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1.
Science ; 382(6666): 53-58, 2023 10 06.
Artículo en Inglés | MEDLINE | ID: mdl-37797024

RESUMEN

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.


Asunto(s)
ADN Antiguo , Demografía , Salud , Estructura Social , Humanos , África , Américas , Asia , Oceanía , Demografía/historia , Salud/historia
2.
PLoS Genet ; 19(9): e1010931, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37676865

RESUMEN

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.


Asunto(s)
Pueblo Africano , Demografía , Filogenia , Polimorfismo de Nucleótido Simple , Animales , Humanos , Población Negra/genética , Mapeo Cromosómico , Genotipo , Hombre de Neandertal/genética , Polimorfismo de Nucleótido Simple/genética , Pueblo Africano/genética , Demografía/historia , Variación Biológica Poblacional/genética , Modelos Estadísticos , Sesgo
3.
Sci Rep ; 12(1): 733, 2022 01 14.
Artículo en Inglés | MEDLINE | ID: mdl-35031610

RESUMEN

Since prehistoric times, southern Central Asia has been at the crossroads of the movement of people, culture, and goods. Today, the Central Asian populations are divided into two cultural and linguistic groups: the Indo-Iranian and the Turko-Mongolian groups. Previous genetic studies unveiled that migrations from East Asia contributed to the spread of Turko-Mongolian populations in Central Asia and the partial replacement of the Indo-Iranian populations. However, little is known about the origin of the latters. To shed light on this, we compare the genetic data on two current-day Indo-Iranian populations - Yaghnobis and Tajiks - with genome-wide data from published ancient individuals. The present Indo-Iranian populations from Central Asia display a strong genetic continuity with Iron Age samples from Turkmenistan and Tajikistan. We model Yaghnobis as a mixture of 93% Iron Age individual from Turkmenistan and 7% from Baikal. For the Tajiks, we observe a higher Baikal ancestry and an additional admixture event with a South Asian population. Our results, therefore, suggest that in addition to a complex history, Central Asia shows a remarkable genetic continuity since the Iron Age, with only limited gene flow.


Asunto(s)
Demografía/historia , Flujo Génico/genética , Genética de Población , Migración Humana/historia , Lenguaje , Asia Central , Pueblo Asiatico/genética , Cultura , Historia Antigua , Humanos
4.
PLoS One ; 16(3): e0247647, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33651801

RESUMEN

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.


Asunto(s)
Algoritmos , Demografía/historia , Genética de Población , Genoma Humano , Cadenas de Markov , Modelos Genéticos , Pueblo Asiatico , Teorema de Bayes , Simulación por Computador , Variación Genética , Historia del Siglo XXI , Historia Antigua , Historia Medieval , Humanos , Linaje , Densidad de Población , Población Blanca
5.
Popul Health Metr ; 19(Suppl 1): 8, 2021 02 08.
Artículo en Inglés | MEDLINE | ID: mdl-33557845

RESUMEN

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.


Asunto(s)
Demografía/historia , Muerte Perinatal , Mortinato , Encuestas y Cuestionarios , Composición Familiar , Femenino , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Lactante , Mortalidad Infantil , Recién Nacido , Embarazo , Estudios Retrospectivos , Mortinato/epidemiología
6.
Rev. bras. estud. popul ; 38: e0170, 2021. graf
Artículo en Portugués | LILACS | ID: biblio-1341118

RESUMEN

Na sequência da integração europeia, os fluxos migratórios portugueses foram diminuindo, de tal forma que, na viragem do século, acreditou-se que Portugal tinha passado de "país de emigrantes" para "país de imigrantes". Com efeito, nas últimas décadas do século XX, Portugal atraiu inclusive cidadãos do país que, tradicionalmente, recebeu as mais significativas levas de expatriados portugueses (o Brasil) e, no contexto global, passou a integrar o conjunto de países atrativos para os migrantes económicos. Não obstante, a recente crise económica que pautou os primeiros anos do século XXI veio pôr a descoberto que essa realidade não estava solidificada, pelo menos não tanto como alguns cientistas sociais defenderam. Isto porque novos fluxos migratórios emergiram no território nacional, particularmente visíveis em áreas de baixa densidade, como é o caso da maior parte do distrito da Guarda. Neste trabalho, tendo como pano de fundo a região da Guarda, procuram-se equacionar "as molas impulsionadoras" que estão, novamente, a impelir estes portugueses a procurarem melhores condições de vida longe do país, na tentativa de perceber até que ponto estes novos fluxos migratórios têm uma génese comum aos que os precederam ou se, pelo contrário, têm configurações particulares que os individualizam no panorama migratório português.


