If you were hungry enough, would you eat your deceased friend? It seems unimaginable, yet that is the situation facing the survivors of the plane that crashed in the Andes in the article.
At first, the survivors really do not like the idea of eating their fallen comrades (who would?). It is a very obvious norm in most all societies that we do not eat one another. It is a pretty simple rule to follow, unless the situation demands it. In the situation of the survivors, they are facing death, as they are starving and well aware that rescue is unlikely. Norms are powerful but will be circumnavigated when it is absolutely necessary. And in doing so, structure and new norms are created (they develop rationing for the eating). And eventually, their old norms are irrelevant and new norms govern their lifestyles.
Basically, norms are all relative. Things in our lives have meaning because we give them meaning. In a subtle way, the article is showing that we should not judge the norms of other cultures, because we often do not know the circumstances that cause such norms.
I, for example, have a different set of norms acting upon me than say, a man in China. What I gesture for "OK" means something much more derogatory to the Chinese man. Both of us, being unaware of each other's norms, would be confused by one another.
To test your knowledge of norms, here it is... the one, the only, the URINAL QUIZ GAME!