“In the beginning, there was First Wolf and First Human,” states the first line of the Ojibwe creation story. It goes on to describe the good life they had, romping together in the meadow, napping side-by-side in the afternoon sun, and hunting and feasting together.

The fact that proto-Wolves and proto-Humans procured and shared the same food is not only a theme in the traditional legends of the Ojibwe and many other indigenous peoples, but it is supported by anthropological research. And it changed the trajectory of Human evolution. We’ll get to that amazing story and the science behind it in a moment, but first I’d like to point out why it is particularly relevant to us in this day.

Proponents of healthy diets ranging from vegan and vegetarian to paleo and carnivore often cite the diets of our early Human ancestors to support their arguments for the foods they deem best suited for us. What is usually missing is concrete anthropological and anatomical evidence. As well, there is a significant influence on our ancestral diet that is seldom, if ever, mentioned—Wolf.

Let’s start with a look at who is commonly accepted as the most likely first protohuman ancestor: Australopithecus, who lived between two and four million years ago. Of the eight species of Australopithecus discovered to date, afarensis—the species that the famous 1974 fossilized skeleton discovery named Lucy belongs to—is most widely regarded as our direct ancestor.

Afarensis males were just under 5 feet (150 cm) tall, and females were close to 3 1/2 feet (105 cm) in height. Males weighed in at around 90 pounds (42 kg) and females went 65 pounds (29 kg) on average. That is a rather extreme case of sexual dimorphism, which is a story for another time. Right now, we want to focus on other features of afarensis. To help compensate for small size, afarensis retained the long, curved toes of their forest-dwelling ancestors, most likely to facilitate quick tree climbing in the face of danger.

Although afarensis were bipedal, they still retained the semi-erect posture and bent hips and knees of their tree-climbing forebears. Those features restricted afarensis’ ability to walk and run quickly and efficiently, which translated to low endurance and limited range. Later Hominins had the height and fully erect bipedalism that allowed them the range of movement over the landscape to take advantage of a much more varied and nutrient-rich diet.

Afarensis were almost exclusively vegetarian. We know that about them because of the carbon and nitrogen isotope deposits on their teeth. Plant foods are carbon-based and animal foods are nitrogen-based, so an isotope analysis gives us a fairly accurate picture of the percentage of plant and animal matter in an animal’s diet. Specifically, the higher the ratio of 15N to 14N nitrogen isotopes, the higher the content of protein in the diet. Considering afarensis’ low nitrogen isotope ratio and their limited mobility, the only animal protein they likely consumed was insects, bird eggs, and whatever occasional small animals they could catch.

Here is where Wolf enters the picture. At best, afarensis could only have had a secondary relationship with Wolf, as one of the scavengers coming around either after Wolves abandoned their kill or chasing Wolves off of the kill. That scavenging may have made it possible for afarensis to consume more protein and fat, which allowed for the increased brain volume, body size, and level of bipedalism needed to follow Wolves and the ungulate herds.

The Wolf-Hominin relationship grew from there, to the point where the two began hunting together. That catalyzed the convergent evolution of the two lineages. Two million years ago, Canis etruscus, the immediate ancestor of the Gray Wolf, coexisted with Homo erectus, our immediate ancestor. Unlike afarensis, Homo erectus—as the species name implies— had vertical posture and long legs, and they were up to 6 feet (180 cm) tall, which made them capable of the long-distance running needed to hunt open-country game alongside Wolf.

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In line with convergent evolution, the modern Gray Wolf (Canis lupus) and contemporary Human (Homo sapiens) appeared on the scene at around the same time. The earliest Gray Wolf fossils found to date are 400,000 years old, and the oldest discovered Homo sapiens remains are dated at 300,000 years.

All told, our ancestral lineage has been consistently consuming meat in significant quantities since its transformation into carnivores at the beginning of the Pleistocene Epoch (Ice Age) which was 2.6 million years ago. During the Late Pleistocene, which began 125,000 years ago, we Homo sapiens coexisted and interbred with our Homo neanderthalensis and Homo Denisova (prop) cousins across Eurasia. All three of us had a close relationship with Wolf: we lived in proximity to each other, traveled and hunted together, and shared a hunt-based culture along with a high-meat-content diet.

Recent research shows the typical historical and contemporary hunter-gatherer diet to be more than half meat. One example is the traditional Inuit diet, which is 70 to 80% meat. The Neanderthal diet was over 80% meat. Archaeological evidence shows that even after our kind started to abandon the hunter-gatherer lifestyle for herding (around 11,000 years ago), we continued with our meat-centered diet.

In summary, we appear to be carnivores to the core: evolutionarily, morphologically, and metabolically. We have long lost the digestive system structure and enzymes necessary for breaking down large quantities of plant matter. Instead, our stomachs have the high hydrochloric acid (HCl) levels common to carnivores—our stomach pH ranges from 1.5 to 2.0, which is nearly the same as the 1.0 to 2.0 of a Wolf. HCl is necessary for the digestion of protein and kills harmful bacteria.

On the other hand, Chimpanzees, our closest primate relatives, have retained the plant matter digestive system features of our common ancestor. Chimpanzees have a non-acid stomach environment, with a pH hovering around 7, which is neutral. Not surprisingly, then, we find the Chimpanzee diet to be 97% plant matter.

The same is true for all other primates most closely related to Chimpanzees. Gorillas have a stomach pH that ranges between 5 and 7, with plants comprising 98% of their diet. The Gibbon’s diet weighs in at 94-97% plant matter, and the Orangutan’s percentage is similar.

Baboons, who are primates more distantly related to us and the other primates mentioned, have a stomach pH of 3.7, which is slightly acid and indicates a more significant animal component in their diet than in the diets of the primates we have covered. Sure enough, 20% of the Baboon diet is comprised of insects and small animals, with 80% being vegetable matter.

And so goes one central chapter in our evolution: the story of how our intimate relationship with Wolf helped make us who we are today. Ancestral legends have long described our long-standing kinship with Wolf and how similar we are, and now modern science appears to be backing that up.

There is a saying that we are what we eat. Evolutionary history appears to be telling us that we are also how we eat. It is the hunt—how we get our meat—that drew us into relationship with Wolf and orchestrated our evolution into highly functional and intelligent social beings. Without Wolf, we would likely not have the amazing story just told, not to mention that we might still be short, small-brained gatherer-scavengers. How blessed we as a species are for the privilege of walking this life together with Wolf as sister and brother.