RESOLVING THE FISHER-FARMER CONUNDRUM IN PREHISTORIC EUROPE USING BIOMOLECULAR APPROACHES (AquaNeo)

For most of the modern human evolution, humans were depending on food resources they hunted, gathered and fished. The transition to the Neolithic saw a major change in subsistence, with the introduction of domesticated plants and animals in human diet. Many coastal populations of early farmers turned their back from the sea and were not consuming marine foodstuffs. Little is known about early farmers from inland locations and their use of aquatic resources from rivers and lakes. Together with milk, aquatic resources are the only foodstuff available to farmers that are a source of vitamin D3, crucial for bone health in most of Europe where exposition to UVB are insufficient. Aquatic foods may thus have played a key nutritional role in farmers' diet, particularly in regions where milk was not greatly exploited. However, fishing and trapping skills are very much part of the hunter-gatherer life-ways. Aquatic resource use in farming communities is thus likely to show that these skills were transmitted from residual hunter-gatherer populations to early farmers (cultural hypothesis). Beyond the mere ease-of-access to productive rivers and streams, the use of aquatic resources by early farmers is hypothesised to have been shaped by nutritional necessity and access to cultural skills.

Aquatic skeletal remains are very small and fragile, and traditional methods for the detection of consumption of freshwater resources using human bone collagen is extremely challenging. We are targeting pottery sherds to detect the use of freshwater resources at early (inland) farming sites. Indeed lipids (or fats) trapped in pottery pores provide evidence for what was cooked in ceramic vessels. By characterising lipids using state-of-the-art analytical methods, we will be able to detect well-known compounds (or biomarkers) characteristic of aquatic resource processing. We will develop a novel method using a highly sensitive instrument to detect extremely low amounts of such biomarkers in the lipid assemblage of pottery extracts. We will also use the aquatic biomarkers and the carbon isotope signature of ubiquitous compounds found in animal fats (C16:0 and C18:0 fatty acids) to build a mixing model to quantify the amount of freshwater-derived animal fats in each pottery vessel.

There is very much uncertainty into whether proteins from foodstuffs would survive on archaeological pottery sherds - if so, they would provide very complementary insights to lipids as they are species-specific (while lipids are not). We will test the stability of foodstuff proteins by cooking diverse foodstuffs (including different types of fish) in replica pottery. We will then sample parts of the vessels and bury them in compost under two different conditions for 18 months to mimic archaeological degradation. We will then analyse the sherds using palaeo-proteomics methods to assess whether foodstuff proteins have survived and how well.

We have >1,500 archaeological lipid extracts and sherds curated in Bristol that were obtained from our European-funded NeoMilk project. We will select extracts and sherds from various farming sites across mainland Europe to investigate aquatic lipid biomarkers and proteins. That will enable us to assess the level and type of freshwater resource use at those sites. This novel data will be extremely valuable to detect sherds that were not used for cooking freshwater resources - they will be used to demonstrate that lipids preserved within can be 14C-dated and be used to build robust chronologies as they are not affected by an "old-carbon" effect.

Finally, we will use models to study the link between the use of freshwater resources by early farmers and ecological (accessibility to water bodies), nutritional (milk use, exploitation of hunted game) and cultural (contact with hunter-gatherer populations) parameters. This project will highlight the importance of freshwater ecosystems to human populations in the past, present and future.