In ancient days a dwarf is said to have stolen fire from the gods, upon which the gods decreed that they could keep the fire, but lose the gods. This is said to explain their habit of ancestor-worship, and skill in metal-working.
My enquiries into the truth of this story, and others, has borne little fruit. However I remain convinced that the dwarves' body shape indicates that they were designed, or evolved, for a higher gravity than exists on Teleleli or Earth.
It might be thought that the dwarves, being prodigious minders and builders of underground cities, would be constantly tunneling into the underworld. The reason why they have not been driven extinct in this fashion is the mineral they call 'Giant's Blood'. It appears in dark veins through certain rocks. Where it appears, it alerts the dwarves that danger lies on the other side. And in any case, it renders the rock almost impossible to break.