New evidence suggests that it was the domestication of the dog that supported modern man's evolutionary triumph over the Neandertal alternative:
Would a good dog really have been so important that it would inspire ritual significance—and give modern humans a crucial edge over Neandertals? We can’t observe how ancient, but anatomically modern, humans used dogs in their daily life, but there are some interesting possibilities. We know from their bones that the Paleolithic dogs were very large, with a body mass of at least 32 kilograms and a shoulder height of at least 61 centimeters, about the size of a modern German shepherd. Germonpré and her colleagues suggest that these early dogs might have been beasts of burden. They cite ethnographic examples of peoples like the Blackfeet and Hidatsa of the American West, who bred very large, strong dogs specifically for hauling travois or strapped-on packs.
All but one of the six Paleolithic dog sites that have so far been identified preserve large quantities of mammoth bone which, with meat attached, must have been lugged from the kill site to where the group was living. If the dogs carried the meat, humans would have saved a lot of energy, so each kill would have provided a greater net gain in food—even after feeding the dogs. Additional food generally has marked effects on the health of a group. Better-fed females can have more babies, can provide them with more milk and can have babies at shorter intervals. Before long, using pack dogs could have caused the human population to increase.
Dogs may also have contributed more directly to human hunting success. To discover how big a difference dogs could make, Vesa Ruusila and Mauri Pesonen of the Finnish Game and Fisheries Institute investigated what may be the closest easily studied analog to a mammoth hunt: the Finnish moose hunt. Finns use large dogs such as Norwegian elkhounds or Finnish spitzes to find moose and keep them in place by barking until humans can approach and shoot them. In hunting groups of fewer than 10 people, the average carcass weight per hunter without dogs was 8.4 kilograms per day. With dogs, the yield went up to 13.1 kilograms per hunter per day—an increase of 56 percent.
(h/t Jonathan Foreman)