What is healthy aging in the 21st century?

In the coming years, human aging will be one of the biggest challenges faced by industrialized countries. The average life expectancy is continuously increasing and we may be faced with spending more years in poor health. Because aging is a relatively modern phenomenon, we lack knowledge for a proper understanding of this process. Current biological thinking emphasizes that organisms are encoded for early survival and reproduction, humans not excluded. Aging is not programmed nor is it inevitable. Life span is the result of the interactions between genes and the environment in which we live. In the original habitat, genes encoding early survival and reproduction were optimized in an everlasting attempt to increase fitness and prevent the species from extinction. Aging is best explained as a cost of optimizing fitness because investments in body maintenance and repair cannot be maximized. The environment also determines how a gene influencing life span is expressed over a lifetime. When the conditions in which we live significantly improve, mortality decreases, evolutionary pressures for early survival and reproduction relax, and further resources can be invested in body maintenance and repair, which increases both average life expectancy and maximum life span. Increasing our understanding of the aging process and applying available interventions will help to protect and preserve healthy aging.