Twenty years of progress in biogerontology research.

The first 10 years of NIA's existence were characterized by funding for descriptive and discovery research, as the field had not yet come of age. As Couzin expressed it in the July 1, 2005 issue of Science, "Just 2 or 3 decades ago, research on aging was a backwater" (Couzin J 2005 How much can human life span be extended. Science 309: 83). With the isolation of long-lived animal mutants and the application of the tools of molecular biology and transgenic technology to biogerontology research, the situation has changed dramatically since then, and aging research has become increasingly mechanistic and respectable. This transition has been aided by some well-thought out research initiatives by the NIA, and the purpose of this article is to provide a brief summary of the progress made in the past 20 years, and describe the part that NIA initiatives and funding have played in this transition.