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PubMed1998

An alternative method for assessing early mortality in contemporary populations.

Biological anthropologists are interested in a population's early mortality rates for a variety of reasons. Early mortality (infant or juvenile) is of obvious importance to those interested in demography, but early mortality statistics are useful for life history analysis, paleodemography, and human adaptability studies, among others. In general, the form of mortality statistics is derived from demography, where chronological age is the gold standard for statistical calculation and comparison. However, there are numerous problems associated with the collection, analysis, and interpretation of early mortality statistics based on age, particularly for anthropological research, which is often conducted in small or non-calendrical-age numerate populations. The infant mortality rate (IMR), for example, is notoriously difficult to determine in populations where accurate accounting of age is not routine, and yet it is widely used in demography, public health, medicine, and social science research. Here we offer an alternative to age-based early mortality statistics that makes use of human biologists' interest in, and skill at, assessing human growth and development. Our proposal is to use developmental stages of juveniles instead of relying exclusively on age as the basis for mortality statistics. Death or survival according to a developmental stage (such as crawling or weaning) may provide more accurate data that are also more closely related to the cause of death. Developmental stages have the added advantage of putting infants and children back at the center of the discussion of early mortality by focusing on their activities in relation to their environment. A case study from the Turkana population of Kenya illustrates the use of developmental stages in describing early mortality.

Cause of Death↗
PubMed2002

A brief history of R0 and a recipe for its calculation.

In this paper I present the genesis of R0 in demography, ecology and epidemiology, from embryo to its current adult form. I argue on why it has taken so long for the concept to mature in epidemiology when there were ample opportunities for cross-fertilisation from demography and ecology from where it reached adulthood fifty years earlier. Today, R0 is a more fully developed adult in epidemiology than in demography. In the final section I give an algorithm for its calculation in heterogeneous populations.

Animals↗
PubMed1989

[Some problems of intensification of studies on population self-reproduction].

"The paper deals with the most important debatable problems of theoretical demography. It is stated that modern demography is not a harmonious scientific system but a conglomeration of the data on different aspects of the population and its reproduction....A conclusion is made that a number of important problems in modern demography cannot be solved when approaching the given population as [a] human population." (SUMMARY IN ENG)

Demography↗
PubMed2004

Geographic variation of caste structure among ant populations.

Morphologically distinct worker castes of eusocial insects specialize in different tasks. The relative proportions of these castes and their body sizes represent the demography of a colony that is predicted to vary adaptively with environments. Despite strong theoretical foundations, there has been little empirical evidence for the evolution of colony demography in nature. We show that geographically distinct populations of the ant Pheidole morrisi differ in worker caste ratios and worker body sizes in a manner consistent with microevolutionary divergence. We further show that the developmental mechanism for caste determination accounts for the unique pattern of covariation observed in these two traits. Behavioral data reveal that the frequency of different tasks performed by workers changes in a caste-specific manner when caste ratios are altered and demonstrate the importance of the major caste in colony defense. The population-level variation documented here for P. morrisi colonies supports the predictions of adaptive demography theory and illustrates that developmental mechanisms can play a significant role in shaping the evolution of phenotype at the colony level.

Adaptation, Biological↗
PubMed2006

An evaluation of the performance of the self-rating of the effects of alcohol questionnaire in 12- and 35-year-old subjects.

OBJECTIVE: A low level of response (LR) to alcohol was originally established through evidence of less alcohol-related change in several parameters at a given blood alcohol level. This is a genetically influenced phenotype associated with an increased risk for alcoholism. When measured by a retrospective questionnaire (the Self-Rating of the Effects of Alcohol [SRE] scale), a lower LR (here indicated by a report that more drinks were historically needed for various effects) correlates with a family history of alcoholism and numerous alcohol use-related variables. The current analyses address the questions of how higher SRE scores (as indicators of a low LR) relate to alcohol use and problems across different age groups and when considered in the context of demography (e.g., age, gender, and weight), as well as the number of items endorsed on the questionnaire. METHOD: SRE data (scores and numbers of items endorsed), demography, and alcohol-related variables (quantity, frequency, and problems) were evaluated in two populations. The first population included 334 12-year-old children from the Avon Longitudinal Study of Parents and Children, and the second included more than 400 35-year-old men from the San Diego Prospective Study. In each group, Pearson correlations were established among all variables, and items that were significantly linked to alcohol-related outcomes were entered into regression analyses as predictors of these outcomes. RESULTS: In both samples, SRE scores correlated with all alcohol-related outcomes, with the highest values for the maximum quantity of alcohol consumed. Relationships between the SRE score and alcohol-related variables remained robust in both populations when entered into regression analyses incorporating demography and the number of SRE items answered by subjects. CONCLUSIONS: The SRE score appears to perform relatively similarly across the two populations regarding relationships with alcohol quantity, frequency, and problems. The most consistent results were observed for the maximum quantity of alcohol consumed.

