More Soda Ranting

When 7-11 introduced the Big Gulp back in 1980, it was  revolutionary because it was so big. You couldn’t get fountain drinks that big previously. Now they have a “Super Big Gulp” and a 'Double Gulp.” (The “regular” at Wendy’s.) Where did this come from? I don’t think the human stomach has grown in the last 30 years, at least not proportionally to the beverage sizes. Nor do I recall the 70s as being a time of general unrequited thirst. I don’t remember a single instance when I finished my can of pop and thought, “You know, I could really use another 24 ounces.” What changed? Is it just slick marketing? Global warming?