How did we do it? What gave us such a huge advantage over our competitors?

I've got one suggestion: dogs.

In the last few years, paleontologists have produced remarkable evidence that dogs are not only our "best" friend but also our oldest friend. Just how old has been surprising. In 2009, a team led by Belgian paleontologist Mietje Germonpre produced compelling evidence that the oldest domesticated dogs yet known came from Goyet Cave, a site in Belgium. That in itself is not startling. What was startling was the radiocarbon date on the dog remains: about 32,000 years ago—a good 20,000 years earlier than any other domesticated animal.

As is often the case with surprising results, not everyone was sure at first that the results obtained by Germonpré and her team were correct. But the of the Goyet dog has now been confirmed by another radiometric date and the statistical analysis of the size and shape of the skulls and teeth that identified the Goyet dog and two others as domestic dogs, not wolves, is unimpeachable.

Very recently, the team enlarged their sample of fossil canid skulls, to see if the large gap between the Goyet dog and the next oldest fossil dog, at about 17,000 years ago, could be filled in. After all, if dogs were domesticated at 32,000 years ago, there should be dog remains in the subsequent 15,000 years, right?

Studying nine more ancient skulls, they confirmed three more were ancient dogs, from Prĕdmostí, in the Czech Republic, a site dated to about 27,000 years ago. Two more were ancient wolves, and four did not group strongly with either dogs or wolves. Intriguingly, these four skulls might have been wolf-dog hybrids.

Another canid skull with many doglike features was studied recently by Siberian scientist Nicholai Ovodov and his team. It comes from Razboinichya Cave, Siberia, and dates to the same age as the Goyet dog. This team did not use the same powerful statistical techniques as Germonpré's group, but they concluded that the Razboinichya skull is an "incipient dog"—an animal in an early stage of the domestication process—because it shows also shows some features they judge to be more wolflike.

All this research makes clear that dogs were domesticated by at least 32,000 years ago. And, although Neandertals were living and leaving sites in Europe during the same time period, all of the ancient dogs come from sites with stone and bone tools that are unmistakably of the types associated with modern humans, not Neandertals.

Why Neandertals didn't domesticate dogs is an open question. Neandertals had survived for millennia in a tough environment. Why were they unable to domesticate wolves and transform them into dogs? Maybe they lacked the requisite ability to empathize with another species, but Neandertals were good hunters which requires an ability to observe and understand the prey's habits. Maybe they tried to domesticate wolves—maybe they saw how useful those funny-looking "wolves" were to modern humans—and yet through the random process known as dumb luck, they simply didn't succeed. We just don't yet know.

Let's step back and ask: how much difference domesticated dogs would have made to our ancestors? Quite a lot. Because there are limb bones and in some cases whole skeletons of the dogs at Prĕdmostí, Germonpré's team was able to calculate their body size with some accuracy. These were big, hefty dogs, ranging from 75 to 90 lbs and at least 2' tall at the shoulder-about the size of modern German shepherds. Though they were not quite as large as modern Eurasian wolves, but they were powerful animals.

What advantage would such dogs have offered our ancestors?

Taking a clue from the other animals found at the same sites as the fossil dogs, Germonpré and her team suggest these dogs might have been valuable as beasts of burden. With the exception of the fossil assemblage from Goyet Cave, every other early dog site is dominated by mammoth bones—the biggest prey animal alive at the time. For example, at Prĕdmostí, 75% of the remains are elephant bones, amounting to at least 1000 individual mammoths. Among other things, this fact establishes that our ancestors were not only killing a lot of very, very large animals, they were moving the carcasses around the landscape. Large canids are the second most common animal at Prĕdmostí and represented at 103 individual animals.

A mammoth represents a truly enormous amount of meat, enough to feed a sizeable group for some time, particularly in cold climates where meat can be frozen. (A live mammoth weighed approximately 12,000-16,000 lbs, bones included.) Killing a mammoth is in itself a formidable task, but how do you get a mammoth home once you've killed it? No horses or oxen, no carts, no wheels. You've got no choice. You just plain cut the mammoth up and lug it home in pieces. And large, strong dogs pulling meat and bones tied onto a simple device like a travois or even bundled onto a large hide would be an amazing help.

Even if you weren't taking such colossal prey, the value of pack animals would be huge in transporting other common prey, such as wild horses or elk (known as red deer in Europe). If a Neandertal killed an elk weighing "only" about 1,000 lbs, he'd have to lug home probably 500 lbs of that after rough field butchering. Such as task ewould be time-consuming and exhausting. Since I lived for years in rural central Pennsylvania, I know that modern deer hunters all too often suffer heart attacks dragging the 100-lb carcasses of white-tailed deer back to the truck. If an ancient but modern human of the time killed a bigger animal like an elk, he'd only have to cut it up and let the pack of pack dogs carry it home. Dogs could carry equipment for hunting and living, firewood, meat, or even full water containers.

Dogs the size of a husky or German shepherd can carry packs up to almost 50 lbs in weight. Some anthropologists have argued that, without pack dogs, humans could not have settled the far northern regions of the world or gotten to North America. Certainly relieving humans of the literal burden of transporting such large prey would change their energy budget considerably.

But transport is not the only benefit a large dog offers. The extensive written records of hunting in medieval Europe show that large dogs called lymers were used to track prey by smell or to surround stags or other large animals and keep them in one place while hunters approached. (Sight hounds, like greyhounds, tend to be smaller than hounds.) With ferocious, aggressive animals like wild boar, heavy dogs were sometimes trained to seize them by one ear to immobilize them. With well-trained dogs, medieval hunters could bring in tens of deer, elk, or boar in a single day.

We should not forget one of the real benefits of dogs; they are warm and soft and companionable. And, because dogs are territorial, their barking helps alert the humans to the presence of any wolves or other large carnivores in the area, just as today dogs warn Alaskans of hungry polar bears.

Yes, a dog was a supremely valuable friend, then as now. Looking into the past shows us just how crucial they probably were to the survival of our species. Perhaps that close, ancient connection with dogs is why they appear so rarely in prehistoric cave art, which rarely depicts people. However, the teeth of canids were commonly pierced to wear as jewelry and some of the ancient dog skulls show signs of ochre, implying some sort of ritual was carried out after the death of a dog. Maybe early dogs were considered to be more human than animal. The past is not always so different from the present after all.