Going local with ancient DNA: A review of human histories from regional perspectives

Ancient DNA (aDNA) has added a wealth of information about our species' history, including insights on genetic origins, migrations and gene flow, genetic admixture, and health and disease. Much early work has focused on continental-level questions, leaving many regional questions, especially those relevant to the Global South, comparatively underexplored. A few success stories of aDNA studies from smaller laboratories involve more local aspects of human histories and health in the Americas, Africa, Asia, and Oceania. In this Review, we cover some of these contributions by synthesizing finer-scale questions of importance to the archaeogenetics field, as well as to Indigenous and Descendant communities. We further highlight the potential of aDNA to uncover past histories in regions where colonialism has neglected the oral histories of oppressed peoples.

Modeling of African population history using f-statistics is biased when applying all previously proposed SNP ascertainment schemes

f-statistics have emerged as a first line of analysis for making inferences about demographic history from genome-wide data. Not only are they guaranteed to allow robust tests of the fits of proposed models of population history to data when analyzing full genome sequencing data-that is, all single nucleotide polymorphisms (SNPs) in the individuals being analyzed-but they are also guaranteed to allow robust tests of models for SNPs ascertained as polymorphic in a population that is an outgroup in a phylogenetic sense to all groups being analyzed. True "outgroup ascertainment" is in practice impossible in humans because our species has arisen from a substructured ancestral population that does not descend from a homogeneous ancestral population going back many hundreds of thousands of years into the past. However, initial studies suggested that non-outgroup-ascertainment schemes might produce robust enough results using f-statistics, and that motivated widespread fitting of models to data using non-outgroup-ascertained SNP panels such as the "Affymetrix Human Origins array" which has been genotyped on thousands of modern individuals from hundreds of populations, or the "1240k" in-solution enrichment reagent which has been the source of about 70% of published genome-wide data for ancient humans. In this study, we show that while analyses of population history using such panels work well for studies of relationships among non-African populations and one African outgroup, when co-modeling more than one sub-Saharan African and/or archaic human groups (Neanderthals and Denisovans), fitting of f-statistics to such SNP sets is expected to frequently lead to false rejection of true demographic histories, and failure to reject incorrect models. Analyzing panels of SNPs polymorphic in archaic humans, which has been suggested as a solution for the ascertainment problem, has limited statistical power and retains important biases. However, by carrying out simulations of diverse demographic histories, we show that bias in inferences based on f-statistics can be minimized by ascertaining on variants common in a union of diverse African groups; such ascertainment retains high statistical power while allowing co-analysis of archaic and modern groups.

Demographic inference from multiple whole genomes using a particle filter for continuous Markov jump processes

Demographic events shape a population's genetic diversity, a process described by the coalescent-with-recombination model that relates demography and genetics by an unobserved sequence of genealogies along the genome. As the space of genealogies over genomes is large and complex, inference under this model is challenging. Formulating the coalescent-with-recombination model as a continuous-time and -space Markov jump process, we develop a particle filter for such processes, and use waypoints that under appropriate conditions allow the problem to be reduced to the discrete-time case. To improve inference, we generalise the Auxiliary Particle Filter for discrete-time models, and use Variational Bayes to model the uncertainty in parameter estimates for rare events, avoiding biases seen with Expectation Maximization. Using real and simulated genomes, we show that past population sizes can be accurately inferred over a larger range of epochs than was previously possible, opening the possibility of jointly analyzing multiple genomes under complex demographic models. Code is available at https://github.com/luntergroup/smcsmc.

Four decades of measuring stillbirths and neonatal deaths in Demographic and Health Surveys: historical review

BACKGROUND

Worldwide, an estimated 5.1 million stillbirths and neonatal deaths occur annually, 98% in low- and middle-income countries. Limited coverage of civil and vital registration systems necessitates reliance on women's retrospective reporting in household surveys for data on these deaths. The predominant platform, Demographic and Health Surveys (DHS), has evolved over the last 35 years and differs by country, yet no previous study has described these differences and the effects of these changes on stillbirth and neonatal death measurement.

METHODS

We undertook a review of DHS model questionnaires, protocols and methodological reports from DHS-I to DHS-VII, focusing on the collection of information on stillbirth and neonatal deaths describing differences in approaches, questionnaires and geographic reach up to December 9, 2019. We analysed the resultant data, applied previously used data quality criteria including ratios of stillbirth rate (SBR) to neonatal mortality rate (NMR) and early NMR (ENMR) to NMR, comparing by country, over time and by DHS module.

RESULTS

DHS has conducted >320 surveys in 90 countries since 1984. Two types of maternity history have been used: full birth history (FBH) and full pregnancy history (FPH). A FBH collecting information only on live births has been included in all model questionnaires to date, with data on stillbirths collected through a reproductive calendar (DHS II-VI) or using additional questions on non-live births (DHS-VII). FPH collecting information on all pregnancies including live births, miscarriages, abortions and stillbirths has been used in 17 countries. We found no evidence of variation in stillbirth data quality assessed by SBR:NMR over time for FBH surveys with reproductive calendar, some variation for surveys with FBH in DHS-VII and most variation among the surveys conducted with a FPH. ENMR:NMR ratio increased over time, which may reflect changes in data quality or real epidemiological change.

