Because we know you were dying to know. This video features Piers Gibbon — a British explorer, author, and National Geographic TV show host — describing the head-shrinking process long performed by the Shuar people of Ecuador and Peru.
Below is a quick recap of the process, also provided by Gibbon, in a recent interview with the folks over at Life's Little Mysteries.
First stage, kill your enemy...and chop his head off, leaving a decent amount of neck flap underneath the head. Then, second stage — absolutely crucial — you need to crush and remove the human skull, so you break it up with rocks and pull it out of the neck and all of the brain matter and everything else. So you're left with, basically, a head bag.
This head bag is then boiled in water with, I think, herbs and spices added to tan it — like with leather — and that is effectively shrinking it in the same way you would shrink any leather if you boiled it.
And then, what you really need to do is get out all of the last little bits of fatty tissue from...say, around the lips. You need to get rid of that. And you use hot sand from the fire to get rid of those. So you push it into the head, and get rid of all the fatty tissue...and then pull that out.
Then, you have to sew up the eyes and the mouth so that the soul of your vanquished enemy cannot see you and cannot call for vengeance.
Then you have won.
Pretty gruesome. Also pretty awesome.