The International Behavioral Development Symposium was held in May in Minot, North Dakota to help promote scientific understanding of the contribution of biological factors to sexual orientation and sex differences in behavior. The symposium brought together many of the leading researchers in this area of study throughout the world.

PLENARY

Roger A. Gorski, UCLA School of Medicine, Los Angeles, California
Thoughts on the Sexual Differentiation of the Brain and The Origins of Sexuality: Fair or Foul?

SEX DIFFERENCES IN NEUROLOGY

Robert H. Lustig, University of Tennessee-Memphis
Sex Hormonal Modulation of Neural Organization In Vitro

Nick F. Swaab, et al., Netherlands Institute for Brain Research, The Netherlands
Sexual Differentiation of the Human Hypothalamus

Pauline Yahr, University of California, Irvine
Cell Groups and Pathways in the Brain that are Sexually Dimorphic, Hormone Sensitive and Involved in the Display of Male Sexual Behavior

C. Davison Ankney & J. Philippe Rushton, University of Western Ontario, Canada
Sex Differences in Brain Size and Cognitive Abilities

Susan M Resnick, NIA/Gerontology Research Center, Baltimore, Maryland
Gender Difference in Brain Structure and Function in the Elderly

DELINEATING SEX DIFFERENCES IN BEHAVIOR

Sergio M. Pellis & Evelyn F. Field, University of Lethbridge, Alberta, Canada
Difference or Differences in the Play Fighting of Male and Female Rats? The Sex of Play Revisited

Alan Dixson & Gillian Brown, University of Cambridge at Madingley, England
Sex Differences in Primate Behavior: Does Testicular Activity in Infancy Affect Behavioral Development

Christina L. Williams, Duke University, Durham, North Carolina
Sex Differences in Spatial Abilities

Alfonso Troisi, University of Rome, Italy
Effects of Gender and Interview Content on Non-verbal Behavior of Normal Subjects

Kay B. Hoyenga & Kermit T. Hoyenga, Western Illinois
University, Macomb
The Interpersonal Circle: Usefulness in Understanding Sex Differences in Personality, Sociopathy, and Depression

SEXUAL DIFFERENTIATION VIA DRUGS AND STRESS

Gyorgy Csaba, Semmelweis University of Medicine, Hungary
Effects of Perinatal and/or Pubertal Steroid Treatments on the Sexual Hormone Levels, Receptors, and Behaviour of Adult Rats

Ingeborg Ward & O. Byron Ward, Villanova University, Pennsylvania
Environmental and Pharmacological Factors that Alter Sexual Differentiation of Males During Fetal Life

Ilona Vathy, Albert Einstein College of Medicine, Bronx, New York
Gender Specific Alterations in Adult Sexual Behavior and Brain Neurotransmitters Following Prenatal Morphine Exposure

Craig Kinsley, University of Richmond, Virginia
Prenatal Stress-Induced Variability in the Expression of Sex-Typical Physiology and Behavior

Margaret Forgie & Jane Stewart, University of Lethbridge, Alberta Canada
Sex Steroids Modulate the Behavioral Effects of Stimulant Drugs

THE NATURE OF SEXUAL ATTRACTION

Victor Johnston, New Mexico State University, Las Cruses
The Biological Basis of Facial Beauty

Devendra Singh, University of Texas, Austin
Human Body Shape and Mate Choice

Linda Mealey & Andy Heim, St. John's University, Collegeville, Minnesota
Bulking Up: The Role of Gender and Sexual Orientation on Attempts to Manipulate Physical Attraction

Delbert Thiessen, University, of Texas, Austin
The Invisible Threads of Assortative Mating

NEUROCHEMISTRY AND SEXUAL ORIENTATION

A. Koos Slob & Julie Bakker, Erasmus University, The Netherlands
On the Origin of Sexual Partner Preference in the Male Laboratory Rat: Behavioral, Anatomical, and Immunocytochemical Studies

Elaine M. Hull, et al., State University of New York, Buffalo
Brain Dopamine in the Organization and Activation of Male Sexual Behavior

Hartmut A. G. Bosiniski, et al., Christian Albrechts University, Germany
Brain-MRI and Endocrinology Findings in Heterosexual Females, Males and Female-to-Male Transsexuals

Nathaniel McConaghy, Prince of Wales Hospital, Randwick, Australia
Should Biological Theories of Sexual Orientation Ignore Feelings?

DEVELOPMENTAL PROCESSES IN SEXUAL ORIENTATION

Yasumasa Arai, et al., Juntendo University School of Medicine, Japan
Lordosis Behavior in Male Rats: The Presence of Inhibitory Mechanisms of the Display of Lordosis

Michael J. Baum & R. G. Paredes, Boston University, Massachusetts
Altered Sexual Partner Preference in Male Ferrets Given Excitotoxic Lesions of the Preoptic Area/Anterior Hypothalamus

Francesca R. D'Amato, Institute of Psychobiology and Psychopharmacology, Italy
Individual Recognition in Mice: Relevance of Genetic Versus Familiar Cues in Males and Females

Ritch C. Savin-Williams & Kenneth M. Cohen, Cornell University, Ithaca, New York
Developmental Pathways of Sexual Identity Formation Among Gender Non-Conforming and Gender Conforming Gay and Bisexual Male Youths

Milton Diamond, University of Hawaii, Honolulu
A Critical Look at the Evidence for the Environmental Basis for Sexual Orientation and Sexual Identity

GENETIC INFLUENCES ON SEXUAL DIFFERENTIATION

David E. Comings, City of Hope National Medical Center, Duarte, California
The Molecular Genetics of Human Sexual Behavior

William J. Turner, Albuquerque, New Mexico
Asexuality, Homosexuality, and Transsexuality

Dean Hamer, National Institutes of Health, Bethesda, Maryland
The Role of Genes in Sexual Orientation and Sex-Typical Behavior

Scott Hershberger, University of Minnesota, Minneapolis
Sexual Orientation in Males and Females: Same Genes, Different Effects

J. Michael Bailey, North Western University, Evanston, Illinois
A Population-Based Twin Study of Sexual Orientation

Ray Blanchard, Clarke Institute, Toronto, Ontario, Canada
In Search of Biological Explanations for the Later Than Expected Birth Order of Homosexual Males

SEX DIFFERENCES IN SIDEDNESS AND PRE-CONCEPTUAL PROGRAMMING OF SEXUAL ORIENTATION

Uner Tan, Ataturk University, Turkey
Asymmetric Motor Control in Male and Female Cats and Humans

Anna Herman-Jeglinska, Nencki Institute of Experimental Biology, Warszawa, Poland
Hand Preference in Female-to-Male and Male-to Female Transsexuals: Effects of Biological Sex and Familial Sinistrality

Irina Pollard, Macquarie University, New South Wales, Australia
Pre-Conceptual Programming and the Evolution of a Continuum of Normal Sexual Orientations

SEXUAL ORIENTATION, SEX-TYPICAL BEHAVIOR, AND EVOLUTION

Lynwood G. Clemens, Dry M. Lange & Lian-Yo Yang, Michigan State University, East Lansing
Differentiation of the Copulatory Pacemaker in Rats

Anne Perkins & James A. Fitzgerald, Carrol College, Helena, Montana
Physiological Correlates to Homosexual Orientation in Domestic Rams

Ralf W. Dittmann, Lilly Deutschland GmbH, Bad Homburg, Germany
Sexual Behavior and Sexual Orientation in Females with Congenital Adrenal Hyperplasia

Brian A. Gladue, University of Cincinnati, Ohio
Sexual Orientation and Aggression

Guenter Dorner, & Rolf Lindner, et al., Humbolt University Medical Center (Charite), Berlin, Germany
Gene and Environmental Dependent Brain Organization, Sexual Orientation, and Sex-Typical Behavior

SEX DIFFERENCS IN NEUROCHEMISTRY AND HORMONE LEVELS

Matthew Grober, University of Idaho, Moscow, Idaho
Sexual Plasticity in Fish: Evidence for Conserved Social and Neuroendocrine Mechanisms Driving Variation in Vertebrate Sexual Orientation

