David M. Buss
Charles Darwin coined the apt phrase “the hostile forces of nature” to describe the elements that impede an organism's survival. He described three fundamental classes of hostile forces. The first involves struggles with the physical environment, such as extremes of climate and weather, falling from dangerous heights, or being swept away by landslides or tsunamis. The second involves struggles with other species, such as predators, parasites, and prey. The third involves struggles with conspecifics. To some extent, this tripartite scheme oversimplifies, since adaptive problems obviously cut across classes. Finding prey for food, for example, requires navigating the physical environment, dealing with the evolved psychology of prey animals, and sometimes out-competing conspecifics. Nonetheless, Darwin's “hostile forces of nature” provide a natural starting point for the adaptive problems of survival that humans recurrently confronted.
Chapter 6 provides an entirely new chapter on the evolutionary psychology of food and food choice, by Paul Rozin and Peter Todd. Although many modern humans take food abundance for granted, human ancestors spent considerable time obtaining and processing the food on which their survival depended. Rozin and Todd explore what we know about how humans find and exploit possible food sources; how people decide what to eat; describe adaptations for neophobia and neophilia; explore the consequences of evolved preferences for sweet and fatty foods; explore cultural adaptations for processing foods such as corn and manioc; describe the fascinating origins of milk and other forms of dairy consumption, a classic case of gene-culture co-evolution; articulate the importance of meat as a source of vital nutrients but also a vector of microbes; and end with the future of food and how evolved adaptations play out in modern cultural contexts.
Mark Schaller provides an entirely new chapter on the behavioral immune system (Chapter 7). Most are familiar with our physiological immune system, but fewer are aware of the growing evidence for an analogous behavioral immune system, a key element of which is the emotion of disgust. The behavioral immune system, Schaller argues, helps humans to prevent infection to begin with—a proactive defense rather than a reactive defense after pathogens have intruded. It has unique implications not just for avoiding dangerous foods, but also for social phenomena, since other humans are disease vectors. Hence, the behavioral immune system has profound implications for interpersonal attraction and repulsion, stigma and prejudice, conformity, and even culture. This chapter highlights the dramatic explosion of evolutionary psychological research in a domain that was almost entirely absent a decade ago.
Chapter 8, by Irvin Silverman and Jean Choi, describes theory and research on human spatial navigation and landscape preferences. These features of human evolutionary psychology are critical for a host of adaptive problems. Adaptive challenges include finding shelter that offers protection from hazardous elements, locating water sources, and finding food that can be gathered or hunted. Silverman and Choi describe important discoveries about spatial abilities, such as female superiority in spatial location memory, that were entirely missed by previous generations of psychologists who lacked the lens of evolutionary psychology.
Chapter 9, by Clark Barrett, provides a groundbreaking theoretical analysis and relevant empirical studies on human interactions with two classes of species—predators and prey. He furnishes evidence for specialized psychological adaptations attuned to unique design features of predators and prey, such as self-propelled motion, morphology, contingency, and directed gaze. Although this line of research is relatively new, Barrett elucidates the exciting discoveries already made and the promise of many more to come.
Joshua Duntley devotes Chapter 10 to other humans as one of the most important “hostile forces of nature.” He describes recurrent arenas of human conflict, and argues that humans have adaptations both to inflict costs on other humans and to defend against having costs inflicted on them. Duntley then elucidates an exciting new co-evolutionary theory of the evolutionary psychology of homicide and homicide defenses—manifestations of human conflict with the most dramatic fitness consequences.
Modern introductory textbooks in psychology are notable for their absence of attention to problems of survival. Perhaps because most view evolutionary theory as optional, they fail to offer coverage of the rich psychology of human survival adaptations. Taken together, the five chapters in this section showcase the scientific gains already made by exploring psychological adaptations to the hostile forces of nature, and offer the exciting promise of many more to come.