In the broad sense, modern humans have lived in an environment in which physical activity and associated movement skills were central, especially in the context of physical competition with other animals. The physically active lifestyle of earlier human populations has been emphasized, especially the cardiovascular endurance component and energy expenditure, but less attention has been devoted to the gross and fine motor skills that are essential components of this lifestyle. Motor skills developed through practice are important determinants of success and survival in preindustrial societies. In industrial and postindustrial societies, on the other hand, the role of physical activity is different, with prowess in certain areas of physical expertise (e.g., accuracy with projectiles, muscular strength, among others) and prolonged exertion (i.e., cardiovascular endurance) less important for survival. The combined effects of the transition to a sedentary lifestyle and attendant dietary changes have resulted first an epidemic of coronary heart disease and more recently an epidemic of overweight/obesity in postindustrial societies. Although mortality associated with coronary heart disease has declined, due largely to biomedical advances, overweight and obesity have increased concomitantly with population reduction in physical activity (energy expenditure) and increased calorie (energy) consumption. The current scenario begs several questions which have implications for contemporary human biology related to sustaining the pace of cultural change on a biological base that is increasingly being compromised by physical inactivity, overweight, and obesity. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc.