Natives
Genetic signature of natural selection in first Americans
Carlos Eduardo Amorim et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases (FADS) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a protein-rich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments.
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Hemorrhagic fever virus, human blood, and tissues in Iron Age mortuary vessels
Conner Wiktorowicz et al.
Journal of Archaeological Science, February 2017, Pages 29-39
Abstract:
This study identifies and interprets the proteins present on sherds from six ceramic mortuary vessels from a burial mound near the Heuneburg, an early Iron Age (750-400 BCE) hillfort in southwest Germany, using a novel adaptation of proteomic analysis that identified 166 proteins with high confidence. Surprisingly, among the identified proteins were peptides from Crimean-Congo hemorrhagic fever virus (CCHFV), a pathogen previously unknown in this geographic region and time period, as well as peptides from human blood and tissues. These results highlight the first example of a viral cause of death of at least one high-status individual from the Iron Age west-central Europe and provide the first archaeological evidence for the interment of human organs in mortuary vessels in the region. We also demonstrate the suitability and value of a proteomics approach for discovery-based residue analysis of archaeological ceramic vessels and reveal how identification of adsorbed proteins can provide insight into prehistoric mortuary practices.
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Midcontinental Native American population dynamics and late Holocene hydroclimate extremes
Broxton Bird et al.
Scientific Reports, January 2017
Abstract:
Climate’s influence on late Pre-Columbian (pre-1492 CE), maize-dependent Native American populations in the midcontinental United States (US) is poorly understood as regional paleoclimate records are sparse and/or provide conflicting perspectives. Here, we reconstruct regional changes in precipitation source and seasonality and local changes in warm-season duration and rainstorm events related to the Pacific North American pattern (PNA) using a 2100-year-long multi-proxy lake-sediment record from the midcontinental US. Wet midcontinental climate reflecting negative PNA-like conditions occurred during the Medieval Climate Anomaly (950-1250 CE) as Native American populations adopted intensive maize agriculture, facilitating population aggregation and the development of urban centers between 1000-1200 CE. Intensifying midcontinental socio-political instability and warfare between 1250-1350 CE corresponded with drier positive PNA-like conditions, culminating in the staggered abandonment of many major Native American river valley settlements and large urban centers between 1350-1450 CE during an especially severe warm-season drought. We hypothesize that this sustained drought interval rendered it difficult to support dense populations and large urban centers in the midcontinental US by destabilizing regional agricultural systems, thereby contributing to the host of socio-political factors that led to population reorganization and migration in the midcontinent and neighboring regions shortly before European contact.
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Modeling the role of voyaging in the coastal spread of the Early Neolithic in the West Mediterranean
Neus Isern et al.
Proceedings of the National Academy of Sciences, 31 January 2017, Pages 897-902
Abstract:
The earliest dates for the West Mediterranean Neolithic indicate that it expanded across 2,500 km in about 300 y. Such a fast spread is held to be mainly due to a demic process driven by dispersal along coastal routes. Here, we model the Neolithic spread in the region by focusing on the role of voyaging to understand better the core elements that produced the observed pattern of dates. We also explore the effect of cultural interaction with Mesolithic populations living along the coast. The simulation study shows that (i) sea travel is required to obtain reasonable predictions, with a minimum sea-travel range of 300 km per generation; (ii) leapfrog coastal dispersals yield the best results (quantitatively and qualitatively); and (iii) interaction with Mesolithic people can assist the spread, but long-range voyaging is still needed to explain the archaeological pattern.
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Impact of pre-Columbian “geoglyph” builders on Amazonian forests
Jennifer Watling et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Over 450 pre-Columbian (pre-AD 1492) geometric ditched enclosures (“geoglyphs”) occupy ∼13,000 km2 of Acre state, Brazil, representing a key discovery of Amazonian archaeology. These huge earthworks were concealed for centuries under terra firme (upland interfluvial) rainforest, directly challenging the “pristine” status of this ecosystem and its perceived vulnerability to human impacts. We reconstruct the environmental context of geoglyph construction and the nature, extent, and legacy of associated human impacts. We show that bamboo forest dominated the region for ≥6,000 y and that only small, temporary clearings were made to build the geoglyphs; however, construction occurred within anthropogenic forest that had been actively managed for millennia. In the absence of widespread deforestation, exploitation of forest products shaped a largely forested landscape that survived intact until the late 20th century.