The psychology of
gender and sexuality
An introduction
Open University Press
Buckingham · Philadelphia
Open University PressCeltic Court 22 BallmoorBuckinghamMK18 1XW email: [email protected] wide web: www.openup.co.uk and325 Chestnut StreetPhiladelphia, PA 19106, USA All rights reserved. Except for the quotation of short passages for the purposeof criticism and review, no part of this publication may be reproduced, storedin a retrieval system, or transmitted, in any form or by any means, electronic,mechanical, photocopying, recording or otherwise, without the prior writtenpermission of the publisher or a licence from the Copyright Licensing AgencyLimited. Details of such licences (for reprographic reproduction) may beobtained from the Copyright Licensing Agency Ltd of 90 Tottenham CourtRoad, London, W1P 0LP.
A catalogue record of this book is available from the British Library Library of Congress Cataloging-in-Publication Data
Stainton Rogers, Wendy.
The psychology of gender and sexuality : an introduction / Wendy Stainton Rogers and Rex Stainton Rogers.
Includes bibliographical references and index.
ISBN 0-335-20225-X (hardcover) — ISBN 0-335-20224-1 (pbk.)1. Sex (Psychology) 2. Sex. 3. Sex differences (Psychology) I.
Stainton Rogers, Rex. II. Title.
BF692.S72 2000155.3—dc21 Typeset by Graphicraft Limited, Hong KongPrinted in Great Britain by Biddles Limited, Guildford and King’s Lynn Contents
Mainstream psychological approaches to
gender and sexuality

Biological paradigms
Social and cultural paradigms
The contribution of anthropology: the role of culture The contribution of sociology: the role of social forces The contribution of psychology: the role of socialization Interactive paradigms
Eysenck’s theories of gender and sexuality Freud’s psychoanalytic theories of personality and The challenges to mainstream approaches
Introduction to Part II: Challenges
Challenges to Modernism: the climate of perturbation Liberatory challenges
Liberalism as a ‘best-of-all-possible-worlds’ philosophy Research into the effects of pornography and erotica Feminist challenges
We’re all postfeminists now – aren’t we? Postmodern challenges
Applications of a critical approach
Where’s the action?
Aliens and others
Science fiction as a deconstructive device Alternative analytics and the challenge for psychology Sex crimes
New men, new women, new relationships?
In the usual way I would like to thank Rebekah Stainton Rogers, LukeWray and Susannah Chappell for help with the bibliography. Also thepeople who reviewed the original proposal, and Robin Long, HarriettMarshall and Paul Stenner who reviewed the final manuscript. Their com-ments and suggestions were so useful that we acted on most of them.
But I would also like to add my thanks to all those who made com- pleting the book possible. I should mention here both the long-sufferingJustin Vaughan at Open University Press, and my friends and colleaguesat the Open University, especially Pam Foley, Stan Tucker and JeremyRoche, who took on large sections of my work to give me the space andtime to devote to the book.
Finally, though, I would like to thank all the many people who have supported me over the past year – my daughters Amanda, Karina andRebekah; my sisters Sally and Pam; my wider family, my friends, my neigh-bours, my doctor, my chiropractor, my gardener, my heating engineer,my cleaner and my builders. I’m sorry I can’t name you all, for fear ofmissing anybody out – you know who you are. But I could not have gotthrough the months since Rex died without all of your love, tenderness,thoughtfulness, kindness and help. I will remain always deeply grateful.
Rex and I worked on this book throughout most of 1998. It would be trueto say that it dominated our lives that year. For most of the time Rexwas on sabbatical, and he divided his time between what came to be called‘Rex’s Erection’ (a deck and greenhouse he built – although neither ofthese words conveys the reality of the amazing structure he created) andwriting first drafts of many of the chapters. I put in most evenings andweekends, as well as vacation times – we worked through all three. I cannot count the hours we spent beavering away, him upstairs, me down,meeting regularly in the kitchen to confer, to plot and plan, to talk throughwhat we would each do next, and, of course, to argue – it was out ofour arguments that our best writing came.
We gave up on taking a holiday that summer. But I do remember the autumn day when we decided that the sun was shining so gloriously thatwe had to go out and enjoy it. We walked by Wittenham Clumps toDorchester, saying to one another: ‘Blow the book’ (or words to that effect)‘there are too few days like this in life, and they should not be spent atthe desk.’ That day was a precious one.
It was not always easy writing as a couple. I remember wryly com- menting several times to my friends that whereas most co-authors have tocatch you on the phone to nag you – ‘How’s Chapter 3 getting on then?’– with Rex this usually happened when he dug me in the ribs in bed inthe morning, just as I was waking up. My replies were far from polite,although usually after breakfast together and several cups of coffee thenegotiation would be calmer and more constructive. It was hard work,but I have many happy memories of those times – writing a book withsomeone you love can be an incredibly rewarding experience.
The first draft of the book was completed in December 1998, and a couple of weeks into the new year Rex and I began to work on the amend-ments suggested by our editor at Open University Press, Justin Vaughan.
But Rex was taken seriously ill in January, and, indeed, his last con-tributions to the manuscript were made while he was recovering in hospital. Two weeks later, on 8 February 1999, Rex died. This book will be his last published work, completing an incredibly diverse and influential publishing career.
Not surprisingly, it has been very painful for me to finish the book, and it has taken some time before I could face this task – thank you, Justin,for being so understanding. But now I have, and I hope I have not donetoo much violence to Rex’s text in the changes and deletions I have made.
I would have given anything to have had him here to argue and battleits completion. We had spent more than 26 years writing together. Thebattles were hard, the arguments often heated – but they were such enjoyable battles, such marvellous arguments! I will miss, dreadfully, hissheer intellectual vivacity, his inventiveness and his wicked, wicked waywith words – and I am not the only person who feels like that.
Rex was often not an easy man to work with (or indeed to live with).
At times he drove me crazy with frustration, and I know he was a thorn inthe flesh of many others. He would never have wanted to be sanctifiedor put on a pedestal, and I am not going to pretend he was a saint. Buthe was the most amazing, incredible man – an inspirational man; a manof immense warmth, generosity, kindness and charisma. Like so manyothers, I miss him dreadfully. But he lives on, in the lives he influenced,in the gifts of hope and courage and inspiration he gave to so many –the students he taught, the many psychologists (and others) to whom hegave such a hard time.
Rex also lives on in Beryl Curt – that extraordinary collective author, maker of mischief, singer of songs, dreamer of dreams, dancer superb,player of games, consumer of indulgences, water-pistol aficionado, snatcherof crates of wine (some of it from Open University Press – sorry Justin).
With her incredible intellectual gifts, her zest for life, with her determina-tion to make trouble and to have such fun, such fun, doing it, how couldshe not? She was Rex’s invention, and gave him so much happiness inthe last years of his life. Being acorporeal, Beryl cannot die – and will behis most lasting legacy and tribute. Long may she prosper and continueto make trouble.
And Rex will endure in the words he wrote. The words that follow are his last. I hope that despite my fiendish editing, you can get some little measure from them of just what a remarkable man he was.
Wendy Stainton RogersLong WittenhamJanuary 2000 Introduction
In terms of psychology textbooks, ‘gender’ and ‘sexuality’ are comparat-ively new kinds of language. Their use in psychology today reflects recentchanges in the way that psychology is taught, studied, researched and practised. These changes include a growing sensitivity to the politics of the discipline, which has been prompted by inputs from critical andfeminism-informed scholars. Many mainstream psychologists are stronglyresistant to the idea that psychology has any engagement with politics.
Psychology is generally assumed to be a science and, as such, outside ofpolitics. But as you will see as you progress through this book, there area number of movements both within and outwith psychology that havechallenged this claim, notably feminism, social constructionism and post-modernism. Indeed, all of these movements pose an even more extensivechallenge to science itself. They argue that science is profoundly political,not in a party politics sense, but in terms of the politics of power.
This concern with the politics of power has led to a fuller awareness of the reflexive relation between language, knowledge and power. Thistoo has been a major stimulus to the introduction of gender and sexualityinto psychology’s domain. Both of these are areas of human experienceand action in which language, knowledge and power are played out. Togive just one example, this is how one psychologist began to open up thequestion of how language and gender are connected: ‘man’ and ‘person’ have been synonymous in Western, patriarchalthought, as is evidenced by the use of the terms ‘man’, ‘mankind’,and ‘he/him’ as universals. As women we can strive to be ‘people’ and ‘women’. Logically there is no contradiction. However, because‘person’ actually consists of the attributes which are meant to be char-acteristic of men, there is an underlying contradiction.
If you want to get a sense of the point Hollway is making, go and look atalmost any psychological text that was written in the 1970s or earlier. Youwill find that it almost certainly uses the term ‘man’ to mean ‘people’, and‘he’ and ‘him’ to refer to both men and women. We were told, at the time,that this was no more than a grammatical convention. And yet, slips ofthe pen often showed that the convention worked in only a superficialway. Miller and Swift (1981) illustrate this with the following quotations: As for man, he is no different from the rest. His back aches, he rup-tures easily, his women have difficulties in childbirth.
[M]an can do several things which the animal cannot do. . . . Even-tually, his vital interests are not only life, food, access to females,etc., but also values, symbols, institutions.
