During the European famines of the 13th and 14th century cannibalism was quite common. They had no choice, it was either kill someone and eat them, or die.
A few records and documents from the period indicate that people were able to receive absolution for doing it, which in those days meant 'priest waves a magic wand and says some words, poof, you aren't a criminal anymore'.
Cannibalism also happened during the Holodomor in the Ukraine, 1930s I think. Stalin decided that due to basic incompatibilities with the government and due to the fact that there were just to many of them to control, he froze ALL food and drink shipments of ALL kinds, both into, and out of, the Ukraine, with military officials having a monopoly on the food that remained there and given quite clear instructions not to give their food to ANY one on pain of either A, death by hanging, or B, life sentences in the gulags.
The soldiery's general behavior is summed up in the next sentence.
'Ehhh they'll be dead in a few hours anyway, its best we just go ahead and kill them. But remember Comrades, use your bayonets and hanging ropes, -don't waste bullets-.'
When the census numbers came back later that year Stalin eventually decided to end the blockade on all food and drink and allowed life to return to normality. I personally believe he did it to show them he could do anything he wanted to anyone any time he wanted to.
Cannibalism abounds in world literature as well. An example that immediately comes to mind is Ugolino and Ruggeri, in circle 9, canto thirty..... one, I think. Might be 30, dante's inferno.