Risk, Uncertainty, and Violence in Eastern Africa

Previous research on warfare in a worldwide sample of societies by Ember and Ember (Journal of Conflict Resolution, 36, 242–262, 1992a) found a strong relationship between resource unpredictability (particularly food scarcity caused by natural disasters) in nonstate, nonpacified societies and overall warfare frequency. Focusing on eastern Africa, a region frequently plagued with subsistence uncertainty as well as violence, this paper explores the relationships between resource problems, including resource unpredictability, chronic scarcity, and warfare frequencies. It also examines whether resource scarcity predicts more resource-taking in land, movable property, and people, as well as the commission of atrocities. Results support previous worldwide results regarding the relationship between resource unpredictability and warfare frequency. Results regarding resource-taking and atrocities are more nuanced and complex. In almost all findings, relationships are generally in opposite directions in nonstate and state societies. In post-hoc analyses, atrocities are significantly more likely to be committed in states than in nonstates.     

High Selection Pressure Promotes Increase in Cumulative Adaptive Culture

The evolution of cumulative adaptive culture has received widespread interest in recent years, especially the factors promoting its occurrence. Current evolutionary models suggest that an increase in population size may lead to an increase in cultural complexity via a higher rate of cultural transmission and innovation. However, relatively little attention has been paid to the role of natural selection in the evolution of cultural complexity. Here we use an agent-based simulation model to demonstrate that high selection pressure in the form of resource pressure promotes the accumulation of adaptive culture in spite of small population sizes and high innovation costs. We argue that the interaction of demography and selection is important, and that neither can be considered in isolation. We predict that an increase in cultural complexity is most likely to occur under conditions of population pressure relative to resource availability. Our model may help to explain why culture change can occur without major environmental change. We suggest that understanding the interaction between shifting selective pressures and demography is essential for explaining the evolution of cultural complexity.     

Long-term land-cover changes in the Belgian Ardennes (1775–1929): model-based reconstruction vs. historical maps

Understanding long‐term human‐environment interactions requires historical reconstruction of past land‐cover changes. The objective of this study is to reconstruct past land‐use and land‐cover changes in a rural municipality of the Belgian Ardennes over the last 250 years. Two approaches were compared. The first approach produced backward projections based on a mechanistic model which computes the demand for different land uses under the assumption of an equilibrium between the production and consumption of resources. The second approach involved using a series of historical maps to extract directly land‐use areas. A stochastic Markov chain model was also used to project backward missing land‐cover data in the time series. The consistency between the results obtained with the different approaches suggests that land‐use area can be successfully reconstructed on the basis of the mechanistic model, under conditions of a subsistence farming system and a closed economy. Land‐use/cover changes in the Belgian Ardennes from 1775 to 1929 were more driven by the interventionist measures of the Belgian government and by technological progress than by the ‘pressure’ of the growing population and livestock. Thanks to agricultural intensification, a decrease in land under human use was supporting increasing human and livestock populations from 1846 to 1880. Reforestation has accelerated since the mid‐19th century. This case study illustrates the highly dynamic and non‐linear character of land‐use change trajectories over long time periods and their strong interactions with the history of societies.     

Cooperation,collective action,and the archeology of large‐scale societies

Archeologists investigating the emergence of large‐scale societies in the past have renewed interest in examining the dynamics of cooperation as a means of understanding societal change and organizational variability within human groups over time. Unlike earlier approaches to these issues, which used models designated voluntaristic or managerial, contemporary research articulates more explicitly with frameworks for cooperation and collective action used in other fields, thereby facilitating empirical testing through better definition of the costs, benefits, and social mechanisms associated with success or failure in coordinated group action. Current scholarship is nevertheless bifurcated along lines of epistemology and scale, which is understandable but problematic for forging a broader, more transdisciplinary field of cooperation studies. Here, we point to some areas of potential overlap by reviewing archeological research that places the dynamics of social cooperation and competition in the foreground of the emergence of large‐scale societies, which we define as those having larger populations, greater concentrations of political power, and higher degrees of social inequality. We focus on key issues involving the communal‐resource management of subsistence and other economic goods, as well as the revenue flows that undergird political institutions. Drawing on archeological cases from across the globe, with greater detail from our area of expertise in Mesoamerica, we offer suggestions for strengthening analytical methods and generating more transdisciplinary research programs that address human societies across scalar and temporal spectra.     

