Archaeologists Solve Mystery of 5,600-Year-Old Skull Found in Italian Cave
smithsonianmag.com
smithsonianmag.com
De-fleshing for ritual might not be distinguishable from de-fleshing for food. Except, maybe food would show signs of heating because, 5000 years ago I think they had fire, and fire makes protein yummy.
Lots of cultures in time past (and present?) leave bodies and then collect the bones, clean them up, do ritualised things with them. I think fewer cultures eat their dead, its not unknown, its less common.
I'm not an archeologist. This is just my opinion.