Diving and Sawing in the Bay of Bones

24 September 2019

Europe’s first farmers lived in pile dwellings in the Balkans. How did they adapt to new climate conditions and how did they influence their environment? A major EU project, initiated by Bernese researchers, is looking for the answers. We followed the research team for two days.

(Picture: Corinne Stäheli)

July 28, 10pm

It’s dark when we reach the Bernese researchers’ camp. Not a tented camp in the wilderness, but rather a house with a front garden in Peštani, a sleepy holiday resort on Lake Ohrid in northern Macedonia. A long table lit by flickering candles. A big pot of pasta on a striking coaster that’s as black and hard as ebony. It’s a slice of a 6,000-year-old wooden pile. Welcome to the world of underwater archaeology! Welcome to the European Excellence Project EXPLO (see box)!

At dinner there are ten archaeologists and divers, most of whom belong to both categories. In the first year of this project, about 40 people from half a dozen countries will come here over a two-month period.

Over a glass of red wine from the little shop across the street, Albert Hafner, professor of prehistoric archaeology, outlines the main elements of the project that he started with paleoecologist Willy Tinner, also a professor at the University of Bern. Both are members of the OCCR. “The backbone of the project is the high-precision dating of the piles to establish a chronology among the sites,” says Hafner. On Lake Ohrid, the team has already taken samples from about 800 piles – the remains of settlements from the Neolithic and Bronze ages. On the basis of chronology, EXPLO wants to show how the climate, environment and agriculture have developed over the past 10,000 years, and how they’ve influenced each other. They will also examine archaeological sites, drill cores and sediments from lakes in Greece, northern Macedonia and Albania. The five-year project should answer the questions: When exactly did the agricultural lifestyle begin on the southernmost edge of Europe? Why then and why here? This knowledge of the past should also provide lessons for the future, for example, through the farmers’ adaptation strategies for past climate change.

(Picture: Marco Hostettler)

July 29, 9am

Time for the last dive of the season. Three divers and their helpers load material. An inflatable black boat with a Bernese registration number fills with items like measuring tapes, trowels, a foxtail saw and even cake pans in various sizes. All packed in practical red shopping baskets. The excavation site is some 50 meters from the shore in the “Bay of Bones”. It’s not clear why it’s called this. The name “Bay of Pots” would be more apt since the ground is covered with a thick layer of Bronze Age ceramics. What is certain is that local divers discovered piles protruding from the floor of the lake.

Meanwhile, a reconstructed pile dwelling settlement stands in the picturesque and sheltered bay. There’s a diving centre on the shore. It’s from here that the EXPLO teams have been setting out over the past weeks. Their job? Clearing a 10x10m area of sediment, finding piles, noting their location and taking a sample from every piece of wood. It may sound relatively simple, but in fact it requires meticulous organization, high-tech equipment and hard physical labour at a depth of four meters. All the while, there’ve been underwater surprises that have brought the archaeologists to their limits.

(Picture: Marco Hostettler)

For example, they hadn’t expected such a dense network of piles. During the Neolithic and Bronze ages, up to 14 sharpened oak, coniferous and juniper trunks per square metre were rammed into the ground. It’s not that so many were needed to support the buildings; rather, the people kept rebuilding at this site. In their first evaluations, the Bernese researchers have concluded that over a dozen settlements were built here over the course of thousands of years.

This abundance of material is a stroke of luck, but the archaeologists have been less impressed with the effort required to secure samples of the piles. Soaked in water and buried in sediment without oxygen, the wooden posts aren’t just perfectly preserved – they’re as hard as rock. Especially the juniper wood proved problematic for the divers. Using a hand saw, it took a whole day and a half to cut a sample from one of these trunks. In addition to a lot of muscle strength, they needed five tanks of oxygen. For the next excavation session, they’ll clearly need an underwater chainsaw.

(Picture: Marco Hostettler)

July 29, 10:30am

The rubber dinghy bobs at a red buoy, the underwater archaeologists are at work, and now it’s time for the reporters – wearing a mask and snorkel – to get in the water. We swim to a pit where a diver in a red suit is creating a sediment profile. Via a short dive to the lake bottom we can see how that works: Measuring the exact location where the sample comes from. Choosing a suitable cake pan. Clearing the pit wall of stones and ceramic shards so it’ll be easier to press the pan into the sediment. And then pressing very carefully. Finally, rising to the surface and handing the full pan to the on-board crew waiting to pack the sample.

July 29, 12:30pm

Lunch break. Over bread, tomatoes, ajvar and cheese we talk about parallels between this excavation site and those in Switzerland.

We learn that they’re very comparable, but the one on Lake Ohrid is considerably older – and the archaeologists are doing pioneering research. In Switzerland, the first pile dwelling was found in 1854 already. Since the 1960s – thanks to the support of underwater archaeologists – the topic has been researched extensively. The oldest pile dwelling settlements in Switzerland were built in 4300 BC; the newest in 800 BC. In between, rising lake levels washed away settlement evidence many times. Today we know not just where and when the pile dwellers lived, but what grains they planted (such as barley and ancient Eurasian and Mediterranean wheats) and what animals they kept (like cattle, pigs and dogs). What’s also known is how they processed and obtained materials via established trade routes – like silex, for example. But there’s still much mystery surrounding questions like: What did differences in social class look like? How did these people bury their dead?

