Origin of the domestic dog as the Tibetan people. A population genetic analysis then showed a significant convergence between humans and dogs in Tibet. Like the Tibetan people, Tibetan mastiffs appear to have derived these benefits partially from the EPAS1 gene, acquired through introgression. In 2015, a study found that when dogs and their owners interact, extended eye contact (mutual gaze) increases oxytocin levels in both the dog and its owner. As oxytocin is known for its role in maternal bonding, it is considered likely that this effect has supported the coevolution of human-dog bonding. One observer has stated, "The dog could have arisen only
Dog capabilities, and physical attributes. Their long association with humans has led dogs to be uniquely attuned to human behavior and they are able to thrive on a starch-rich diet that would be inadequate for other canid species. Dogs vary widely in shape, size and colors. Dogs perform many roles for humans, such as hunting, herding, pulling loads, protection, assisting police and military, companionship and, more recently, aiding disabled people and therapeutic roles. This influence on human society has given them the sobriquet "man's best friend". In 1999, a study of mitochondrial DNA indicated that the domestic dog may have originated