Oh, and your comment,
"So why do we get fearful of something like public speaking? Public speaking does not threaten our life at all, but some of the most intense fear comes from people who are speaking to the public. ...."
Public speaking requires group approval. There's always the chance - the threat - that one's presentation will result in group censure or worse yet, group apathy...
Apparently most people don't realize this, but "group approval" was essential for human survival during most of humanity's evolution. A human cast off by his/her tribal group became instantly vulnerable to lions, leopards, crocodiles, cheetahs, hyeanas, baboons, and so on...
There's always been strength in numbers... And I cannot emphasize this enough - humanity has ALWAYS been a species of HERD/PACK/POD animals. That "Marlboro Man" mythology is just that - a huge myth. Human beings nearly always were safer in a group - ESPECIALLY for the first hundred thousand years of our species' existence...
That behavior pattern - vulnerability, if you will - is exactly what made excommunication - expulsion - exile - such an effective means of discipline. It's really a type of living death, given humanity's need for companionship - a yearning to be with familiar other humans, which was originally based upon the need to be part of the "herd" in order to survive...
And that is EXACTLY why shunning is such a vicious, yet effective, method of discipline/abuse...
Zid