The Indo-European cosmogony refers to the creation myth of the reconstructed Proto-Indo-European mythology.
The comparative analysis of different Indo-European tales has led scholars to reconstruct an original Proto-Indo-European creation myth involving twin brothers, * ('Man') and * ('Twin'), as the progenitors of the world and mankind, and a hero named * ('Third') who ensured the continuity of the original sacrifice.
Although some thematic parallels can be made with Ancient Near East (the primordial couple Adam and Eve), and even Polynesian or South American legends, the linguistic correspondences found in descendant cognates of *Manu and *Yemo make it very likely that the myth discussed here has a Proto-Indo-European (PIE) origin.
Historiography
Hermann Güntert, stressing philological parallels between the Germanic and Indo-Iranian texts, argued in 1923 for an inherited Indo-European motif of the creation of the world from the sacrifice and dismemberment of a primordial androgyne.
Following a first paper on the cosmogonical legend of Manu and Yemo, published simultaneously with Jaan Puhvel in 1975 (who pointed out the Roman reflex of the story), Bruce Lincoln assembled the initial part of the myth with the legend of the third man Trito in a single ancestral motif.
Since the 1970s, the reconstructed motifs of Manu and Yemo, and to a lesser extent that of Trito, have been generally accepted among scholars.
Myths
Primordial state
The basic Indo-European root for the divine creation is *dheh1, 'to set in place, lay down, or establish', as attested in the Hittite expression nēbis dēgan dāir ("...established heaven (and) earth"), the Young Avestan formula kə huvāpå raocåscā dāt təmåscā? ("What skillful artificer made the regions of light and dark?"), the name of the Vedic creator god Dhātr, and possibly in the Greek name Thetis, presented as a demiurgical goddess in Alcman's poetry. The concept of the Cosmic Egg, symbolizing the primordial state from which the universe arises, is also found in many Indo-European creation myths. A similar depiction of the appearance of the universe before the act of creation is given in the Vedic, Germanic and, at least partly, in the Greek tradition.
Although the idea of a created world is untypical of early Greek thinking, similar descriptions have been highlighted in Aristophanes's The Birds: "...there was Chasm and Night and dark Erebos at first, and broad Tartarus, but earth nor air nor heaven there was..." The analogy between the Greek Χάος ('Chaos, Chasm') and the Norse Ginnungagap ('Gaping abyss') has also been noted by scholars. The importance of heat in Germanic creation myths has also been compared with similar Indian beliefs emphasized in the Vedic hymn on 'cosmic heat'.
Cosmic sacrifice
The first man Manu and his giant twin Yemo are crossing the cosmos, accompanied by a primordial cow. To create the world, Manu sacrifices his brother and, with the help of heavenly deities (the Sky-Father, the Storm-God and the Divine Twins), forges both the natural elements and human beings from his twin's remains.
Manu thus becomes the first priest after initiating sacrifice as the primordial condition for the world order. His deceased brother Yemo turns into the first king as social classes emerge from his anatomy (priesthood from his head, the warrior class from his breast and arms, and the commoners from his sexual organs and legs).
Although the European and Indo-Iranian versions differ on this matter, the primeval cow was most likely sacrificed in the original myth, giving birth to the other animals and vegetables. Yemo may have become the King of the Otherworld, the realm of the dead, as the first mortal to die in the primordial sacrifice, a role suggested by the Indo-Iranian and, to a lesser extent, in the Germanic, Greek and Celtic traditions.
First Warrior
To the third man Trito, the celestial gods offer cattle as a divine gift, which is stolen by a three-headed serpent named * ('serpent'; and the Indo-European root for negation).
Trito first suffers at his hands, but fortified by an intoxicating drink and aided by a helper-god (the Storm-God or *Haner, 'Man'), together they go to a cave or a mountain, and the hero finally manages to overcome the monster. Trito then gives the recovered cattle back to a priest for it to be properly sacrificed. He is now the first warrior, maintaining through his heroic deeds the cycle of mutual giving between gods and mortals.