Didn't they eat the hearts?
Hearts and liver....
The liver is where the fighting spirit resided.
The heart is where the soul resided.
To eat the heart and liver was to conquer the enemy and condemn him and rob him of spirtual rest (according to their beliefs, possibly reincarnation, a varied belief).
Jeremiah Johnson, of Wyoming/Montana? territory, was called "liver eat Johnson" because the Flat Head Indians held the belief that eating the liver of the enemy gave one the fighting spirit of the enemy. This was a widely held belief...(This is from memory, hopefully, I did not mix the Black Feet or Crow with the Flat Heads...)