Pinniped behavior, foraging theory, and the depression of metapopulations and nondepression of a local population on the southern Northwest Coast of North America

Models derived from foraging theory suggest that high-value prey will be depressed (encounter rates will decrease) relative to low-value prey as human predation intensifies. Numerous case studies in ethnographic and zooarchaeological settings indicate depression of prey is very common. Exceptions to depression are few and have been cited as evidence of conservation and resource management. Reanalysis of pinniped and ungulate data from sites on the Oregon coast indicates that the metapopulation (entire population in the region) of otariids was depressed but a single local population of Steller sea lions exploited over a span of 600 years reached an equilibrium with human predation and was not subsequently depressed. This local population was not historically documented, and thus must have been extirpated by commercial sealing in the late nineteenth century. This singular case of prehistoric epiphenomenal conservation was an unintentional result of human predation that took advantage of the lack of escape behaviors among breeding male Steller sea lions.     

Bighorn hunting,resource depression,and rock art in the Coso Range,eastern California: a computer simulation model

The extraordinary record of prehistoric rock art depicting tens of thousands of animal images in the Coso Range of eastern California provides an opportunity to study the relationship between aboriginal hunting, forager ecology, bighorn prey population levels, and the production of rock art. We review archaeofaunal evidence that the Coso desert bighorn sheep population was strongly depleted during the Newberry era after 1500 B.C. We discuss the dating of the rock art and show a correlation between bighorn depletion and increased rock art production. These data are consistent with the arrival of Numic foragers ca. A.D. 600 who competed with the Coso Pre-Numics and eventually terminated the Coso rock art tradition. An ecological predator-prey computer simulation of the human populations (Numic and Pre-Numics), the sheep population, and the rock art “population”, demonstrates these proposed interconnections and gives a reasonable fit to the observed rock art production rate.     

Interpreting abundance indices: some zooarchaeological implications of Martu foraging

Indices of taxonomic abundance are commonly used by zooarchaeologists to examine resource intensification, overexploitation and gender-divisions in foraging labor. The original formulation of abundance indices developed a clear interpretive framework by linking the measure with foraging models from behavioral ecology. However, using the same basic tenets of behavioral ecology, archaeologists disagree about how to interpret variability in abundance index values: some suggest that high proportions of large prey remains represent higher overall foraging efficiency, while others argue the opposite. To help solve this problem, we use quantitative observational data with Martu hunters in Australia’s Western Desert to examine how foraging decisions and outcomes best predict variation in the abundance index values that result. We show that variation in the proportional remains of large to small game is best predicted by hunting bout success with larger prey and the time spent foraging for smaller prey. A declining abundance index results from decreasing hunting success with larger prey, increasing time invested in hunting smaller prey, or both; any of which result in a lower overall return rate than if large prey were acquired reliably. We also demonstrate that where large prey acquisition is stochastic, high index values are correlated positively with men’s proportional caloric contribution of large unreliable game, while low index values are correlated with women’s proportional foraging time for small reliable game. We discuss these results with reference to evidence of resource intensification and gender-specific foraging.     

Fremont Hunting and Resource Intensification in the Eastern Great Basin

Empirical tests of resource-intensification models argue for diminishing foraging efficiency among hunter–gatherers in California over the past 2000 years (Basgall, 1987,Research in Economic Anthropology9,21–52; Broughton, 1994aJournal of Archaeological Science21,501–514; 1994bJournal of Anthropological Anthropology13, 371–401). The evidence for this long-term trajectory consists of decreases in the abundance of large, high-ranked prey in archaeofaunal assemblages. This paper presents faunal data from Fremont structural sites in the eastern Great Basin and Northern Colorado Plateau as an additional empirical test of resource intensification patterns and compares them to trends in California and the American Southwest. The measure of resource efficiency used is the artiodactyl index (following Broughton, 1994ab), a tool derived from prey choice models of optimal foraging. Faunal data from Fremont structural sites argue that (1) foraging efficiency declined during the Fremont period, and (2) this decline was due to population growth.     

