Neanderthals got most of their protein from a nauseating food source

Neanderthals may not have relied as heavily on meat in the diet as previously believed. Earlier studies, based on analysis of nitrogen isotope ratios in their bones, suggested a diet that was dominated by animal protein.

However, new interpretations indicate they may have followed a more balanced and varied omnivorous diet that included plants and a hitherto unexpected ingredient: maggots.

“Masses of maggots are these easily scoopable, collectible, nutrient-rich resource,” said Melanie Beasley at Purdue University, Indiana. These insects offered essential nutrients and were likely simple to harvest.

Understanding maggots – the basics

Maggots are the squirmy, legless larvae of flies – usually houseflies or blowflies. They hatch from eggs laid in decaying organic matter, like rotting food, animal carcasses, or even open wounds.

As gross as they seem, maggots serve a real purpose in nature.

They devour dead tissue and break down decomposing material, playing a key role in the circle of life. Without them, our environment would pile up with organic waste far quicker than you’d expect.

But maggots aren’t just trash cleaners. In medicine, doctors have used sterile maggots in a therapy called maggot debridement to clean out infected wounds.

These little creatures eat only dead tissue, leaving healthy cells untouched. It’s creepy, but effective. People may recoil at the sight of them, but maggots can be surprisingly helpful – both in hospitals and in the great outdoors.

A delicacy across cultures

Evidence shows that maggots have long been part of human diets in various cultures. Beasley explained that reindeer hunters still cultivate the maggots of particular fly species as a delicacy.

In Sardinia, a traditional cheese called casu martzu even contains live maggots and remains highly prized.

Ethnohistoric accounts suggest that Indigenous groups not only tolerated but actively sought out maggot-infested animal foods – often regarding them as a delicacy despite the overpowering smell.

High nitrogen, wrong conclusions

Nitrogen has two stable isotopes: nitrogen-14 and nitrogen-15. As organic matter moves up the food chain, the proportion of nitrogen-15 increases.

When scientists examined the isotope ratios in Neanderthal fossils, they discovered a very high ratio of nitrogen-15 – higher than the ratios found in apex predators like lions and hyenas.

“So there became this narrative that Neanderthals were these hypercarnivores, very focused on big game hunting,” explained Beasley.

But not all researchers accepted this conclusion – especially since prehistoric Homo sapiens had similar isotope levels, despite their varied diets.

Neanderthals required maggots

Humans cannot survive on lean meat alone. “It’s actually physically not possible,” said Beasley.

“If humans eat as much protein as hypercarnivores do over long periods, without consuming enough other nutrients, it can lead to protein poisoning – a debilitating, even lethal condition historically known as “rabbit starvation.”

High protein diets cause dangerous levels of toxic byproducts like ammonia, which make survival unsustainable without fats and carbohydrates.

Studies of Neanderthal dental calculus also revealed plant remains, supporting the theory that they consumed more than just meat. This raises questions about the cause of their unusually high nitrogen-15 levels.

Rot brought protein-rich maggots

Ethnographic evidence suggests that Neanderthals likely cached or stored animal foods for long periods, often in rock piles, pits, or aboveground structures.

Over time, these caches would rot and attract flies, leading to maggot infestations. This behavior explains both the presence of maggots and the nitrogen isotope anomalies.

In 2017, John Speth from the University of Michigan proposed that consuming rotting meat might explain the isotope enrichment.

Beasley tested this idea at the University of Tennessee’s “body farm,” where she also studied maggots feeding on decomposing remains.

Maggots raised nitrogen levels

Together with Speth and Julie Lesnik at Wayne State University, Beasley found that while rotting meat showed only modest nitrogen-15 increases, the maggots that fed on that meat showed extremely high enrichment.

Their values often exceeded two trophic levels above typical herbivores, reaching as high as 43.2 percent.

“These are just initial results, but they show that eating a diet very high in meat isn’t the only possible explanation for the isotope ratios in Neanderthals and ancient Homo sapiens,” said Beasley.

She believes their diets likely combined multiple factors: meat storage, processing, cooking, and maggot consumption.

Maggots helped stretch Neanderthal resources

The study also highlights that Neanderthals, like other hunter-gatherers, could not sustain high protein intake. They would have deliberately targeted fatty prey parts like tongues, marrow, entrails, and organs, often discarding lean muscle.

Maggots, rich in both protein and fat, would have been a valuable dietary supplement for Neanderthals, especially during resource-scarce seasons.

“This is an exciting new study, and I think it goes a long way toward making sense of the strange results that have come out of isotope studies in Neanderthals and other Stone Age hominins over the last couple of decades,” said Herman Pontzer of Duke University in North Carolina.

“I find the evidence here pretty convincing, that consumption of maggots and similar larvae explains the ‘hypercarnivore’ signal we’ve been seeing in previous fossil isotope work.”

The findings suggest that those following a so-called paleo diet may need to reconsider their choices.

“All the people who want to go true ‘palaeo,’ they need to start thinking about fermenting their meat and letting the flies access them,” suggested Beasley.

Neanderthals’ complex food system

This research reframes how we view Neanderthal diets. High nitrogen-15 levels do not necessarily mean they were strict carnivores.

Instead, their eating habits likely involved a mix of fatty animal parts, plants, rotting meat and maggots from stored and decomposing food.

This complex food system reflects both survival needs and cultural practices shaped by unpredictable hunting returns.

The study is published in the journal Science Advances.

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