The Orphic prohibition on eating certain animals isn’t vegetarianism (though it was sometimes mistaken for such in antiquity) nor is it driven by sentimentality – it is straight up a taboo in the Frazerian sense. The concern wasn’t for the preservation of life (which is why they had no problem participating in animal sacrifice) but rather the effect that consuming the animal’s soul would have on the individual – since that was actually part of the telete.

This is made clear in the original Greek – in the rare instances when you find Orphics mentioned in conjunction with abstention from meat (and that rarity should tell us something, since vegetarians wouldn’t have missed the opportunity to enshroud their beliefs in the authority of a figure like Orpheus if they could) what they are avoiding is flesh that is empsuchos “ensouled” not “alive” zōntes or something similar. Notably, in Homer, psuchai are something we possess only in death, a sort of spiritual double that’s produced when the body ceases to respirate and is sent down to the house of Haides. This concept changed drastically under the Presocratics until it came to have its contemporary psychological associations – but Orphism was self-consciously Homeric and pre-Homeric in its orientation. (Most Orphic literature, even in the late period, was produced in strict dactylic hexameters and there are strong, and rather ironic, borrowings from Homer in the gold lamellae.) So I think Orphics were drawing on primitive (one might even say shamanic considering the region where the tradition originated) notions of the soul as a repository of qualities and consciousness that could migrate from one body to another. Thus by eating an animal one would take on the soul of that animal, including its powers, personality and behaviors. So, for instance, when we find prohibitions such as these:

Those who are mages (magoi) and purifiers (kathartai) and beggar-priests (agurtai) and vagrant-charlatans (alazones) purport to be extremely reverent of the gods and to know something more than the rest of us. They use the divine to hide behind and to cloak the fact that they have nothing to apply to disease that will bring relief. So that their ignorance should not become manifest, they promoted the belief that disease was sacred. They added further appropriate arguments to render their method of healing safe for themselves. They applied purifications (katharmoi) and incantations (epaoidai) and told people to refrain from bathing and many foods unsuitable for the sick to eat: among fish they banned red mullet, black-tail, grey mullet, and eel (for these are the most hazardous); among meats goat, venison, pork and dog (for these are the meats that upset the stomach most); among poultry cock, pigeon, the otis-bird and all those birds considered to be least indigestible; among vegetables mint, garlic, and onions (their sharpness is deleterious for a sick man). They also forbade the wearing of a black cloak (for black is deathly), the lying on or wearing of goatskin, the placing of foot upon foot or hand upon hand (for this is shackling). (Hippocrates, On the Sacred Disease 1.11–18)

We can see the laws of sympatheia and contagion at work here. These specific animals are singled out for what they represent which was situationally undesirable, particularly since the recommendations are being made for a client who is suffering from illness. In other contexts one might actually want to become a goat or a bull and thus would consume their flesh in order to draw the animals’ souls into them. Seen in this light several Orphic texts suddenly take on a whole new meaning:

Where midnight Zagreus roves, I rove; I have endured his thunder-cry; fulfilled his red and bleeding feasts; held the Great Mother’s mountain flame; I am set free and named by name a Bakchos of the Mailed Priests. Having all-white garments, I flee the birth of mortals and, not nearing the place of corpses, I guard myself against the eating of ensouled flesh. (Euripides, Cretans fragment 472)

Now you have died and now you have been born, thrice blessed one, on this very day. Say to Persephone that Bakchios himself freed you. A bull you rushed to milk. Quickly, you rushed to milk. A ram you fell into milk. You have wine as your fortunate honor. And rites await you beneath the earth, just as the other blessed ones. (Gold tablet from Pelinna)

Accept ye my great offering as the payment for my lawless fathers.
Save me, great Brimo …
and Demeter and Rhea …
and the armed Kouretes: let us … and we will make fine sacrifices.
A ram and a he-goat … boundless gifts.
… and by the law of the river …
Taking of the goat … let him eat the rest of the meat …
Let no uninitiated look on!
(The Gurôb Papyrus)

So there may have been a taboo not just on eating certain animals – but on eating them outside of ritual or before rituals where a different sort of energy was required. 