Adolescent↗
PubMed2006

Disentangling reasons for low Y chromosome variation in the greater white-toothed shrew (Crocidura russula).

Y chromosome variation is determined by several confounding factors including mutation rate, effective population size, demography, and selection. Disentangling these factors is essential to better understand the evolutionary properties of the Y chromosome. We analyzed genetic variation on the Y chromosome, X chromosome, and mtDNA of the greater white-toothed shrew, a species with low variance in male reproductive success and limited sex-biased dispersal, which enables us to control to some extent for life-history effects. We also compared ancestral (Moroccan) to derived (European) populations to investigate the role of demographic history in determining Y variation. Recent colonization of Europe by a small number of founders (combined with low mutation rates) is largely responsible for low diversity observed on the European Y and X chromosomes compared to mtDNA. After accounting for mutation rate, copy number, and demography, the Y chromosome still displays a deficit in variation relative to the X in both populations. This is possibly influenced by directional selection, but the slightly higher variance in male reproductive success is also likely to play a role, even though the difference is small compared to that in highly polygynous species. This study illustrates that demography and life-history effects should be scrutinized before inferring strong selective pressure as a reason for low diversity on the Y chromosome.

Animals↗
PubMed1996

The influence of hunting pressure on the social behavior of vertebrates.

The study of the influence of human hunting pressure on the social behavior of vertebrates requires a large background on both the hunting pressure and the social behavior of the species. Literature about this subject is relatively scarce. Most of the papers are restricted to shifts in demography, and are generally "species-specific". However, human hunting pressure can not only affect demography but also some factors of the social behavior of a species such as parental care, territoriality, reproductive behavior, group-size, fraying behavior, mating system, and intraspecific competition. The presence of hunters in the area can lead the animals to move out of their original home-rangers. This can breakup the social structure and can cause long-term effects on the demography of hunted as well as nearby populations, amplifying the impact of hunting. On the other hand, harvest can be compensated in territorial species by "surplus population" of non-territorial individuals. Moreover, alternatively, an increase in the reproductive activity, as a response to hunting pressure, can compensate its effects in some species. Understanding the implications of hunting pressure in the social behavior of vertebrates might be decisive to the establishment of wildlife management and conservation programs. Manipulative experiments might help us to model such complex interactions. The occurrence of qualitative and quantitative changes in vertebrate social behavior directly or indirectly related to human hunting pressure is reviewed and analyzed in this paper.

Animals↗
PubMed1994

Progress in demographic methodology.

"This paper examines developments in demographic methodology during the past decade or so. It focuses on methodological advances in the analysis of mortality of infants and young children, of adults, and on problems of mortality estimation in small populations. The other major areas reviewed here are related to the study of birth intervals, parity progression, proximate determinants of fertility, and the demography of the family. Concluding remarks relate the methodological issues to the information explosion in demography."

Adult↗
PubMedDate not supplied

Introduction: evolutionary theory and the search for a unified theory of fertility.

Demography and evolutionary biology share common origins but have divergent emphasis on the role of theory in understanding population phenomena. A unified theory of fertility would be beneficial in explaining variation in demographic characteristics across geographic and temporal gulfs and in integrating disparate perspectives. The six papers in this thematic collection represent a nascent but vital field: human evolutionary demography. These papers examine the ways in which evolutionary theory can inform, strengthen, and focus research on topics of long-standing interest to demographers by explicitly modeling the relationship of socioecological variables to life history traits. The papers demonstrate that an understanding of human life history evolution and the use of evolutionary theory as an organizing framework can lead to a productive reassessment of five areas, which are of long-standing concern to demographers, and which conventional demographic approaches have had limited success in understanding. These are conflicts of interest between parents and children and between men and women, the allocation of resources to competing and/or alternative forms of investment in reproduction and parenting, resource flow within the household, demographic transitions and particularly the fertility transition associated with economic development, and variation in life history characteristics such as fertility and mortality across populations. Future research integrating models of trait-environment correlation with models of individual information processing and decision-making will help identify areas of focus, revitalize current models, and play a leading role in the development of a unified theory of fertility applicable across societies and times.

Birth Rate↗
PubMed2002

Deconstructing death in paleodemography.

