User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-4003956-20120423163831/@comment-1653324-20120424150532

The higher oxygen also explains fire wyvern fluid. When Raths spit it out, the Rath's own body heat and greater concentrations of oxygen (compared to inside its body) causes the fluid to ignite into fireballs.

The low gravity thing and the fireballs don't really mix. Lower gravity means a thinner atmosphere. The thinner atmosphere implies less atmospheric pressure. Taking into note, an astronaut on the moon would still have difficulty lifting stuff (not because of the suit). That's just 1/6 the Earth's gravity. 1/6 our gravity, and the moon doesn't even have an atmosphere.

Biology-wise, monsters would evolve according to their surroundings. There are animals that developed in the bottom of the oceans with great pressure (I know, pressure is not gravity), and actually can't live without it.

The sonicwave-sand theory is a very solid argument coughlamepuncough. Soft ground doesn't really sound that good. Jinouga stomps at the ground and proves it's solid, and the sand is hard enough for Copper Blangonga to throw. No problems with lava creatures though.

A good counter I thought of, inspired by the oxygen theory, is that the air in MH is denser. The increased drag causes falls to accelerate at a lesser rate. Denser air also allows creatures with relatively small wingspans to fly. It also explains wind effects easier too. If localized wind was that strong, surely it would cause eddies and whirls to linger around. With denser air, wind doesn't need to be that fast to cause us to stagger. A counter to this is that "denser air is like walking in a pool, it's difficult". Yes, air is a fluid, and shares many traits with water. But, unlike water, it is a gas. It's not that dense to actually hamper our regular movements (the space between molecules is large/indefinite).

Sorry for the mulitple walls of text