Examining cut mark residue with SEM to identify metal tool use: An experimental study.

In this manuscript, we explore the potential of studying metal residues in cut marks generated by copper and bronze knives. The method was developed in the forensic sciences for use with modern metals in order to identify microscopic particles of metal tools on bone surfaces. However, the study of residues in archaeological materials can be challenging due to the ways in which the bone remains may have been manipulated, both in the past and in more recent times. Using a scanning electron microscope (SEM), we detected microscopic fragments of bronze and copper knives along with contamination both inside and outside of the cut marks made by those knives. Copper and bronze residues were identified embedded in the bone inside the incisions and, in two cases, they left greenish stains caused by metal oxidation. In contrast, modern contamination of undetermined origin was found unattached to the bone and had a chemical composition not compatible with that of the knives. The amount of residue was influenced by the quantity of soft tissue between the bone and the knife during the butchering tasks. Bone cooking does not seem to influence the preservation of the residues. We anticipate that the approach used in this first exploratory study will emerge as a promising method for identifying the use of metal tools in archaeological bone remains.

The limestone spheroids of 'Ubeidiya: intentional imposition of symmetric geometry by early hominins?

Spheroids are one of the least understood lithic items yet are one of the most enduring, spanning from the Oldowan to the Middle Palaeolithic. Why and how they were made remains highly debated. We seek to address whether spheroids represent unintentional by-products of percussive tasks or if they were intentionally knapped tools with specific manufacturing goals. We apply novel three-dimensional analysis methods, including spherical harmonics and surface curvature, to 150 limestone spheroids from 'Ubeidiya (ca 1.4 Ma), presently the earliest Acheulean occurrence outside of Africa, to bring a new perspective to these enigmatic artefacts. We reconstruct the spheroid reduction sequence based on trends in their scar facets and geometry, finding that the spheroid makers at 'Ubeidiya followed a premeditated reduction strategy. During their manufacture, the spheroids do not become smoother, but they become markedly more spherical. They approach an ideal sphere, a feat that likely required skilful knapping and a preconceived goal. Acheulean bifaces are currently thought to represent the earliest evidence of hominins imposing a premeditated, symmetrical shape on stone. The intentional production of sphere-like objects at 'Ubeidiya similarly shows evidence of Acheulean hominins desiring and achieving intentional geometry and symmetry in stone.

Subspheroids in the lithic assemblage of Barranco León (Spain): Recognizing the late Oldowan in Europe.

The lithic assemblage of Barranco León (BL), attributed to the Oldowan techno-complex, contributes valuable information to reconstruct behavioral patterning of the first hominins to disperse into Western Europe. This archaic stone tool assemblage comprises two, very different groups of tools, made from distinct raw materials. On the one hand, a small-sized toolkit knapped from Jurassic flint, comprising intensively exploited cores and small-sized flakes and fragments and, on the other hand, a large-sized limestone toolkit that is mainly linked to percussive activities. In recent years, the limestone macro-tools have been the center of particular attention, leading to a re-evaluation of their role in the assemblage. Main results bring to light strict hominin selective processes, mainly concerning the quality of the limestone and the morphology of the cobbles, in relation to their use-patterning. In addition to the variety of traces of percussion identified on the limestone tools, recurrences have recently been documented in their positioning and in the morphology of the active surfaces. Coupled with experimental work, this data has contributed to formulating hypothesis about the range of uses for these tools, beyond stone knapping and butchery, for activities such as: wood-working or tendon and meat tenderizing. The abundance of hammerstones, as well as the presence of heavy-duty scrapers, are special features recognized for the limestone component of the Barranco León assemblage. This paper presents, for the first time, another characteristic of the assemblage: the presence of polyhedral and, especially, subspheroid morphologies, virtually unknown in the European context for this timeframe. We present an analysis of these tools, combining qualitative evaluation of the raw materials, diacritical study, 3D geometric morphometric analysis of facet angles and an evaluation of the type and position of percussive traces; opening up the discussion of the late Oldowan beyond the African context.

The genomic history of the Iberian Peninsula over the past 8000 years.

We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula. We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming. We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia's ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry. We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European-speaking regions but also into non-Indo-European-speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean.

Genome-wide patterns of selection in 230 ancient Eurasians.

