblage identified as the T69 complex, were derived from a layer between Middle and Upper Bed II, in the Frida Leakey Korongo West Gully at Olduvai Gorge, which has been  radiometrically dated to 1.5 million years ago. T69 complex materials have been derived from six tranches, the bulk of the material comprising early Acheulean stone tools. A total of 10 900 stone tools larger than 2 cm, and over 41 000 smaller artefacts have been recovered, mostly made from a local quartzite.

Geographic and stratigraphic context of the FLK T69 Complex site. (a) Location of Olduvai Gorge in Tanzania. (b) Main geographical features of the Olduvai Basin. The geographical image was adapted from the NASA /USGS ASTER Global Digital Elevation Model. (c) Position of the T69 Complex in the Main Gorge at Olduvai. (d) Stratigraphic position of the bone tool level shown on a composite section of the deepest part of trench T69 and the central area of the T69-T79 west section. (e) Position of the T69 Complex within the general chrono-stratigraphic sequence of Bed II in the Frida Leakey Korongo West Gully area. (f) Normal (left) and polarized (right) thin section photographs of the sandstone containing the bone tool horizon. De la Torre et al. (2025).

In addition to the tools, the assemblage contains abundant Vertebrate fossils, including 9419 identified bone fragments and 13 413 unidentified fragments. Many of the identifiable remains can be attributed to Fish, Crocodiles, and Hippopotamuses, suggesting that 1.5 million years ago, the site was close to water. The majority of the large Animals are Bovids and Hippopotamuses, with some relatively intact Hippopotamus carcasses present. Other large Animals present include Equids, Suids (Pigs), Rhinoceros, and Elephants. Hippopotamus bones are the most abundant, and many of these show signs of deliberate modification.

The faunal elements of the T69 assemblage, including bone tools, are excellently preserved, something not common at Middle Pleistocene sites, allowing for careful documentation and analysis of the material present. De la Torre et al. identify 27 artefacts as unequivocal stone tools, ruling out other forms of damage such as Carnivores gnawing, Crocodiles biting, trampling and fracturing to access marrow; in fact, Carnivore bones are very rare in the T69 assemblage, and the only signs of bone-modification by Carnivores are two possible tooth marks.

Tools are identified as bones with multiple fragments removed, which lack the striations associated with trampling. Experimental breaking of large Mammal bones to recover marrow failed to produce similar flaking. Patterns of breakage consistent with marrow-extraction are present on many bones present in the faunal assemblage, suggesting that this was something done by the Hominins here. This seldom results in more than two or three flakes being removed, whereas the 'tools' have an average of 12.9 flaking scars, typically arranged contiguously and preferentially on their lateral edges.

Twenty seven bone tools were recovered during excavations at Frida Leakey Korongo West Gully, eighteen of which are attributed to Mammals weighing more than two tonnes. Sixteen of these are identifiable, including eight tools made from Elephant bones, six tools are made from the bones of Hippopotamus, and two from the bones of large Bovids. Thus, in an assemblage dominated by Bovid bones, where 169 taxa are recorded and Elephant remains make up about 1.1% ot the total, more than half the tools are made from Elephant bones. One of the tools is made from the proximal portion of the radius of a large Bovid, all the others from long portion of limb bones, predominantly the femora, tibiae and humeri.

Tools made on long bone diaphysis of very large Mammals. (a) Indeterminable taxon larger than two tonnes (accession number T69L20-3009). (b) Elephant (accession number T79L10-2511). Scale bars are 5 cm. De la Torre et al.  (2025).

The Frida Leakey Korongo West Gully tools represent a set of technological and behavioural innovations previously unrecorded in Hominins of this antiquity. The tools are relatively 'fresh', which is to say they were apparently buried quite soon after being made, and do not show signs of having sat on the surface and subject to weathering. The Hippopotumus bone tools all appear to have been made from fresh bone (i.e. from Animals which had died shortly before the tools were made), but some of the Elephant bone tools appear to have been made from bones partially weathered before flaking occurred, suggesting that old Elephant bones were recognised as a valuable resource and collected separatley from scavenging carcases for food. Elephant bone tools range from 22 to 38 cm in length and from 8 to 15 cm in width, making them the largest in the assemblage. Hippopotamus bone tools are slightly smaller, 18 to 30 cm in length and 6 to 8 cm in width.

Elephant bone tools also show more working, showing on average 17.3 flake removal scars, compared to an average of 13.3 scars on Hippopotamus bone tools. Among the fifteen tools made from unidentified Animals, seven are comparable to Elephant or Hippopotamus bone tools in size, with similar numbers of scars, while eight are smaller, with an average of six flaking scars. The preferred method of tool making appears to have been to first remove large flakes to give the tools its shape, then remove smaller flakes to regularize the edge surfaces. Experimentally braking bones for marrow-extraction produced scars significantly shorter than the initial flaking used in tool production at Frida Leakey Korongo West Gully, indicating deliberate intent from the outset. The shape of the scars is compatible with the use of hand-held hammerstones, although these would have needed to be large and heavy.

Six of the large-Mammal bone tools show a recurrent shape, with one crescent-shaped end and one pointed end, combined with a large notch on the middle part of the tool. This was achieved using an average of 16.8 flake removals, the majority of which are associated with the creation of the notch. The pointed end of the tool corresponds to the robust part of the diaphysis (middle section) of the bone, which the rounded end appears to be derived from the metaphysis (wider, end-part) of the bone. 

