Megan McArdle participated in a panel discussion on fear with Chris somebody and Frank Furedi. The topic was fear, which I discussed here.
Furedi, a sociologist, complained that people are starting to have their identities wrapped up in what they fear. Several in the audience proceeded to prove him right--they were very attached to their fears of global warming or George Bush's police state.
Furedi has been thinking about this issue a long time, and it showed. The webcast is almost two hours, and I bailed out before the end, but I recommend at least watching Furedi's opening statement.
One of Megan's points is that we have only recently overcome the need to fear death from starvation. And I think that all of the panelists brought up various irrational fears, such as fear of witches.
If you think of it in terms of human evolution, it makes sense that we would be very alert to danger. What makes less sense is that our mechanisms for distinguishing real dangers from irrational fears would be so inadequate.