Catherine Wilson & Isabel Gonzalez, St. George's Hospital & Medical school, London, England
The Involvement of 5HT receptor Mediated Effects on Neonatal Sexual Differentiation of Behaviour as Seen in Adulthood

Doreen Kimura & Jeff Hall, University of Western Ontario, London, Ontario, Canada
Sex, Sexual Orientation, Sex Hormones and Body Asymmetry Influence Human Cognitive Function

Edward Miller, University of New Orleans, Louisiana
Evidence for Behavioral Effects of Prenatal Sex Hormone Transfer from the Study of Opposite-sex Twins

Kerrin Christiansen, University of Hamburg, Germany
The Role of Sex Hormones in Human Aggression

SEX DIFFERENCES IN COGNITION

Helmuth Nyborg, University of Aarhus, Denmark
Androtyping Male Sexual Development

Diane Halpern, California State University, San Bernadino
The Sex of Cognition

Santha Kumari, Thepar Institute of Engineering and Technology, Punjab, India
Selection Organismic Variables Influencing Spatial Task Performance: Some Recent Findings

James D. Weinrich, University of California, San Diego
Childhood and Adult Predictors of Genitoerotic Role Among Homosexual and Bisexual Men

PERINATAL HORMONES AND SEXUAL ORIENTATION

Kathleen C. Chambers, University of Southern California, Los Angeles, California
Hormonal and Neural Basis of the Sexual Dimorphism in Conditional Food Aversions

Heino F. L. Meyer-Bahlburg, Columbia University, New York
The Role of Prenatal Estrogens in Sexual Orientation

Kenneth J. Zucker, Clarke Institute of Psychiatry, Toronto, Ontario, Canada
Sibling Sex Ratio: Relation to Gender Identity and Sexual Orientation in Males

POSTER PRESENTATIONS

Anthony Bogaert, Clarke Institute, Toronto, Ontario, Canada
Handedness in Homosexual and Heterosexual Men: An Analysis of the Kinsey Data

Lee Ellis, Minot State University, North Dakota
Sibling Sex Ratios and Birth Orders Among Male and Female Homosexuals

Elizabeth Hampson, J. F. Rovet, & D. Altmann, University of Western Ontario, London, Canada
Sports Participation and Physical Aggressiveness in Children and Young Adults with Congenital Adrenal Hyperplasia

David W. Holtzen, Waban, Massachusetts
Sexual Orientation and Handedness: A Re-analysis of Recent Data and Research Considerations for Future Inquiry

James V. Kohl, Partell Medical Center, Las Vegas, Nevada
Human Pheromones: Linking the Nature and the Nurture of Human Sexuality Through Reciprocity in Olfactory-Genetic-Neural-Hormonal-Behavioral Relationship

Santha Kumari & George Kurian, Thapar Institute of Engineering, Punjab, India
Sexuality and Reproduction: A Psychobiological Thesis

Gary M. Lange, Lynwood G. Clemens, Michigan State University, East Lansing
Developmental Factors Influencing the Temporal Aspects of Female Copulatory Behavior in Rats

Richard Lippa, California State University, Fullerton
Gender-Related Individual Differences and National Merit Test Performance: A New Analysis of Loehlin and Nichol's (1976) Twin Data

J. Vega Matuszczyk, R. S. Appa, & K. Larsson, University of Gotenborg, Sweden
Role of Perinatal Estrogen on Ontogenesis of Sexual Orientation and Behavior of Male Rats

Geoffrey Sanders & Deborah Wenmoth, London Guildhall University, London, England
Oestrogen Levels and the Performance of Sexually Dimorphic Tasks

Nancy Segal, California State University, Fullerton
Gender Differences in Bereavement Responses and Longevity: Findings from an On-Going Study of Twins

Liang-Yo Yang & Lynwood G. Clemens, Michigan State University, East Lansing
Stimulus Factors Influencing the Temporal Aspects of Female Copulatory Behavior in Rats