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Amazonia is an invaluable global asset for all its ecological and cultural significance. Indigenous peoples and their lands are pivotal in safeguarding this unique biodiversity and mitigating global climate change. Understanding the causal structure behind variation in the degree of environmental conservation across different indigenous lands–each with varying institutional, legal, and socioenvironmental conditions–is an essential source of information in the struggle for long-term sustainable management of Amazonian ecosystems. Here, we use data from the Instituto Socioambiental for 361 indigenous lands in the Brazilian Amazon coded for environmental integrity, territorial integrity, legal stability, indigenous governance, and threats due to infrastructure projects. Using Bayesian networks to learn the causal structure amongst these variables reveals two causal pathways leading to environmental integrity. One causal pathway starts with territorial integrity and is mediated by infrastructure projects, while the other is directly from legal stability. Hence, safeguarding indigenous lands from exploitation is best accomplished via legal land rights and stricter enforcement instead of placing the onus on indigenous governance, which is also a direct outcome of legal stability. [ABSTRACT FROM AUTHOR]

Isolated indigenous societies who actively avoid sustained peaceful contact with the outside world are critically endangered. Last year, "Tanaru", the lone surviving man of his tribe for at least 35 years, died in Southwest Amazonia, marking the latest cultural extinction event in a long history of massacres, enslavement, and epidemics. Yet in the upper reaches of the Amazon Basin, dozens of resilient isolated tribes still manage to survive. Remote sensing is a reliable method of monitoring the population dynamics of uncontacted populations by quantifying the area cleared for gardens and villages, along with the fire detections associated with the burning of those clearings. Remote sensing also provides a method to document the number of residential structures and village fissioning. Only with these longitudinal assessments can we better evaluate the current no-contact policies by the United Nations and governments, along with the prospects for the long-term survival of isolated tribes. While the world's largest isolated indigenous metapopulation, Pano speakers in Acre, Brazil, appears to be thriving, other smaller isolated populations disconnected from metapopulations continue to be extremely vulnerable to external threats. Our applied anthropological conservation approach is to provide analyses of publicly available remote sensing datasets to help inform policies that enhance the survival and well-being of isolated cultural groups. [ABSTRACT FROM AUTHOR]

We investigate 3D size-segregation in a granular avalanche. A thin bi-disperse avalanche is brought to rest within a confined geometry, forming a stationary deposit. The front of the stationary deposit propagates upslope as a shock in the flow thickness. The shock freezes the segregation state of the disperse avalanche at a given point into the deposit. 3D magnetic resonance images of the deposit have been acquired to obtain particle distribution characteristics. Significant gradients in lateral and downstream concentration profiles are observed. Initially, faster evolution of the segregation state occurs at the walls, with the core remaining closer to the inlet conditions. Ultimately, at larger flow distances, a core rich in large particles develops, with layers of predominantly small particles at the side-walls and base. Evidence from both graded and inversely graded inlet conditions suggests that the avalanches converge to the same stable segregation state for distances larger than ∼ 1300 large particle diameters. Crucially, the pure-small-particle layers that form at the base of the flows, whilst initially varying in thickness, converge towards the same constant thickness by the chute’s end wall. Although the non-constant thickness of the pure-small-particle layer at smaller flow distances is not always reported in prior work on chute avalanches, there is a good qualitative agreement on the evolution of the segregation state down the chute with prior studies. [ABSTRACT FROM AUTHOR]

Human societies exhibit a diversity of social organizations that vary widely in size, structure, and complexity. Today, human sociopolitical complexity ranges from stateless small-scale societies of a few hundred individuals to complex states of millions, most of this diversity evolving only over the last few hundred years. Understanding how sociopolitical complexity evolved over time and space has always been a central focus of the social sciences. Yet despite this long-term interest, a quantitative understanding of how sociopolitical complexity varies across cultures is not well developed. Here we use scaling analysis to examine the statistical structure of a global sample of over a thousand human societies across multiple levels of sociopolitical complexity. First, we show that levels of sociopolitical complexity are self-similar as adjacent levels of jurisdictional hierarchy see a four-fold increase in population size, a two-fold increase in geographic range, and therefore a doubling of population density. Second, we show how this self-similarity leads to the scaling of population size and geographic range. As societies increase in complexity population density is reconfigured in space and quantified by scaling parameters. However, there is considerable overlap in population metrics across all scales suggesting that while more complex societies tend to have larger and denser populations, larger and denser populations are not necessarily more complex. [ABSTRACT FROM AUTHOR]

