The world's oldest "calendar" is believed to have been discovered in a Scottish field.
Twelve pits excavated in Aberdeenshire appear to mimic the phases of the moon over the course of a year, according to new analysis by experts.
Until now the first formal time-measuring devices were thought to have been created in Mesopotamia - now Iraq, north-east Syria and parts of Turkey - about 5,000 years ago.
However, the pit alignment near Crathes Castle predates those discoveries by thousands of years.
The monument, which was excavated between 2004-06 and recently analysed by a team led by the University of Birmingham, is said to have been created by hunter-gatherer societies nearly 10,000 years ago.
Researchers said the monument also aligns on the Midwinter sunrise, which they said would provide an annual "astronomic correction" to maintain the link between the passage of time indicated by the moon, the solar year and the seasons.
– Vince Gaffney, professor of landscape archaeology at the University of Birmingham
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.
In doing so, this illustrates one important step towards the formal construction of time and therefore history itself.
The pit site was first discovered when unusual crop markings were noticed during an aerial survey by the Royal Commission on the Ancient and Historical Monuments of Scotland.
It lies on the National Trust for Scotland's Crathes Castle estate and was excavated by the trust and Murray Archaeological Services.
– Dr Shannon Fraser, National Trust for Scotland's archaeologist for eastern Scotland
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.
The research was published in the journal Internet Archaeology.