"Almah (עלמה, plural: alamot עלמות) is a Hebrew word meaning a young woman of childbearing age who has not yet had a child, and who may be an unmarried virgin or a married young woman."

I'm not saying that Wikipedia gets the final say here, just pointing out what the quoted article says.

I'm not sure they would have drawn a line between the two at that point (hence why I as too lazy to look up when they wed). Shotgun weddings were not considered having children out of wedlock for western europe, and further back you see it's more of an economic agreement to father all the woman's children. In fact, it's entirely possible marriages would have been more of de-facto arrangements based around paternity for non-arranged marriages (which are economic transactions).

EDIT: it's insinuated he's upset because she's pregnant and they haven't had sex, but they had already been married. Again, at this point, it's more of a question of semantics of the time as to whether it counts as adultery or pre-marriage pregnancy. Historically, there may be other evidence to point one way or the other, but I don't think it matters much to joseph (or to christians).

18 Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost.

19 Then Joseph her husband, being a just man, and not willing to make her a public example, was minded to put her away privily.

I agree whole-heartedly; however, books are far from the only thing that drive language. Most of the world didn't have access to books until very recently, and language is driven by that most of the world (to some extent, it's difficult to say how much).

> Given that males provided protection and resources during child rearing, I suspect there would have been strong selective pressure for males that tried to ensure that the children they supported were their own.

Careful, you're treading into "let's speculate about how genetics and society interact" territory, which is basically impossible to do correctly without many generations of evidence. Males do provide protection in many cultures, but women provide many forms of protection and resources as well. Among other things (which vary from culture to culture), they provide men. Matrilineal societies are attested many times over, as are matriarchal societies. Given that there are no reliable signals for virginity, it's quite easy to see how men might lust after young women instead of "the first sex". Furthermore, I would (again) argue that "the first sex" is by far most valuable in patrilineal societies. In societies where resources are scarce, for instance, polyandrous societies are more common, because it's more important that individual children are given the appropriate nutrition and protection than it is to ensure that the birth rate is maximized. In these situations, who the real father is is not important, because it's one of the child's caretakers (de-facto). Furthermore, male status is tied to children, so there is more impetus to protect existing children than there is to ascertain paternity.

It takes a classical understanding of lust for the classical interdiction to make sense:

https://www.google.com/search?site=&source=hp&ei=9aidVJHyC8O...