The expansion of the human species out of Africa in the Pleistocene, and the subsequent development of agriculture in the Holocene, resulted in waves of linguistic diversification and replacement across the planet. Analogous to the growth of populations or the speciation of biological organisms, languages diversify over time to form phylogenies of language families. However, the dynamics of this diversification process are unclear. Bayesian methods applied to lexical and phonetic data have created dated linguistic phylogenies for 18 language families encompassing ~3,000 of the world’s ~7,000 extant languages. In this paper we use these phylogenies to quantify how fast languages expand and diversify through time both within and across language families. The overall diversification rate of languages in our sample is ~0.001 yr-1 (or a doubling time of ~700 yr) over the last 6,000 years with evidence for nonlinear dynamics in language diversification rates over time, where both within and across language families, diversity initially increases rapidly and then slows. The expansion, evolution, and diversification of languages as they spread around the planet was a non-constant process. [ABSTRACT FROM AUTHOR]

At least 50 indigenous groups spread across lowland South America remain isolated and have only intermittent and mostly hostile interactions with the outside world. Except in emergency situations, the current policy of governments in Brazil, Colombia, and Peru towards isolated tribes is a “leave them alone” strategy, in which isolated groups are left uncontacted. However, these no-contact policies are based on the assumption that isolated populations are healthy and capable of persisting in the face of mounting external threats, and that they can maintain population viability in the long-term. Here, we test this assumption by tracking the sizes and movements of cleared horticultural areas made by 8 isolated groups over the last 10–14 years. We used deforestation data derived from remote sensing Landsat satellite sensors to identify clearings, and those were then validated and assessed with high-resolution imagery. We found only a single example of a relatively large and growing population (c. 50 cleared ha and 400 people), whereas all of the other 7 groups exhibited much smaller villages and gardens with no sizable growth through time. These results indicated that the smaller groups are critically endangered, and it prompts an urgent re-thinking of policies toward isolated populations, including plans for well-organized contacts that may help save lives and rescue isolated indigenous populations from imminent extinction. [ABSTRACT FROM AUTHOR]

The headwaters of the Amazon Basin harbor most of the world’s last indigenous peoples who have limited contact with encroaching colonists. Knowledge of the geographic distribution of these isolated groups is essential to assist with the development of immediate protections for vulnerable indigenous settlements. We used remote sensing to document the locations of 28 isolated villages within the four Brazilian states of Acre, Amazonas, Roraima, and Rondônia. The sites were confirmed during previous over-flights and by image evidence of thatched-roof houses; they are estimated to host over 1,700 individuals. Locational data were used to train maximum entropy models that identified landscape and anthropogenic features associated with the occurrence of isolated indigenous villages, including elevation, proximity to streams of five different orders, proximity to roads and settlements, proximity to recent deforestation, and vegetation cover type. Isolated villages were identified at mid elevations, within 20 km of the tops of watersheds and at greater distances from existing roads and trails. We further used model results, combined with boundaries of the existing indigenous territory system that is designed to protect indigenous lands, to assess the efficacy of the existing protected area network for isolated peoples. Results indicate that existing indigenous territories encompass all of the villages we identified, and 50% of the areas with high predicted probabilities of isolated village occurrence. Our results are intended to help inform policies that can mitigate against future external threats to isolated peoples. [ABSTRACT FROM AUTHOR]