As a result of European integration, Portuguese migratory flows decreased in such a way that, at the turn of the century, it was believed that Portugal had gone from being a "country of emigrants" to "country of immigrants". Indeed, in the last decades of the twentieth century, Portugal even attracted citizens of the country which traditionally received the most significant waves of Portuguese expatriates (Brazil) and, in the global context, became part of the set of countries attractive to economic migrants. However, the recent economic crisis that marked the first years of the 21st century has revealed this reality was not consolidated, at least not as much as some social scientists have argued. This is because new migratory flows have emerged in the national territory, particularly visible in low density territories as is the case in most of the district of Guarda. In this work, with the Guarda region as a backdrop, we seek to equate "the driving springs" that are, once again, impelling these Portuguese to seek better living conditions away from the country, in an attempt to understand the extent to which these new migratory flows have a common genesis to those who preceded them or, whether, on the contrary, they have particular configurations that individualize them in the Portuguese migratory panorama.


Como resultado de la integración europea, los flujos migratorios portugueses disminuyeron, por lo que, a principios de siglo, se creía que Portugal había pasado de ser un país de emigrantes a uno de inmigrantes. De hecho, en las últimas décadas del siglo XX, Portugal atrajo incluso a ciudadanos del país que tradicionalmente había recibido las olas más significativas de expatriados portugueses (Brasil) y, en el contexto global, se convirtió en parte del conjunto de países atractivos para los migrantes económicos. Sin embargo, la reciente crisis económica que marcó los primeros años del siglo XXI reveló que esta realidad no se ha solidificado, al menos no tanto como algunos científicos sociales han argumentado. Esto se debe a que han surgido nuevos flujos migratorios en el territorio nacional, particularmente visibles en los territorios de baja densidad, como en la mayor parte del distrito de Guarda. En este artículo, con la región de Guarda como telón de fondo, buscamos combinar los resortes impulsores que, una vez más, están llevando a estos portugueses a buscar mejores condiciones de vida fuera del país, en un intento por comprender en qué medida estos nuevos flujos de migrantes tienen una génesis común a quienes los precedieron o si, por el contrario, tienen configuraciones particulares que los individualizan en el panorama migratorio portugués.


Asunto(s)
Humanos , Migrantes , Emigrantes e Inmigrantes/historia , Portugal , Condiciones Sociales , Sociología , Trabajo , Características de la Población , Demografía/historia
8.
PLoS One ; 15(10): e0239182, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33112860

RESUMEN

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.


Asunto(s)
Especies en Peligro de Extinción , Phascolarctidae , Animales , Infecciones por Chlamydia/veterinaria , Conservación de los Recursos Naturales/historia , Conservación de los Recursos Naturales/tendencias , Demografía/historia , Demografía/tendencias , Ecosistema , Especies en Peligro de Extinción/tendencias , Femenino , Historia del Siglo XX , Historia del Siglo XXI , Masculino , Nueva Gales del Sur , Phascolarctidae/microbiología , Pronóstico , Estudios Retrospectivos
9.
Hum Biol ; 91(4): 279-296, 2020 08 06.
Artículo en Inglés | MEDLINE | ID: mdl-32767897

RESUMEN

Bayesian methods have been adopted by anthropologists for their utility in resolving complex questions about human history based on genetic data. The main advantages of Bayesian methods include simple model comparison, presenting results as a summary of probability distributions, and the explicit inclusion of prior information into analyses. In the field of anthropological genetics, for example, implementing Bayesian skyline plots and approximate Bayesian computation is becoming ubiquitous as means to analyze genetic data for the purpose of demographic or historic inference. Correspondingly, there is a critical need for better understanding of the underlying assumptions, proper applications, and limitations of these two methods by the larger anthropological community. Here we review Bayesian skyline plots and approximate Bayesian computation as applied to human demography and provide examples of the application of these methods to anthropological research questions. We also review the two core components of Bayesian demographic analysis: the coalescent and Bayesian inference. Our goal is to describe their basic mechanics in an attempt to demystify them.


