Early roles

Wolves, and their dog descendants, would have derived significant benefits from living in human camps—more safety, more reliable food, lesser caloric needs, and more chance to breed.^[37] They would have benefited from humans" upright gait that gives them larger range over which to see potential predators and prey, as well as color vision that, at least by day, gives humans better visual discrimination.^[37] Camp dogs would also have benefited from human tool use, as in bringing down larger prey and controlling fire for a range of purposes.^[37]

Humans would also have derived enormous benefit from the dogs associated with their camps.^[38] For instance, dogs would have improved sanitation by cleaning up food scraps.^[38] Dogs may have provided warmth, as referred to in the Australian Aboriginal expression "three dog night" (an exceptionally cold night), and they would have alerted the camp to the presence of predators or strangers, using their acute hearing to provide an early warning.^[38]

Anthropologists believe the most significant benefit would have been the use of dogs" robust sense of smell to assist with the hunt.^[38] The relationship between the presence of a dog and success in the hunt is often mentioned as a primary reason for the domestication of the wolf, and a 2004 study of hunter groups with and without a dog gives quantitative support to the hypothesis that the benefits of cooperative hunting was an important factor in wolf domestication.^[39]

The cohabitation of dogs and humans would have greatly improved the chances of survival for early human groups, and the domestication of dogs may have been one of the key forces that led to human success.^[40]

Emigrants from Siberia likely crossed the Bering land bridge with dogs in their company, and some experts^[41] suggest the use of sled dogs may have been critical to the success of the waves that entered North America roughly 12,000 years ago,^[41] although the earliest archaeological evidence of dog-like canids in North America dates from about 9,400 years ago.^[34]:104[42] Dogs were an important part of life for the Athabascan population in North America, and were their only domesticated animal. Dogs also carried much of the load in the migration of the Apache and Navajo tribes 1,400 years ago. Use of dogs as pack animals in these cultures often persisted after the introduction of the horse to North America.^[43]