Understanding Very Old Age: Looking Back and Thinking Forward.

Understanding human development among the oldest old is a sequential building process taking into account building-block data, theories, and models from childhood, adulthood, and old age toward a new territory of oldest-old survivors who have lived way beyond the average life-span. A central question is whether the oldest-old survivors have developed specific survival techniques and/or protective environments that nurture survival. Or are the oldest old statistical outliers who by happenstance continue to survive further into old age? This commentary provides a historical framework on the papers in this series that describe challenges confronted by the oldest-old survivors in order to advance our understanding of survival of the oldest old. A clear understanding of the contributors to longevity could guide public policies toward well-being and life satisfaction among our oldest-old citizens.