The archaeological results of Prehistoric societies obtained in the Archaeological Map of North Morocco Project

This paper presents the results of the “Archaeological Map in Northern Morocco” project, which has been carried out by researchers from the University of Cadiz, University of Abdelmalek Essaadi and INSAP of Rabat. Four seasons of archaeological survey have taken place in the Tetouan region as well as excavations in the Cave El Hafa and the rock-shelter of Marsa. This study includes geomorphological data and a petrographic study to pinpoint of the origins of raw material used by the different human groups that duelled in the area. Lastly, this paper presents settlement patterns of the studied groups, most importantly, this is an updated study of the relevant occupations that correspond to Palaeolithic hunter-gatherer societies, Neolithic tribal societies and also, of human settlements associated to Recent Prehistory stages.     

The complex structure of hunter-gatherer social networks

In nature, many different types of complex system form hierarchical, self-similar or fractal-like structures that have evolved to maximize internal efficiency. In this paper, we ask whether hunter-gatherer societies show similar structural properties. We use fractal network theory to analyse the statistical structure of 1189 social groups in 339 hunter-gatherer societies from a published compilation of ethnographies. We show that population structure is indeed self-similar or fractal-like with the number of individuals or groups belonging to each successively higher level of organization exhibiting a constant ratio close to 4. Further, despite the wide ecological, cultural and historical diversity of hunter-gatherer societies, this remarkable self-similarity holds both within and across cultures and continents. We show that the branching ratio is related to density-dependent reproduction in complex environments and hypothesize that the general pattern of hierarchical organization reflects the self-similar properties of the networks and the underlying cohesive and disruptive forces that govern the flow of material resources, genes and non-genetic information within and between social groups. Our results offer insight into the energetics of human sociality and suggest that human social networks self-organize in response to similar optimization principles found behind the formation of many complex systems in nature.     

Ancient DNA perspectives on American colonization and population history

Ancient DNA (aDNA) analyses have proven to be important tools in understanding human population dispersals, settlement patterns, interactions between prehistoric populations, and the development of regional population histories. Here, we review the published results of sixty-three human populations from throughout the Americas and compare the levels of diversity and geographic patterns of variation in the ancient samples with contemporary genetic variation in the Americas in order to investigate the evolution of the Native American gene pool over time. Our analysis of mitochondrial haplogroup frequencies and prehistoric population genetic diversity presents a complex evolutionary picture. Although the broad genetic structure of American prehistoric populations appears to have been established relatively early, we nevertheless identify examples of genetic discontinuity over time in select regions. We discuss the implications this finding may have for our interpretation of the genetic evidence for the initial colonization of the Americas and its subsequent population history.     

The Organization of Male and Female Labor in Foraging Societies: Implications for Early Paleoindian Archaeology

I use cross-cultural ethnographic data to explore the relationship between male and female subsistence labor among hunter-gatherer populations by examining data regarding resource procurement, time allocation, and task differentiation between the sexes relative to dependence on hunted foods. The findings indicate that female foragers generally perform a variety of nonsubsistence collection activities and preferentially procure high-return resources in hunting-based economies. I develop ideas about predictable relationships concerning the amount of time female foragers expend on subsistence and technological tasks relative to the dietary contribution of meat. I then use ethnographic trends to evaluate archaeological assumptions regarding the sexual division of labor in prehistoric foraging contexts, focusing on the dichotomous views of Clovis labor organization. I argue that archaeological interpretations of prehistoric labor roles in hunting-based foraging societies are commonly polarized between stereotypical views of male and female subsistence behaviors. I develop an interpretation of Early Paleoindian labor organization, emphasizing female labor in the production of material goods and the procurement of low-risk plant and animal resources based on global economic trends among foragers.     

