When wild boars became pigs

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When wild boars became pigs

The start of agriculture in the Netherlands is still surrounded by mysteries. How did animal husbandry start, for instance? And when exactly? Which role did domesticated animals play in Neolithic life, and to what extent did they interbreed with wild animals? Zooarchaeologist Canan Çakırlar is addressing these questions – and more – in a new NWO-funded project. It touches on themes that are more relevant than ever: a changing climate and the intimate links between human and animal health.

Canan ÇakırlarCanan Çakırlar

Buried deep in the sediments of the Low Countries lie the bones of people and their livestock. Many are still there and may never be found. But some have surfaced at places that are now concepts in our history books, such as Swifterbant and Hazendonk. Those bones lie in depots and museums, but most of their stories are still untold. What kind of bones are they, really? Are they pig or wild boar? Aurochs or cow? How old are they? We don’t really know.

These mysteries have long intrigued Canan Çakırlar. She is from Turkey and has been supervising the Zooarchaeology Lab of the University of Groningen’s Institute of Archeology since 2012. Early 2020, Çakırlar and Daan Raemaekers, professor of the Archaeology of Europe, started a three-year research project under an NWO Social Sciences and Humanities Grant. ‘The project is called EDAN: The Emergence of Domesticated Animals in the Netherlands’, says Çakırlar. ‘By studying previously excavated animal bones, we aim to unravel how people lived in this region during the transition from hunting-gathering to agriculture.’

This statistical approach links archaeological bones, sediment layers, and radiocarbon dates more tightly, providing the most probable, narrowest timeframe possible
- Canan Çakırlar

Modern technologies

This transition took place in the Netherlands sometime in the Neolithic, but it is still unknown when exactly. Çakırlar: ‘Our best guess is that it happened towards the end of the fifth millennium BC.’
To place archeological finds such as bones in a timeframe, scientists use modern technologies, such as radiocarbon dating. This technique studies the decay of radioactive carbon over time. It sounds exact, but in reality is a complicated puzzle. Radiocarbon footprints may have been influenced by atmospheric variation. ‘Therefore we plan to use a statistical approach’, says Çakırlar, ‘which has never been used in Dutch archaeology before. My colleagues Michael Dee, Hans Peeters and PhD candidate Merita Dreshaj will be focusing on this part. This statistical approach links archaeological bones, sediment layers, and radiocarbon dates more tightly, providing the most probable, narrowest timeframe possible.’

Wild boar and aurochs

The people who lived around the places that we now know as Swifterbant and Hazendonk originally lived off the wetlands. They trapped bevers and otters, picked plants and berries, caught fish and waterfowl, and hunted boar, deer and aurochs. At some point in the archeological record, some bones start showing up in relatively larger quantities: bones of pigs and cattle. ‘They may have belonged to wild boar or aurochs, though’, Çakırlar remarks. ‘It is hard to see the difference.’
Çakırlar hopes that this will become clearer through ancient DNA analysis, carried out by PhD student Jolijn Erven and Ole Madsen, geneticist from Wageningen University.

Jolijn Erven and Dr. Youri van den Hurk looking for suitable bones at the zooarchaeological collections of the Faculty of Arts, RUG.Jolijn Erven and Dr. Youri van den Hurk looking for suitable bones at the zooarchaeological collections of the Faculty of Arts, RUG.

‘The more we look at these bones, the more signs we see of interbreeding between wild and domesticated animals’, says Çakırlar. ‘Domestication is a fascinating process. It manifests itself as a package of genetic changes, related to external features and behaviour, but also to things like the immune system. It is amazing stuff. It requires a huge bioinformatics effort to unravel this process.’

Round, pink pigs in a sty

It has long been assumed that domestication either took place locally, starting from local wild populations, or that it was imported from the sites where domestication originally took place: in the Near East. ‘But in reality’, says Çakırlar, ‘recent research shows that it also happened along the way, in a winding and very complex fashion.’
Domesticated animals have constantly interbred with their wild conspecifics, she argues. And ‘domestication’ itself is a sliding scale, too: groups of pigs were often free-ranging, eating a mixture of foods they found in the forest and household wastes on the edges of settlements. If they mixed with wild boar, to what extent were they domesticated? In commensal living situations, when does a boar become a pig?
‘It took a long time before people had these round, pink pigs in a sty’, says Çakırlar. ‘By looking at the morphology of the bones, reconstructing population-wide trends, and analysing the stable isotopes in the bone tissue, we hope to deduct what these pigs were eating – and thus, how such a transition took place.’

State-of-the art accelerator used to radiocarbon date the animal bones at the Centre for Isotope research at the RUG.

Intimate relationship

Ultimately, these methods and results will help to update the image that we have of Neolithic people and their way of life. Living with animals, as Çakırlar emphasizes, changes people’s lives at a fundamental level. It makes them less mobile and less dependent on their environment, but that is not all. ‘The relationship is very intimate’, she says. ‘You cannot milk an aurochs, for instance. Milking is super difficult: it requires a great level of trust and patience on both sides.’
Nathalie Brusgaard, the postdoctoral researcher in the project, will investigate the stable isotope ratios in cattle teeth to see when we see first signs of milking and in which interactive context. Çakırlar: ‘This project dovetails nicely with ongoing research on lipid residues in the earliest pottery in the Netherlands, also conducted at the Groningen Institute of Archaeology.’

Human  and animal health

It will be a data-heavy project, she adds. ‘If you are lucky enough to have good people, which we do, then the technological part will not be the biggest challenge. More challenging is the interpretation of the results. We try to look at it holistically, by making connections between diet, environment, mobility and the sharing of space, for instance.’

Did you know? The stone age is a fascinating period in which many changes happened very rapidly

It is a fascinating period, she concludes, in which many changes happened very rapidly. Cultivation of crops and domestication of animals went hand in hand – along with interbreeding with wild species. Çakırlar: ‘That combined process is the root of all the things that we do today.’
And of the challenges that we face today in the areas of climate change and global health, she adds. ‘Human and animal health became linked in that period. And humans were able to adapt to past environmental changes in large part thanks to animals. Those are just some of the reasons that this research is not just fascinating, but also relevant today. Our history has been entangled with that of other species since the Neolithic.’

Text: Nienke Beintema
Photos: Canan Çakırlar

This research project received a grant from NWO:
The Beginning of Dutch Animal Husbandry: Chronology, Nature, and Impact
Prof. dr. Daan Raemaekers (RUG)
The start of animal husbandry is of major importance for the culture and natural environment of Europe. This project studies the start of animal husbandry in the Netherlands using various new techniques. This will lead to a better understanding of the way in which prehistoric people interacted with their livestock.

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