This document summarizes several key theories of human development, including:
1. Nature and nurture influence development through heredity and environment. Development progresses from simple to complex cognition and biological maturation.
2. Prenatal development occurs in three periods - germinal, embryonic, and fetal - involving cell growth and differentiation.
3. Infancy and childhood development involves achieving motor skills and cognitive milestones while navigating hazards like illness, accidents, and malnutrition.
4. Adolescence brings puberty, physical changes, and psychological adjustments. Adulthood has early, middle, and late stages each with physical and social challenges.
5. Biological theories propose aging results from cellular lifespan limits, free radicals