Lucy’s legacy and the past and future of primate research

The histories of paleoanthropology and primatology have been deeply intertwined in the quest to understand human origins, dating from Darwin’s bold hypothesis that humans would likely have evolved in Africa from an ancestor that closely resembled the modern apes. However, for much of the 20th century, the relevance of nonhuman primates to anthropology was focused narrowly on what could be learned from anatomical comparisons. The discovery of the “Lucy” fossil, and the challenges it posed to existing narratives about human evolution, came at a pivotal time when a few nascent field studies were beginning to produce similarly remarkable observations about the behavior of primates in the wild. The convergence of these discoveries stimulated a flood of new questions that have catalyzed decades of research on the diverse ways that primates think, behave, and interact with their environments. The significance of this primate research for the field of anthropology is often presented as a solution to a particular problem, that behavior does not fossilize. Yet, the success of this research program in the intervening decades challenges this very premise, in that lessons learned from these living models have progressively strengthened the ability to make inferences about the lifestyle and behavior of our ancestors. Most importantly, studies of living primates situate biological traits within the rich social and ecological contexts that shape their evolution. In doing so, these studies have made their most uniquely valuable contributions to the study of human origins by disentangling the roots of complex social behaviors, such as cooperation, culture, language, and social learning, along with their potential impact on humans’ unique life course adaptations. Along the way, primate studies have become increasingly interdisciplinary and have developed rigorous methods for studying social processes and their impacts on individual biology. Fifty years from the discovery of Lucy, these toolsets that were developed out of our desire to reconstruct the past have gained new relevance for understanding the human condition today.