It's a complex function involving social and environment stressors which effect progression, and social and cultural context which effect manifestation, and there's also feedback between manifestation and progression.
I think it's widely accepted, albeit in a somewhat loose way, that the reason "schizophrenia" was not previously attested is because society explained the behaviors differently and often in less negative terms such that there was less positive feedback that negatively effected progression and manifestation. An archetypal example would be that someone who experienced hallucinations might be understood to be highly spiritual, a mystic, or just quirky. Moreover, people lived in more tightly knit family and social groups, so someone who had trouble taking care of themselves would be more likely to live with or near compassionate family members. And if someone did become a poorly kempt recluse, that didn't by itself turn them into complete social pariahs, so they could more easily have some minimal normative social relations. OTOH, if someone just completely fell apart and died from exposure, or antagonized the wrong person and was killed, the cause wouldn't have been attributed to a mental disease, per se.
And the effect of culture goes even deeper. Hallucinations among those living in modern, western societies tend to be more paranoid and violent; more likely to involve the threat of "the government" or "they" than, say, a beneficent god or playful tree fairy. Or more specifically, as seen in many recent anti-Asian assaults, acting out racial animus received from the culture. The increased negativity in hallucinations and behaviors feeds back into progression directly (more stress from the hallucinations) and indirectly (people are more afraid and wary of you, so you more quickly become separated from supportive social networks).
I think it's widely accepted, albeit in a somewhat loose way, that the reason "schizophrenia" was not previously attested is because society explained the behaviors differently and often in less negative terms such that there was less positive feedback that negatively effected progression and manifestation. An archetypal example would be that someone who experienced hallucinations might be understood to be highly spiritual, a mystic, or just quirky. Moreover, people lived in more tightly knit family and social groups, so someone who had trouble taking care of themselves would be more likely to live with or near compassionate family members. And if someone did become a poorly kempt recluse, that didn't by itself turn them into complete social pariahs, so they could more easily have some minimal normative social relations. OTOH, if someone just completely fell apart and died from exposure, or antagonized the wrong person and was killed, the cause wouldn't have been attributed to a mental disease, per se.
And the effect of culture goes even deeper. Hallucinations among those living in modern, western societies tend to be more paranoid and violent; more likely to involve the threat of "the government" or "they" than, say, a beneficent god or playful tree fairy. Or more specifically, as seen in many recent anti-Asian assaults, acting out racial animus received from the culture. The increased negativity in hallucinations and behaviors feeds back into progression directly (more stress from the hallucinations) and indirectly (people are more afraid and wary of you, so you more quickly become separated from supportive social networks).