Mode and tempo in the evolution of socio-political organization: reconciling 'Darwinian' and 'Spencerian' evolutionary approaches in anthropology

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of 'Spencerian' cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader 'Darwinian' framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification.     

Sociopolitical Complexity and the Bow and Arrow in the American Southwest

The evolution of sociopolitical complexity, including heightened relations of cooperation and competition among large nonkin groups, has long been a central focus of anthropological research. 1 , 2 Anthropologists suggest any number of variables that affect the waxing and waning of complexity and define the precise trajectories that groups take, including population density, subsistence strategies, warfare, the distribution of resources, and trade relationships. 3 , 4 Changes in weaponry, here the introduction of the bow and arrow, can have profound implications for population aggregation and density, subsistence and settlement strategies, and access to resources, trade, and warfare. 5 Bingham and Souza provide a general conceptual model for the relationship between complexity and the bow and arrow, arguing that this compound weapon system, whereby smaller projectiles travel at higher speed and are capable of hitting targets more accurately and at greater distances than hand‐thrown darts, fundamentally favors the formation of larger groups because it allows for cost‐effective means of dealing with conflicts of interest through social coercion, thereby dramatically transforming kin‐based social relations. 6 Here we consider the impacts the introduction of the bow and arrow had on sociopolitical complexity in the North American Southwest.     

The spread of inequality

The causes of socioeconomic inequality have been debated since the time of Plato. Many reasons for the development of stratification have been proposed, from the need for hierarchical control over large-scale irrigation systems to the accumulation of small differences in wealth over time via inheritance processes. However, none of these explains how unequal societies came to completely displace egalitarian cultural norms over time. Our study models demographic consequences associated with the unequal distribution of resources in stratified societies. Agent-based simulation results show that in constant environments, unequal access to resources can be demographically destabilizing, resulting in the outward migration and spread of such societies even when population size is relatively small. In variable environments, stratified societies spread more and are also better able to survive resource shortages by sequestering mortality in the lower classes. The predictions of our simulation are provided modest support by a range of existing empirical studies. In short, the fact that stratified societies today vastly outnumber egalitarian societies may not be due to the transformation of egalitarian norms and structures, but may instead reflect the more rapid migration of stratified societies and consequent conquest or displacement of egalitarian societies over time.     

Sexual dimorphism in stature and women's work: a phylogenetic cross-cultural analysis.

The following cultural variables were tested for their association with sexual dimorphism: sexual division of labor, type of subsistence (hunting and agriculture), and polygyny. The transmission of these traits among populations was investigated. All the traits were found to be associated with phylogeny, indicating that they are inherited from mother to daughter populations. A cross-cultural comparative method was used which controls for the statistical effects of similarity due to common ancestry (Galton's problem). Cross-cultural variation in sexual dimorphism in stature is negatively associated with women's contribution to subsistence. Women are taller, relative to men, in societies where women contribute more to food production. This may be because female nutritional status is better in these societies. No relationship was found between sexual dimorphism and other aspects of subsistence or polygyny. These results are discussed in relation to other studies of sexual dimorphism in modern and archaeological populations, and in relation to cross-cultural variation in sex-biased parental investment.     

Hunter‐gatherer mobility and embedded raw‐material procurement strategies in the mediterranean upper paleolithic

Since the early 1980s, the sourcing of lithic raw materials has become central to studies of the territorial range and mobility strategies of Pleistocene foraging societies. Results have been fruitful but somehow repetitive. We will discuss the embedded procurement strategy, which presumes that raw material acquisition was part of other subsistence activities rather than an autonomous technological task. We argue that this theoretical assumption, when taken as dogma, restricts the role of technology in human history and also underestimates the way some lithic resources may have affected the organization of past hunter‐gatherers. We base our discussion on the Upper Paleolithic (UP) from the Liguro‐Provençal arc, with examples from the Proto‐Aurignacian and the Epigravettian. Our regional record shows that in this context the movement of rocks over distances greater than 100 km was the norm rather than the exception. We argue that these long‐distance procurements mirror technical needs that were oriented toward the selection of high‐quality flints. We support the hypothesis that indirect procurement was an important component of regional socio‐economic networks.     

