Just how far back, in human history, has there been evidence of people knowing ways of getting ‘high’, ‘buzzed’, and/or ‘drunk’?
I mean, is their even the posibilty of early man sampleing anything that was mood altering, mind altering, or stimulating?
Indeed. Some time back I read an article in the New York Times about a scholar who believed that early beer making was responsible for the advent of agriculture.
Links of interest:
Evidence of Ancient Beer
http://www.vegan-straight-edge.org.uk/GW_paper.htm :
“Though it was, we suggest, the presence of exorphins that caused cereals (and not an alternative already prevalent in the diet) to be the major early cultigens, this does not mean that cereals are ‘just drugs’. They have been staples for thousands of years, and clearly have nutritional value. However, treating cereals as ‘just food’ leads to difficulties in explaining why anyone bothered to cultivate them. The fact that overall health declined when they were incorporated into the diet suggests that their rapid, almost total replacement of other foods was due more to chemical reward than to nutritional reasons.”
According to Erowid, cannabis was used as medicine in China nearly five thousand years ago. I can’t imagine any medicinal use that wouldn’t get the patient high.
Just IMHO, I would imagine people got “high” as long as people have been around.
… Hey, somebody wake up Lotar, he’s been in the berry patch again …
… Grog, why don’t you do something useful with your life, like go hunting with the rest of the guys, instead of hanging out at the berry patch all day …
… Booka, pick me up a six pack of yellow berries and a pack of Chesterfields …
… Damn Motak, these are some kick ass berries, you have a kilo for sale? …
… Hmm, I wonder what would happen if I dried these berries and smoked them in a pipe? …
… That damn Sheenoo is nothing but a berry whore …
… hey ccwaterback, are those berries still legal? Can you get me some seeds? …
Hmmm…
Lest any of the more clueless among the teeming millions think I’m trying to score drugs here, let me just say right now that the above was 100% hyperbole. I forgot the smiley 
I don’t know how old the sources for the Biblical story of Noah’s flood are but it looks like drunkeness was part of life then.
After the flood subsided Noah planted a vinyard and got drunk on wine from the first crop.
Not just booze and grass, but 'shrooms too: there’s an assertion in The Sacred Mushroom and the Cross by John M. Allegro, that early Judaism and Christianity were influenced by psychoactive drugs. (Disclaimer: I read this years ago and it seemed fairly scholarly at the time, but I have no idea whether or not Mr. Allegro is a whacked out loon or a genuine theorist.)
Whether or not this is a valid assertion, since it’s known that other mammals seek out psychoactive substances (e.g. reindeer trip from, Amanita Muscaria toadstools [Jared Diamond, The Rise and Fall of the Third Chimpanzee]), so it’s a fair bet that our early ancestors would have gotten as high as they could from anything they could get their hands on.