Hollway is suggesting that when language like this was commonplace,women were being excluded and made to feel that they did not ‘belong’to the human race. Thus the very way that language is used is power-fully implicated in the way people perceive and think about men andwomen. And, crucially, the way people perceive and think about men andwomen affects how they treat men and women. This brings power intothe equation, since the different treatment of men and women has con-siderable consequences.
In 1972 a fascinating study was published (Broverman et al. 1972) which explored the way mental health professionals thought about men andwomen. This was interesting in itself – psychologists do not usually puttheir own thinking under scrutiny. But the results they got were even moreinstructive. They asked a large number of practising mental health pro-fessionals (both men and women) to describe the qualities of: 1 the mature, healthy, socially competent adult 2 the mature, healthy, socially competent man 3 the mature, healthy, socially competent woman.
The descriptions of the ‘mentally healthy man’ and the ‘mentally healthyadult’ were virtually identical. Both were characterized as having stronginstrumental qualities (that is, being able to do things) and some of the moredesirable expressive traits (that is, about their feelings and ways of con-necting with the social world). But the description of the ‘mentally healthywoman’ was quite different. She was characterized as more submissive, moreeasily influenced, as excitable in minor crises, concerned with her appear-ance and more likely to have her feelings hurt. She was less independent,less dominant, less aggressive, less objective and less adventurous.
These findings showed that mental health professionals equated ‘men’ with ‘adults’. Effectively, they saw them as one and the same – to be amentally healthy man is to be a mentally healthy adult. But this was nottrue of their ideas about women – to be a mentally healthy woman wasnot seen as the same as being a mentally healthy adult. Rather, for a woman to be viewed as mentally healthy, she needed to ‘feminine’. If shefailed to conform to accepted feminine qualities, then she could not be amature, healthy, socially competent woman.
It was this kind of work that forced (some) psychologists to take another look at the assumptions about the qualities of men and women –sex differences, as they were then called – that underpinned the disciplineof psychology. This in turn led to the introduction of gender as a topic,and, more generally, to the consideration of the interplay of language,knowledge and power in psychology’s approach to its subject matter –people. Once this happened, sexuality also came to be addressed as a topic.
This was because once the whole can of worms of language, knowledgeand power was opened up, then it was not just psychology’s sexism thatcame under fire, but its homophobia too. It was at about this time (aswe describe in the Introduction to Part II) that psychologists in the USAconceded that homosexuality was not a disease.
But we are getting a bit ahead of ourselves. The aim of this book is, primarily, to give you a basic introduction to the psychology of genderand sexuality as it is now pursued within what has come to be called ‘critical’ psychology (see, for example, Stainton Rogers et al. 1995; Fox and Prilleltensky 1997; Ibáñez and Íñiguez, 1997). However, to be ableto make sense of what it is that psychology is critical about, you need to have a basic grounding in the mainstream approaches that have been taken in psychology in these fields.
We have therefore divided the book up into three parts. Part I sets out the three mainstream paradigms in which psychology has researched andtheorized about gender and sexuality: biological paradigms (Chapter 1);social and cultural paradigms (Chapter 2) and interactive paradigms(Chapter 3). It needs to be said that these are still, for many psychologists(probably the majority), the ways in which they continue to be conceived.
But these paradigms are under fire from critical psychologists – in whichcamp we would place ourselves. So, as an overtly critical text, in our bookwe have included in the first three chapters some critique of the main-stream approaches, and have then set out the main challenges that havebeen directed to them (although, you will notice, our criticality pops upfrom time to time even in the first three chapters).
Part II covers the three main kinds of challenge that have been directed towards this mainstream work: liberatory challenges (Chapter 4), feministchallenges (Chapter 5) and postmodern challenges (Chapter 6). These chapters each provide a detailed account of the theory-base from whichtheir challenge is mounted, and each introduces some of the main criticismsthat have been directed towards psychology’s research and theorization.
Part III then takes a different tack. It contains five chapters on a range of different topics: research into sexual behaviour (Chapter 7), alien sex(Chapter 8), bodies (Chapter 9), sex crime (Chapter 10) and ‘new men’and ‘new women’ (Chapter 11). These chapters draw on critical – mainlyfeminist and postmodern – theorizing, and show how they can be appliedto subjects, issues and topics for which gender and sexuality are salient. Ourreason for doing this has been that feminist and postmodern theorizingcan often be quite inaccessible. All too often they are written in obscurelanguage, in which it is all too easy to get lost. By concentrating on par-ticular topics and issues, we hope we have been able to show (rather thantry to explain) what they can do, and how they do it. And, to be honest,it is a more interesting way to approach this work – well, it was for us,and we hope it will be for you too.
More specifically in Part I, Chapter 1 reviews biological paradigms, and provides a fair amount of the basic, underpinning knowledge that you needto know in relation to things such as the physiology of the body and bodyarchitecture. It contains details, for example, of what can go wrong genetic-ally in relation to ‘bodily sex’, and information about research into thebiological basis of what goes on in the body during sexual intercourse.
It also summarizes recent developments in this field, including sociobio-logy and evolutionary psychology. Chapter 2 reviews social and culturalparadigms – those that concentrate on social, social psychological andcultural influences on, for example, how children acquire their under-standing of what it means to be a boy or a girl. It is mainly based aroundpsychology, looking, for example, at social learning theory explanationsof how boys learn to behave like boys and girls to behave like girls. But it also includes important work from anthropology and sociology.
Chapter 3 examines interactive paradigms – those where psychologistshave sought to understand gender and sexuality through the interplaybetween biology and culture. These approaches cover a lot of ground,including the work of Eysenck, Freud and Kohlberg. It looks in par-ticular at theories of gender development, especially those that focus onmoral development. This was one of the first areas to receive a criticalchallenge from feminists, and the chapter ends by looking at the workof Carol Gilligan, and her claim that women approach ethical issues from‘a different voice’ from men.
In Part II we begin, in Chapter 4, by looking at the liberatory move- ment which influenced psychology in the 1960s and 1970s, especially inhumanistic psychology. The chapter leads into this through the historyof liberatory movements more generally, and includes an account of theinfluential work of Willhelm Reich. Chapter 5 sets out the basis of thefeminist challenge. A fair amount of the chapter is devoted to describingwhere and how feminist ideas emerged, and explaining the differencesbetween first wave and second wave feminism. The chapter also details themany different forms and approaches of feminism, including some of theconflicts between them. It then looks at three main challenges that feminism poses for psychology: to psychology’s epistemology, to its modes of inquiryand to theorization. The chapter explores the first two of these in somedetail. Feminist challenges to theorization are taken up in Part III.
Chapter 6 sets out the challenges presented by postmodern theorizing.
Again, we have had to adopt a fairly superficial approach, both becausethis is a wide (and growing) theoretical field and because, quite frankly,much writing in this area is at best ‘difficult’ and at worst downrightobscure and impenetrable. This is not just a matter of its theorists beingbloody-minded and deliberately cryptic, though it has to be acknow-ledged that some do seem to take a kind of mischievous pleasure in beingincomprehensible. Postmodernism is fundamentally concerned with lan-guage, and how language can be used to beguile us into seeing things inparticular ways – sometimes it talks specifically about ‘language games’.
A good example is the description given at the beginning of this sectionof the use of ‘he’ and ‘man’ as generic – as if they represent both male and female. As we hope we have shown you, they are not actually experiencedin that way, either by the people who say or write the terms or those whohear or read them. Language, according to postmodern theory, powerfullyconstructs the way people see the world, and the way they make sense oftheir experiences, of themselves and of others. Consequently, postmoderntheorists argue, it is necessary to take enormous care in the language used to ‘do’ theory. It needs to be precise, and it needs to be difficult to understand – it needs to make the listener or writer think hard about what is being said, for that is the purpose of the exercise. What we havetried to do in Chapter 6, therefore, is to outline the main elements of postmodern theory, how they apply to psychology, and, specifically, thechallenge they present to mainstream approaches to the psychology ofgender and sexuality.
At first sight, Part III might look like a bit of a ‘rag-bag’. Each chapter is on a different topic, and their approaches are different too. However,there is some purpose in all of this. We have chosen each topic because we thought it would be interesting to you. But we have also used eachone to demonstrate a particular strategy that can be used to approachthese kinds of topic from a ‘critical’ perspective. Chapter 7, ‘Where’s theaction?’, begins with mainstream research into sexual conduct – who does what, with whom and how often? It then goes back and examineswhat this research is doing: what are its consequences?, and what are the implications of the conventional way in which such research is usuallyreported? It explores the idea that science can be viewed as a ‘story-tellingpractice’, and examines why we need to be deeply suspicious, some-times, of the stories that science tells. Chapter 8, ‘Aliens and others’, makesa foray into the way in which sex and gender have been construed in science fiction in the form of ‘aliens’ (that is, beings from other planetsand dimensions). It also briefly examines how sex, sexuality and gendercan, today, be manifested and manipulated in cyberspace. Chapter 9,‘Bodies’, takes a brief and selective look at a topic which is of growing interest in psychology, and indeed in theory more broadly. It focuses, inparticular, on the ways in which warranting is used in claim-making andargument. It looks at the way in which psychologists make use of warrantsto, for example, justify their claims that people who are unhappy with theirbodies – who suffer from ‘syndromes’ and ‘conditions’ (such as anorexianervosa) – ‘need’ therapy. Chapter 10, ‘Sex crimes’, looks in particularat rape, both female and male. Here, in particular, feminist theorizationis applied to the ‘myths’ that surround these crimes (for example, thatmen are driven to rape through an excess of testosterone) and is used toexplore some of the dangers inherent in sociobiological theorizing. Finally,Chapter 11, ‘New men, new women, new relationships?’, explores howgender and sexuality are undergoing change, and the consequences forthe lives, life experiences and life opportunities of today’s young men and women.