Large bone tools made on diaphysis fragments. (a) Elephant humerus (accession number T79L10-9047). (b) Hippopotamus femur (accession number T79L10-18461). Scale bars are 5 cm. De la Torre et al. (2025).

The bone tools at Frida Leakey Korongo West Gully are larger, heavier, more elongated, and more worked than stone tools from the same site, suggesting that bone was deliberately chosen as the material of choice for such tools. The tool makers appear to have a good understanding of the properties bone as a material, and the anatomy of the Animals from which it was derived, preferentially choosing Elephant bone even when this was not fresh, and consistently making tools to the same plan, following a standard flaking pattern.

Recurrent distal fracture patterns on additional bone tools. (1) Tibia diaphysis of cf. Hippopotamus (accession number T69L20-1872; dimensions 222 × 80 × 54 mm). (2) Accession number T69L20-3633. (3) Accession number T77L64-823. (4) Elephant long bone diaphysis (accession number T78L84-75; dimensions 353 × 103 × 53 mm). Each scale bar segment is 1 cm. De la Torre et al. (2025).

The T69 technology from Frida Leakey Korongo West Gully represents evidence for bone tool production by Hominins 1.5 million years ago. Previously, our knowledge of bone tool use in the Early Stone Age consisted of bone fragments which had apparently been used as tools without modification, and isolated tools with possible evidence of working and/or dubious stratigraphy (dating), with the regular appearance of deliberately made bifacial bone tools not occurring till after 500 000 years ago. 

The Frida Leakey Korongo West Gully discovery shows that Hominins had a complex tool industry which included the production of large knapped bones a million years before bifaced bone tools become common. These tools date to a key period in technological innovation, during which the early Acheulean technology was replacing the late Oldowan technology, a change which probably reflects a general increase in behavioural complexity. This increased behavioural complexity appears to have included a greater ability to select materials, a better ability to imagine the shape of a finished tool and work towards it, and morse sophisticated knapping techniques to reach that end. At this point bifacial tools were starting to appear, forming a minor part of tool assemblages and not reaching the large sizes seen in later Acheulean assemblages. 

Hominins at this stage are known to have been scavenging the carcasses of large Mammals and actively developing butchery techniques, which would have made bone a readily available material. It is possible the large bone tools from the Frida Leakey Korongo West Gully fulfilled the same role as the large bifacial tools of later Acheulean assemblages, and that the development of these more advanced stone tools led to the abandonment of large bone tools. In this scenario, the bifacial bone tools of the Middle Pleistocene might represent a reversion to bone use among populations lacking access to good lithic material.

An alternative hypothesis is that bone technologies appeared and disappeared several times over the course of the Pleistocene, all being being slightly more common in the Early Stone Age than previously realised. Either way, Early Pleistocene use of bone tools is clearly an under-reported phenomenon, possibly due to collection bias (archaeologists finding stone tools, because that is what they are looking for). Further research may reveal earlier use of bone tools, as well as a more widespread use of bone as a tool making material in the Early and Middle Pleistocene.

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Wednesday, 17 April 2024

Earlier and Middle Stone Age tools from Egypt's Eastern Desert.

During the Pleistocene interglacial phases, Hominin and Human groups migrated out of Africa and into Asia through Egypt. For a long while it was presumed that the main route of migration was along the Nile, but in recent years it has become increasingly apparent that the Eastern Desert was also a significant migration route, although little is known about the populations that inhabited this region.

In a paper published in the journal AntiquityAlice Leplongeon of the Center for Archaeological Research of Landscapes at KU Leuven, the Department of Anthropology at the University of Connecticut, and Histoire Naturelle de l’Homme Préhistorique and the Muséum National d’Histoire Naturelle at the Université de Perpignan Via DomitiaMaxence Bailly of the Maison méditerranéenne des sciences de l’homme at Aix Marseille Université, and Gwenola Graff of the Département Homme et Environnement at the Muséum national d’Histoire naturelle, report on a series of new Earlier Stone Age and Middle Stone Age finds in the Wadi Abu Subeira area of the Eastern Desert.

During 2022, Leplongeon et al. mapped 22 new sites, including single artefact sites, sites with scatters of stone tools, and workshops where stone was worked.  All were found either on plateaux tops or plateaux slopes, never in the wadis that separate the plateaux The isolated tools included a large symmetrical handaxe and a cleaver made from coarse ferruginous sandstone. Scatters of artefacts appear to have no pattern to them; the largest being over 500 m long, with an artefact density of between 0 and 10 artefacts per square meter. Tools were made from a variety of rock types, including quartz, silicified wood, silicified sandstone and chert. Of these, only quartz was available in the immediate area, although the other materials could often be found in wadi bottoms or on nearby plateaux. The items were a mixture of Earlier Stone Age tools, such as large axes, and Middle Stone Age tools, such as Levallois cores, probably representing an accumulation of items which had built up over a long period of time, and reflecting several distinct phases of occupation at the same sites, as well as, in places, accumulations of items caused by erosion.

Earlier Stone Age isolated finds: (A) & (B) context and photograph of cleaver L652; (C) & (D) handaxe L672. Leplongeon et al. (2024).

