Jan Apel

Genomic Diversity and Admixture Differs for Stone-Age Scandinavian Foragers and Farmers

Hunters and Farmers The Neolithic period in Europe saw the transition from a hunter-gatherer lifestyle to farming. Previous genetic analyses have suggested that hunter-gatherers were replaced by immigrant farmers. Skoglund et al. (p. 747, published online 24 April) sequenced one Mesolithic and nine Neolithic Swedish individuals to examine the transition from hunter-gatherers to farmers. Substantial genetic differentiation was observed between hunter-gatherers and farmers: There was lower genetic diversity within the hunter-gatherers and gene flow from the hunter-gatherers into the farmers but not vice versa. Population dynamics of Scandinavian Mesolithic and Neolithic hunter-gatherers differ from those of early farmers. Prehistoric population structure associated with the transition to an agricultural lifestyle in Europe remains a contentious idea. Population-genomic data from 11 Scandinavian Stone Age human remains suggest that hunter-gatherers had lower genetic diversity than that of farmers. Despite their close geographical proximity, the genetic differentiation between the two Stone Age groups was greater than that observed among extant European populations. Additionally, the Scandinavian Neolithic farmers exhibited a greater degree of hunter-gatherer–related admixture than that of the Tyrolean Iceman, who also originated from a farming context. In contrast, Scandinavian hunter-gatherers displayed no significant evidence of introgression from farmers. Our findings suggest that Stone Age foraging groups were historically in low numbers, likely owing to oscillating living conditions or restricted carrying capacity, and that they were partially incorporated into expanding farming groups.

The Manipulative Complexity of Lower Paleolithic Stone Toolmaking

Background Early stone tools provide direct evidence of human cognitive and behavioral evolution that is otherwise unavailable. Proper interpretation of these data requires a robust interpretive framework linking archaeological evidence to specific behavioral and cognitive actions. Methodology/Principal Findings Here we employ a data glove to record manual joint angles in a modern experimental toolmaker (the 4th author) replicating ancient tool forms in order to characterize and compare the manipulative complexity of two major Lower Paleolithic technologies (Oldowan and Acheulean). To this end we used a principled and general measure of behavioral complexity based on the statistics of joint movements. Conclusions/Significance This allowed us to confirm that previously observed differences in brain activation associated with Oldowan versus Acheulean technologies reflect higher-level behavior organization rather than lower-level differences in manipulative complexity. This conclusion is consistent with a scenario in which the earliest stages of human technological evolution depended on novel perceptual-motor capacities (such as the control of joint stiffness) whereas later developments increasingly relied on enhanced mechanisms for cognitive control. This further suggests possible links between toolmaking and language evolution.

Technology, expertise and social cognition in human evolution

Paleolithic stone tools provide concrete evidence of major developments in human behavioural and cognitive evolution. Of particular interest are evolving cognitive mechanisms implied by the cultural transmission of increasingly complex prehistoric technologies, hypothetically including motor resonance, causal reasoning and mentalizing. To test the relevance of these mechanisms to specific Paleolithic technologies, we conducted a functional magnetic resonance imaging study of Naïve, Trained and Expert subjects observing two toolmaking methods of differing complexity and antiquity: the simple ‘Oldowan’ method documented by the earliest tools 2.5 million years ago; and the more complex ‘Acheulean’ method used to produce refined tools 0.5 million years ago. Subjects observed 20‐s video clips of an expert demonstrator, followed by behavioural tasks designed to maintain attention. Results show that observational understanding of Acheulean toolmaking involves increased demands for the recognition of abstract technological intentions. Across subject groups, Acheulean compared with Oldowan toolmaking was associated with activation of left anterior intraparietal and inferior frontal sulci, indicating the relevance of resonance mechanisms. Between groups, Naïve subjects relied on bottom‐up kinematic simulation in the premotor cortex to reconstruct unfamiliar intentions, and Experts employed a combination of familiarity‐based sensorimotor matching in the posterior parietal cortex and top‐down mentalizing involving the medial prefrontal cortex. While no specific differences between toolmaking technologies were found for Trained subjects, both produced frontal activation relative to Control, suggesting focused engagement with toolmaking stimuli. These findings support motor resonance hypotheses for the evolutionary origins of human social cognition and cumulative culture, directly linking these hypotheses with archaeologically observable behaviours in prehistory.