CONCLUSION

DHS remains the major data source for pregnancy outcomes worldwide. Although the DHS model questionnaire has evolved over the last three and half decades, more robust evidence is required concerning optimal methods to obtain accurate data on stillbirths and neonatal deaths through household surveys and also to develop and test standardised data quality criteria.

A 29-year retrospective analysis of koala rescues in New South Wales, Australia

The koala (Phascolarctos cinereus) is currently listed by both the IUCN and the Australian Governments' Threatened Species Scientific Committee as vulnerable to extinction with an overall decreasing population trend. It is unknown exactly how many koalas remain in the wild, but it is known that habitat fragmentation and bushfires have ultimately contributed to the decline of the koala all over Australia. This novel study is a retrospective analysis of data over a 29-year period (1989-2018) using records for 12,543 sightings and clinical care admissions for wild koalas from the major koala hot-spots (Port Stephens, port Macquarie and Lismore) in New South Wales, Australia. This study aims to understand the long-term patterns and trends of key stressors that are contributing to the decline of koalas in New South Wales, and the synergic interactions of factors such as rescue location, sex and age of the koala, and if their decline is influenced progressively by year. The main findings of this retrospective analysis indicated that between all 3 rescue sites, the most common prognosis was disease, the most common disease was signs of chlamydia, and the most common outcome was release. The location where the highest number of koalas were found prior to being reported as sighted or admitted into clinical care was within the regional area of Lismore. Furthermore, sex was not a discriminating factor when it came to prognosis or outcome, but age was significant. Finally, incidents of disease were found to increase over long-term, whereas release decreased over time and euthanasia increased. The wealth of data available to us and the retrospective analysis enabled us in a way to 'zoom out' and reveal how the key environmental stressors have fluctuated spatially and temporally. In conclusion, our data provides strong evidence of added pressures of increased human population growth in metropolitan zones, which increases risks of acute environmental trauma and proximate stressors such as vehicle collisions and dog-attacks as well as increased sightings of virtually healthy koalas found in exposed environments. Thus our 'zoom out' approach provides support that there is an urgent need to strengthen on-ground management, bushfire control regimes, environmental planning and governmental policy actions that should hopefully reduce the proximate environmental stressors in a step wise approach. This will ensure that in the next decade (beyond 2020), NSW koalas will hopefully start to show reversed trends and patterns in exposure to environmental trauma and disease, and population numbers will return towards recovery and stability.

Identifying post-marital residence patterns in prehistory: A phylogenetic comparative analysis of dwelling size

Post-marital residence patterns are an important aspect of human social organization. However, identifying such patterns in prehistoric societies is challenging since they leave almost no direct traces in archaeological records. Cross-cultural researchers have attempted to identify correlates of post-marital residence through the statistical analysis of ethnographic data. Several studies have demonstrated that, in agricultural societies, large dwellings (over ca. 65 m²) are associated with matrilocality (spouse resides with or near the wife’s family), whereas smaller dwellings are associated with patrilocality (spouse resides with or near the husband’s family). In the present study, we tested the association between post-marital residence and dwelling size (average house floor area) using phylogenetic comparative methods and a global sample of 86 pre-industrial societies, 22 of which were matrilocal. Our analysis included the presence of agriculture, sedentism, and durability of house construction material as additional explanatory variables. The results confirm a strong association between matrilocality and dwelling size, although very large dwellings (over ca. 200 m²) were found to be associated with all types of post-marital residence. The best model combined dwelling size, post-marital residence pattern, and sedentism, the latter being the single best predictor of house size. The effect of agriculture on dwelling size becomes insignificant once the fixity of settlement is taken into account. Our results indicate that post-marital residence and house size evolve in a correlated fashion, namely that matrilocality is a predictable response to an increase in dwelling size. As such, we suggest that reliable inferences about the social organization of prehistoric societies can be made from archaeological records.

A Cohort Perspective on the Demography of Grandparenthood: Past, Present, and Future Changes in Race and Sex Disparities in the United States

How has the demography of grandparenthood changed over the last century? How have racial inequalities in grandparenthood changed, and how are they expected to change in the future? Massive improvements in mortality, increasing childlessness, and fertility postponement have profoundly altered the likelihood that people become grandparents as well as the timing and length of grandparenthood for those that do. The demography of grandparenthood is important to understand for those taking a multigenerational perspective of stratification and racial inequality because these processes define the onset and duration of intergenerational relationships in ways that constrain the forms and levels of intergenerational transfers that can occur within them. In this article, we discuss four measures of the demography of grandparenthood and use simulated data to estimate the broad contours of historical changes in the demography of grandparenthood in the United States for the 1880-1960 birth cohorts. Then we examine race and sex differences in grandparenthood in the past and present, which reveal declining inequality in the demography of grandparenthood and a projection of increasing group convergence in the coming decades.

