The house I grew up in was built in 1863, and had a small outbuilding that had been the "summer kitchen." I think the concept is pretty similar to grilling so that the house doesn't heat up. The house next door had a cold cellar -- a great hiding place for us when we were kids!
We do not have ac...... and I honestly don't want it, although DH would probably be happier if we got a window unit or two. I do a lot of what has been mentioned in other posts in regards to keeping crossbreezes going, keeping the blinds down during the day and the windows wide open at night. I keep cooking to a minimum and do it all early in the morning. I do as much housework and yardwork as possible before noon. It's 94 degrees here (and climbing), and DS and I have been out working in the garden, and DD is out riding her bike right now...... I think that it doesn't phase us because we are used to it, but that DH has more of a problem after spending the day in an office with ac.