Evolution of Vulnerability: Implications for Sex Differences in Health and Development

Biologists have known for decades that many traits involved in competition for mates or other resources and that influence mate choice are exaggerated, and their expression is influenced by the individuals’ ability to tolerate a variety of environmental and social stressors. Evolution of Vulnerability applies this concept of heightened sensitivity to humans for a host of physical, social, psychological, cognitive, and brain traits. By reframing the issue entirely, renowned evolutionary psychologist David C. Geary demonstrates this principle can be used to identify children, adolescents, or populations at risk for poor long-term outcomes and identify specific traits in each sex and at different points in development that are most easily disrupted by exposure to stressors.

Evolution of Vulnerability begins by reviewing the expansive literature on traits predicted to show sex-specific sensitivity to environmental and social stressors, and details the implications for better assessing and understanding the consequences of exposure to these stressors. Next, the book reviews sexual selection―mate competition and choice―and the mechanisms involved in the evolution of condition dependent traits and the stressors that can undermine their development and expression, such as poor early nutrition and health, parasites, social stress, and exposure to man-made toxins. Then it reviews condition dependent traits (physical, behavioral, cognitive, and brain) in birds, fish, insects, and mammals to demonstrate the ubiquity of these traits in nature. The focus then turns to humans and covers sex-specific vulnerabilities in children and adults for physical traits, social behavior, psychological wellbeing, and brain and cognitive traits. The sensitivity of these traits is related to exposure to parasites, poor nutrition, social maltreatment, environmental toxins, chemotherapy, and Alzheimer’s disease, among others. The book concludes with an implications chapter that outlines how to better assess vulnerabilities in children and adults and how to more fully understand how, why, and when in development some types of environmental and social stressors are particularly harmful to humans.

• Describes evolved sex differences, providing predictions on the traits that will show sex-specific vulnerabilities
• Presents an extensive review of condition-dependent traits in non-human species, greatly expanding existing reviews published in scientific journals, and more critically, extending these to humans
• Applies condition-dependent traits to humans to identify children, adolescents, or populations at risk for poor long-term outcomes

David C. Geary is a cognitive developmental and evolutionary psychologist at the University of Missouri. He has wide ranging interests but his primary areas of research and scholarly work are children’s mathematical cognition and learning and Darwin’s sexual selection as largely but not solely related to human sex differences.

Professor Geary directed a 10-year longitudinal study of children’s mathematical development from kindergarten to ninth grade, with a focus on identifying the core deficits underlying learning disabilities and persistent low achievement in mathematics. The study was funded by the National Institutes of Health (US), including through a MERIT award to professor Geary. One result has been the identification of the school-entry number knowledge that predicts economically-relevant mathematical competencies in adolescence. As a follow-up, professor Geary is directing a second longitudinal study, funded by the National Science Foundation (US), to identify the preschool quantitative competencies that predict this school-entry number knowledge. Professor Geary has also published conceptual and theoretical articles on individual differences in children’s mathematical learning, as well as a book published by the American Psychological Association, Children’s mathematical development (1994); recently translated into Korean. Professor Geary has also contributed to applied and policy related work on this topic, serving, for instance, on the President’s National Mathematics Advisory Panel, and chairing it’s learning processes task group.

Professor Geary’s interests in evolution are reflected in two of his other books published by the American Psychological Association, The origin of mind: Evolution of brain, cognition, and general intelligence (2005), and Male, female: The evolution of human sex differences (1998, 2010 second edition). The corresponding empirical work ranges from the study of changes in brain volume during hominid evolution to human mate choices to hormonal responses to simulated (video game) competition. Professor Geary’s current interests in this area follow from several of his collaborative studies on the effects of prenatal toxin exposure on sex differences in cognition and behavior in mice. Specifically, traits related to Darwin’s sexual selection are often exaggerated relative to other traits. These would include, for example, the bright plumage of the males of many species of bird that in turn is a good indicator of their behavioral and genetic health. These traits are particularly sensitive to environmental disruption, even in healthy individuals. Professor Geary’s in progress book, The evolution of vulnerability, is focused on these traits in humans and how they can be used to identify at-risk populations and individuals.