δ 13 C and δ 15 N from 14 C-AMS dated cereal grains reveal agricultural practices during 4300–2000 BC at Arslantepe (Turkey)

Chemotaxonomy of domesticated grasses: a pathway to understanding the origins of agriculture

“…FTIR spectra of the grass pollen grains (Fig. 2) show many of the same absorbance peaks as have been demonstrated in previous studies of pollen chemistry (Bagcıoglu et al, 2015(Bagcıoglu et al, , 2017Fraser et al, 2012Fraser et al, , 2014Jardine et al, 2015Julier et al, 2016;Watson et al, 2007;Zimmermann, 2010Zimmermann, , 2018Zimmermann and Kohler, 2014;Zimmermann et al, 2015aZimmermann et al, , b, 2016, including a broad OH band centred on 3300 cm −1 ; peaks representing lipids at 2925 cm −1 (asymmetric CHn stretching), 2850 cm −1 (asymmetric CHn stretching), 1740 cm −1 (C=O stretching) and 1465 cm −1 (CH 2 deformation); proteins at 1650 cm −1 (amide 1: C=O stretching) and 1550 cm −1 (amide II: combination of NH deformation and C−N stretching); and carbohydrates in the 1200 to 900 cm −1 region (C−O−C and C−OH stretching). The sporopollenin outer pollen wall (exine) is associated with peaks at 1160 and 860 cm −1 , which relate to aromatic ring vibrations (C−H deformation and stretching) (Bagcıoglu et al, 2015;Watson et al, 2007).…”

“…The sporopollenin outer pollen wall (exine) is associated with peaks at 1160 and 860 cm −1 , which relate to aromatic ring vibrations (C−H deformation and stretching) (Bagcıoglu et al, 2015;Watson et al, 2007). Previously identified aromatic peaks at 1600 and 1510 cm −1 (both C=C stretching) (Bagcıoglu et al, 2015;Jardine et al, 2015Watson et al, 2007) are not clearly present in the FTIR spectra and may be obscured by nearby protein-related peaks. Only subtle differences among the taxa are discernible in the spectra, most obviously in the 1200 to 900 cm −1 region that relates to carbohydrates (Fig.…”

“…These findings show that FTIR-based chemotaxonomy has considerable potential as a means of classifying Poaceae pollen to study grass domestication, and the spread of agriculture and landscape change over the last 10 kyr. The ability to generate species level count data from grass pollen would allow a much fuller use of the palynological record in archaeobotanical studies and would provide an additional tool to complement other lines of evidence such as grass seeds and chaff, starch grains and, more recently, DNA data from sedimentary deposits and ancient grains (Crowther et al, 2016;Fuller, 2007;Mascher et al, 2016;Piperno et al, 2004;Savard et al, 2006;Vignola et al, 2017;Willcox et al, 2007).…”

“…We used Fourier transform infrared (FTIR) microspectroscopy to generate chemical data, because it is an efficient method that has demonstrated success in pollen characterisation and classification studies (Bagcıoglu et al, 2015(Bagcıoglu et al, , 2017Bell et al, 2018;Bernard et al, 2015;Dell'Anna et al, 2009;Depciuch et al, 2018;Domínguez et al, 1998;Fraser et al, 2012Fraser et al, , 2014Gottardini et al, 2007;Jardine et al, 2015Julier et al, 2016;Lomax et al, 2008;Pappas et al, 2003;Steemans et al, 2010;Watson et al, 2007;Zimmermann, 2010Zimmermann, , 2018Zimmermann and Kohler, 2014;Zimmermann et al, 2015aZimmermann et al, , b, 2016. The pollen samples were picked onto ZnSe windows for FTIR analysis, which was carried out using a Thermo Scientific (Waltham, MA, USA) Nicolet Nexus FTIR bench unit, attached to a Continuum IR microscope fitted with an MCT-A liquid nitrogen-cooled detector, run in transmission mode using a Reflachromat 15× objective.…”

“…Redrawn from International Wheat Genome Sequencing Consortium (2014), with additional information from Petersen et al (2006Petersen et al ( ). 2006International Wheat Genome Sequencing Consortium, 2014;Marcussen et al, 2014;Mascher et al, 2016;Meyer and Purugganan, 2013;Petersen et al, 2006), controlled growth experiments (Cunniff et al, 2014;Preece et al, 2015Preece et al, , 2017Preece et al, , 2018, and archaeobotanical remains of grasses and grain processing (Crowther et al, 2016;Fuller, 2007;Piperno et al, 2004;Savard et al, 2006;Vignola et al, 2017;Willcox et al, 2007) have together provided a detailed picture of when and where different taxa were domesticated, including the hybridisation pathways that produced the modern domesticated types (Fig. 1b), and why certain species may have been selected for cultivation over others.…”