The Genetic Inferno: Inside the Seven Deadly Sins

Exploring a realm similar in complexity to Dante's Purgatorio, Medina (The Clock of Ages) skillfully uses the seven deadly sins to guide the lay reader through an ambitious discussion of the relation between genes and behavior. Although it is impossible to offer any definitive answers concerning the extent to which a personality is genetically predetermined, this illuminating survey examines the nature of consciousness as well as the biological basis of emotions. For instance, Medina explains how neurons can be primed by experience to release ""fear response"" signals, so that a childhood of poverty can dispose a person toward greediness, even in the absence of a financial threat. Similarly, an extended period of starvation may disrupt the body's regulatory system and cause gluttony, in which one overindulges despite an abundance of food. As Medina admits, however, we are far from identifying all the components involved in the process of learning these behaviors. Despite the long strides researchers have made studying circadian rhythms (""sloth"") and the genetic basis of aggression (""wrath"") in animals, extrapolating these findings to humans is controversial, and the reader may feel more overwhelmed by what we don't yet know than satisfied by the kernels of knowledge that we do possess. More a speculative introduction than a definitive investigation into the genetics of emotion, this survey is best suited for biopsychology buffs and, in the author's words, ""literature majors, political science types, business people"" with a scientific bent rather than research professionals. (Nov.)