Many ethnographic accounts suggest that built-in psychic entropy is more common in preliterate cultures than the myth of the noble savage would suggest.
While all those types of information were also transmitted by other means in preliterate societies, writing made the transmission easier, more detailed, more accurate, and more persuasive.
The myth of the happy savage is based on the observation that when free of external threats, preliterate people often display a serenity that seems enviable to the visitor from more differentiated cultures.