Social Networks and the Heritability of Migratory Behavior.

A small but growing body of literature examines the relationship between genetics and human migration. These studies suggest that some DRD4 alleles, particularly 7R+, are related to migration. This is surprising from a sociological perspective, which views migration largely as a product of social and economic forces.

Heterogeneity identified at birth and blood pressure in adulthood.

Objective: In the developmental programming literature, the association of birth weight and blood pressure later in life is modest at best. This article reexamines this issue using Covariate Density Defined mixture of regressions (CDDmr) to determine if a latent variable, based on birth weight, and known to influence infant mortality, provides a stronger indicator of developmental programming.

Methods: CDDmr identifies two latent components in the birth weight distribution, generally interpreted in the infant mortality literature as "compromised" and "normal" fetal development.

The effect of intra-uterine growth restriction on blood lipids and response to exercise training.

Objectives: To determine if a small body size at birth is associated with an unfavorable metabolic profile and a reduced response to exercise training in young adults.

Methods: Thirty-six college students, all singletons born to term, participated. Subjects were defined as either high ponderal index (HIGHPI) or low ponderal index (LOWPI).

Maternal education, birth weight, and infant mortality in the United States.

This research determines whether the observed decline in infant mortality with socioeconomic level, operationalized as maternal education (dichotomized as college or more, versus high school or less), is due to its "indirect" effect (operating through birth weight) and/or to its "direct" effect (independent of birth weight). The data used are the 2001 U.S.

Low ponderal index is associated with decreased muscle strength and fatigue resistance in college-aged women.

Poor fetal growth is associated with decrements in muscle strength likely due to changes during myogenesis. We investigated the association of poor fetal growth with muscle strength, fatigue resistance, and the response to training in the isolated quadriceps femoris. Females (20.

Racial disparities in infant mortality: what has birth weight got to do with it and how large is it?

Background: It has been hypothesized that birth weight is not on the causal pathway to infant mortality, at least among "normal" births (i.e. those located in the central part of the birth weight distribution), and that US racial disparities (African American versus European American) may be underestimated.

What do we know about the agricultural demographic transition?

The Agricultural Revolution accompanied, either as a cause or as an effect, important changes in human demographic systems. The consensus model is that fertility and mortality increased and health declined with the adoption of agriculture, compared to those for hunter-gatherers. Analysis of the agricultural transition relies primarily on archaeological and paleodemographic data and is thus subject to the errors associated with such data.

Modeling the pediatric paradox: birth weight by gestational age.

The "pediatric paradox" of African versus European American infant mortality is often observed with respect to birth weight, but rarely to gestational age, even though the two measures are biologically related. This paper models the pediatric paradox by birth weight and gestational age simultaneously, using Covariate Density Defined mixture of logistic regressions (CDDmlr) fitted to 1985-1988 New York State births. The model controls for unobserved heterogeneity and isolates the pediatric paradox in the "compromised" subpopulation.

Maternal age and infant mortality: a test of the Wilcox-Russell hypothesis.

It has been argued (e.g., the Wilcox-Russell hypothesis) that (low) birth weight is a correlate of adverse birth outcomes but is not on the "causal" pathway to infant mortality.

Multiple mortality optima due to heterogeneity in the birth cohort: a continuous model of birth weight by gestational age-specific infant mortality.

Birth weight and gestational age are both important predictors of infant survival. Covariate Density Defined mixture of logistic regressions (CDDmlr), a method that accounts for unobserved heterogeneity, has been applied to birth outcomes using birth weight alone. This paper investigates a CDDmlr model of birth outcomes that includes birth weight and gestational age.

Are modern environments really bad for us?: revisiting the demographic and epidemiologic transitions.

It is a common assumption that agriculture and modernization have been detrimental for human health. The theoretical argument is that humans are adapted to hunter-gatherer lifestyles, and that the agricultural and "modern" environments are novel and hence likely to be detrimental. In particular, changes in nutrition, and population size and distribution with the adoption of agriculture, are considered to increase the risk of infectious disease mortality.

