The questions just listed are not just of scientific interest.If, on the other hand, you are convinced of the supreme importance of early experience, then you would intervene as soon as possible, offering high-quality stimulation and support to ensure that children develop at their best.Other theorists, taking a more opti mistic view, see development as having substantial plasticity throughout life-as open to change in response to influential experiences (Baltes, Lindenberger, & Staudinger, 2006; Lerner & Overton, 2008; Lester, Masten, & McEwen, 2006).And a growing number regard heredity and environment as inseparably interwoven, each affecting the potential of the other to modify the child's traits and capaci ties (Cole, 2006; Gottlieb, Wahlsten, & Lickliter, 2006; Lerner, 2006; Rutter, 2007).Hallmarks of this period are improved athletic abilities; partici pation in organized games with rules; more logical thought processes; mastery of fundamen tal reading, writing, math, and other academic knowledge and skills; and advances in under standing the self, morality, and friendship.For many contemporary youths in industrialized nations, the transition to adult roles has become increasingly prolonged-so much so that some researchers have posited a new period of development called emerging adulthood, which spans ages 18 to 25.Because of the need to solve everyday problems concerning children, researchers from psychology, sociology, anthropology, biology, and neuroscience have joined forces with professionals from educa tion, family studies, medicine, public health, and social service-to name just a few.Periods of Development

Besides distinguishing and integrating the three domains, another dilemma arises in discuss ing development: how to divide the flow of time into sensible, manageable parts.2.3.4.5.