From earliest history, mankind has been fascinated by the sky and its two most prominent occupants – the sun and the moon. It was only natural that we should start to keep track of the fluctuations in these two celestial objects. The passage from day to night is one obvious interval, as is the cycle from new moon to full moon and back again. And for hunter-gatherers or early farmers, it was also crucial to understand the rotation of the seasons through the year.
Making sense of these various measures was a complex task. For instance, there is no tidy number of lunar months in a solar year. Twelve lunar months take about 354 days and you either need to find a way to add those odd days back into your system or to accept a gradual slippage in how the years relate to the seasons. And that’s before you even start to think about the problem of leap years ...
Calendars of various sorts were clearly in use before the Bronze Age. We have written records of calendar systems from the Sumerian, Egyptian and Assyrian civilizations dating to about 5,000 years ago. However, one recent archaeological find in a field in Scotland, at Craithes Castle in Aberdeenshire, suggests that calendars were in use much earlier than that.
The site contained a series of twelve pits, which seem not only to show the phases of the moon but also to monitor lunar months. The pits, which have been dated to 10,000 years ago, also align with the midwinter sunrise. This would allow the hunter-gatherers who created them to reset each year correctly to align with the seasons, which suggests significant levels of understanding and sophistication in the pre-agricultural Mesolithic people of the area. The academic Vince Gaffney, who was in charge of the scientific analysis of the site, said that it ‘illustrates one important step towards the formal construction of time and therefore history itself’.