A humanoid people sharing a planet with the Valakians, whose potential to evolve shaped Phlox's decision not to give the Valakians a genetic cure.
The Menk are humanoids who share their homeworld with the more technologically advanced Valakians, who employ them in a subordinate position.
In Dear Doctor, the Valakians were dying of a genetic disorder and asked Enterprise NX-01 for help. Phlox found that the Menk appeared to be on the edge of their own evolutionary rise and argued that curing the Valakians would interfere with that natural course. Jonathan Archer agreed, and they provided only a treatment for the symptoms rather than a cure.