Palaeoenvironmental, epigraphic and archaeological evidence of total warfare among the Classic Maya
David Wahl et al.
Nature Human Behaviour, forthcoming
Despite over a century of archaeological research, the nature and broader consequences of Maya warfare remain poorly understood. Classic period (250–950 CE) Maya warfare has largely been viewed as ritualized and limited in scope. Evidence of violent warfare in the Terminal Classic period (800–950 CE) is interpreted as an escalation of military tactics that played a role in the socio-economic collapse of the Classic Maya civilization. The implications of specific textual references to war events (war statements) remain unknown, however, and the paucity of field data precludes our ability to test collapse theories tied to warfare. Here we connect a massive fire event to an attack described with a Classic period war statement. Multiple lines of evidence show that a large fire occurred across the ancient city of Witzna, coincident with an epigraphic account describing an attack and burning of Witzna in 697 CE. Following this event, evidence shows a dramatic decline in human activity, indicating extensive negative impacts on the local population. These findings provide insight into strategies and broader societal impacts of Classic period warfare, clarify the war statement’s meaning and show that the Maya engaged in tactics akin to total warfare earlier and more frequently than previously thought.
Natural selection contributed to immunological differences between hunter-gatherers and agriculturalists
Genelle Harrison et al.
Nature Ecology & Evolution, August 2019, Pages 1253–1264
The shift from a hunter-gatherer to an agricultural mode of subsistence is believed to have been associated with profound changes in the burden and diversity of pathogens across human populations. Yet, the extent to which the advent of agriculture affected the evolution of the human immune system remains unknown. Here we present a comparative study of variation in the transcriptional responses of peripheral blood mononuclear cells to bacterial and viral stimuli between Batwa rainforest hunter-gatherers and Bakiga agriculturalists from Uganda. We observed increased divergence between hunter-gatherers and agriculturalists in the early transcriptional response to viruses compared with that for bacterial stimuli. We demonstrate that a significant fraction of these transcriptional differences are under genetic control and we show that positive natural selection has helped to shape population differences in immune regulation. Across the set of genetic variants underlying inter-population immune-response differences, however, the signatures of positive selection were disproportionately observed in the rainforest hunter-gatherers. This result is counter to expectations on the basis of the popularized notion that shifts in pathogen exposure due to the advent of agriculture imposed radically heightened selective pressures in agriculturalist populations.
Endogenous (in)formal institutions
Serra Boranbay & Carmine Guerriero
Journal of Comparative Economics, forthcoming
The paper provides a formal framework identifying both the origins and interaction of a culture of cooperation and inclusive political institutions. When elite members and citizens try to cooperate in sharing consumption risk and joint investment, the elite enacts democracy to convince the citizens that a sufficient part of the investment return will be shared via public spending and thus, they should cooperate. In addition, cultural accumulation rises with the severity of consumption risk at its moderate values and then drops at its high values making cheating too appealing. Finally, the citizens may over-accumulate culture to credibly commit to cooperating in investment at its intermediate values threatening democracy. These predictions are consistent with novel data on 90 European historical regions spanning the 1000–1600 period. Reforms towards tighter constraints on the elite’s power were driven by the potential for Mediterranean trades. Moreover, the activity of both the Cistercians and the Franciscans, our proxy for the citizens’ culture, has an inverted U-shaped link with the temperature volatility. Finally, the shift of long-distance trades towards the Atlantic fostered the Franciscans’ spread in the Mediterranean, where they organized micro-credit activities reinforcing the citizenry-elite partnerships.
Scales, weights and weight-regulated artefacts in Middle and Late Bronze Age Britain
The identification of weights and weight-regulated artefacts is of primary importance for confirming the existence of European Bronze Age value ratios and exchange systems. Until recently, however, no such Bronze Age artefacts had been identified in Britain. Here, statistical analysis identifies — for the first time — Middle and Late Bronze Age balance weights and weight-regulated gold objects from Britain, Ireland and Atlantic France. These finds allow for new interpretations concerning modes of exchange and their significance in Atlantic Europe, further underlining a Continental — and possibly Mediterranean — influence on Britain during the late second and early first millennia BC.
Genetic architecture and adaptations of Nunavik Inuit
Sirui Zhou et al.
Proceedings of the National Academy of Sciences, 6 August 2019, Pages 16012-16017
The Canadian Inuit have a distinct population background that may entail particular implications for the health of its individuals. However, the number of genetic studies examining this Inuit population is limited, and much remains to be discovered in regard to its genetic characteristics. In this study, we generated whole-exome sequences and genomewide genotypes for 170 Nunavik Inuit, a small and isolated founder population of Canadian Arctic indigenous people. Our study revealed the genetic background of Nunavik Inuit to be distinct from any known present-day population. The majority of Nunavik Inuit show little evidence of gene flow from European or present-day Native American peoples, and Inuit living around Hudson Bay are genetically distinct from those around Ungava Bay. We also inferred that Nunavik Inuit have a small effective population size of 3,000 and likely split from Greenlandic Inuit ∼10.5 kya. Nunavik Inuit went through a bottleneck at approximately the same time and might have admixed with a population related to the Paleo-Eskimos. Our study highlights population-specific genomic signatures in coding regions that show adaptations unique to Nunavik Inuit, particularly in pathways involving fatty acid metabolism and cellular adhesion (CPNE7, ICAM5, STAT2, and RAF1). Subsequent analyses in selection footprints and the risk of intracranial aneurysms (IAs) in Nunavik Inuit revealed an exonic variant under weak negative selection to be significantly associated with IA (rs77470587; P = 4.6 × 10−8).
Scaling of Hunter Gatherer Camp Size and Human Sociality
José Lobo et al.
Arizona State University Working Paper, May 2019
One of the most commonly-observed properties of human settlements, both past and present, is the tendency for larger settlements to display higher population densities. Work in urban science and archaeology suggests this densification pattern reflects an emergent spatial equilibrium where individuals balance movement costs with social interaction benefits, leading to increases in aggregate productivity and social interdependence. In this context, it is perhaps not surprising that the more temporary camps created by mobile hunters and gatherers exhibit a tendency to become less dense with their population size. Here we examine why this difference occurs and consider conditions under which hunter-gatherer groups may transition to sedentism and densification. We investigate the relationship between population and area in mobile hunter-gatherer camps using a dataset, representing a large cross-cultural sample, derived from the ethnographic literature. We present a model based on the interplay between social interactions and scalar stress for the relationship between camp area and group size that describes the observed patterns among mobile hunter-gatherers. The model highlights the tradeoffs between the costs and benefits of proximity and interaction that are common to all human aggregations and specifies the constraints that must be overcome for economies of scale and cooperation to emerge.