"The women ran into the forest, and the men all got killed. Then the women came back out of the forest after the raiders had gone and buried their dead."
The new study suggests the period between 3625 B.C. and 3590 B.C. was one of "increasing social tension and upheaval," the team said.
This is in stark contrast to the traditional view, which sees Britain's Late Stone Age as relatively stable and settled.
"It was previously thought to be a time when there was plenty of land to go around, and that it was a very egalitarian society with little competition," Bayliss said.
"Maybe there was more competition between groups than previously appreciated."
The team's dating analysis also indicated that Neolithic burial mounds, known as long barrows, weren't in use for centuries, as originally believed, but only for one to four generations.
Furthermore, burials at the four long barrows surveyed appear to have ceased at about the same time.
"It's obviously a period of big change," Bayliss said.
The study also revealed big differences in burial customs, even between contemporary sites less than 20 miles (32 kilometers) apart.
The researchers discovered that one of the long barrows featured a wooden burial chamber that had been burned to the ground after use. Another had had its entrances blocked with stones.
At yet another site, Bayliss said, people had apparently returned to put animal offerings in the tombs of their ancestors.
"It's as if the immediate descendants of the people who are buried are going back and remembering them," she said.
"People seem to be doing things differently, even within a particular time horizon, which we've been able to estimate quite precisely," said team member Alasdair Whittle of Cardiff University in Wales.
Dating techniques used in the study combined radiocarbon analysis with a statistical method that takes into account other evidence, such as knowledge about ancient artifacts and the soil layers in which they're found.
Until now, Whittle said, archaeologists had tended to interpret changes seen in prehistoric customs and remains as a relatively smooth progression over time.
The new study presents a dramatically different picture.
"I'm sure we'll get more of these kinds of insights in future," Whittle added.
Free Email News Updates
Best Online Newsletter, 2006 Codie Awards
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES