I remember first reading of this phenomenon from Rojo-Guerra et al, 2015. The Rojo paper really started poking at something that may not have been so obvious in the past. It appears bodiless graves are everywhere throughout the beako-sphere and quite common - they may include a smashed pot or two, a solitary bead from a necklace, a single arrowhead, maybe a dagger or two or three, other 'part' artifacts, like animal parts.
Some are near graveyards. Many are just out there (apparently). They're everywhere: NE Poland, Czech, Britain, etc, etc.
|"So I've got this problem..."
A bothros was a pit dug by early Greeks for summoning a dead person from the underworld. Beer, wine, sacrifical blood and personal artifacts are used to conjure the spirit of a dead person, and then like Ulysses or Saul, prepare for the best advice ever.
Here's how they are described in "The Sacrificial Rituals of Greek Hero-Cults in the Archaic to Early Helladic Period" by Gunnel Ekroth,
"More significant is the use of the bothros in magic rituals for direct contact with a particular dead person. In Lucian, for example, a young man has a magician dig a bothros and perform rites to summon his dead father and to make it possible for the son to hear his father’s opinion of his girl-friend.190 In the Aethiopica of Heliodoros, a mother performs an elaborate ritual at a bothros on the battlefield at night, to bring her fallen son back from the dead, so that she can inquire about the fate of her other son.191 By digging the bothros and sacrificing into it, a dead person or the divinity could be summoned and called up to the world of the living."After re-reading many passages by Ekroth and comparing his descriptions to some of these Beaker pits, I think we might be dealing with people that needed a lot of advice.