The Brhadaranyaka Upanishad, in the first three verses of the Fourth Brahmana in section one, describes the birth of the conception of “I” with the development of self-awareness in the first man of the universe (the purusa)—this event is followed by the creation of the first female, and then through the union of the first male and the first female, there is the rise of the human race. Here’s a translation of verse 1.4.1 which talks about the rise of the purusa:
“In the beginning this (universe) was only the self in the likeness of purusa. Looking around the purusa could see nothing else except himself. He spoke his first words, “I am.” Thus at that moment the name I was born. From that moment onwards, it became a tradition that when anyone is addressed, he first says, “This is I” and then he might speak of the other name that he might have. Since before all this, he burnt every evil from everything, he is the purusa. Whoever knows this, verily, burns up all those who wish to be before him.”
When the purusa, who is described in the Vedic and Upanishadic texts as Hiraṇyagarbha or Prajapati, utters the words, “I am,” it seems that he is committing an act of duality—for to say, “I am,” is to be aware of the existence of something that is not I and to be aware of the boundaries of one’s ego. But nothing else is in existence except the purusa—he is all that exists; he is the universe—that is why the verse talks about the burning of all those who wish to be before him. There cannot be anything before or after him, since the universe is contained inside him.
The first emotion that the purusa feels is described in verse 1.4.2—this is the emotion of fear:
“The purusa was afraid. Thus the tradition began of the people who are alone feeling afraid. Then the question entered his mind, “Since there is nothing else other than I what am I afraid of?” His fears departed, since there was nothing in existence of which he could be fearful. Only when something other than the I exists that there might be a cause for fear.”
Verse 1.4.3 talks about the second and third emotions that the purusa feels, the feeling of loneliness and the desire for a companion—it also describes the birth of the second person, the female form:
“He did not feel happy since he was lonely. Thus the tradition began of people who are lonely feeling unhappy. He yearned for a second person who could be his companion. He made himself large and assumed the posture of a man and woman in tight embrace, and then his self split into two parts: one part was the pati (husband) and the second part was patni (wife). This is as Sage Yagnavalkya used to say, “In this respect, we are like the one half of a single person, or like one of the two halves of a split pea.” Thus the purusa had the companionship of his wife and through their union the human beings were produced.”
The verses which follow in Brhadaranyaka Upanishad’s Fourth Brahmana of section one describe the birth of other creatures of the universe and the establishment of the moral and political systems which will enable the human beings to create a society where they can live righteously. On a side note—the notion of the human race evolving from a first man who is androgynous was popular in Ancient Greece. In his dialogue Symposium, Plato talks about the androgynous male who splits into two and mates with his other half to produce the human race.