自然 しぜん発生 はっせいじゃなかったです
shizenhasseijanakattadesu

Noun
Desu Copula
no-Adjective

The polite, past negative form of 自然発生

1. It wasn't natural.; It didn't happen naturally.; It wasn't spontaneous.

Past/Perfective
Negative
Polite
Casual Register
Biology