I'm not saying food isn't necessary- it's just that "living off the land" is not an important skill to have to survive for 72 hours. Preventing hypothermia and attracting the attention of rescuers are at the top of my priority list. I have a couple power bars in my PSK, because a quick jolt of calories can do wonders to reverse a downward spiral into hypothermia. If the situation goes beyond a few hours, water is the next priority. Once I've got those needs taken care of, and rescue doesn't seem forthcoming, then I'm going to start worrying about feeding myself and my companions.