12,000-year-old canine tibia (IMAGE) University of Arizona Caption The jawbone and the leg bone, seen here in a composite scan, both showed substantial contributions from salmon proteins in lab testing, leading researchers to conclude that humans had fed the fish to the dogs. Credit François Lanoë/University of Arizona School of Anthropology Usage Restrictions This visual may only be used in the context of reporting on the research referenced in this news release. Credit must be provided as indicated. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.