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We could approach a number of taboos and virtues this way, as well as entire narratives and their relationship to archeological realities.  Briefly, that these lists have their literary and/or historic grounding - if not their factual basis, on how each x typified in groups and out groups that form the contextual basis of said narratives, virtues, and prohibitions.  

Abraham, isaac, and jacob represent nomadic pastoralist communities or sources.  One of the other other major sources (in the ot) being the priestly source.  Genesis, exodus, leviticus, numbers, and the epilogue to dueteronomy.  Dueteronomy as a whole, otoh... it's believed.... is neither pastoralist nor priestly as these communities are pre exile, it is a distinct source or community formed in or after exile specifically curated as the basis of a jewish state and identity that was, at least to it's authors, a continuation of those cultural sources.    What's interesting (to me) is that pretty soon after the exile and post exilic periods..possibly during them, the reason for such prohibitions had been lost - if there ever were some particular reason, in the first place.  The latter notion being one that influential jewish scholars hit on pretty early and often and is prevalent even today in that the contents of holiness may not matter as much as being holy.  So pick a list, any list...and stick with it.    

We can dig deeper, though, and ask ourselves why the pastoralist sources had come to believe that their way of life was better, and to the point where they felt it warranted an explicit bump from god himself to the two archetypes of the competing methods of organization and production at the time (or, at least, the time of the narratives setting).   We find that the list of prohibited items dovetails very nicely with the list of sedentary agricultural products.  In the time between the post exilic source cobbling such rules together and jewish scholars positing that there was never a reason at all they gave many other explanations that would be familiar to us today.  The animals, they contend, were treated poorly.  Not only that, they were spiritually and physically unclean.  Which is to say that they had extreme food safety concerns.  Then, there was quality of life - human life.  Were they warranted?  Certainly, at least in part.  Not only do we have modern examples and systems of agricultural designed to address them - we know from remains that populations of nomadic pastoralists tended to be healthier than the agriculturalist then building some of the first truly large communities that would become dependant on all of the products that would later be taboo according to the pastoralist source..who, back to the above, we believe was writing after that curve had inverted.  Essentially, about the good old days of free grazing.  A similar dynamic expressed itself (and continues to express itself) both in circumstance, outcome, and effect....here, in the us - from westward expansion to today.  The productive angle even leads us back to the cultural angle - both in our own history and in the estalishment myth or legend of the ot - as even the taboos against different types of clothe, and the repeated concerns about race mixing, boil down to production models.  The "races" as we now know, we're not races in the sense of geneticially isolated populations.  These people were cousins at the furthest.  They were "races" in their disparate manner ( and topography) of living, and those goods and products which could identify you (then or now) as a member of either group. 

Let's dive back into the myth, though, to see about that spiritual uncleanliness?   Would the people who manufactured the narratives we find in the ot have any reason to believe that one way of life was favored by the gods?  Perhaps, if we take the narrators of the prophetic books of the ot to be relating some version of a lived experience.  The agricultural and urban development of the region in question drops off a cliff as a consequence of conflict and conquest.  Transportation, it's assumed, also left them short of middle management.  Some of the most extensive and intricate fieldworks around at the time were simply abandoned and the cities they supported were depopulated.  Perhaps not to the extent reported - but lets not minimize the consequences of sudden population loss and brain drain.  The hillholding shepherds and their culture persisted without interruption or significant change for the duration of the exilic period, relatively speaking.  It didn't help, from these purist's view, that agricultural cultures and cities in early development tended to assume agricultural deities and idols and idiosyncrasies in addition to their race mixing and the taboo behaviors these things were believed to produce.  Exile is narrativized, by those communities or authors or sources, as a just judgement by a wrathful god for a degenerate people.

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