First Extraction of Ancient DNA from Pea and Bitter Vetch

Ancient DNA (aDNA) is any DNA extracted from ancient specimens. The study of aDNA enables us to comprehend biological and genetic changes over time, which provides us with direct insight into past genetic variation. The study of aDNA is crucial for the understanding of (the history of) agriculture or even liguistics. The study spawned a novel discipline called paleogenetics.

[Charred seed of pea (left) and bitter vetch (right)]

Legumes or pulses, such as chickpea (Cicer arietinum), lentil (Lens culinaris), pea (Pisum sativum) or bitter vetch (Vicia ervilia), a close relative of the fava bean (Vicia faba), are among the first domesticated plant species[1]. They were already consumed around 10,000 BC by Paleolithic hunter-gatherers[2].

The first extraction of legume aDNA was done from charred seeds of pea (Pisum sativum) and bitter vetch (Vicia ervilia) from Hissar, southeast Serbia, dated to 1,350–1,000 BC[3]. Hissar belonged to the Early Iron Age cultural group of Brnjica and most likely was the northernmost point of then Hellenic-based civilisation, dated back to between 1,350 BC and 1,000 BC.

These charred seeds were carefully chosen for analysis, avoiding any possibility of contamination with the DNA of modern pea or related genera, and their DNA was extracted from bulk, due to their age, a considerable degree of physical damages and assumingly low amount of the preserved DNA.

Analyses of the aDNA suggests that the Hissar pea most likely was an early domesticated pea, possibly the recently rediscovered so-called ‘tall’ pea (Pisum sativum elatius), found on the slopes of the Mount Kozjak, smome 150 kilometers from Hissar.

The peas and bitter vetches from Hissar were probably first collected by the inhabitants of Hissar or their unknown predecessors in the surrounding wild flora and then gradually cultivated. The Hissar pea could have had coloured flowers, pigmented seed coats and probably adapted to germinating in the autumn and being winter hardy[4].

[1] Tanno, Willcox: The origins of cultivation of Cicer arietinum L. and Vicia faba L: early finds from Tell el-Kerkh, north-west Syria, late 10th millennium BP in Vegetation History and Archaeobotany – 2006
[2] Aura et al: Plant economy of hunter-gatherer groups at the end of the last Ice age: plant macroremains from the cave of Santa Maira (Alacant, Spain) CA. 12000–9000 BC. in Vegetation History and Archaeobotany – 2005
[3] Medović et al: An archaeobotanical and molecular fairy tale about the early Iron Age Balkan princess and the charred pea in Pisum Genetics – 2010
[4] Smýkal et al: Molecular analysis of ancient DNA isolated from charred pea (Pisum sativum) seeds found at an early Iron Age settlement in southeast Serbia in Legume Perspectives – 2014. See here.