[Fordim Hedgethistle]

I've always just figured that since Morgoth was all about corruption and mockery that he would pretty much take whatever he could find, break it, and make it monstrous -- so I see no reason against having all the theories of orc origin at once. The orcs are a hybrid, bastard race drawn from ruined Elves, enslaved men, beasts, unnatural arts and perhaps another race (or races?) of beings that he found and took for his own. This might also help explain where there is such a diversity of forms, sizes, abilities, types and races among the orcs...