Perspectives in Behavior Genetics

John L. Fuller, Edward C. Simmel, John L. Fuller, Edward C. Simmel

• Publisher: Routledge
• Year: 2021
• eBook ISBN: 9781000388633
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Originally published in 1986, we were living in a world in which the number of publications in behaviour genetics had reached a point where it was difficult, even for those teaching the subject, to keep up with the literature. The editors of this title believe that there is a need for people who have planned and executed long-term research programs to summarize and comment on their results. This volume was intended to help meet that need. The authors were given free choice of subject and format. The result is a variety of topics that had been researched mainly over the previous decade. Chapter 1 is an exception and looked back at the work of others in behaviour genetics over a quarter-century and tried to detect trends in the types of research done in the field.

1

Trends in Behavior Genetics: 1960–1985

John L. Fuller
State University of New York at Binghamton

Edward C. Simmel
Miami University, Oxford, OH

DOI: 10.4324/9781003156239-1

INTRODUCTION: A VIEW FROM 1957

Our contribution to this volume is a study of trends in the genetics of behavior over the past 25 years, 1961–1985. Before doing so, we are presenting brief excerpts from three papers delivered at the 1956 conference of the Milbank Memorial Fund entitled “The Nature and Transmission of the Genetic and Cultural Characteristics of Human Populations.” Each of the authors eventually served a term as president of the Behavior Genetics Association (BGA). All three directed their remarks to general issues that are still relevant to this area of science.

Dobzhansky (1957) entitled his presentation “The Biological Concept of Heredity as Applied to Man.” He noted at the start that “the traditional dichotomy of hereditary versus environmental traits is invalid” (p. 11). He emphasized the importance of genes by noting that “one has to be human to learn any human language, hence the learning process presupposes a human genotype” (p. 11). “Your genes … have determined your intelligence, but only in the sense that a person with a different genotype might have developed differently if his life experiences were approximately like yours (p. 13). We inherit genes—not characters or traits…. Genes determine processes, not states” (p. 14).

Continuing, he stated, “It is … legitimate to inquire what part of the observed variance in a given trait is due to the diversity of human genotypes, and what to the environments in which men develop…. No single or simple answer to this question (the relative weights of genotypes and environmental variables in the causation of observed human differences) is possible because the weights are different for different traits…. The demonstration that a given trait is conditioned by heredity does not … exclude the possibility that variation is controlled also by environmental influences” (p. 15). And finally: “The observed degree of heritability of a given character difference may be valid only for that time, place, and material studied” (p. 16). These precepts have become a guide for researchers in behavior genetics, and we believe that for the most part they are widely observed. Dobzhansky and other pioneers set a code of procedures that made behavior genetics the study of nature and nurture rather than of nature or nurture.

Thompson (1957) was particularly interested in personality and intelligence differences in populations. He noted that “Human groups must be demonstrated not only by physical, but also by psychological variables” (p. 38). “So long as there is assortative mating with respect to … these characters, we can expect to find genetically determined group differences” (p. 39). Thompson was not referring to “ethnic differences,” but to groups of any kind that differ in modal behavior. On genic versus environmental explanations of behavioral differences, he stated that “within the limits of scientific facts we can feel free to proceed in either direction without embarrassment” (p. 40). The conciliation he predicted is not universal, but we believe that the majority of biologists and psychologists accept an interactive gene-environment model of behavioral development. Universal agreement on particular cases has not and may never be achieved. Thompson’s view was that “The problem of separating genetic from environmental determination is difficult, but it is not insoluble” (p. 49). He considered culture-free tests to be an unsatisfactory approach, and favored multiple variance analysis. As a final way of disposing of the nature-nurture problem he suggested measuring phenotypic transmission of psychological characters without attempting to measure the relative importance of heredity and environment. We suspect this was written with tongue in cheek, but it is a convenient way to challenge die-hard environmentalists.

A third presentation at the Milbank conference dealt with pathways between genes and behavioral characteristics excluding defects in physical development or metabolism involving chromosomes that produce gross defects in physical or mental characteristics (Fuller, 1957). Behavior genetics asks questions regarding correlations between behavioral phenotypes and genotypes. Evidence for such correlations in animals comes from various sources: (1) behavioral effects of single-locus differences such as the reduction of male mating drive in Drosophila by the yellow gene; (2) successful selection for behavioral characters in insects and mammals; (3) examples of behavioral variation among inbred strains, and reduced variation within such strains.

With respect to the analysis of human behavior Fuller wrote, “Human populations are not good material for evaluating the effects of single genes on behavior unless the gene produces abnormal development” (p. 103). He suggested that, because we cannot carry out selection experiments on our own species, we should investigate the effects of assortative mating. On the question of ethnic differences in behavior he noted that differences exist in characteristics such as blood groups, pigmentation, hair distribution, and other somatic characters. Why should there not be a genetic contribution to ethnic differences in behavioral characteristics? He believed, however, that they would be of minor significance.

Fuller also advocated a physiological approach to psychogenetics, ranging from studies on cellular enzymes and hormones to the structure and functions of the somatic and autonomic nervous systems. Progress in this area should go beyond analysis of single-gene effects on mental deficiency. For example, it would be interesting to study the role of genes on variation of social behavior within a species. As an example he cited studies of social interactions among breeds of dogs (Scott & Fuller, 1965). He also proposed that humans were not selected for uniformity of behavior, but for diversity within an organized society. The contrary hypothesis that any healthy individual could fill any niche in society seemed to have little empirical support.

Clearly, by the late 1950s the framework of a new discipline was taking form. Although it was not based on eugenics, it would deal with a wide range of human problems that had interested the eugenicists. The difference was that it emphasized that both environments and genes should be considered when scientists tried to better the human condition through biology and social science. What we now call behavior genetics (alternatively behavioral genetics) has its roots in comparative and differential psychology, the behavioral element within zoology, and a variety of medical specialities that dealt with psychopathology and mental deficiency. Behavior genetics today is a synthesis of elements from these disciplines. Its openness to contributions from a variety of sources is a source of strength. It could not have survived without cooperation among scientists with different skills and common objectives.

NOTES ON BEHAVIOR GENETICS IN 1960

Recognition of Behavior Genetics as a designated discipline might be said to begin with Fuller and Thompson’s Behavior Genetics published in 1960. The book did not propose a new orientation combining biology and psychology. It was an effort to summarize the research of many scientists, mainly from the United States and Europe. Its predecessors were scattered articles in various biological and psychological journals. Actually, the beginnings of behavior genetics precede written records. The humans who domesticated horses, cattle, dogs, and ducks altered their behavior by genetic selection using procedures similar to those of today’s scientists who breed mice and fruit flies in their laboratories.

In the 1940s and 1950s considerable behavior genetic research with both animals and human subjects was carried on by psychologists and biologists. Hall (1951) reviewed experimental animal studies (mostly with mice and rats) of selective breeding for maze learning, aggression, audiogenic seizures, and other behaviors that could be quantitatively measured. He outlined the basic genetics required for research on laboratory animals, and described the characteristics of inbred strains. McCleam (1963) traced the history of ideas regarding the heritability of behavior from about 8,000 B.C. to 1960. Drosophila, mice, rats, and humans were the species most studied, and they are still predominant. For human data, family correlations, twin studies, and adoption studies were the most used techniques. (They are now, but the statistical designs of present-day researchers are more sophisticated.) Animal research dealt with inbred and selected lines, and single-gene effects.

