Mortality,fertility, and the OY ratio in a model hunter–gatherer system

An agent‐based model (ABM) is used to explore how the ratio of old to young adults (the OY ratio) in a sample of dead individuals is related to aspects of mortality, fertility, and longevity experienced by the living population from which the sample was drawn. The ABM features representations of rules, behaviors, and constraints that affect person‐ and household‐level decisions about marriage, reproduction, and infant mortality in hunter–gatherer systems. The demographic characteristics of the larger model system emerge through human‐level interactions playing out in the context of “global” parameters that can be adjusted to produce a range of mortality and fertility conditions. Model data show a relationship between the OY ratios of living populations (the living OY ratio) and assemblages of dead individuals drawn from those populations (the dead OY ratio) that is consistent with that from empirically known ethnographic hunter–gatherer cases. The dead OY ratio is clearly related to the mean ages, mean adult mortality rates, and mean total fertility rates experienced by living populations in the model. Sample size exerts a strong effect on the accuracy with which the calculated dead OY ratio reflects the actual dead OY ratio of the complete assemblage. These results demonstrate that the dead OY ratio is a potentially useful metric for paleodemographic analysis of changes in mortality and mean age, and suggest that, in general, hunter–gatherer populations with higher mortality, higher fertility, and lower mean ages are characterized by lower dead OY ratios. Am J Phys Anthropol 154:222–231, 2014. © 2014 Wiley Periodicals, Inc.     

Evolution of the Ainu Language in Space and Time

Languages evolve over space and time. Illuminating the evolutionary history of language is important because it provides a unique opportunity to shed light on the population history of the speakers. Spatial and temporal aspects of language evolution are particularly crucial for understanding demographic history, as they allow us to identify when and where the languages originated, as well as how they spread across the globe. Here we apply Bayesian phylogeographic methods to reconstruct spatiotemporal evolution of the Ainu language: an endangered language spoken by an indigenous group that once thrived in northern Japan. The conventional dual-structure model has long argued that modern Ainu are direct descendants of a single, Pleistocene human lineage from Southeast Asia, namely the Jomon people. In contrast, recent evidence from archaeological, anthropological and genetic evidence suggest that the Ainu are an outcome of significant genetic and cultural contributions from Siberian hunter-gatherers, the Okhotsk, who migrated into northern Hokkaido around 900–1600 years ago. Estimating from 19 Ainu language varieties preserved five decades ago, our analysis shows that they are descendants of a common ancestor who spread from northern Hokkaido around 1300 years ago. In addition to several lines of emerging evidence, our phylogeographic analysis strongly supports the hypothesis that recent expansion of the Okhotsk to northern Hokkaido had a profound impact on the origins of the Ainu people and their culture, and hence calls for a refinement to the dual-structure model.     

Biogeochemical inferences of mobility of early Holocene fisher‐foragers from the Southern Sahara Desert

North Africa is increasingly seen as an important context for understanding modern human evolution and reconstructing biocultural adaptations. The Sahara, in particular, witnessed a fluorescence of hunter‐gatherer settlement at the onset of the Holocene after an extended occupational hiatus. Subsequent subsistence changes through the Holocene are contrary to those documented in other areas where mobile foraging gave way to settled agricultural village life. In North Africa, extractive fishing and hunting was supplanted by cattle and caprine pastoralism under deteriorating climatic conditions. Therefore, the initial stage of food production in North Africa witnessed a likely increase in mobility. However, there are few studies of paleomobility in Early Holocene hunter‐gatherer Saharan populations and the degree of mobility is generally assumed. Here, we present radiogenic strontium isotope ratios from Early Holocene fisher‐forager peoples from the site of Gobero, central Niger, southern Sahara Desert. Data indicate a relatively homogeneous radiogenic strontium isotope signature for this hunter‐gather population with limited variability exhibited throughout the life course or among different individuals. Although the overall signature was local, some variation in the radiogenic strontium isotope data likely reflects transhumance into the nearby Aïr Massif. Data from Gobero were significantly less variable than in other worldwide hunter‐gatherer populations, including those thought to be fairly sedentary. Strontium data from Gobero were also significantly different from contemporaneous sites in southwestern Libya. These patterns are discussed with respect to archaeological models of community organization and technological evolution. Am J Phys Anthropol 2011. © 2011 Wiley‐Liss, Inc.     