Leplongeon et al. identified five workshops where stone tools were manufactured, each comprising an accumulation of lithic artefacts next to a ferruginous sandstone, although the nature of this sandstone otherwise varied considerably. The highest density of artifacts was found at a workshop on a site referred to as the 'Leaf Plateaux', where there were more than 50 artefacts per meter squared, adjacent to outcrops of fine-grained red and yellow ferruginous sandstone. Blocks of material had apparently been broken from the outcrops, then reduced using a variety of knapping techniques. These include several Levallois cores, as well as blade cores and a few retouched tools including two bifacial points, indicating that this site is of Middle Stone Age origin. 

Middle Stone Age lithic workshop (L618-623). Overview (A) and detail (B) of an area of the workshop; (C) extraction face; (D) Levallois core; (E) bifacial point. Leplongeon et al. (2024).

About 800 m to the east of this Middle Stone Age workshop, an outcrop of a coarser type of ferruginous sandstone, another workshop yielded several large centripetally flaked cores and several handaxes and preforms. All of the artefacts here had a dark desert varnish (indicating age), and appeared attributable to an Acheulean technology. Acheulean sites are rare in northeast Africa, making this a significant discovery.

Earlier Stone Age lithic workshop (L602–603). (A) overview of the site with the two main concentrations of artefacts; (B) detail of area 2; (C) large centripetal core; (D) handaxe preform. Leplongeon et al. (2024).

The presence of two workshops from very different periods shows repeated utilisation of outcrops in the area by different waves of inhabitants, but also that these different peoples with different technologies selected slightly different types of stone as most ideal for their purposes. Notably, workshops and artefact clusters appear to be particularly connected to outcrops of the Nubia Sandstone and in particular the Timsah Formation, suggesting that ancient inhabitants of the Wadi Abu Subeira were capable of following a particular geological formation, apparently for the workable qualities of this material.

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Saturday, 16 March 2024

Understanding the giant handaxes of the British Lower Palaeolithic.

The Lower Palaeolithic is the earliest stage in the archaeological record from which stone tools are known, and while such ancient tools are rare, they are much more common than the remains of the Hominins which produced them, or any other remains of their activity, thus providing a key insight into the activities of our ancient ancestors. The first bifacial handaxes appear in the African archaeological record about 1.76 million years ago, and are considered to be a significant conceptual leap from the Oldowan core-and-flake technology which preceded them, although whether these axes had an entirely novel function or were a new technological approach to tasks which were already undertaken is unclear. One of the notable manifestations of this technology was the manufacture of 'giant' handaxes, notably larger than other examples of these tools, sufficiently large that archaeologists are divided as to whether they had any practical function at all.

It has been suggested that the purpose of these giant axes may have been social rather than practical, with the production of such tools representing a significant time investment, and therefore being an indicator of patience and commitment to a project. Giant, highly symmetrical handaxes from British sites such as Furze Platt and Shrub Hill have been used to support this hypothesis. An alternative suggestion is that the Hominins involved may have found the manufacture of such giant axes an aesthetically pleasing activity in its own righty, an early sign of artistic expression emerging from the purely functional.

In a paper published in the journal Antiquity on 4 March 2024, Luke Dale of the Department of Archaeology at Durham UniversityAaron Rawlinson, also of the Department of Archaeology at Durham University, and of the Department of Britain, Europe and Prehistory at the British MuseumPete Knowles and Frederick Foulds, again of the Department of Archaeology at Durham University, Nick Ashton, also of the Department of Britain, Europe and Prehistory at the British Museum, David Bridgland of the Department of Geography at Durham University, and Mark White, once again of the Department of Archaeology at Durham University, present the results of a study of giant handaxes from across the British Lower Palaeolithic.

Dale et al. note that symmetry is often cited as a key feature of giant handaxes, but that no previous study appears to have actually looked at whether these axes are actually more symmetrical than other axes from the same period, nor whether the style or frequency of these objects varies over time. 

All giant handaxes are associated with the Acheulean technology, which in Britain was present by Marine Isotope Stage 13, about 500 000 years ago, and may have appeared as early as Marine Isotope Stage 15, about 600 000 years ago, if recent dates for the Fordwich and the Bytham River terraces are correct. The global climate underwent a series of oscilations during the Middle Pleistocene (781 000-126 000 years ago), which in Britain manifested as a series of warm interglacials during which Hominins invaded and settled the landscape, interspersed with colder glacial intervals during which they disappeared. This pattern results in a series of distinct cultural intervals within the British Acheulean, providing a potential opportunity to detect discrete phases in the manufacture of giant handaxes in Britain.

Dale et al. obtained data on 4160 handaxes of all sizes, from 47 sited dating to between Marine Isotope Stage 15 and Marine Isotope Stage 9. For convenience, each (odd) Marine Isotope Stages was considered to represent a warm phase, as well as the cool phases bracketing it, thus Marine Isotope Stage 11 in fact refers to the Marine Isotope Stage 10-11-12 cool-warm-cool cycle; each cycle therefore represents about 100 000 years. The warm phases covered by Dale et al.'s study are MIS 15 (approximately 610 000 to 560 000 years ago), MIS 13 (approximately 524 000-474 000 years ago), MIS 11 (approximately 427 000 to 364 000 years ago), MIS 9 (approximately 328 000-301 000 years ago. Many of the sites in the study are well dated, but others represent chronologically mixed assemblages, such as Dunbridge in Hampshire, where the artefacts were recovered from dredged aggregates, have only been tentatively dated, such as Whitlingham in Norfolk, or are known to have been the subject of collecting biases, such as Furze Platt in Berkshire. Dale et al. recognise that these factors will have an impact on the reliability of their study, but reason that the size of their dataset should offset this. They also note that a further two giant handaxes were discovered at Frindsbury in Kent after the initial daft of their study was submitted, and that these are thought to date to MIS 9.

