I read about this ill-fated expedition in Natl Geo a few years back. One of the main reasons the expedition was even possible was because canned food was a new process back then. They went off their noggins with the lead poisoning; the Natives thought they were insane when they brushed paths with them and stayed far enough away to avoid contact. Some mummified remains had been found in the late 80s.

https://www.youtube.com/watch?v=89Bwy-Pz7JI       55 minutes.