[masklinn]

> The case with the cake is even more mesmerizing, it slowly blocked overtime their ability to process B1. How could people tell that it was from that food??

Keep the information about ill effects as part of the cultural package alongside the prep rituals? That way you can kinda sorta notice that the ill effects still occur and cooks can try to add new preparation methods.

Alternatively, simple evolutionary process: cooks semi-randomly add new steps (whether because luck or opportunity), some tribes push back deadly effects further back and thus have better survival rates, leading to their preparation methods spreading. Nardoo occurs throughout Australia, so native populations would have tried using it for a very long time (tens of thousands of years).