Hunters who were wounded or ill were left behind by compatriots who sealed them in caves to protect them from wild animals. When they recovered enough, they were supposed to push the stones away. Some didn't get better and became interesting archaeological finds with spears and other personal effects. Evidence of many of our contemporary customs appears at Neanderthal sites. At Iraq's Sharindar Cave, for example, flowers were left with a burial.
Personal effects accompany other burials.
Neanderthals also began the practice of carefully orienting the body on an East-West axis or so that the corpse faced east. If the hiding of the dead body was not, at first, a ritualized attempt to renew the deceased through planting, it was an early precursor of sedentariness. The first cities may have been cities of the dead, complexes of grave mounds whose walls were adapted to other purposes. We know that the Saxons, for one, used their burrowing skills to signify prestige. Dead men of great reputation were covered with more dirt than their lessers.