Declines in Mammalian Foraging Efficiency during the Late Holocene, San Francisco Bay, California

Resource intensification models that have been posited for prehistoric California predict decreases in foraging efficiency during the late Holocene, Using implications of the fine-grained prey model of optimal foraging theory, I derive an index of the efficiency of vertebrate prey choice from the relative abundances of large- and small-sized prey items. I then test the intensification models with late Holocene mammalian faunas from San Francisco Bay shellmounds. Dramatic linear decreases in the relalive frequency of artiodactyls compared to the smaller sea otters (Enhydra lutris) throughout the occupational histories of particular localities strongly support the resource intensification models. The declines in artiodactyl abundances are not correlated with late Holocene climatic indices developed for this region, with changes in the seasonal use of shellmounds, or with technological innovations. An intra- and interregionally consistent pattern in declining abundances of large mammals in environmentally distinct regions throughout California suggests that resource depression driven by human predators may be the single most important cause of the declines. These patterns have far-reaching implications concerning the long-term human role in structuring prehistoric ecosystems.     

Small prey hunting technology and zooarchaeological measures of taxonomic diversity and abundance: Ethnoarchaeological evidence from Central African forest foragers

Archaeological analyses of faunal assemblages often rely on rationale derived from the prey choice model to explain temporal and spatial changes in taxonomic measures of diversity and/or abundances. In this paper, we present analyses of ethnoarchaeological observations and bone assemblages created by Central African Bofi and Aka forest foragers which show that different small prey hunting technologies target specific suites of prey and that hunters vary their technological choice depending on their foraging goals. Analysis of ethnoarchaeological bone assemblages produced by the Bofi and Aka shows that variability in target prey can create spatially distinct, but contemporaneous, faunal assemblages with different diversity values and abundance indices. These data reveal important variation in how individuals within a contemporary human population rank prey and challenge current assumptions about the meaning of diversity and abundances measures in archaeological contexts. We argue that the use of diversity and abundance indices can obscure important intrasite variability in prehistoric foraging effort and suggest strategies that might enhance current techniques.     

Large shell middens in Lamberts Bay,South Africa: a case of hunter–gatherer resource intensification

Enormous shell middens (“megamiddens”) dating to c. 3000–2000 BP along the West Coast of South Africa were explained initially within a framework based on the Kalahari San ethnography. The overwhelming dominance of marine shell and low densities of artefacts and vertebrate remains were seen as merely the reflection of processing localities. A far more complex picture has emerged recently, with a trend of raising population densities and longer residential permanence between 3500 and 2500 BP. Successive reformulations of the foraging ecology of both marine and terrestrial prey are apparent, with isotopic values from human skeletons and quantified dietary remains showing increased marine food consumption during the megamidden period when compared to other stages. Shellfish collection shifted from a mix of limpets, whelks and black mussels before 3000 BP to the intensified collection of the later from about 2600 BP, with local impact on marine fauna becoming evident at this time. Coastal groups became also increasingly less reliant on large mobile game and more so on small territorial bovids and tortoises as from 3500 BP, with strongest emphasis on this foraging behaviour after 2700 BP. Read against palaeoenvironmental data, this reconstruction is consistent with hunter–gatherer resource intensification models world-wide.     

An Early Upper Palaeolithic Stone Tool Assemblage from Mughr El-Hamamah,Jordan: An Interim Report

Mughr el-Hamamah (Jordan) Layer B contains an Early Upper Palaeolithic stone tool assemblage dating to around 39–45 kya cal b.p. This assemblage is unusual in that it samples human forager activities around the ecotone between the Transjordanian Plateau and the palaeo-lake (Lake Lisan) that filled much of the Jordan Valley during Late Pleistocene times. This paper describes that assemblage, comparing it to other Levantine Upper Palaeolithic assemblages of equivalent antiquity. The Mughr el-Hamamah Layer B assemblage appears most similar to Early Ahmarian assemblages, but it departs from typical such assemblages in ways that may reflect local conditions’ influence on human activities carried out in and near the cave. Mughr el-Hamamah raises new questions about changes in residential mobility, off-site provisioning and foraging activity, and on-site task diversity in the Early Upper Palaeolithic period.     

