Been reading the book 'The Clan Of The Cave Bear' recently. A fictional story loosely based on history and it got me to thinking how much shunning is really a modern version of the death curse used back then. If someone was caught breaking the rules the curse would be carried out by the clan member in charge of their magicial/spiritual needs and as soon as it was carried out the victim would be regarded as dead. The other members usually believed the victim really was dead and just a spirit pleading with them to be allowed back into the clan... a very evil and deceptive spirit that knew how to 'push their buttons' so to speak. The victim was usually faced with watching their former clan members destroy their possesions and then left to face the world alone where they usually died from starvation, exposure or a predator.
The clan carried these curses out from the fear that allowing that member to continue on with them would bring bad luck from the Gods... that it was necessary for their survival... interesting read.