Humans have bred dogs for physical and behavioral characteristics for millennia. These efforts can have unintended side effects, however, which may be either advantageous or cause issues - such as a predisposition to certain medical complaints, or, controversially, behavioural issues. The scientific study of domestic dogs is still in its infancy, but public demand for this information is at a record high as more and more pet owners seek to understand their canine family members. Focusing on the behavioral differences and tendencies that have arisen in different breed lines, this book explores, summarizes, and explains the scientific evidence on what breed can tell us about behaviour - and, crucially, what it cannot. This book covers: - the impact of inbreeding, how it contributes to problematic behavioral issues such as anxiety and aggression, and how it potentially affects the future health of the breed; - the limits of predicting a dog's behavior based upon breed, individual differences within breeds, and thus the corresponding limitations of breed-specific legislation; - guidance for professionals to help their clients better understand behavioral issues, traits, and appropriate expectations around the right breed for their household. Providing a comprehensive and approachable view of the science behind breed-specific behaviors, this book gives dog enthusiasts from all professional and personal backgrounds a better understanding of why dogs do what they do, and how we can improve our relationships with our canine companions. Covering genetics, phylogeny of canids, temperament, aggression, social behavior, and the history of dog breeding, it is an important read for researchers, students, veterinary practitioners and animal behaviourists, as well as shelter staff, dog trainers, or anyone looking for a greater understanding of dog breed differences.