Handaxes were divided into six classes on the basis of their symmetry, with Class 1 representing near perfect symetry, and Class 6 indicating almost no symmetry.

Dale et al. measured the length of all the 4160 handaxes in their study, splitting them into four categories; small (less than 80 mm in length), average (80-150 mm in length), large (150-220 mm in length) and giant (more than 220 mm in length.

Forty two of the handaxes fell into the 'giant' category, of which 33 can be confidently assigned to the MIS 9 cycle, the final stage of the Acheulian in Britain. A single giant axe was dated to MIS 11, and two to MIS 13 - although one of these is- derived from a MIS 6 gravel bed, and is interpreted as having been reworked from a MIS 13 deposit. Since MIS 9 only represents about 1% of the British Pleistocene record, this concentration of giant handaxes in MIS 9 deposits is interpreted as being significant.

In the 1960s archaeologist Derek Roe developed a system of classifying handaxes upon their shape. The majority of giant handaxes in Dale et al.'s study conform to Roe's Group I (pointed, with cleavers) and Group III (plano-convex), both of which are associated with MIS 9. Notably, handaxes in an assemblage from Broom on the Devon/Dorset border, which included several giant handaxes, while still from MIS 9, did not easily fit into Roe's scheme. The stone tools here were made from chert derived from the Upper Greensand, and tended to be ovate or asymmetrical, unlike other MIS 9 assemblages.

Other than the presence of giant handaxes in the MIS 9 material, the size distribution of handaxes between different interglacials varied little, with the average size of the axes varying only by 10-20%, although the MIS 15 handaxes appear on average slightly larger than those from later assemblages, and the MIS 11 assemblage contained a higher proportion of small handaxes than other stages. However, Dale et al. note that their MIS 15 material came from only two sites, Brandon Fields in Suffolk and Fordwich in Kent, with the material used at Fordwich being elongated pipeflint, which lends itself to the making of larger bifaced tools with a minimal amount of effort. Given this, Dale et al. are reluctant to read much into this data without further MIS 15 material becoming available.

Analysis also suggests that axes from MIS 13 and MIS 9 are on average larger than those from MIS 11, and MIS 9 axes are also slightly larger, on average, than those from MIS 13. Dale et al. are uncertain whether this variation relates to cultural differences between the different populations colonising Britain in each interglacial, and make no further assessment of this data at this time.

A comparison of handaxe length between MIS 15, 13, 11 and 9, with handaxes grouped according to length class. MIS 15 displays a greater proportion of handaxes in the large class, while small handaxes are much more limited. MIS 11 displays a greater proportion of small handaxes. Giant handaxes represent a very small percentage of the total assemblage, emphasising their status as extreme outliers beyond the usual variation in handaxe length. Frederick Foulds & Mark White in Dale et al. (2024).

The majority of giant handaxes come from the Thames Valley or its southern tributaries, although examples are also known from Norfolk Yare, the Axe Valley and Solent River deposits. The majority of sites where they are found are close to primary chalk-flint outcrops, where large flint nodules were available. However, some were found in flint-poor areas, such as Wolvercote and Stanton Harcourt in Oxfordshire, whereas older archaeological sites, such as Boxgrove in West Sussex, and Elveden in Suffolk, are located near excellent sources of large flint nodules, but yield no giant handaxes. 

No giant handaxes available from Stoke Newington in London, one of the UK's best MIS 9 sites, although it is known that the site did yield such axes; as the original excavator of the site, Victorian archaeologist Worthington Smith, illustrated several giant handaxes in his book, Man, the primeval savage, but then gave these away to distinguished visitors to the site; these axes are thought to be either in private collections or lost. 

Geological map displaying the locations of sites with giant handaxes in relation to underlying bedrock geology, coloured as per the British Geological Society scheme. Colours for chalk bedrock are highlighted in the legend. Note that large clasts in overlying superficial deposits largely reflect local geology and ‘exotic’ raw materials would generally be smaller in size. Dale et al. (2024).

Of the forty two giant handaxes in the study, thirty five (or 83%) are pointed, typically conforming to the lanceolate (lance-shaped) or ficron (having a pointed planform shape with biconcave edges) type. These shapes are considered to be part of the same typological grouping as chisel-ended cleavers, a grouping which is thought by many archaeologists to be restricted to MIS 9. Although ficrons are associated with giant axes, not all ficron handaxes are giant; known ficrons range in size from 63 mm to 307 mm.

Examples of giant pointed and ficron handaxes: (A) the ‘Beast of Biddenham’ (length 253 mm); (B) a giant ficron from Canterbury West (length 285mm) (photographs courtesy of the British Museum (A) and The Seaside Museum, Herne Bay (B)). Dale et al. (2024).

Since the overwhelming majority of the giant axes date from MIS 9, Dale et al. examined axes from this stage for their symmetry. Handaxes from this interval were found to vary a great deal in their degree of symmetry, although there was a direct corelation between axe length and symetry, with longer axes tending to be more symmetrical than shorter ones. 

Splitting the axes into groups based upon their size emphasised this trend, with axes in larger categories being more symmetrical than those in smaller size categories. Examination of earlier axes suggested that this tendency for larger axes to be more symmetrical was also present in MIS 11, but not MIS 15 or 13, although the number of axes available from the earlier periods makes this result less reliable. 