Network dynamics of the nonlinear power-law relaxation of cell cortex

Living cells are known to exhibit universal power-law rheological behaviors, but their underlying biomechanical principles are still not fully understood. Here, we present a network dynamics picture to decipher the nonlinear power-law relaxation of cortical cytoskeleton. Under step strains, we present a scaling relation between instantaneous differential stiffness and external stress as a result of chain reorientation. Then, during the relaxation, we show how the scaling law theoretically originates from an exponential form of cortical disorder, with the scaling exponent decreased by the imposed strain or crosslinker density in the nonlinear regime. We attribute this exponent variation to the molecular realignment along the stretch direction or the transition of network structure from in-series to in-parallel modes, both solidifying the network toward our one-dimensional theoretical limit. In addition, the rebinding of crosslinkers is found to be crucial for moderating the relaxation speed under small strains. Together with the disorder nature, we demonstrate that the structural effects of networks provide a unified interpretation for the nonlinear power-law relaxation of cell cortex, and may help to understand cell mechanics from the molecular scale.     

Diet and dental caries among later stone age inhabitants of the Cape Province, South Africa.

Stable carbon isotope measurements and incidences of dental caries are presented for three groups of prehistoric human skeletons from different regions of the Cape Province, South Africa. The isotopic analyses of bone collagen demonstrate the importance of marine foods in the diet and vary through time, across space, and according to sex. The incidence of dental caries ranges from 0% among heavily marine-dependent individuals from the south-western Cape coast, to 17.7% among skeletons from an archaeological site on the south coast. The extremely high incidence of caries in a hunter-gatherer population may be related to lack of fluoride in the water.     

Settlement Hierarchies and Political Complexity in Nonmarket Societies: The Formative Period of the Valley of Mexico

Archaeologists have long recognized that increases in political centralization often coincide with the growth of regional settlement hierarchies. Here I develop a theoretical model which explicitly relates certain aspects of political complexity to variation in settlement size. This model applies specifically to hierarchical societies without well-developed market economies—societies which Service would classify as chiefdoms and (perhaps) simple states. Using settlement data from the Formative Period Valley of Mexico, I show how this model is useful in measuring (1) the number of levels in a regional hierarchy, (2) the degree of political centralization, and (3) the relative amount of surplus food mobilized to support the political establishment.     

大城市边缘区人居环境系统演变的生态-地理过程——以广州市为例

生态-地理过程(Eco-geographic process,EGP)是现代生态学、地理学与人居环境科学交叉与融合的重要研究方向。阐述了人居环境系统演变的内涵,并指出人居环境系统演变一般是从乡村人居环境,到边缘区人居环境,再到核心区人居环境,由此形成一个不可逆的演替序列。在此基础上,以广州市为例,综合运用生态学与地理学等分析方法,从边缘区与核心区、乡村人居环境系统及外部环境相互作用的角度,将人居环境系统演变的生态-地理过程划分为4类,即入侵(渗透、跳跃、蚕食、延伸)、竞争(分化和共生)、反应和调控,并构建了大城市边缘区人居环境系统演变的生态-地理过程概念模型。生态-地理过程研究对理解大城市边缘区演变机理与生态调控具有重要的理论价值与实践意义。     

Cultural ecology of prehistoric parasitism on the Colorado Plateau as evidenced by coprology

The study of coprolites (desiccated feces) is recognized as a viable method for analyzing parasitism of prehistoric peoples. Eight species of helminth parasites, including nematodes, cestodes, and acanthcephalans, have been recovered from archaeological sites on the Colorado Plateau. The comparative analysis of parasitological findings illustrates the effects of changing subsistence strategies and varying life-style on prehistoric human parasitism. This comparative study is based on the analysis of coprolites recovered from one Archaic hunter-gatherer site and two Anasazi agricultural villages. Hunter-gatherers are represented by coprolites from Dust Devil Cave in south-eastern Utah. Coprolites of prehistoric agriculturalists from Antelope House in Canyon de Chelly, Arizona, and from Salmon Ruin in northwestern New Mexico were studied. The results demonstrate that helminth parasitism increased with the advent of agriculture. Between the agricultural sites, differences in patterns of excreta disposal, foraging behavior, and local ecology resulted in pronounced variations in both percentage of coprolites containing parasite remains and the number of parasite species represented.     