Asunto(s)
Antropología/métodos , Teorema de Bayes , Demografía/historia , Genética de Población/instrumentación , Simulación por Computador , Demografía/estadística & datos numéricos , Historia Antigua , Humanos , Linaje , Filogenia , Dinámica Poblacional/historia , Probabilidad
10.
Rev Assoc Med Bras (1992) ; 66(2): 194-200, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32428155

RESUMEN

OBJECTIVE: To describe the current distribution and historical evolution of undergraduate courses in medicine in Brasil. METHODS: Analytical cross-sectional study of secondary data. Through the Ministry of Education, the data of the medical courses were obtained, and through the Brazilian Institute of Geography and Statistics, the population and economic data of the Brazilian states were obtained. RESULTS: In Brasil, there were 298 medical courses (1,42 courses / million inhabitants) in January 2018, totaling 31,126 vacancies per year, with 9,217 gratuitous vacancies (29.6%) and 17,963 vacancies in the hinterland (57, 7%). In Brazilian states, there are positive and statistically significant (p <0.001) correlations of the variables: "vacancies" and "population" (R 0.92); "vacancies" and "gross domestic product" ("GDP") (R 0.83); "percentage of vacancies in the hinterland" and "population in the hinterland" (R 0.71) and "percentage of vacancies in the hinterland" and "GDP" (R 0.64). There was a negative and statistically significant correlation between "gratuitous vacancy percentage" and "GDP" (R -0.54, p = 0.003). More paid courses than gratuitous courses and more courses in the hinterland than in the capitals have been created since 1964, in proportions that have remained similar since then, but in higher numbers since 2002. CONCLUSIONS: The distribution of medical courses in Brasil correlates with the population and economical production of each state. The expansion of Brazilian medical education, which has been accelerated since 2002, is based mainly on paid courses in the hinterland, in the same pattern since 1964.


Asunto(s)
Educación de Pregrado en Medicina/historia , Educación de Pregrado en Medicina/estadística & datos numéricos , Facultades de Medicina/historia , Facultades de Medicina/estadística & datos numéricos , Brasil , Estudios Transversales , Demografía/historia , Demografía/estadística & datos numéricos , Geografía , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Humanos
12.
Sci Rep ; 10(1): 5096, 2020 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-32198446

RESUMEN

Historical data can clarify ecological attributes of fauna in sites that have subsequently been altered by anthropogenic activities. We used the 1960s notebooks of pioneering East African naturalist C.J.P. Ionides to extract quantitative information on captures of 484 snakes of five species (rhinoceros vipers Bitis nasicornis, black mambas Dendroaspis polylepis, Jameson's mambas D. jamesoni, water cobras Naja annulata, and eastern forest cobras N. subfulva). High capture rates suggest high abundances of all species. The relative numbers of each species collected changed over the years and differed seasonally, reflecting targeting by Ionides. Sex ratios and age-class distributions differed among species and were affected by factors such as month of collection and time of day. Habitat use was affected by species, sex and body size: for example, arboreality became less common with increasing body size in the rhinoceros viper and black mamba, and males were found in arboreal sites more often than were females. In both D. jamesoni and D. polylepis, adult males and females were recorded together in September-October, suggesting reproductive activity at this time of year. Although fragmentary, the data from Ionides' notebooks provide a unique glimpse into ecological patterns of snakes within an African landscape half a century ago.


Asunto(s)
Demografía/historia , Dendroaspis/clasificación , Naja/clasificación , Viperidae/clasificación , África Oriental , Animales , Conservación de los Recursos Naturales , Ecosistema , Femenino , Historia del Siglo XX , Masculino , Razón de Masculinidad
13.
PLoS One ; 15(2): e0229363, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32092129

RESUMEN

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.


Asunto(s)
Arqueología , Composición Familiar , Vivienda , Matrimonio , Filogenia , Antropología , Demografía/historia , Composición Familiar/historia , Femenino , Historia Antigua , Vivienda/historia , Humanos , Masculino , Matrimonio/historia , Dinámica Poblacional/historia , Características de la Residencia/historia
14.
Rev. Assoc. Med. Bras. (1992) ; 66(2): 194-200, Feb. 2020. tab, graf
Artículo en Inglés | Sec. Est. Saúde SP, LILACS | ID: biblio-1136176