Causes and consequences of adult sex ratio imbalance in a historical U.S. population

The responsiveness of individuals to partner availability has been well-documented across the literature. However, there is disagreement regarding the direction of the consequences of sex ratio imbalance. Specifically, does an excess of males or females promote male-male mating competition? In an attempt to clarify the role of the adult sex ratio (ASR) on behaviour, here we evaluate both competing and complimentary expectations derived from theory across the social and biological sciences. We use data drawn from a historical, nineteenth century population in North America and target several life-history traits thought to be affected by partner availability: age at first birth, relationship status, completed fertility and longevity. Furthermore, we assess the role of various contributors to a population's ASR. We find that both the contributors to and consequences of sex ratio imbalance vary over time. Our results largely support predictions of greater male pairbond commitment and lesser male mating effort, as well as elevated bargaining power of women in response to female scarcity. After reviewing our findings, and others from across the literature, we highlight the need to adjust predictions in response to ASR imbalance by the: (i) culturally mediated mating arena, (ii) variable role of demographic inputs across time and place, (iii) constraints to behavioural outcomes across populations, and (iv) ability and accuracy of individuals to assess partner availability.This article is part of the themed issue 'Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies'.

Clinical prediction and the idea of a population

Using an analysis of the British Medical Journal over the past 170 years, this article describes how changes in the idea of a population have informed new technologies of medical prediction. These approaches have largely replaced older ideas of clinical prognosis based on understanding the natural histories of the underlying pathologies. The 19^th-century idea of a population, which provided a denominator for medical events such as births and deaths, was constrained in its predictive power by its method of enumerating individual bodies. During the 20^th century, populations were increasingly constructed through inferential techniques based on patient groups and samples seen to possess variable characteristics. The emergence of these new virtual populations created the conditions for the emergence of predictive algorithms that are used to foretell our medical futures.

GIS-based landform classification of Bronze Age archaeological sites on Crete Island

Various physical attributes of the Earth's surface are factors that influence local topography and indirectly influence human behaviour in terms of habitation locations. The determination of geomorphological setting plays an important role in archaeological landscape research. Several landform types can be distinguished by characteristic geomorphic attributes that portray the landscape surrounding a settlement and influence its ability to sustain a population. Geomorphometric landform information, derived from digital elevation models (DEMs), such as the ASTER Global DEM, can provide useful insights into the processes shaping landscapes. This work examines the influence of landform classification on the settlement locations of Bronze Age (Minoan) Crete, focusing on the districts of Phaistos, Kavousi and Vrokastro. The landform classification was based on the topographic position index (TPI) and deviation from mean elevation (DEV) analysis to highlight slope steepness of various landform classes, characterizing the surrounding landscape environment of the settlements locations. The outcomes indicate no interrelationship between the settlement locations and topography during the Early Minoan period, but a significant interrelationship exists during the later Minoan periods with the presence of more organised societies. The landform classification can provide insights into factors favouring human habitation and can contribute to archaeological predictive modelling.

Genetic stratigraphy of key demographic events in Arabia

At the crossroads between Africa and Eurasia, Arabia is necessarily a melting pot, its peoples enriched by successive gene flow over the generations. Estimating the timing and impact of these multiple migrations are important steps in reconstructing the key demographic events in the human history. However, current methods based on genome-wide information identify admixture events inefficiently, tending to estimate only the more recent ages, as here in the case of admixture events across the Red Sea (∼8–37 generations for African input into Arabia, and 30–90 generations for “back-to-Africa” migrations). An mtDNA-based founder analysis, corroborated by detailed analysis of the whole-mtDNA genome, affords an alternative means by which to identify, date and quantify multiple migration events at greater time depths, across the full range of modern human history, albeit for the maternal line of descent only. In Arabia, this approach enables us to infer several major pulses of dispersal between the Near East and Arabia, most likely via the Gulf corridor. Although some relict lineages survive in Arabia from the time of the out-of-Africa dispersal, 60 ka, the major episodes in the peopling of the Peninsula took place from north to south in the Late Glacial and, to a lesser extent, the immediate post-glacial/Neolithic. Exchanges across the Red Sea were mainly due to the Arab slave trade and maritime dominance (from ∼2.5 ka to very recent times), but had already begun by the early Holocene, fuelled by the establishment of maritime networks since ∼8 ka. The main “back-to-Africa” migrations, again undetected by genome-wide dating analyses, occurred in the Late Glacial period for introductions into eastern Africa, whilst the Neolithic was more significant for migrations towards North Africa.