However, this tendency for larger axes to be more symmetrical in MIS 11 and 9 deposits may be influenced by another trend, which is for axes in general to be much more symmetrical in MIS 13 and 11, compared to other periods, and in particular to MIS 9. Thus, the increased symmetry seen in the large MIS 9 axes is balanced by a decrease in the symmetry seen in smaller axes, with the smallest axes (less thn 100 mm in length) tending to be roughly and quickly made, with very low symmetry. 

Giant handaxes are often cited as a key feature of Hominin cognitive and cultural development. Dale et al.'s study demonstrates that these items became prevalent in Britain during MIS 9, i.e. immediately prior to the Lower-Middle Palaeolithic transition, 300 000 and 250 000 years ago. This interval has already been identified as one of significant technological innovation, beginning with a non-handaxe phase, which was then followed by a period with handaxes, then a final phase in which a hierachical core-working technology, known as the proto-Levallois was introduced. The linking of giant handaxes to this stage adds another element to this increasing cultural complexity.

The presence of giant handaxes is often independent of the availability of suitable manufacturing materials, with giant handaxes known from areas of Oxfordshire where there are no sources of suitable large flints. This implies that either the raw material or the finished axes were transported for at least 25-40 km to the sites where they were found. This phenomenon has also been observed in France, with a giant handaxe found at Caune de l’Arago in Pyrénées-Orientales Department, more than 30 km from any suitable source of material. This transportation of materials is another new innovation from this phase, with most previous Lower Palaeolithic sites using stone sourced less than 5 km from the location where it was discovered. The increased effort being put into moving giant axes to locations away from the materials from which they were made lends further support to the hypothesis that these were valuable items, although another possibility is that these tools had a long working life, and were subject to regular reworking to maintain a sharp edge, which would explain the plano-convex form of many handaxes, including those at Wolvercote in Oxfordshire. Under this hypothesis, many large handaxes would have been discarded prematurely, before being extensively reduced.

Many of the giant handaxes are ficrons, a type of axe otherwise rare in Britain. Large ficrons are particularly striking objects, apparently crafted with care to maintain the length of the axe while reducing the width of the upper and central portions of the axe. This may have been a way to correct for a lack of symmetry in the original platform (the rock from which the ficron was made), or a sign of the tool having an extended lifespan, with regular resharpening. Another hypothesis is that the width reduction may have been a way to reduce the weight of the tool part of a general Acheulian trend for longer tools to be narrower. The alternative is that the ficron-shape was desired from the outset, and that the extra effort put into producing an axe of this shape is an indicator of the significance of the object to the people who made it. Whatever the truth, there does appear to be a link between the high symetry, large size, and unusual shape of these giant ficrons which appears to show a degree of artistry transcending the merely functional.

It has often been speculated that giant handaxes had no practical function, but experimentation has shown that examples far larger than anything found in Britain can be used as tools. Even the largest giant axes can be used two handed, can be used for digging, or can be used as static cutting tools across which materials could be drawn. Despite this possible functionality, all the British giant handaxes are distinctively formed and highly symmetrical, making it hard to believe that aesthetic considerations played no part in their manufacture. 

The oldest known giant axe is 1.6 million years old, and came from the Olduvai FLK West site in Tanzania. This is long before anything else considered to be even possibly an expression of communal artistic standards, and therefore was presumably made by an individual for reasons that were important to them alone. A more communal approach to aesthetics begins to appear about 500 000 years ago, at which point tools also being to appear which have been shaped to make the most of features such as fossils on the rock cortex. Giant handaxes may also represent an aesthetic development, with the size and symmetry of stone tools being increased to create visually pleasing objects. This implies the people who made these tools were capable in taking pleasure in creating such objects, which would imply an increasing level of cognitive and social development.

Giant handaxes may also have had some symbolic purpose. The manufacture and then apparent discarding of objects which take a degree of forward planning and labour investment may have been a way of marking territory, or signposting important locations to other members of the community.

The ability to produce giant handaxes clearly predates MIS 9; they are known from earlier in the Lower Palaeolithic and across the Acheulean world. A 300 mm-long lanceolate giant handaxe from Caune de l’Arago is thought to date from MIS 14, and other examples from across northern France, at sites including St Acheul and Thennes in the Somme Valley, Vaudricourt in Pas-de-Calais, and Montguillain in Oise Department, have variously been dated to MIS 11 and 9, although none of these dates are considered to be particularly secure. Giant handaxes are also known from the Levant and Middle East, though these tend to be less accurately dated. A 220 mm long example from Qesem Cave in Israel is thought to be between 420 000 and 200 000 years old, while a 265 mm-long basalt handaxe was found at Wadi Dabsa in Saudi Arabia. A site at Porto Maior in north-west Spain was occupied for a long interval across MIS 8-7, by a people of apparent African affinities, who regularly produced giant handaxes, picks and cleavers. Giant handaxes have been found at 23 sites across Africa, including Olduvai in Tanzania, where the largest such axe is 330 mm long and 1.4 million years old, Isenya in Kenya, where the largest axe is 253 mm long and 700 000 years old, and Kalambo Falls in Zambia, where the largest axe is 350 mm long and 300 years old. However, the African Acheulian, with which many sites in southern Europe and the Middle East are also associated, has a greater emphasis on large cleavers, picks, and handaxes, together referred to as 'large cutting tools'.