A multilevel analytical framework for studying cultural evolution in prehistoric hunter–gatherer societies

Over the past decade, a major debate has taken place on the underpinnings of cultural changes in human societies. A growing array of evidence in behavioural and evolutionary biology has revealed that social connectivity among populations and within them affects, and is affected by, culture. Yet the interplay between prehistoric hunter–gatherer social structure and cultural transmission has typically been overlooked. Interestingly, the archaeological record contains large data sets, allowing us to track cultural changes over thousands of years: they thus offer a unique opportunity to shed light on long‐term cultural transmission processes. In this review, we demonstrate how well‐developed methods for social structure analysis can increase our understanding of the selective pressures underlying cumulative culture. We propose a multilevel analytical framework that considers finer aspects of the complex social structure in which regional groups of prehistoric hunter–gatherers were embedded. We put forward predictions of cultural transmission based on local‐ and global‐level network metrics of small‐scale societies and their potential effects on cumulative culture. By bridging the gaps between network science, palaeodemography and cultural evolution, we draw attention to the use of the archaeological record to depict patterns of social interactions and transmission variability. We argue that this new framework will contribute to improving our understanding of social interaction patterns, as well as the contexts in which cultural changes occur. Ultimately, this may provide insights into the evolution of human behaviour.     

海岛型城市人居环境质量评价——基于厦门市和平潭综合实验区的对比

21世纪是海洋世纪,海岛地位日益凸显,人居环境是海岛型城市发展质量的重要表征,然而目前学术界针对海岛城市人居环境质量评价的成果还较为鲜见。基于人居环境理论,构建了海岛型城市人居环境质量评价体系,选取厦门市和平潭综合实验区两个处于不同发展阶段的典型海岛型城市作为研究对象,综合评价了两个城市人居环境质量及动态变化。结果显示:(1)厦门和平潭人居环境质量均处于稳定提升状态,厦门人居环境宜居度更高,二者差距呈增大趋势;(2)城市人居环境系统与城市经济子系统二者存在相互协调、制衡的关系,不同发展阶段的协调度呈现一定的差异;(3)海岛城市人居环境质量受到自然、人类、社会、居住和支撑系统等5个子系统的综合影响,且各个子系统在不同发展阶段对人居环境的贡献率有所不同,发展初期的平潭人居环境自然子系统呈负向发展,人类子系统变化不大,社会、居住和支撑子系统得分贡献有所增加;而发展相对成熟的厦门人居环境自然子系统稳定性高,人类子系统虽呈上升趋势但变化幅度较小,社会子系统、居住子系统以及支撑子系统总体状况较好。研究可为厦门市和平潭综合实验区及国内同类海岛城市人居环境优化调控提供借鉴,同时丰富人居环境评估的实证案例与相关理论。     

The genetic signature of sex-biased migration in patrilocal chimpanzees and humans

A large body of theoretical work suggests that analyses of variation at the maternally inherited mitochondrial (mt)DNA and the paternally inherited non-recombining portion of the Y chromosome (NRY) are a potentially powerful way to reveal the differing migratory histories of men and women across human societies. However, the few empirical studies comparing mtDNA and NRY variation and known patterns of sex-biased migration have produced conflicting results. Here we review some methodological reasons for these inconsistencies, and take them into account to provide an unbiased characterization of mtDNA and NRY variation in chimpanzees, one of the few mammalian taxa where males routinely remain in and females typically disperse from their natal groups. We show that patterns of mtDNA and NRY variation are more strongly contrasting in patrilocal chimpanzees compared with patrilocal human societies. The chimpanzee data we present here thus provide a valuable comparative benchmark of the patterns of mtDNA and NRY variation to be expected in a society with extremely female-biased dispersal.     

