So we all know that the primary way to win a wrestling match (in freestyle, Greco, and folkstyle) is to pin your opponent's shoulders or shoulder blades to the mat for 1 or 2 seconds (a.k.a. the fall; the pin; or if you really want to go back far enough, the pin-fall). Duh.
My question is: in the history of wrestling, how did that particular way of winning, the pin-fall, emerge as the prime victory condition in Western (particularly American folkstyle) amateur wrestling?
I know that in many European (and some Asian) styles, you could simply get your opponent to fall to the ground on any body part besides his feet, or get your opponent's two hips and a shoulder, or two shoulders and a hip to fall to the ground, etc., and that would be it. In judo, a pinning hold also scores a win, but the opponent has to be held down for 25 seconds, and they also allow submission wins. Other wrestling styles, seem to allow a win by submission, and real Greek and Roman wrestling didn't seem to have the pin-fall as a way to win.
Of course, there was also the touch-fall (closely related to the pin-fall, but not quite the same), that was prominent in the early days of Olympic-style wrestling.
It doesn't seem that the pin-fall emerged as a victory condition until the late 19th-century/early 20th-century at the earliest, am I wrong? If I'm right, why did the Western wrestling tradition choose/invent this way to win for wrestling above all the others that were common?
1) Did the pin-fall emerge out of battle tactics, ground fighting, early professional wrestling, or even judo? I mean if we're talking about battle tactics or ground fighting, a submission by armbar/triangle choke would probably be a better way to disable an opponent, than simply sticking his shoulders/scapulae to the ground.
2) Did people decide that the pin-fall would cater to wrestlers of all sorts of folk styles when organized amateur wrestling emerged on the world scene in the late 19th century/early 20th century?
3) Was the pin-fall more "humane" than other ways of winning (e.g. someone getting choked out in submission wrestling today)?
Thanks in advance for reading and considering all of this neophyte's questions.