Originally,
orcs were
elves captured by
Morgoth, whom he tortured until they became orcs, so I assume that the orcs bred amongst each other.
Something I've been wondering about was whether the orcs are still immortal like the elves are, or if they lost their immortality by being so horribly twisted and marred.
This has really sparked my interest. My immediate response is 'No! Have you ever seen an old
orc?' but then, the people in charge of the orcs (ie
Melkor,
Sauron and to a lesser extent
Saruman) never keep them long enough for us to know this, they're just disposable tools for one time use. Perhaps if an orc was treated 'right' and allowed to grow, perhaps they would last a very long time. For even the elves could die from a grievous bodily injury, or waste away in grief (though I can't see an Orc crying itself to sleep). Thought provoking indeed. Perhaps the orcs really have an intellect rivalling that of elves? Okay,
men then. Now that is heartbreaking.
As for born or grown; I would say born. We know that the first orcs were twisted elves, and being of the same species I expect they can still interbreed, and I'm sure I've seen it in one of the texts that Melkor or Sauron 'bred' an army. As for Saruman's creation of
Uruk-Hai seemingly from mud in the film adaption, I think this is misleading. In The Two
Towers (book),
Treebeard alludes to Uruk-Hai being a hybrid of orc and human (Wildmen of
Dunland). Now, think about the way some
animals create nurseries for their young before they are born. This could be the mud-vats of Saruman, a place for
the young foetus to grow outside of the body. I don't actually know how Orc breeding works, but that's one theory, that orcs are bred but then developed externally. I can;t quite grasp the notion of a pregnant,
female orc. It's uncomfortable.