A 2009 study published in the Molecular Biology and Evolution journal cites an analysis of ancient dog mitochondrial DNA that suggests they evolved alongside wolves “over 100,000 years ago.” Thus, many experts believe canines began scavenging due to a lack of food, and that humans slowly developed a bond with these animals that also acted as early warning alarms if larger creatures approached a campsite or entered a cave. Some scientists believe wolves and early humans hunted together and this is how the relationship was formed.