In speculative fiction settings with very high technological levels, older Space Opera in particular, transhumans, meaning people who use cybernetic and/or genetic enhancements to give themselves capabilities far in excess of those of ordinary humans, will often be either completely absent or much rarer than you would expect given the stated capabilities of the society they live in. In the older works this was more a case of No Transhumanism Existing As A Distinct Concept Yet, though they did have Evolutionary Levels and/or Mutants which often served the same plot purpose. A primary contributor to Schizo-Tech.