Despite unprecedented investments in public health and biomedical research, improvements in life expectancy and healthy life expectancy have stagnated in the United States. Part of the reason for this development can be traced back to the influence of "Protean" over "Post-Protean" public health, the names that can be given to two contrasting visions of public health advanced in the early twentieth century. Protean public health prescribes "waging a war" against disease and was successful in reducing the early-life mortality risks from infectious disease. But Protean public health has proven less effective in improving the quality of life of older persons. Post-Protean public health prioritizes the experimental method and research into the indirect methods of improving health. It articulated a vision of public heath that was given a more concrete specification by Alex Comfort in what is now referred to as the Geroscience Hypothesis. To improve the health prospects of aging populations the dominance of Protean public health must be relaxed, to enable the benefits of Post-Protean public health to be realized. Doing so means shifting public health's aspirations towards increasing the healthspan vs "saving lives" by extending the duration of time older persons can survive by managing the multi-morbidities of late life.