Evolutionary demography of agricultural expansion in preindustrial northern Finland

A shift from nomadic foraging to sedentary agriculture was a major turning point in human evolutionary history, increasing our population size and eventually leading to the development of modern societies. We however lack understanding of the changes in life histories that contributed to the increased population growth rate of agriculturalists, because comparable individual-based reproductive records of sympatric populations of agriculturalists and foragers are rarely found. Here, we compared key life-history traits and population growth rate using comprehensive data from the seventieth to nineteenth century Northern Finland: indigenous Sami were nomadic hunter-fishers and reindeer herders, whereas sympatric agricultural Finns relied predominantly on animal husbandry. We found that agriculture-based families had higher lifetime fecundity, faster birth spacing and lower maternal mortality. Furthermore, agricultural Finns had 6.2% higher annual population growth rate than traditional Sami, which was accounted by differences between the subsistence modes in age-specific fecundity but not in mortality. Our results provide, to our knowledge, the most detailed demonstration yet of the demographic changes and evolutionary benefits that resulted from agricultural revolution.

Human heredity after 1945: moving populations centre stage

The essays in this issue look at the contested history of human heredity after 1945 from a new analytical angle, that of populations and the ways in which they were constructed and studied. One consequence of this approach is that we do not limit our attention to the disciplinary study of genetics. After the Second World War, populations became a central topic for an array of fields, including demography, anthropology, epidemiology, and public health. Human heredity had a role in all of these: demographers carried out mental surveys in efforts to distinguish hereditary from environmental factors, doctors screened newborns and tested pregnant women for chromosome disorders; anthropologists collected blood from remote locations to gain insights into the evolutionary history of human populations; geneticists monitored people exposed to radiation. Through this work, populations were labelled as clinical, normal, primitive, pure, vulnerable or exotic. We ask: how were populations chosen, who qualified as members, and how was the study of human heredity shaped by technical, institutional and geopolitical conditions? By following the practical and conceptual work to define populations as objects of research, the essays trace the circulation of practices across different fields and contexts, bringing into view new actors, institutions, and geographies. By doing so the collection shows how human heredity research was linked to the broader politics of the postwar world, one profoundly conditioned by Cold War tensions, by nationalist concerns, by colonial and post-colonial struggles, by modernisation projects and by a new internationalism.

[Historical review of the distribution of Anopheles (Nyssorhynchus) darlingi (Diptera: Culicidae) in the Peruvian Amazon]

Anopheles (Nyssorhynchus) darlingi has been reported since 1931 in border areas of the department of Loreto, mainly along the borders with Brazil and Colombia. In 1994, during an outbreak of malaria, An. darlingi was found in neighboring towns to Iquitos. At present, its distribution has expanded considerably in Loreto. This paper reviews literature available for all possible information on the distribution of mosquitoes, particularly anopheline in the Amazon region of the country, with special emphasis on An darlingi. Entomological collections were also conducted in the departments of Madre de Dios and Ucayali in order to know and verify the distribution of An. darlingi. At present, the distribution of the species is confined to localities in southeastern Peru with Bolivia border towns, in a town near the Abujao River in the department of Ucayali, and widely in the northeastern region of the Amazon basin of Loreto in Peru.

Disciplining ethnicity: social sorting intersects with political demography in Israel's pre-state period

This article presents an analysis of the professional and political activities of the demographer Roberto Bachi prior to Israel's establishment as a state in 1948. The article describes his involvement in two interconnected major areas: first, his advocacy of pro-natal policies, connected to a nation-building strategy by the Jewish population to achieve numerical dominance over Arab Palestinians in areas to be incorporated in the Jewish state, and second, the development of Jewish ethnic distinctions, particularly the 'Mizrahi type', to track differences in birthrates and changing cultural features within the Jewish population. The article also revises the historical record by showing the importance of this ethnic classification in the years prior to the large waves of Jewish immigration from Arab countries. Without the reworking of the popular category 'Mizrahi' into a scientifically systematized category by a demographer who would become the head of the state's Central Bureau of Statistics upon its founding in 1948, this binary social epistemology could not be as strong and legitimate as it actually was. Two factors account for Bachi's success. First was his ability to provide a new way of understanding the present in terms of the future. His numerical predictions on the Jewish and Arab demographic development made statistics and demography an indispensable technology for public policy and social planning. Second was his role as a boundary actor--a unique mediating position between political and scientific spheres. The Israeli case study exemplifies similar dynamics found in other countries during periods of structuring the modern state, namely, processes in which experts of infrastructural knowledge such as statistics and demography saw themselves as responsible for the national progress and its social modernity.

