> Air-conditioning is not even a hundred years old and was originally not even invented to keep people cool (it was invented to keep machines from overheating).

Nitpick, you're close but according to Wikipedia:

"In 1901, American inventor Willis H. Carrier built what is considered the first modern electrical air conditioning unit. In 1902, he installed his first air-conditioning system, in the Sackett-Wilhelms Lithographing & Publishing Company in Brooklyn, New York; his invention controlled both the temperature and also the humidity which helped maintain consistent paper dimensions and ink alignment at the printing plant."