Some ideas about how to approach the book
Our aim in this book has been to offer you something of a textbook, in thesense that we have tried to cover the ground that you need to know about,at a basic level, to ‘get into’ the psychology of gender and sexuality. Wehave also included some aids to understanding and using the book in your studies: 1 Suggestions for further reading (at the end of each chapter).
2 A glossary of key terms (these are marked in bold, and you will find the glossary at the end of the book).
3 Summary boxes (at the end of each section of Chapters 1–6).
4 Boxes summarizing ‘implications for psychology’ (at the end of Chap- As a textbook, the chapters follow a logical sequence. Part I builds up a case for a critical approach (as well as giving you a basic grounding in psychology’s conventional approaches to what we now call gender and sexuality). Part II then sets out the three main paradigms that chal-lenge the mainstream approach from a critical perspective. Part III then applies these approaches to a variety of topics. So, if you want a thoroughgrounding in this field of work, you will do best to read the chapters in Parts I and II in the sequence in which we have presented them. Thechapters in Part III are independent of each other, and can be read in anyorder. But do remember that they take up ideas and theories that have beenintroduced in the first two parts. You will get much more out of them ifyou read them after you have worked through the beginning of the book.
But, having said that, you may want to begin by ‘dipping into’ Part III– just to whet your appetite. At least it will give you some sense of whatyou are getting into.
However, you, the reader are in control now. We have done our bit.
So you can read in any order you like, and as much as or as little of the book as you want. We hope you at least sometimes enjoy it, and feelwhen you have read it that you have learned something from it. Believeit or not, we got a lot of pleasure in writing it. Certainly we learned alot in its writing – sometimes from quite unexpected sources. But that’sanother story – enjoy this one.
Part I
Mainstream psychological
approaches to gender
and sexuality
1 paradigms
Many studies have shown that there is a marked difference in how wellmen and women register and remember details, and to a man dust on ashelf or a scum ring around a bath are just that – details. Even if he doesnotice them, he may simply not accord them the importance a womandoes. To her dirt is offensive, to him it is part of the natural world. Fromvery early childhood males have a greater tolerance for, and even likingfor dirt. What a man perceives as ‘clean’ a woman might find dirty, andwhat he finds merely ‘dirty’ she might find utterly disgusting. His sense ofsmell is different too; the stale socks and sweaty shirt don’t bother himbecause they are among the pheromone-related smells that women areacutely aware of but men simply do not detect.
Recently, biological explanations of the differences between the way menand women act and see the world have become hugely popular. They argue– often very convincingly – that the reason why men are more promiscuousthan women, and why men are more aggressive and win more Nobel prizes,is that their biology is different. In this book we directly challenge suchbiological explanations of people’s social behaviour, and ask why, just now,they have such appeal. Before we can do that, though, we need to ‘beginat the beginning’ by seeing what biological explanations do have to tell usabout sex, sexuality and gender – in particular about some of the differ-ences between the sexes. This is what we will be doing in this chapter.
Psychology, the bio-social science?
From its beginning, psychology has differed from the other social sciencesin taking many of its ideas and theories directly from natural science, biology in particular. Indeed, psychology is sometimes described as a
bio-social science or even as biopsychology (see Pinel 1993), with the stress
very much on the ‘bio’. As Burr has recently argued in relation to the
nature–nurture debate:
there is a common sense assumption (which may have no factual basis)that biological factors exert a powerful ‘push’ in particular directions,and that (weaker) environmental influences have a merely moderatingeffect. Biological influences are assumed to be deeper and strongerthan societal forces, which are seen as more superficial. It is signific-ant that the study of the biological sciences has often seemed morerelevant to the education of psychologists than has sociology.
Mainstream psychology has concentrated on discovering and under-standing the biological processes through which humans came to acquirethe qualities and capacities that make them human – the biological basesof human behaviour and experience. Four main interlocked processes havebeen identified as making up these biological foundations.
The biological bases of human behaviour and
Evolution: the process through which humankind, as a species, is
seen to have originated. It is this process which is seen to have con-
stituted the basic qualities that all human beings possess.
Genetic inheritance: the process through which individuals are
seen to acquire at conception, and hence be born with, particular
qualities (such as their sex, pigmentation of skin, hair and eyes,
susceptibility to certain diseases). These qualities, being ‘wired-into-
the-genes’, are seen as largely enduring and unchangeable.
Physiology: the body’s chemical processes, through which the genes
are seen to exert their influence on human behaviour. Of particular
importance in relation to sex are the operations of hormones, which
differ (albeit in highly complex ways) between males and females.
Morphology: the processes through which body form is seen to
develop as a result of physiological influence. In terms of sex, two
aspects are particularly important. The first has to do with visible
bodily differences (including the development of genitals, breasts,
differences in height and overall body shape and size) between men
and women. The second has to do with the ‘architecture’ of the brain,
which affects cognitive performance.
This chapter looks at each of these. We begin by explaining the processesinvolved, and then we set out the biologically grounded theorization thathas been developed to explain the differences between the sexes. Given thatsome of you may not have studied biology in any depth before, we haveincluded some basic information. If you are already familiar with this material, you may find you can skip over these sections quite rapidly.
The theory of evolution
It was Darwin’s great achievement to put the ideas of evolution – ideas
that had been around for some time – on to a scientific basis. This he
achieved through his observations of the natural variety of living species.
His evolutionary theory proposes that change among living things happens
through the combination of the natural occurrence of ‘sports’ – offspring
which are different from their parents – and their subsequent struggle for
survival. Those individuals which are well adapted to their environment
tend to survive and reproduce. Those which are not tend to die before they
can reproduce, and hence their ‘blood-line’ dies out. In this way living
things adapt to their environment, generation by generation. Darwin called
this ‘natural selection’, the process by which nature selects the ‘fittest’ to
The theory of genetic inheritance
However, for all the power of Darwin’s theory of evolution, it re-mained incomplete until there was a theory about how the mechanismof biological inheritance worked. The foundational work was conductedin parallel with Darwin’s work (but in obscurity) by Gregor Mendel, a Polishmonk working in Brno, now in the Czech Republic. In the monasterygarden, between 1855 and 1868, Mendel bred different varieties of gardenpea and meticulously documented how different characteristics were passedon from one generation to the next. When this work was rediscoveredby three independent investigators in 1900 it led directly to the scienceof genetics as we know it today.
Mendel had shown that the key to inheritance lay in pairs of factors that exist in each organism, which divide before fertilization and recom-bine during fertilization. He found that these pairs of factors produce, onlarge-scale samples, a mathematically precise ratio of different physicaloutcomes at maturity. For example, he looked at peas that differ in theircolour (they can be green or yellow) and in their shape (they can be round or wrinkled). Mendel bred together yellow and green, round andwrinkled peas, and demonstrated that under carefully controlled condi-tions he could predict precisely how many round-yellow, wrinkled-yellow, round-green and wrinkled-green plants would be produced in the nextgeneration.
Genetic inheritance
This information about inherited characteristics, when rediscovered in 1900,
fitted extremely neatly into the then-current state of cytology (the study
of animal and plant cells). Cytologists had recently found out that the
nucleus of living cells contained threads of material which were intimately
involved in cell division: these were named chromosomes.
Using microscopes, cytologists found that they could, with some organisms (such as fruit flies), see each chromosome, and that they could
be sorted into pairs. Moreover, they observed that whereas in ordinary
cell division (called mitosis) each pair is simply reproduced, in the cell
division in which sperm and ova are produced (called meiosis), only one
of each pair is generated and only, therefore, a half set of chromosomes.
These sets then combine, when sperm and ovum meet at fertilization, to
produce a full set of paired chromosomes, one of each pair coming from
the sperm and one from the ovum.
Mendel’s ‘pairs of factors’ could now be identified with chromosomes.
These factors were called genes, although it was not until later that the
mechanisms by which genes work was discovered. In 1944 Avery, MacLeod
and McCarty identified the active agent as a nucleic acid, but it took
until 1953 for the full picture to emerge through the research of Watson
and Crick. They identified the molecular architecture of how genes func-
tion. They were able to show that genetic material (called DNA, short
for deoxyribonucleic acid) consists of a spiral structure (usually called a
‘double helix’) rather like a ladder that has been twisted. The ‘sides’ of
the ladder are made of long molecules of sugars and phosphates, and the
‘rungs’ are made up of pairs of interlocking nitrogenous bases: adenine,
cytosine, thiamine and guanine.
Since only adenine will fit with thiamine (and vice versa), and only cytosine will fit with guanine (and vice versa), when the ‘ladder’ is split (as happens when cells divide), each side can act as a template for theexact production of the other side. In this way, through the sequence-patterns of the bases along the sugar-phosphate strands of the DNA, information is stored in chemical form (in a manner that is similar to the way computers store information electronically). This information islike a series of computer programs, which enable and regulate the pro-cesses by which living organisms develop and operate. In simple terms,they work chemically. They provide blueprints for, say, constructing the precise form of various body organs – the colour of your eyes, yourskin colour, whether your hair is naturally curly or straight, your heightand whether or not your ears stick out or your nose turns up. Equally,they provide the operating codes for digesting food, eliminating waste,breathing and so on.
