Identification of the Triticoid-type grains (Poaceae) from archaeobotanical assemblages in southwest Asia as Heteranthelium piliferum (Banks & Sol.) Hochst.

Alexander Weide,Hyunyoung Kim,Hojjat Darabi,Tobias Richter,Nicholas J Conard,Ann Frijda Schmidt,Amaia Arranz-Otaegui,Mohsen Zeidi,Michael Charles

doi:10.1007/s00334-020-00822-x

Abstract

The so-called Triticoid-type grains are known from several prehistoric sites in southwest Asia and their identification has long been unclear. They resemble the grains of wheats and researchers suggested they may represent an extinct Triticeae species, possibly closely related to wild crop progenitors. In this study we identify the Triticoid-type grains as Heteranthelium piliferum (Banks & Sol.) Hochst. and describe the key identification criteria. The identification is based on morphological analyses of modern and archaeological material from several grass species and was first achieved with well-preserved specimens from Early Neolithic Chogha Golan, Iran. We further examined the Triticoid-type grains from recently excavated samples from Early Neolithic Ganj Dareh, Iran, and archived samples from Late Chalcolithic and Late Bronze Age Tell Brak in northeast Syria, confirming their identification as H. piliferum. Based on the study of herbarium specimens at Royal Botanic Gardens Kew, London, we provide a detailed distribution map and review the species’ biology and ecological adaptations. Collected and cultivated herbarium specimens were analysed in order to understand the high phenotypic plasticity of the growth habit, its correlation with environmental variables and its relation to grain size. In order to understand the high morphological variability of the charred Triticoid-type grains from archaeological deposits, we assessed the effects of experimental carbonisation at different temperatures on grains of H. piliferum, Triticum dicoccum, T. thaoudar and Secale vavilovii. In light of the present study, we discuss the relevance of H. piliferum for reconstructing prehistoric subsistence strategies.

Highlights

Willem van Zeist and colleagues described an unidentified Poaceae grain type in their archaeobotanical report from the Early Neolithic site of Ganj Dareh in the central Zagros Mountains of Iran (van Zeist et al 1984)
We further examined Triticoid-type grains from recently excavated samples from Early Neolithic Ganj Dareh (Darabi et al 2019) and archived samples from Tell Brak in northeast Syria, dating from the Late Chalcolithic to the Late Bronze Age (McMahon et al 2007; Hald 2008), which confirmed their identification as H. piliferum
Emmer grains showed the most pronounced deformation and became swollen and rounded at 300 °C but retained their distinctive humped shape in lateral view (ESM 1 Fig. 4). These results suggest that we can reliably identify grains of H. piliferum and related Triticeae species charred at temperatures of up to 260 °C, while higher temperatures might complicate a separation of H. piliferum grains due to their strong deformation

Summary

Introduction

Willem van Zeist and colleagues described an unidentified Poaceae grain type in their archaeobotanical report from the Early Neolithic site of Ganj Dareh in the central Zagros Mountains of Iran (van Zeist et al 1984). Vegetation History and Archaeobotany (2021) 30:657–674 referred to the unidentified grains as ‘Triticoid type’ Riehl et al (2012, 2013) documented Triticoid-type grains from the Early Neolithic sites of East Chia Sabz and Chogha Golan in the central Zagros region of Iran, where this grain type is reported at a cluster of sites dating from the early 10th to the early 7th millennia bc The second published record derives from Early Dynastic layers at Tell Bderi in northeast Syria, dating to the 3rd millennium bc (van Zeist 1999/2000). Savard et al (2003) mentioned some grains resembling the Triticoid-types in the assemblage from Early Neolithic M’lefaat in northern Iraq, which they included in a Triticum boeoticum/Secale category. Riehl et al (2012, 2013) documented Triticoid-type grains from the Early Neolithic sites of East Chia Sabz and Chogha Golan in the central Zagros region of Iran, where this grain type is reported at a cluster of sites dating from the early 10th to the early 7th millennia bc

Results

Discussion

Conclusion