At the beginning of this section we referred to the physical, psychological, and social aspects of middle adulthood. These have ranged from minor physiological changes to the way that knowledge of our own mortality may influence how we behave and feel during this part of the lifespan. The central theme might be identified as that of connection—the way that the body and mind are connected, how one can effect the other, exemplified by the way that physical mobility can impact cerebral acuity. In addition, we have learned that we are more selective in regard to interpersonal connection as we age. The positive aspects of relationships, work, and family assume ever greater importance. Hope is ever present, but these sorts of positive and fulfilling connections cannot be postponed indefinitely. Freud believed that civilization was only possible if humans could be induced, or trained, to defer immediate gratification. That was what the process of primary childhood socialization was about. Perhaps middle adulthood demands that we unlearn this, if only partially. At this stage of the life course, it is now or never. Time is finite and there is none left for indefinite postponement. This is what modern developmental theory has come to understand as mortality salience.

Developmental perspectives have tended to view intimacy and familial relationships as a universal need and function. It has largely left their transformation by divorce, cohabitation and so forth to the sociologists. However, there is now a clearer understanding of the way that structural economic and social change have impacted family structures, often in those least able to resist the disruptive effects of social inequality (Cherlin, 2014). Income and education levels play as large a part in all of this as lifestyle choices, and selectivity. We can only hope that advances in medical science can lead to greater quality of life at this stage of the life course, and that they are made widely available.