Gay, Straight, and the Reason Why: The Science of Sexual Orientation

by Simon LeVay

Overview

What causes a child to grow up gay or straight? Neuroscientist Simon LeVay summarizes a wealth of scientific evidence that points to one inescapable conclusion: Sexual orientation results primarily from an interaction between genes, sex hormones, and the cells of the developing body and brain. LeVay takes the reader on a whirlwind tour of laboratories that specialize in genetics, endocrinology, neuroscience, cognitive psychology, evolutionary psychology, and family demographics. He describes, for instance, how researchers have manipulated the sex hormone levels of animals during development, causing them to mate preferentially with animals of their own gender. In this second edition, LeVay adds a chapter on bisexuality, reviews some uncommon forms of sexuality, and considers whether there could be a biological basis for subtypes of gay people such as "butch" and "femme" lesbians.

Product Details

ISBN-13:	9780190297398
Publisher:	Oxford University Press
Publication date:	08/01/2016
Sold by:	Barnes & Noble
Format:	eBook
Pages:	400
File size:	2 MB

About the Author

Simon LeVay, PhD, has served on the faculties of Harvard Medical School and the Salk Institute for Biological Studies. He has written eleven books, including the New York Times best-seller When Science Goes Wrong (2008) and the textbook Discovering Human Sexuality (2015).

Table of Contents

Introduction Chapter 1: What Is Sexual Orientation? Criteria for sexual orientation Sexual orientation in men and women Stability of sexual orientation Prevalence of different orientations Are there categories? Sexual orientation across cultures Chapter 2: Why We Need Biology Psychoanalytic theories Learning theories-influence of early sexual experiences Childhood abuse Learning theories-gender learning Is it a choice? The biological alternative Chapter 3: The Outline of a Theory Male and female brains Male and female behaviors Development of sex differences in animals Sexual partner preference in animals Origins of variation within each sex Relevance to human sexual orientation Sexual orientation in nature Chapter 4: Childhood Development of gendered childhood traits Childhood traits associated with adult sexual orientation: retrospective studies Prospective studies Contrasting models Chapter 5: Characteristics of gay and straight adults Gendered traits in adulthood Origin of gendered traits Sexual orientation and cognitive traits: visuospatial abilities Verbal fluency Memory tasks Handedness Olfaction Intelligence Personality traits: Masculinity-femininity Occupational preferences Other personality traits Sexuality Overview Chapter 6: The role of sex hormones Hormone levels in gay and straight adults Why focus on prenatal sex hormones? Hormone levels during development Congenital adrenal hyperplasia Finger length studies The inner ear Central auditory system Action of sex hormones on the developing brain Possible causes of variability in prenatal androgen levels Chapter 7: The role of genes Sibling studies Is the family clustering caused by genes? Twin studies Molecular genetics-candidate-gene studies Genome scans Genes and sexuality in fruit flies Genes, homosexuality, and evolution Kin selection The "fertile female" hypothesis Beneficial effects on same-sex relatives Chapter 8: The brain A brief tour of the brain The hypothalamus and sexual orientation Other brain regions Brain activity Chemosignals Stress response Functional lateralization Sheep Inhibition and sexual orientation Overview Chapter 9: The body Body size and shape Trunk and limb length Penis size Sturcture of the face Hair whorl direction Gaydar Overview Chapter 10: The older-brother effect How well established is the older-brother effect? How strong is the older-brother effect? The older-brother effect and handedness What causes the older-brother effect? Chapter 11: Beyond gay and straight Bisexuality in men Bisexuality in women Asexuality Age preference and pedophilia Butch-femme and top-bottom Transgender/transexuality Chapter 12: Conclusions Sexual orientation is linked to other gendered traits A common origin for gender-shifted traits? The role of genes Does the older-brother effect work through prenatal hormones? Is there a random biological influence? How does sexual orientation become categorical? Unconscious processes in sexual attraction and arousal Changes in the prevalence and nature of homosexuality What is sexual orientation? Sexual orientation and gender: the social fallout Glossary Bibliography

Editorial Reviews

The nature vs. nurture wars over the development of homosexuality have been pretty definitively decided in favor of nature. In this survey of what makes people gay, lesbian, bi, or straight, neuroscientist LeVay (When Science Goes Wrong) brings readers up-to-date on the current state of knowledge. Other recent books have covered much of the same territory, but LeVay's is the most comprehensive. He begins by tackling the seemingly simple question "What is sexual orientation?" As the book progresses, he discusses how gayness is not monolithic; rather, there seems to be different kinds of homosexuality. Some people claim to be able to identify gays using "gaydar," but LeVay says differences between straights and gays go beyond body language to include visuospatial abilities (e.g., lesbians, like straight men, have better spatial abilities than straight women) and verbal fluency. He reviews current thinking on the role of genes and how testosterone levels may influence the fetus's development. LeVay comes close at times to dry recitation of research results, but although the book's chief appeal probably will be to professionals dealing with these issues, other interested readers will find it an informative and generally approachable read. 20 b&w line drawings. (Oct.)

Publishers Weekly

"Although the book's chief appeal probably will be to professionals dealing with these issues, other interested readers will find it an informative and generally approachable read." --Publishers Weekly

"Simon LeVay, a former Harvard neuroscientist, has written, Gay, Straight, and the Reason Why: The Science of Sexual Orientation, a comprehensive, engaging and occasionally quite funny look at the current state of the research on the topic." --Schuyler Velasco, Salon

"This book will serve both as a resource for researchers looking for what is yet unknown and what questions need further research and as a fascinating read for the educated layperson, who will be intrigued by some of the factors that may relate to homosexuality... Recommended." -- Choice

"LeVay also does a nice job illustrating that the argument for sexual orientation as determined is not a singular cause-and-effect argument...Yet, it is important for scholars and clinicians alike across various paradigms to be aware of the research reviewed in Gay, Straight, and the Reason Why." --PsycCritiques

"Simon LeVay's book, Gay, Straight, and the Reason Why, offers an excellent review of scientific research on the causes and correlates of sexual orientation. It provides a clear and comprehensive summary of recent studies of sexual orientation- a review that should be useful to lay people and journalists as well as to professionals in the field. LeVay has a knack for describing complicated scientific topics- brain anatomy, behavior genetics, endocrinology, cognitive psychology- in straight-forward and easy-to-understand ways. He provides the reader with a good sense of where research on sexual orientation stands today, and where further research is needed." -- Richard Lippa, Sex Roles

"The theory that sexual orientation has a biological basis receives support in neuroscientist Simon LeVay's book. Relating evidence from genetics, neuroscience and developmental biology, he suggests that prenatal interactions between hormones and the developing brain influence adult sexuality." -- Nature

From the Publisher