Rotten but Nutritious: Fermented Meat in the Paleolithic

The Raw and the Rotten (8)

This Post is a tribute to John D. Speth, Professor of Anthropology, University of Michigan. His landmark 2017 paper represented a significant course change for thinking about Paleolithic diets https://doi.org/10.1016/j.qeh.2024.100004. (See also [PDF] paleoanthropology.org)

Many varieties of fermented animal flesh are available today, throughout the world. Is this a recent development? Modern foragers suggest otherwise. There are also reasons to believe that our ancestors were consuming fermented meat for as long as they were eating meat.

For Pleistocene foragers, there were two primary benefits of meat fermentation: predigestion and preservation. Consider first predigestion, which chiefly effects animal proteins. Most animal proteins are extremely hard to digest in the raw state. Cooking is one way to predigest these proteins and render the constituent nutrients—peptides and amino acids--easier to assimilate. Before cooking, the consensus is that our ancestors had to rely on smashing and mashing, not nearly as efficient for predigesting proteins. (At best it removes some of the workload borne by teeth.) Fermentation, however, is potentially an even more effective way to predigest protein than cooking, as the Yakut encountered by Melville well knew. Recall that the fermented caribou meat Melville was offered “verily melted in my mouth”. It was predigested to a degree never attained by cooking alone.

The preservational function of fermentation is especially important for animal fats. Upon death, animal fats undergo a process called autoxidation, because of which they become rancid. The Polyunsaturated fatty acids (PUFAs), which are of particular nutritive significance, are the first fats to autoxidize and degrade into a rancid state. (I will explain what it means for a fat to be unsaturated in a later post, where I deal with fats more systematically). Lactic acid bacteria preserve PUFAs by producing antioxidants that slow autoxidation. Since autoxidation eventually contaminates the proteins, these antioxidants help preserve the proteins as well.

Fermented Meat in the Pleistocene

In 2017 (see above), John D. Speth argued that fermented meat, from fish to mammal, was an important source of nutrition for both Neanderthals and Modern Humans during the Pleistocene. This ran counter to the prevailing view in Darwinian Medicine, according to which, humans, uniquely among consumer of animal flesh, evolved an innate aversion for rotten flesh.

Speth noted many examples in which modern foragers seem to have lost this instinct, as I discussed previously. That’s not surprising because a lot of rotten flesh is rotten in a good way, however difficult that is to appreciate for Westerners for whom gastronomic squeamishness is culturally inculcated. There is no reason to believe our distant ancestors were similarly encultured. If they were, they probably wouldn’t be our ancestors.

Before we were hunters, we were scavengers. And once we became proficient hunters, we continued our scavenging ways, as do all predators. In the popular imagination, lions are considered predators and hyenas, scavengers. But hyenas hunt as much as lions and lions habitually scavenge, including hyena kills.

Recall, from a previous post in this series (The Raw and the Cooked. And the Rotten ) that there are two forms of scavenging with different implication regarding flesh freshness. In active, or aggressive scavenging, such as that reciprocally engaged in by lions and hyenas, those who make the kill are driven off by usurpers relatively quickly. To the victors go the quite fresh spoils. In contrast, passive scavenging is simply dining on found carcasses in varying states of rot. During the early Pleistocene our ancestors were not equipped to drive off predators for which they too were on the menu. Chucking stones at a sabertoothed cat is not a good idea no matter how coordinated the effort. So whatever large mammal meat they obtained was from passive scavenging, much of which was probably none too fresh.

In the Nilgiri Hills of Southern India both forms of scavenging occur. The Toda people routinely exploit Asiatic wild dogs (dholes) in their aggressive scavenging. Rather than hunt for themselves, they follow the dholes until they make a kill, then scare them off. This is the pinnacle of aggressive scavenging. The Kota people, with whom the Toda interact, do not practice aggressive scavenging nearly as much. Instead, they rely on rotten flesh for much of their meat, to the disgust of the Toda, and at least one European observer in the late nineteenth century, William Ross King: “They are also unclean feeders, devouring dead cattle, putrid flesh, birds of prey or vermin with as much apparent relish as fresh buffalo meat”.(The Aboriginal Tribes of the Nilgiri Hills, p.34. 1870).

Today, the Hadza of Tanzania practice both strategies. They often use vultures to guide them to carcasses. If the Hadza arrive when the lions or hyenas are still around, the meat is usually quite fresh but hazardous to obtain. Lions are much harder to intimidate than dholes. When only jackals and vultures remain on the scene the Hadza can secure the still fresh meat safely. But the Hadza are not averse to foraging rotting maggoty meat as well.

Eighteenth and nineteenth century European observers were disgusted by indigenous Australians who routinely consume rotten animal flesh, maggots and all. In fact, the maggots—fly larvae—were part of the attraction, a protein bonus. The same attitude toward maggots was true of indigenous Americans. This was considered proof, if any more was needed, of the savagery and inherent inferiority of the indigenous peoples, and their desperate need of European civilization.

