Why did Prometheus' liver regenerate?

For giving fire to mortals, the titan Prometheus was chained on Mount Caucasus and condemned to have his liver completely devoured every day by an eagle or a vulture. To endure the torture, his liver had to regenerate. Although not in such an extraordinary way, the human liver also regenerates itself. Does this mean that the Greeks knew this mechanism? One might also ask, why was his liver attacking him?

Who is Prometheus?

In general, from Hesiod to Oppianus of Anazarbus, Prometheus was the son of the titan Jeapetus. In what there is not so much consensus is in the identity of his mother, who usually were the oceánides Clímene or Asia, but also his grandmother Gea or his aunt Temis. His siblings were Menetius, struck by Zeus' lightning and imprisoned in Tartarus; Atlas, who ended up condemned to endure the heavens, and Epimetheus, who instead condemned humanity by accepting Pandora's gift.

By his name, for the Greeks he represented foresight (Προμηθεύς, pro, "before" and metis, "intelligence"), in contrast to his impulsive brother Epimetheus. However, his name could be linked to the Sanskrit pra math, "to steal". Through this relationship, he would be connected to the Hindu Matariswan, name of the fire god Agni in the Rigveda or a being related to it. Alternatively, Hesychius of Alexandria called him Itax, considering him a herald of the Titans.

Summary

Although he helped the Olympian gods in the Titanomachy, he was the classic trickster god who transgresses the established norms, using his wit to test their limits. In Mecone, according to Hesiod's Theogony, he sacrificed a great ox. On the one hand, he hid the entrails, meat and fat in its belly, while he covered the bones with shiny fat to make them look appetizing. He then offered them to Zeus, but Zeus, knowing the deception, took the white fat from the bones. This was meant to explain why the gods were offered the bones in sacrifices if they were intended to curry favor with them, while humans consumed the meat.

As punishment for his insolence, he forbade the use of fire to men, so that they would have to eat the raw meat like animals, but when he saw that someone had given it to him, he sent the first woman, the creation of Hephaestus, to the land of mortals, bringing the golden age to an end. For his part, Prometheus would be chained to Mount Caucasus so that an eagle or vulture would daily devour his liver. As we are told in Prometheus unbound by Aeschylus, Hermes told him that Zeus will also cause the collapse of the mountaintop over him if he does not reveal who will be the one to overthrow him, but Prometheus does not agree. Finally, Heracles would kill the bird and free the titan, who would obtain immortality from Chiron, who renounced it to die, because an arrow of Heracles soaked in the poison of the hydra had hit him and caused him unbearable pain.

These events showed why Zeus hardened the life of humans, which in every age was more miserable. Additionally, it showed how the Chronid defeated on his own ground even the most intelligent of the Titans, so that rebelling was pointless. However, in Aeschylus' play, Zeus is a cruel and distrustful tyrant, acting through Cratos ("Power") and Bia ("Strength").

Functions

Based on this account, three related elements of this trickster god are understood: fire, animal sacrifice and the ability to foresee the future and act accordingly. This not only shows how humans can obtain divine favor by sacrifices, but also opened the door to the discipline of extispicy, which, through the inspection of organs, aimed to answer affirmatively or negatively about the destiny of men. In this discipline, the first thing that was performed was hepatoscopy, the observation of the liver, since it was believed that the gods resided in it.

Prometheus was involved beyond what was related by Hesiod and Aeschylus or the mentions of authors such as Pseudo-Apolodorus. In addition to the use of Prometheus by Aristophanes in The Birds or by Plato in Protagoras, it is known that, at least since the 5th century BC, he was considered the creator of mankind. A fable attributed to Aesop states that he created humans from mud and tears, a fact repeated with variations by the Greek comic poets Menander and Philemon and the Roman authors Ovid, Catullus, Horace and Propertius.

Dual inmortality

Immortality can be understood in several ways. In the simplest form, it implies eternal life, as long as there is no obstacle that makes it impossible, such as murder. To overcome this, there would be invulnerability, which would prevent any threat, but would be a problem if it came from the body itself. In the case of the Greek gods, their immortality is at another level, because having eternal life, they could be wounded, torn to pieces or subjected to other powers, but their existence remained. There are many examples of this: As children, the Olympian gods survived being devoured by their father; Typhon tore off Zeus' tendons but Zeus recovered when Hermes gave them back to him; Zeus swallowed his first wife Metis, begetting Athena in his head; the Titans dismembered Dionysus and devoured his pieces, but Athena recreated him through her heart. Likewise, the gods enjoyed eternal youth, unlike Titonus, whose immortality was granted by Zeus at the request of Eos, without her sparing him from aging. With this in mind, although it did not prevent his suffering, it is evident that Prometheus' immortality extended to his organs.

However, a problem arises here. Immortality and liver regeneration are a sine qua non for both enduring torture and extending it indefinitely. Despite this, he receives immortality from Chiron. Although the narratives of the story may vary in detail, Prometheus' immortality is obligatory, especially when it would take thirteen generations for Herakles to be born.

Both Chiron and Prometheus are characters distinguished by their intelligence and teaching who suffered from incurable pain from which they could not free themselves due to the privilege of immortality. Both are deprived of the pleasures of life and their pain is unbearable, unlike the wounds usually suffered by the gods. With his renunciation of immortality, Chiron takes Prometheus' place in the underworld, while the latter ascends to the heavens.