Some cross-cultural evidence suggests lethal coalitionary aggression in humans is the product of residence and descent rules that promote fraternal interest groups, i.e., power groups of coresident males bonded by kinship. As such, human lethal coalitions are hypothesized to be homologous to chimpanzee (Pan troglodytes) border patrols. However, humans demonstrate a unique metagroup social structure in which strategic alliances allow individuals toform coalitions transcending local community boundaries. We test predictions derived from the fraternal interest group and strategic alliance models using lethal coalition data from a lowland South American population, the Yanomamö. Yanomamö men who kill an enemy acquire a special status, termed unokai. We examine the social characteristics of co-unokais or men who jointly kill others. Analyses indicate co-unokais generally are (i) from the same population but from different villages and patrilines, (ii) close age mates, and (iii) maternal half-first cousins. Furthermore, the incident rate for co-unokai killings increases if men are similar in age, from the same population, and from different natal communities. Co-unokais who have killed more times in the past and who are more genetically related to each other have a higher probability of coresidence in adulthood. Last, a relationship exists between lethal coalition formation and marriage exchange. In this population, internal warfare unites multiple communities, and co-unokais strategically form new residential groups and marriage alliances. These results support the strategic alliance model of coalitionary aggression, demonstrate the complexities of human alliance formation, and illuminate key differences in social structure distinguishing humans from other primates. [ABSTRACT FROM AUTHOR]

This study examines the fluting of two well‐known Late Pleistocene fluted point types in North America: Clovis and Folsom. Using scaling analyses, we assess the changing relationship between flute length and point length in a large sample of each type. Researchers use scaling to investigate the physical constraints of an object and determine how its dimensions change with size. We compare the strength and consistency of the scaling relationships between the older Clovis and the younger Folsom with the aim of shedding light on scaling differences, if any, over their temporal span. Our results show that there is a significant difference in the relationship of fluting length to point length between these types. In Folsom point manufacture, flute length increases nearly twice as fast with increasing point length than in Clovis. Importantly, the scaling of flute length to point length relationship is isometric (linear) in the Folsom sample, whereas it is allometric (sublinear) in the Clovis sample. In other words, Folsom flintknappers maintained a constant ratio of flute length to point length. Clovis flintknappers were less concerned about maintaining this ratio. We attribute this difference to a potentially increasing, or changing, functional role of fluting in Folsom. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives: Greater Amazonia harbors as many as 100 locations of isolated indigenous peoples. Few options are available to assess the demographic health of these populations given their limited contact with the outside world. Remote sensing offers one option. Methods: An isolated village in Brazil near the Peruvian border is visible with Google Earth imagery from 2006. The area of the fields and village, as well as the living area of the four longhouses, are measured and compared to population-by-area measurements for 71 other Brazilian indigenous communities. Results: The estimated population of the village is no more than 40 people. A village as small as this one, if it has become disconnected from a metapopulation, risks imminent extinction if it has fallen below a minimum viable population size. Conclusions: An active remote surveillance program is urgently needed to track the movements and demographic health of isolated peoples in hopes of improving their dire chances for long-term survival. They need protected areas that are large enough to mitigate against external threats. Am. J. Hum. Biol. 26:570-572, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Across the planet the biogeographic distribution of human cultural diversity tends to correlate positively with biodiversity. In this paper we focus on the biogeographic distribution of mammal species and human cultural diversity. We show that not only are these forms of diversity similarly distributed in space, but they both scale superlinearly with environmental production. We develop theory that explains that as environmental productivity increases the ecological kinetics of diversity increases faster than expected because more complex environments are also more interactive. Using biogeographic databases of the global distributions of mammal species and human cultures we test a series of hypotheses derived from this theory and find support for each. For both mammals and cultures, we show that (1) both forms of diversity increase exponentially with ecological kinetics; (2) the kinetics of diversity is faster than the kinetics of productivity; (3) diversity scales superlinearly with environmental productivity; and (4) the kinetics of diversity is faster in increasingly productive environments. This biogeographic convergence is particularly striking because while the dynamics of biological and cultural evolution may be similar in principle the underlying mechanisms and time scales are very different. However, a common currency underlying all forms of diversity is ecological kinetics; the temperature-dependent fluxes of energy and biotic interactions that sustain all forms of life at all levels of organization. Diversity begets diversity in mammal species and human cultures because ecological kinetics drives superlinear scaling with environmental productivity. [ABSTRACT FROM AUTHOR]