Intertidal Foraging on Atolls: Prehistoric Forager Decision-Making at Ebon Atoll,Marshall Islands

Prehistoric molluscan assemblages provide insights into long-term patterns of human landscape use, environmental change, and human impacts to marine resources. The investigation of forager decision-making regarding the selection of certain mollusc taxa and/or the exploitation of particular habitats is fundamental to understanding human-environment interactions in the past, and is relevant for understanding trajectories of human impacts to the intertidal zone in coastal settings. We document variability in the collection of molluscs at two archaeological sites on Ebon Atoll, Republic of the Marshall Islands: one on a windward, intermittently occupied islet, and the other on a permanently inhabited leeward islet. All molluscan taxa were assigned to a range of habitats within a hierarchical classification scheme for intertidal marine environments. The relative abundance of taxa from each habitat was used as a proxy for forager decision-making. We report a generalized, non-selective, foraging strategy focused on gastropod taxa from the high intertidal and supratidal. These results indicate that rather than focusing intensively on select taxa, intertidal foragers targeted particular marine habitats, taking advantage of the predictable behaviors of the molluscs that inhabit them.     

The Taphonomy of Resource Intensification: Zooarchaeological Implications of Resource Scarcity Among Bofi and Aka Forest Foragers

Zooarchaeological analyses often rely on bone fragmentation, cut marks, and other taphonomic indicators to bolster interpretations of resource intensification that are based on observed changes in prey types and frequencies. While these taphonomic indicators are assumed to be good proxy measures of processing effort, this assumption is based on inadequate actualistic data and analysts often conflate one or more taphonomic indicators as manifestations of the same process. In this paper, we present zooarchaeological data from two villages occupied by Central African forest foragers with very different foraging efficiencies. These data provide the first case where known disparities in diet breadth and foraging efficiency are matched with prey assemblages and taphonomic attributes. Observational and quantitative data show differences between the villages in diet breadth and access to high-ranked prey, but specific taphonomic indicators such as cut mark distribution and intensity do not match predictions generated from models of resource intensification. We propose that linking different taphonomic processes to resource scarcity and intensification can provide powerful adjunctive information. However, because different processing outcomes may be associated with different kinds of resource intensification in response to different kinds of scarcity, we need to strengthen the validity of purported taphonomic indicators with more rigorous independent studies.     

Mobility-driven cultural transmission along the forager-collector continuum

Hunter-gatherers mobility regimes are often treated as discrete adaptive strategies. Here we present a model of forager mobility which treats collectors and foragers as two ends of a continuous spectrum. We show that a mobility regime can be situated along this spectrum by specifying the number of foraging moves a group makes before returning to its home base. The model allows us to explore the behavioural space between forager (i.e. residential mobility) and collector (logistical mobility) adaptations. We discuss the heuristic value of the model by showing how it can be used to make testable predictions about the impact of mobility strategies on archaeological measures such as occupation intensity and raw-material transportation distance. We then use the model to investigate the impact of mobility on rates of cultural transmission. We show that mobility-driven cultural transmission may be equivalent to a Poisson process and that the time it takes for a cultural behaviour to be transmitted between two mobile groups is optimized when the mobility regime is somewhere between pure forager and pure collectors adaptations. In addition, we find that rates of cultural transmission decline in a very regular way, as the inverse of the square root of the number of moves made before returning to home base. This suggests that there is a mechanistic connection between the mean-squared displacement of hunter-gatherers in space and the transmission of cultural traits.     

