Go north, science fan!

The world's most northerly science festival takes place this September, above the uppermost tip of mainland Scotland. More than 3000 visitors are expected to make it to the 18th Orkney International Science Festival. Unsolved mysteries concerning the ancient isles of Orkney will be among the subjects under discussion.

The 70 plus islands (only about 20 of which have people living on them today) which make up the Orkneys have been inhabited for thousands of years. They were probably among the very last sites in Britain to be colonised by humans when the ice sheets of the last great Ice Age gradually withdrew about 8000 years ago.

The very first evidence of human habitation is a hazelnut shell recovered last year from beneath a later-built mound, which has been dated to 6820-6660 BC. This was left behind by hunter-gatherers who left few traces behind them.

The Neolithic (this means ‘New’ Stone Age) people who came after them were very different, erecting grand-scale dwellings and stone megaliths whose precise purpose remains enigmatic to this day. Orkney is home to the oldest stone-built house in northern Europe, at Knap of Howar, and the world’s single best-preserved Neolithic village, called Skara Brae.

Skara Brae appeared in a single night in 1850, when a great storm stripped grass from a stretch of coast, revealing the outline of buildings beneath. The excavations that followed revealed an entire Stone Age settlement had been preserved Pompeii like beneath many centuries worth of earth and sand. Archaeologists have gained a unique window into the everyday lives of our ancient ancestors – even prehistoric human fleas have been uncovered.

Another remarkable site dating from slightly later is the grand mound and chambered tomb of Maes Howe – although even this newer site is still older than the Egyptian Pyramids. Archaeologists have found the main passage entering the tomb is precisely aligned with the winter solstice – at midwinter sunset the light from the dying sun reaches all the way to the rear wall of the tomb.

Across Orkney new discoveries keep on being made. As recently as 1999 a local farmer made a find worthy of Indiana Jones – 29 steep stone-hewn steps which stretch down to a prehistoric chamber six metres (20 ft) underground. Known as Mine Howe, the artificial cave had previously been misidentified as an Iron Age burial site but actually turning out to be much older, up to 5000 years old. Its function remains unknown, but there are many theories…

The stone-based society that created such grand monuments was in disarray by around 2000 BC. The exact reason why is lost to us, but it may well be due to climate change, and many settlers may have retreated to warmer lands to the south.

There were still inhabitants during the Bronze and Iron Ages, and the Romans traded with them, and may even have briefly claimed the islands for their Empire. Then in the 9th Century Orkney came to the attention of the Vikings, who used the island as a base for raids.

Today the islands have a population of around 21,000, but who are they descended from? Orkney is proud of its Viking heritage, but among the topics at the Festival will be evidence from DNA surveys that suggest the origin of its people may well be more complex – and puzzling.

For more information on the Orkney International Science Festival – including the full programme of events, to be released in August – visit http://www.oisf.org.