Our Submerged Past

Land areas lost to rising sea levels since the last ice age (Courtesy Prof Vincent Gaffney) Land areas lost to rising sea levels since the last ice age (Courtesy Prof Vincent Gaffney)

For most of the time since modern humans emerged ‘out of Africa’ roughly 150,000 years ago, the northern hemisphere has been in the grip of an ice age, and sea levels were consequently about 125 metres lower than today. But now marine archaeologists are starting to find ways to uncover this missing period of our history, and the results promise to transform our understanding of our origins.

In fact, many of the familiar coastlines and estuaries of the world that we know have only existed for about 10,000 years. All the indications are that then, as now, about a third of the world’s population lived less than one hundred metres above the high-water mark, roughly the same amount by which sea levels rose at the end of the last ice age. Consequently many of the places our early ancestors lived are now inaccessible, submerged hundreds of feet beneath the waves – leaving large gaps in our knowledge of our past.

Investigating large areas of the sea bed on a scale fine enough to find human artifacts and settlements by traditional diving is an almost hopeless task. However, over the past decade, archaeologists have made enormous progress in developing other methods to uncover mankind’s history in areas now covered by the North Sea, the Arabian Gulf, and the Bering Strait, which were key population centres for our ancestors during the last ice age.

These discoveries are changing our understanding of our species’ development at a key period around 10,000 years ago when we started to become ‘civilised’, moving from hunter-gather lifestyles to begin to build and live in cities, supported by agriculture in fixed perennial locations. Here are a couple of examples.

Doggerland: the lost heart of Europe

One of the first submerged areas to be successfully investigated has been the southern North Sea between Britain and Europe. This large shallow area is known to fishermen as Dogger Bank, and trawlers have been bringing up Mesolithic artifacts up in their nets for around a hundred years – artifacts such as mammoth tusks, lumps of peat whose pollen indicates a woodland environment, and even antler points which have been worked by humans into harpoons – clear evidence that humans once lived there.

Fortunately, the area has been extensively surveyed by the oil industry, and archaeologists have been able to use the resulting seismic data to reveal the original land surface 10,000 to 8,000 years ago – now lying beneath about fifty metres of water and layers of sediment – and to map its rivers and valleys and even make 3D landscape models. Pollen samples from marine cores have then been used to add vegetation information to create a remarkably complete and vivid picture of this lost land, which archaeologists have now dubbed Doggerland.

Knowing better where to look, marine archaeologists have since dredged all kinds of man-made artifacts from the sea bed, giving an extensive picture of a human population who lived and hunted on Doggerland at the end of the ice age, what kind of animals they hunted and even their belief systems from artwork carved in bones and tusks. The people of Doggerland must have seen their island steadily shrinking as the ice sheets melted and sea levels rose, some gradually drifting away to drier lands – until one day it just wasn’t there at all.

The Garden of Eden: the ultimate archaeological site?

Arguably the place where humans have been most dramatically effected by past sea level rise has been the Arabian Gulf. Today`s Gulf is actually a very recent feature, only formed between 14,000 and 6,000 years ago by the same sea level rise that drowned Doggerland.

Prior to that, the Arabian Gulf Oasis, as it is usually referred to before the Gulf flooded, was a major human population centre for a very long time. When our ancestors first left Africa, one of their major exit routes was across the southern end of the Red Sea and southern Arabia, and then up into the Arabian Gulf Oasis. This fertile valley of over 250,000 sq km became a major population centre for humans for tens of thousands of years.

It was from here that our ancestors were to continue their global trek west into Europe, east to South East Asia and Australia, and north through Asia into Russia and China, from where they crossed the Bering land bridge into the Americas.

The Arabian Gulf Oasis is also the strongest candidate for a real-world location of the Garden of Eden, something that is supported by multiple evidence sources such as the description of rivers flowing through the Garden given in the Bible and the Quran, the locations where the legend was first recorded in ancient texts such as the Legend of Etana and the Epic of Gilgamesh, and the description of the flood in the Sumerian King List.

Human artifacts proving Mesolithic settlement have yet to be found beneath the Gulf in the same way as at Doggerland, but convincing evidence that it was once a regional centre of human development has come from another source. In 2010, Dr. Jeffrey Rose of the University of Birmingham mapped the occurrence around the Gulf of pottery and artifacts known as Ubaid style belonging to a relatively sophisticated people, all dated to around 8000 years ago. As Rose put it: ‘These settlements boasted well-built, perma¬nent stone houses, long-distance trade networks, elaborately decorated pottery, domesticated animals, and even evidence for one of the oldest boats in the world.’

The curious thing was, they were all found along the present day coastline of the Gulf, and they all appeared more or less out of nowhere, in areas with no previous history of fixed human settlement or those specific types of artifact. He concluded that the only explanation was that the people that made them had all come from a common origin, and that that origin had to be the Arabian Gulf Oasis. So the settlements and artifacts we find along the coast could only have been made by people from the Gulf.

The descendants of these Ubaid people went on to found the world’s first cities such as Ur and Uruk in present-day Iraq, invent writing, and develop civilizations. Marine archaeologists are now starting systematic sea bed searches for settlement remains similar to those found on land in an attempt to locate the earliest settlements in the Gulf Oasis.

In North America, another area of active research interest is the Bering land bridge between Alaska and Russia, which was a broad ice-free area during the ice age, and is now known to have been inhabited by humans for tens of thousands of years before rising sea levels engulfed it. Other signs of ice age human settlement have been found offshore Haida Gwaii on Canada’s west coast (the route which humans are believed to have taken as they migrated down into the Americas), and beneath Lake Huron stone structures for herding buffalo were recently discovered, built by the earliest First Nations people shortly after the ice sheets retreated.

Finally, these advances don’t merely fill in some of the blanks in our knowledge of our earliest human history. They also have a particular relevance for us today given concerns about the coming impact of rising sea levels caused by global warming; the difference is that back then humans were nomadic and could easily move to higher ground. With hundreds of millions of people living in large coastal cities with inflexible infrastructures, it will be much harder for us to adapt to such events in the future.

51k3knMByxLDavid Millar is a science writer with an interest in climate change past and present. He is the author of Beyond Dubai: Seeking Lost Cities in the Emirates which tells the tales of several Arabian lost cities abandoned through past climate change, as well as the story of man’s migration from the flooded Arabian Gulf Oasis towards surrounding lands to create the world’s first civilizations.

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