You are probably very familiar with your dog's suspiciously nosy behavior, especially when a food source is nearby. This behavior originates back when dogs were hunters and scavenged, or searched, for food left behind by other animals. Once domesticated and part of our families, they continued to scavenge for food, just in a lesser degree.
According to the Association of Pet Dog Trainers, dogs originated as scavengers. Scavengers are typically carnivores, and sometimes herbivores, that search for a free meal left behind by others, such as wolves, bears, lions or even humans. Dogs are opportunistic scavengers, meaning they feed on food from different sources as it becomes available.
Dogs' history of scavenger-like behavior is still apparent today. For example, if your dog has the run of the house while you step out, you may come home to find he has rummaged through your garbage or left evidence behind that he sniffed around your kitchen countertop in search of a free meal. Or, while your dog is out playing in the yard or on a walk, he may become distracted and scavenge around in piles of leaves or under bushes.