During the Paleolithic age, 400,000 – 100,000, years ago, early man did have fire available through natural sources. They would maintain some fire for their use, but it was not until the beginning of the Neolithic age, 100,000 years ago, that man actually controlled fire. He would start and control fire by rubbing two rocks together. There is much archaeological evidence supporting these thoughts.
Well, something else began showing up around 100,000 years ago – remains of early pipes and bongs!! So, it appears that as soon as man was able to control fire, he started smoking weed.