 If I was to ask you where the oldest calendar in the world was found, where would you say? Some may say some were exotic, like Babylon or Ancient Egypt. Others might say don't know, don't care. How many would say Scotland, however? Today I've come to Warren Field and Aberdeenshire, in the grounds of Cratus Castle, which is the site where the oldest calendar in the world was found. Dating back an astonishing 10,000 years to 8,000 BC, predates what was previously thought to have been the oldest calendar in the world by 5,000 years, a calendar that was found in Mesopotamia. The calendar is a series of 12 pits in the shape of a general arc that mimic the phases of the moon and track the lunar months. There are also three smaller, undated post holes adjacent to the central and largest pit, pit number five. This lunar calendar was also aligned with the midwinter sunrise, which worked to calibrate the calendar. Without this calibration, the lunar calendar would inevitably fall out of sync with the seasons, as a lunar calendar alone is not an accurate tracker of seasons without some correction. As Vince Gaffney, Professor of Landscape Archaeology at the University of Birmingham, along with his colleagues, writing Time and a Place, a Lunar Solar Time Recanner from 8th Millennium BC Scotland, published in Internet Archaeology in 2013. A key characteristic of using lunar phase cycles for calendrical purposes arises because the length of the seasonal year is not a whole number of lunar phase cycles. This means that a lack of correspondence with the seasons will inevitably ensue if the moon is used as the primary guide to the passing of time. Thus, the people who constructed this site must have had a deep understanding of the lunar phases, whilst also understanding the imperfect nature of the system and the need for calibration. The fact that these people 10,000 years ago understood both components is quite remarkable. It speaks to the fact that they and their ancestors must have tracked time for decades and centuries prior to its construction. Who were these people, however? It is thought that they were a group of hunter-gatherers that lived around this region of Aberdeenshire around 10,000 years ago. Considering that these people showed the sophistication to track time in such a way, there must have been an intelligent and sophisticated people. You would have probably thought that this site was constructed by a farming civilisation and the fact that it was constructed by hunter-gatherers is astonishing, indicating that hunter-gatherer societies were far more worldly and intelligent than is often assumed. It is believed that one of the primary reasons that these people constructed such a calendar was to track the seasonal migration patterns of animals to ensure that they had consistent feed sources and to plan for leaner seasons. Knowing where there was going to be an abundance of fish on the River Dee, for instance, which is just south of this site, would be one use for instance. The authors in Time and a Place also note that the contents of the pit hint strongly at repeated ceremonies involving fire and the deposition of unusual materials within the features. While the longevity of the monument also suggests the special knowledge associated with the pit arrangement appears to have been curated and maintained over a significant time. The Mesolithic monument was first spotted from the air during an aerial survey by a team from the Royal Commission on the Ancient and Historical Monuments of Scotland. It was originally excavated in 2004 by the National Trust for Scotland, with researchers led by a team from the University of Birmingham delving deeper into the ancient mysteries of this calendar in 2013. Considering this site, our view of hunter-gatherer societies in general has got to be reimagined. I'm going to put the bell and I'll speak to you soon.