Millennia
The resilience of postglacial hunter-gatherers to abrupt climate change
Simon Blockley et al.
Nature Ecology & Evolution, May 2018, Pages 810–818
Abstract:
Understanding the resilience of early societies to climate change is an essential part of exploring the environmental sensitivity of human populations. There is significant interest in the role of abrupt climate events as a driver of early Holocene human activity, but there are very few well-dated records directly compared with local climate archives. Here, we present evidence from the internationally important Mesolithic site of Star Carr showing occupation during the early Holocene, which is directly compared with a high-resolution palaeoclimate record from neighbouring lake beds. We show that — once established — there was intensive human activity at the site for several hundred years when the community was subject to multiple, severe, abrupt climate events that impacted air temperatures, the landscape and the ecosystem of the region. However, these results show that occupation and activity at the site persisted regardless of the environmental stresses experienced by this society. The Star Carr population displayed a high level of resilience to climate change, suggesting that postglacial populations were not necessarily held hostage to the flickering switch of climate change. Instead, we show that local, intrinsic changes in the wetland environment were more significant in determining human activity than the large-scale abrupt early Holocene climate events.
“Many Seasons Ago”: Slavery and Its Rejection among Foragers on the Pacific Coast of North America
David Wengrow & David Graeber
American Anthropologist, forthcoming
Abstract:
Anthropologists have traditionally classified foragers on the Pacific coast of North America into two major culture areas, characterized by strikingly different social and ethical systems. These are “California” and the adjacent “Northwest Coast.” Foragers in the northern part of California exhibit many elements of Weber's “Protestant ethic,” such as the moral injunction for community leaders to work hard, seek spiritual purpose by introspection, and pursue monetary wealth while avoiding material excess. By contrast, the social organization of Northwest Coast foragers bears comparison with that of courtly estates in medieval Europe, where a leisured class of nobles achieved status through hereditary ranking, competitive banquets, dazzling aesthetic displays, and the retention of household slaves captured in war. Remarkably, the coexistence of two such clearly opposed value systems among foragers inhabiting adjacent parts of the Pacific littoral has excited little interest in anthropologists, historians, or archaeologists to date. We consider the implications, which cast doubt on some key orthodoxies concerning the nature of culture areas, modes of subsistence, and political evolution. We argue that the political creativity of foraging peoples has been severely underrated.
Body size downgrading of mammals over the late Quaternary
Felisa Smith et al.
Science, 20 April 2018, Pages 310-313
Abstract:
Since the late Pleistocene, large-bodied mammals have been extirpated from much of Earth. Although all habitable continents once harbored giant mammals, the few remaining species are largely confined to Africa. This decline is coincident with the global expansion of hominins over the late Quaternary. Here, we quantify mammalian extinction selectivity, continental body size distributions, and taxonomic diversity over five time periods spanning the past 125,000 years and stretching approximately 200 years into the future. We demonstrate that size-selective extinction was already under way in the oldest interval and occurred on all continents, within all trophic modes, and across all time intervals. Moreover, the degree of selectivity was unprecedented in 65 million years of mammalian evolution. The distinctive selectivity signature implicates hominin activity as a primary driver of taxonomic losses and ecosystem homogenization. Because megafauna have a disproportionate influence on ecosystem structure and function, past and present body size downgrading is reshaping Earth’s biosphere.
Pre-Columbian earth-builders settled along the entire southern rim of the Amazon
Jonas Gregorio de Souza et al.
Nature Communications, March 2018
Abstract:
The discovery of large geometrical earthworks in interfluvial settings of southern Amazonia has challenged the idea that Pre-Columbian populations were concentrated along the major floodplains. However, a spatial gap in the archaeological record of the Amazon has limited the assessment of the territorial extent of earth-builders. Here, we report the discovery of Pre-Columbian ditched enclosures in the Tapajós headwaters. The results show that an 1800 km stretch of southern Amazonia was occupied by earth-building cultures living in fortified villages ~Cal AD 1250–1500. We model earthwork distribution in this broad region using recorded sites, with environmental and terrain variables as predictors, estimating that earthworks will be found over ~400,000 km2 of southern Amazonia. We conclude that the interfluves and minor tributaries of southern Amazonia sustained high population densities, calling for a re-evaluation of the role of this region for Pre-Columbian cultural developments and environmental impact.
Homo sapiens in Arabia by 85,000 years ago
Huw Groucutt et al.
Nature Ecology & Evolution, May 2018, Pages 800–809
Abstract:
Understanding the timing and character of the expansion of Homo sapiens out of Africa is critical for inferring the colonization and admixture processes that underpin global population history. It has been argued that dispersal out of Africa had an early phase, particularly ~130–90 thousand years ago (ka), that reached only the East Mediterranean Levant, and a later phase, ~60–50 ka, that extended across the diverse environments of Eurasia to Sahul. However, recent findings from East Asia and Sahul challenge this model. Here we show that H. sapiens was in the Arabian Peninsula before 85 ka. We describe the Al Wusta-1 (AW-1) intermediate phalanx from the site of Al Wusta in the Nefud desert, Saudi Arabia. AW-1 is the oldest directly dated fossil of our species outside Africa and the Levant. The palaeoenvironmental context of Al Wusta demonstrates that H. sapiens using Middle Palaeolithic stone tools dispersed into Arabia during a phase of increased precipitation driven by orbital forcing, in association with a primarily African fauna. A Bayesian model incorporating independent chronometric age estimates indicates a chronology for Al Wusta of ~95–86 ka, which we correlate with a humid episode in the later part of Marine Isotope Stage 5 known from various regional records. Al Wusta shows that early dispersals were more spatially and temporally extensive than previously thought. Early H. sapiens dispersals out of Africa were not limited to winter rainfall-fed Levantine Mediterranean woodlands immediately adjacent to Africa, but extended deep into the semi-arid grasslands of Arabia, facilitated by periods of enhanced monsoonal rainfall.
