People "know" how the snakes die by scientific exploration in how the bodies react to different stimulation and situations. The freezing info is in some studies somewhere. You could google up that. It's not hard to see a head that responds to movement and touch AFTER being seperated from the body completely, and understand that it can feel if it can respond to outside stimulius.
Foschi: And I've had to "put down" snakes and other pets in the past, thank you so much for assumptions that no one here has ever done the humane thing. This past year saw my cat of 24 years put to sleep at the vet, and more than one misformed hatchling killed instantly to prevent that "long suffering death". If you consider a disagreement a flame, then here's one for you.
I feel anything instant = humane. Doesn't matter if it's ugly or brutal looking... if it's instant for the animal, that's more important than if it's pretty to watch.