14 DAY TRIAL // In the 1960s, archaeologists found the remains of 14 people at Wayland's Smithy, near Uffington White Horse, Oxfordshire.
The bones were dated employing the latest technique at between 3590 - 3560 BC, and many clues made experts imagine that the people may have been killed in a Neolithic ("The Last Stone") Age massacre.
The diggings were carried out by English Heritage with the help of Cardiff University and the University of Central Lancashire.
"The findings suggest the Neolithic Age was more violent than previously thought. The victims - three of them probably killed by arrows - could have died in a rush for land or livestock," said Michael Wysocki of the University of Central Lancashire.
"We know one person was shot through the lower abdomen because we have found the tiny tip of a flint arrowhead embedded in their pelvic bone. We also know that the bodies of two people were scavenged and partially dismembered by dogs or wolves before their remains were buried in the monument."
"All this new evidence suggests that the period between 3625 BC and 3590 BC may have been one of increasing social tension and upheaval."
These people were not Celts (they entered Britain later) but perhaps closer to today's Basque people.
The new research also points that the Neolithic long barrows were short-lived and did not occur over hundreds of years as previously believed.
"With this research, we can now think about the Neolithic period in terms of individuals and communities and make useful and revealing comparisons between their choices and behavior in the remote past. This dating program demands a revolution in our thinking about prehistory and not just that of early Neolithic burial monuments in southern Britain," said English Heritage radiocarbon dating expert Alex Bayliss.