Fundamental frequency (f o) is the most perceptually salient vocal acoustic parameter, yet little is known about how its perceptual influence varies across societies. We examined how f o affects key social perceptions and how socioecological variables modulate these effects in 2,647 adult listeners sampled from 44 locations across 22 nations. Low male f o increased men's perceptions of formidability and prestige, especially in societies with higher homicide rates and greater relational mobility in which male intrasexual competition may be more intense and rapid identification of high-status competitors may be exigent. High female f o increased women's perceptions of flirtatiousness where relational mobility was lower and threats to mating relationships may be greater. These results indicate that the influence of f o on social perceptions depends on socioecological variables, including those related to competition for status and mates. [ABSTRACT FROM AUTHOR]

The evolution of the hominin hand has been widely linked to the use and production of flaked stone tool technologies. After the earliest handheld flake tools emerged, shifts in hominin hand anatomy allowing for greater force during precision gripping and ease when manipulating objects in-hand are observed in the fossil record. Previous research has demonstrated how biometric traits, such as hand and digit lengths and precision grip strength, impact functional performance and ergonomic relationships when using flake and core technologies. These studies are consistent with the idea that evolutionary selective pressures would have favoured individuals better able to efficiently and effectively produce and use flaked stone tools. After the advent of composite technologies during the Middle Stone Age and Middle Palaeolithic, fossil evidence reveals differences in hand anatomy between populations, but there is minimal evidence for an increase in precision gripping capabilities. Furthermore, there is little research investigating the selective pressures, if any, impacting manual anatomy after the introduction of hafted composite stone technologies ('handles'). Here we investigated the possible influence of tool-user biometric variation on the functional performance of 420 hafted Clovis knife replicas. Our results suggest there to be no statistical relationships between biometric variables and cutting performance. Therefore, we argue that the advent of hafted stone technologies may have acted as a 'performance equaliser' within populations and removed (or reduced) selective pressures favouring forceful precision gripping capabilities, which in turn could have increased the relative importance of cultural evolutionary selective pressures in the determination of a stone tool's performance. [ABSTRACT FROM AUTHOR]

Researchers use a variety of target materials, and sometimes combinations of materials, in their archaeological experiments to examine thrust‐spear or projectile penetration, impact angle, durability, and other issues involving prehistoric hunting weaponry. This variety of target materials is beneficial to archaeological science in several ways, but it may also hinder the comparison of results because many of these target materials do not necessarily share similar physical properties. Here, we assess the penetration properties of four different target materials—store‐bought meat, clay, and two types of gelatin—via static penetration tests of a modern broadhead‐tipped arrow and a stone‐tipped projectile attached to an Instron Universal Materials Tester. Our analyses of load‐deflection curves, peak load, and work energy demonstrate how the four target materials are similar in some ways but different in others, which suggests that researchers may strategically employ one or several depending on the question asked or hypothesis tested. [ABSTRACT FROM AUTHOR]

The evolution of the hominin hand has been widely linked to the use and production of flaked stone tool technologies. After the earliest handheld flake tools emerged, shifts in hominin hand anatomy allowing for greater force during precision gripping and ease when manipulating objects in-hand are observed in the fossil record. Previous research has demonstrated how biometric traits, such as hand and digit lengths and precision grip strength, impact functional performance and ergonomic relationships when using flake and core technologies. These studies are consistent with the idea that evolutionary selective pressures would have favoured individuals better able to efficiently and effectively produce and use flaked stone tools. After the advent of composite technologies during the Middle Stone Age and Middle Palaeolithic, fossil evidence reveals differences in hand anatomy between populations, but there is minimal evidence for an increase in precision gripping capabilities. Furthermore, there is little research investigating the selective pressures, if any, impacting manual anatomy after the introduction of hafted composite stone technologies ('handles'). Here we investigated the possible influence of tool-user biometric variation on the functional performance of 420 hafted Clovis knife replicas. Our results suggest there to be no statistical relationships between biometric variables and cutting performance. Therefore, we argue that the advent of hafted stone technologies may have acted as a 'performance equaliser' within populations and removed (or reduced) selective pressures favouring forceful precision gripping capabilities, which in turn could have increased the relative importance of cultural evolutionary selective pressures in the determination of a stone tool's performance. [ABSTRACT FROM AUTHOR]