Deep History of East Asian Populations Revealed Through Genetic Analysis of the Ainu

Despite recent advances in population genomics, much remains to be elucidated with regard to East Asian population history. The Ainu, a hunter–gatherer population of northern Japan and Sakhalin island of Russia, are thought to be key to elucidating the prehistory of Japan and the peopling of East Asia. Here, we study the genetic relationship of the Ainu with other East Asian and Siberian populations outside the Japanese archipelago using genome-wide genotyping data. We find that the Ainu represent a deep branch of East Asian diversity more basal than all present-day East Asian farmers. However, we did not find a genetic connection between the Ainu and populations of the Tibetan plateau, rejecting their long-held hypothetical connection based on Y chromosome data. Unlike all other East Asian populations investigated, the Ainu have a closer genetic relationship with northeast Siberians than with central Siberians, suggesting ancient connections among populations around the Sea of Okhotsk. We also detect a recent genetic contribution of the Ainu to nearby populations, but no evidence for reciprocal recent gene flow is observed. Whole genome sequencing of contemporary and ancient Ainu individuals will be helpful to understand the details of the deep history of East Asians.     

Craniometric variation of the Ainu: an assessment of differential gene flow from northeast Asia into northern Japan, Hokkaido

In and after the latest Neolithic period in Japan (approximately B.P. 2,300 years), there were two distinct waves of migration from eastern Asia. One is well known as successive episodes in which indigenous inhabitants of main-island Japan were intruded on by new arrivals with advanced technology, and of a different genetic stock. Another migration of people and culture, identified as the Okhotsk culture, reached the northeastern part of Hokkaido. As opposed to main-island Japan, the morphological continuity from the Neolithic to recent inhabitants in Hokkaido (Ainu) is notable, so that the evidence of admixture easily could have escaped notice. In this study, the effects of gene flow from an outside source on the pattern of among-group variation of Hokkaido Ainu are examined by means of two models. One is the R-matrix model comparing observed and expected craniometric variation for estimating differential external gene flow into a region. The other is a simple simulation model that estimates admixture in a population with two parental populations. The two approaches give similar results. The results suggest the possibility of admixture between the migrants from Northeast Asia, the Okhotsk culture people, and the indigenous inhabitants in Hokkaido during the 5th to 12th centuries A.D., at least in northeastern Hokkaido. Such gene flow may have a certain degree of effect on the genetic structure of recent Ainu. The findings further suggest morphological heterogeneity in Northeast Asia during the Holocene that has relevance for understanding the morphological heterogeneity seen through time in the New World.     

Infant feeding practice in medieval Japan: Stable carbon and nitrogen isotope analysis of human skeletons from Yuigahama‐minami

A longer breastfeeding duration provides various positive effects in subadult health because of abundant immunological factors and nutrients in human breast milk, and decreases the natural fertility of a population through lactational amenorrhea. In this study, we measured stable carbon and nitrogen isotope ratios in the bone collagen of three adults and 45 subadults from the Yuigahama‐minami site (from 12th to 14th century) in Kamakura, the early medieval capital of Japan. Marine foods, C₃‐based terrestrial foods, and freshwater fish are the primarily protein sources for adults. The changes in the nitrogen isotope ratios of subadults suggest that the relative dietary protein contribution from breast milk started to decrease from 1.1 years of age and ended at 3.8 years. The age at the end of weaning in the Yuigahama‐minami population was greater than that in the typical non‐industrial populations, a premodern population in the Edo period Japan, and medieval populations in the UK. Skeletons of townspeople from medieval Kamakura indicate severe nutritional stress (e.g., enamel hypoplasia and cribra orbitalia), yet this longer duration of breastfeeding did not compensate adverse effects for nutritional deficiency. The longer breastfeeding period may have been a consequence of complementary food shortage and bad health of subadults. Kamakura experienced urbanization and population increase in the early medieval period. The younger age‐at‐death distribution and high nutritional stresses in the Yuigahama‐minami population and later weaning, which is closely associated with longer inter‐birth interval for mothers, suggests that Kamakura developed and increased its population by immigration during urbanization. Am J Phys Anthropol 156:241–251, 2015. © 2014 Wiley Periodicals, Inc.     

