Lart was the youngest son of the neanderthal Ne-Ahn. His older brother was Anthro, the "first boy on Earth." Lart looked up to his younger brother, and often accompanied him on hunts.
During a hunt with his father, Anthro brought down a woolly mammoth. When Anthro returned with Lart to retrieve the body, they found the area prowled by scavengers. While Anthro was distracted, a pack of wolves led by a 16 foot long wolf named the Great Kano attacked. He and his pack were after the dead body of the woolly mammoth, and would not let Lart stand in his way. Lart defended the body with his spear, and both the combined attack of Lart and Anthro killed him, but the Great Kano came down on Lart's leg, crushing it.
Anthro rushed Lart back to the family cave, where his mother-in-law Emba healed him. However, Lart's leg would never work again. Anthro crafted Lart a crutch, and even with his disability, Lart would still accompany Anthro on his hunting trips.
While on one such exploration, Lart and the family discovered the lost city of Katara. When they arrived, they were welcomed as kings, especially Lart. Evidently, a prophecy foretold of a bonde-haired one-legged child would come to rule them. Lart became ruler, but the old queen wanted to still run things. She tried to manipulate Anthro using her charms, but the family discovered her schemes. She ordered their deaths, and the family was forced to flee.