RESUMEN

SUMMARY BACKGROUND To describe the current distribution and historical evolution of undergraduate courses in medicine in Brasil. METHODS Analytical cross-sectional study of secondary data. Through the Ministry of Education, the data of the medical courses were obtained, and through the Brazilian Institute of Geography and Statistics, the population and economic data of the Brazilian states were obtained. RESULTS In Brasil, there were 298 medical courses (1,42 courses / million inhabitants) in January 2018, totaling 31,126 vacancies per year, with 9,217 gratuitous vacancies (29.6%) and 17,963 vacancies in the hinterland (57, 7%). In Brazilian states, there are positive and statistically significant (p <0.001) correlations of the variables: "vacancies" and "population" (R 0.92); "vacancies" and "gross domestic product" ("GDP") (R 0.83); "percentage of vacancies in the hinterland" and "population in the hinterland" (R 0.71) and "percentage of vacancies in the hinterland" and "GDP" (R 0.64). There was a negative and statistically significant correlation between "gratuitous vacancy percentage" and "GDP" (R -0.54, p = 0.003). More paid courses than gratuitous courses and more courses in the hinterland than in the capitals have been created since 1964, in proportions that have remained similar since then, but in higher numbers since 2002. CONCLUSIONS The distribution of medical courses in Brasil correlates with the population and economical production of each state. The expansion of Brazilian medical education, which has been accelerated since 2002, is based mainly on paid courses in the hinterland, in the same pattern since 1964.


RESUMO OBJETIVO Descrever a distribuição e evolução histórica das vagas em cursos de graduação em medicina no Brasil. MÉTODOS Estudo transversal analítico de dados secundários. No Ministério da Educação obtiveram-se dados dos cursos de medicina e no Instituto Brasileiro de Geografia e Estatística foram obtidos dados populacionais e econômicos dos estados. RESULTADOS Havia no Brasil, até janeiro de 2018, 298 cursos de medicina (1,42 curso/milhão de habitantes), totalizando 31.126 vagas anuais, com 9.217 vagas gratuitas (29,6%) e 17.963 vagas no interior do País (57,7%). Nos estados há correlações positivas e significativas (p<0,001) das variáveis: "vagas em medicina" e "população" (R 0,92); "vagas em medicina" e "produto interno bruto" ("PIB") (R 0,83); "percentual de vagas em medicina no interior" e "população no interior" (R 0,71) e "percentual de vagas em medicina no interior" e "PIB" (R 0,64). Há correlação negativa e significativa entre "percentual de vagas gratuitas" e "PIB" (R -0,54, p=0,003). Passaram a ser criados mais cursos pagos do que gratuitos e mais cursos no interior do que nas capitais a partir de 1964 (p <0,001), e a relação curso/milhão de habitantes aumentou a partir de 2002 (p<0,001). CONCLUSÕES A distribuição de vagas em cursos de medicina no Brasil correlaciona-se à população e à produção econômica de cada estado. A expansão do ensino médico brasileiro, acelerada além do crescimento populacional a partir de 2002, é baseada principalmente em cursos pagos no interior dos estados brasileiros, característica inalterada desde 1964.


Asunto(s)
Humanos , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Facultades de Medicina/historia , Facultades de Medicina/estadística & datos numéricos , Educación de Pregrado en Medicina/historia , Educación de Pregrado en Medicina/estadística & datos numéricos , Brasil , Demografía/historia , Demografía/estadística & datos numéricos , Estudios Transversales , Geografía
15.
Early Hum Dev ; 140: 104857, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31495458

RESUMEN

This paper reviews the classical theories that attempted to explain the influences on the sex ratio at birth (M/F). These included notions pertaining to the four elements (earth, air, fire and water) and to laterality i.e. from which side of the body (in both parents) the conceptual principle arose. This narrative will also outline the initial physical measurements of male and female births and speculations by John Graunt (1620-1674), John Arbuthnott (1667-1735) and Johann Süssmilch (1707-1767), as well as the conundrums that M/F presented to Charles Darwin (1809-1882) and the theories of Ronald Fisher (1890-1962) who expanded on concepts first promulgated by Nicolas de Caritat, Marquis de Condorcet (1743-1794). Fortunately, the thousands of papers generated on topic, especially the more recent work pertaining to direct and measurable influences (such as exogenous stress periconceptually and during pregnancy) have begun to yield some concrete findings, indeed, "among this welter of evidence, it is possible to pin down a few facts" such that "we have found ourselves following Ariadne's thread to a series of clues that bind the calculation of the proportion of boys and girls at birth".


