The find was made in an underground chamber of The Cairns broch on South Ronaldsay along with several other tantalising finds, including a wooden bowl which may have been used to pass drink around a social gathering.
Martin Carruthers, lecturer at UHI Archaeology Institute, said the hair was now being tested to confirm its composition and could offer a new wave of information about ancient life in Northern Scotland.
He said: “We have made a number of astonishing finds at The Cairns, including strands of hair. My hunch is that it is human hair.
“We have around 20 strands. That is just what we could see and I am sure there will be other strands in the soil samples we have taken.
“It looks like human hair, it is pliable, if you blow on it, it moves. It is shiny, dark and measures around eight to 10 centimetres long so potentially it records eight to 10 months of information about diet and the conditions people were living in.
“We are hoping it will help up build a very rich picture of what was going on around that building and really drill into the detail of the humans living there.
“We have recovered some human remains from the site in the past, such as a mandible and the odd tooth, but nothing as exciting as the hair which gives us enormous potential to give us a more vivid picture of the humanity of the broch.”
The hair and the bowl were found within the subterranean chamber of the broch - a massive domestic roundhouse- known ‘The Well’.
Other finds include a piece of wood that resembles a tent peg, complete with notch. Part of the chamber was also covered in tiny pieces of twig, which may have been used as some sort of filter.
Several pieces of heather were also recovered, with a number of heads apparently woven together.
“That was amazing to see as it was human hands that have woven those pieces of heather together,” Mr Carruthers added.
The bowl recovered from the chamber is the oldest wooden bowl to be found in Orkney.
Made from alder, it a complete wood-turned bowl around 30 centimetres in diameter, with an elegant profile, a globular body and rounded base.
Although the object has split at some point in the past, it is complete and was being held together and protected by the muddy silts of the excavation.
Mr Carruthers, Lecturer in Archaeology at UHI Archaeology Institute, said: ‘It’s miraculous that we’ve got this wooden vessel.
“It’s really quite unprecedented preservation for a northern broch, and I still can’t believe it has turned up at The Cairns!.2
“In appearance, the bowl is similar in shape to certain of the pottery vessels of the period, and in particular it looks like the sort of vessel we suspect to have been used for serving food or drink.
“Its round base makes you think that it would have been required to be constantly held when full, and perhaps used socially, passed around from hand to hand, person to person.”
The bowl has already been nicknamed the ‘Cairns Quaich’ or the ‘Cairns Cog’ after the traditional drink served at Orkney weddings.
The Well features a series of stone cut steps descending into a carefully constructed stone chamber and was sealed when the broch went out of use and abandoned sometime between the Later 1st and Mid-2nd Century AD.
It is assumed that the items also date from this period also, however, radiocarbon dating will be required to see if it could be even earlier than this time.
Around 20 such ‘wells’ have been found beneath brochs with the conditions at The Cairns offering unusually good conditions for preservation.
Mr Carruthers said it appeared the silts within the well have been sealed in an anerobic or anoxic state, without oxygen.
The conditions mean micro-bacterias have not had an opportunity to eat away at the items.
This had led to an “incredible preservation” of organic items, usually only seen in the rarefied conditions of wetland sites such as the preshitoric loch village at Black Loch of Myrton in Dumfries and Galloway.
However, the well at The Cairns sits over two metres under the floor of the broch, and a further two metres beneath the modern ground surface.
The depth of the base of the well has remained damp since the Iron Age and allowed for the protection of the wood and organic items, Mr Carruthers said,