The process of producing females and males
Humans generally have 46 chromosomes. Forty-four of these can be organized into 22 homologous pairs (look-alike couplets) of chromosomes.
However, the other two come in two distinctive configurations: either anXX set or an XY set (this nomenclature reflects their alternative shapes,like an X and like a Y). In most instances, people possessing an XX pairare female; people possessing an XY pair are male.
This genetic distinction now allows an alternative definition of sex to the traditional obvious observational means (boys are born with a penis,
girls with a vagina) and is called chromosomal sex. It is on this basis, for
example, that ‘sex testing’ is carried out when there is a dispute about an
athlete’s sex. The configurations arise through the half-set of chromosomes
from each parent. Females produce only X chromosomes in their ova;
males produce about half X-carrying and half Y-carrying sperm. Where an
X chromosome from the male meets the X chromosome from the female,
the resulting foetus is female. Where a Y chromosome is in the sperm
that fertilizes the egg, the result is a male foetus.
Once an egg is fertilized it begins to divide to produce more cells. First a hollow ball of cells develops, and soon this begins to fold and
differentiate to construct an embryo. For the first six weeks or so of
development, male and female embryos are the same – except at the
genetic level. At this point both have the capacity to develop into either
a boy-form or a girl-form, since both build up two structures: one with
the capacity to generate a male reproductive system (called the Wolffian
); one with the capacity to generate a female reproductive system
(called the Müllerian system). But at around the third month, things begin
to change.
Where the embryo has an XY (male) pairing of sex chromosomes, two kinds of hormones (see below) are produced. One stimulates the Wolffianmale-reproductive-system-to-be, to make it begin to grow, and, at the sametime, the other inhibits the Müllerian female-reproductive-system-to-be,to make it degenerate. Where the embryo has an XX (female) pairing ofsex chromosomes, there is hardly any secretion of hormones to controlthe production of the girl’s reproductive system, and it is the Müllerianfemale-reproductive-system-to-be which develops. Biologically speaking,femaleness is the default state – an embryo develops a female reproduct-ive system unless it is masculinized by hormonal action.
Sex differences and physiology
The genetic differences between men and women are made manifest by the action of hormones, which result in differences in physiology. We will look at hormones first, and then examine other physiological sex differences.
Hormones are sometimes called ‘chemical messengers’ – this gives a
good clue as to what they are and what they do: they are chemicals
which are produced by endocrine glands (endocrine glands secrete
into the body, as opposed to exocrine glands that secrete out) and travel around the body in the bloodstream. Particular organsin the body are receptive to particular hormones – they possess a biochemical receptor site which, when activated by a hormone, ‘turns on’ or ‘turns off’ a particular process. You have just met anexample of a hormone working in this way, where hormonal actioncauses the male reproductive system to develop.
The hormonal system is controlled largely by a gland in the brain, the
pituitary gland. This gland produces a number of hormones, which, in
turn, stimulate the release of other hormones. For example, the action
of the pituitary stimulates the sex organs (called gonads – the testes and
the ovaries) to secrete gonadal hormones. The action of the pituitary is
affected by a nearby brain structure – the hypothalamus – which pro-
duces hormones that trigger the pituitary into action. Hormones control
a large number of body processes. One that you may know already is
adrenaline, which is produced in response to arousal (for example, being
frightened or excited). The impact of adrenaline is to ‘prime’ the body
to take action (to fight, or to run away, say, from danger) by making the
heart beat faster and moving the blood supply to where it is needed to
take swift action. But here we are interested in sex hormones (sometimes
called gonadal hormones).
Sex hormones
Sex hormones can be divided into two main classes: androgens and
oestrogens. It is often assumed that androgens are ‘male hormones’ and
oestrogens are ‘female hormones’, as if only men have androgens and only
women have oestrogens. But this is not so – both sexes produce both
types. What is true is that, in general, men have more androgens and fewer
oestrogens operating in their bodies; and women have more oestrogens
and fewer androgens. The most common of the androgens is testosterone,
and the most common oestrogen is oestradiol. The gonads also secrete
a third type of hormone, the progestins, the most common of which is
progesterone. Progesterone’s main function is to prepare a woman’s body
for pregnancy following fertilization, although men also secrete it in small
quantities (its function for them is, as yet, uncertain).
Hormones and puberty
During infancy and childhood, the level of sex hormones circulating in
the body is low. But at puberty a number of hormones come into play.
The pituitary releases growth hormones, which results in the adolescent
growth spurt
, when bones (especially the long bones in legs and arms) and
muscles fairly suddenly begin to grow faster, so that the child relatively
rapidly gains adult size and proportions. The pituitary also releases two
other hormones: follicle-stimulating hormone (FSH) and luteinizing
(LH). These stimulate the gonads to increase the production of
oestrogens and androgens, which results in the maturation of the gonads
and the development of secondary sexual characteristics – body hair in both
sexes, and the distinctive body shapes of adult females and males.
In adolescent boys and in men the production of androgens is pro- portionately higher than their production of oestrogens; in adolescent girlsand women the situation is reversed, with relatively more oestrogens andfewer androgens being produced. Again, it is important not to assume thatandrogens are simply ‘male hormones’ and oestrogens ‘female hormones’,since one of the androgens, for example, is responsible for the growth ofpubic and underarm hair in both boys and girls. Equally, FSH and LHare involved in both the development of eggs (ova) in women and theproduction of sperm in men, and LH contributes to the maturation ofthe egg in women and the maturation of sperm and the production oftestosterone in men. From puberty onwards, throughout their fertile years,women’s hormones operate cyclically – they have a cycle of fertility, whichpasses through a sequence of stages controlled by hormones (this isdescribed in more detail later). In boys the production of hormones isnot cyclical, but neither is it entirely steady.
Hormones and sexual activity
In animals, sex hormones are often clearly linked to sexual activity. Inmany mammalian species females are sexually receptive only at certain Biology is not destiny
This certainly seems true in relation to decline in hormone levels.
For example, many women experience an increase in sexual inter- est after the menopause, even though their oestrogen levels will be much lower. This is assumed to be much more to do with no longerhaving to worry about pregnancy or contraception than having anything to do with hormone levels. And it is worth noting that itis a lot easier to have an active sex life in an ‘empty nest’ than onefull of teenage children.
points in their cycle of fertility – they are sexually receptive only when‘primed’ by their homones. But in humans the relationship is much morecomplex. It seems that puberty is an important trigger for developing anappetite for sex; individuals who do not undergo the hormonal changesthat result in puberty generally fail to engage in sexual relationships (Meyer-Bahlburg 1980). But this is not sufficient in itself, and hormonesare certainly not the only factor (nor even, probably, the most importantfactor) in determining whether an individual human becomes interestedin sex or is sexually active.
Problems with sexual differentiation
The way in which sex unfolds in the embryo is a complex process. Thedescription provided earlier simplifies it a lot. Researchers have gainedsome understanding of how it works by looking at what happens whenthere are problems with the process. The reproduction of chromosomesdoes not always work perfectly, and the consequence may be that thereare, in effect, ‘bugs’ in the ‘program’ encoded in the DNA. These origin-ally arise spontaneously, although some get reproduced and passed on(leading to certain inherited dysfunctions, such as haemophilia). Manysuch spontaneous errors are so harmful that the foetus dies (or may neverdevelop beyond a few cells) and is either reabsorbed or is miscarried (thetechnical term is a spontaneous abortion). Other errors may be so trivialas to be unnoticed. In the middle range lie a number of conditions, someof which have an effect on the new individual’s sex-linked architecture.
When the chromosomes differ from the norm, this leads to dysfunctionsin the usual hormonal system, which can lead to problems in sexual differ-entiation. So too can hormonal factors alone. Some of the main syndromesassociated with these are set out in Box 1.4.
Genetic and hormonal syndromes which affect
sexual architecture
Klinefelter’s syndrome is the most common sex chromosome mis-
configuration, occurring in about 2 per 1000 male births. It results
from having one or more extra chromosomes – 47 or more instead
of the usual 46. An extra X chromosome, making an XXY con-
figuration, disturbs male physiology. Although individuals with this
syndrome have male internal and external genitalia, their testes are
small and cannot produce sperm, so they are infertile and have a
lowered libido. Boys may also develop a more female body shape
at puberty. Like other people with extra chromosomal material, males
with this syndrome are more likely to have a learning disability.
Occasionally there are even more extra chromosomes – XXXY andXXXXY configurations have been found. Such individuals often havemore severe problems with their reproductive and skeletal systems,and a higher probability of severe learning disability.
‘Super Males’ is where an XYY pattern is found, which usually leads
to the male being taller and also raises the possibility of learning
disability. This pattern has been subject to a great deal of publicity,
with claims being made that such people are ‘super-males’ with strong
aggressive tendencies, based on the finding that such men are relat-
ively more likely to end up in prison. However, Witkin et al. (1976)
have refuted this claim, showing that prison inmates with an XYYpattern were no more violent than other inmates. They suggestedthat the effect is a result of the men’s learning disability and greatheight (which, in making them distinctive, means that they are morelikely to be caught committing crimes).