The MIS 9 giant handaxes from Britain appear to show a different phenomenon, a discrete technological interval in which larger, more symmetrical tools suddenly appeared. In France, the MIS 9 sites in the Somme Valley are the closest available to compare, with the Cagny l’Epinette locality producing 33 handaxes, the largest of which is still less than 170 mm in length, while the Revelles site has produced 52 handaxes, none more that 190 mm long. Ferme de l’Epinette, a MIS 10 site in the Somme Valley has produced 31 handaxes, all less than 180 mm long, while the MIS 9 stage of the Soucy complex in the Paris Basin has produced 178 handaxes, the largest of which are 155 mm long, and no handaxe from the entire complex exceeds 180 mm. The Orgnac Cave site in the Ardèche Department has a sequence of archaeological layers running from MIS 10 to MIS 8, but has produced no handaxes more than 200 mm in length. The MIS 9 layers at Menez-Dregan in Brittany have produced 29 handaxes, all less than 160 mm in length, although this may be because the tools are made from sandstone and microgranite beach pebbles which would not lend themselves to making bigger tools. This lack of large rocks for use as a source of tools may also account for the generally small handaxes found at Atapuerca in Spain.

Thus the production of giant handaxes in Britain appears to be a geographically, as well as chronologically, restricted phenomenon. This fits in with a more modern understanding of the Acheulian Culture, which includes many such small-scale variations, rather than being a single long-lived and widespread monoculture, as was once perceived. 

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Saturday, 30 September 2023

Evidence for the construction of wooden structures in the Middle Pleistocene of Zambia.

The first evidence of woodworking is associated with the Early Pleistocene of Oldowan Culture of East Africa, with a number of stone tools showing wear traces and residues left when they were used to work wood. The earliest known wooden tools come from the Middle Pleistocene of Southern Africa, with waterlogged wooden items from several sites, associated with Middle Stone Age and Acheulean stone tools. One such site is at Kalambo Falls in northern Zambia, where a series of wooden artefacts were recovered in the 1950s and 1960s, from horizons which also produced Acheulean tools. These included a wood chip, and three objects with transverse notches interpreted to have been made by intentional shaping of the wood. The Amanzi Springs site in Eastern Cape Province, South Africa, a stick with a possible chop mark was discovered in a waterlogged deposit which also produced Acheulean tools in the 1960s. These deposits were radiometrically dated to between 404 000 and 390 000 years before the present, from unmodified wood within the same strata. A wooden object with cut marks and fine striations from the Florisbad Spring Deposit in Free State, South Africa, was found alongside Middle Stone Age stone tools and remains of the Hominin Homo helmei; this is considered to be the oldest known clearly modified wooden object, but has not been dated beyond Middle Pleistocene.

In a paper published in the journal Nature on 20 September 2023, Larry Barham of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, Geoff Duller of the Department of Geography and Earth Sciences at Aberystwyth University, Ian Candy of the Department of Geography at Royal Holloway, University of London, Christopher Scott, also of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, Caroline Cartwright of the Department of Scientific Research at the British Museum, John Peterson again of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, Ceren Kabukcu, again of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, and of the Interdisciplinary Center for Archaeology and Evolution of Human Behaviour at the University of Algarve, Melisa Chapot, also of the Department of Geography and Earth Sciences at Aberystwyth University, F Melia, again of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, Veerle Rots of the Prehistory TraceoLab  at the University of Liège, Nikki George, again of the Department of Archaeology, Classics & Egyptology at the University of Liverpool, Noora Taipale, also of the Prehistory TraceoLab at the University of Liège, Peter Gethin, once again of the  Department of Archaeology, Classics & Egyptology at the University of Liverpool, and Perrice Nkombwe of the Moto Moto Museum describe recently described evidence for wood being used tob build a structure in the Middle Pleistocene at Kalambo Falls.

New excavations at Kalambo Falls in 2019 recovered five modified wooden artefacts from four different areas, at different layers within the sediments, both above and below the current level of the river. A sixth wooden object showed no signs of intentional modification, but was associated with one of the modified wooden items and some Acheulian stone tools, in a layer below the current river level. One of the other modified wooden objects was also found (separately) associated with Acheulian stone tools, in a layer below the current river level. The remaining modified wooden objects were found without associated stone tools in layers above the current river level, two of them together and one on its own. 

Location of Kalambo Falls archaeological site and excavated areas. (a) Site location in south-central Africa. (b) Course of the Kalambo River (in outline) from around 1956 to 2006 in relation to previous excavations at sites A, B, C, D and C North. Site BLB (2019) and excavation units BLB1, BLB2, BLB3, BLB4 and BLB5 are located along the current main channel (blue). (c) Cross-section of the 2019 excavation units showing the location of 16 luminescence dating samples (KF01–KF17, dark blue circles, uncertainties (±) shown at 1 − σ) by unit. Unit BLB1 is a geological section of the full cliff exposure from ground surface to below water level. The three colour bands indicate clusters of pIR IRSL ages grouped by mean ages and standard error of the mean. The earliest wood objects (BLB5, BLB3) are in the lower green band with a mean age of 476 ± 23 000 years. The blue band has a mean age of 390 ± 25 000 years and incorporates the wood object in BLB2. The overlying yellow band has a mean age of 324 ± 15 000 years and incorporates wood objects in BLB4. Red diamonds indicate modified wood objects. Barham et al. (2023).

