The 7 Sexes

Elof Axel Carlson

Description

The long search to understand the mystery of sex

Read an excerpt from the book

Few of us know much about the biology of sex determination, but what could be more interesting than to discover how we are shaped into males and females? In this book, Elof Carlson tells the incredible story of the difficult quest to understand how the body forms girls and boys. Carlson's history takes us from antiquity to the present day to detail how each component of human reproduction and sexuality was identified and studied, how this knowledge enlarged our understanding of sex determination, and how it was employed to interpret such little understood aspects of human biology as the origin of intersex births.

List of Tables
List of Figures
Preface
1. Introduction
2. Wild Guesses in an Era of Scientific Ignorance
3. The Ancient World
4. Monotheistic Religious Interpretations
5. The Descriptive Embryology of Male and Female Development
6. The Discovery of the Egg in Higher Eukaryotes
7. The Discovery of the Sperm in Higher Eukaryotes
8. The Discovery of Sex Hormones
9. Ploidy Levels and Sex Determination
10. The Discovery of Sex Chromosomes
11. The Balance Theory of Sex Determination
12. The Discovery of Sex in Microorganisms
13. The History and Interpretations of Hermaphrodites and Intersexes
14. Dosage Compensation and the Sex Chromosomes
15. The Discovery of Human Sex Chromosome Conditions
16. The Role of Sex Determining Genes
17. The Seven Sexes of Humans
18. The History of Homosexuality
19. The History of Behavioral Gender Assignment
20. The Evolution of Sex Determination
21. What Does It Mean to Have an Assigned Sex?
22. The Quest for a Unified Theory of Sex, Gender, and Sexuality
Appendix: Secondary Literature and the Relation of Biology to Sex and Gender
Glossary
Index

Sujets

• Human Sexuality
• Life Sciences
• Sociologie, société et politique
• Biology
• Psychology
• History of science
• Human sexual activity
• Genetic engineering
• 454 Life Sciences
• History
• LGBT
• Science

Informations

• Publié par: Indiana University Press
• Date de parution: 12 février 2013
• Nombre de lectures: 0
• EAN13: 9780253006547
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

