DNA excavations uncover indigenous grain subsistence on the Canary Islands

Up to a thousand year-old barley seeds hidden away by the indigenous population inside volcanic rock silo systems and mountainous caves have allowed researchers to conduct unprecedented genotyping of archaeobotanical specimens. This study helps bring about a better understanding of human subsistence from the Palaeolithic and Epipalaeolithic prehistoric periods to the modern day.

‘The conditions in these caves were ideal for storage, and it is possible today, more than 500 years later, to find intact seeds in some of the most remote and well-hidden caves,’ explained Jacob Morales from the University of Las Palmas de Gran Canaria, and one of the main study researchers.

The results published in the ‘Journal of Archaeological Science’ have revealed striking genetic similarities between Canarian barley found today and in prehistoric times. The joint study, involving academics from Spain’s University of Las Palmas de Gran Canaria and Linköping University in Sweden, genotyped 640 individual barley grains and made a comparative analysis of over a hundred different genetic variants from the Canary Islands, in northern Africa and the western Mediterranean, cultivated through various time periods. Crucially radiocarbon dating (AMS) indicated that the age of some the seeds found ranged from 1050 to 1440 cal AD and most likely from the pre-Hispanic era.

In short, compared with seeds emanating from mainland Africa and Europe, researchers have now managed to unearth Canarian archaeological material barley that has a unique genetic cluster going back centuries and before the conquest of the Canary Islands by the Crown of Castille.

‘Since the original population has been replaced to a large extent by people from Spain, we were interested to see whether the barley had also been replaced. We found, however, that what is cultivated on the Canary Islands today is exactly the same barley as the original population brought to the islands when they were colonised early in the first millennium AD,’ asserted Jenny Hagenblad, associate professor at Linköping University and a study co-author.

Whilst the exact origins of the indigenous people – the Guanches – in the Canaries are the subject of many theories and debates, what is now certain is that barley has been exceptionally preserved as the main crop on the islands. Starting with the indigenous peoples protecting and even hiding their valuable harvest in prehistoric caves, through Hispanic settlers in the 14th and 15th centuries, to today’s farming community, this seed seems forever ingrained into the Canary Islands’ DNA.

‘We also learned a great deal about the barley that was cultivated in prehistoric times. The genetic markers we have used show that the barley had a high nutritional content, and each plant produced many seeds. The barley seems to have been well adapted to the conditions on the Canary Islands, and this is something that the Spanish conquerors probably noticed,’ stressed Matti Leino, associate professor at the Nordic Museum and previously at Linköping University.

These findings of genetic similarity now provide the exciting prospect of conducting future population studies of ancient archaeological DNA remains on a larger scale to further reveal Earth’s buried history.

The PALEOPLANT project, which officially ended in December 2015, aimed to better understand how plant foods and resources were used by pre-agrarian societies. The project received nearly EUR 385 000 in ERC funding.

For more information, please see:
CORDIS project page