Fahrenheit originally had the freezing point of water at 30 degrees, and body temperature at 90 degrees (can't get much more humanistic than that :-)).

Then he fudged the scale to 32 and 96, so there would be 64 intervals between the two. Probably no one here needs to have it explained why 64 equal intervals was a convenient number for the task of marking the thermometer (compass and straight edge would be enough).

Unfortunately it turned out that his number for the average body temperature was a little bit off. So it goes...