A hypothesis is presented which offers an explanation of how and why the mechanisms of aging and oncogenesis arose. The first Metazoa on Earth did not have these pathological processes, but their evolutionary precursors were contained in their normal ontogenesis programme. The disruptions observed in aging and cancer are atavistic adaptive morphogenetic responses of the first Metazoa on Earth. The views of the immortalists are discussed. The formation in the course of evolution of the property of aging in systems ranked higher than the organismal systems is considered. The paper is written on the basis of previously published articles by the author.