Lorendiac

This stirs up memories of a theory I think I had once, a few years ago, about dangers of "inbreeding" and why it didn't wipe out certain societies over the years. (I may have formed this theory about some other piece of literature and the distant ancestors of the characters, but I'll just file off a few serial numbers, splash on a little paint, and call it an Arda-specific theory instead!)

What if the "original ancestors" of each species -- those 13 Dwarves, for instance -- were created to be "genetically perfect"? No nasty recessive genes that could pile up in the first few generations to create numerous children who had visible and handicapping physical defects, serious heart trouble, terrible eyesight, hemophilia, etc.? So if you had first cousins (or second, or third cousins) marrying back and forth in the early days, it wouldn't cause much trouble until nasty mutations started to creep in. Either by accident in the natural course of events, or else because of the well-known corrupting influence of the Shadow. (Or some of each?)

As near as I can recall, some of Tolkien's writings suggested Orcs and Trolls were basically bred from the original Elf and Men stock by Morgoth, using prisoners he'd captured and then tinkered with somehow at his leisure, way back in the day. Obviously he was able to make some drastic changes along the way to make sure future generations "bred true" with their new forms and characteristics. I've read claims that other notes Tolkien made at different times suggest that he also played around with the idea that those critters weren't long-lost "cousins" of Elves and Men, but merely second-rate imitations somehow created by Morgoth from scratch to make better servants. Either way, they were obviously living creatures that could reproduce themselves, and if Morgoth were to achieve such a thing in the modern world we'd say he had considerable ability in "genetic engineering" (although he probably didn't call it that and may not have known a thing about the structure of tiny little DNA molecules. Maybe he just knew how to really exert his willpower to get roughly the results he wanted? Mind over matter?)

If we grant Morgoth the "genetic engineering" capability, why not assume that nasty genes that eventually crept into the gene pools of one species or another were the result of his evil influence? Whether his magic had an effect similar to powerful radiation, or whether he was putting nasty mutagenic substances into water supplies (rivers, lakes, etc.), or whether he released a few retroviruses or some such thing out into the world . . . anything that would gradually cause visible defects (and sometimes defects not visible to the naked eye) to weaken the future generations of Men, Elves, Dwarves? Particularly if they inbred over time? Frequently marrying cousins back and forth within a rural community over a span of centuries, for instance?

That would explain why the Dwarves, for instance, didn't run into serious trouble in the first several generations when they were all descended from the same six married couples or however it worked. (Six married couples plus Durin? Did Durin later marry someone else's daughter?) The mutations triggered by Morgoth hadn't had much time to sink into their gene pool yet. By the time you had a nasty recessive gene lurking in one House or another, marrying a member of another House would probably keep it lurking recessively, unknown and unworried about, for a few generations longer until at long last it was potentially "reunited" with a copy of itself in a new marriage and then the two would have one chance in four of being able to pair together in a particular kid and make his life less happy than it otherwise would have been?