As told by this article, the Burke and Wills expedition in Australia encountered friendly aboriginals who shared with them a grain called nardoo which they ritually prepared. The preparation was convoluted, with many steps which seemed superfluous. After relations broke down, the party attempted to prepare and consume the nardoo as they had observed but quickly succumbed to illness and death.
It turns out that nardoo is extremely toxic without being processed in a very specific way. To Burke and Wills this process looked like a religious ritual. Perhaps many of the steps in the preparation were pointless, but the superstition of the aboriginals in doing it exactly this way was vital because a small change in the process could lead to illness.
We definitely still see this sort of superstition in Western cooking today, Adam Ragusea does a lot of fun mythbusting in this area.