Earliest Use of Birch Bark Tar in Northwest China: Evidence from Organic Residues in Prehistoric Pottery at the Changning Site

Vegetation History and Archaeobotany https://doi.org/10.1007/s00334-018-0694-7

ORIGINAL ARTICLE

Earliest use of birch bark tar in Northwest China: evidence from organic residues in prehistoric pottery at the Changning site

Huiyun Rao1 · Qianqian Wang2 · Xiaoyan Ren2 · Zhaoxia Zhang1 · Wanxia Huang3 · Qingxi Yuan3 · Xiaochenyang Jiang1,4 · Yimin Yang4

Received: 7 May 2017 / Accepted: 30 July 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018

Abstract The analysis of organic residues in pottery can provide abundant information on the lives of ancient people, including the natural resources consumed, the techniques applied, the functions of pottery, and so on. In this paper, a variety of methods, including FT-IR (Fourier transform infrared spectroscopy), GC–MS (gas chromatography-mass spectrometry), SEM (scanning electron microscopy) and SR-μCT (synchrotron radiation micro-computed tomography), have been employed to characterize the carbonized residues from an amphora, unearthed from the Changning site, Qinghai Province, Northwest China. The pottery residues were identified as birch bark tar, so ancient people in China could have used the particular local plant resources, birch bark, to produce tar as early as the Qijia cultural period (c. 4,000–3,500 bp). The birch bark tar could have been used to make composite tools discovered at the Changning site, and the amphora has probably been used for tar production. This, to our knowledge so far, is the earliest evidence for the use of birch bark tar in China. Due to the special geographical location of the Gansu-Qinghai Region, and the transition of subsistence strategy during the Qijia cultural period, the production and utilization of birch bark tar could not rule out the possibility of western influence, which needs further evidence.

Keywords Birch bark tar · Pottery function · Carbonized residues · Qijia culture

Introduction 1999a; Mottram et al. 1999), dairying (Copley et al. 2003; Evershed et al. 2008; Salque et al. 2013), brewing (Correa- Pottery wares, of different types and functions, are amongst Ascencio et al. 2014) and dyeing (James et al. 2009), have the most common artifacts found at archaeological sites been conducted in pottery vessels, and organic matter pre- across China since the Late Glacial (Kuzmin 2006). A served as carbonized surface residues or absorbed residues variety of processes, such as cooking (Dudd and Evershed in porous ceramic matrices. The characterization of organic residues in pottery can provide valuable information about Communicated by J. Kitagawa. the natural resources consumed or used by ancient people, the techniques applied to prepare all these products and also * Yimin Yang the functions of related pottery. [email protected] Pottery residues have been observed and studied since 1 Key Laboratory of Vertebrate Evolution and Human Origins the end of the 19th century, and research in the area has of Chinese Academy of Sciences, Institute of Vertebrate greatly expanded in recent decades due to improvements in Paleontology and Paleoanthropology, Chinese Academy analytical tools, such as chromatographic and mass spec- of Sciences, Beijing 100044, People’s Republic of China trometric techniques (Evershed et al. 1991; Charters and 2 Qinghai Provincial Institute of Cultural Relics Evershed 1997; Regert et al. 2001; Stott et al. 2003; Hansel and Archaeology, Xining 810007, People’s Republic of China and Evershed 2009; Correa-Ascencio and Evershed 2014). 3 Institute of High Energy Physics, Chinese Academy Fourier transformed infrared spectroscopy (FT-IR) and of Sciences, Beijing 100049, People’s Republic of China mass spectrometric methods [direct inlet electron ionization 4 Department of Archaeology and Anthropology, University mass spectrometry (DI-MS), direct temperature-resolved of Chinese Academy of Sciences, Beijing 100049, mass spectrometry (DT-MS), pyrolysis-mass spectrometry People’s Republic of China

