But more recent skulls, dated to 200 to 400AD, showed signs they have been severed, indicating human sacrifice took place in the caves.
It is believed as part of a funerary process bodies were not burned or buried, but laid out in the cave to decay, as it was remote enough to protect the rotting corpses from wild animals and birds.
Mr Armit added: "But complete bodies were not left to remain.
Skulls, and long bone fragments like arms and legs were hugely under represented among the bones.""Certain parts were removed and you can start to see some sort of complex burial and funerary process that is very rarely seen as part of archaeology."They have managed to conclude they have the parts of a minimum of 28 individual people's bones from Sculptor's Cave - but probably "a much larger number were buried there"Mr Armit said: "In the entrance passage were bones from heads, mandibles and crania, all which belonged to young individuals aged from two."There were eight or nine remains of children's heads and also pieces of hair rings."We believe they would have been there for some sort of display of human remains at the entrance passage to the cave."So you would have preserved human heads with finery hair rings displayed at the entrance disintegrating."Quite a disturbing and striking image.
The mandibles had probably rotted off and fallen where they were."But the scientists found no evidence of violence, in the case of these children, and believe the macabre body mutilation would have been seen as a sign of reverence.
Mr Armit said: "There is no evidence of violence in the late bronze-age material - no suggestion this was head hunting or trophy taking."They were letting dead the dead decay to be absorbed back to the earth and removing some bones for other purposes."It is a very, very alien kind of treatment of the dead we are not used to or comfortable with, but it is confirmed with other ethnographic discoveries."On the floor of the entrance passage there were a lot of stake holes.""One possibility is the entrance was blocked and bodies protected, sealed off from the outside world, or it was the footing of some form of structure on which the bodies were allowed to decay."Some of the child skulls had abrasion marks - a sign they may have been polished - as part of the display Mr Armit said: "In the late Bronze Age it was a secondary funerary treatment seen as reverential and caring and intended to facilitate transition from life into death."The cave was obviously a natural place to act as a conduit between the living and dead."Example of bodies dated to between 200 and 400AD - the Roman Iron Age - have also been found, which suggest a much more sinister use in later years.
Among a haul of tweezers, coins fake Roman coins from the time, and hair pins, thought to have been deliberately left as offerings to Gods, were remains of six decapitated people.
Mr Armit said: "The cervical vertebra upper bone in the necks of all of them have got cut marks indicating decapitation."Six individuals had their heads violently removed in the cave itself."Unless the individual bodies were brought to the cave, it is more likely, these individuals were executed in the cave."They possibly died at once and it may have been an event."By the consistent way it was done, with, in some cases 11 cut marks in each vertebrae, it indicates a brutal and deliberate act."All were attacked in the same way - assaulted from behind with their chin held down to the chest, so more than one person was involved in their execution."In a cave that already has more than 1,000 years of funerary activity, it could have been a sacrifice, not just military or political.
It was heavily ritualised and potentially witnessed by a great many people."Sculptor's Cave was investigated in the 1920s, when several bones were removed, and later in the 1970s, but this is the first time any have been radiocarbon dated.
The macabre shrines to the dead were based at the remote site at Moray Firth in north-eastern Scotland.
Human sacrifices are also said to have taken place at the caves, which are so cut off they can only be accessed from land at low tide or by climbing down a sheer cliff face.
New evidence also suggests the caverns, which have stone carvings of leaping salmon, broken spears and other symbols of the Celtic Pict tribe, may have been in constant use from as long ago as Neolithic times.