here is a link to a very recent article about when humans started wearing shoes. and some pros and cons about the cause/effect of wearing shoes. http://scienceblogs.com/afarensis/2006/04/16/when_did_humans_start_wearing/
I really wish society would give people the option to wear shoes or not. If people wanna protect their feet that ought to be their choice and if they dont then it should be their own problem if they get hurt because noone makes them take their shoes off.