Humans had a sophisticated calendrical system thousands of years earlier than previously thought, according to new research. The discovery is based on a detailed analysis of data from an archaeological site at Crathes Castle (Aberdeenshire, Scotland) - a row of ancient pits which archaeologists believe is the world's oldest calendar.
     The pit alignment, at Warren Field, was first excavated in 2004 - now a team led by the University of Birmingham suggests the ancient monument was created by hunter-gatherers about 10,000 years ago. Archaeologists believe that the complex of pits was designed to represent the months of the year and the lunar phases of the month. They believe it also allowed the observation of the mid-winter sunrise so that the lunar calendar could be annually re-calibrated to bring it back into line with the solar year.
     Remarkably the monument was in use for some 4,000 years and the pits were periodically re-cut over those four millennia. It is therefore impossible to know whether or not they originally held timber posts or standing stones after they were first dug 10,000 years ago. However variations in the depths of the pits suggest that the arc had a complex design - with each lunar month potentially divided into three roughly ten day 'weeks' - representing the waxing moon, the gibbous/full moon and the waning moon.
     The  50 metre long row of 12 main pits was arranged as an arc facing a v-shaped dip in the horizon out of which the sun rose on mid-winter's day. There are 12.37 lunar  cycles (lunar months) in a solar year - and the archaeologists believe that each pit represented a particular month, with the entire arc representing a year.
     The 12 pits may also have played a second role by representing the lunar month. Mirroring the phases of the moon, the waxing and the waning of which takes 29 and half days, the succession of pits, arranged in a shallow arc (perhaps symbolizing the movement of the moon across the sky), starts small and shallow at one end, grows  in diameter and depth towards the middle of the arc and then wanes in size at the other end.
     In its role as an annual calendar (covering 12 months - one for each pit), a pattern of alternating pit depths suggests that adjacent months may have been paired in some way, potentially reflecting some sort of dualistic cosmological belief system, not previously detected archaeologically from the Stone Age.
     "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," said Vince Gaffney, Professor of Landscape Archaeology at Birmingham, who led the analysis project
     Dr Richard Bates, of the University of St Andrews, said: "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 Field was constructed."
     The Warren Field site was first discovered as unusual crop marks spotted from the air by the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS). NTS archaeologist Dr Shannon Fraser said: "This is a remarkable monument, which is so far unique in Britain. Our excavations revealed a fascinating glimpse into the cultural lives of people some 10,000 years ago - and now this latest discovery further enriches our understanding of their relationship with time and the heavens."

Edited from BBC News, The Independent (15 July 2013)