HLA class II alleles in Ainu living in Hidaka district,Hokkaido, northern Japan

The Ainu people are considered to be the descendants of preagricultural native populations of northern Japan, while the majority of the population of contemporary Japan (Wajin) is descended mainly from postneolithic migrants. Polymorphisms of the HLA-DRB1, DRB3, and DQB1 alleles were investigated in DNA samples of 50 Ainu living in Hidaka district, Hokkaido. Unique features of the Ainu in this study were high incidences of DRB1*1401, DRB1*1406, and a newly described allele, DRB1*1106 (20%, 17%, and 5%, respectively). On the other hand, several common alleles in Wajin (DRB1*1502, 1302, 0803, and 1501) were found at relatively low frequencies (1–2%) in Ainu. Previously DRB1*1406 was described as a characteristic allele of some Native American or northeast Asian ethnic groups, and DRB1*1106 had been found in only two Singapore Chinese and one Korean. Principal component analysis of various populations based on HLA class II allele frequencies places the Ainu population midway between other east Asian populations, including Wajin, and Native Americans. These observations may support the hypothesis that the Ainu people are the descendants of some Upper Paleolithic populations of northeast Asia from which Native Americans are also descended. © 1996 Wiley-Liss, Inc.     

Introducing fecal stable isotope analysis in primate weaning studies

This research investigates the potential of a new, noninvasive method for determining age of weaning among primates using stable carbon and nitrogen isotope ratios in feces. Analysis of stable isotope ratios in body tissues is a well‐established method in archeology and ecology for reconstructing diet. This is the first study to investigate weaning in primates using fecal stable isotope ratios. Diets of a single François’ langur (Trachypithecus francoisi) mother–infant pair at the Toledo Zoo are reconstructed using this technique to track changes in infant suckling behavior over the weaning period. Stable isotope ratios in feces are sampled instead of more traditional samples such as bone or hair to enable daily, noninvasive snapshots of weaning status. Isotopic assessments of weaning status are compared to visual assessments to identify any discordance between the two. Three measurements documented the transition from breast milk to solid foods: stable carbon isotope ratios (δ¹³C), stable nitrogen isotope ratios (δ¹⁵N), and nitrogen content of feces (%N). It appears that solid foods were introduced at approximately 2 months of infant age, but that nursing continued into the 12th month, when sample collection ceased. Stable isotope data exposed a much longer weaning period than what was expected based on previously published data for captive langurs, and clarified visual estimates of weaning status. This reflects the method's sensitivity to suckling at night and ability to distinguish actual nursing from comfort nursing. After testing this method with zoo animals, it can readily be applied among wild populations. An isotopic approach to weaning provides a new, accurate, and biologically meaningful assessment of interbirth intervals, and facilitates a better understanding of mother–infant interactions. Both of these outcomes are critical for developing successful conservation strategies for captive and wild primates. Am. J. Primatol. 74:926‐939, 2012. © 2012 Wiley Periodicals, Inc.     

The population characteristics and trophic status of herring in the pelagic layer of the northern Okhotsk Sea

The trophic status of Okhotsk and Gizhiga-Kamchatka herring populations is defined more accurately through the analysis of their diet and ratios of stable nitrogen and carbon isotopes based on materials of trawl catches in the Sea of Okhotsk for the period from 2003 to 2010. The possibility of applying isotope analysis to the study of the stock characteristics of herring in the northern Sea of Okhotsk is evaluated.     

Variation of sterility and fertility in Utricularia australis f. australis in Hokkaido, northern Japan

Seed-production ability was studied in Utricularia australis R. Br. f. australis Komiya and Shibata through field observation, pollination experiment, pollen culture, and isozyme analysis for populations in various regions of Hokkaido, northern Japan. Utricularia australis f. australis has previously been postulated to be sterile in Japan, however, in the present study, fertile populations were found in eastern Hokkaido. Bisexual sterility and male sterility were suspected to be present in populations in the western part of Hokkaido. There was also a strain that seemed to produce no seed because of intra-clonal inbreeding depression or self-incompatibility. Isozyme analysis of three enzyme systems indicated a uniformity of multienzymatic phenotype (MEP) in each population or region. The MEP grouping of populations corresponded to the type of sterility and fertility revealed by pollination and pollen culture experiments. These experiments suggested that each regional strain had its own sterility or fertility type.     

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.     