Asunto(s)
Demografía/historia , Historia del Siglo XVI , Historia del Siglo XVII , Historia del Siglo XVIII , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Historia Antigua
16.
Demography ; 56(4): 1495-1518, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31270779

RESUMEN

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.


Asunto(s)
Tasa de Natalidad/tendencias , Demografía/historia , Abuelos , Grupos Raciales/historia , Factores de Edad , Simulación por Computador , Femenino , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Relaciones Intergeneracionales , Masculino , Grupos Raciales/estadística & datos numéricos , Factores Sexuales , Estados Unidos
17.
Sci Rep ; 7(1): 15251, 2017 11 10.
Artículo en Inglés | MEDLINE | ID: mdl-29127307

RESUMEN

The transition from hunter-gatherer-fisher groups to agrarian societies is arguably the most significant change in human prehistory. In the European plain there is evidence for fully developed agrarian societies by 7,500 cal. yr BP, yet a well-established agrarian society does not appear in the north until 6,000 cal. yr BP for unknown reasons. Here we show a sudden increase in summer temperature at 6,000 cal. yr BP in northern Europe using a well-dated, high resolution record of sea surface temperature (SST) from the Baltic Sea. This temperature rise resulted in hypoxic conditions across the entire Baltic sea as revealed by multiple sedimentary records and supported by marine ecosystem modeling. Comparison with summed probability distributions of radiocarbon dates from archaeological sites indicate that this temperature rise coincided with both the introduction of farming, and a dramatic population increase. The evidence supports the hypothesis that the boundary of farming rapidly extended north at 6,000 cal. yr BP because terrestrial conditions in a previously marginal region improved.


Asunto(s)
Agricultura/historia , Arqueología , Cambio Climático/historia , Demografía/historia , Estaciones del Año , Europa (Continente) , Historia Antigua , Humanos
18.
Philos Trans R Soc Lond B Biol Sci ; 372(1729)2017 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-28760757

RESUMEN

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'.


Asunto(s)
Fertilidad , Longevidad , Reproducción , Razón de Masculinidad , Adulto , Factores de Edad , Demografía/historia , Femenino , Historia del Siglo XIX , Humanos , Masculino , Utah
19.
Sci Rep ; 7(1): 9163, 2017 08 22.
Artículo en Inglés | MEDLINE | ID: mdl-28831145

RESUMEN

Ailanthus altissima (Mill.) Swingle and its variant A. altissima var. Qiantouchun are notorious invasive weeds. Two weevils, Eucryptorrhynchus scrobiculatus (ESC) and E. brandti (EBR) are considered as candidates for biological control of A. altissima. The aim of this study was to model the potential distributions of ESC and EBR using CLIMEX 4.0. The projected potential distributions of ESC and EBR included almost all current distribution areas of A. altissima, except Southeast Asia. Under historical climate, potential distribution area of EBR is larger than that of ESC, 46.67 × 106 km2 and 35.65 × 106 km2, respectively. For both ESC and EBR, climate change expanded the northern boundary of potential distributions northward approximately 600 km by the middle of 21st century, and 1000 km by the end of 21st century under RCP 8.5. However, the suitable range decreased to the south in the Southern Hemisphere because of heat stress. The modelled potential distributions of ESC and EBR in the United States demonstrated that the climate was suitable for both weevils. Therefore, considering only climate suitability, both ESC and EBR can be considered as potential biological control agents against A. altissima with some confidence that climatic conditions are likely suitable.


Asunto(s)
Ailanthus/crecimiento & desarrollo , Control de Malezas/métodos , Gorgojos/crecimiento & desarrollo , Ailanthus/efectos de los fármacos , Animales , Asia , Agentes de Control Biológico/farmacología , Cambio Climático , Demografía/historia , Historia del Siglo XXI , Calor , Modelos Teóricos
20.
Med Sci (Paris) ; 33(3): 355-362, 2017 Mar.
Artículo en Francés | MEDLINE | ID: mdl-28367827

RESUMEN

Life expectancy curves for several nations provide an astonishingly precise image of the major events that occurred during the last century, highlight similarities between France and Great Britain, and reflect the tremendous economic hardship associated with the end of the Soviet Union.


Asunto(s)
Demografía , Desastres , Esperanza de Vida/tendencias , Demografía/historia , Desastres/historia , Desastres/estadística & datos numéricos , Francia/epidemiología , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Esperanza de Vida/historia , Federación de Rusia/epidemiología , Reino Unido/epidemiología
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