Should we expect large game specialization in the late Pleistocene? An optimal foraging perspective on early Paleoindian prey choice

Several recent studies employ foraging theory to model early Paleoindians as big game specialists who focused on hunting large bodied, high-return animals such as mammoths. In this paper, we evaluate the specialist model by identifying the range of handling times and encounter rates within which mammoth (Mammuthus columbi) specialization would occur. We continue by using allometric relationships between body size and population density in mammals to estimate encounter rates for mammoth and other North American species. Combining these two pieces of information allows for the construction of an optimal diet curve representative of late Pleistocene prey choice, given the inclusion of mammoth. Our results seriously question the model of early Paleoindians as megafaunal specialists and suggest that foragers should have pursued a wide array of taxa including not only mammoth, but the full range of ungulates and some smaller game as well. These results accord well with empirical data on prey choice from late Pleistocene archaeological contexts from across North America.     

Explaining prehistoric variation in the abundance of large prey: A zooarchaeological analysis of deer and rabbit hunting along the Pecho Coast of Central California

Three main hypotheses are commonly employed to explain diachronic variation in the relative abundance of remains of large terrestrial herbivores: (1) large prey populations decline as a function of anthropogenic overexploitation; (2) large prey tends to increase as a result of increasing social payoffs; and (3) proportions of large terrestrial prey are dependent on stochastic fluctuations in climate. This paper tests predictions derived from these three hypotheses through a zooarchaeological analysis of eleven temporal components from three sites on central California’s Pecho Coast. Specifically, we examine the trade-offs between hunting rabbits (Sylvilagus spp.) and deer (Odocoileus hemionus) using models derived from human behavioral ecology. The results show that foragers exploited a robust population of deer throughout most of the Holocene, only doing otherwise during periods associated with climatic trends unfavorable to larger herbivores. The most recent component (Late Prehistoric/Contact era) shows modest evidence of localized resource depression and perhaps greater social benefits from hunting larger prey; we suggest that these final changes resulted from the introduction of bow and arrow technology. Overall, results suggest that along central California’s Pecho Coast, density independent factors described as climatically-mediated prey choice best predict changes in the relative abundance of large terrestrial herbivores through the Holocene.     

Logistical mobility reduces subsistence risk in hunting economies

Increasing carnivory is frequently cited as one of the key trajectories in the course of hominin evolution, yet the ethnographic record demonstrates that hunting is a high-variance, risky strategy necessitating a fundamental re-organisation of the foraging pattern. Hunter-gatherers rely on intra-band sharing of hunted resources as well as inter-band insurance mechanisms to mitigate against the risk of resource failure. It is suggested that logistical mobility functions to increase encounter rates with both prey and representatives of neighbouring groups, and is thus a fundamental part of the hunting adaptation. Implementation of an ideal gas model of encounter rate demonstrates that, when logistical mobility is regarded as a basic group fission pattern, it increases encounter rates for all groups relying on greater than 34% hunting. This equates to a shift in the optimal hunting percentage, as defined by encounter rates, from 24% under residential mobility to 35% under a logistical mobility strategy. These results are discussed in relation to fission–fusion social systems in primates and social carnivores, with a view to highlighting the specific aspects in which these differ from human foraging strategies.     

人口流动对边境地区人口安全的影响及机制分析

本文关注我国边境人口变动和人口流动状况,着重分析了人口流动对边境人口安全的影响机制,并探讨了边境人口流动的影响因素。研究发现,①边境县域人口总体规模稳中略降,人口增速和增量持续减少;②人口净流出已逐步成为边境人口变动主要因素;③边境人口变动与流动影响程度有明显区域差异。外流风险型地区已出现明显的人口负增长和外流,人口安全缺乏数量和质量保障;相对稳定型地区人口保持低速增长,但其人口净流出水平正不断提高,有向外流风险型转变的趋势;相对封闭增长型地区人口增长较快,但流动性较弱。各类边境地区人口流出流入呈现不同特征,并受到经济、教育、城镇化、民族、政策等不同因素影响。     

Stable state conditions of population-dependent migration models under a zero natural growth rate

The author "attempts to examine the stable conditions of regional population under a zero natural growth rate in the context of a certain general class of [population-dependent] nonlinear migration models." Theorems regarding the stable state conditions of the migration models are presented. The parameters of the gravity migration model are then estimated empirically using data on Japanese inter-prefectural migration flows in 1966, 1970, and 1975. The possibility of achieving the stable state in Japan is discussed     

