Frans X. Plooij, PhD, has been conducting research in the field of psychology for close to 50 years. Highlights include working alongside his wife, Dr. van de Rijt, with Dr. Jane Goodall on infant development in free-living chimpanzees in the Gombe National Park; leading the department of Research and Development at the institute for Child Studies of the City of Amsterdam; and currently presiding over the International Research Institute on Infant Studies (IRIS) at Arnhem, the Netherlands. He is a full member of several international scientific societies in the domains of child development and behavioral biology and of the New York Academy of Sciences.