New research has proposed an unconventional explanation for the unusually high nitrogen isotope levels found in the remains of Neanderthals: the routine consumption of maggot-laced, decomposing meat.
Researchers at Purdue University – published in Science Advances – used stable nitrogen isotope analysis (δ¹⁵N) to test whether eating fly larvae from putrefied animal foods could explain values previously attributed to extreme carnivory.
Neanderthal bones often show δ¹⁵N values that exceed even those of known top-level predators such as wolves and hyenas. Since δ¹⁵N is a standard indicator of an organism’s position in the food web, this has typically been interpreted to mean Neanderthals were hypercarnivores. However, some researchers have noted that human digestive systems are not well-equipped for an exclusively meat-based diet, raising doubts about whether such extreme carnivory would have been physiologically viable for Neanderthals.
To explore alternative explanations, the team analyzed muscle tissue from 34 human cadavers that had decomposed over two years at the University of Tennessee’s Forensic Anthropology Center. They measured δ¹⁵N in both the tissue and in 389 samples of fly larvae from three common carrion-feeding families: blow flies (Calliphoridae), cheese flies (Piophilidae), and black soldier flies (Stratiomyidae).
While decomposing tissue showed only modest nitrogen enrichment (up to 7.7 percent), the larvae were far more enriched, with δ¹⁵N values reaching 43.2 percent. For comparison, typical values are around 5 percent for herbivores and 9 percent for carnivores. Even when accounting for isotope shifts from tissue to bone, the larvae’s enrichment remained well above what would be expected from meat consumption alone.
“These high δ¹⁵N values observed in fly larvae raised on putrid tissue are particularly interesting when considering the elevated values repeatedly observed in Late Pleistocene hominins,” the authors write. They suggest that Neanderthals may have regularly consumed maggot-infested stored meat, a practice documented among numerous indigenous groups and supported by ethnohistoric records.
Though not conclusive, the study highlights a dietary behavior that could account for anomalous isotope signals in fossil remains – without requiring an unsustainable intake of lean meat. “We recognize the tentative nature of these conclusions and encourage further investigation,” the team noted.
The authors suggest future work should involve isotope and macronutrient analyses of maggots raised on a broader range of substrates, including animal species more representative of Paleolithic hunting. They also call for further experimental modeling to quantify the impact of maggot consumption on nitrogen isotope profiles.
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