Scaling laws of ambush predator ‘waiting’ behaviour are tuned to a common ecology

The decisions animals make about how long to wait between activities can determine the success of diverse behaviours such as foraging, group formation or risk avoidance. Remarkably, for diverse animal species, including humans, spontaneous patterns of waiting times show random ‘burstiness’ that appears scale-invariant across a broad set of scales. However, a general theory linking this phenomenon across the animal kingdom currently lacks an ecological basis. Here, we demonstrate from tracking the activities of 15 sympatric predator species (cephalopods, sharks, skates and teleosts) under natural and controlled conditions that bursty waiting times are an intrinsic spontaneous behaviour well approximated by heavy-tailed (power-law) models over data ranges up to four orders of magnitude. Scaling exponents quantifying ratios of frequent short to rare very long waits are species-specific, being determined by traits such as foraging mode (active versus ambush predation), body size and prey preference. A stochastic–deterministic decision model reproduced the empirical waiting time scaling and species-specific exponents, indicating that apparently complex scaling can emerge from simple decisions. Results indicate temporal power-law scaling is a behavioural ‘rule of thumb’ that is tuned to species’ ecological traits, implying a common pattern may have naturally evolved that optimizes move–wait decisions in less predictable natural environments.     

Tooth wear and compensatory modification of the anterior dentoalveolar complex in humans

In populations living in environments where teeth wear severely, some compensatory modification of the dentoalveolar complex is thought to occur during life whereby functional occlusion is maintained as tooth substance is lost by wear. This study investigates one aspect of this modification process: Changes in the anterior dentoalveolar complex that are accompanied with wear were examined in a series of Japanese skeletal samples. In the prehistoric Japanese hunter-gatherer population heavy wear occurs over the entire dentition. The following changes were demonstrated to have occurred in the anterior segment of the dentition accompanied by wear on the anterior teeth: The anterior teeth tip lingually with wear up to a nearly upright position to fill in interproximal spaces that would have been generated by wear, and to maintain contact relations between adjacent teeth. At the same time, the anterior surface of the maxillary alveolar process also inclines lingually to a certain extent. The amount of lingual tipping is greater in the maxillary anterior teeth than in their mandibular antagonists. It is because of this discrepancy that, with age, the horizontal component of the overlap between maxillary and mandibular anterior teeth decreases, and their bite form changes from scissor bite to edge-to-edge bite. Lesser degrees of lingual tipping of the anterior teeth were also detected in the prehistoric agriculturists and historic Japanese populations. The variation in the degree of lingual tipping observed among the samples is explained by inter-population variation in severity and pattern of tooth wear. This and other evidence suggests that mechanisms that compensate for wear in the anterior dentition may be characteristic of all living human populations, independently of the degree of wear severity endured in their environments.     

Human settlement and baobab distribution in south-western Mali

Aim Human settlement establishment and reproduction of the baobab tree (Adansonia digitata) appear spatially and temporally dependent because baobabs are abundant in many settlement sites in Africa. This paper tests the spatiotemporal relationship between baobab and settlement distribution. Location South‐western Mali. Methods In an area of 183 km², 1240 baobabs were located and mapped, their diameters measured, and habitat characteristics recorded for each individual. All occupied (n = 9) and abandoned (n = 84) settlements were located and mapped, and occupation dates were determined through interviews. Chi‐squared analysis indicated baobab habitat preferences, and bivariate point‐pattern analysis tested baobab–settlement spatiotemporal independence. Results Baobabs and human settlements are positively spatially associated at most distances and for all baobab size‐class–settlement age‐class pairs. However, positive spatial association is significant only at distances < 500 m, and young settlements and large baobabs are not significantly associated. Positive association between small and large baobabs is marginally significant at <300 m, but observed significance is less than that for baobab–settlement positive association. Baobab abundance is not evenly distributed across the range of habitats it occupies; recruitment is strongest in settlements and fields, and on cliffs, while mortality is highest on cliffs. Ethnographic observations suggest that human settlement practices and fruit use are the main human factors contributing to baobab–settlement positive spatial association. Main conclusions There are three main conclusions: (1) Human settlement and baobab recruitment are spatially dependant because settlement leads directly and indirectly to the development of baobab groves at settlement sites. (2) The lower than expected abundance of mature individuals in natural habitats, and the habitat preferences of the observed population, suggest that baobabs were introduced to south‐western Mali, probably centuries ago. (3) Human mobility over decadal time‐scales is necessary to maintain baobab population structure in landscapes dominated by shifting land use, where baobabs are not purposefully planted. Baobab population processes in such landscapes occur at the scale of human settlement.     

