Okay, I know this question has come up many many times before. But let's approach one more time.
Yet this is held true by the wise of Eressea, that all those of the Quendi who came into the hands of Melkor, ere Utumno was broken, were put there in prison, and by slow arts of cruelty were corrupted and enslaved; and thus did Melkor breed the hideous race of Orcs in mockery and envy of the Elves, of whom they were afterwards the bitterest foes
Of the Coming of Elves, The Silmarillion
Tolkien told us here that all Orcs are descended from corrupted Elves. But Elves breed sexually... I doubt that Melkor could have changed THAT much about the basic life form. Besides, what other ways are there to reproduce? Did orcs bud asexually? Seeds? If you cut off an orc's arm and plant it in the ground, would it emerge a few months later as a fully grown new orc? These may sound like silly ideas, but I'm desperately trying to come up with anything other than sexual reproduction.
Because for sexual reproduction, there have to be female orcs. And baby orcs. And nurseries to care for the babies. And some sort of hint of sexual drive from the males. Truth is, all we've ever seen anywhere are male orcs. And all they seem to complain about is food and rest, or lack thereof. Usually a motivating factor for a large conquering army in the past would be ransacking a captive village and raping the women. Yet the orcs seemingly have no desire for women, human or otherwise. It doesn't quite make sense.
However, I should note that in The Hobbit, there is clearly a mention of Orc reproduction by setting up Bolg as "the son of Azog". Not only is he a biological son, he also inheirits Azog's position and power, which implies that Orcs recognize and attach importance to biological lineage/parentage that can only arise from sexual reproduction. But by the time he writes the Lord of the Rings, Tolkien's views seem to have changed, because Orcs no longer seem to have "sons" but are "bred" by an overseeing power, be it Sauron or Saruman. It is nowhere mentioned that an Orc has a family; a son or a father, or anything else. It seems rather that they were mass-bred like clones. Here's some more food for thought: why did Tolkien's description of Orc-breeding change from The Hobbit to LOTR?
Clearly seeking an immediately understandable and visual answer for this issue, Peter Jackson interpreted Uruk-hai "breeding" as Uruks emerging fully grown from sacs in the ground. The Uruks were supposedly crossbreeds between Men and Orcs, but that again doesn't make sense because we know Men reproduce sexually. How could an asexual and a sexual species "breed"?
Science can't be the answer, either, because it's not like Saruman had a fully equipped genetics lab to play around with. Unlike today, he couldn't insert Man genes into Orc genes and then grow an embryo in a test tube. Either he did it the old fashioned way (sex) or it's all MAGIC, in which case this argument is moot.
So, what do you think? Either it's sexual, in which case we have a host of problems/issues not addressed in the book, or it's MAGIC/something else which we can't fathom.
