There probably should be a citation to Thomas Laqueur, who originated the idea of the one-sex model in his 1990 book, Making Sex: Body and Gender from the Greeks to Freud.
Linguistically, man and woman are binary opposites, similar to black and white, good and evil, up and down, etc. The best discussion of binary opposition is provided by Ferdinand de Saussure, the Father of Modern Linguistics and the most influential thinker of the twentieth century. But in his focus on synchronic linguistics, he did not explore the origins of binary opposition thinking. Seventh-day Adventists, if they were to learn linguistics, are in the best position to explain those origins: the fall of Lucifer.
Before the fall of Lucifer, there was no right and wrong, no law, no worship, no hierarchy, no critical thinking, no conception of god, and no binary opposites. Although the neophyte can conceptualize that before food was ever cooked, there was no conception of cooked food, an understanding of linguistics informs us that there was also perforce no conception of raw food. (Claude Levi-Strauss). Similarly, if there was no conception of evil before Lucifer’s fall, there was no conception of good. Granted reality and a linguistic construct are not necessarily the same thing–(although God would have never been conceptualized as good before the fall of Lucifer, God was good)–but many aspects of reality are dictated by linguistic constructs. For example, there can be no reality of worship if there is no conception of worship. As per Gadamer, “Being that can be understood is language.”
The fall of Lucifer and the resultant binary opposite of good and evil revolutionized the language of heaven from a dictionary mode of language–(every aspect of reality has its own particular word)–to the structural mode of language we have today. Heavenly reality before Lucifer’s fall was unstructured, static, and undifferentiated. And there was no critical thinking of any kind. The best comparison we can make of a pre-fall angel is to a baby who is full of wonder as the world unfolds.
The language of binary opposition was God’s way of teaching us what Lucifer did. And is. Differences are not necessarily binary opposites, but some differences are. This divine teaching mechanism of binary opposition predominates in the Genesis stories of Creation. Binary opposites are everywhere. But the binary opposition of man and woman has an interesting paradox that Seventh-day Adventists have not completely appreciated. Man and woman in marriage become one, one flesh, echad. Binary opposites by definition cannot become reconciled in this way. So how can man and woman do what they cannot do by definition? This speaks to hope, to a universe that is no longer affected by sin, to the former mode of language that existed before sin, to an unwinding back to that baby who is full of wonder as the world unfolds.