Demographic variance in heterogeneous populations: matrix models and sensitivity analysis

The demographic consequences of stochasticity in processes such as survival and reproduction are modulated by the heterogeneity within the population. Therefore, to study effects of stochasticity on population growth and extinction risk, it is critical to use structured population models in which the most important sources of heterogeneity (e.g. age, size, developmental stage) are incorporated as i‐state variables. Demographic stochasticity in heterogeneous populations has often been studied using one of two approaches: multitype branching processes and diffusion approximations. Here, we link these approaches, through the demographic stochasticity in age‐ or stage‐structured matrix population models. We derive the demographic variance, σ²_d, which measures the per capita contribution to the variance in population growth increment, and we show how it can be decomposed into contributions from transition probabilities and fertility across ages or stages. Furthermore, using matrix calculus we derive the sensitivity of σ²_d to age‐ or stage‐specific mortality and fertility. We apply the methods to an extensive set of data from age‐classified human populations (long‐term time‐series for Sweden, Japan and the Netherlands; two hunter–gatherer populations, and the high‐fertility Hutterites), and to a size‐classified population of the herbaceous plant Calathea ovandensis. For the human populations our analysis reveals substantial temporal changes in the demographic variance as well as its main components across age. These new methods provide a powerful approach for calculating the demographic variance for any structured model, and for analyzing its main components and sensitivities. This will make possible new analyses of demographic variance across different kinds of heterogeneity in different life cycles, which will in turn improve our understanding of mechanisms underpinning extinction risk and other important biological outcomes.     

The cranial morphology of the Botocudo Indians,Brazil

The Botocudo Indians were hunter‐gatherer groups that occupied the East‐Central regions of Brazil decimated during the colonial period in the country. During the 19th century, craniometric studies suggested that the Botocudo resembled more the Paleoamerican population of Lagoa Santa than typical Native Americans groups. These results suggest that the Botocudo Indians might represent a population that retained the biological characteristics of early groups of the continent, remaining largely isolated from groups that gave origin to the modern Native South American variation. Moreover, recently, some of the Botocudo remains have been shown to have mitochondrial and autosomal DNA lineages currently found in Polynesian populations. Here, we explore the morphological affinities of Botocudo skulls within a worldwide context. Distinct multivariate analyses based on 32 craniometric variables show that 1) the two individuals with Polynesian DNA sequences have morphological characteristics that fall within the Polynesian and Botocudo variation, making their assignation as Native American specimens problematic, and 2) there are high morphological affinities between Botocudo, Early Americans, and the Polynesian series of Easter Island, which support the early observations that the Botocudo can be seen as retaining the Paleoamerican morphology, particularly when the neurocranium is considered. Although these results do not elucidate the origin of the Polynesian DNA lineages among the Botocudo, they support the hypothesis that the Botocudo represent a case of late survival of ancient Paleoamerican populations, retaining the morphological characteristics of ancestral Late Pleistocene populations from Asia. Am J Phys Anthropol 157:202–216, 2015. © 2015 Wiley Periodicals, Inc.     

Polymorphism of red cell glutamic-pyruvic transaminase in Japanese: gene frequencies in samples from Northern Japan.

The genetic polymorphism of red cell GPT was investigated by starch-gel electrophoresis in four samples from northern Japan including a sample of the Ainu of Hokkaido. The distribution of the Gpt1 gene frequencies among 10 samples excluding the Ainu so far examined showed heterogeneity. The geographical cline of Gpt1 gene frequency reported in southern Japan was not observed in northern Japan.     

Weaning at Anglo‐Saxon raunds: Implications for changing breastfeeding practice in britain over two millennia

This study investigated stable‐isotope ratio evidence of weaning for the late Anglo‐Saxon population of Raunds Furnells, Northamptonshire, UK. δ¹⁵N and δ¹³C values in rib collagen were obtained for individuals of different ages to assess the weaning age of infants within the population. A peak in δ¹⁵N values at about 2‐year‐old, followed by a decline in δ¹⁵N values until age three, indicates a change in diet at that age. This change in nitrogen isotope ratios corresponds with the mortality profile from the site, as well as with archaeological and documentary evidence on attitudes towards juveniles in the Anglo‐Saxon period. The pattern of δ¹³C values was less clear. Comparison of the predicted age of weaning to published data from sites dating from the Iron Age to the 19th century in Britain reveals a pattern of changing weaning practices over time, with increasingly earlier commencement and shorter periods of complementary feeding in more recent periods. Such a change has implications for the interpretation of socioeconomic changes during this period of British history, since earlier weaning is associated with decreased birth spacing, and could thus have contributed to population growth. Am J Phys Anthropol 151:604–612, 2013. © 2013 Wiley Periodicals, Inc.     

