I'm gonna say beer. That might seem odd but there's actually a good reason for it.
Apparently archeologists discovered that early man found a way to make alcoholic beverages and they started to theorise that they came up with ideas like the wheel and cities because they were drunk.
Ug: "Hey Og? (hic) You know whut... You know whut would be really funny?"
Og: "Ug, have you been drinking again? Deary me you have a problem and need help."
Ug: (hic) We shud get a rock... And and and... An' we shud, like, make it all (hic) round and stuff."
Og: "And why, pray tell, would we do that?"
Ug: "I 'unno (hic). Be funny wudn' it? We cud like, roll it around an'... An' other stuffs like rolling it around... (burp)"
So I throw my vote in for beer which very well may have been the root of mankind's technological advancement.