Maintains that the "getting into shape" hypothesis of explaining the inverted-U distribution of exercise play across age is likely incorrect. Argues that the biological study of human physical activity play, as recommended by Pellegrini and Smith (1998), will reveal whether physical activity play represents an example of…

The contents of this book, an outgrowth of a symposium held at the meetings of the American Association for the Advancement of Science in Washington on December 30, 1966, are organized in three sections. Section one, "Behavior-Genetic Analyses and Their Relevance to the Construct of Race," includes the following essays: "The Construct Race and the…