Short-term hunter-gatherer residential camps have been a central feature of human settlement patterns and social structure for most of human evolutionary history. Recent analyses of ethnohistoric hunter-gatherer data show that across different environments, the average size of hunter-gatherer bands is remarkably constant and that bands are commonly formed by a small number of coresident families. Using ethnoarchaeological data, we examine the relationship between the physical infrastructure of camps and their social organization. We compiled a dataset of 263 ethnoarchaeologically observed hunter-gatherer camps from 13 studies in the literature. We focus on both the scale of camps, or their average size, structure, and composition, and the dynamics that governed their variation. Using a combination of inferential statistics and linear models, we show that the physical infrastructure of camps, measured by the number of household features, reflects the internal social organization of hunter-gatherer bands. Using scaling analyses, we then show that the variation among individual camps is related to a predictable set of dynamics between camp area, infrastructure, the number of occupants, and residence time. Moreover, the scale and dynamics that set the statistical variance in camp sizes are similar across different environments and have important implications for reconstructing prehistoric hunter-gatherer social organization and behavior from the archaeological record. [ABSTRACT FROM AUTHOR]

European expansion and contact with indigenous populations led to catastrophic depopulation primarily through the introduction of novel infectious diseases to which native peoples had limited exposure and immunity. In the Amazon Basin such contacts continue to occur with more than 50 isolated indigenous societies likely to make further contacts with the outside world in the near future. Ethnohistorical accounts are useful for quantifying trends in the severity and frequency of epidemics through time and may provide insight into the likely demographic consequences of future contacts. Here we compile information for 117 epidemics that affected 59 different indigenous societies in Greater Amazonia and caused over 11,000 deaths between 1875 and 2008, mostly (75%) from measles, influenza, and malaria. Results show that mortality rates from epidemics decline exponentially through time and, independently, with time since peaceful contact. The frequency of documented epidemics also decreases with time since contact. While previous work on virgin soil epidemics generally emphasizes the calamity of contacts, we focus instead on improvements through time. The prospects for better survivorship during future contacts are good provided modern health care procedures are implemented immediately. [ABSTRACT FROM AUTHOR]

The authors reflect on protection of isolated societies in South America. They state government policies of Brazil and Peru, along with support by the United Nations, is to leave isolated societies alone and comments on problems with this strategy due to intermittent interaction with the outside world introducing diseases to the tribes. They recommend controlled contact with isolated tribes and the importance of sustained around-the-clock medical treatment and food.

Stone‐tipped weaponry was important for the survival of past peoples, and many functional and non‐functional factors likely influenced their design. Two functional factors that past peoples likely considered in the design of their stone tips are durability (whether or not a stone tip breaks) and robusticity (how much damage is incurred upon breakage). Many factors have been shown experimentally to influence stone tip influence durability and robusticity, including stone raw material. Here, we further explore the relationship between stone raw material and stone tip durability and robusticity via controlled experiments comparing chert and obsidian. We first demonstrate with semi‐static fracture strength analyses that obsidian stone tips require less force to break than do chert stone tips. We then show with dynamic ballistics impact testing that obsidian stone tips are less durable and robust than chert stone tips. Our results are entirely consistent with previous experimental comparisons of chert versus obsidian stone tips, and support the hypothesis that past peoples, when presented with multiple raw materials, likely weighed their costs and benefits in the process of selection. [ABSTRACT FROM AUTHOR]

Stone that fractured conchoidally was an important resource for prehistoric hunter‐gatherers. In recent years, archaeologists have come to realize that rather than defining stone "quality" simply and implicitly as "high" or "low," a stone's quality can be best defined in several different explicit and often quantitative ways involving production, function, or social benefits. Here, we examine the stone quality—defined as "fracture predictability"—of Upper Mercer chert when it is locally versus nonlocally acquired by prehistoric people in Ohio, USA. By quantitatively assessing silicon dioxide (SiO2) content and loss on ignition, we compared stone tools from a site at the Upper Mercer outcrop (n = 42) to those found at archaeological sites over 100 km north of it (n = 126). Our results showed that the former on average were of significantly higher quality than the latter. We conclude with a consideration of factors that could cause this difference in quality, suggesting that the lower quality of Upper Mercer chert in northern Ohio might be explained by northern people's decreased familiarity with it during the Archaic period and by their decreased access to it during the Woodland and Late Precontact periods. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Genealogies contain information on the prevalence of different sibling types that result from past reproductive behavior. Full sibling sets stem from stable monogamy, paternal half siblings primarily indicate male reproductive skew, and maternal half siblings reflect unstable pair bonds. Methods Full and half sibling types are calculated for a total of 61,181 siblings from published genealogies for 80 small-scale societies, including foragers, horticulturalists, agriculturalists, and pastoralists from around the world. Results Most siblings are full (61%) followed by paternal half siblings (27%) and maternal half siblings (13%). Paternal half siblings are positively correlated with more polygynous marriages, higher at low latitudes, and slightly higher in nonforagers, Maternal half sibling fractions are slightly higher at low latitudes but do not vary with subsistence. Partible paternity societies in Amazonia have more paternal half siblings indicating higher male reproductive skew. Conclusions Sibling counts from genealogies provide a convenient method to simultaneously investigate the reproductive skew and pair-bond stability dimensions of human mating systems cross-culturally. Am. J. Hum. Biol. 28:335-342, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The south coast of South Africa provides the earliest evidence for Middle Stone Age (MSA) coastal resource exploitation by early Homo sapiens . In coastal archaeology worldwide, there has been a debate over the general productivity of intertidal foraging, leading to studies that directly measure productivity in some regions, but there have been no such studies in South Africa. Here we present energetic return rate estimates for intertidal foraging along the southern coast of South Africa from Blombos Cave to Pinnacle Point. Foraging experiments were conducted with Khoi-San descendants of the region, and hourly caloric return rates for experienced foragers were measured on 41 days near low tide and through three seasons over two study years. On-site return rates varied as a function of sex, tidal level, marine habitat type and weather conditions. The overall energetic return rate from the entire sample (1492 kcal h −1 ) equals or exceeds intertidal returns reported from other hunter-gatherer studies, as well as measured return rates for activities as diverse as hunting mammals and plant collecting. Returns are projected to be exceptionally high (∼3400 kcal h −1 for men, ∼1900 kcal h −1 for women) under the best combination of conditions. However, because of the monthly tidal cycle, high return foraging is only possible for about 10 days per month and for only 2–3 h on those days. These experiments suggest that while intertidal resources are attractive, women and children could not have subsisted independently, nor met all their protein-lipid needs from marine resources alone, and would have required substantial additional energy and nutrients from plant gathering and/or from males contributing game. [ABSTRACT FROM AUTHOR]

Human societies share a large number of complex social traits relating to kinship, which together constitute what is called here the human kinship configuration. I use a comparative phylogenetic approach to show that each of the traits making up that configuration has an evolutionary history and hence a biological foundation. The origin of many complex traits may be explained in terms of emergent products of the combination of more elementary features present in other primate species, whereas other traits appear to emerge from the combination of primate features with uniquely human cognitive abilities. The resulting composite traits thus have a compounded biological foundation, but at the same time they are always manifest under specific cultural--formal and semantic--expressions in any society. The traits may thus be seen as open-ended, culturally polymorphic and polysemous categories, or sociocultural categories, with the categories themselves having a biological foundation while their contents are culturally defined. Importantly, those categories need not be cross-culturally universal even though they are natural; their presence or absence in a given society is culturally modulated. I argue that a large number of such categories operate as an interface that helps bridge the gap between human biology and the sociocultural realm and that information on that interface is required for understanding how human nature structures cultural diversity. [ABSTRACT FROM AUTHOR]

Hypotheses on the benefits of the practice of partible paternity are tested using demographic data for Ache foragers of Paraguay. Partible paternity refers to the institution of multiple males considered to contribute to the conception of a single offspring. Analyses focus on patterns of primary and secondary co-fatherhood among men, genealogical relationships between co-fathers, and relation between band co-residence and co-fatherhood. Results indicate that men who had more secondary fatherhood also had more primary fatherhood; co-fathers are more closely related, on average, than men who are not co-fathers; and co-fathers were also more likely to reside together than men who were not co-fathers, even after controlling for relatedness. Results are most consistent with women choosing co-fathers of offspring in ways that maximize likelihood and amount of investment (multiple investors hypothesis) and men competing for more mates with at least partially affiliative outcomes (mate competition and male alliance hypotheses). [ABSTRACT FROM AUTHOR]