In 1992 in this Journal (Konigsberg and Frankenberg [1992] Am. J. Phys. Anthropol. 89:235-256), we wrote about the use of maximum likelihood methods for the "estimation of age structure in anthropological demography." More specifically, we presented a particular method (the "iterated age-length key") from the fisheries literature and suggested that the method could be used in human and primate demography and paleodemography as well. In our paper (section titled "Some Future Directions"), we spelled out two broad areas that we expected to see develop over the ensuing years. First, we felt that the use of explicit likelihood methods would open up interest in basic estimation issues, such as the calculation of standard errors for demographic estimates and the formulation of tests for whether samples differed in their demographic structure. Second, we felt that the time was ripe for hazards analyses that would incorporate the uncertainty in estimation that follows from using age "indicators" rather than known ages. While some of these developments have occurred during the last decade, few have been reported in the American Journal of Physical Anthropology. In this paper we resolve some issues from our 1992 paper, and attempt to redress this deficit in the literature by reviewing some recent developments in paleodemography over the past decade.

Adult↗
PubMed2005

Demographic analysis of antimicrobial resistance among Streptococcus pneumoniae: worldwide results from PROTEKT 1999-2000.

DESIGN: The influence of demographic factors upon antimicrobial resistance among 3362 isolates of Streptococcus pneumoniae from 25 countries was investigated, using univariate comparison and multivariate logistic regression. RESULTS: Eleven countries had significantly higher rates (Odds ratios [OR]: 2.50-64.79) of penicillin and/or erythromycin resistance than the UK. After taking country effects into account, rates of penicillin resistance (OR 1.98) and erythromycin resistance (OR 1.89) were significantly higher among infants than adults. Fewer (OR 0.69) erythromycin-resistant isolates were collected from male than female patients. There was no difference in the incidence of penicillin or erythromycin resistance among inpatients or outpatients. Penicillin resistance was more prevalent among ear swabs than blood cultures (OR 2.07). Erm(B), the predominant macrolide resistance mechanism across all age groups, was particularly prevalent among bronchoalveolar lavage (69.1%) and sinus (68.8%) isolates. Isolates possessing both erm(B) and mef(A) were generally collected from South Korea and were most common among infants and children (10.3%) and ear samples (17.3%). Telithromycin susceptibility was >99.5%, irrespective of demography. CONCLUSIONS: Although demography had a significant impact on antimicrobial resistance of pneumococci, telithromycin remained highly active across all demographic groups.

Adolescent↗
PubMed2006

Why evolutionary biologists should be demographers.

Evolution is driven by the propagation of genes, traits and individuals within and between populations. This propagation depends on the survival, fertility and dispersal of individuals at each age or stage during their life history, as well as on population growth and (st)age structure. Demography is therefore central to understanding evolution. Recent demographic research provides new perspectives on fitness, the spread of mutations within populations and the establishment of life histories in a phylogenetic context. New challenges resulting from individual heterogeneity, and instances where survival and reproduction are linked across generations are being recognized. Evolutionary demography is a field of exciting developments through both methodological and empirical advances. Here, we review these developments and outline two emergent research questions.

Animals↗
PubMed2000

Determinants of cariogenic snacking in adolescents in Belfast and Helsinki.

The aim of the study was to investigate the determinants of reported snack consumption in adolescents residing in Belfast, Northern Ireland and Helsinki, Finland. Ten % random samples of 14-15 yr old Belfast (n = 628) and Helsinki (n = 600) adolescents were obtained. A questionnaire assessed their demography, oral health knowledge, attitudes and the consumption of cariogenic snacks containing non-milk extrinsic sugars (NMES). Five hundred and eighty-nine (94%) questionnaires were returned in Belfast and 441 (74%) questionnaires in Helsinki. Belfast adolescents had significantly higher levels of oral health knowledge and higher consumption rates for snacks containing NMES. The Helsinki adolescents had more positive attitudes towards their oral health. Multivariant analysis showed that demography was the most direct determinant of cariogenic snacking. The acquisition of oral health knowledge played a minor role. There is a need to develop tailored and focused programmes to promote healthier snacking regimes in adolescents.

Adolescent↗
PubMed2001

Moderators of the influence of supervisor-subordinate similarity on subordinate outcomes.

Gender, racial, and ethnic similarity were examined for 2,883 subordinate-supervisor dyads in a military setting. All forms of demographic similarity were weakly associated with satisfaction with one's supervisor and continued membership in the Army. White subordinates under the supervision of non-Whites expressed the lowest level of satisfaction with supervision. Two moderators were examined: supervisory support of equal opportunity and the length of time worked with a supervisor. Results underscore the value of fine-grained analyses in the area of relational demography and the value of studying temporal dynamics associated with relational demography.

