Atkyan

The s were natives of the planet Atkya. They were humanoid but had scales.

The Atkyans suffered from renepscia syndrome, which was killing them. The Fifth Doctor and Vislor Turlough cured the syndrome, but at the cost of giving the Atkyans a higher metabolism, causing each generation to live half as long as the previous one. The planet was eventually deserted when the Atkyans died out. (PROSE: One Step Forward, Two Steps Back)