Pagan-Christian change in northeastern Hungary in the 10th-13th centuries AD--a palaeodemographic aspect

In the present paper the authors compared skeletal populations (2421 individuals) excavated from four cemeteries, namely Hajdúdorog-Gyúlás (10th century AD), Hajdidorog-Temetöhegy (11th century AD), Hajdúdorog-Katidülö (12th-13th century AD) and Hajdúdorog-Szálldáföld (12th-13th century AD) from a micro-region of Northern Hajdúság (located in the northern part of the Great Hungarian Plain in Hungary in the Carpathian Basin) based on demographic data. The cemeteries were dated to the age of the Hungarian conquest and the Arpadian age and provided representative data for anthropological research. Previous studies based on craniological and archaeological investigations have already suggested that there was discontinuity in the population history between the 10th and the 11th centuries AD and continuity between the 11th and 12th centuries AD in this region. This hypothesis could be partially supported by demographic investigations because conclusive evidence was found that there must have been a change in the population at the turn of the 10th and 11th centuries AD, and there was certain continuity between the 11th and 12-13th centuries AD. The authors suppose that there were two crises in the examined period: the first crisis set in at the transition from the pagan era (10th century AD) to the Christian era (from the beginning of the 11th century AD, with population resettlements within the Carpathian Basin), the second might have been more moderate and meant burying the dead of the populations lacking a church in the churchyards of villages which had a church. At that time one graveyard around a church may have been used by several village populations.

Demographic histories, isolation and social factors as determinants of the genetic structure of Alpine linguistic groups

Great European mountain ranges have acted as barriers to gene flow for resident populations since prehistory and have offered a place for the settlement of small, and sometimes culturally diverse, communities. Therefore, the human groups that have settled in these areas are worth exploring as an important potential source of diversity in the genetic structure of European populations. In this study, we present new high resolution data concerning Y chromosomal variation in three distinct Alpine ethno-linguistic groups, Italian, Ladin and German. Combining unpublished and literature data on Y chromosome and mitochondrial variation, we were able to detect different genetic patterns. In fact, within and among population diversity values observed vary across linguistic groups, with German and Italian speakers at the two extremes, and seem to reflect their different demographic histories. Using simulations we inferred that the joint effect of continued genetic isolation and reduced founding group size may explain the apportionment of genetic diversity observed in all groups. Extending the analysis to other continental populations, we observed that the genetic differentiation of Ladins and German speakers from Europeans is comparable or even greater to that observed for well known outliers like Sardinian and Basques. Finally, we found that in south Tyroleans, the social practice of Geschlossener Hof, a hereditary norm which might have favored male dispersal, coincides with a significant intra-group diversity for mtDNA but not for Y chromosome, a genetic pattern which is opposite to those expected among patrilocal populations. Together with previous evidence regarding the possible effects of “local ethnicity” on the genetic structure of German speakers that have settled in the eastern Italian Alps, this finding suggests that taking socio-cultural factors into account together with geographical variables and linguistic diversity may help unveil some yet to be understood aspects of the genetic structure of European populations.

A space-for-time (SFT) substitution approach to studying historical phenological changes in urban environment

Plant phenological records are crucial for predicting plant responses to global warming. However, many historical records are either short or replete with data gaps, which pose limitations and may lead to erroneous conclusions about the direction and magnitude of change. In addition to uninterrupted monitoring, missing observations may be substituted via modeling, experimentation, or gradient analysis. Here we have developed a space-for-time (SFT) substitution method that uses spatial phenology and temperature data to fill gaps in historical records. To do this, we combined historical data for several tree species from a single location with spatial data for the same species and used linear regression and Analysis of Covariance (ANCOVA) to build complementary spring phenology models and assess improvements achieved by the approach. SFT substitution allowed increasing the sample size and developing more robust phenology models for some of the species studied. Testing models with reduced historical data size revealed thresholds at which SFT improved historical trend estimation. We conclude that under certain circumstances both the robustness of models and accuracy of phenological trends can be enhanced although some limitations and assumptions still need to be resolved. There is considerable potential for exploring SFT analyses in phenology studies, especially those conducted in urban environments and those dealing with non-linearities in phenology modeling.

Malthusian dynamics in a diverging Europe: Northern Italy, 1650-1881

Recent empirical research questions the validity of using Malthusian theory in preindustrial England. Using real wage and vital rate data for the years 1650-1881, I provide empirical estimates for a different region: Northern Italy. The empirical methodology is theoretically underpinned by a simple Malthusian model, in which population, real wages, and vital rates are determined endogenously. My findings strongly support the existence of a Malthusian economy wherein population growth decreased living standards, which in turn influenced vital rates. However, these results also demonstrate how the system is best characterized as one of weak homeostasis. Furthermore, there is no evidence of Boserupian effects given that increases in population failed to spur any sustained technological progress.

Historical effects on beta diversity and community assembly in Amazonian trees

We present a unique perspective on the role of historical processes in community assembly by synthesizing analyses of species turnover among communities with environmental data and independent, population genetic-derived estimates of among-community dispersal. We sampled floodplain and terra firme communities of the diverse tree genus Inga (Fabaceae) across a 250-km transect in Amazonian Peru and found patterns of distance-decay in compositional similarity in both habitat types. However, conventional analyses of distance-decay masked a zone of increased species turnover present in the middle of the transect. We estimated past seed dispersal among the same communities by examining geographic plastid DNA variation for eight widespread Inga species and uncovered a population genetic break in the majority of species that is geographically coincident with the zone of increased species turnover. Analyses of these and 12 additional Inga species shared between two communities located on opposite sides of the zone showed that the populations experienced divergence 42,000-612,000 y ago. Our results suggest that the observed distance decay is the result not of environmental gradients or dispersal limitation coupled with ecological drift--as conventionally interpreted under neutral ecological theory--but rather of secondary contact between historically separated communities. Thus, even at this small spatial scale, historical processes seem to significantly impact species' distributions and community assembly. Other documented zones of increased species turnover found in the western Amazon basin or elsewhere may be related to similar historical processes.

