Periodic Reporting for period 1 - DREGS (Deciphering archaeological Residues to understand the history of European Grape cultivation and winemaking Societies)
Reporting period: 2019-09-01 to 2021-08-31
The actions of horticulturalists in Western Asia some 8000 years ago transformed a wild plant bearing small, acidic berries into the domesticated grapevine (Vitis vinifera), changing the course of history in ways early farmers could never have foreseen. Today the grapevine is the world’s most economically important fruit, with berries consumed fresh, as raisins, as juice, but principally, as wine. In addition to being associated with merriment and fine cuisine, wine plays important roles in religious and secular rites, frequently symbolizing fertility and abundance. Scholars have sought to understand the history of winemaking, gathering insights from archaeological evidence, historical documents, and genetic data from wild and cultivated vines, but despite decades of research, we still have major questions regarding the history of ancient viniculture. In particular, researchers have wondered when and where were white berries first propagated by people, when varieties became established and incorporated into local traditions, and how winemaking changed during times of cultural upheaval. The DREGS project seeks to explore these questions through the biomolecular analysis of archaeological grape seeds and artefacts. Through genetic testing of seeds and multidisciplinary analysis of artefacts, new insights on the history of winemaking and grapevine cultivation will be revealed. In turn, these will shed new light on the European cultural traditions of wine and wider agricultural practices.
In this project, ancient DNA has been recovered from dozens of archaeological grape seeds excavated from near the Mediterranean Basin. As expected with ancient DNA research, some seeds have no DNA preserved and cannot be used to explore the questions of the project. However, in some circumstances, such under waterlogged, anaerobic conditions, the seeds continue to protect the DNA, and provide access to a large amount of genetic information. This ancient DNA is compared to the genetic fingerprints of modern grapevine varieties and wild vines which grow across the Mediterranean Basin and toward the Himalayas. In the case of cultivated grapevines, most varieties are maintained through vegetative propagation, such as through cuttings or grafting. This mode of horticulture effectively creates clonal lineages which share nearly identical genetic signatures. By examining how archaeological samples relate to the modern clonal lineages, we can infer when certain varieties were established and how they were traded and transported in antiquity.
In a parallel line of inquiry, the DNA recovered from ancient artefacts may be used to understand the ancient contents of amphorae and other storage vessels. Ancient DNA research has demonstrated the great analytical power of the approach; however, questions have been raised about the risk of transfer of environmental DNA to artefacts. In DREGS, archaeological sherds have been tested for DNA and lipid residues to better understand the stability of these molecules over time.
In a parallel line of inquiry, the DNA recovered from ancient artefacts may be used to understand the ancient contents of amphorae and other storage vessels. Ancient DNA research has demonstrated the great analytical power of the approach; however, questions have been raised about the risk of transfer of environmental DNA to artefacts. In DREGS, archaeological sherds have been tested for DNA and lipid residues to better understand the stability of these molecules over time.
The project has been designed to maximize the recovery of useful data from archaeological samples, using a multidisciplinary approach. Methods have been explored including digital preservation of sample appearance and shape, optimised recovery of ultrashort DNA from small seeds, removal of compounds co-extracted with DNA, state-of-the-art sequencing methods, and specialised bioinformatic methods to observe genetic relationships even with degraded DNA. The findings are revealing how grapevine cultivation changed from the Bronze Age to modern periods, with implications for the history of winemaking and agriculture. These results are expected to be equally important to those in the wine industry, consumers of wine, and wider audiences who appreciate the significance of the longevity and stability of cultural traditions.