Yeah, yeah -- we all know about the 1846 expedition of pioneers that got stuck in the mountains and resorted to eating the corpses of those who died. But no mention of survival cannibalism would be complete without digging into the story of the Donner Party (pun!).
The Donner Party wasn't going swimmingly before being holed up in the mountains. They took a really crummy route to get West -- where they literally had to break ground for the wagon trail as they went, at one point -- and were caught in a desert for 80 miles (129 kilometers) before even getting to the point of no return in the California-Nevada mountains by November 1846.
They ate the pack animals first and then their dogs. After that they desperately made a gluey soup made from boiled animal bone and hide. By Christmas, the pioneers were eating those who had died, and there were several accusations among the group that people were being killed (or at least being neglected) so flesh would, ahem, be at hand [source: Diamond].
Now let's turn to another case of cannibalism, a more modern story of last resort for desperate travelers.