Partnership Status and the Human Sex Ratio at Birth

Partnership Status and the Human Sex Ratio at Birth PDF Author: Karen Norberg
Publisher:
ISBN:
Category : Families
Languages : en
Pages : 22

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Book Description
If two-parent care has different consequences for the reproductive success of sons and daughters, then natural selection may favor adjustment of the sex ratio at birth according to circumstances that forecast later family structure. In humans, this partnership status hypothesis predicts fewer sons among extra-pair conceptions, but the rival "attractiveness" hypothesis predicts more sons among extra-pair conceptions, and the "fixed phenotype" hypothesis predicts a constant probability of having a son, regardless of partnership status. In a sample of 86,436 human births pooled from five US population-based surveys, I find 51.5% male births reported by respondents who were living with a spouse or partner before the child's conception or birth, and 49.9% male births reported by respondents who were not (X2=16.77, d.f. = 1, p

Partnership Status and the Human Sex Ratio at Birth

Partnership Status and the Human Sex Ratio at Birth PDF Author: Karen Norberg
Publisher:
ISBN:
Category : Families
Languages : en
Pages : 22

Get Book Here

Book Description
If two-parent care has different consequences for the reproductive success of sons and daughters, then natural selection may favor adjustment of the sex ratio at birth according to circumstances that forecast later family structure. In humans, this partnership status hypothesis predicts fewer sons among extra-pair conceptions, but the rival "attractiveness" hypothesis predicts more sons among extra-pair conceptions, and the "fixed phenotype" hypothesis predicts a constant probability of having a son, regardless of partnership status. In a sample of 86,436 human births pooled from five US population-based surveys, I find 51.5% male births reported by respondents who were living with a spouse or partner before the child's conception or birth, and 49.9% male births reported by respondents who were not (X2=16.77, d.f. = 1, p

The Descent of Human Sex Ratio at Birth

The Descent of Human Sex Ratio at Birth PDF Author: Éric Brian
Publisher: Springer Science & Business Media
ISBN: 140206036X
Category : Social Science
Languages : en
Pages : 263

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Book Description
This is an attempt to renew our links with the oldest traditions of scholarly thinking, but is also a well-tempered reflection on today’s work in objectivization. After a deconstruction of the past and present conditions of scientific understanding of human sex-ratio at birth, the authors propose a reconstruction of the dynamics of the phenomenon based on stochastics. Appendices provide information on the first expression of sex ratio trends, as well as a comparison of Darwin’s treatments of the subject.

Partinership Status and Teh Human Sex Ratio at Birth

Partinership Status and Teh Human Sex Ratio at Birth PDF Author: Karen Norberg
Publisher:
ISBN:
Category :
Languages : en
Pages : 22

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Book Description


Exploring the Biological Contributions to Human Health

Exploring the Biological Contributions to Human Health PDF Author: Institute of Medicine
Publisher: National Academies Press
ISBN: 0309132975
Category : Medical
Languages : en
Pages : 287

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Book Description
It's obvious why only men develop prostate cancer and why only women get ovarian cancer. But it is not obvious why women are more likely to recover language ability after a stroke than men or why women are more apt to develop autoimmune diseases such as lupus. Sex differences in health throughout the lifespan have been documented. Exploring the Biological Contributions to Human Health begins to snap the pieces of the puzzle into place so that this knowledge can be used to improve health for both sexes. From behavior and cognition to metabolism and response to chemicals and infectious organisms, this book explores the health impact of sex (being male or female, according to reproductive organs and chromosomes) and gender (one's sense of self as male or female in society). Exploring the Biological Contributions to Human Health discusses basic biochemical differences in the cells of males and females and health variability between the sexes from conception throughout life. The book identifies key research needs and opportunities and addresses barriers to research. Exploring the Biological Contributions to Human Health will be important to health policy makers, basic, applied, and clinical researchers, educators, providers, and journalists-while being very accessible to interested lay readers.

The Physiology of Human Pregnancy

The Physiology of Human Pregnancy PDF Author: Frank E. Hytten
Publisher: Wiley-Blackwell
ISBN:
Category : Health & Fitness
Languages : en
Pages : 622

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Book Description


Bare Branches

Bare Branches PDF Author: Valerie M. Hudson
Publisher: National Geographic Books
ISBN: 0262582643
Category : Political Science
Languages : en
Pages : 0