At Kalambo Falls a nine-metre-deep exposure of fluvial deposits, interpreted as having been laid down by a laterally migrating river with moderate-to-high energy flows, comprises mostly gravels and course sands, with occasional non-contiguous beds of fine sand, silt, and clay. This deposit has an elevated water table, which has preserved wooden objects and plant matter within the bottom two metres of the sequence. Wooden items are interpreted as either having been deliberately deposited by Hominins or carried to its current location by the flow of the river. 

Modified wood tools from site BLB, Kalambo Falls, 2019. (a) BLB5 structural element (object 1033). (b) BLB3 ‘wedge’ (object 660). (c) BLB2 ‘digging stick’ (object 219). (d) BLB4 cut log. (e) BLB4, tapered piece with single chop-mark. Scale bars are 10 cm. Barham et al. (2023).

Sixteen dates were obtained from this sequence using a combination of optically stimulated luminescence dating of single quartz grains and postinfrared infrared stimulated luminescence dating of potassium-rich feldspars. These dates form a stratigraphic sequence (i.e. the older dates are below the newer dates in the succession), with one exception, and fall into three distinct age clusters. The oldest cluster, centred on 476 000 years ago (and extending approximately 23 000 years in either direction of this date) includes all of the samples from below the current river level, including two modified wooden objects, BLB3, which was found with a piece of unmodified wood and a collection of Acheulian tools, and BLB5, which was found with another group of Acheulian tools. The next cluster, centred on 390 000 years ago and extending 25 000 years on either side of that date, contained a single wooden tool, BLB2, found on its own, above the level of the current river, while the final cluster, centred on 324 000 years ago and extending 15 000 years on either side of that date, includes a pair of wooden artefacts, BLB4, found together.

It was possible to identify the wood from which the artefacts were made, but attempts at carbon dating them produced 'infinite' results, indicating they are more than about 50 000 years old. Infrared spectroscopy of these specimens showed that they had begun to mineralize, with silica beginning to replace the original wood. The tools were interpreted by comparison to later wooden tools from Holocene archaelogical sites in Zambia and the UK, as well as those made by modern Human populations.

The oldest tool, object 1033 from layer BLB5, is a Large-fruited Bushwillow, Combretum zeyheri, log 141.3 cm in length and 25.6 cm in width, which was found overlying another log at an angle of 75°. Importantly, this overlying log has a notch, 13.2 cm long and 11.4 cm wide, intentionally cut into it where it rests on the underlying log, which also shows signs of modification. Bark is still present on both logs, bur is absent around the notch, emphasizing that this was intentionally cut, although this is not in doubt, due to the visible chop and scrape marks on the exposed wood within the notch. 

Structural unit formed by two overlapping logs in BLB5. The underlying log passes through a central notch cut into the upper log (object 1033) and extends into the section. Plan view of the unit (left) and during excavation (right). The numbers refer to the distance in centimetres. Barham et al. (2023).

The notch shows several areas of scrape marks, overlapping in the centre. These are 'v'-shaped in profile, up to 24 mm long and 3.2 mm wide. The end of the log is tapered, and also appears to have been modified.

Annotated images of the BLB5 upper log (object 1033) showing areas of intentional modification. From left to right, the location of the central notch in profile, shaping marks in and on the margins of the notch (a)–(k), the notch in profile from the opposite side. The image on the right shows the upper surface of the log, and the three parts of the log (1)–(3) separated by cracks. White arrows indicate locations of shaping facets on the sides and upper surface of the log. Barham et al. (2023).

The underlying log also shows signs of modification, with a series of small striations running across the grain of the wood at its mid-point, again with 'v'-shaped profiles indicative of scraping, and the end of the log which passes through the notch in the upper log showing signs of having been intentionally thinned by the scrapping of a series of notches along the grain of the wood.

Shaping marks on the upper surfaces of object 1033 and on the underlying treetrunk. Clockwise, from left upper left; chop marks on Part 2; cluster of small convex hewing marks on Part 1, near Part 2; cutmark (upper arrow) and small facets (lower arrows) on Part 1 near Part 3; intercutting chop marks on the upper right edge of the Part 3 taper; underlying log midsection, intersecting cutmarks transverse to the grain (bold arrow, upper left, indicating direction of grain). Marks on underlying treetrunk interpreted as result of scraping, perhaps from debarking. Barham et al. (2023).

Infrared spectroscopy suggests that the notch has also been modified by fire-shaping, something which was reported on another log of similar size (165 cm) previously found with Acheulian artefacts at Kalambo Falls, but not dated, which also had a wide, deep groove cut into it and tapering ends. This wood was presumed to have been part of a structure, and thought to have been modified by the actions of Early Humans. The new discovery of two logs interlocking on a similar notch, strongly supports the idea that the function was constructional in purpose, although the age of the strata from which the wood was recovered considerably pre-dates the oldest estimates for the emergence of Modern Humans.

Shaping marks on the treetrunk underlying object 1033 notch, BLB5. Surface modifications on the treetrunk beneath and just beyond the notch. Images described counter clockwise: white arrows highlight direction of striations, some V-shaped in profile, cutting across the grain from the edge toward the middle of the surface; a set of parallel transverse striations/cutmarks, with V-shaped profiles (white arrows) along ridge descending to a flat tapered surface; inset detail of the striations on the ridge crest; overview of the set of striations along the ridge; profile view of the flattened surface below the ridge; profile view of the ridge and break of slope onto the flat tapering surface which extends beyond the notch; plan view of the flat tapering end with transverse striations and cutmarks with V-shaped profiles (white arrows) interpreted as shaping marks. Barham et al. (2023).

