 Dwarves have an average lifespan of 250 years.Occasionally they would live up to 300 years of age, and Dwalin reached the rare lifespan of 340 years (comparable to a Middle Man living to 100).In "The Lord of the Rings" Tolkien writes that they breed slowly, for no more than a third of them are female, and not all marry; also, female Dwarves or Dwarf-women look and sound (and dress, if journeying—which is rare) so alike to Dwarf-males that other folk cannot distinguish them, and thus others wrongly believe Dwarves grow out of stone.