500-300 BCE

GUT SCENT – The Smell of Guts

Victor Golubev & Sean Coughlin

Institute of Philosophy, Czech Academy of Sciences

εἰ πάντα τὰ ὄντα καπνός γένοιτο, ῥῖνες ἂν διαγνοῖειν

If all existing things became smoke, the nose would discern them.

Heraclitus Fragment 7 DK (reported in Aristotle, On sense and sensible objects 5, 443a24-25)

INTRODUCTION

Scent was a prominent part of the experience of ritual animal sacrifice in Greco-Roman antiquity. Literary sources of the period typically describe the experience as pleasant, focusing on the scent of the animal meat roasting on the altar fire. This scent, called knisa in Greek and nidor in Latin, is one of the primary purposes of the ritual, being not only pleasant in itself but also the offering presented to divine beings (as in Homer):

οἳ δ' ἀπελυμαίνοντο καὶ εἰς ἅλα λύματα βάλλον, ἕρδον δ' Ἀπόλλωνι τεληέσσας ἑκατόμβας ταύρων ἠδ' αἰγῶν παρὰ θῖν' ἁλὸς ἀτρυγέτοιο· κνίση δ' οὐρανὸν ἷκεν ἑλισσομένη περὶ καπνῷ.

They cleansed themselves and threw the dirt into the sea. Then they offered a perfect sacrifice of bulls and goats near the shore of the barren sea. And the knisa (the scent of fat and meat) reached heaven, whirling within the smoke.

Homer, Iliad I 314-317 (tr. Coughlin)

Animal sacrifice, however, would have produced conditions for a far more complex smellscape than the hedonic and performative one emphasised in literary sources. Entrails of freshly slaughtered animals would have released odorant compounds typically characterised today as foul, acrid or otherwise unpleasant (fig. 1). Concentrations of such compounds would vary during the ritual, with some present during the slaughter and butchering of the animals, others during the removal and roasting of the inner organs. Literary sources rarely discuss scents beyond roasted meat. This may be because they were not part of the focus of the ritual, or precisely because they were unpleasant. Nevertheless, we can use literary, epigraphical and iconographic sources and organic chemistry and biochemistry to reconstruct what compounds would have been present at the different stages of the animal sacrifice. Within these stages, the entrails of the sacrificial victim—organs like the heart, liver, spleen, gallbladder, kidneys and large and small intestines—would have contributed unique chemical compounds to the environment that would be detectable by participants and their noses. The experience and interpretation of these compounds vary with social, cultural, individual and biological factors. The compounds themselves however are stable reference points for understanding how entrails were or may have been experienced during ritual sacrifice.

THE SMELL OF GUTS

Odorants of animal slaughter

In the first stage of animal sacrifice, the animal, often a goat, sheep or bull, but also sometimes swine, is brought to the altar. Its throat is slit and the animal is bled (fig. 2). Some of its blood is poured onto the altar as an offering (as described by Homer):

αὐτὰρ ἐπεί ῥ' εὔξαντο καὶ ἔσφαξαν καὶ ἔδειραν, μηρούς τ' ἐξέταμον κατά τε κνίσῃ ἐκάλυψαν, δίπτυχα ποιήσαντες, ἐπ' αὐτῶν δ' ὠμοθέτησαν. οὐδ' εἶχον μέθυ λεῖψαι ἐπ' αἰθομένοισ' ἱεροῖσιν, ἀλλ' ὕδατι σπένδοντες ἐπώπτων ἔγκατα πάντα.

Now after they prayed, slaughtered the animals, and skinned them, they cut out the thigh-pieces and covered them with knisa (here the fat and meat themselves), having prepared and placed a double layer of fat and meat onto them. They had no wine to pour over the blazing sacrificial fire, but they made libations with water and roasted in addition all the entrails.

Homer, Odyssey XII 359-363 (tr. Coughlin)

When oxygen comes into contact with blood cells, they will start to necrotize (undergo cell death), causing them to release their contents into the environment. Red blood cells are highly sensitive to oxygen and can begin to undergo hemolysis (breakdown) within minutes of coming into contact with it. The blood would smell metallic and slightly sweet, primarily due to iron-containing compounds such as haemoglobin. Haemoglobin, present in red blood cells, is responsible for transporting oxygen and gives blood its distinctive red colour. When blood is exposed to air, the iron in haemoglobin reacts with oxygen to form iron oxide, which can oxidatively interact with lipids (fats) to form volatile aldehydes and ketones, which are the source of the characteristic metallic smell (fig. 4a). In addition to haemoglobin, other compounds present in the blood can contribute to its odour profile, such as urea and other nitrogen-containing compounds, amino acids, and lipids. Volatile compounds are also present in animal blood and these can contribute to its scent. They include indole (musty, floral odour), skatole faeces-like odour, (fig. 4b), and trimethylamine (ammonia or “fishy” odour), which are produced by bacteria in the gut. They also include alcohols, aldehydes and ketones, which are produced as a result of metabolic processes in the body. The scent of blood can also vary depending on other factors, including the animal species, its age, and the kinds of bacteria or other microorganisms in the animal or environment.

