The geographer Jared Diamond has called domestication the worst mistake humans ever made. He blames domestication for the rise of monoculture, which he says leads to a larger, more sedentary human population in which disease can spread rapidly. On top of that, settled populations dependent upon crops become more vulnerable to climate change, plant diseases and natural disasters. Domestication, Diamond says, also caused a precipitous decline in biodiversity, and a rise in social inequality and warfare among humans.

Sounds like a pretty bad choice.

And yet, the first domestication—the turning of wolves into dogs—was an impressive feat. Humans at the time had to evaluate each new species they encountered: Will it kill me, or can I kill it? If it kills me, how is it stronger or more skillful than I? If I kill it, what can I gain?

Eventually, humans began to appreciate that not killing, but living with, another species could be useful. Paradoxically, our ancestors chose one of the most dangerous predators they knew to try to live with: the gray wolf. I'm a paleoanthropologist who has been researching the effects of domestication. The origin of dogs is contentious, but I hypothesize that domesticating wolves into dogs may have helped the first modern humans to outcompete other hominins like Neandertals.

What was the advantage of cooperating with wolves? Modern wolves have greater endurance than humans and a top speed of up to 40 miles per hour, versus 30 to 45 mph in dogs and only 27 mph in a world-class runner like Usain Bolt. Compared with humans, wolves have a superior sense of smell (they have more than 50 times the smell receptors), sharper teeth and claws, and better night vision. Borrowing or co-opting these abilities provided a substantial improvement in humans’ hunting and survival. But the wild wolf had to benefit from the arrangement. The main advantage to the canids would have been that their role was to find the prey, track it and surround it while humans with distance weapons did the dangerous job of bringing a prey animal down and killing it. In independent studies, Karen Lupo and Jeremy Koster have shown that hunting with a dog yields more meat per hour of effort than hunting without one, despite the fact that the dogs eat some of the meat.

Domestication is not taming, like that used with wild-born Asian elephants, which must be laboriously trained anew with each generation. In fact, most animals that humans have attempted to domesticate have refused. A striking example is the beautiful zebra, which, though closely related to the domestic horse and donkey, remains one of most dangerous animals in the zoo.

Because domestication of any animal involves selection (by humans) for genetic traits, it takes generations to accomplish. Some scholars see the earliest changes about 30,000 years ago, while others see domesticated dogs only by about 16,000 years ago. Remarkably, humans tried to domesticate not only the gentle or tasty animals, like cows and sheep, but also fierce competitors vying with us for food, water and safe places to raise their young. I hypothesize that allying with wolves allowed modern Homo sapiens to outcompete and out-survive earlier species like Neandertals who had lived successfully in Europe long before modern humans got there. I see no startlingly large change in weapons in the earliest modern human sites that would account for their survival. Dogs would have helped modern humans not only in hunting but also in guarding the carcass from scavengers after the kill.

Dogs excel at an unusually broad set of tasks: acting as companions; as haulers of loads; as guardians and living weapons; as detectors of disease or contraband; and as trackers. They provide fur, meat, potentially useful bones for making tools, and more dogs. They are especially good at being living blankets. Dog bones or teeth have also served as jewelry, identifying members in a particular human group. Despite the inherent risks of associating closely with another large carnivore, this versatility may have spurred the proliferation of dog breeds in the 18th and 19th centuries. In fact, one’s job or social status has long been signaled by the dog one owns, from the Pekingese of Chinese royalty to the saluki, the racing dog of Egyptian kings, the corgis of the late Queen Elizabeth II, and the sheep-guarding great Pyrenees.

So, why is the origin of dogs contentious? We don’t know how to define what a dog is. First, there is no single trait that we can observe in modern or ancient canids that marks them as dogs. Dogs have a look about them and familiar behavior, but no single definitive trait. Genetically, the number of genes that makes a dog a dog is hard to quantify, even if we have the whole genome of a specimen. For example, in maternally inherited mitochondrial DNA, there are about 16,000 base pairs. How many genes must be sequenced to identify a species? We don’t know because there are mutations that occur but don’t have much effect. How many must be changed to make the specimen no longer a wolf but a dog? Basically, we don’t know.

Second, there is a fundamental problem with dating the progression of wolf to dog. If the specimen is less than 50,000 years old, bones, charcoal and other organic substances can be dated based on the percentage of radioactive carbon that has degraded to a nonradioactive nitrogen. Geneticists use the number of mutations in the genome to date specimens, but mutations may occur faster or slower than “normal.” Genetic dating is not precise. Importantly, not all animals get preserved as fossils, so much of the record of life on earth is invisible.

Finally, I fear we have neglected part of the evidence—where the iconic Australian dingo fits in. After evolving in Africa, modern humans reached Australia before they reached Central Europe, the Americas or Antarctica. Madjedbebe, the earliest archaeological site in Australia, is dated to about 65,000 years ago. Researchers who accept this date can find no trace of dogs or any domestic canids anywhere in the world at this time. Genetic estimates suggest that dingoes got to Australia up to about 18,000 years ago, but there are no dingo bones earlier than about 4,000 years ago. Could they have been in Australia so long and left no traces?

Dingoes figure prominently in the Indigenous culture and mythology of Australians, but dingoes or their ancestors are not marsupials, like every other large-bodied mammal endemic to Australia. (Every placental mammal in Australia—true dogs, horses, rabbits, cats and rats, for example—has been brought in by people.) Sadly, many researchers investigating the origin of dogs have discounted dingoes as unimportant, but they are the only alternative story of the transformation of wild canids into dogs that we have. Dingoes’ distinctive traits are fascinating. Why do they climb and manipulate objects with their paws so well? Why do they howl but not bark? Why do they reproduce only once a year like wolves and mature slowly? Why are they so resistant to being in captivity? What makes dingoes different from dogs? Was it how the Indigenous people of Australia lived, leading to a different sort of domestication, as Adam Brumm and Loukas Koungoulus have suggested? Was it the isolation from other canids? Did dingo ancestors have something lacking in later canids?

We take for granted the origins of this species we hold so dear. But to really understand what a dog is, we need to ask more questions.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.