Where did the Orcs come from?

[Galin]

Originally Posted by Matoro

(...) Did Tolkien ever address a problem of Orcs being made from Men but still being around before the Men had awakened? IIRC, in his late writings orcs weren't anymore made from Elves.

In text X, Myths Transformed, Tolkien has altered the timeline and the Awakening of Men [to simplify things here for brevity]. The author of this text still seems to find the [revised] chronology somewhat problematic, but concludes that the theory [Orcs from Men] is nonetheless the most probable.

Also Tolkien introduced Orc-formed Maiar into the mix, and these type [at least] could be around in Middle-earth quite early.