Suresh I.S. Rattan, PhD, DSc, is an internationally renowned biogerontologist at the Laboratory of Cellular Ageing, Department of Molecular Biology and Genetics, Aarhus University, Denmark. He is one of the pioneers for the testing and application of hormesis in aging research and interventions. His research expertise includes elucidating the molecular mechanisms of human cellular aging. Dr. Rattan is the discoverer of the aging-modulatory effects of kinetin and zeatin, which are now used in several skin care products. He is the editor-in-chief of the journal Biogerontology. He has published numerous original research papers and reviews, and is the author of popular science books for children in several languages. Éric Le Bourg, PhD, DSc, is an internationally renowned biogerontologist at the French National Center for Scientific Research (CNRS), Université Paul Sabatier, Toulouse, France. He is well known for his studies on the effects of mild stress in Drosophila but is also working on learning, behavior, and demography matters. He has published numerous papers and has written several books on aging in French for the lay public and academics on the biology, demographic, and social matters. Both editors have previously collaborated and edited the book Mild Stress and Healthy Aging (Springer 2008) and brought out two special issues of the international peer-reviewed journals Biogerontology (2006) and Dose Response (2010).