It may come as a surprise but this will not be a talk about genetic engineering. In contrast to common belief, human aging is neither biologically nor contextually determined. Instead it is the result of continuous interactions between biological and sociocultural forces. This is why an individual’s aging trajectory in a given domain of functioning can within biological limits take many different shapes. This intraindividual variability has been labeled the ‘plasticity of human aging.’ Examples from cognitive and personality functioning are presented to illustrate the plasticity of aging and its limits. Given the plasticity of human aging, it is worthwhile compiling more and more scientific knowledge about which characteristics of sociocultural contexts are optimal for slowing biological aging and help compensate for genetic vulnerabilities. Cohort- and country-comparative longitudinal data including physiological as well as behavioral performance measures besides sociodemographic information are needed to gain a deeper understanding of human aging.