I'm posting this in a number of different beer & homebrewing forums in hopes of hearing some different perspectives. I teach an "introduction to beer" class through a wine academy in DC, and I had a student ask me a rather interesting question last night that I was at a loss to answer. She was curious as to why beer was carbonated--not how it was carbonated, but the history behind why beer is carbonated where wine (with the exception of champagne and other sparkling wines obviously) and other alcoholic beverages are not. After some googling, I haven't come up with an answer. It's the first time I haven't been able to answer a question on the spot, so I want to find out the history for future classes. Any ideas?