Ancient DNA makes it possible to observe natural selection directly by analysing samples from populations before, during and after adaptation events. Here we report a genome-wide scan for selection using ancient DNA, capitalizing on the largest ancient DNA data set yet assembled: 230 West Eurasians who lived between 6500 and 300 bc, including 163 with newly reported data. The new samples include, to our knowledge, the first genome-wide ancient DNA from Anatolian Neolithic farmers, whose genetic material we obtained by extracting from petrous bones, and who we show were members of the population that was the source of Europe's first farmers. We also report a transect of the steppe region in Samara between 5600 and 300 bc, which allows us to identify admixture into the steppe from at least two external sources. We detect selection at loci associated with diet, pigmentation and immunity, and two independent episodes of selection on height.

Limestone percussion tools from the late Early Pleistocene sites of Barranco León and Fuente Nueva 3 (Orce, Spain).

In recent years, there is growing interest in the study of percussion scars and breakage patterns on hammerstones, cores and tools from Oldowan African and Eurasian lithic assemblages. Oldowan stone toolkits generally contain abundant small-sized flakes and their corresponding cores, and are characterized by their structural dichotomy of heavy- and light-duty tools. This paper explores the significance of the lesser known heavy-duty tool component, providing data from the late Lower Pleistocene sites of Barranco León and Fuente Nueva 3 (Orce, Spain), dated 1.4-1.2 Myr. Using quantitative and qualitative data from the large-sized limestone industries from these two major sites, we present a new methodology highlighting their morpho-technological features. In the light of the results, we discuss the shortfalls of extant classificatory methods for interpreting the role of percussive technology in early toolkits. This work is rooted in an experimental program designed to reproduce the wide range of percussion marks observed on the limestone artefacts from these two sites. A visual and descriptive reference is provided as an interpretative aid for future comparative research. Further experiments using a variety of materials and gestures are still needed before the elusive traces yield the secrets of the kinds of percussive activities carried out by hominins at these, and other, Oldowan sites.

Mitochondrial DNA from El Mirador cave (Atapuerca, Spain) reveals the heterogeneity of Chalcolithic populations.

Previous mitochondrial DNA analyses on ancient European remains have suggested that the current distribution of haplogroup H was modeled by the expansion of the Bell Beaker culture (ca 4,500-4,050 years BP) out of Iberia during the Chalcolithic period. However, little is known on the genetic composition of contemporaneous Iberian populations that do not carry the archaeological tool kit defining this culture. Here we have retrieved mitochondrial DNA (mtDNA) sequences from 19 individuals from a Chalcolithic sample from El Mirador cave in Spain, dated to 4,760-4,200 years BP and we have analyzed the haplogroup composition in the context of modern and ancient populations. Regarding extant African, Asian and European populations, El Mirador shows affinities with Near Eastern groups. In different analyses with other ancient samples, El Mirador clusters with Middle and Late Neolithic populations from Germany, belonging to the Rössen, the Salzmünde and the Baalberge archaeological cultures but not with contemporaneous Bell Beakers. Our analyses support the existence of a common genetic signal between Western and Central Europe during the Middle and Late Neolithic and points to a heterogeneous genetic landscape among Chalcolithic groups.

Age and date for early arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain).

The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.

The first evidence of cut marks and usewear traces from the Plio-Pleistocene locality of El-Kherba (Ain Hanech), Algeria: implications for early hominin subsistence activities circa 1.8 Ma.

The current archaeological data on early hominin subsistence activities in Africa are derived chiefly from Sub-Saharan Plio-Pleistocene sites. The recent studies at El-Kherba (Ain Hanech) in northeastern Algeria expand the geographic range of evidence of hominin subsistence patterns to include the earliest known archaeological sites documented in North Africa. Dated to 1.78 million years ago (Ma), excavations from El-Kherba yielded an Oldowan industry associated with a savanna-like fauna contained in floodplain deposits. The faunal assemblage is dominated by large and medium-sized animals (mainly adults), especially equids, which are represented by at least 11 individuals. The mammalian archaeofauna preserves numerous cut-marked and hammerstone-percussed bones. Made of primarily limestone and flint, the stone assemblage consists of core forms, débitage, and retouched pieces. Evidence of usewear traces is found on several of the flint artifacts, indicating meat processing by early hominins. Overall, our subsistence analysis indicates that early hominins were largely responsible for bone modification at the site, which is also corroborated by other relevant taphonomic evidence. Moreover, at 1.78 Ma, the cutmarked bones recovered from El-Kherba represent the earliest known evidence for ancestral hominin butchery activities and large animal foraging capabilities in northern Africa.