Neanderthals probably ate something most of us would find hard to swallow—meat that was left to rot, ferment, and fill up with maggots. According to a new study, this unappetizing menu choice could solve a long-standing mystery about our Ice Age cousins—one that had scientists scratching their heads for decades. 

It turns out that the secret to Neanderthal survival in harsh environments may not have been how much meat they ate, but how they prepared and stored it. In fact, fat and protein-rich maggots might have played a crucial role in keeping them alive and well-fed.

This fresh take on Neanderthal eating habits suggests they were savvy survivors who knew how to make the most of every animal they killed—preserving meat through natural fermentation, tolerating the stink, and even relishing the maggots that came with it.

The Neanderthal diet is confusing, but why?

For years, chemical tests on Neanderthal bones revealed something unexpected. They had extremely high levels of a rare form of nitrogen, one that usually shows up in top predators like lions or wolves. This suggests Neanderthals were eating enormous amounts of meat, more than most modern humans could handle. But this didn’t make sense.

Humans, including Neanderthals, aren’t built to survive on a pure meat diet for long. Too much lean protein, without enough fat or carbohydrates, can lead to a dangerous condition called protein poisoning (rabbit starvation), which causes nausea, fatigue, and eventually death. So if Neanderthals were eating like apex carnivores, why weren’t they dying from it?

“Normal daily protein intakes of the large predators, if consumed by hominins on a sustained basis, would be toxic, even lethal.” 

This is where the new study comes in with an interesting explanation. Instead of focusing only on what Neanderthals hunted, researchers asked a new question. What if the condition of the meat mattered more than the amount?

To test this idea, the scientists looked at maggots. These fly larvae appear naturally on meat that’s left to decompose, and they’re a surprisingly rich source of fat and nutrients. In many traditional Arctic societies, where fresh food is hard to preserve, people have long eaten fermented or semi-rotten meat, and even considered maggots a delicacy. 

But how could anyone choke down rotting meat and maggots when the stench alone could knock you out? Well, according to experts who have studied ancient societies, the disgust triggered by the smell, sight, or taste of rotting meat and maggots isn’t something all humans naturally have. It’s mostly learned. 

For instance, in many traditional and indigenous cultures, especially before industrialization and urban living, people regularly ate putrid meat and didn’t find the smell unbearable. What’s more, they could eat it safely because early exposure to microbes in their environment helped their immune systems and gut bacteria handle harmful pathogens.

“While our Western sensibilities might abhor the thought of maggot-infested foods, indigenous peoples almost universally viewed thoroughly putrefied, maggot-infested animal foods as highly desirable fare,” the study authors note.

Did Neanderthals develop similar dietary habits?

To find out, the researchers used data originally collected for forensic science. At a facility in Tennessee that studies human decomposition, scientists had measured the nitrogen isotope levels in muscle tissue as it broke down, and in the maggots feeding on it.

When the researchers reanalyzed this data with prehistoric diets in mind, they made a striking discovery. As muscle decomposes, its nitrogen-15 (¹⁵N) values increase slightly, rising from about -0.6 to 7.7 per mil. 

However, when it came to the maggots feeding on that tissue, their nitrogen values reached as high as 43.2 permil. That’s far beyond the normal range for Ice Age herbivores (0.9–11.2 permil), and even higher than what’s found in most predators.

This means that if Neanderthals regularly ate rotting meat containing high-fat maggots and fermented tissues, the nitrogen values in their bones would look almost identical to those of pure meat-eaters. However, in reality, they were likely getting a more balanced and fat-rich diet, without the risks of protein overload.

“We suspect the high δ¹⁵N values seen in Neanderthals reflect routine consumption of fatty animal tissues and fermented stomach contents, much of it in a semi-putrid or putrid state, together with the inevitable bonus of both living and dead ¹⁵N-enriched maggots,” the study authors said.

A new view of ancient appetite

This study rewrites part of the Neanderthal story. Their high nitrogen signatures, long assumed to reflect extreme carnivorous behavior, now hint towards a clever adaptation. By feeding on rotten meat and maggots, Neanderthals not only maintained a high-protein balanced diet, but also avoided nutritional pitfalls like protein poisoning. 

However, maggots alone may not be the complete answer. Researchers still don’t know how much larvae would need to be consumed to meaningfully shift ¹⁵N values, or how different storage and cooking methods alter the nutritional profile of decomposing foods. 

Future studies, including experiments based on Indigenous food processing techniques, could offer more insights. However, one thing is clear: Neanderthals weren’t just meatheads, they were experimental eaters with a tolerance for the funky, the fermented, and the fattened-up fly. 

The study is published in the journal Science Advances.