Ocampa

The Ocampa are a species of humanoid sapients native to the Delta Quadrant. They are notable for having abnormally short lifespan, telepathic abilities, and -- despite reproducing sexually -- giving birth only once in their lifetime. There are two known populations of this species, the largest of which is in all likelihood extinct by now.

Evolutionary Stupidity

The Ocampa are perhaps the most unfit-to-live species ever devised in Star Trek.

• They have a life expectancy of less than 20 years (at best, most live less than 10 years).
• They only mate to produce children once in their lives.
• A typical mating only produces one child.

By this idiotic math, each Ocampa generation is no more than half the size of the previous one, which means they're rushing toward extinction at ludicrous speed. In reality, nature would never produce a species with such absurd reproductive characteristics.