The Dynamics of Latifundia Formation

Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.     

Subsistence and the Evolution of Religion

We present a cross-cultural analysis showing that the presence of an active or moral High God in societies varies generally along a continuum from lesser to greater technological complexity and subsistence productivity. Foragers are least likely to have High Gods. Horticulturalists and agriculturalists are more likely. Pastoralists are most likely, though they are less easily positioned along the productivity continuum. We suggest that belief in moral High Gods was fostered by emerging leaders in societies dependent on resources that were difficult to manage and defend without group cooperation. These leaders used the concept of a supernatural moral enforcer to manipulate others into cooperating, which resulted in greater productivity. Reproductive success would accrue most to such leaders, but the average reproductive success of all individuals in the society would also increase with greater productivity. Supernatural enforcement of moral codes maintained social cohesion and allowed for further population growth, giving one society an advantage in competition with others.     

Modeling Agricultural Production Strategies in the Northern Rio Grande Valley, New Mexico

Diversification in agricultural techniques is a common strategy of risk minimization in nonindustrial societies. However, attribution of suboptimal behavior to risk minimization without consideration of the structure of risk and its environmental context obscures the complexity of agricultural decision-making. The productive potential of a prehistoric agricultural system that includes floodwater and dry farming and stream irrigation is modeled using Geographic Information System (GIS) analysis to evaluate whether diversification occurred as a response to population pressure or as a risk buffering strategy. The estimated productive potential of floodwater and irrigation farming is sufficient to have supported the estimated local population, suggesting that risk buffering is a more likely explanation. Floodwater farming and stream irrigation form a dual strategy that is effective at reducing risk. However, the potential of dry farming for subsistence production is insufficient for buffering more than a 2% productive shortfall. We propose that, within this generally risk-averse economy, dry farming was oriented toward the production of nonsubsistence crops such as cotton.     

Habitat percolation transition undermines sustainability in social-ecological agricultural systems

Steady increases in human population size and resource consumption are driving rampant agricultural expansion and intensification. Habitat loss caused by agriculture puts the integrity of ecosystems at risk and threatens the persistence of human societies that rely on ecosystem services. We develop a spatially explicit model describing the coupled dynamics of an agricultural landscape and human population size to assess the effect of different land-use management strategies, defined by agricultural clustering and intensification, on the sustainability of the social-ecological system. We show how agricultural expansion can cause natural habitats to undergo a percolation transition leading to abrupt habitat fragmentation that feedbacks on human's decision making, aggravating landscape degradation. We found that agricultural intensification to spare land from conversion is a successful strategy only in highly natural landscapes, and that clustering agricultural land is the most effective measure to preserve large connected natural fragments, prevent severe fragmentation and thus, enhance sustainability.     

From small holes to grand narratives: the impact of taphonomy and sample size on the modernity debate in Australia and New Guinea

Our knowledge of early Australasian societies has significantly expanded in recent decades with more than 220 Pleistocene sites reported from a range of environmental zones and depositional contexts. The uniqueness of this dataset has played an increasingly important role in global debates about the origins and expression of complex behaviour among early modern human populations. Nevertheless, discussions of Pleistocene behaviour and cultural innovation are yet to adequately consider the effects of taphonomy and archaeological sampling on the nature and representativeness of the record. Here, we investigate the effects of preservation and sampling on the archaeological record of Sahul, and explore the implications for understanding early cultural diversity and complexity. We find no evidence to support the view that Pleistocene populations of Sahul lacked cognitive modernity or cultural complexity. Instead, we argue that differences in the nature of early modern human populations across the globe were more likely the consequence of differences in population size and density, interaction and historical contingency.     

