Geographic variation in personality is associated with fertility across the United States

Levels of fertility and the shape of the age-specific fertility schedule vary substantially across U.S. regions with some states having peak fertility relatively early and others relatively late. Structural institutions or economic factors partly explain these heterogeneous patterns, but regional differences in personality might also contribute to regional differences in fertility. Here, we evaluated whether variation in extraversion, agreeableness, conscientiousness, neuroticism, and openness to experience measured at the U.S. state-level was associated with the level, timing, and context of fertility across states above and beyond sociodemographics, voting behavior, and religiosity. Generally, states with higher levels of agreeableness and conscientiousness had more traditional fertility patterns, and states with higher levels of neuroticism and openness had more nontraditional fertility patterns, even after controlling for established correlates of fertility (r ~ |.50|). Personality is an overlooked correlate that can be leveraged to understand the existence and persistence of fertility differentials.

A demographic and evolutionary analysis of maternal effect senescence

Maternal effect senescence—a decline in offspring survival or fertility with maternal age—has been demonstrated in many taxa, including humans. Despite decades of phenotypic studies, questions remain about how maternal effect senescence impacts evolutionary fitness. To understand the influence of maternal effect senescence on population dynamics, fitness, and selection, we developed matrix population models in which individuals are jointly classified by age and maternal age. We fit these models to data from individual-based culture experiments on the aquatic invertebrate,Brachionus manjavacas(Rotifera). By comparing models with and without maternal effects, we found that maternal effect senescence significantly reduces fitness forB. manjavacasand that this decrease arises primarily through reduced fertility, particularly at maternal ages corresponding to peak reproductive output. We also used the models to estimate selection gradients, which measure the strength of selection, in both high growth rate (laboratory) and two simulated low growth rate environments. In all environments, selection gradients on survival and fertility decrease with increasing age. They also decrease with increasing maternal age for late maternal ages, implying that maternal effect senescence can evolve through the same process as in Hamilton’s theory of the evolution of age-related senescence. The models we developed are widely applicable to evaluate the fitness consequences of maternal effect senescence across species with diverse aging and fertility schedule phenotypes.

Maternal Effect Senescence and Fitness: A Demographic Analysis of a Novel Model Organism

Maternal effect senescence—a decline in offspring fitness with maternal age—has been demonstrated in a range of taxa, including humans. Despite decades of phenotypic studies, it remains unclear how maternal effect senescence impacts population structure or evolutionary fitness. To understand the impact of maternal effect senescence on population dynamics, fitness, and selection, we used data from individual-based culture experiments on the microscopic aquatic invertebrate, Brachionus manjavacas (Rotifera), to develop a series of matrix population models in which individuals are classified jointly by age and maternal age. By comparing the results derived from models with and without maternal effects, we found that the fitness difference due to maternal effect senescence arises primarily through decreased fertility, particularly at maternal ages corresponding to the peak reproductive output. In all models, selection gradients decrease with increasing age. They also decrease with maternal age for large maternal ages, implying that maternal effect senescence can evolve through the same process as in Hamilton’s theory of the evolution of demographic senescence. We find that maternal effect senescence significantly alters population structure and fitness for B. manjavacas, a species with high maternal investment and maximum reproduction in early-to mid-life. The models developed here were built with data from an emerging model organism, and are widely applicable to evaluate the fitness consequences of maternal effect senescence across species with diverse aging and fertility schedule phenotypes.

Hindu–Muslim Fertility Differentials in India: Indirect Estimation at the District Level from Census 2011

This article estimates the total fertility rate (TFR) for the overall population in major Indian states by employing Arriaga variation of the P/F ratio method and the relational Gompertz model. The article uses the 2011 Census data on average parity and the current fertility schedule. Estimation of TFRs at the state level by employing Arriaga variation of the P/F ratio method strongly corresponds with Sample Registration System (SRS) compared to those derived from the relational Gompertz model. Thus, Arriaga variation of the P/F ratio method was retained to estimate the Hindu–Muslim fertility differentials for 618 districts in India from all states except Jammu and Kashmir. Comparing the TFRs obtained from the analyses with indirect estimates of TFRs from the 2001 Census, the analysis reveals that the overall fertility transition in India has been steady during the last decade. Fertility transition has been underway for both Hindus and Muslims, at a varying pace, when compared to the state-level indirect estimates of the 2001 Census. Though the overall convergence of fertility between Hindus and Muslims has been underway, significant regional variations persist.