There are countless other examples that refute Darwinian Medicine’s so-called Behavioral Immunity System. If such existed foragers would never have acquired a taste for maggots. Rotten meat, however, can be more iffy than rotten plant material and not just due to rancid fats. There are some nasty microbes that exploit rotten meat, none more so than the bacterium, Clostridium botulinum, the source of botulism. So Pleistocene foragers would want to avoid signs of Clostridium. It is noteworthy that among contemporary Arctic Peoples who routinely consume very rotten flesh, botulism was virtually unknown until quite recently, when “sterile” Western storage practices were introduced. Clearly, the traditional methods of preservation by acidic fermentation were superior. Some LAB deter C. botulinum by means of chemicals, called bacteriocins, that specifically target C. botulinum; other bacteriocins target Salmonella, another bad actor. Bacteriocins are bacterial anti-bacterials.

How could a forager determine if a rotting carcass was safe to eat, whether it was a good rotten or a bad rotten? Put that way, the question just posed is too simplistic. Much that is rotten is neither fermented to a high degree—what I have called the good rotten—nor spoiled, that is, toxic. Food in this broad middle ground is full of what I will call neutral rotters that speed decomposition (shorten shelf-life) but are not pathogenic. Food full of neutral rotters is still safe to eat, as Freegans (AKA dumpster divers) recognize. Most carrion falls into this category.

While repulsive for most Westerners, the odor, discoloration, and presence of maggots does not indicate pathogenicity. In fact, the presence of maggots is a good sign. Clostridium botulinum is also bad for maggots. Even the presence of some C. botulinum is not, in and of itself, necessarily a problem. Dosage is everything, which is why Botox (botulinum toxin) is such a popular treatment for those dissatisfied with their faces. As long as fermentative and other non-pathogenic microbes are predominant and pathogenic microbes remain at low levels, the highly acidic human stomach can usually handle things.

The Message from Lyuba

Any carcass begins to rot immediately after death. The progression of the rot is predictable in broad outline but varies in the details depending on environmental conditions. The rotting of mammal carcasses is especially well studied because of the inherent interest in human decomposition for forensic science. The first bacteria to act after death come from within the corpse, including the microbiome. If undisturbed by vertebrate scavengers, their activity will produce gasses that bloat the carcass. Eventually the pressure will explosively breach the skin, most famously of dead whales that occasionally wash up on beaches.

For large mammal carrion, scavengers do the degassing with their teeth. Once the internal bits are exposed, aerobic bacteria, mostly neutral rotters go to work. Next come the insects, especially flies, which deposit their eggs, soon to become the larvae that we call maggots. The aerobic bacteria soon deplete the flesh of oxygen, creating conditions suitable for fermentative bacteria such as LAB. The LAB create increasingly acidic conditions unsuitable for the aerobic bacteria, including most—but not all—pathogens. For the more anaerobic and acid-tolerant pathogens, such as C. botulinum, there are those bacteriocins.

The power of acidic fermentation is evident in Lyuba, a baby wooly mammoth that died 41,800 years ago. She was recovered in the Russian arctic in 2006, almost completely intact https://doi.org/10.1016/j.quaint.2011.05.040. (Dogs had nibbled at her ears and tail.) Lyuba’s state of preservation was remarkable; all her tissues--fat, muscle, blood, lungs, skin, hair and cartilage, among many others, could be easily identified as such. We even know what plants she consumed for her last meal. In part, her state of preservation can be explained by the frozen environment in which she was found. But Lyuba didn’t die in a frozen environment; it was a grassland at the time. She seems to have drowned in a pond, where her rotting began. Furthermore, it is estimated that her carcass had been exposed to temperatures far above freezing for up to a year prior to her discovery. So, the cold environment alone could not explain her preservation.  Rather, Lyuba was fermented. Her tissues were full of lactic acid and as a result her carcass gave off a sour—not rancid—smell.  In principle, Lyuba could have been eaten when discovered without ill effect.

Neanderthals routinely hunted and scavenged mammoths. Like all Pleistocene foragers, Neanderthals ate virtually every part of the carcass. As such, a single mammoth would provide tons of meat and fat from muscles to internal organs. Given a typical Neanderthal group size of a few dozen individuals, most of the animal could not be consumed in a “fresh” state. By the end of month, the mammoth flesh would have been well along the path of fermentation. Modern Humans also hunted mammoths and therefore could have consumed similarly fermented meat. It is likely that both Neanderthals and Modern Humans cached much of the flesh as Arctic foragers do today. This practice facilitates fermentation and hence preservation.

Another Message from Lyuba

Lyuba drowned in a pond. The pond environment was an important factor in her preservation. Pond water is low in oxygen, and therefore slows autoxidation. The low oxygen environment provided by pond water also favors anaerobic bacteria like LAB; aerobic spoilage and neutral rotter bacteria struggle in this environment, no matter the temperature.

