Once a race of technologically advanced humans, their homeworld Altair was destroyed by a violent and deadly form of radiation, forcing the survivors into underground maintenance facilities. As their bodies broke down, they developed the technology to transfer their consciousnesses into artificial, android-like bodies, identical in external appearance to the previous form. When SG-1 arrived they found one such individual, Harlan, to be the sole remaining survivor of the Altairan civilization.
After living beneath the surface for an untold number of years, several of the remaining survivors climbed up to the surface and walked beyond the radius of the energy source that sustained them, ending their lives. Wallace was the last to go, leaving Harlan the only one remaining. Harlan is determined to carry on the heritage of his people, and bears the brunt of the responsibilities for maintaining the underground structure for thousands of years to come.
Tin Man - With the arrival of SG-1, Harlan of Altair believes he has found the help he needs to carry on the facilities and creates android duplicates of the team.