A team of British archaeology experts, including two from Bradford University, have discovered what they believe to be the world’s oldest ‘calendar’.

The Mesolithic monument, believed to have been created by hunter-gatherer societies and dating to 8,000 BC, is a series of 12 pits found in Aberdeenshire, Scotland, and predates the first time-measuring devices known to man by nearly 5,000 years.

Until now, the first formal calendars appear to have been created in Mesopotamia about 5,000 years ago.

The research team includes University of Bradford archaeological geophysicist Dr Chris Gaffney, and research assistant Tom Sparrow, who helped analyse the monument, which is at Warren Field, Crathes.

The team was led by Dr Gaffney’s brother, Professor Vince Gaffney from Birmingham University, in collaboration with colleagues from the Universities of Leicester and St Andrews as well as The Royal Commission on Ancient and Historical Monuments of Scotland.

They discovered that the 10,000 year-old monument appears to mimic the phases of the Moon in order to track lunar months over the course of a year.

However, there are on average 29.5 days in a lunar month, so a lunar year is about 354 days, 11 days shorter than the solar year at 365 days. This causes a problem because after about three years the lunar months are out of cycle with the solar year by about a month.

To correct this, the monument also lines up with the Midwinter Sunrise which occurs at the same time in the solar year, in order to maintain the link between the passage of time, indicated by the Moon, and the solar year and its associated seasons.

Mr Sparrow said: “The people that built the monument at Warren Field may not have understood why these cycles were different, but they clearly recognised this mismatch and were smart enough to find a way to simultaneously keep track of both and make a correction for the drift, ‘resetting’ the lunar cycle.

“Understanding the seasons was crucial for much later farming communities, to know when to sow and harvest crops throughout the year, but earlier communities were not really thought to have the same need.”

Dr Gaffney said: “In archaeology, our growing knowledge and understanding of the past can sometimes feel at odds with what’s seems to be logical. Nobody expected to see a calendar of this sort in this period.

“Many thought that pre-Neolithic people either wouldn’t need something as nuanced as this or that they wouldn’t know how to create such a thing.

“But resources for pre-historic hunter-gatherer communities were crucial. These people survived by hunting migrating animals and needed to carefully note the seasons to know exactly when to be ready and where to be when this food resource passed through, such as fish runs in nearby rivers, for example.

“The consequence of getting it wrong was potential starvation.

“From this perspective, our interpretation of this site as a seasonal calendar makes absolute sense.”

The research is published today in the journal Internet Archaeology.