Network scaling reveals consistent fractal pattern in hierarchical mammalian societies

Recent studies have demonstrated that human societies are hierarchically structured with a consistent scaling ratio across successive layers of the social network; each layer of the network is between three and four times the size of the preceding (smaller) grouping level. Here we show that similar relationships hold for four mammalian taxa living in multi-level social systems. For elephant (Loxodonta africana), gelada (Theropithecus gelada) and hamadryas (Papio hamadryas hamadryas) baboon, successive layers of social organization have a scaling ratio of almost exactly 3, indicating that such branching ratios may be a consistent feature of all hierarchically structured societies. Interestingly, the scaling ratio for orca (Orcinus orca) was 3.8, which might mean that aquatic environments place different constraints on the organization of social hierarchies. However, circumstantial evidence from a range of other species suggests that scaling ratios close to 3 may apply widely, even in species where hierarchical social structures have not traditionally been identified. These results identify the origin of the hierarchical, fractal-like organization of mammalian social systems as a fundamental question.     

Revisiting the variation of clustering coefficient of biological networks suggests new modular structure

ABSTRACT: A central idea in biology is the hierarchical organization of cellular processes. A commonly used method to identify the hierarchical modular organization of network relies on detecting a global signature known as variation of clustering coefficient (so-called modularity scaling). Although several studies have suggested other possible origins of this signature, it is still widely used nowadays to identify hierarchical modularity, especially in the analysis of biological networks. Therefore, a further and systematical investigation of this signature for different types of biological networks is necessary. RESULTS: We analyzed a variety of biological networks and found that the commonly used signature of hierarchical modularity is actually the reflection of spoke-like topology, suggesting a different view of network architecture. We proved that the existence of super-hubs is the origin that the clustering coefficient of a node follows a particular scaling law with degree k in metabolic networks. To study the modularity of biological networks, we systematically investigated the relationship between repulsion of hubs and variation of clustering coefficient. We provided direct evidences for repulsion between hubs being the underlying origin of the variation of clustering coefficient, and found that for biological networks having no anti-correlation between hubs, such as gene co-expression network, the clustering coefficient doesn't show dependence of degree. CONCLUSIONS: Here we have shown that the variation of clustering coefficient is neither sufficient nor exclusive for a network to be hierarchical. Our results suggest the existence of spoke-like modules as opposed to "deterministic model" of hierarchical modularity, and suggest the need to reconsider the organizational principle of biological hierarchy.     

Population Migration and the Variation of Dopamine D4 Receptor (DRD4) Allele Frequencies Around the Globe

This article reports an association between the variation of dopamine D4 receptor (DRD4) allele frequencies around the globe and population migration patterns in prehistoric times. After compiling existing data on DRD4 allele frequencies of 2,320 individuals from 39 populations and on the migration pattern of these groups, we found that, compared to sedentary populations, migratory populations showed a higher proportion of long alleles for DRD4. The correlation between macro-migration (long-distance group migration) and the proportion of long alleles of DRD4 was .85 (p < .001), and that between micro-migration (sedentary vs. nomadic settlement) and the proportion of long alleles was .52 (p = .001). We discussed the adaptive value of long alleles of DRD4—a genetic trait that has been linked in some studies to the personality trait of novelty-seeking and to hyperactivity— in migratory societies and the possibility of natural selection for a migration gene.     

The Place of "Others" in Hunter-Gatherer Intensification

Archaeologists are interested in understanding the conditions under which hunter-gatherer intensification occurs. Typically, most models assign primacy to population pressure or social relations and address intensification as it occurs among foragers inhabiting arid or temperate environments. In this article, I explore episodes of resource intensification and "deintensification" on the subarctic island of Newfoundland. Correlating periods of resource intensification and "deintensification" with changes in the social landscape, I argue that the presence or absence of "Others" played a significant role in informing hunter-gatherer subsistence strategies and settlement patterns.