I don't think laziness accounts for that behavior. Need for efficiency and business might, since most inventions are motivated by yet other endeavors which hard

I don't think laziness accounts for that behavior. Need for efficiency and business might, since most inventions are motivated by yet other endeavors which hardly counts as lazy. I think that the most basic ideas involved in hunting, farming and fighting are motivated by the ultimate need to get some rest. OTOH, rest shouldn't be confused with laziness, which has a negative connotation, because some see idleness as an ill when it is assigned the highest priority before other desires/needs.