University of Birmingham researchers believe to have found the world's oldest 'calendar' during an excavation in Aberdeenshire, Scotland.

A series of 12 pits dug out at Warren Field at Crathes Castle in Aberdeenshire, Scotland appears to follow the phases of the moon to create a primitive calendar. The ancient calendar is claimed to be created and used by hunter-gatherers to track lunar months.

Teams from the universities of Birmingham, St Andrews, Leicester and Bradford, state that each pit appears to represent a month.

Vince Gaffney, professor of landscape archaeology at the University of Birmingham led the project.

"'The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year and that this occurred nearly 5,000 years before the first formal calendars known in the near east," Gaffney said.

"In doing so, this illustrates one important step towards the formal construction of time and therefore history itself."

Until this discovery, the first formal time-measuring devices were predicted to have been found in Mesopotamia, about 5,000 years ago. But the experts said that the pit alignment near Crathes Castle dates back 10,000 years. The monument was used for some 4,000 years from around 8,000 BC to around 4,000 BC.

The Mesolithic monument was actually excavated at Warren Field between 2004 and 2006 and was recently analysed by Birmingham researchers.

Clive Ruggles, emeritus professor of archaeoastronomy at the University of Leicester, served as an adviser to Gaffney's team.

Ruggles said that the primitive calendar was meant to serve as a time guide to Mesolithic societies to help them plan various activities throughout the day; to predict seasons and to keep track of animal migrations to ensure their survival.

Dr Richard Bates from the University of St Andrews, was also part of the project and said that the pit monument provides new insights into the 'sophistication' of societies in early Mesolithic Scotland.

'This is the earliest example of such a structure and there is no known comparable site in Britain or Europe for several thousands of years after the monument at Warren Fields was constructed."

Before the university researchers could lay their hands on the pit, the site was first discovered when odd crop markings were observed during an aerial survey by the Royal Commission on the Ancient and Historical Monuments of Scotland.