Scientists as a group are curious regarding relationships between phenomena, and behavioral geneticists are no exception. Regardless of immediate economic application, they study genetic and environmental factors (physical and social) that affect behavior. They seem to have divided their attention between topics that are relevant to human welfare (for example, psychopathology) and topics related to general issues dealing with intraspecific variation in individual and group behavior in mice and insects. It is an error to conclude that behavior geneticists neglect environmental contributions to behavioral development. Major areas of their research include (1) the effects of selection on behavior, (2) the interaction of genotypes with environmental factors, (3) the biochemical and anatomical factors associated with specific behavioral phenotypes, (4) identification of the genes involved with specific behavioral syndromes, and (5) the role of genes in the ontogeny of behavior. Some behavior geneticists concentrate on problems related to human behavioral disorders or deficiencies, mainly working directly with human subjects but sometimes with animal models. Others are concerned with understanding the nature of gene-environment interactions on behavior without considering their direct application to human or animal welfare. We come from a variety of backgrounds and have different skills and interests.

BEHAVIOR GENETICS IN ACADEMIA

Our major emphasis in this chapter is the “producers” of behavior genetics and their “products”: research and the dissemination of knowledge through conferences, books, chapters, and journals. Equally important, however, are the “consumers” of the data obtained by the scientists and their reaction to the general principles espoused by the producers. Later in this chapter we consider some of the conflicts among scientists from a number of disciplines—essentially a continuation of the rather hoary nature-or-nurture argument. The fact is, however, that behavior genetics has consumers in many disciplines, among them medicine, physiology, education, evolutionary biology, and gerontology. However, the discipline with the closest and most direct ties to behavior genetics is almost certainly psychology. We believe that the relationship between genes and behavior should be part of a general education.

Two recent chapters by Fuller have dealt with the problems of a hybrid science. In “Psychology and Genetics: A Happy Marriage?” (1982) he predicted that disagreements between the disciplines will continue, but the results will be beneficial to both if reason wins over ideology. In “Psychology and Genetics” (1984) he considered relationships among psychology, genetics, and sociobiology. In this section we emphasize the influence of psychology on behavior genetics. It seems to us that further progress of the discipline depends as much (perhaps more) on new behavioral inputs as on progress in genetics. The cutting edge of genetics is at the molecular level, rather than at the level of genetics most directly related to behavior.

Psychology’s contribution to behavior genetics includes research methodology, measuring instruments, and other technologies used by researchers. It has also provided a “home” for instruction. Most behavior genetics courses are taught within departments of psychology. Most important, psychology has contributed people—the majority of individuals who consider themselves to be behavior geneticists have received their training in psychology. However, many individuals with medical or zoological backgrounds have made substantial contributions to the field. Workers in a hybrid research area must educate themselves in areas outside their formal education.

What impact has behavior genetics had on psychology? It may be too early, considering the youth of behavior genetics, to attempt an overall assessment of its impact on a major discipline such as psychology. We will, however, attempt to give a rough idea of its influence on psychological thinking. One index of an organized system of beliefs, methods, and findings is its incorporation into the introductory textbooks of a discipline. We can gain a general idea of the acceptance of behavior genetics in psychology through examining contemporary textbooks.

If a person who is totally naive with respect to the subject matter of modern psychology were to select certain recent books, such as Darley, Glucksberg, Kamin, and Kinchla (1984) at the introductory level, or Sarbin and Mancuso (1980) at the graduate-professional level, this person might be led to conclude that genetic approaches to normal and abnormal behavior are viewed by psychologists as highly controversial if not downright wrong. Other books by psychologists and biologists (e.g. Lewontin, Rose, & Kamin, 1984) deprecate the significance of genes for any variation in persona...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Title Page
• Original Copyright Page
• Contents
• List of Contributors
• Preface
• 1 Trends in Behavior Genetics: 1960–1985
• 2 Colorado Family Reading Study: An Overview
• 3 Audiogenic Seizures in Relation to Genetically and Experimentally Produced Cochlear Pathology
• 4 Toward the Genetics of an Engram: The Role of Heredity in Visual Preferences and Perceptual Imprinting
• 5 An Examination of Claims for Classical Conditioning as a Phenotype in the Genetic Analysis of Diptera
• 6 Genetic Factors and Human Reactions to Alcohol
• Author Index
• Subject Index