The genetic basis of natural variation in sociability

Abstract Sociability, defined as individuals’ tendencies to affiliate with conspecifics, is widespread among animals, including species not traditionally categorized as social. A few studies have documented a positive association between sociability and fitness, and sociability has positive effects on health, well-being, and longevity in humans. Despite the importance of sociability, we still have limited information about its genetic basis. To address this knowledge gap, we compared gene expression in the heads of fruit flies (Drosophila melanogaster) from lineages artificially selected for, and divergent in, degree of sociability. We identified 174 genes that showed differential expression among low and high-sociability lineages, of which 33 genes have known effects on neuroanatomy, neurophysiology, or behavior. Experiments using knockdowns of 16 of the top candidate sociability genes revealed 6 of them significantly affecting sociability in the predicted direction. Relying on our large genomic database, we and others can further elucidate the genetic architecture and evolutionary biology of sociability.