Neanderthals May Have Feated On The Larvae They Collected From Rotting Flesh

And they probably threw away most of the meat of the muscle mass.

Neanderthals may have had a secret ingredient in the kitchen that provided them with the fatty protein necessary for survival. Instead of eating lean game meat, our prehistoric sister line may have deliberately kept their kills until the rotting carcasses were infected with the larvae, which they then ate.

This predisposition to larvae explains why Neanderthal remains tend to show such a high stable ratio of nitrogen isotopes. As a rule, it is hyperpredators, such as lions or wolves, that sit at the top of the food web when it comes to the level of nitrogen accumulated during the consumption of prey, but researchers have constantly found that Neanderthals were on par with these meat-loving predators.

"Neanderthals are actually taller than carnivores, so they don't sit in a trophic position in which you think they will sit," said Dr. Melanie Beasley from Purdue University. "The explanation why they are higher than carnivores was hyper predatory, but we are primates, so we can't consume the levels of protein that a lion, a hyena or a wolf could consume, because we are not evolutionarily not designed to be just carnivores," she told IFLScience.

Indeed, people cannot consume more than 300 grams of lean protein per day without getting seriously ill. Doing this for more than a week or two can lead to protein poisoning or "rabbit fasting", which can only be avoided by supplementing our diet with fats and carbohydrates.

In a new study, Beasley and her colleagues sought to determine the source of nitrogen in the diet of Neanderthals, using ethnographic descriptions of modern and historical groups of hunter-gatherers as inspiration. For example, they found that when groups of northern latitudes, such as the Inuit, killed, they gave most of the meat of their muscle mass to their dogs, consuming only fat parts such as the brain, tongue and organs.

In addition, the authors of the study note that "ethnohistorical records contain countless examples of indigenous peoples regularly consuming rotten food for animals with larvae". Therefore, they wondered if it could provide a secret source of both fat and nitrogen, which made up the bulk of the Neanderthal diet.

"Lenten game meat is an incomplete protein - it doesn't look like the livestock we eat today, and it's fatty, meaty meat," Beasley said. "But the larvae turn this lean game meat by eating it so that they themselves become fat, so by eating fat larvae with this lean game meat, you get a more complete nutrient of this fat with this meat."

To test their hypothesis, the researchers analyzed the stable ratio of nitrogen isotopes on 389 larvae of three families of flies, which they collected from rotting flesh. The results showed that while the process of decay led to a slight increase in nitrogen levels in meat, the larvae themselves showed much higher nitrogen values than meat, with up to 43.2 percent found in some larvae.

Thus, the authors of the study suggest that, like hunter-gatherers in northern latitude, Neanderthals probably threw away most of the muscle meat of their prey, focusing only on fatty components. "But we are taking an important step forward, assuming that late Pleistocene hominins often ate these fat-rich tissues in a spoiled or rotten state along with their almost inevitable infection with live and dead larvae," they write.

"It was the larvae, to a greater extent than the carcass tissues themselves, that gave the hominins of the late Pleistocene both a rich source of fat and a very [nitrogen-rich] source of protein."

In addition to revealing the mystery of the unexpectedly high nitrogen values of Neanderthals, this find also sheds new light on the habits of extinct hominins to store food and the ability to plan in advance. "If you think of a group of Neanderthals hunting a large mammoth, this carcass will lie on the landscape and rot, which will attract flies to it," Beasley said.

"So they probably thought: "okay, cool, let's come back in about a week, scoop up all these masses of larvae and treat them deliciously." It's an easily collectible food resource," she said.