Turner’s syndrome is rarer, found in about 1 in 10,000 female births.
Here an X sex chromosome is missing from its couplet and this is
usually denoted as XO (O = absence). Many embryos with this
configuration are spontaneously aborted (Mittwoch 1973) but some
are not. Typically, the external genitalia are female in form but
internally the ovaries fail to form. Hence, ovulation is absent and
there are no ovarian hormones to trigger puberty – although this
can be treated with hormone supplements. Without ovaries women
with this syndrome are infertile.
‘Super Females’. Occasionally females are born with one or more
extra X chromosomes. They are more likely to have a learning
disability and some have menstrual irregularities and are sterile.
But there have been cases of women with an XXX configuration
having children (Mittwoch 1973). Again, there are a few rare cases
of women having XXXX and even XXXXX patterns, and these are
usually associated with severe developmental problems and serious
learning disability.
Intersexuality (sometimes called hermaphroditism) is where a person
is born with characteristics of both sexes. It is extremely rare,
with no more than 60 cases being identified in Europe and North
America in the past 100 years (Money 1986). It occurs when an
individual has, say, an ovary on one side of the body and a testicle
on the other, or where both tissues combine together to produce a
structure called an oveotestis.
Pseudohermaphroditism occurs much more frequently. It can arise
from a variety of genetic ‘bugs’, the most common being androgen
insensitivity syndrome, androgenital syndrome and kwolu-aatmwol.
Androgen insensitivity syndrome. Here the chromosomal struc-
ture shows the usual 46-chromosome, XY male pattern. However,
the androgen receptors in the body do not recognize the circulating
androgens: they are there, but, as far as the body is concerned, when
the foetus is in the uterus, they are not – so the foetus develops, by
default, as a female. The outcome is a baby with an XY (i.e. male)
chromosome pattern, but without the corresponding male gen-
italia. The baby looks female and is identified as a girl at birth. The
Müllerian system does not develop. Interestingly, their (internal) testesproduce enough oestrogen to stimulate breast development atpuberty, but insensitivity to the androgen that mediates underarmand pubic hair in both sexes means that this hair does not grow.
Individuals with this syndrome are infertile and do not menstruate.
Adrenogenital syndrome can affect both XX and XY foetuses. It
results from a reduction in adrenal cortisol (hydrocortisone),
which in turn leads to an increase in adrenal androgens (male
hormones). For boys the main impact is an accelerated onset of
puberty, but, other than this, males with this condition experience
few problems. In females, however, the excess of androgens leads
to a masculinization of the body – an enlarged clitoris at birth (which
may look like a penis) and the development of a sac resembling a
scrotum. Confusions as to the sex of an infant have occurred, but
these days early surgical ‘correction’ is used and with oral cortisol
given in childhood typical adolescent development follows. The
internal sex organs are usually unaffected.
Kwolu-aatmwol is the New Guinea name given to a form of pseu-
dohermaphroditism which is found there and in the Dominican
Republic. It means ‘female thing-transforming-into-male thing’ and
arises through a genetic disorder arising from a deficiency in the enzyme
5-alpha ructase, which prevents testosterone from producing the usual
male genitalia at the foetal stage of development. Individuals born
with this condition have genitals that are ambiguous – their penis
looks more like a clitoris and their scrotum is unfused and looks
like labia (Herdt 1990). Often such individuals are raised as girls,
although they are genetically XY. At puberty they produce testos-
terone and become masculinized. Their penis grows, their testes
descend, they grow facial hair and their musculature takes on a male
shape. Such individuals seem to transform from girl children into
men as they become adult.
These and other conditions are sometimes regarded as ‘natural experi-ments’. They have been studied by psychologists to explore issues aboutthe development of gender identity, sexual orientation and ‘normal’ sexualdevelopment.
Hormones and menstruation
One of the most important functions of hormones in adult women, once
they begin to ovulate and until the menopause, is the control of their cycle
of fertility: the (about) monthly production of an ovum and the prepara-
tion of the uterus for pregnancy if that ovum is fertilized.
The cycle of fertility
ovarian follicles to grow around one or moreova.
The follicles begin to release oestrogens, suchas oestradiol.
These oestrogens stimulate the hypothalamusto increase the production of LH and FSHfrom the pituitary.
In response to the LH surge, one or more ofthe follicles ruptures and releases the ovum.
The ovum is moved into the Fallopian tube.
Progesterone levels begin to increase.
Luteal phase
Generally the ovum is not fertilized and pro-gesterone and oestradiol levels begin to fall.
The walls of the uterus are sloughed off as Premenstrual syndrome
In the 1960s Dalton (see Parlee 1973 for a review) first suggested that
women experience a variety of negative emotional, cognitive and physical
effects as a result of the hormonal changes that precede menstruation –
what became known as the premenstrual syndrome (PMS). The list of
symptoms associated with this syndrome extends to more than 150, includ-
ing headache, backache, abdominal bloating, irritability, depression and
tension. Blechman et al. (1988) reviewed the various symptoms and con-
cluded that they are far too diverse to constitute a ‘syndrome’. None theless, throughout the 1960s and 1970s many studies were reported whichclaimed to find evidence for ‘moodiness’ associated with the menstrualcycle: women typically showing heightened feelings of wellbeing aroundovulation, and feelings of depression, tension and irritability during theperiod just before and during menstruation. These effects have beenattributed to the hormonal changes associated with the cycle of fertilitydescribed previously.
Research evidence
Although excess oestrogen, falling progesterone and oestrogen/progesteroneimbalance have all been proposed as possible causes of negative mood,no clear evidence has been found for any link between any of these hormone levels and reports of mood effects (see Rubin et al. 1981, for a review). Studies that claim to show systematic mood changes in relationto different phases in the cycle have been heavily criticized for their poormethodology.
McFarlane et al. (1988) conducted a detailed, lengthy and methodo- logically sophisticated study to try to address these problems. For example,they told participants that they were looking at ‘mood changes over time’rather than that it was a study of ‘premenstrual syndrome effects’; they usedinstruments to measure mood which did not prime negative responses;and they included women who had normal cycles, women taking oralcontraception and men in the study. Their main result was that all par-ticipants in the study experienced mood swings from one day to anotherand, indeed, over a day.
But there were no systematic effects on mood as reported in a daily diary which were different for the three groups, except just one – the womenwith normal cycles reported more pleasant moods during and immediatelyafter their periods. McFarlane et al. also asked participants to report on their moods retrospectively. They filled in a questionnaire about their moodsat the end of the 70 days over which the study took place. Interestingly,their responses here did show a PMS effect in women’s recollections oftheir moods. Women reported in this questionnaire that they had had PMS-linked ‘moodiness’, even though this was inconsistent with the diaryentries they had made at the time. The most significant mood effect foundin the whole study was to do with a weekly cycle – generally all groupsreported more negative moods on Mondays and more positive moods onFridays (perhaps this should be called the TGIF syndrome).
Slade (1984) also found no associations between mood and cycle of fertility, although she did find that pain and fluid retention were morecommon in the premenstrual and menstrual phases. Blechman et al. (1988) suggest that these physical symptoms, together with apprehension aboutthem, may well be the basis for women seeing themselves as ‘feeling pre-menstrual’, rather than any hormonal effect.
Testosterone and aggression
In many animal species testosterone has been shown to play an activerole in aggressive behaviour (Kalat 1992). Its effects in humans, however,are less clear. Although press reports of studies conducted on the possiblelink have generally made unequivocal claims – Goleman, writing in the NewYork Times, for example, entitled his piece ‘Aggression in men: hormone levels are the key’ (Goleman 1990) – academic commentators are usuallymuch more circumspect. Brannon (1996), for instance, summarizes thesituation thus: researchers have used different approaches to investigate the actionsof testosterone on various behaviours and the reaction of testosteroneto various experiences. All of the studies found some relationshipbetween testosterone and behaviour, but the relationships were verycomplex. Research on human subjects does not confirm a clearcause-and-effect relationship between hormone levels and aggressivebehaviours.
This complexity is evident, for example, in a number of studies carried outby Dabbs and his colleagues. One study produced what seem at first sightto be fairly clear-cut results. It examined testosterone levels in militaryveterans (Dabbs and Morris 1990). The men whose testosterone levelswere in the top 10 per cent of the 4462 tested were found, comparedwith the rest of the sample, to more often report: having trouble with parents, teachers and classmates; being assault-ive towards other adults; going AWOL in the military; and using hard drugs, marijuana and alcohol. They also reported having more sexual partners. The overall picture is one of delinquency, substanceabuse, and a general tendency towards excessive behaviour.
But these results were not as clear-cut as this assertion implies. The dataobtained showed an interaction with socio-economic status. Men withhigher income and more education were, on average, significantly less likelyto have high levels of circulating testosterone than men with low incomeand less education. Only in those men with lower socio-economic statuswas there a tendency for high levels of testosterone to be linked to anti-social behaviour. These data can be interpreted in many different ways.
Dabbs and Morris concluded that high-status men learn to cope with theirantisocial behaviours in a way that low-status men do not. But Brannon(1996) points out that high-status men could, just as easily, simply be ina position not to get into trouble. As soon as an attempt is made to teaseout cause-and-effect, interpretation gets very difficult.
