The areas of the tongue sensitive to tastes. The classical theory about the physiology of taste recognizes the existence of four fundamental tastes - sweet, salty, sour and bitter - each being perceived by specific areas of the tongue by means of gustatory receptors, also known as taste buds.
Theories of Aging. Theories of Aging. Erik Erikson, who took a special interest in this final stage of life, concluded that the primary psychosocial task of late adulthood (65 and beyond) is to maintain ego integrity (holding on to one's sense of wholeness), while avoiding despair (fearing there is too little time to begin a new life course).
Life history theory is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories-including their reproductive development and behaviors, life span and post-reproductive behavior-have been shaped by natural selection.he key to life history theory is that there are limited resources available, and focusing on only a few life history characteristics is necessary. Examples of some major life history characteristics include: 1  Age at first reproductive event. 2  Reproductive lifespan and ageing.