Archaeoentomological study of a pre-Columbian funerary bundle (mortuary cave of Candelaria,Coahuila, Mexico)

The archaeoentomological study of insect remains recovered from a pre-Columbian funerary bundle (10th–11th centuries ad) is presented and illustrated. Among this material, 12 species belonging to 10 families and four distinct orders have been identified. From the biological data of the different taxa, some hypotheses about the funerary practices of the hunter–gatherer semi nomads of Northern Mexico are proposed.     

Quantitative Reconstruction of Weaning Ages in Archaeological Human Populations Using Bone Collagen Nitrogen Isotope Ratios and Approximate Bayesian Computation

BackgroundNitrogen isotope analysis of bone collagen has been used to reconstruct the breastfeeding practices of archaeological human populations. However, weaning ages have been estimated subjectively because of a lack of both information on subadult bone collagen turnover rates and appropriate analytical models.MethodologyTemporal changes in human subadult bone collagen turnover rates were estimated from data on tissue-level bone metabolism reported in previous studies. A model for reconstructing precise weaning ages was then developed using a framework of approximate Bayesian computation and incorporating the estimated turnover rates. The model is presented as a new open source R package, WARN (Weaning Age Reconstruction with Nitrogen isotope analysis), which computes the age at the start and end of weaning, ¹⁵N-enrichment through maternal to infant tissue, and value of collagen synthesized entirely from weaning foods with their posterior probabilities. The model was applied to 39 previously reported Holocene skeletal populations from around the world, and the results were compared with weaning ages observed in ethnographic studies.ConclusionsThere were no significant differences in the age at the end of weaning between the archaeological (2.80±1.32 years) and ethnographic populations. By comparing archaeological populations, it appears that weaning ages did not differ with the type of subsistence practiced (i.e., hunting–gathering or not). Most of -enrichment (2.44±0.90‰) was consistent with biologically valid values. The nitrogen isotope ratios of subadults after the weaning process were lower than those of adults in most of the archaeological populations (−0.48±0.61‰), and this depletion was greater in non-hunter–gatherer populations. Our results suggest that the breastfeeding period in humans had already been shortened by the early Holocene compared with those in extant great apes.     

The origins of food production in north China: A different kind of agricultural revolution

By roughly 8,000 calendar years before the present (calBP), hunter‐gatherers across a broad swath of north China had begun small‐scale farming of broomcorn millet (Panicum miliaceum) and foxtail millet (Setaria italica). 1 - 6 According to traditional wisdom, this early millet farming evolved from the intensive hunter‐gatherer adaptation represented by the late Pleistocene microblade tradition of northern China, 2 , 7 termed here the North China Microlithic. The archeological record of this hunter‐gatherer connection is poorly documented, however, and as a result the early agricultural revolution in north China is not as well understood as those that occurred in other parts of the world. The Laoguantai site of Dadiwan, in the western Loess Plateau, Gansu Province, PRC, furnishes the first complete record of this transition, which unfolded quite differently from other, better known, agricultural revolutions.     

Habitat,Climate, and Fisher and Marten Distributions

Since the mid-twentieth century, fisher populations (Pekania pennanti) increased in several eastern jurisdictions of North America, particularly in the northern part of the species’ range. Changes in fisher distribution have led to increased overlap with the southern portion of the range of American marten (Martes americana), whose populations may be locally declining. This overlap occurs particularly in habitats undergoing natural and anthropogenic modification. The objective of our study was to determine the respective effects of habitat changes and climatic conditions on fisher and marten populations in Quebec, Canada, based on trapper knowledge. We analyzed annual fisher and marten harvest (number of pelts sold/100 km²) between the 1984–1985 and 2014–2015 trapping seasons using linear mixed models. Fisher harvest increased with the increased abundance of mixed forests >12 m tall, resulting from decades of forest harvesting. Fisher harvest decreased with increasing spring rains, which can affect survival when rearing young. Marten harvest decreased with increasing winter rains, which lower thermoregulation capacity and hamper movements by creating an ice crust on the snowpack, reducing access to subnivean areas. Decline in marten harvest during the 30-year study period coincided with an increase in fisher harvest, suggesting possible interspecific competition. Results highlight that managers should strive to maintain mixedwood stands taller than 12 m to maintain high quality habitat for fishers. Our study confirms the importance of working with trappers to assess furbearing population trends in response to habitat changes and climatic conditions. © 2019 The Wildlife Society.