Odorants during butchering and removal of entrails

After the blood is removed from the animal, it is either suspended vertically or laid horizontally, then cut along the length of its belly. At this point, its entrails (entera, enkata) are removed. First the viscera (splanchna), likely including the heart, liver, pancreas, and spleen are removed. These are followed by the large intestine (koilia) and other organs, providing access to the kidneys (nephron). Finally, the small intestine (skolion) is removed and discarded or more likely cleaned and used as sausage casing. When the abdomen is opened, the release of bodily fluids and gases would be accompanied by compounds typically characterised as having a strong and unpleasant odour. These include skatole and indole which we have already encountered, but also ammonia (characterised by a strong, pungent odour, often described as acrid, fig. 4c), and so-called “ptomaines,” including putrescine (rancid odour, one of the main contributors to the odour of rotten meat, fig. 4d) and cadaverine (another compound responsible for the odour of decaying meat, fig. 4e). Skatole and indole are produced by the bacteria in the intestines during the breakdown of amino acids (fig. 4b). Ammonia is formed from urea in the presence of urease, commonly present in bacteria (fig. 4c). Putrescine and cadaverine are produced from the breakdown of amino acids by bacteria, particularly in rotting or decaying animal tissue (fig. 4d & e). Due to the presence of bacteria in the intestines, these compounds could also be formed in living animals and be released after dissection. In addition, mercaptans, a group of sulphur-containing compounds with a strong unpleasant smell, can result from the breakdown of animal tissues as well in the process of digestion. The odour may be more intense in warmer and more humid environments, as these conditions can accelerate the decomposition process and increase the release of odour-causing compounds. According to some modern studies, the raw meat of freshly slaughtered beef can contain a large variety of volatiles, often weak and somewhat sweet smelling: limonene (citrus-like), 2-Methyl-3-buten-1-ol (floral odour), acetoin (sweet, buttery odour), 6-Methyl-3-buten-1-ol (grassy odour), nonanal (fatty soapy odour), acetic acid (vinegar-like odour), γ-Butyrolactone (sweet, creamy odour), 1-Nonanol (sweet, fatty odour). Acetic acid, butyrolactone and nonanal are present in greatest proportions, however, the exact perception of the smell will depend on personal sensitivity. It should be noted that the conditions of modern studies will not correlate precisely with the historical context of animal sacrifice. In addition to cultural, social and individual differences in the perceivers, variation in animal diet, hygiene and health would likely also result in perceived differences, with faecal odours having been reported in the case of disorders of the liver, and putrid and ammonia-like odours reported in the case of abscess and peritonitis.

Odorants of roasting entrails

Along with some other parts of the animal, the entrails were often perquisites (reserved items) of the priest. In iconographic sources, the priest first roasts what is called the “divine portion” (hiera moira) of the animal, usually identified with the osphus or tail-bone. After the divine portion is cooked, attendants holding the viscera (splanchna) on skewers or spits will place them into the ritual fire (fig. 3). After roasting, the viscera are then eaten. The odour of roasted organs is likely included as part of the knisa, the combination of smoke and the experience of smokey and meaty scents mentioned in literary sources. However, the chemical component of such a sensory experience would be complex, depending on, among other factors, the type of wood used as fuel, the state of the organs and the species of animal. We can examine in more detail the complex mixture of volatile compounds that would contribute to the unique profile of roasted viscera, including fatty acids, amino acids, sugars, and products of their thermal decomposition. Heat from the fire will cause fatty acids to be formed by the decomposition of fats and oils present in the viscera. Some of the major fatty acids that contribute to the odour of roasted sheep organs include octanoic acid (caprylic acid) and decanoic acid (capric acid). During roasting, amino acids can also be released by means of the denaturation of proteins in the organs, and these can have distinctive odours, like alanine (fruity or flowery odour) and glycine (caramel odour). Sugars as well as these amino acids can undergo further thermal degradation reactions that result in the formation of volatile compounds. Some of the major volatile compounds produced during the thermal degradation of glucose include 5-Hydroxymethylfurfural (HMF) and furfural (caramel, buttery odour, fig. 4f & g). Thermal degradation products of glycine include 2,5-Dimethylpyrazine (roast, nutty odour) and 2-Acetylpyridine (sweet, fatty odour, fig. 4h & i). These compounds will interact with each other to produce a complex scent mixture. Some literary and iconographic sources suggest entrails like intestines or the bladder may have been roasted at a late stage of the process (fig. 5), contributing other compounds we have encountered to the odour profile, including skatole, indole, ptomaines, and ammonia. The fire itself will also contribute to the overall odour by producing smoke and other compounds that interact with the smell of the roasting viscera. These include polycyclic aromatic hydrocarbons, volatile organic compounds, and benzene, which would contribute a smoky odour to roasted entrails.

Conclusions

The scent of guts would have been inescapable during ritual animal sacrifice. The viscera and entrails of animals would have contributed distinctive compounds to the chemical environment in the air around participants. Literary, epigraphic and iconographical sources allow us to reconstruct in more detail the way that environment would change during the ritual, starting from compounds associated with blood, to those released during removal of the entrails, to the degradation products produced when they are cooked. Without modern antibiotics, bacterial processes that contribute to odour-related compounds may have been more common in domesticated animals in the past and scents related to decay could also have progressed more quickly.

Ancient Greco-Roman literary sources offer few descriptions of how this changing chemical environment was experienced. They focus mostly on the odour of knisa, the scent of smoke and roast meat which was said to be pleasing to both human and divine beings. We can assume, however, that the scent of ancient guts would likewise have been experienced. How participants at these sacrifices would have described such experiences remains unclear.

Acknowledgments

Victor Golubev researched odorant compounds, provided the reconstructed sequence of compounds in the chemical environment, and wrote the body of the text. Sean Coughlin researched the literary and iconographic evidence for ancient Greco-Roman animal sacrifice, wrote the introduction and conclusion, selected images and edited the final draft. This paper is the result of research conducted at the Department of Ancient and Medieval Philosophy, Institute of Philosophy, Czech Academy of Sciences in Prague, as part of the project, “Alchemies of Scent,” funded by the Czech Science Foundation, GACR Grant ID 21-30494M.

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