Adult↗
PubMed2001

Pemphigus in South Africa.

BACKGROUND: Pemphigus is an autoimmune disease characterized by intraepidermal blistering. We describe the demography, prevalence, clinical features, response to treatment, and human leukocyte antigen (HLA) characteristics of pemphigus in Kwa-Zulu Natal, South Africa. METHODS: All patients with pemphigus were prospectively recruited over 12 years from January 1987 to December 1999. The demography, clinical features, histology, and immunofluorescence (IF) were recorded. In a subset of patients, HLA tests were performed. RESULTS: One hundred and twelve patients had pemphigus. Pemphigus foliaceus (PF) was the commonest variant seen (62 patients) and 80% of these patients were black. The mean age was 43 years (12-93 years) and the male to female ratio was 1 : 1.4. Fifty patients had pemphigus vulgaris (PV), of whom 82% were Indian. The mean age of presentation of PV was 48 years (21-82 years). The male to female ratio was 1 : 1.7. There was no mucosal involvement in PF. PV patients had painful oral lesions. The mortality rate was 14% in the total sample (six in PV and two in PF). HLA-B8 was positive in 41% of patients with PF (P < 0.001). CONCLUSIONS: PF occurs more commonly in black people, while most cases in Indians present with the PV subtype. Pemphigus patients present with severe and extensive disease, and PV patients share features in common with patients from their land of origin (India), suggesting a genetic link.

Adult↗
PubMed2002

Demographic transition of the Swedish cystic fibrosis community--results of modern care.

Assessing the results of modern cystic fibrosis (CF)-care and estimating the future population and its demography is important to evaluate the treatment regimens and to calculate the future needs of health-care resources. This paper updates previous incidence calculations. It assesses the results of modern CF-care in terms of survival and changing demography in Sweden. The incidence of CF in Sweden was calculated as 1/5600 live-births. Of the CF-population alive in 1999, 45% were > or = 18 years old. The mean annual mortality rate since 1991 was 0.9% (+/-0.4) and the median age at death 26 years (range 0-72). Of those born > or = 1991, 95% were estimated to survive their 25th birthday. The incidence of CF in Sweden is low. Modern CF-care in Sweden shows good results. The CF-population is growing rapidly and the adult part of the population will soon be larger than the paediatric. Continuously adapted resources are required to assure the future treatment quality especially for the growing adult CF-population.

Adolescent↗
PubMed1999

Why hunter-gatherer populations do not show signs of pleistocene demographic expansions.

The mitochondrial DNA diversity of 62 human population samples was examined for potential signals of population expansions. Stepwise expansion times were estimated by taking into account heterogeneity of mutation rates among sites. Assuming an mtDNA divergence rate of 33% per million years, most populations show signals of Pleistocene expansions at around 70,000 years (70 KY) ago in Africa and Asia, 55 KY ago in America, and 40 KY ago in Europe and the Middle East, whereas the traces of the oldest expansions are found in East Africa (110 KY ago for the Turkana). The genetic diversity of two groups of populations (most Amerindian populations and present-day hunter-gatherers) cannot be explained by a simple stepwise expansion model. A multivariate analysis of the genetic distances among 61 populations reveals that populations that did not undergo demographic expansions show increased genetic distances from other populations, confirming that the demography of the populations strongly affects observed genetic affinities. The absence of traces of Pleistocene expansions in present-day hunter-gatherers seems best explained by the occurrence of recent bottlenecks in those populations, implying a difference between Pleistocene (approximately 1,800 KY to 10 KY ago) and Holocene (10 KY to present) hunter-gatherers demographies, a difference that occurred after, and probably in response to, the Neolithic expansions of the other populations.

Anthropology↗
PubMed1996

Demographic transition theory.

Demography is a science short on theory, rich in quantification. Nevertheless, demography has produced one of the best documented generalizations in the social sciences: the demographic transition. What is the demographic transition? Stripped to its essentials it is the theory that societies progress from a pre-modern regime of high fertility and high mortality to a post-modern regime of low fertility and low mortality. The cause of the transition has been sought in the reduction of the death rate by controlling epidemic and contagious diseases. Then, with modernization, children become more costly. Cultural changes weaken the importance of children. The increasing empowerment of women to make their own reproductive decisions leads to smaller families. Thus there is a change in values, emphasizing the quality of children rather than their quantity. In short, the fertility transition is becoming universal phenomenon, in which every country may be placed on a continuum of progress in the transition.

Demography↗