The first EXPLO results show that the pile dwellings in the Bay of Bones are much older than we thought. Previously, they were thought to have been built between 1200BC and 700BC. The Bernese researchers have identified three settlement phases: 4400BC, 1800BC, and 1400BC. But they’ve calculated that there were also settlements that had been established between 6000BC and 5000BC.

(Picture: Johannes Reich)

July 29, 5pm

In the furnished house that it’s rented, the EXPLO team runs a mobile laboratory for dendrochronology. Microscopes and tree cuttings stand next to the china cupboard and house bar. On the wall are maps of the Sutz-Lattrigen pile dwellings on Lake Biel, where, before his time at the University of Bern, Albert Hafner ran the field office for underwater archaeology. There he laid the foundation work for the recognition of the UNESCO World Heritage site, “Prehistoric Pile Dwellings around the Alps” – which comprises 111 sites in the six Alpine states.

Also pinned to the wall is the so-called South German-Swiss oak standard curve, an annual ring calendar that goes back to 9000BC. References like this are indispensable in accurately establishing the age of a tree. With its help, growth patterns examined under a microscope can be matched to a chronology, and the tree’s age can be determined. It took decades of research work to create the standard curve for lakeside settlements in the northern Alps. There’s nothing like it for the southern Balkans. “That’s why the introduction of dendrochronology in this region is a priority of EXPLO,” says Albert Hafner. For that reference curve, they’ll need more than just a wide variety of tree cuttings of all ages. They’ll also need statistical models and a multitude of C14 age datings, which the Oeschger Centre is carrying out in its radiocarbon laboratory.

EXPLO won’t be able to create a full 10,000-year chronology, but the combination of modern C14 data and dendrological data will provide a highly useful working tool. “When it comes to dating the prehistoric lakeside settlements in the region, we want to work with a clear chronology of scientific facts,” explains Albert Hafner. 

(Picture: Marco Hofstettler)

July 30, 4pm

Parked in front of the excavation house, the black and white minivans with the University of Bern logo are packed. In addition to all the equipment, there’s also room for all the vacuum-packed wood samples. Now archaeologist and EXPLO coordinator Ariane Ballmer, one of the few team members who spent the entire summer there, has time to talk about the major theme of the project: the spread of agriculture to Europe.

What do we know about the propagation of agriculture from western Asia to Europe?

Ariane Ballmer: It’s clear that from 7000BC, the early cattle breeders and farmers moved from Anatolia to the Aegean region, in particular northern Greece, and then to central Europe via southern Italy and the Balkans.

Did farming communities in fact migrate, or was it just the cultivating techniques that spread via hunter-gatherers who had been in contact with farmers?

When it comes to the introduction of agriculture, the thesis of adaptation through pure knowledge transfer is considered refuted since domestic animals and grains probably came to Europe along with immigrants from western Asia. There are also clues that European hunter-gatherer groups helped adapt these innovations to the local conditions.

(Picture: Johannes Reich)

The new European farming communities lived under other climatic conditions than those of western Asia.

Yes, they had to adapt to a variety of new conditions, not just climatic. This challenge likely brought successes as well as failures, and led to new strategies and innovations over many generations. For example, they managed to get barley and wheat from the dry, subtropical climate of the Middle East to grow well in the cool, damp and woodland conditions of Europe.

This is where the interdisciplinary cooperation of EXPLO comes into play: Oxford professor Amy Bogaard specializes in early agricultural ecology. Using prehistoric food leftovers found in the sediment of diverse archaeological sites, she wants to determine what the people planted and ate here. Her goal: a bioarchaeological reconstruction of early European agriculture. Meanwhile, Willy Tinner wants to analyse how the first farmers influenced their environment, and vice versa. The paleoecologists in particular can clarify whether the introduction of agriculture was an abrupt of gradual process. The dendrochronologists, for their part, will prove when exactly the first settlements were built in the southwestern Balkans – and how long people lived there. Ultimately, this will show how fast the first European farmers managed to adapt to the new climate.

(Picture: Johannes Reich)

July 30, 9pm

After dinner, research diver and dive team leader Johannes Reich grabs his laptop. The future PhD student, who will write his dissertation on the EXPLO project, shows us visualizations made from hundreds of underwater photos. With an underwater camera his team documented the whole exposed excavation field. In the evenings, Reich used the images to create a 3D surface model and linked it to the precisely measured pile locations. Now, before our eyes, a veritable forest of tree trunks juts out of the lake floor.

Back in Bern this model will be linked to the ages of the various piles, and trees of the same age will be color-coded. Then it should be possible to see floor plans of the houses in the wild pattern of wooden posts – like in the plans of the pile dweller settlement on Lake Biel. “I expect that based on the samples from this season’s archaeological dig, we’ll be able to reconstruct the first floor plans of a Balkan lakeside settlement,” believes Johannes Reich, adding, “That alone would be a huge success.”

It’s clear that underwater archaeology is bone-tiring hard work. That’s also the case here in the “Bay of Bones” – which doesn’t deserve its macabre name at all.

(Source: UniPress, University of Bern)

European excellence project

EXPLO (Exploring the dynamics and causes of prehistoric land use change in the cradle of European farming) is supported by the EU with €6.4 million. It was one of two dozen interdisciplinary projects awarded an “ERC Synergy Grant” in 2018 – and one of the very few humanities projects. Highly coveted among researchers, the Synergy Grants represent the European Commission’s highest level of excellence funding. Fewer than 5% of the submitted applications are approved.