Stephen J. Suomi, Ph.D.
M.I.N.D. Institute Distinguished Lecturer Series: December 13, 2006
Stephen J. Suomi, Ph.D., is chief of the Laboratory of Comparative Ethology at the National Institute of Child Health & Human Development (NICHD), National Institutes of Health in Bethesda, Maryland. He also holds appointments as Research Professor at the University of Virginia (Psychology), the University of Maryland, College Park (Human Development), and The Johns Hopkins University (Mental Hygiene), and is an Adjunct Professor at Georgetown University (Psychology), the Pennsylvania State University (Human Development) and the University of Maryland, Baltimore County (Psychology).
Dr. Suomi has received international recognition for his extensive research on biobehavioral development in rhesus monkeys and other primate species. His initial postdoctoral research successfully reversed the adverse effects of early social isolation, previously thought to be permanent, in rhesus monkeys. His subsequent research at Wisconsin led to his election as a Fellow of the American Association for the Advancement of Science ‘for major contributions to the understanding of social factors that influence the psychological development of nonhuman primates.” Since joining the NICHD he has identified heritable and experiential factors that influence individual biobehavioral development, characterized both behavioral and physiological features of distinctive rhesus monkey phenotypes, and demonstrated the adaptive significance of these different phenotypes in naturalistic settings. His present research focuses on three general issues: the interaction between genetic and environmental factors in shaping indivdual developmental trajectories, the issue of continuity vs. change and the relative stability of individual differences throughout development, and the degree to which findings from monkeys studied in captivity generalize not only to monkeys living in the wild but also to humans living in different cultures.
Aggression, Serotonin and Gene-Environment Interactions in Rhesus Monkeys and Primates (4 pm)
Recent research with both humans and rhesus monkeys has provided compelling evidence of gene-environment interactions (G x E) throughout development. For example, a specific polymorphism (“short” allele) in the promoter region of the serotonin transporter (5-HTT) gene is associated with deficits in neurobehavioral functioning during infancy and in poor control of aggression and low serotonin metabolism throughout juvenile and adolescent development in monkeys who experienced insecure early social attachments but not in monkeys who developed secure attachment relationships with their mothers during infancy. In contrast, monkeys possessing the “long” allele of the 5-HTT gene exhibit normal neurobehavioral functioning, control of aggression, and serotonin metabolism regardless of the relative security of their early attachment relationships. One interpretation of these G x E interaction data is that the long 5-HTT allele somehow confers resiliency to adverse early attachment relationships on those individuals who carry it (“good genes”). An alternative interpretation of the same data is that secure attachment relationships somehow confer resiliency to individuals who carry alleles that may otherwise increase their risk for adverse developmental outcomes (“maternal buffering”). These two interpretations are not mutually exclusive, but the differences in their respective implications for developing effective strategies for successful intervention in and even prevention of adverse developmental outcomes in affected individuals are considerable. Moreover, genetic analyses of several other macaque species, as well as all of the great ape species, have revealed that although all of these species possess the 5-HTT gene, they do not have any of the functional polymorphisms found in humans and rhesus monkeys, i.e., in each case there is no within-species functional allelic variability for this gene. Implications of these recent findings will be discussed.
Up-tight, Laid-back, and Jumpy Monkeys (6 pm)
Recent research has found marked individual differences in patterns of rhesus monkey biobehavioral development throughout the life span. Approximately 20% of monkeys growing up in naturalistic settings consistently display unusually fearful and anxious-like behavioral reactions to novel, mildly stressful social situations throughout development; another 5-10% are likely to exhibit impulsive and/or inappropriately aggressive responses under similar circumstances. These distinctive behavioral patterns and their biological correlates appear early in life and remain remarkably stable from infancy to adulthood. Both genetic and experiential mechanisms are implicated not only in the expression of these patterns but also in their transmission across successive generations of monkeys. For example, a specific polymorphism in the serotonin transporter gene is associated with deficits in infant neurobehavioral functioning and in juvenile and adolescent control of aggression and serotonin metabolism in monkeys who experienced insecure early attachments but not in monkeys who developed secure attachment relationships with their mothers during infancy (“maternal buffering”). Moreover, because the attachment style of a monkey mother is typically “copied” by her daughters when they grow up and become mothers themselves, similar buffering is likely to occur for the next generation of infants carrying that specific polymorphism.