What are the origins of sweet wines? Evolutionary biologists tell us that our distant hominin ancestors came down from the trees already addicted to the sweet taste of ripe fruit. Grapes, having the highest load of sugars of any fruit were thus instantly attractive to our protoselves wherever we found them.
What a thrill when we first learned that those sugars would spontaneously ferment, engendering that marvelous, mood-altering substance alcohol. Hurrah!
Now imagine the disappointment which must have followed when we realized the cost. All that dreamy sweetness that attracted us to grapes in the first place was used up in making ethanol. Boo! Hiss!