From a reader:
Dear Mr. Goldberg
Just as a to add on to a previous posting about Ramadan, the Islamic calendar, while lunar like the Jewish calendar, doesn’t make any attempt to reconcile itself to the solar calendar. While an extra month is added seven out of every nineteen years to the Jewish calendar, the Islamic calendar just starts about ten days earlier (according to the Gregorian calendar) every year. Ramadan can therefore occur in any season, making for longer fasting periods in the summer. Not that this argues against your point at all, but those summer fasts must be pretty awful, regardless of latitude.