10 MORE Oldest Characters In The Star Trek Universe

Hodin and Odona were native to the planet Gideon. Theirs is a special case. Technically, they are not immortal, but the planet's lack of germs in its atmosphere allowed its inhabitants to develop certain abilities. These included the power to continually regenerate their cells, allowing them to greatly expand what would be considered a normal human lifespan.

This had the unexpected consequence of massive overpopulation on Gideon. It also led to a complete lack of medical personnel, as they were simply not needed.

The Gideon Council conceived a plan to effectively poison their population, introducing antibodies from foreign visitors into the local populace. This, it was hoped, would effectively cull a large portion of the people, thus reducing the strain on resources.

Though Odona is selected as a guinea pig, she is cured of the Vegan choriomeningitus she contracts from Kirk. There really is no resolution to the issue of overpopulation on Gideon by the episode's end, which is one of the stranger elements of the story. As it stands, Gideon may simply collapse under the weight of its population at one point.