Terminal Pleistocene epoch human footprints from the Pacific coast of Canada
Duncan McLaren et al.
PLoS ONE, March 2018
Abstract:
Little is known about the ice age human occupation of the Pacific Coast of Canada. Here we present the results of a targeted investigation of a late Pleistocene shoreline on Calvert Island, British Columbia. Drawing upon existing geomorphic information that sea level in the area was 2–3 m lower than present between 14,000 and 11,000 years ago, we began a systematic search for archaeological remains dating to this time period beneath intertidal beach sediments. During subsurface testing, we uncovered human footprints impressed into a 13,000-year-old paleosol beneath beach sands at archaeological site EjTa-4. To date, our investigations at this site have revealed a total of 29 footprints of at least three different sizes. The results presented here add to the growing body of information pertaining to the early deglaciation and associated human presence on the west coast of Canada at the end of the Last Glacial Maximum.
Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins
Elaine Kozma et al.
Proceedings of the National Academy of Sciences, 17 April 2018, Pages 4134-4139
Abstract:
The evolutionary emergence of humans’ remarkably economical walking gait remains a focus of research and debate, but experimentally validated approaches linking locomotor capability to postcranial anatomy are limited. In this study, we integrated 3D morphometrics of hominoid pelvic shape with experimental measurements of hip kinematics and kinetics during walking and climbing, hamstring activity, and passive range of hip extension in humans, apes, and other primates to assess arboreal–terrestrial trade-offs in ischium morphology among living taxa. We show that hamstring-powered hip extension during habitual walking and climbing in living apes and humans is strongly predicted, and likely constrained, by the relative length and orientation of the ischium. Ape pelves permit greater extensor moments at the hip, enhancing climbing capability, but limit their range of hip extension, resulting in a crouched gait. Human pelves reduce hip extensor moments but permit a greater degree of hip extension, which greatly improves walking economy (i.e., distance traveled/energy consumed). Applying these results to fossil pelves suggests that early hominins differed from both humans and extant apes in having an economical walking gait without sacrificing climbing capability. Ardipithecus was capable of nearly human-like hip extension during bipedal walking, but retained the capacity for powerful, ape-like hip extension during vertical climbing. Hip extension capability was essentially human-like in Australopithecus afarensis and Australopithecus africanus, suggesting an economical walking gait but reduced mechanical advantage for powered hip extension during climbing.
Supraorbital morphology and social dynamics in human evolution
Ricardo Miguel Godinho, Penny Spikins & Paul O’Higgins
Nature Ecology & Evolution, forthcoming
Abstract:
Uniquely, with respect to Middle Pleistocene hominins, anatomically modern humans do not possess marked browridges, and have a more vertical forehead with mobile eyebrows that play a key role in social signalling and communication. The presence and variability of browridges in archaic Homo species and their absence in ourselves have led to debate concerning their morphogenesis and function, with two main hypotheses being put forward: that browridge morphology is the result of the spatial relationship between the orbits and the brain case; and that browridge morphology is significantly impacted by biting mechanics. Here, we virtually manipulate the browridge morphology of an archaic hominin (Kabwe 1), showing that it is much larger than the minimum required to fulfil spatial demands and that browridge size has little impact on mechanical performance during biting. As browridge morphology in this fossil is not driven by spatial and mechanical requirements alone, the role of the supraorbital region in social communication is a potentially significant factor. We propose that conversion of the large browridges of our immediate ancestors to a more vertical frontal bone in modern humans allowed highly mobile eyebrows to display subtle affiliative emotions.
Human bony labyrinth is an indicator of population history and dispersal from Africa
Marcia Ponce de León et al.
Proceedings of the National Academy of Sciences, 17 April 2018, Pages 4128-4133
Abstract:
The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype–phenotype comparisons.
Changes in mandible characteristics during the terminal Pleistocene to Holocene Levant and their association with dietary habits
Hila May et al.
Journal of Archaeological Science: Reports, forthcoming
Abstract:
The Levant is characterized by changes in human economic behavior and subsistence strategies, following the transition from a hunting and gathering society in terminal Pleistocene to a settled, agricultural society in the Holocene. Using an advanced approach previously recognized to be associated to some extent with masticatory system function, we aimed to examine the morphological changes in the mandible during these periods and determine whether they were associated with reduced demands of mastication force. Three major prehistoric populations of the Levant were studied: Natufian hunter-gatherers (n = 41), early farmers Pre-pottery Neolithic (n = 28), and Chalcolithic farmers (n = 13), samples of which are housed in the Anthropological collection at the Sackler Faculty of Medicine, TAU. A modern population was included as a control group (n = 61). Two types of measurements were carried out using CT scans of the mandibles: size measurements: 14 linear and cross-sectional area (CSA) measurements; and orientation measurements: four angular measurements. One Way ANOVA or Kruskal-Wallis tests were carried out to examine differences in measurements between the studied groups. Our results show a reduction in mandibular size during the last 15 thousand years, although some reduction occurred only after the Chalcolithic period. In addition, the mandibular body became positioned more upright and the mandibular angle increased. Some of the changes observed can be associated with mastication loadings. We therefore concluded that the ongoing reduced demand on the masticatory system during the Holocene was probably due to a softer diet, resulting in dramatic changes in the mandibular size and orientation. Moreover, we offer a set of measurement parameters that can be reliably used for the analyses of archaeological populations when studying dietary habits.