With this background we can better understand the otherwise surprising results of experiments conducted by Daniel Fisher, a Paleontologist at the University of Michigan. Fisher was part of the Lyuba study, and much of his research concerned Mammoths and Mastodons, and their human predators. He strongly suspected that humans deliberately cached mammoth remains in ponds and bogs for preservation by way of fermentation, much as Lyuba had inadvertently been http://hdl.handle.net/10900/114208). For an initial test of this idea, Fisher placed butchered units of a 1,500 lb. draft horse into a pond during the winter; he cut holes in the ice and anchored the various horse parts to the bottom, then checked their state of decay in the succeeding months. There was little change in the “meat freshness or bacterial load over the course of the winter. But come spring, the pond carcass pieces came to acquire the sour cheesy smell characteristic of lactic acid fermentation. In early June algae began to proliferate on the outer surfaces creating an unappetizing appearance. But the meat and fat tissue remained quite edible and pathogen free. The flesh, though disintegrating, remained safe to eat in August, during a typical hot and humid Michigan summer.

Carcass disintegration is undesirable because of the loss of potential calories. Fisher found much less disintegration in the butchered parts he placed in bogs. Underground storage, or burial, also reduces oxygen availability and tilts the scales toward fermentation and hence preservation. Even highly nomadic Pleistocene humans could easily cache fermenting flesh for later visits much like historical Arctic foragers. And as the Michigan experiments demonstrate water storage can also be effective in warm environments.  African hyenas often store surplus meat in shallow water.

What about scavenged animal flesh? Of the foraging peoples remaining in Africa, the Hadza dwell in an environment closest to the ancestral one for Archaic and Modern Humans. They consume rotten flesh routinely to no ill effect. Europeans who first encountered Native Americans from the northeastern woodlands remarked on their exploitation of rotting deer carcasses happened upon. Along the gulf coast, dead fish were routinely scavenged.

When it comes to scavenging, beached whales provide by far the greatest bounty. Today, off the California coast, when dead whales wash up, the complaints about the “intolerable” odor are quick to follow. The whales are usually towed out to sea. Lest they return to shore in an even “riper” state, the carcasses are filled with explosives and detonated into tiny bits of rotten flesh, which all manner of fish, birds and marine mammals are quick to consume.

Traditional coastal foragers would weep at this waste and not only in the Arctic.  Coastal foragers from Spain to South Africa and Australia were known to exploit rotting whale carcasses with gusto, a true boon. As is to be expected, European observers were disgusted. Here’s a quote from one ship captain who witnessed a dead whale harvest at Manly Cove in  New South Wales, Australia: On drawing near the shore, a dead whale,, in the most disgusting state of putrefaction, was seen lying on the beach, and at least two hundred Indians surrounding it, broiling the flesh on different fires, and feasting on it with the most extravagant marks of greediness and rapture” (Tench, 1793; from Cawthorn 1997).Another failure of the non-European disgust response.

Evidence That Pleistocene Foragers Consumed Fermented Flesh

Direct evidence of deliberate fermentation is inherently difficult to acquire. Fortunately, a few have begun looking for signs of intentional fermentation among prehistoric foragers. Adam Boethius (2016) found compelling evidence for deliberate fish fermentation in southern Sweden dating back 9,200 years, at least 6,000 years before agriculture reached the area 10.1016/j.jas.2016.01.008. Rock structures were built by foragers for the sole purpose of fermenting freshwater fish. Surstromming, it seems, has an ancient pedigree. More generally, a number of the fermented fish products described in the first chapter probably reflect traditions dating back to the foraging societies that formerly occupied those areas. Speth collected ample evidence of diverse forms of fermented fishes from the historical record provided by explorers of the then much more plentiful foraging societies. For northern societies that continue to lead a foraging or semi-foraging existence, fermented fishes—including stinkhead—remain an important part of their diet, despite strenuous discouragement from their Western overseers.

Modern foraging and semi-foraging peoples of the Arctic--including the Yupik, Inuit, Inupiak and Inuvialiut-- are acclaimed by Paleos as examples of how to stay healthy on animal flesh alone. Quaak—a raw fish that has been frozen then half thawed-- is particularly celebrated by those Paleos who are also part of the raw food movement. This is a food that should not trigger the Western disgust response. Much less is made of traditional fermented foods consumed by the same peoples, such as stinkhead, fermented seal flipper and kiviak, which obviously do elicit strong disgust in most Europeans, including practitioners of the Paleo Diet.

But one such practitioner, at least, has broken through the Western disgust barrier. His name is Derek Nance and he subsisted for years on what is widely reported to be raw meat. But that is stretch the meaning of both “raw” and “meat” beyond anything that any European would recognize. Let’s start with the “meat”. Derek consumes every part of the animal, internal organs, brains, stomachs and their contents, and back fat included. In this he has very much adopted the eating habits of a true forager, to a degree that far exceeds that of Paleo Diet advocates. What about the “raw” in his diet, which I have argued is not sustainable for humans? He certainly doesn’t cook, but it turns out he eats a lot of really rotten flesh. (Here too he is more Paleo than other Paleos.) This rotten flesh, though uncooked, is pre-digested by fermentative microbes. And it is Quite nutritious.