The second collection of material below the modern river level, BLB3, comprises another collection of Acheulian tools, including flake tools, cleavers, handaxes and core axes, as well as two wooden objects, a 'v'-shaped piece of Figwwod, Ficcus sp., showing no signs of intentional modification, and a flattened branch of Sausage Tree, Kigelia africana, 36.2 cm in length and with one end carved to a point.

Shaping and possible use marks on object 660, BLB3. Surface modifications on ‘wedge’ shown clockwise: white arrows indicating location of modifications on base and either side of the tip; basal crack (top arrow) and side split, facet ‘a’ intercepts a striation, possible use damage, and ‘b’ indicates a set of faint transverse striations; ‘c’ and ‘d’ intersecting facets above tip, ‘e’ and ‘f’ are sets of parallel faint transvers striations; tip face with convex step terminations, possibly from use. Barham et al. (2023).

Barham et al. believe that this artefact has been intentionally shaped by repeated high-impact blows, in order to form a wedge. Similar wedges have been recovered from the Mesolithic Starr Car site in the UK, and are known to have been used for a variety of purposes by Aboriginal Australians, but nothing similar has ever been discovered in a Middle Pleistocene deposit.

The BLB2 horizon, dated to about 390 000 years ago produced a single wooden item, broken into two pieces which fitted together; one of these was found still embedded in the sediment, the other in the river directly below, where it had apparently fallen. The combined wooded object is about 62.4 cm in length, made of African Sausagewood, stripped of all bark and intentionally fashioned into a point, being 11.9 cm wide at the base, 6.1 cm wide in the middle, and 1.3 cm wide at the tip. The object has striations cutting across the grain of the wood in several places, these being less than 10 mm wide and convex in profile. The tip of the object is slightly rounded, which might be a sign of wear from use. or derive from its time in the river. The object is interpreted as a digging stick similar to those used historically by foragers in the Kalahari. Similar artefacts are known from the Middle Holocene of Zambia, but again the Middle Pleistocene occurrence is unprecedented. 

Shaping marks on object 219, BLB2. Upper image shows all views of the object with white arrows indicating location of marks on either side of the tip and above the tip. Both sides of the tip (two images on left) have a faint set of transverse striations and two or more small facets away from the tip. (Scale bar is 1 cm.) The vertical image to the right shows four groups of faint parallel transverse striations in an area with two knots, no scale. The object is interpreted as a digging-stick. Barham et al. (2023).

The BLB4 horizon, dated to about 324 000 years ago, produced two wooden artefacts and no stone items. The uppermost of these is a rectangular piece of Large-fruited Bushwillow wood measuring 59.24 cm by 29.34 cm by 7.7 cm, with traces of bark and sapwood still present. This shows signs of having been flattened, but this may have been due to the weight of the sediment above it. It also has a large chop mark running across its obverse surface. Barham et al. interpret this item as a piece of tree trunk which has been intentionally cut to size, indicating a capacity to process large pieces of wood.

Chop marks on ‘cut log’, BLB4. Upper image shows all views of the object and location of modifications (white arrows) on the ends, ‘a’ and ‘b’, two marks on the underlying surface and the preservation of bark on both surfaces. Image below is ‘a’ with its distinctive stepped chop marks (black arrows), and underlying grey image (denatured RTI) shows the width of the step between the first and second chop-mark expanding, left to right, from 13 to 25 mm. The deep, slightly convex cut of the first chop is visible. The underly step expands left to right from 6 mm to 11 mm. A third step starts with a width of 7 mm. Bottom image is end ‘b’ with black arrows indicating location of chop marks. Barham et al. (2023).

The second item is a Sausagewood branch, with a side branch 37.9 cm in length, tapering from a 12.3 cm wide base to a 2.1 cm wide tip. The wood has been split centrally, and has a transverse chop mark above the tip. The purpose of this artefact is unclear.

Images of split branch, BLB4 (‘notched stick’). Above, close-up of the facet/chop-mark with arrow indicating direction of initiation. Below, all views of split branch with chop (white arrow) and close-up of the entry facet. The object was found cracked in situ. Barham et al. (2023).

The Kalambo Falls site has yielded a number of exceptionally well-preserved, intentionally modified wooded objects, with the most recent discoveries confidently dated to the Middle Pleistocene (and previous, undated discoveries likely to be of similar vintage). This has significant implications for our understanding of the technological capabilities of earlier members of the genus Homo, which have previously only been known from stone tools. The implications are clearly that these people were capable of felling large trees, and constructing objects such as platforms, which would have required considerable skills in selecting trees, felling them, and processing the wood obtained. Since this appears to have been done with stone tools, it shows that stone- and woodworking evolved together, and helps to explain some of the larger stone tools produced as part of the Acheulean technology. 

Between about 470 000 and about 274 000 years ago the Kalambo Falls site would have had an extensive forest cover and a high water table, leading to periodic flooding of the river plain. In such an environment the ability to produce raised platforms, wooden walkways, or even structures with solid foundations would have been highly advantageous.

The invention of hafted tools (tools with wooden handles) is thought to have occurred between about 500 000 and about 200 000 years ago, and would have required a good understanding of the properties of wood, and how to shape it by chopping and scraping. The interlocking logs at the lowest dated level at Kalambo Falls show a similar level of technological cognition, as well as a previously unanticipated ability to create the first built environments.

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