In the story of the creation of Adam and Eve, we are told that G-d took a rib from Adam and from that created the woman. It is written, “And the Lord G-d caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof; and from the rib, which the Lord G-d had taken from man, He built a woman, and brought her to the man” (Genesis 2:21-22).
The sages discuss which rib and what organ G-d took from Adam. One sage argued that he took Adam’s tail and used that to create the woman. Another sage argued that he split off the woman’s face, for in his opinion Adam was created with two faces, before and behind, back to back, and G-d split Adam in half; this is the rib that he took. The scholars ask:
According to the sage who argues that Adam was created with two faces, man and woman before and behind, this is the reason why the Scriptures doubled the letter yud in the word vayitzer (and He created). One yud is for the man, and one for the woman. But according to the sage who argued that what G-d took was a tail, why is the word written with two yuds? Answer: The duplication of the letter is meant to teach that man is caught between two opposing forces — G-d and the evil inclination. As the sages put it, “Woe tם me because of my inclinations, and woe to me because of my Creator.” The scholars went on to ask: according to the sage who says that the “rib” was a tail, implying that first man was created and only after was woman, how can we explain the verse “Male and female created He them?” Answer: At first G-d thought to create two — male and female — but in the end He created only the male, and from the male created the female. The scholars then asked: according to the sage who states man had two faces and that G-d simply split the being in half, how can we explain the verse “And G-d built up the rib,” meaning that G-d built the woman? Answer: After G-d separated the male and the female, he plaited the hair of the woman (Eve) to adorn her for man. Plaiting is, in foreign languages, called building. Another possibility for why the Scriptures call the division between male and female building is that after G-d separated Eve from Adam he formed her into a conical shape, narrower on top (the chest) and wider on the bottom (the pelvis) so there would be space for a fetus to develop. The scholars continued with their questions: according to the sage who says man had two faces — male and female connected back to back — who led the way? Answer: it is reasonable to suppose that the male led the way and that Eve, the female, was pulled along behind him, for the sages said “A man should not follow a woman along the road, not even his wife.”
(Babylonian Talmud, Tractate Berachot 61a)