Dabbs and his colleagues (Dabbs et al. 1988) have also studied testosterone in women, looking at samples of prison inmates and collegestudents. They found that among the prison sample, women with the high-est levels of testosterone were more likely to have records of unprovokedviolence, whereas those who were serving sentences for defensive violence(such as murdering an abusive partner or spouse) had the lowest levelsof testosterone. But the average levels of testosterone were the same forthe prison and student samples. Again, these data can be interpreted ina number of different ways, requiring consideration of social and culturalfactors as mediators of biology.
Possibly the data from Dabbs and his colleagues that are the most difficult to interpret (Dabbs et al. 1990) are from a study looking at male testosterone levels in relation to different professions. They found thatthe highest average levels of testosterone were found in football playersand actors, and the lowest in church ministers. Salesmen and firefighters,who they assumed would have high testosterone levels, did not have highlevels. The researchers’ attempts to account for the patterns they foundbegin to look more and more confused: ‘ministers tend to be self-effacingand actors self-aggrandising. Ministers praise the glory of God, whereasactors keep the glory to themselves’ (Dabbs et al. 1990: 1264).
Other sex differences in physiology
The hormonal differences between males and females lead to differentdevelopment at puberty. Boys’ bodies develop more muscle and less fatthan girls’ bodies. The average male body has 15 per cent fat, whereasthe average female body has 27 per cent fat. In men about 40 per centof body weight consists of muscle; in women it is 23 per cent. Men alsotend to have a higher metabolic rate – they ‘burn’ more calories whetherthey are just resting or taking exercise. One consequence is that men usually find it easier than women to lose weight. For men, exercise alonecan result in weight loss, whereas women usually need to reduce theirfood intake as well (Meijer et al. 1991; Gleim 1993). The higher level of androgens circulating in the male body also leads to differences in metabolism. For example, men have higher levels of protein synthesis,and hence need more protein in their diet (Phillips et al. 1993).
This difference in physiology may contribute to men’s greater susceptibil- ity to a number of diseases, including, for example, cardio-vascular disease(CVD) and cancer. Men have higher mortality than females across thelifespan (Strickland 1988). This has been true for at least the past century,and the pattern is found worldwide. However, once more, it is difficultto tease out what may be biological from other influences. For example,stress is a risk factor for cardio-vascular disease (CVD), and men are muchmore likely to die from this cause than women, especially between theages of 35 to 75. But how far is this a matter of straight physiology (whensubjected to stress, males tend to release more adrenaline than females,and adrenaline raises blood pressure and heart rate)? And how much isit to do with lifestyle and gender roles? Helgeson (1990) found that menwere more likely than women to respond to stress in ways that are dysfunctional (that is, are risk factors for CVD).
Summary box
Do hormones affect human behaviour?
Although there is a body of research evidence to show that hormoneshave a direct and significant impact on the behaviour of lower (that is,lower in an evolutionary sense) animals, the evidence for their influenceon human behaviour is much less clear.
• There is good research evidence that a lack of sex hormones at puberty interferes with the acquisition of a desire for sex. It seemsthat hormones are required to trigger human sexuality, in the senseof making people want to have sex.
• Sex hormones also clearly have a direct influence on physiology, and, through this, on morphology too. This means that male and femalebodies are differently shaped (although there is an enormous rangein both male and female body forms) and work somewhat differ-ently at a biological level. These physiological and morphological dif-ferences can have an impact on behaviour. For example, they maylead to men and women using different strategies for losing weight.
• More subtle aspects of human sexuality seem to be mediated more by social and cultural influences than by hormones. Researchevidence indicates that all sorts of factors come into play, includingexpectations (for instance, in relation to premenstrual syndrome), worries (such as concern about becoming pregnant), opportunities (such as when it is possible to have spontaneous sex) and social class(which affects, for example, the likelihood of getting into trouble formisbehaviour).
Sex differences in brain architecture
As we saw earlier, men’s and women’s bodies typically possess distinguish-ing characteristics (you probably don’t need us to tell you that!). Mentend to be taller and heavier, although there is considerable diversity. Otherobvious morphological divergencies are the distinctive genitals of each sex,and the different patterns of breast development, body-hair and hair-loss.
What are less obvious are differences in the architecture of the brain.
From the subject’s beginning, psychologists have claimed that there aredifferences between men’s and women’s brains. At first their claims simplymirrored popular ‘wisdom’ of the time – women were seen as intellectu-ally inferior to men and as having brains unsuited to scholarship (althoughsuch claims did not go unchallenged at the time; see Shields 1975, andLewin 1984b for reviews). At first the arguments for difference were basedon the observation that women’s brains tend to be smaller than men’s.
It took until the late 1960s before researchers began to examine the pos-sibility that the brains of men and women might be organized differently,with the first support provided by a study conducted on rats by Raismanand Field (1971).
Much of the work in respect to human brains has concentrated on differences in lateralization. The cerebral cortex of the brain is divided
into two halves – two hemispheres – joined by a large bundle of nerves,
the corpus callosum. In adult humans each hemisphere has developed
a specialist function. Typically (the pattern is somewhat different for
left-handers) the left hemisphere specializes in language skills, and the
right hemisphere specializes in spatial skills. This was first discovered by
examining the effects of strokes (a stroke to the left hemisphere tends
to interfere with language, whereas one to the right hemisphere tends to
interfere with skills involving spatial relationships).
Research data point to the possibility that men are more lateralized than women: the specialization of each hemisphere is more complete. Forexample, Shaywitz et al. (1995) used magnetic resonance imaging (MRI) to map neurological activity in the brain while men and women were solvingverbal problems. In all of the men in the study, only the left hemisphere wasseen to be active when working on these problems. The women, however,seemed to be using both hemispheres. They concluded that: ‘Our data pro-vide clear evidence for a sex difference in the functional organization ofthe brain for language. . . . We have demonstrated remarkable differences. . . between normal males and females’ (Shaywitz et al. 1995: x).
This difference is consistent with the observation that women are much less likely than men to experience speech deficits following a left hemispherestroke (see Springer and Deutsch 1989). Brannon (1996), however, pointsout that the magnitude of the difference is limited, and many studies havefailed to find it. It would seem, she suggests, that the differences in later-alization are small but real. Different theories have been proposed to explain how the difference comes about. Waber (1976) suggests that it arisesbecause girls tend to mature faster than boys. Geschwind and Galaburda(1987) propose that it is produced by the extra testosterone circulatingin the male foetus before birth, which slows down the growth of the lefthemisphere, allowing the right hemisphere to develop faster. Kimura (1992)has questioned whether women are less lateralized, and suggested, instead,that the difference has more to do with the organization of the languagecentres in the front and back of the cerebral cortex.
Other work has explored the possibilities of sex differences in other parts of the brain, including the hypothalamus, the thalamus and the corpus
callosum. Again, studies on rats led the way, with the discovery in the 1970s
that a small area of the hypothalamus, called the sexually dimorphic
, is much larger in males than in females (see Gorski 1987 for a
review of these studies). Evidence for a similar difference in humans has
been claimed by Swaab and Fliers (1985). This area is very sensitive to
testosterone and oestrogens, and in rats it is associated with sexual response
and mating behaviour. Swaab (quoted in Gibbons 1991) has suggested that
the operation of this structure might be involved in the development of
male identity. However this claim is controversial. Brannon (1996), for
example, points out that ‘gender identity is a complex concept relating to
feelings . . . that are not limited to or congruent with sexual behaviour’
(1996: 81) and concludes that we simply do not know what this structure
does or how it works in humans.
Even more controversial is a claim by LeVay (1991) that there are struc- tural differences between the brains of male homosexuals and hetero-
sexuals; that, in effect, homosexuality is a genetic predisposition – or, as
popularly expressed, that there is a ‘gay gene’. Comparing autopsies on brains
of heterosexual men, homosexual men and women, he found that another
area of the brain (the interstitial nuclei of the hypothalamus) was twice as
large in the heterosexual men compared with both the homosexual men
and the women. But there may be other explanations for the difference. All
of the homosexual men that LeVay studied died of AIDS-related illnesses,
whereas less than half of the heterosexual men had died of AIDS, and only
one of the women. So the difference may reflect, in part at least, differ-
ential damage related to AIDS. A number of other differences have been
claimed, but evidence for them is generally fairly weak, often taken from
quite small samples (see Brannon 1996 for a fuller review of these data).
Differences in mental capacities
As mentioned at the beginning of this section, historically, psychologystarted from the preconception that men are more intelligent than women.
Yet one of the earliest intelligence tests devised by psychologists had to be‘modified’ to make sure that men scored, on average, the same as women.
Otherwise, the average scores for women proved higher than the averagescores for men. This ‘adjustment’ was still going on in the 1950s and 1960s in the UK, to make sure that as many boys as girls ‘passed’ the 11+ test(the test used to select pupils for grammar schools).
What gradually became apparent, as tests were made more sophisticated, was that women and girls consistently scored higher, on average, on tests ofverbal intelligence, and men and boys scored higher on tests of mathemat-ical and spatial ability (see Maccoby and Jacklin 1974 for a review). Morerecent work suggests, however, that the difference in verbal skills is morecomplex than was first thought, and the differences seem to be lesseningover time. Brannon (1996) suggests that the difference is small, and showsup only in some verbal abilities (such as spelling) and not in others (such asverbal reasoning). Equally, recent work on mathematical ability indicatesa much more complicated picture than was originally apparent. Boys’ andmen’s advantage is concentrated in mathematical skills that involve spatialreasoning. On spatial tasks, men and boys seem to have a consistent, butsmall, advantage over women and girls in just some skills (Kimura 1992).
