Wenn man übrigen den typischen Maßstab „Tolkiens spätere Ideen stechen seine früheren“ anlegt, stammen Orks nicht von Elben ab (obwohl mir persönlich die Idee recht gut gefällt). In chronologischer Reihenfolge:
Schlamm & Stein (~1920): „for all that race were bred by Melko of the subterranean heats and slime. Their hearts were of granite and their bodies deformed.“ (LT2:159)
Elben (~1950): „Yet this is held true by the wise of Eressëa: that all those of the Quendi that came into the hands of Melkor, ere Utumno was broken, were put there in prison, and by slow arts of cruelty and wickedness were corrupted and enslaved. Thus did Melkor breed the hideous race of the Orkor in envy and mockery of the Eldar, of whom they were afterwards the bitterest foes.“ (MR:73f.)
Sprechende Tiere (~1959): „In any case Elves, as a source, are very unlikely. [...] I think it must be assumed that ‘talking’ is not necessarily the sign of possession of a ‘rational soul’ or fea. The Orks were beasts of humanized shape“ (MR:409f.)
Elben, Menschen & Maia (?): „Most of them plainly (and biologically) were corruptions of Elves (and probably later also of Men). but always among them (as special servants and spies to Melkor, and as leaders) there must ahve been numerous corrupted minor spirits who assumed similar bodily shapes)“ (MR:414)
Menschen (~1959-1960): „This view of the origine of the Orcs thus meets with difficulties of chronology. But though Men may take comfort in this, the theory remains nonetheless the most probable. It is in accord with all that is known of Melkor, of the nature and behaviour of Orcs — and of Men. [...] Finally, there is a cogent point, though horrible to relate. It became clear in time that undoubted Men could under the domination of Morgoth or his agents in a few generations be reduced almost to the Orc-level of mind and habits; and then they would or could be made to mate with Orcs, producing new breeds, often larger and more cunning. There is no doubt that long afterwards, in the Third Age, Saruman rediscovered this, or learned of it in lore, and in his lust for mastery committed this, his wickedest deed: the interbreeding of Orcs and Men, producing both Men-orcs large and cunning, and Orc-men treacherous and vile.“ (MR:417f.)
Das grundätzliche Problem für Tolkien scheint wohl gewesen zu sein, dass Melkor keine eigenen Kreaturen mit Seele/Verstand erschaffen kann, aber Orks eine zu haben scheinen und Eru ja wohl nicht zugelassen haben kann, dass Melkor seine Kinder zu Orks macht (obwohl das bei Menschen ein weniger großes Problem gewesen zu sein scheint als bei Elben...). Und dass es Orkfrauen gibt ist wirklich keine Frage, da bin ich ganz bei Drachentöter, dass der Aufschrei ein bisschen absurd ist. Unter (2) gibt es „For the Orkor had life and multiplied after the manner of the Children of Ilúvatar“ und bei (5) steht es ja quasi schon explizit da.
Dazu, dass Tolkien nur selten Frauen erwähnt habe ich letztens diesen Sketch über Tolkien und Lewis gefunden (der nichts mit der Serie zu tun hat und auch nicht völlig akkurat ist, aber ich fand ihn witzig).