During famines, why do most people seem to sit there and simply starve to death, rather than hunt, forage or darker still, kill and eat each other?

This is partly prompted by a medieval TV show I'm watching but also I remember seeing the famines in Africa on TV as a kid. People seem to just sit there and starve to death. Why not go out and start hunting wild animals or go into the forest/jungle and forage? Or failing that, kill your neighbours or strangers to feed yourself or your family? People, even mothers with children, just seem to sit there starving and I don't get it. I'd be doing whatever I could to ensure my and my family's survival.