In contrast to the stages of development we so far surveyed, aging is a period of life that also brings vulnerabilities and decrements, both physical, cognitive, and emotional. The chapter shows that in the domain of cognitive functions and the brain structures that support them, aging is associated with certain losses that can make cognitiveemotional integration more diffi cult, especially in situations that are complex and diffi cult; in such situations, individuals cannot always rely on the store of their skills acquired in the past, but are required to develop novel ones. In such situations, tension thresholds no longer increase as in periods of development, but are characterized by a lowering. As a result, tension thresholds are lowered and hence reached more quickly, especially if tasks pose complex and stressful demands. By contrast, in well-mastered and well-automated tasks and provided good health, aging also often presents itself as a period in which individuals can reap from the accumulation of their rich experience, such as professional, artistic, or musical expertise, as well as social skills involving knowledge accumulated about life and people. In contrast to literature dealing with losses in cognitive-emotional integration, in such areas of expertise elders can maintain, profi t from, and sometimes excel at, the use of rich world knowledge that supports creativity and wisdom. These developments are illustrated with research examples as well as real-life samples of the thinking and emotions of elders.
The Why, How, and When of Aging and Its OptimizationAging is a universal process of living organisms, and death at the end of one's life is an inevitability. It is not diffi cult to understand that often, aging is surrounded with fearful and negative connotations. Yet whereas growing older results in eventual death, aging itself is not a fi xed phenomenon; in fact, it has dramatically changed over the course of historical time. Indeed, in the book on "The Future of 118 Aging (2007)" 1 we have witnessed a "vitalization" of aging (Gruss, 2007 ) in the sense that elders of today are in better health and more vital than was true at earlier. For example, a contemporary 70-year-old is likely to have maintained much higher levels of mental and physical fi tness that was true some 30 years ago and, in fact, may resemble more a contemporary 60-year-old than an aged individual (Baltes, 2007 ).Why do we humans age? This question has occupied individuals for centuries. Gruss ( 2007 ) points out that aging is not restricted to old age, but in fact begins at the moment of conception that initiates in its turn a chain of transformations. However, these transformations are not optimized for maximal longevity of individuals, but rather, for reproductive success. That these transformations are greatly controlled by genetic mechanisms is evident from the fi nding that different species have widely varying life spans-for example, about 3 years in mice, 60-70 in elephants, and 150 years in giant turtles (Gruss, 2007 ). Ne...