And a mythic prototype of this would naturally have been the metamorphoses described by Nonnos in the sixth book of his Dionysiaka:

He appeared in another shape, and changed into many forms: now young like crafty Kronides shaking the aegis-cape, now as ancient Kronos heavy-kneed, pouring rain. Sometimes he was a curiously formed baby, sometimes like a mad youth with the flower of the first down marking his rounded chin with black. Again, a mimic lion he uttered a horrible roar in furious rage from a wild snarling throat, as he lifted a neck shadowed by a thick mane, marking his body on both sides with the self-striking whip of a tail which flickered about over his hairy back. Next, he left the shape of a lion’s looks and let out a ringing neigh, now like an unbroken horse that lifts his neck on high to shake out the imperious tooth of the bit, and rubbing, whitened his cheek with hoary foam. Sometimes he poured out a whistling hiss from his mouth, a curling horned serpent covered with scales, darting out his tongue from his gaping throat, and leaping upon the grim head of some Titan encircled his neck in snaky spiral coils. Then he left the shape of the restless crawler and became a tiger with gay stripes on his body; or again like a bull emitting a counterfeit roar from his mouth he butted the Titanes with sharp horn. So he fought for his life, until Hera with jealous throat bellowed harshly through the air–that heavy-resentful step-mother! And the gates of Olympos rattled in echo to her jealous throat from high heaven. Then the bold bull collapsed: the murderers each eager for his turn with the knife chopt piecemeal the bull-shaped Dionysos.

As well as the vision of Platonic revenant Er who described a musical orgy during which Orpheus was transformed into a swan and Thamyras a nightingale and a bird became a man in a “strange, pitiful ridiculous spectacle.” (Republic 10.620a)

The profound identification of eater with eaten which lies at the heart of omophagia was too much for certain sensitive individuals such as Empedokles:

Will ye not cease from this ill-sounding slaughter? See ye not that ye are devouring one another in the thoughtlessness of your hearts? […] And the father lifts up his own son in a changed form and slays him with a prayer. Infatuated fool! And they run up to the sacrificers, begging mercy, while he, deaf to their cries, slaughters them in his halls and gets ready the evil feast. In like manner does the son seize his father, and children their mother, tear out their life and eat the kindred flesh. […] Draining their life with bronze. […] Ah, woe is me that the pitiless day of death did not destroy me ere ever I wrought evil deeds of devouring with my lips! (fragments 136-39)

And like someone reeling from a bad acid trip who swears off all drugs, he rejected the core sacrament of Orphism after going through it. This sarcophobic strain enters Pythagoreanism in the second or third generation and gives rise to the soma-sema tag “the body is a tomb” which dominates Neo-Pythagoreanism, Neoplatonism and certain branches of Orphism (such as the ones that emphasize Apollon or Zeus above Dionysos and Persephone) to the end of antiquity. But death as a transition from one state of life to another and sacramental theriomorphism remained hallmarks of Bacchic Orphism and related Dionysiac traditions.

Like tarantism, which seems to be the process in reverse. Instead of becoming what you bite, you become what bites you.

Gilbert Rouget writes in Music and Trance: A theory of the relations between music and possession:

One of the dance figures of the tarantulees – the best known – consists, as we know, in imitating the spider’s movements: back to the ground, body arched to a great or lesser degree, the tarantulee moves about like a spider on all fours. One can see this very clearly in D. Carpitella’s film, and the sight is striking […] Despite appearances, the divinity responsible for the possession is not the one that is excorcised. On the contrary, it is the divinity concerned who, by allowing the possessing person to identify with him or her, provides the means of ecxorcising the illness – real or imagined – from which the person is suffering.

Elaborating on this, blogger quotidian banality writes:

The spider which was held responsible for tarantism was a mythical creature which did not correspond to any arachnid of modern zoology. Instead, the taranta assembled the characteristics of several different species of spider into a mythical whole. Different colours were attributed to the spiders – principally red, green and black – and the ‘bite’ of each respective spider caused different behaviour in the victim. Those bit by red spiders displayed martial, heroic behaviour; those bit by green spiders displayed eroticised behaviour; and those bitten by black spiders were fascinated by funerary paraphernalia. Furthermore, each colour spider had its own repertoire of musical figures and dances: for example, those bitten by a green spider would only dance to a tarantella tune associated with the green spider. Finally, the victims of the spider’s bite were fascinated by pieces of cloth with the appropriate colour. Thus, during the course of an exorcism different Tarantella tunes were played and different colours of clothes were given to the victim in order to determine which spider possesses her. Only the appropriate tarantella tune, the appropriate colour and the appropriate dance would cure the victim – at least for the time being, until the affliction reoccured a year later. Music serves at once as diagnosis and therapy.

Which hearkens back to what I was saying about sympatheia and contagion earlier. 

And circles make me think of labyrinths which makes me wonder – if eating animals makes us bestial, by eating human flesh did Asterion become more man-like?