Broad supernatural punishment but not moralizing high gods precede the evolution of political complexity in Austronesia

Supernatural belief presents an explanatory challenge to evolutionary theorists—it is both costly and prevalent. One influential functional explanation claims that the imagined threat of supernatural punishment can suppress selfishness and enhance cooperation. Specifically, morally concerned supreme deities or ‘moralizing high gods'' have been argued to reduce free-riding in large social groups, enabling believers to build the kind of complex societies that define modern humanity. Previous cross-cultural studies claiming to support the MHG hypothesis rely on correlational analyses only and do not correct for the statistical non-independence of sampled cultures. Here we use a Bayesian phylogenetic approach with a sample of 96 Austronesian cultures to test the MHG hypothesis as well as an alternative supernatural punishment hypothesis that allows punishment by a broad range of moralizing agents. We find evidence that broad supernatural punishment drives political complexity, whereas MHGs follow political complexity. We suggest that the concept of MHGs diffused as part of a suite of traits arising from cultural exchange between complex societies. Our results show the power of phylogenetic methods to address long-standing debates about the origins and functions of religion in human society.     

Historical links between settlement,ecology, and politics in the mountains of west Nepal

The paper presents a study of settlement processes in western Nepal. It emphasizes the linkages between settlement history, cultural ecology, and political economy as these relate to resources, marginality, and territory. Regional settlement trends are examined in accordance with land occupancy and tenure arrangements. Village settlement strategies are analyzed within a micro-processual framework that incorporates political economic perspectives on village land use and resource distributions. The past, present, and future roles of settlement in the human adaptation process of west Nepal's mountain populations is critically examined in the contexts of historical land policies and current rural political and environmental systems.     

Cross-border Comparison of Post-socialist Farmland Abandonment in the Carpathians

Agricultural areas are declining in many areas of the world, often because socio-economic and political changes make agriculture less profitable. The transition from centralized to market-oriented economies in Eastern Europe and the former Soviet Union after 1989 represented major economic and political changes, yet the resulting rates and spatial pattern of post-socialist farmland abandonment remain largely unknown. Remote sensing offers unique opportunities to map farmland abandonment, but automated assessments are challenging because phenology and crop types often vary substantially. We developed a change detection method based on support vector machines (SVM) to map farmland abandonment in the border triangle of Poland, Slovakia, and Ukraine in the Carpathians from Landsat TM/ETM+ images from 1986, 1988, and 2000. Our SVM-based approach yielded an accurate change map (overall accuracy = 90.9%; kappa = 0.82), underpinning the potential of SVM to map complex land-use change processes such as farmland abandonment. Farmland abandonment was widespread in the study area (16.1% of the farmland used in socialist times), likely due to decreasing profitability of agriculture after 1989. We also found substantial differences in abandonment among the countries (13.9% in Poland, 20.7% in Slovakia, and 13.3% in Ukraine), and between previously collectivized farmland and farmland that remained private during socialism in Poland. These differences are likely due to differences in socialist land ownership patterns, post-socialist land reform strategies, and rural population density.     

Evolution of monogamous marriage by maximization of inclusive fitness

The majority of human societies allow polygynous marriage, and the prevalence of this practice is readily understood in evolutionary terms. Why some societies prescribe monogamous marriage is however not clear: current evolutionary explanations—that social monogamy increases within‐group co‐operation, giving societies an advantage in competition with other groups—conflict with the historical and ethnographic evidence. We show that, within the framework of inclusive fitness theory, monogamous marriage can be viewed as the outcome of the strategic behaviour of males and females in the allocation of resources to the next generation. Where resources are transferred across generations, social monogamy can be advantageous if partitioning of resources among the offspring of multiple wives causes a depletion of their fitness value, and/or if females grant husbands higher fidelity in exchange for exclusive investment of resources in their offspring. This may explain why monogamous marriage prevailed among the historical societies of Eurasia: here, intensive agriculture led to scarcity of land, with depletion in the value of estates through partitioning among multiple heirs. Norms promoting high paternity were common among ancient societies in the region, and may have further facilitated the establishment of social monogamy. In line with the historical and ethnographic evidence, this suggests that monogamous marriage emerged in Eurasia following the adoption of intensive agriculture, as ownership of land became critical to productive and reproductive success.