Actually, we are led to reconstruct two myths: one European and one Indo-Iranian, both of which are quite similar and are closely related. In both of them, the world begins with a pair of twins, *Manu, "Man," and *Yemo, "Twin," *Yemo being characterized as the first king, while *Manu is the first priest, and in the course of the myth, *Manu offers *Yemo as the first sacrificial victim. As a result of this sacrifice, the world is created, and *Manu fashions the earth and heavens, as well as the three social classes from his brother's body. In the I-I version, an ox or bull, a male bovine, is offered along with *Yemo, and from the body of this animal all the other animal and vegetable species are created. In the European version, however, a female bovine, a cow, appears, and merely functions to feed and care for the twins prior to the act of creation. Given this reconstruction, we may now properly consider the meaning of the myth.
https://www.researchgate.net/publication/316981510_The_Indo-Europeans_Myth_of_Creation