Troglodyte

Noun

1. A member of a supposed prehistoric race that lived in caves or holes, a caveman.
2. Anything that lives underground.

   "The cave was populated by albino scorpions, blind salamanders, and other troglodytes."

3. The Eurasian wren, Troglodytes troglodytes.
4. A reclusive, reactionary or out-of-date person, especially if brutish.
5. A person who chooses not to keep up to date with the latest software and hardware.