Introduction: Gorilla biology: Multiple perspectives on variation within a genus

It is perhaps widely appreciated in the realm of primatology that until fairly recently, our perspective on gorillas has been an unbalanced one. Our earliest and most comprehensive accounts of gorillas in the wild can be traced almost entirely to studies of the East African gorillas of the Virungamountains,Gorilla gorilla beringei or, as it is now being called by some,Gorilla beringei beringei, even though explorers’ initial contacts were with the gorillas of West Africa. This is not unlike our early view of the chimpanzee, which for the better half of the twentieth century was based primarily on the chimpanzees of Gombe and the work of Jane Goodall, or our early view of the orangutan, which for years was informed by work conducted at only a few sites along the Bornean coast. Pioneeringwork bywell knownfield primatologists, such asGeorge Schaller and Dian Fossey, provided the first systematic accounts of gorillas, cementing in our minds the image of these animals as plant-eating, quadrupedal, terrestrial knuckle-walkers. As a testimonial to the one-sided nature of these early gorilla field studies, the first important attempt to document the behavior of the western lowland gorilla is briefly noted by Schaller in the Preface to the Phoenix Edition of his landmark study The Mountain Gorilla, as “an interesting report on the little-known West African gorilla”. Ironically, the gorillas of West Africa, that proved to be so difficult to study in the wild, provided the basis for the earliest and most extensive anatomical descriptions, creating a long-standing disconnect between their behavior and morphology that has taken decades to reconcile. It is worth pointing out that the eastern lowland gorillas, subsumed within the subspecies Gorilla gorilla beringei by Coolidge in 1929 and classified as such for 40 years, went virtually ignored in the wild until the tail end of the twentieth century. Research conducted over the past 25 years has begun to redress the imbalance created by unilateral studies of western lowland gorilla morphology on the one hand, and eastern mountain gorilla behavior on the other. Thus, our objectives were twofold. One aim was to fill a notable gap in the primatological literature, resulting from the scattered accumulation of important gorilla research that has been conducted during the past several decades, and to assemble this information in a detailed and integrated framework. Our second objective was to emphasize an interdisciplinary and comparative approach to