Elder women suffer from low or loss of fertility because of decreasing oocyte quality as maternal aging. As energy resource, mitochondria play pivotal roles in oocyte development, determining oocyte quality. With advanced maternal age, increased dysfunctions emerge in oocyte mitochondria, which decrease oocyte quality and its developmental potential. Mitochondria supplement as a possible strate...

Most models of speciation require gradual change and geographic or ecological isolation for new species to arise. Homoploid hybrid speciation occurred readily between Saccharomyces cerevisiae and Saccharomyces paradoxus. Hybrids had high self-fertility (about 82%), low fertility when backcrossed to either parental species (about 7.5%), and vigorous growth under different thermal environments th...

Newly available information on the excavation of the Portuguese Mesolithic shell middens, Cabeço da Arruda and Moita do Sebastião, has allowed reassessment of the paleodemography of the sites. Following the restudy of Arruda and an examination of Moita site structure, we now discuss the problem of arriving at a minimum number of individuals (MNI) for Moita and use the age distribution of the de...

This article examines the high prevalence of primary and secondary infertility in low-resource countries. Provision of assisted reproductive technology (ART) to overcome both female and male infertility is in line with the reproductive rights agenda developed at the International Conference on Population and Development (ICPD) in Cairo 15 years ago. In addition to the right to control fertility...

Nigeria and Ghana are the most densely populated countries in the West African sub-region with fertility levels above world average. Our study compared the two countries' fertility levels and their determinants as well as the differentials in the effect of these factors across the two countries. We carried out a retrospective analysis of data from the Nigeria and Ghana Demographic Health Survey...

Fertility in Japan dropped below replacement level in the middle of the 1970s and declined further since the middle of the 1980s, having reached the total fertility rate (TFR) of 1.42 in 1995. There is much evidence to show that such fertility decline occurred directly as the result of the rise in the proportion never married and the rise in the age at marriage and age at childbearing. In this ...

Background The health benefits of secondary education have been little studied. We undertook country-level longitudinal analyses of the impact of lengthening secondary education on health outcomes amongst 15-24 year olds. Methods Exposures: average length of secondary and primary education from 1980 to 2013.Data/Outcomes: Country level adolescent fertility rate (AFR), HIV prevalence and morta...

Since the transition to democracy in Spain in 1975, both total fertility and rates of church attendance of Catholics have dropped dramatically. In this study the 1985 and 1999 Spanish Fertility Surveys were used to investigate whether the significance of religion for fertility behaviour -- current family size and the spacing of births -- changed between the survey dates. In the 1985 survey, fam...

'Demographic transition theory' assumes that fertility decline is irreversible. This commonly held assumption is based on observations of recent and historical reductions in fertility that accompany modernization and declining mortality. The irreversibility assumption, however, is highly suspect from an evolutionary point of view, because demographic traits are at least partially influenced by ...