Importance of the liver

For the ancient Greeks, the liver had the same importance that would later be given to the heart, since, before Aristotle, it was believed to be the origin of blood. It was considered the source of life and divinity, so any damage to the liver was considered lethal, as the ancient poets used to express. In fact, in the Iliad, Hecuba expresses her desire to devour Achilles' liver to avenge the death of her son, without considering the semi-divine condition of the hero. This also showed the facet of the liver as the center of passions, desire and emotions, which should be subdued by the reason located in the head to avoid falling into delusions.

As Plato recounts in Timaeus, divination through the liver compensated for the nature of the aperitive soul that resided in the liver and lacked intellect. Although in Greek divination the liver was just another organ, both in the Middle East and in Etruria it had a special position. This practice originated in Babylonia and Assyria and was transmitted to the Greeks in the Orientalizing period (8th-7th century BC), when the Greeks expanded throughout the Mediterranean and, through their colonies, came into contact with the peoples of the Middle East. The myth of Prometheus told by Hesiod could also have been transmitted at this time, having similarities with the myth of Ziusudra, where Enki warned of the catastrophes sent by Enlil to wipe out humans.

Knowing these details, there would be several reasons that would justify the eagle's attack on the liver. In the first place, Prometheus' deception in the sacrifice in Mecone would reflect how he would have been carried away by emotions. In Prometheus in chains, he himself tells how he taught divination to mankind, where the liver has a prominent position. Finally, the organ devoured by the bird meant the most lethal damage known to the Greeks. In short, the titan became Zeus' sacrifice to the bird, offering him the first organ normally taken in this practice.

Anatomical knowledge

The livers used in hepatoscopy were from animals, since it was considered that, unlike humans, they would not wait for death, so they would not suffer a fear that would affect the premonitory signs. Thanks to this practice, they could recognize the alterations of the hepatic lobes or the portal vein, which they considered the door of the viscera, a detail that has been preserved in their name. This is why the nocturnal regeneration of the organ in Prometheus could be interpreted as a phenomenon observed by the Greeks, but nothing could be further from the truth.

Just as the sharing of an eye by the Graeae does not reflect a knowledge of transplantation, nor is the rebirth of Dionysus through his heart a sign of cloning, the miraculous liver regeneration of Prometheus does not imply that the Greeks knew this function. Although the Greek term hepar (ηπαρ, "liver") originates from the word hepaomai (ηπαομαι, "to cure, repair"), no testimonies are preserved to show that the ancients knew of its regenerative capacity, not even in Hippocrates or Galen.

Modern discovery

The oldest observation of hepatic regeneration was made by the French anatomist Jean Cruveihier (1791-1874) in his description of liver cirrhosis (hepar acinosum), where he mentions the development of acinar zones (grains glanduleux) in contrast to the atrophy of the rest of the organ. Later, for Theodor Ackermann (1825-1986), this regeneration would be limited to the connective tissue of the bile ducts. Friedrich Theodor Frerichs (1819-1885) recognized hypertrophy in syphilitic hepatitis, where the parenchyma, i.e. the specific tissue of the organ, grew and replaced what was lost. However, it was the German pathologist Emil Ponfick who, in 1890, observed that removing a large part of the liver from rabbits without killing them did not alter the liver's capacity. He then found that liver weight recovered in a matter of weeks.

During the 20th century, the factors influencing this regeneration were studied, focusing especially on the blood flow in the portal vein. In 1931, Higgins and Anderson pioneered hepatectomy in rodents, where they proved that the removal of 2/3 of the liver recovered within a week. Nancy L. R. Bucher (1913-2017), with her studies in rats, would demonstrate that the liver did not need stem cells to regenerate, but that the mature hepatocytes themselves, among other cells, were redirected in the remaining organ. Thus, although it can recover its full size, the liver does not recover its lobes if it has lost them. Thanks to her, we also know the involvement of insulin, glucagon, prostanglandins, growth factors and local cell-tissue interactions.

It was not an original sentence

On Phocis and Euboea lived Tycius, a chthonic giant, son of Zeus and Elara. Lest Hera discover his infidelity, Elara hid her son underground, where Gaea nursed him until he grew large enough for his body to cover 9 acres. In another version, Tycius grew so large before birth that he ruptured his mother's womb, whereupon Gaea terminated the pregnancy. As an adult, possibly encouraged by Hera, he attempted to rape Leto as he traveled from Panopeus on the Phocis to Delphi. Hearing his cries, his children Apollo and Diana tried to kill him with their arrows. As he was immortal, Zeus bound him in the underworld, where two vultures fed on his liver, which regenerated.

This myth is possibly older than that of Prometheus, being mentioned in the Odyssey, first by Radamantis and then by Odysseus himself, who sees him in the underworld. In contrast to Prometheus and Chiron, Tyrius would have been considered the worst criminal for the worshippers of the Olympians. Like them, his myth could be connected as his grandson Euphemus, Argonaut, sees Prometheus' eagle circling around the Argo.

In the case of Tycius, the vultures could devour his liver because it is the center of passions and desire, serving as a kind of castration. The symbol of the vulture and its position in the underworld highlighted contempt by not differentiating it from a corpse. Unlike Prometheus' eagle, the vultures came every new moon. In Hyginus' account, instead it was a serpent that devoured his liver.

Sources

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