Warm Beds Are Good fails to grapple with the most interesting question of all, however, which is how Arwen and Aragorn could possibly have developed the hots for each other in the first place. It turns out to be rather hard to come up with any theory of Elvish reproductive biology under which Arwen’s behavior makes any sense at all.

Aragorn’s end isn’t that much of a mystery. He’s an alpha male of a warrior culture, chock full o’ testosterone and other dominance hormones guaranteed to make him into a serious horn-dog. She’s a beautiful princess, broadcasting human-compatible health-and-fertility signals in all directions. If she doesn’t actively smell bad, tab A fits slot B just fine from the point of view of his mating instincts.

No, the fundamental problem is Arwen’s lifespan. She is supposedly something like two thousand, seven hundred years old when she meets Aragorn. That’s an awful lot of Saturday nights at the Last Homely Disco West of the Mountains; if she has a sex drive anything like a normal human female’s, she ought to have more mileage on her than a Liberian tramp steamer. On the other hand, if her sexual wiring is fundamentally different from a human female’s, what’n’the hell is she doing with Aragorn? He shouldn’t look or smell or behave right to trigger her releasers, any more than a talking chimpanzee would to most human women.

“B-b-but…” I hear you splutter “This is fantasy!”, to which I say foo! Tolkien was very careful about logical consistency in areas where he was equipped by temperament and training to appreciate it; he invented a cosmology, thousand of years of history, multiple languages; he drew maps. He lectured on the importance of a having convincing and consistent secondary world in fantasy. Furthermore, Tolkien never completely repudiated the intention that his fiction was a mythic description of the lost past of our Earth, and that therefore matter, energy and life should be consistent with the forms in which we know them.

Therefore, it is entirely appropriate to analyze Middle-Earth as though it were a science-fictional creation, to assume Elves and Men both got DNA, and to ask if the freakin’ biology makes any sense at all under this assumption.

And one of the facts we have to deal with is that humans and elves are not just interfertile, they produce fertile offspring. That means they have to be genetically very, very similar. If there are dramatic differences between elf and human reproductive behavior, the instinctive basis for them must be coded in a relatively small set of genes that somehow don’t interfere with that interfertility. In fact, technically, Elves and Men have to be subspecies of the same stock.

When this came up on my favorite mailing list just after the first movie came out, my hypothesis was that elves (a) have only rare periods of vulnerability to sexual impulses, and (b) imprint on each other for life when they mate, like swans. This pattern is actually within the envelope of human variation, though uncommon — which makes it a plausible candidate for being dominant in another hominid subspecies.

This ‘swan theory’ would be consistent with Appendix A, which (a) has Arwen meeting Aragorn when he was garbed like an elven prince and (as near as we can tell through Tolkien’s rather clotted chansons-de-geste style) falling for him hard right then and there, and (b) has Arwen’s family apparently operating under the assumption that once that had happened, the damage was done and she wouldn’t be mating with anyone else, noway, nohow.

One of the techies on the list shot the swan theory down by finding a canonical instance of an Elf remarrying (Finwe, father of Feanor; first wife Miriel, second Indis). In subsequent discussion, we concluded that it wasn’t possible to frame a consistent theory that fit Tolkien’s facts. The sticking-point turned out to be the half-elven; Tolkien tells us that they get to choose whether they will have the nature of Men or Elves, and it is implied that they do so at puberty.

Since that’s true, the difference between Men and Elves can’t properly be genetic at all. It must be in the cloudy realm of spirit, magic, and divine interventions. This is not an area in which Tolkien (a devout Catholic) gives us any rules or regularities at all. Elvish sexual behavior could be arbitrarily variant from human without any reasons other than that Eru keeps exerting his will to make it so, and He very well might be intervening to keep elf-maidens’ hormones from getting them jiggy Until It’s Time.

Helluva way to run a universe, say I. Inelegant. A really craftsmanlike god would build his cosmos so it wouldn’t require constant divine intervention to function. It’s a serious weakness in Tolkien’s fiction, one that runs far deeper than anachronisms like domestic cats (which didn’t reach northern Europe until late Roman times) and tea (to Europe in 1610) in the Shire.

Eric S. Raymond, “Sex and Tolkien”, Armed and Dangerous, 2003-12-18.