Tracing Mathematical Function of Age Specific Fertility Rate in Peninsular Malaysia

<p>The size, structure, and composition of a population are affected by the fertility rates at any point of time. Many researchers took the opportunity to exploit the fertility rates in obtaining better fertility patterns for their country. The curve for the age specific fertility rate is consistent, and this feature allows the curve to be matched with a mathematical model. This paper aimed to identify the best mathematical model that fits the recent age specific fertility rate in Peninsular Malaysia. This study fitted the fertility data of Peninsular Malaysia from 1996 to 2014 to the four mathematical models, which were Hadwiger, Gamma, Beta, and Gompertz models. From the comparisons of the four models, it was found that the best fitted mathematical model is Hadwiger model. In relation to the data of early 21st century, there was an inclination for the best fitted mathematical model from Hadwiger model to Beta model. Hence, the best mathematical model for each year can be used to convert a fertility schedule classified in a five-year age group into a fertility schedule for a single-year of age in Peninsular Malaysia. This model also can be helpful for population projections by using limited and defective data. </p>

East-west demographic divide in the EU: A regional overview

The goal was to examine demographic differences between former communist regions and other regions of the EU. Besides providing a regional overview of EU?s demographic differences, we question whether the subnational approach offers any new insights into the East-West divide. This cross-sectional study was conducted on 1,155 EU?s NUTS3 regions from 2014. These regions are grouped in two groups: regions that were part of a com-munist country, and other regions. Mortality, fertility and age structure indicators were tested between the two groups of regions. GDP/c was used to control for differences in economic development by segmenting the regions into tree brackets: low, medium, and high. The differences were then tested for each indicator. Regional variation within countries for each indicator was also assessed. The gaps exist at regional level and are the widest with mortality and fertility schedule, regardless of GDP/c. Former communist regions on average tend to be slightly younger. Analysis of regional variation showed that subnational approach was warranted when studying East-West demographic disparities, especially when it comes to fertility schedule. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 47006: Istrazivanje demografskih fenomena u funkciji javnih politika u Srbiji]

Transition in risks of higher order births in Nepal: a life table analysis

This paper examines declining fertility in a low development setting. Specifically, this paper analyzes transitions in age at first birth and of the length of birth intervals, the variations of the length of birth intervals by selected socioeconomic and demographic factors, and the determinants of the risk of higher order birth in Nepal by using the DHS data. There is very little change in the age at start of fertility schedule but the proportion of women progressing to the next higher order birth from the second, third and fourth births has declined over time. Increases in the median length of higher order birth intervals and decline in the ultimate proportions of women attaining higher order births drive declines in the pace of childbearing and overall fertility level. Controlling for other factors, higher order births are more likely among women who had given a previous birth before the survey period or women who had a female birth compared to women who did not have such births. Significantly, lower hazard ratio of the second birth is observed among women who are more educated, working in non-agriculture sector, from well-to-do households, with higher age at first birth, and whose first child survived during infancy.

Ultimate Population Size under Changed Age Specific Fertility Schedule

This paper attempts to obtain ultimate population size under changed age specific fertility schedule. The reduction in fertility under exponential and linear decline has been discussed in order to obtain ultimate population size. A concept has been suggested to obtain ultimate population size by combining both exponential and linear decline pattern in age schedule due to faster reduction in fertility at the beginning and thereafter slower declining rate in fertility age schedule.Journal of Institute of Science and Technology, 2015, 20(1): 138-140

Population Projection under Changing Fertility Conditions

This paper attempts to derive model for population projection under gradual change in fertility schedule on stability conditions using birth trajectory at time t for 0 < t ? a . The projected population can be obtained when the data of the rate of natural increase, net reproduction rate, age variance of the net maternity function, birth rate of the initial stable population along with its age distribution are available of the population.Journal of Institute of Science and Technology, 2014, 19(2): 86-88