I too have been wondering where those Dwarves got all of their food. Think of the fair city of the Dwarrowdelf - in its hay day, more than a few busy dwarves lived there. Did they eat much of what Hollin produced? Then what of the elves? How many acres were given over in these lands to food production/procurement, and how many were required to keep a dwarf on its feet all day?
...
So why were
prehistoric bugs so big (imagine a bug with a wing span of over two feet/70 cm!)? It's speculated that, with an atmospheric oxygen concentration up to 35 percent, bugs could be bigger back then. Did you know that bugs breathe through tiny holes and tubes and sacs that passively or actively get the air inside the bug? This ventilation mechanism limits the size of the bug - too big, and oxygen can't get to those cells deep inside the bug, those cells die and then...We, in case you haven't noticed, use our lungs and heart to circulate the oxygen around - and to rid ourselves of carbon dioxide, the same thing those bugs have to do.
What does this have to do with dwarves?
I've been wondering just how far away from an air source they can tunnel before they no longer can get air. Sure, Gandalf and company note air holes in Moria when they are camped outside the Chamber of Mazarbul, but what of the Mines? As with the
Romans, surely the dwarves encountered the ventilation and heat issues that plague miners even today. Toxic gases can be released when mining, water has to be diverted to somewhere, and when they lit fires in the upper chambers, you end up with chimneys sucking out the air from below.
Deep they delved them.
So, that said, did the dwarves, seemingly with scant food resources and possibly low oxygen concentrations, have the ability to 'live on less?'