Neolithic subsistence patterns in northern Borneo reconstructed with stable carbon isotopes of enamel

The Neolithic period in island Southeast Asia is characterized by various population movements, technological innovations, and the introduction/adoption of agricultural foodstuffs. Human subsistence trends during this period, however, are poorly understood. Broad spectrum foraging is generally assumed for prehistoric groups utilizing rain forest food resources but the degree to which cultigens were part of the dietary repertoire remains unclear. This paper explores human subsistence patterns at three penecontemporaneous Neolithic sites in Sarawak (East Malaysia) using stable isotope ratios of carbon and oxygen derived from tooth enamel apatite. The sites (Niah Cave, Lubang Angin, and Gua Sireh) differ in local ecology and cultural circumstance but all are situated in C₃-dominant lowland primary rain forest. Significant differences in δ¹³C values between sites likely reflect the canopy effect and variations in foraging pattern. Lower values at Lubang Angin suggest dependence upon closed forest foraging. Higher values at Neolithic Niah Cave and Gua Sireh suggest more open forest horticulture and subsistence, including some form of systematic food production, collection, and/or habitat modification.     

Opportunistic versus target mode: Prey choice changes in central-western Korean prehistory

Human decision-making processes are usually hierarchical in that higher-level decisions impose constraints on lower-level decisions. As a result, prey choices during individual foraging trips are governed to a large degree by higher-level decisions regarding how to supply resources to satisfy demands, with higher-level decisions typically made prior to foraging trips. Resource selectivity and search bias sometimes take place in this context. By dividing resource procurement modes into opportunistic and target, I discuss how choice of mode on the basis of an overall economic plan affects prey choice during foraging trips and faunal assemblage composition resulting from those trips. An analysis of taxonomic diversity in shellmidden assemblages from the central-western Korean Late Chulmun Period (3500–1300 BC) and Middle and Late Mumun Period (700–100 BC) shows that Late Chulmun people adopted a target mode, while Middle/Late Mumun people adopted an opportunistic mode in their exploitation of marine resources. A decrease in the importance of marine resource in Middle/Late Mumun produced a change in taxonomic diversity by increasing the opportunistic cost of marine resource exploitation.     

Paleoethology as a tool for the development of archaeological models of land-use: the Crimean Middle Palaeolithic

The principal aim of our research is to capitalize on the close relationship between prehistoric hunters and prey to develop spatial models for the investigation of land-use patterns. Ideally, these models should be useful both as predictive tools for designing regional archaeological surveys, and as analytical tools for studying the distribution of known archaeological sites. Here, we build upon a basic G.I.S. model (including standard environmental variables such as slope, aspect and distance to water) adding a paleoethological variable in the form of range reconstructions for the regionally dominant, prehistoric human prey species: Equus hydruntinus.     

The prey as patch model: optimal handling of resources with diminishing returns

Foraging theory provides archaeology with a valuable set of tools for investigating the constraints that influenced procurement decisions of the past. The prey-choice model has been used extensively by archaeologists, but has significant limitations given the nature of archaeological data. This paper suggests that the seldom-used Marginal Value Theorem (MVT) is a valuable tool for examining the ecological constraints on foraging decisions and merits further archaeological application. Ethnoarchaeological and experimental cases are presented demonstrating how patch–gains curves can be generated from quantitative data on butchering return rates and handling times. Results indicate that such curves are diminishing return functions. This provides a basis for examining the linkage between processing intensity and resource fluctuation. This model allows archaeologists to address the relationship between attribute-states of faunal remains and predicted optimal post-acquisition decisions. The MVT is valuable to ethnoarchaeology because it identifies how mean foraging return rate influences the handling of acquired prey and makes quantified predictions of return rate based on processing intensity. The MVT can also be applied to archaeological studies of foraging behavior and processing intensity as it can be used to estimate the set of environmental constraints in which a given kill was made (e.g., “good” vs. “bad” times). This approach may also identify the degree to which certain currencies, such as fat, are optimized at the expense of others, such as total caloric intake.