A stone ball 20 feet in diameter may provide archaeologists with a vital clue as to the real reason for the construction of the Avebury Stone Circles and of Silbury Hill, Europe’s largest artificial mound.

The ball was found two months ago in a farmer’s field at the base of Silbury Hill and was believed to have been placed in a ceremonial pit. The ball is a boulder, probably an erratic from glacial times, that has been roughly hewn by masons to ensure that it moved in a straight line.

Three years ago, two skeletons were found at the base of Silbury Hill. What astonished their discoverers was that nearly every bone in the skeletons had been crushed. They were facing towards the hill and appeared to have had their arms stretched out in front of them, in what was believed at the time to be a kind of submissive gesture of prostration towards the sun god.

No-one knows why Silbury Hill was built, but the ball has given some people ideas. They think the hill was built to give the ball lots of impetus so it could knock down human bowling pins standing on the hill’s lower slopes. These targets would likely have been members of conquered tribes or poor farmers who didn’t grow enough crops for the local king’s liking.

Other less fanciful ideas suggest that the ball may have been used as a kind of divination, or “boulderomancy” as it has been termed. The ball would have determined who should farm an acreage of land, in times when there was a shortage of suitable fields due to population growth. This divination would have reduced the population too.

The gaming idea could well have been extended from human bowling to a Stone Age mixture of roulette and pinball. Scientists examining Silbury Hill believe there were plans to double its height so that the ball could have rolled all the way to the stone circles at Avebury. They also think that the ceremonial way of standing stones was actually built so that the ball wouldn’t deviate from its path towards the stone circles. The idea was that gamblers would place bets on which rock in the circle the ball would nestle against.

It’s thought that the rulers of the times had tired of continually battling each other for small pieces of land and had collectively decided that gambling was a far better way of deciding territorial disputes.

What would have caused the games to stop? Well the ruler who came up with the gambling idea may have died or indeed become a victim of the ball, which would explain why the graves at the nearby West Kennet Long Barrow are so narrow. The ruler may have known that he was dying and so he decided to be killed by the ball in an early form of euthanasia, which might be why the ball was given a ceremonial burial.