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Book Description
What happens to a society that has too many men? In this provocative book, Valerie Hudson and Andrea den Boer argue that, historically, high male-to-female ratios often trigger domestic and international violence. Most violent crime is committed by young unmarried males who lack stable social bonds. Although there is not always a direct cause-and-effect relationship, these surplus men often play a crucial role in making violence prevalent within society. Governments sometimes respond to this problem by enlisting young surplus males in military campaigns and high-risk public works projects. Countries with high male-to-female ratios also tend to develop authoritarian political systems. Hudson and den Boer suggest that the sex ratios of many Asian countries, particularly China and India—which represent almost 40 percent of the world's population—are being skewed in favor of males on a scale that may be unprecedented in human history. Through offspring sex selection (often in the form of sex-selective abortion and female infanticide), these countries are acquiring a disproportionate number of low-status young adult males, called "bare branches" by the Chinese. Hudson and den Boer argue that this surplus male population in Asia's largest countries threatens domestic stability and international security. The prospects for peace and democracy are dimmed by the growth of bare branches in China and India, and, they maintain, the sex ratios of these countries will have global implications in the twenty-first century.

Sex Ratios

Sex Ratios PDF Author: Ian Hardy
Publisher:
ISBN: 9780511069932
Category : Sex determination, Genetic
Languages : en
Pages : 424

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Book Description
Sex ratios, the proportions of males and females in any given species, are important in evolutionary and behavioural ecology. This volume explores the context to and methods for many aspects of research on sex ratios, and will be an indispensable reference for all those working in this area.

Sex Selection of Children

Sex Selection of Children PDF Author: Neil G. Bennett
Publisher: Elsevier
ISBN: 0323158250
Category : Science
Languages : en
Pages : 277

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Book Description
Sex Selection of Children explores the strategies used to control the sex of children, the conditions under which a couple would employ a given technique, and the technology to achieve their desired family composition. It also considers the social consequences of sex-selection techniques, the legal factors that might impinge on the use of such a technology, and the ethical considerations associated with its use. Organized into 10 chapters, this book begins with an overview of some of the more humorous past approaches to sex selection. It then discusses the effects of sex selection on fertility, sex selection by means of amniocentesis and selective abortion, and the theorized link between the timing of fertilization and the sex ratio of offspring. A chapter considers a decision-making model that describes the use of sex-selection techniques by couples who wish to have a specific number of children over their entire childbearing period, while another chapter analyzes the economics of sex preference and selection. The remaining chapters address the parental preferences about the sexes of their offspring in different societies, the legal aspects of prenatal sex selection, a moral policy for sex choice, and the ethics and public policy on sex choice. This book is a valuable resource for specialists involved in fields ranging from sociology and economics to biology, public health, law, and ethics.

The Laboratory Primate

The Laboratory Primate PDF Author:
Publisher: Elsevier
ISBN: 008045416X
Category : Medical
Languages : en
Pages : 639

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Book Description
A volume in the Handbook of Experimental Animals series, The Laboratory Primate details the past and present use of primates in biomedical research, and the husbandry, nutritional requirements, behaviour, and breeding of each of the commonly used species. Practical information on regulatory requirements, not available in other texts, is covered. Sections on experimental models cover the major areas of biomedical research, including AIDS, cancer, neurobiology and gene therapy. Assisted reproductive technology, tissue typing, and minimum group sizes for infectious disease/vaccine studies are also included. - Two-color, user-friendly format, with copious illustrations and color plates - Includes detailed, well-illustrated sections on gross & microscopic anatomy, common diseases, and special procedures, including surgical techniques

Sex Allocation

Sex Allocation PDF Author: Stuart West
Publisher: Princeton University Press
ISBN: 1400832012
Category : Science
Languages : en
Pages : 480

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Book Description
Recent decades have witnessed an explosion of theoretical and empirical studies of sex allocation, transforming how we understand the allocation of resources to male and female reproduction in vertebrates, invertebrates, protozoa, and plants. In this landmark book, Stuart West synthesizes the vast literature on sex allocation, providing the conceptual framework the field has been lacking and demonstrating how sex-allocation studies can shed light on broader questions in evolutionary and behavioral biology. West clarifies fundamental misconceptions in the application of theory to empirical data. He examines the field's successes and failures, and describes the research areas where much important work is yet to be done. West reveals how a shared underlying theoretical framework unites findings of sex-ratio variation across a huge range of life forms, from malarial parasites and hermaphroditic worms to sex-changing fish and mammals. He shows how research on sex allocation has been central to many critical questions and controversies in evolutionary and behavioral biology, and he argues that sex-allocation research serves as a key testing ground for different theoretical approaches and can help resolve debates about social evolution, parent-offspring conflict, genomic conflict, and levels of selection. Certain to become the defining book on the subject for the next generation of researchers, Sex Allocation explains why the study of sex allocation provides an ideal model system for advancing our understanding of the constraints on adaptation among all living things in the natural world.