The oldest tech you still use

[Umbran]

Fire good.

Fire bad. Tree pretty.

 

[Umbran]

fire

Oxygen-based metabolism.

Or, even older - DNA.

 

[Willie the Duck]

Oxygen-based metabolism.

Or, even older - DNA.

Atoms and photons.

 

[Lanefan]

Fire bad. Tree pretty.

"Tree bad. Fire pretty." - more D&D characters than I can count, including several of my own.