[ ♪ Intro] The Faroe Islands are an archipelago  set between Norway and Iceland.

Because these islands are so  remote, historians believe they were one of the last places on  earth to be settled by humans. The most popular theory says that  the Vikings were the first to settle the Faroes, arriving sometime  in the mid-9th century.

But some researchers think that  the Faroes could have been settled much earlier, by an unknown group  of people. How do they know? Why, a volcanic eruption from  centuries ago, of course.

Studying early human migration  doesn’t just help us understand the history of our species, it also helps  us understand the effect that humans, even pre-industrial humans, have  had on the natural environment. Since the Faroe Islands were settled  so recently, the picture is clearer than in most other places. Now, there is some prior evidence  that humans were in the Faroes earlier than we thought.

We don’t  have much in the way of direct physical evidence like artifacts  or remains. So we’ve had to turn to some more tenuous lines of evidence. A study published in 2013 showed  that ash patches in the Faroe Islands contained the remains of barley  grains, a human-cultivated crop not found in the wild, from  as early as the 4th century.

But on its own, that doesn’t amount to proof. The same can be said for studies  of how the Faroe Islands’ ecosystem has evolved over time.  They demonstrate significant environmental change before the  9th century, going from heavily forested to mostly grass. Humans have always been very  good at making huge environmental changes to the land they settle in,  harvesting wood from forests and clearing space for farms and livestock.

But again, the evidence is circumstantial. Sure, humans could have caused those changes, but so could other natural factors. So none of that really tells  us humans were present on the Faroe Islands before the Vikings and  driving their environmental change.

But archeology isn’t all  dusting off bits of broken pots. A study published in 2021 presented  way more conclusive evidence and it got a big leg up from geology. This evidence was hidden in layers  of volcanic ash, deposited from ancient eruptions 700 kilometers  northwest of the Faroes, in Iceland.

Seven hundred kilometers isn’t  that far away, on a global scale. That’s about the distance between  New York City and Detroit. And volcanic ash can travel a long  way, especially from large eruptions.

In 2010, the eruption of a volcano  in Iceland grounded flights across the European continent, much farther  away from Iceland than the Faroes are. Which means ash wouldn’t have  any trouble reaching the Faroes, and leaving evidence for geologists to interpret. Now, volcanic ash is actually made  of microscopic shards of glass, which are projected into the  atmosphere every time a volcano erupts.

When that ash eventually falls  out of the atmosphere, some of it ends up at the bottom of lakes,  forming distinct layers of lake sediment that are clearly volcanic in  origin. These layers are called tephra, and every eruption has its own distinct  chemical signature, which is locked into the tephra like a fingerprint.  Chemical analysis of tephra can tell researchers where an eruption took place. More than that, if there are  other records of that eruption, you can work out when that eruption took place.

Normally, matching a sediment  core’s layers up to actual dates is a difficult process, requiring  intensive dating methods. But using tephras can shorten the process. Because every tephra signature  is unique and comes from a separate eruption, once  the you know the date and chemical signature of an  eruption anywhere in the world, you’ve basically got a number corresponding to that layer anywhere you find it.

When researchers looked at  a sediment core pulled from a lake in the Faroes, they found  10,000 years worth of sediment layers. Most of it was normal sediment  that comes from erosion and rain. But hidden in those sediments  were several tephra layers, and one of those was the Landnám tephra.

The Landnám tephra had already been  linked to an Icelandic eruption that happened in 870 CE, only a few  decades after the arrival of the Vikings. And decades are pretty minuscule on a  geologic time scale, so in a core like this, we can say that the Landnám  tephra marks the moment when the Vikings arrived on the Faroes. If the Vikings were really the  first settlers, there would be no evidence of human activity  in parts of the sediment core older than the Landnám tephra.

But deeper in the sediment  core, about 300 years before the arrival of the Vikings,  researchers found traces of sheep DNA. Sheep aren’t native to the Faroes,  and were introduced by settlers. So this finding shows that  humans lived in the Faroes sometime around 500 CE.

The Vikings weren’t the first  people on the islands after all! We still know very little  about those first settlers. We suspect they could have  been from the British Isles, but we aren’t sure if they were  around when the Vikings arrived, or what happened to them.

But the discovery answers  other questions, like how the environment of the Faroes changed so drastically. Humans modified the environment  with their livestock. The new results can help  archaeologists reconstruct the timeline of human history far beyond the Faroes.

Researchers can use the same techniques  to help map global migration, especially in places where there  are no remains left behind. It can also help paleoclimatologists  and other scientists understand how quickly humans  can reshape natural environments, and whether a past environmental  change was caused by humans at all. Which is a lot to learn from one  little archipelago.

Not just that this mysterious group of folks managed  to beat the Vikings somewhere, but just how much geology can tell  us about archeology the world over! Thanks for watching this episode  of SciShow, and a huge thanks to the patrons who helped to bring it to you. We have an awesome community, and  if you’d like to check them out and see what it’s all about,  head over to patreon.com/scishow. [ ♪ Outro]