Let's be honest: left to our own devices, we humans aren't very effective carnivores. We're big and awkward, we don't have talons or other sharp appendages, we have relatively weak jaws, and our sense of smell isn't anything to write home about (and then on top of that we're bipedal, so our noses aren't close enough to the ground to track a scent). Yet somehow, our brains evolved to require a massive amount of protein—something we couldn't reliably get by foraging. On paper, it looks like dumb luck that homo sapiens didn't die off when homo neandertalensis did.
Scientists have long speculated that we made up for our limitations with our tool-making skills and capacity for language, but a recent study of a mammoth kill site by Penn State anthropologist Pat Shipman suggests that man's best friend may have also been essential to, well, man's survival:
[I]n addition to complex projectile technology, an alliance or collaboration between modern humans and domesticated or partly-domesticated large canids best explains the appearance of mammoth megasites, including the high numbers of individual mammoths and canids at such sites and the close proximity of sites to the place of mammoth death. The advantages of projectile technology and canid collaboration may have led to the survival of [anatomically modern humans] while Neanderthals went extinct.
The idea that the domestication of dogs contributed to human civilization is not an unpopular one. The BBC's The Secret Life of the Dog quotes several prominent anthropologists who make the well-grounded claim that the domestication of dogs made humans efficient hunters, ultimately making it possible for our species to largely transition from foraging to subsistence agriculture (and, subsequently, settlement into permanent communities, city-states, nations, and empires):
Wild dogs can be found on every continent except Antarctica, so there is—in principle—no reason why dogs could not have been associated with every human community at some time or another, their domestication as much a part of the prehistoric extended human phenotype as tools and clothing.