These Ancient Hunter-Gatherers Went Ham on Plants

Some hunter-gatherer societies, like in the Andes, were thought to subsist heavily on meat. Turns out, that wasn’t the case.

Abundance of organic and starchy potatoes, roots of plant, belonging to family Solanaceae, lying on ...
Iuliia Burmistrova/Moment/Getty Images

The carnivore or all-meat diet is often heralded as a return to our ancestral roots. It somehow taps into the clean bill of health supposedly enjoyed by our hunter-gatherer ancestors. While the benefits of continuously dining on roasted beef tenderloin are debatable (more likely, not good for you), it turns out ancient humans, at least in some parts of the world, probably preferred a plateful of veggies.

In a study published Wednesday in the journal PLoS One, a group of researchers led by the University of Wyoming found for early humans living 9,000 to 6,500 years ago on the Andes Altiplano (a high-altitude plateau in the Andes Mountains), their diet was about 80 percent plant-based, on average, and only 20 percent meat-based. This finding was based on an isotopic analysis of the remains of 24 individuals excavated from two ancient burial sites in Peru, a process where the levels of carbon and nitrogen found in food were assessed from bone.

“This study shows that at least some early human communities did not have meat-based diets,” Randy Haas, an assistant professor of archaeology at the University of Wyoming who led the study, tells Inverse. “I’m fairly confident when people perform this kind of isotopic analysis elsewhere in the world, they will find that meat tends to be overestimated in the reconstruction of early human diets.”

A biased record

The idea that early humans subsisted on meat isn’t entirely unwarranted. In terms of the economics of diet choice, says Haas, if there are plenty of animals to hunt and not much competition with other humans, meat provides an economically profitable source of calories per unit of effort. Theoretically, this economy would gradually shift, as it has among contemporary foraging communities, towards incorporating more plants as human populations grew and became more sedentary and various animal populations declined.

“When we look at the archaeological record of early human economies, what we see are lots of projectile points, like stone spear points and stone atlatl points, that are unequivocally associated with hunting,” says Haas. (An atlatl is an ancient hunting tool similar to a spear.) “We also see a lot of animal bone in archaeological assemblage, and this is true in the region where I work in the high Andes.”

But herein lies a problem: Just because we find lines of evidence pointing to the strong possibility of hunting and meat consumption among early humans doesn’t mean that’s the entire picture.

“The archaeological record is biased towards the preservation of hunting artifacts. Stone tools stick around for archaeologists to observe. Bone preserves reasonably well in the archaeological record. Plant foods and the perishable tools that are used to harvest them generally don’t last for archaeologists to observe,” says Haas. “So we’ve been dealing with this biased record all along.”

Tubers for the win

In the new study, Haas and his colleagues wanted to intimately examine the chemical composition of ancient Andean bone using a technique called isotopic analysis that’s been used by archaeologists to determine things like population movements and diet from elements lingering in ancient human remains.

The researchers analyzed for stable isotopes — atoms with extra or missing neutrons — of two elements: carbon and nitrogen. Plants absorb carbon through their environment and generate some during photosynthesis. When we eat plants, our bodies take up whatever stable isotopes of carbon are present in our tissues, including bone. On the other hand, nitrogen correlates with eating meat, with the ratio of stable nitrogen isotopes telling us how high an animal was on the food chain (like whether it was a plant eater itself or a carnivorous predator like a cave lion).

The Wilamaya Patjxa archeological site in Peru produced human remains showing that the diets of early people of the Andes were primarily composed of plant materials.

Randy Haas / University of Wyoming

Haas has been excavating two ancient burial sites in Peru since 2013. The two sites, located in close proximity to each other up in the Andes, revealed the remains of 28 humans — 16 from Soro Mik’aya Patjxa and 12 from Wilamaya Patjxa. (These individuals all dated back as far as 9,000 to 6,5000 years ago.) Haas and his colleagues ended up performing isotopic analysis on bones from 24 individuals and also analyzed little bits of plant matter discovered at the sites.

The researchers were expecting the stable isotope levels for nitrogen compared to carbon to be high since it was assumed these ancient Andeans were meat eaters. Instead, they were surprised to find the exact opposite: Plants dominated the diet anywhere from 70 percent to 95 percent, with 80 percent on average.

Drilling deeper, the stable isotopes for carbon seemed characteristic of those found in tubers, aka potatoes. This was corroborated by the little fragments of plant matter Haas and his colleagues discovered, which turned out to be wild potatoes.

“There’s pretty good reason to think that of the plants being consumed, tubers were probably the most prominent because that’s what we see in the paleoethnobotanical record,” says Haas. “That jives pretty well with some other lines of evidence that this is the part of the world where we think potatoes were domesticated. This [all] would seem to suggest that the relationship with wild potatoes probably started much earlier than we previously thought in this part of the world.”

The search for ancient plant eaters elsewhere

While it's tempting to take these findings as a clarion call, reevaluating our perceptions of ancient diets, Haas advises caution before extrapolating what the ancient Andeans ate to other parts of the world.

“I wouldn’t say that, for example, just because we’re observing 80 percent plant diet in the high Andes 9,000 years ago, that necessarily means that other early human populations did the same thing,” he says. “I think what it does show pretty definitively is that there’s at a minimum more diversity in early human diets than we previously thought.”

Haas and his colleagues hope their research is an invitation to others to consider diversity within ancient diets around the world and perhaps further investigations into the potential implications of plant-based ancestral diets on contemporary health.

So the next time you catch yourself drooling over an In-N-Out double-double, maybe include a hefty portion of veggies on the side. Your ancestors will thank you.

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