There is mixed opinion on the likelihood of continued long-term increase in life expectancy. Most demographers including Vaupel and Lee (44, 45, 62) are optimistic about continued increases in life expectancy and decreases in mortality among older persons. Olshansky (63) has been a promoter of the idea that future increases will be minimal. The arguments for modest expectations generally rest on the notion that it would take very substantial decreases in mortality at older ages to achieve continued increases in life expectancy, and these would require scientific understanding and an ability to address the basic mechanisms of aging that are unlikely. The argument for continued optimism is that.