I note that there is no definitive answer, but there are interesting research moments pending.

I’m reminded of my biochem class where the doctor stated he knew of a research where they took an African who had known lack of lactase and provided one cup of milk.  That meant the bacteria in the fellow’s gut would start working.  The researchers then collected and divided by type the gasses eminating from this volunteer.  After the description, the prof says to the class, “See what you get to do if you become a biochemist?”  He then pretended to be the count from Sesame Street and count the….