Overall, Hyde (1981), using a more sophisticated form of statistical analysis than used in other studies, suggests that only about 1 per centof variability in performance on aptitude tests can be attributed to sex,with 99 per cent a result of a complex mix of other factors. However,she points out, it is impossible to tease out what may be the contribu-tion of biology (that is, arising from differences in brain architecture andphysiology) and what may be due to a host of other influences – such asdifferent expectations, experiences and interests – all of which are sociallyand culturally mediated. We will come back to this issue in Chapter 2.
Summary box
Do men and women have different brains?
• The research evidence suggests that there are some small differences in the way men’s and women’s brains are organized, leading to small average differences in their mental function. At least some ofthis may well be a result of biological differences, particularly as theyaffect the development of the brain in infancy and early childhood.
The process of lateralization seems to progress slightly differently inmen and women.
• As a consequence, women tend, on average, to show a small superi- ority in language skills, and men in spatial skills.
• However, these differences are small. They cannot be used to account for much greater differences in men’s and woman’s performance –for example, that there are many more male than female mathemat-ical ‘geniuses’. Social and cultural factors play a significant part. Associal attitudes and expectations change, and as girls gain greater opportunities to engage in ‘male’ subjects (such as mathematics andengineering) during their education, these performative differencesseem to be getting less and less.
The sexual response
In 1966 Masters and Johnson published Human Sexual Response. This work addressed the physiological features of sexual arousal and sexualactivity. The people who took part in the studies (382 women and 312 men)were volunteers and mostly married couples. More than 10,000 sexualresponses were examined, including sexual intercourse, masturbationand ‘artificial coition’ (self-stimulation using instruments that allowed directviewing and film recording). From this work Masters and Johnson wenton to develop a model of sexual response divided into four phases: theexcitement phase, the plateau phase, orgasm, and the resolution phase.
It is usually accepted that these different components of the sexual response are biologically pre-programmed – they do not need to belearned and happen automatically given the right stimulation. It is not Masters and Johnson’s four stages of sexual response
Excitement. The first biological indicator of sexual excitement
in women is vaginal lubrication, which typically appears within
30 seconds of stimulation. This, Masters and Johnson discovered,
is exuded from the semi-permeable vaginal walls in response to an
increase in blood supply. In men, erection can be even faster – but
also much slower. Erection also results (mechanically speaking) from
an increase in blood supply. Both sexes show genital engorgement
and both also experience patterns of muscle contraction. Women
also show erectile responses both in the clitoris and of the nipples.
Changes also occur in the two sets of genital lips (the major and
minor labia) yielding a blooming effect, and the vaginal barrel begins
to oscillate with distensions exceeding constrictions: its inner two-
thirds can increase in diameter by 300 per cent. In men the scro-
tum is raised and the spermatic cords shorten. Both sexes (women
much more often than men) can show a ‘sex flush’ or rash (which,
unlike blushing, begins on the abdomen).
The plateau phase covers some further changes that follow excite-
ment (for example, raised pulse rate) which can be regarded as
precursors to any subsequent orgasm. This phase is more marked
in women than in men. The most remarkable is the ‘orgasmic
platform’ – the swelling of the lower vagina, reducing its diameter
and increasing its penile ‘grip’. In parallel the clitoris retracts and
is lifted away from the vaginal entrance. In men the testes enlarge
and are pulled further into the scrotum. When they are fully elevated
the man is on the verge of orgasm.
The orgasm. If they climax, women experience marked, fast,
rhythmic contractions of the lower vagina, gradually reducing in
intensity and increasing in interval. The uterus and sometimes the
anal sphincter also join in these contractions. In men, the sperm which
have moved into the seminal vesicles and ampullae are expelled by
contractions into the urethra. Simultaneously, the prostate gland
spasms, releasing prostatic fluid. This mixture is held in the urethral
bulb. Ejaculation results from contractions of the penis and urethral
bulb. Pulse rate and blood pressure peak during orgasm and
breathing becomes panting. Some quite extreme muscle spasms
and facial grimacing are commonplace. Subjectively, sensations of
orgasm tend to slightly precede contractions in women and ejacu-
lation in men.
The resolution phase. Within a few seconds of the end of orgasm,
the body begins to return to ‘normal’, although some signs (for
example, partial penile erection) take longer to subside. Men show
a ‘refractory period’ of between a few minutes and hours before re-
arousal is possible. Many women do not have a ‘refractory period’
and can re-orgasm rapidly. Some may manage quite a number, the
‘multi-orgasmic response’.
surprising that, at a physiological level, sexual response should tap into pre-programmed patterns, given how crucial it is to evolutionary survival. However, as the recent massive sales of the erection-inducingdrug Viagra have shown, even here instinct is by no means the wholestory. The enormous interest in the drug shows that many men feel that they have problems in getting a satisfactory erection. Although this can be a consequence of medical disorders and the side-effects of some forms of medical treatment, erection is notoriously sensitive to social andsituational factors. Some men, for example, cannot be aroused except in particular ways – for example, by viewing certain erotic stimuli, such asbondage.
Equally, for women, although the machinery for sexual response may be in working order, biologically speaking, being turned on (and henceable to respond) has much more to do with non-biological factors. Andalthough it is often assumed that women’s arousal is much more depend-ent on emotional stimuli than it is for men, the evidence for this is largelyanecdotal. Certainly, women as well as men can become fixated (that is,dependent for sexual arousal) on particular stimuli – as evidenced by thematerial available on the internet. One website, for example, is devotedto a woman who gains sexual satisfaction from having fish hooks insertedinto her breasts.
Summary box
Biology and sexual arousal
As with other aspects of human sexuality, people’s sexual response
seems to have a clear biological foundation. It appears to be a bio-
logical mechanism which, once triggered, goes through a sequence of
genetically programmed stages of response. However, given the human
qualities that people possess, this mechanism does not operate in
any simple way. It is highly mediated by expectations and experience.
A good example is ‘performance anxiety’ in men. Men who have had
sexual encounters in the past where they have failed to achieve an
erection or have lost it during sex often can become anxious during sex,
and this anxiety affects their ability to achieve or maintain erection.
This can become problematic, since the more it happens, the likelier
it is to go on happening. The good news is, however, that the cycle
can be broken, either through formal therapy or by simply finding a
sympathetic partner who is able to help them overcome the anxiety.
Equally women can develop aversion to sex following bad experiences,
which can stop them becoming sexually aroused and hence prevent
them from being able to engage in and enjoy sex. At its most extreme
this can lead to vaginismus – a conditioned response (see Chapter
3) in which the vagina clenches up when any attempt is tried to make
her sexually aroused. This makes penetration impossible. Again the good
news is that this response is reversible, once more either through
therapy or finding a sympathetic and caring partner to help her over-
come her anxiety.
Sociobiology and evolutionary psychology
In this section we will look briefly at more recent theorization which hasexpanded the kinds of behaviours considered to be biologically driven:sociobiology and evolutionary psychology.
Sexual reproduction itself is a key driver of evolution. As Gribbin andGribbin neatly state, ‘[i]n everyday language, sex speeds up evolution’(1998: 250). It is sexual reproduction that creates the genetic variabilitythat enables change. The crucial implication of this for psychology hasbeen that evolution has come to be seen as encompassing wider aspectsof sexual behaviour. Darwin himself made this connection: Sexual Selection . . . depends, not on a struggle for existence in relation to other organic beings or to external conditions, but on astruggle between the individuals of one sex, generally the males, for The rationale for suggesting that sexual behaviour is a feature of evolu-tion is that it is reproduction that is what really matters for evolutionarysurvival – it is the only way for an inherited characteristic to be passed from one generation to the next. Thus evolution favours those organismsthat get to reproduce, and whose offspring themselves get to reproduce.
In other words, having sex which results in the birth of offspring is thesole way of achieving evolutionary ‘success’. Living things have evolved awide range of different instinctual behaviours to optimize reproduction. Inthis sense, sex really is about ‘the birds and the bees’ – think, for example,of the ‘courtship display’ of the male peacock. It is not surprising, then,that a number of theories have been developed about the ways in whichhuman instinct may be involved. These theories propose that there are‘natural’ differences in the behaviour of men and women that are relatedto giving each sex a potential evolutionary advantage over others of thesame sex.
This idea has been neatly encapsulated in the term ‘selfish genes’ (Dawkins 1976), within a development of evolutionary theory called socio-biology. Its theorization proposes that organisms are predisposed, becauseof the force of evolution, to behave in ways that increase the probabilityof producing offspring, and to maximize the number of offspring produced.
Sociobiologists (such as Dawkins 1976, 1982, 1988; and Wilson 1980)have argued that this leads to rather different forms of social behaviourin men and women.
