This book describes the recent advancement of basic research on the biology of aging and longevity studies in various organisms, as well as the neurobiology of aging and neurodegeneration mechanisms. Chapters present new findings and conceptual developments concerning the basic mechanisms of aging and longevity determination. As a follow-up volume to the previous book Aging Mechanisms (2015), it overviews the rapid progress of aging research introducing new topics from leading laboratories in Japan. Chapter contributors are selected based on recent scientific achievements on the mechanisms of aging in various model organisms, including yeast, worm (C. elegans), fly (Drosophila), mice, and rats. Chapters are ordered from the discussion on molecular and cellular levels to physiological and systemic levels. The book also provides an overview of aging science in the region and helps readers quickly grasp who is doing what in this research area. As the aging of population becomes an ever more pressing issue in Asia, advancing the understanding of basic mechanisms of organism aging and longevity determination will be crucial to developing more effective therapies and protective strategies. Researchers and graduate students in biomedical aging research will find this as a rich source of information and a stimulus to novel research directions.