Why have dogs doubled in weight in 6,000 years?

The evolutionary history of Man is intimately linked to that of the dog, both biologically and culturally. The first clues of domestication of these canids date back more than 30,000 years and the common association, in the register fossil, between man and dog, dates back approximately 15,000 years. Many fossils of dogs have already been discovered and allow us to understand the morphological evolution of thespecies. However, knowledge of the factors that influenced the evolutionary trajectories from the first dogs to the current forms remains very fragmented.

Besides the lack of fossils, this knowledge is incomplete due to the fact that the domestication of the dog has occurred independently in several places in the world and was probably initiated according to different behaviors and objectives. A study conducted by an international research team was the subject of a publication in the Journal of Archaeological Science: Reports about the morphological evolution of dogs in Croatia since the Neolithic.

Dogs to guard the flocks

The authors of this study inferred the height of dogs between about 8,000 (Neolithic and Stone Age) and 2,000 years ago (Roman period). The remains of more than fifty dogs mainly from Croatia but also from neighboring European countries were examined. The first Neolithic farmers arrived in Croatia from Anatolia (Asia Minor) and the Middle East and presumably brought with them a breed of dogs which was not already present in this region. The authors report that specimens of this newly imported breed weighed around 15 kilograms.

About two thousand years later, during the Bronze Age, the average weight of dogs had increased by two kilograms while they reached the average weight of 24 kilograms during the Roman period. The authors suggest that larger and larger dogs were bred over time to protect livestock from predators. Sheep herds were indeed grazing at higher altitudes and were therefore probably more vulnerable to large predators such as bears and Wolves. There are also documents in which Romans give advice to breeders about sheepdogs. From these documents, it was estimated that the dogs could even reach the average weight of 32 kilograms and therefore probably rivaled today’s sheepdogs in weight.