Men, according to this argument, are pre-programmed for promiscuity: men’s selfish genes will maximize their (that is, their genes’) chances ofsurviving by the man having sex at every opportunity and with as manywomen as possible. Women, on the other hand, are, according to thistheory, pre-programmed for selectivity and settling down. Women’s selfishgenes will maximize their (that is, their genes’) chances of surviving bythe woman carefully selecting a mate who will produce the strongest, most-able-to-survive children, and who will stay around to protect andfeed her and the children until they reach sexual maturity. The differ-ence, it is proposed, comes about because, relatively speaking, womencan produce only a limited number of children in their child-bearing years,whereas men can inseminate large numbers of women and hence havemany children.
In sociobiology, direct links are often drawn between evolutionary adaptive strategies and highly enculturated social behaviour. As we sawat the beginning of the chapter, this includes housework. Gribbin andGribbin provide another typical example: In terms of evolutionary success, the prime requirements that a man should seek in a marriage partner are youth and health. . . . Awoman, on the other hand, requires rather different attributes in apartner. . . . She needed a male that had proved himself fit . . . Anda man proves himself fit firstly by surviving to a reasonable age, and secondly by achieving wealth or status within society. A womanwho mated with a successful older man was likely to leave moredescendants, in the long run, than a woman who chose a young,unproven male as her partner.
Baker (1996), in his book Sperm Wars, has taken this idea of genes directly and profoundly affecting behaviour even further. In it he claimsthat there is an evolutionary advantage to infidelity. He argues that a woman’s body, unconsciously primed by instinctive evolutionary forces,leads her into situations where she has sex with two men at the time when she is most fertile. Baker accords the body’s instinct an amaz-ing level of insight and cunning. Having described a situation where a woman has a one-night stand with an ex-boyfriend, he suggests the following: The underlying strategy her body was pursuing was that, no matterwho fathered the child, the man best suited to help her raise the child is her partner. It was vital to this strategy, therefore, that anyinfidelity should not be discovered. . . . When she gets home, she works very hard to have sex with her partner. Consciously, she will have seen this as helping to avoid detection. If she can get herpartner to inseminate her, any tell-tale damp patch on the sheets or any smell of semen will not arouse his suspicions. What her con-scious mind will not realise, though, is that having collected spermfrom her ex-boyfriend, her body is now very keen to collect spermfrom her partner. Her body has already decided that, on balance,her ex-boyfriend would make a better genetic father than her partner.
The one thing it does not know is how the ejaculates compare. She wants to have her egg fertilized by her ex-boyfriend only if his ejaculate is also the more fertile and competitive. The way forher to discover this is to pit one ejaculate against the other. In other words, her body wants to promote sperm warfare between the (Baker 1996: 43–4; emphasis in the original) Early sociobiological theorization (see, for example, Alexander 1974) speculated that the drives towards particular behaviours were directlyencoded in the genes. A rather more subtle kind of theorization has now been developed as evolutionary psychology (see, for example, Buss1990, 1996; Gribbin and Gribbin 1998; Wright 1996).
Evolutionary psychology
The key element to evolutionary psychology is the idea that natural selection operates on expressed behaviours. In this way it can impact on underlying psychological mechanisms, favouring those that promotesuccessful reproduction and militating against those associated withnon-reproduction. Of course, because we cannot inherit acquired char-acteristics, any such process must have a grounding at a genetic level. Thepsychological mechanisms and their expression (for example, altruism)need to have a level of predisposition in the genes.
Proponents of evolutionary psychology argue that their theory helps to make sense of empirical findings from experimental social psycho-logy. For example, some research suggests that people are more likely to help (be altruistic towards) strangers who look, act and think like themselves. Such strangers, they claim, are more likely to have a geneticresemblance. In other words, propinquitous altruism indirectly favoursthe genetic profile of the helper through supporting the person helped(Rushton 1989).
Men across a range of cultures have been shown to favour youthful-looking women (Cunningham 1986; Buss 1989). They also findwomen more attractive if their waists are about a third narrower thantheir hips (Singh 1993). If such preferences are the result of a partiallyinherited mechanism, as evolutionary psychologists would suggest, thenmen would seem to be ‘wired up’ to choose reproductive partners whose youthful fertility offers the best chance of genetic profiles beingreproduced.
It is worth noting that a problem with this kind of theorization is that a plausible story can be told to explain almost any ‘facts’. Were the result otherwise – for example, if men showed a preference for rathermore mature women who have already given birth – it could be arguedthat their choices were for experienced, ‘better’ mothers. The theory, moreover, is completely untestable.
Similar problems apply to research into women’s notions of male attractiveness. Buss (1994) has argued from an evolutionary psychologyperspective that this is mediated by selection for protection and support(that is, men who seem mature and dominant). However, more recentresearch (Perrett 1998) using image ‘morphing’ suggests that women pre-fer men’s faces that are not over-masculine (in the sense of strong jaws and heavy brows). However, he did also confirm a male preference for more‘feminine’ women’s faces. Again, Perrett’s finding about men’s faces canbe explained in evolutionary psychology language. ‘High testosterone’ facesjust might signal violent, unstable partners, and to avoid them might bringa man with better parenting potential. However, the evidence for such alink is far from clear, and the ability of evolutionary psychology to assimil-ate contradictory contentions (for example, between Buss and Perrett) is not encouraging.
Summary box
Sociobiology and evolutionary psychology
It is worth reiterating that sociobiology and evolutionary psychology fallat the first post when it comes to scientific method. Both are inherentlyuntestable. Their claims cannot be subjected to empirical test, and, cruci-ally, cannot be falsified. They operate only at the level of speculation.
Moreover, both sociobiology and evolutionary psychology are highly selective in the range of human behaviour on which they base their
speculations. They focus on the most banal of ‘normal’ sexual behaviour,
mainly that of the stereotypical heterosexual couple engaging in penetrat-
ive sex, albeit taking infidelity into their remit. The sheer diversity and
range of people’s sexual interests, behaviours and turn-ons raises serious
doubts about the ability of thee theories to explain human sexuality.
It is, for example, hard to see how sadomasochism can have any
possible evolutionary advantage. And yet this practice is much more
common than most people realize. Sadomasochism is less about pain
than it is about playing around with power, dominance and submission
– the sexual pleasure to be gained by acting in either (or, at different
times, both) submissive or dominant roles. As such it highlights the
subtle qualities of insight, desire and knowledge that make us human,
and separate us from lower animals. While both humans and animals
can be sexual, only humans can be erotic. Indeed, the very word ‘erotic’
conveys what is most human about human sexuality, stressing the
cultural features of human desire. Whether we are talking about sexy
underwear, leather gear or red roses, it is hard to see how these can
have anything other than symbolic meanings. Certainly their ability to
seduce and arouse cannot, surely, be programmed into the genes?
What is at stake, here, however, is not just a matter of poor science and limited theorization. As was mentioned at the beginning of this chapter, biological explanations of human sexuality and gender are cur-rently becoming popular, and are actively favoured by the media. It isinteresting to speculate why. One reason is that they are highly plausibleand offer neat and simple explanations. Another, more worrying, is thatthey feed into the anxieties and preoccupations of those with the powerto determine what is written and broadcast (and, indeed, researched).
Generally these are middle-aged and older men who have a stake inpromoting the idea that it is ‘natural’ for men to be sexually predatory,especially on younger women. Equally, such men have a stake in fos-tering the perception that women are nagging harpies who constantlycomplain about men’s untidiness and disinterest in housework.
In other words, we should not just look at theories in terms of their scholarly adequacy. We need also to consider their impact upon how people live their lives. Sociobiological and evolutionary psychology theories have largely been formulated in highly misogynist terms, in that they serve male interests and prejudices. Accepted uncritically they encourage us to view certain aspects of human sexual behaviour as‘natural’ and thus, by implication, as irresistible. They draw attentionaway from the ethics of how people should behave. As you will see inChapter 10, this is now happening in relation to rape, with claims beingmade that it is a product of evolutionary force. We would argue thatsuch a claim insults men as much as it can contribute to creating con-ditions that, at the least, devalue women and, at the worst, may increasetheir vulnerability to sexual assault.
Significant differences
Adopting a biopsychological approach need not, and should not, be takenas saying the same thing as ‘biology is destiny’. Indeed, neo-Darwinianevolutionary theory requires an environment through which change is medi- ated and genetic potential is manifested. Increasingly, that environmentis human-made rather than ‘natural’. Only over quite long periods of time do such changes (sometimes) become a permanent feature of thespecies, as was the case for the variations Darwin noted on the dif-ferent Galapagos Islands. Human evolution, in the sense of stable, non-reversible developments, takes place over long time-scales. The pop-ulation of present-day Rome is not more evolved in any significant biological sense than the population who lived in the city in the days ofthe Roman Empire – any differences are the result of cultural change.
However, it is equally true that biological differences (for instance,whether a particular inhabitant of Rome is female or male) led to majordifferences in life possibilities 2000 years ago, and that remains the case(if not so dramatically) today.
From the beginnings of modernism, both human biology and the human environment were seen as sites of intervention whereby thehuman condition could be improved, and this dual focus still operatestoday. However, it easily slips into a tension or an ideological choice, withthe disfavoured site being reduced to a trivial or subsidiary possibility – conservatives favouring biology as the site of action, progressivesfavouring the environment. Both possibilities can marshal research evid-ence and common sense into a compelling, and singularizing, story. Thecase for environmental centrality follows in the next chapter.
Further reading
Burr, V. (1998) Gender and Social Psychology. London: Routledge.
Trew, K. and Kremer, J. (1998) Gender and Psychology. London: Arnold.

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