Pediatric paradox: heterogeneity in the birth cohort.

Comparisons of birth-weight-specific infant mortality indicate that low-birth-weight African American infants have lower mortality than low-birth-weight European American infants despite higher infant mortality overall-the "pediatric paradox." One explanation is heterogeneity in birth weight. Analyses of African American and European American births suggest that birth cohorts consist of two heterogeneous subpopulations.

Has the transition to agriculture reshaped the demographic structure of prehistoric populations? New evidence from the Levant.

This paper presents the demographic changes that followed the transition from a hunting-gathering way of life (Natufian) to an agricultural, food-producing economy (Neolithic) in the southern Levant. The study is based on 217 Natufian (10,500-8,300 BC) skeletons and 262 Neolithic (8,300-5,500 BC) skeletons. Age and sex identification were carried out, and life tables were constructed.

The evolution of human phenotypic plasticity: age and nutritional status at maturity.

Several evolutionary optimal models of human plasticity in age and nutritional status at reproductive maturation are proposed and their dynamics examined. These models differ from previously published models because fertility is not assumed to be a function of body size or nutritional status. Further, the models are based on explicitly human demographic patterns, that is, model human life-tables, model human fertility tables, and, a nutrient flow-based model of maternal nutritional status.

Modeling birthweight and gestational age distributions: additive vs. multiplicative processes.

Researchers have traditionally employed Gaussian distributions to model quantitative biological traits. Recently, mixtures of Gaussian distributions have begun to be used as well. However, there are many alternatives to the Gaussian distribution.

Birth-weight-specific infant and neonatal mortality: effects of heterogeneity in the birth cohort.

Birth-weight-specific infant mortality is examined using a novel statistical procedure, parametric mixtures of logistic regressions. The results indicate that birth cohorts are composed of two or more subpopulations that are heterogeneous with respect to infant mortality. One subpopulation appears to account for the "normal" process of fetal development, while the other, which accounts for the majority of births at both low and high birth weights, may represent fetuses that were "disturbed" during development.

Variability of gestational age distributions by sex and ethnicity: An analysis using mixture models.

As an antecedent of birthweight and in its own right, gestational age is an important proximate determinant of infant mortality. Recent analyses using mixture models of birthweight distributions suggest that substantial heterogeneity occurs within a birth cohort even when controlling for sex and ethnicity. This article extends the mixture model analysis to gestational age.

Model life table for captive chimpanzees.

Mortality statistics from three captive populations of chimpanzees (Pan troglodytes) were combined to generate standard model life tables for each sex in this species. The model is compared to an estimate of survivorship of a group of wild animals, and is applied to an incomplete data set to illustrate how the model may be used to extend estimates of mortality statistics to missing older ages. © 1995 Wiley-Liss, Inc.

Anthropometric indicators of nutritional status and level of mortality.

The strength of the relationship between several anthropometric indicators of nutritional status, or more generally, standard of living, with overall mortality at the population level is compared. The anthropometic indicators examined include height, weight, weight-for-height, and weight-for-height at various ages. The results demonstrate that height is most closely associated with the level of mortality.

Model life tables for the smaller new world monkeys.

Mortality statistics from five populations of small New World monkeys (includinsg Callithrix jaccus, Leontopithecus rosalia, Saguinus fuscicollis, and Saguinus oedipus) were combined to generate a standard model life table reflecting the mortality patterns of these primates. The model is applied to three individual populations to illustrate a strategy for smoothing and interpolating mortality statistics of varying completeness and quality. © 1993 Wiley-Liss, Inc.

Model life tables for the larger old world monkeys: A revision.

We report a change in the method of averaging parameters of the Siler mortality model fitted to a series of Old World monkey survivorship schedules. Substitution of geometric for arithmetic means of multipliers of exponential terms avoids incorrect weighting of parameters. These changes have minor effects on the composite standard mortality schedule for these animals originally described in 1988.