Artificial islands commonly known as crannogs dot hundreds of Scottish and Irish lakes and waterways. Until now, researchers thought most were built when people in the Iron Age-800-43 BC-created stone causeways and dwellings in the middle of bodies of water. But a new paper published in the journal Antiquity suggests that at least some of Scotland's nearly 600 crannogs are much, much older-nearly three thousand years older-putting them firmly in the Neolithic era. What's more, the artifacts that help push back the date of the crannogs into the far deeper past may also point to a kind of behavior not previously suspected in this prehistoric period.
A possibility that some crannogs may date as far back as the Neolithic first arose in the 1980s, when archaeologists excavating an Iron Age islet in a lake on Scotland's North Uist island realized they were looking at a Neolithic site instead. But though researchers suspected it wasn't the only case, searches of other crannogs in subsequent years yielded no evidence of Neolithic origins.
That changed in 2012 when a local diver found distinctively Neolithic pottery in the water around crannogs in the Outer Hebrides, the windswept islands off of Scotland's western mainland. Local museum officials and archaeologists joined in the search and eventually identified five artificially constructed islets with Neolithic origins, based on radiocarbon dating of stone-age pottery and/or ancient timbers discovered near the edges of the artificial structures.
For archaeologists used to finding just bits and pieces of six millennia-year-old pottery, the condition of the nearly intact Neolithic ceramic vessels found in the water around the crannogs is "amazing," says Duncan Garrow, an associate professor of archaeology at the University of Reading, who co-authored the paper. "I've never seen anything like it in British archaeology," he says. "People seem to have been chucking this stuff in the water."
But why were Neolithic people tossing their "good china" off of artificial islands? Garrow and his colleagues surmise they were used for feasting, another unknown set of religious or social rituals, or both. Vicki Cummings, an expert in Neolithic monuments from the University of Central Lancashire who was not involved in the research, says these crannogs appear isolated from both everyday Neolithic life-since they're located away from domestic settlements-and death, due to a lack of tombs or human remains.
Cummings suggests the sites' isolation, and the pottery that surrounds them could point to rituals that marked life transitions-like the passage from childhood to adulthood. "Clearly it was not appropriate to take the pottery [brought to the Neolithic crannogs] home," she says.
Paper co-author Garrow admits the research is only just beginning, and his team plans to conduct a broader survey to date more crannogs in the Outer Hebrides. He hopes to use the scientific techniques that helped home in on the Neolithic crannogs-such as underwater surveys using side-scan sonar- to create even better ways of spotting new artificial stone-age islets, or prompt a reconsideration of sites already written off as Iron Age in origin. Still, it's unclear if the practice was widespread, and given the sheer volume of crannogs and the expense of surveying and archaeological diving, it's unlikely researchers will be able to date all of them any time soon.