The 7 Sexes
The 7 Sexes
BIOLOGY OF SEX DETERMINATION
ELOF AXEL CARLSON
This book is a publication of
Indiana University Press 601 North Morton Street Bloomington, Indiana 47404-3797 USA
iupress.indiana.edu
Telephone orders 800-842-6796 Fax orders 812-855-7931
2013 by Elof Axel Carlson
All rights reserved
No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and recording, or by any information storage and retrieval system, without permission in writing from the publisher. The Association of American University Presses Resolution on Permissions constitutes the only exception to this prohibition.
The paper used in this publication meets the minimum requirements of the American National Standard for Information Sciences-Permanence of Paper for Printed Library Materials, ANSI Z 39.48-1992.
Manufactured in the United States of America
Library of Congress Cataloging-in-Publication Data
Carlson, Elof Axel.
The 7 sexes : biology of sex determination / Elof Axel Carlson.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-253-00645-5 (cl : alk. paper) - ISBN 978-0-253-00654-7 (eb)
1. Sex determination, Genetic. I. Title. II. Title: Seven sexes.
QP 278.5. C 37 2013
612.6-dc23
2012030688
1 2 3 4 5 18 17 16 15 14 13
Dedicated to Alfred Charles Kinsey (1894-1956) who changed the discussion of human sexuality from ignorance and tradition to scientific findings .
CONTENTS
List of Tables
List of Figures
Preface
1 Introduction
2 Wild Guesses in an Era of Scientific Ignorance
3 The Ancient World
4 Monotheistic Religious Interpretations
5 The Descriptive Embryology of Male and Female Development
6 The Discovery of the Egg in Higher Eukaryotes
7 The Discovery of Sperm in Higher Eukaryotes
8 The Discovery of Sex Hormones
9 Ploidy Levels and Sex Determination
10 The Discovery of Sex Chromosomes
11 The Balance Theory of Sex Determination
12 The Discovery of Sex in Microorganisms
13 The History and Interpretations of Hermaphrodites and Intersexes
14 Dosage Compensation and the Sex Chromosomes
15 The Discovery of Human Sex Chromosome Conditions
16 The Seven Sexes of Humans
17 The Identification and Role of Sex-Determining Genes
18 The History of Homosexuality
19 The History of Behavioral Gender Assignment
20 The Evolution of Sex Determination
21 What Does It Mean to Have an Assigned Sex?
22 The Quest for a Unified Theory of Sex, Gender, and Sexuality
Afterword
Appendix: Secondary Literature and the Relation of Biology to Sex and Gender
Glossary
Notes
Index
LIST OF TABLES
Table 8.1
The Major Steroid Hormones in Humans
Table 9.1
Habrobracon (Wasp) Haplo-diploid Genetics of Sex Determination
Table 11.1
Bridges s Balance Theory of Fruit-Fly Sex Determination
Table 11.2
Sex-Determining Genes in the Fruit Fly
Table 15.1
X and Y Human Karyotypes Involving Normal and Defective Sex Chromosomes
Table 15.2
Sex Chromatin and Sex Chromosomes in Human Cells
Table 16.1
The Seven Sexual Components of Humans
Table 17.1
Some Major Genetic Disorders Associated with Sex Determination
Table 18.1
Status of Same-Sex Orientation through History
Table 22.1
Biological Diversity and Sexuality
Table 22.2
Classification of Conditions and Disorders of Sex Determination and Differentiation
LIST OF FIGURES
Figure 2.1
Twinning and Extra-Embryonic Membranes
Figure 3.1
Galen s Inside-Outside Model of Human Sex
Figure 4.1
The Transition from Medieval to Modern Representation of the Body
A. Hieronymous Brunschwig
B. Albrecht D rer
Figure 6.1
Ascaris versus Human Egg Formation
Figure 8.1
Structure of the Cholesterol Molecule
Figure 8.2
Reciprocal Pathways for Internal Genital Sex
Figure 10.1
The Discovery of Sex Chromosomes
Figure 10.2
Morgan s Discovery of X-linked Inheritance
A. White male red female
B. Red male white female
Figure 12.1
Bacterial Replication from Fission to Sexual Reproduction
A. Fission model
B. Bacterial mating
Figure 13.1
Human Chimera Formation
Figure 13.2
Gynandromorph Formation in Fruit Flies
Figure 14.1
Dosage Compensation versus Bicolorism
Figure 14.2
Sex-lethal (Sxl) Gene Regulation of Dosage Compensation in the Fruit Fly
Figure 14.3
Sex Chromatin Formation and Human Karyotypes
Figure 16.1
Alfred Jost Discovers a Second Male Hormone
Figure 17.1
The Human Y Chromosome
Figure 17.2
The Human X Chromosome
Figure 20.1
Isogamous and Anisogamous Mating in Single-Celled Organisms
Figure 20.2
Muller s Ratchet in Asexual and Sexual Populations
PREFACE
Every aspect of the history of sexuality is controversial. Eating, fashion, sports, occupation, or political outlook can be discussed freely in public, even by those who disagree. There is not the same intensity of unease that accompanies these aspects of our lives as it does sexuality. A major reason for this unease comes from religion. Religions, especially the monotheistic ones, have long held strong opinions on sex, mostly regulating sexual behavior and often describing transgressions as abominations, sins, or moral crimes leading to the fury of God or those representing God s views. A second reason for treating sexuality with fear, guilt, or embarrassment stems from our psychology. For Freudian psychiatrists, sexuality was the basis for all neurotic and psychotic conditions they interpreted or tried to help. Whether we treat psychiatric approaches with respect or disapproval as a healing science, we usually repress our sexual thoughts in public settings, and are awkwardly aware of the passing or fleeting moments of erotic awareness that shove themselves into our minds at inappropriate times. A third reason is cultural. Each community develops its own ideas about the differences in sexual behavior expected of males and females. These ideas sometimes reflect religious views, but often have their own expression in how we behave in our daily lives as men and women in society, which limits aspects of sexual behavior in public-from kissing, holding hands, exposing parts of our bodies without clothing, or hiding most of them, especially those parts usually associated with our sexual identification.
The same unease applies to the scientific study of sexuality. Each generation learns something more about the biology, psychology, or cultural history of sexuality. Society itself changes in the way it regards children born with sex disorders, just as it does for those born with birth defects not associated with sex. Since the 1980s, terms like mongoloid idiocy, juvenile amaurotic idiocy, and gargoylism have yielded to neutral terms like Down syndrome, Tay-Sachs syndrome, and Hurler syndrome. In a similar way, older terminology in the scientific literature is yielding to a new vocabulary for the twenty-first century. All forms of human hermaphroditism are now referred to as intersexuality. The generic term disorders of sex development (DSDs) or differences of sex development is gradually replacing older terms like male pseudohermaphrodite (46,XY DSD), female pseudohermaphrodite (46,XX DSD), true hermaphrodite (ovotesticular DSD), XX male sex reversal (46,XX testicular DSD), and XY female sex reversal (46,XY complete gonadal dysgenesis). 1 These new terms may be easier and more descriptive for the scientist to use, but they are more difficult for parents of such children when describing their child s condition to relatives and friends. Some may still have an alienating connotation and may be subject to further descriptive changes, or eventually they may be switched to neutralizing eponyms-as in Turner syndrome (for the human 45,X syndrome) or Klinefelter syndrome (for the 47,XXY syndrome).
In this history, I will use the older terms as they were in use at the time, but in the final chapters I will use the old or new terms (with their alternate terminology in brackets) so readers will not have to flip back and forth to Table 22.2 to know what is being discussed. Sexuality is a huge topic, and while all aspects of sexuality enter into the discussion of sex determination to some extent, the main emphasis in this book is the history of the biological processes that deal with the mechanisms and events that lead normally to male or female offspring. The term sex differentiation applies to the various components of our sexuality and how they are formed after the initial sex-determining event occurs. For humans, that initiating event is the union of an X- or Y-bearing sperm with an X-bearing egg. We have an XY sex-determining mechanism. It is not universal. I describe the other major forms of sex determination that occur in plants, animals, and even microbes. But once initiated, the differentiation process may also be elaborate-involving the formation of the gonads, the formation of the internal genitals, and the formation of the external genitals. What we see at birth and assign to a gender (legally restricted on birth certificates to male or female) is often limited to the external genitals. If we see a penis and scrotum, we assign a male status to the child. If we see the clitoris, labia, and a vaginal opening, we assign a female status. On occasion (and it is very rare) there will be an i