In 1975, De Waal began a six-year project on the world's largest captive colony of chimpanzees at the Arnhem Zoo. The study resulted in many scientific papers, and resulted in publication of his first book, Chimpanzee Politics, in 1982. This book offered the first description of primate behavior explicitly in terms of planned social strategies. De Waal was first to introduce the thinking of Machiavelli to primatology, leading to the label "Machiavellian Intelligence" that later became associated with it. In his writings, De Waal has never shied away from attributing emotions and intentions to his primates, and as such his work inspired the field of primate cognition that, three decades later, flourishes around themes of cooperation, altruism, and fairness.