The effect of Rh-negative disease on perinatal mortality: some evidence from the Skellefteå region, Sweden, 1860-1900

The Rh-negative gene is a well-known cause of perinatal mortality. In this article, we analyze the possible role of Rh disease in perinatal mortality and stillbirths in a particular historical setting: the Skellefteå region in northern Sweden between 1860 and 1900. The data used for the study cover 23,067 children born to 4,943 women. The exact impact is not possible to establish using historical data, but the typical pattern of the disease allows us to make estimations. The expected levels based on knowledge of blood group distribution, the risk of sensitization from Rh incompatability, and the risk of perinatal mortality in births by sensitized mothers are compared with the observed levels. The results show that Rh disease was important for perinatal mortality and clustering of deaths within families.

How did women count? A note on gender-specific age heaping differences in the sixteenth to nineteenth centuries

The role of human capital in economic growth is now largely uncontested. One indicator of human capital frequently used for the pre-1900 period is age heaping, which has been increasingly used to measure gender-specific differences. In this note, we find that in some historical samples, married women heap significantly less than unmarried women. This is still true after correcting for possible selection effects. A possible explanation is that a percentage of women adapted their ages to that of their husbands, hence biasing the Whipple index. We find the same effect to a lesser extent for men. Since this bias differs over time and across countries, a consistent comparison of female age heaping should be made by focusing on unmarried women.

Reproductive behavior during the pre-transitional period: evidence from rural Bologna

A longitudinal, micro-level study of the effect of socioeconomic transformations on fertility mechanisms in the rural hinterland of Bologna between 1818 and 1900 (the beginning of the demographic transition) demonstrates that the premature death of a last-born child reduces the interval between two consecutive childbirths. Thus does it confirm the importance of breast-feeding in determining birth spacing. Women living in complex sharecropping households experienced a significantly higher risk of childbirth than did women in families headed by daily wage earners. In addition, the reproductive behavior of sharecroppers seemed to be substantially invariant to short-term ºuctuations in prices, whereas the laborers' group experienced a negative price effect. Both descriptive and multivariate analyses indicate a slight and gradual decrease in fertility levels during the period in question.

Adolescent mortality at Winchester College, 1393-1540: new evidence for medieval mortality and methodological considerations for historical demography

This article presents new data on mortality in the late medieval period, and suggests methodologies for analysing incomplete datasets. Using data collated from the records of Winchester College this study follows the lives of 2,692 individuals, and analyses adolescent mortality in the sample group for the period 1393-1540. This study of mortality among 10-18 year olds is the first of its kind to produce data for a sample of adolescents in late medieval England, and thereby contributes significant new data to our understanding of late medieval mortality. These data are placed within the context of that obtained for other medieval population samples, most notably with studies of medieval monastic groups.

A demographic explanation for the recent rise in European fertility

Between 1998 and 2008 European countries experienced the first continent-wide increase in the period total fertility rate (TFR) since the 1960s. After discussing period and cohort influences on fertility trends, we examine the role of tempo distortions of period fertility and different methods for removing them. We highlight the usefulness of a new indicator: the tempo- and parity-adjusted total fertility rate (TFRp*). This variant of the adjusted total fertility rate proposed by Bongaarts and Feeney also controls for the parity composition of the female population and provides more stable values than the indicators proposed in the past. Finally, we estimate levels and trends in tempo and parity distribution distortions in selected countries in Europe. Our analysis of period and cohort fertility indicators in the Czech Republic, Netherlands, Spain, and Sweden shows that the new adjusted measure gives a remarkable fit with the completed fertility of women in prime childbearing years in a given period, which suggests that it provides an accurate adjustment for tempo and parity composition distortions. Using an expanded dataset for ten countries, we demonstrate that adjusted fertility as measured by TFRp* remained nearly stable since the late 1990s. This finding implies that the recent upturns in the period TFR in Europe are largely explained by a decline in the pace of fertility postponement. Other tempo-adjusted fertility indicators have not indicated such a large role for the diminishing tempo effect in these TFR upturns. As countries proceed through their postponement transitions, tempo effects will decline further and eventually disappear, thus putting continued upward pressure on period fertility. However, such an upward trend may be obscured for a few years by the effects of economic recession.

Is sibling rivalry fatal?: siblings and mortality clustering

Evidence drawn from nineteenth-century Belgian population registers shows that the presence of similarly aged siblings competing for resources within a household increases the probability of death for children younger than five, even when controlling for the preceding birth interval and multiple births. Furthermore, in this period of Belgian history, such mortality tended to cluster in certain families. The findings suggest the importance of segmenting the mortality of siblings younger than five by age group, of considering the presence of siblings as a time-varying covariate, and of factoring mortality clustering into analyses.

