This lesson will give you an overview of the major human development theories. Adult and Older Adult Development Theories Human Growth and Development Theories. Adulthood Age Group Growth & Development Lecture itinerarte.info 2 full adult independence. This seems to have created a new phase which can be called emerging. Human growth and development; Stages; Human Human development is the process of growing this entails growth from a one-celled zygote to an adult human.