Genomics of Mesolithic Scandinavia reveal colonization routes and high-latitude adaptation

Scandinavia was one of the last geographic areas in Europe to become habitable for humans after the last glaciation. However, the origin(s) of the first colonizers and their migration routes remain unclear. We sequenced the genomes, up to 57x coverage, of seven hunter-gatherers excavated across Scandinavia and dated to 9,500-6,000 years before present. Surprisingly, among the Scandinavian Mesolithic individuals, the genetic data display an east-west genetic gradient that opposes the pattern seen in other parts of Mesolithic Europe. This result suggests that Scandinavia was initially colonized following two different routes: one from the south, the other from the northeast. The latter followed the ice-free Norwegian north Atlantic coast, along which novel and advanced pressure-blade stone-tool techniques may have spread. These two groups met and mixed in Scandinavia, creating a genetically diverse population, which shows patterns of genetic adaptation to high latitude environments. These adaptations include high frequencies of low pigmentation variants and a gene-region associated with physical performance, which shows strong continuity into modern-day northern Europeans.

Grammars of action in human behavior and evolution

Distinctive human behaviors from tool-making to language are thought to rely on a uniquely evolved capacity for hierarchical action sequencing. Unfortunately, testing of this idea has been hampered by a lack of objective, generalizable methods for measuring the structural complexity of real-world behaviors. Here we present a data-driven approach for quantifying hierarchical structure by extracting action grammars from basic ethograms. We apply this method to the evolutionarily-relevant behavior of stone tool-making by comparing sequences from the experimental replication of ˜2.5 Mya Oldowan vs. more recent ˜0.5 Mya Achuelean tools. Results show that, while using the same “alphabet” of elementary actions, Acheulean sequences are structurally more complex. Beyond its specific evolutionary implications, this finding illustrates the broader applicability of our method to investigate the structure of naturalistic human behaviors and cognition. We demonstrate one application by using our complexity measures to re-analyze data from an fMRI study of tool-making action observation.

Re-enacting the sequence: combined digital methods to study a prehistoric cave

This contribution seeks to demonstrate how recently developed 3D GIS platforms can help archeologists in relating to the original context legacy data that can be employed to digitally reconstruct the sequence of arbitrary layers as it was observed and then excavated in the end of the nineteenth century. This research has been conducted on the prehistoric cave of Stora Förvar, located on the small island of Stora Karlsö, in South-Eastern Sweden. As a part of a research project titled “The pioneer settlements of Gotland,” this line of enquiry has sought to combine 3D-based digital acquisition techniques, Geographical Information Systems (GIS), and old archival material (hand-made drawings, artifacts lists, historical pictures) in order to virtually reconstruct the original sequence as it was excavated through the method of arbitrary layers. At a later stage, the reconstructed sequence has been employed to re-contextualize and analyze the distribution of artifacts so as to detect any possible pattern that could have been useful for defining the chronological boundaries of the Mesolithic phase of habitation of the cave. In brief, three main objectives can be defined: (a) to re-create a spatial connection between the artifacts retrieved at the time of the excavation and the sequence of layers, (b) to define density maps showing the relationship between volumes of layers and categories of artifacts belonging to the sequence, and (c) to further our knowledge about the Mesolithic habitation of the cave, not only vertically (chronologically) but also horizontally.

Botanical evidence of malt for beer production in fifth–seventh century Uppåkra, Sweden

The excavation of a low-temperature kiln structure at an affluent Iron Age regional center, Uppåkra, located in southern Sweden, revealed from archeobotanical samples and its context evidence of malting in the process to make beer. Carbonized germinated hulled barley grain (Hordeum vulgare) was recovered from the kiln structure itself and from the surrounding occupational surface. Located somewhat from the central area of the site, where previous excavations have uncovered hall-buildings, a ceremonial structure, and several smaller houses, the investigated kiln was situated in an area on the site that is absent of remains to indicate a living quarter. Activities using kilns have instead primarily been linked to this area and archeological finds are mainly of charred crops remains. In this paper, we argue that the germination of grain was deliberate and that the kiln was used to stop the germination process by drying or roasting the grain. If the malting process for large-scale beer production was carried out at a designated area of the site is discussed, as well as if this activity area was part of a structural organization observed elsewhere on the settlement.

Catherine Frieman & Berit Valentin Eriksen (ed.). Flint daggers in prehistoric Europe . 2015. viii+165 pages, numerous colour and bw 978-1-78570-018-7 hardback £40.

This collection of papers examines the regional variability and socio-technical complexity of Neolithic flint daggers in Europe and beyond. The volume is well edited, the language fluent and most of the figures are nicely reproduced, including some in colour. Following an introduction, 12 papers cover daggers from the Near East, southern and western Europe, northern Europe, southern Scandinavia and eastern Europe; a chapter dealing with the Bronze Age metal and stone daggers of north-east Asia falls somewhat outside the book’s general theme—even if it is interesting in its own right. A conclusion summarises some of the threads running through the contributions, and points towards future research. A huge amount of detailed information is presented in the papers, and this review can touch upon only a few of the many interesting aspects covered.