[Demographic and epidemiological quantification in Balearic hygienism, 1850-1930]

At the end of the 19th century, social medicine promoted the use of quantification as a means to evaluate the health status of populations. In Majorca, hygienists such as the physicians Enric Fajarnés, Bernat Riera, Antoni Mayol and Emili Darder and the civil engineer Eusebi Estada sought a better understanding of health status by considering the population growth, the demographic and epidemiological profile and the influence of weather on mortality. These calculations showed that the Balearic population had a good health status in comparison to the population of mainland Spain, although less so in the international context. These results were explained by the benevolence of the insular climate, a factor that would also guarantee the success of the public health reforms proposed.

Socioeconomic marriage differentials in Australia and New Zealand

While marriage rates are relatively stable among better-educated men and women, they are rapidly declining among those with low educational attainment. This development has been recognized in the US as a new socioeconomic pattern of marriage. This article uses census data to show that socioeconomic marriage differentials are also increasing in Australia and New Zealand. These differentials have previously been noted independently of each other and of the international picture. In synthesizing the antipodean data, the article documents the new socioeconomic marriage pattern as an international phenomenon. This article further considers the extent to which the available explanations for the new marriage pattern fit the antipodean setting. In general, the factors identified as important in the North American setting are applicable to both Australia and New Zealand. In particular, the poor marriage prospects of men with low educational attainment appear to be common to these post-industrial economies with minimalist welfare states.

Toward a comprehensive demography: rethinking the research agenda on change and response

This essay drafts a new interdisciplinary agenda for research on population and development. Starting from Kingsley Davis's 1963 formulation of change and response, Davis's analytical categories are broadened to include inertia as well as change and to encompass both demographic and non-demographic responses at the micro, meso, and macro levels. On that basis the essay proposes what can be called a comprehensive demography, an approach drawing principally on micro-level methodologies like those employed in anthropological demography. Like anthropological demography, comprehensive demography questions the rationality of actors, emphasizes cultural infuences, and stops short of the postmodernist extremes of anthropology. But it also takes explicit account of higher-level social, economic, and political factors bearing on demographic behavior and outcomes. The conclusion raises some epistemological issues. Illustrative examples are offered throughout to demonstrate the feasibility of the approach, mainly referring to sub-Saharan africa and the Caribbean and often drawn from the authors' own fieldwork.

Policy experiment in Russia: cash-for-babies and fertility change

Population decline in modern day Russia is alarmingly steep: Russia loses approximately 750 thousand people each year. To combat population decline, the Russian government instituted aggressive pro-natalist policies. The paper evaluates the capacity of new policies to change women's reproductive behavior using a socio-institutionalist theoretical framework, which analyzes the gendered interaction between the states, the labor market, and family. The paper arrives to a disappointing conclusion that while efforts to improve fertility are quite aggressive, new policies do not challenge gendered hierarchies neither in public nor in private spheres, which will further depress fertility rates of Russian women.

Exploring Thailand's mortality transition with the aid of life tables

The project Thai Health-Risk Transition: A National Cohort Study seeks to better understand the health implications of modernisation and globalisation forces impacting on Thailand. As part of its "look-back" component this paper seeks, using available life tables, to document the country's post-war mortality transition. The onset of transition through mass campaigns of the late 1940s and 1950s is first discussed before attention turns to the life tables. They are predictably far from flawless, but careful analysis does permit trends that have seen around 30 years added to life expectancy to be traced, and age patterns of improved survivorship and their relation to initiatives to improve health to be examined. The broad benefits generated by mass campaigns, ongoing improvements in infant and early childhood mortality, and a phased impact of the expansion of primary health care in rural areas on adult survival prospects after the mid-1970s are demonstrated. The paper also investigates the consequences for mortality of a motorcycle-focused rapid increase in road fatalities in the late 1980s and early 1990s and the HIV/AIDS epidemic that developed after 1984.

The case of the missing girls: sex ratios in fifteenth-century Tuscany

This article addresses the apparent shortage of women in the 1427 Florentine Catasto, perhaps the most complete premodern European demographic source. It argues that the shortage exists because it was only when they entered their first marriage that Tuscan women were viewed as complete, gendered beings by their families, government officials, and society. Before marriage, a woman’s place within the household, her gender, and even her existence were liminal, at least in Tuscan documents. The result is that the ratio of men to women is more balanced for that portion of the population past the age of marriage for women. Shifting the analysis from infants and men, where it has traditionally lain, to young adult women explains the gender imbalance in the documentation and provides a deeper understanding of the ways that gender, adulthood, and identity intersected in premodern Europe.

Living same-name siblings and British historical demography

This article examines the extent to which living siblings were given identical first names. Whilst the practice of sibling name-sharing appeared to have died out in England during the eighteenth century, in northern Scotland it persisted at least until the end of the nineteenth century. Previously it has not been possible to provide quantitative evidence of this phenomenon, but an analysis of the rich census and vital registration data for the Isle of Skye reveals that this practice was widespread, with over a third of eligible families recording same-name siblings. Our results suggest that further research should focus on regional variations in sibling name-sharing and the extent to which this northern pattern occurred in other parts of Britain.

The impact of the HIV/AIDS epidemic on kinship resources for orphans in Zimbabwe

The extended family has been recognized as a major safety net for orphans in sub-Saharan Africa. However, the mortality crisis associated with HIV/AIDS may drastically reduce the availability of relatives and thus undermine traditional forms of mutual support. In this article, the microsimulator SOCSIM is used to estimate and project quantities such as the number of living uncles, aunts, siblings, and grandparents available to orphans. The model is calibrated to the setting of Zimbabwe, using data from demographic and Health Surveys and estimates and projections of demographic rates from the United Nations. The article shows that there is a lag of more than ten years between the peak in orphanhood prevalence and the peak in scarcity of grandparents for orphans. The results indicate that a generalized HIV/AIDS epidemic has a prolonged impact on children and orphans that extends well beyond the peak in mortality. A rapid increase in the number of orphans is followed by a steady reduction in the number of living grandparents for orphans. Consequently, the burden of double orphans (both of whose parents have died) is likely to shift to uncles and aunts. In Zimbabwe, the number of living uncles and aunts per double orphan decreased between 1980 and 2010, but it is expected to increase progressively during the next few decades. Changes in kinship structure have important social consequences that should be taken into account when seeking to address the lack of care for orphans.

Lethal differences: a short history of the concepts of wealth and poverty in Danish epidemiological writings, 1858-1914

Through a study of the history of the concepts of wealth and poverty, this paper investigates the onset of a tradition in the conceptual architecture of epidemiological research concerning social differences in mortality rates from 1858 to 1914. It raises the question as to what the concepts of wealth and poverty meant to those who used them and what objects of interventions the conceptual architecture surrounding the concepts enabled the researchers to create. It argues that a transition began in the late 19th century in which an important framework for the understanding of causal relations behind the mortality patterns changed and that this change in turn influenced the scope of what was conceived as relevant objects of intervention.

Yearning, learning, and conceding: reasons men and women change their childbearing intentions

People's childbearing intentions change over the course of their reproductive lives. These changes have been conceptualized as occurring in response to the realization that an individual is unlikely to achieve his or her intended fertility, because of constraints such as the "biological clock" or lack of a partner. In this article, we find that changes to child-bearing plans are influenced by a much wider range of factors than this. People change their plans in response to the wishes of their partners, in response to social norms, as the result of repartnering, and as the result of learning about the costs and benefits of parenthood; there are also differences between the factors that influence men's and women's decision-making. In a departure from existing studies in this area, we use a flexible analytical framework that enables us to analyze increases in planned fertility separately from decreases. This allows us to uncover several complexities of the decision-making process that would otherwise be hidden, and leads us to conclude that the determinants of increases in planned fertility are not simply equal and opposite to the determinants of decreases.

Marrying in the city in times of rapid urbanization

Economic, social, political, and demographic processes changed Western European cities strongly during the nineteenth century. Especially during this time, the northern part of Belgium (Flanders) became highly urbanized. Investigating the long-term development of the marriage pattern in the cities of Antwerp, Aalst, and Ghent gives a detailed picture of the evolution of the urban marriage pattern. In this article, specific emphasis is on gender, social, and migration distinctions. The results confirm that there is a male-female difference and variation among various social and migrant groups in the age at first marriage during the period 1800-1906. Moreover, regional differences are also visible. In the port city of Antwerp, massive immigration caused a unique evolution in the age at first marriage during the last decades of the nineteenth century, which did not appear in the textile cities of Aalst and Ghent during this time.

The demise of the American Indios

This symposium takes as its point of departure two books by Massimo Livi Bacci, Conquest and El Dorado in the Marshes, published in English in 2008 and 2010. Livi Bacci assesses widely varying estimates of the demographic dimensions of the collapse of the Native populations following their contact with Europeans and elucidates the proximate causes of that catastrophe. Drawing on models that combine production potential with demography, environment, and technology, Shripad Tuljapurkar discusses analogous historical experiences of the populations of Polynesia and the social transformation they entailed. David S. Reher argues that explanations of the estimated demographic dynamics need to take into account the negative fertility responses of the Indigenous population to the disruption of their traditional way of life. Focusing on the biological aspects of immunity to diseases such as smallpox, Andrew Noymer demonstrates that infectious diseases alone could not account for the Indios' population collapse. The contributions to this symposium are based on presentations at a session at the 2010 annual meeting of the Population Association of America, held in Dallas, Texas, that examined the demographic consequences of the Spanish conquest of the Caribbean region and of South America in light of the two books.