Vol.:(0123456789)1 3 Vegetation History and Archaeobotany

(Py-MS) etc.] have been employed as preliminary analyses microscopic observations (scanning electron microscopy, of organic residues and could provide the general chemi- SEM, and synchrotron radiation micro-computed tomog- cal information of residues to guide further investigations raphy, SR-μCT), and analytical techniques (FT-IR and (Oudemans and Boon 1991; McGovern et al. 1996; Regert GC–MS). and Rolando 2002; Oudemans et al. 2007; Kaal et al. 2014). Because of their hydrophobicity and thermal resistance, lipids are more likely to be preserved in pottery, and gas Site description chromatography-mass spectrometry (GC–MS) is the most commonly used technique for lipid analysis (Evershed Within the valley of the Huangshui River, the Changn- et al. 1990, 2002; Evershed 2008; Heron et al. 2016). With ing site is situated on the second terrace of the Beichuan the identification of specific biomarkers, a wide range of River, which is approximately 100 km east of Qinghai lipid commodities have been revealed, including animal Lake, Northwest China (Fig. 1). The valley of the Huang- fats (Evershed et al. 2002; Poulain et al. 2016), plant oils shui River has a semi-arid plateau continental climate (Romanus et al. 2007; Dunne et al. 2016), beeswax (Ever- and diverse ecological landscapes, which include desert shed et al. 1997; Heron et al. 2015), epicuticular leaf waxes steppe, steppe, meadow steppe and forest, alpine meadow, (Charters and Evershed 1997; Dunne et al. 2016), birch glaciers, and so on (Wang 2015). Combining fauna with bark tar (Lucquin et al. 2007; Mitkidou et al. 2008), pine pollen data, it can be inferred that the environmental con- resin (Colombini et al. 2005; Jerkovic et al. 2011) and so ditions of the Changning site were similar to today’s tem- on. Recently, gas chromatography-combustion-isotope ratio perate steppe-forest landscape (Li 2012). mass spectrometry (GC-C-IRMS) has also been applied to In 2006, a total area of 3,000 m2 was unearthed, includ- calculate isotope ratios of individual fatty acids in organic ing 15 houses, 150 pits and cellars, and 6 tombs. Vari- residues, and has enabled the differentiation of ruminant ous artifacts were found, such as pottery wares, stone adipose, ruminant dairy fats, non-ruminant adipose, fresh- tools, jade articles, bronze vessels, bone implements and water and marine resources (Evershed et al. 2008; Craig so on. Storage and cooking vessels were the main pot- et al. 2011; Heron et al. 2015; Nieuwenhuyse et al. 2015; tery collections (QPICRA 2006). Besides artifacts, ani- Oras et al. 2017). Immunological methods and proteomic mal bones (sheep, cattle, pig, horse, dog etc.) and plant approaches have been conducted to identify the proteina- remains (Setaria italica—foxtail millet, Panicum mili- ceous residues (Craig and Collins 2000; Wiktorowicz et al. aceum—broomcorn millet, Triticeae tribe etc.) were also 2017). discovered, indicating that both agriculture and animal The Changning site (dated to approximately husbandry have played important roles in the Changning 4,000–3,500 bp; QPICRA 2006) is a large settlement of people’s lives (Li 2012; Li et al. 2013; Wang 2015). As a the Qijia culture in Qinghai Province, Northwest China large settlement of the Qijia culture, the Changning site (QPICRA 2006; Li 2012). A two-handled amphora was developed over a transition period between agriculture and unearthed in a pit at this site, with black charred residues pastoralism, and also within an intermediate period from inside. In this paper, an interdisciplinary methodology has the Neolithic era to the Bronze Age, which is an important been developed to analyse the residues in this amphora, time span for the formation of Chinese civilization (QPI- in order to identify their nature and origins and to reveal CRA 2006; Li 2012). the functions of related pottery. This method comprises

Fig. 1 Location of the Changn- ing site, Datong County, Qing- hai Province, Northwest China

1 3 Vegetation History and Archaeobotany

Materials and methods

Fragments of a two-handled amphora with a red coarse clay body were unearthed from pit H34 at the Changning site. The wall thickness was approximately 1 cm. Figure 2 shows the inner and outer surfaces of two shards S1 and S2 of this amphora. Black residues with a variable thickness were observed on the inner surfaces of these shards (Fig. 2b, d), while black soot traces were detected near the rim on the outer surfaces of the shards (Fig. 2a, c). At the bottom of the amphora, some brown or black charred lumps were found. Fig. 3 The archaeological samples analysed; a the inner surface of The black residues adhering to the inner surface of shard S3 shard S3, where surface residues were sampled (sample label ISR). were scraped with a sterilized blade and collected for further The outer surface residues were also sampled as the control sample (labeled as OSR). Scale bar 4 cm. b The charred lumps (sample label analyses (labelled as ISR) (Fig. 3a), while the outer surface CL), which were sampled from the bottom of the amphora. Scale residues were collected in the same manner as the control bar 1 cm sample (labelled as OSR). Charred lumps were also sampled (labelled as CL) (Fig. 3b). Fresh modern birch bark (Betula platyphylla, plant No. UCAS 20140102, labelled as MB1) Rao et al. (2017).The pottery residue samples and modern was collected as a reference sample from the campus of Uni- birch bark reference sample were further analysed with a versity of Chinese Academy of Sciences. To obtain the mod- 7890A gas chromatograph and a 5975C mass detector in ern charred reference sample (labelled as MB2), the birch 70 eV electron impact mode (GC–MS). The procedure was bark was heated in a muffle furnace at 250 °C for 4 days. modified from procedures used by Regert et al. (2003b), Charred lumps (CL) and inner surface residues (ISR) Mitkidou et al. (2008) and Rao et al. (2017). In brief, CL, were analysed with a Nicolet 6700 (Thermo Scientific) ISR, OSR and MB1 were extracted using chloroform/meth- FT-IR spectrometer. The detailed procedure is described in anol (2:1 v/v), derivatised by BSTFA (bis(trimethylsilyl) trifluoroacetamide with 1% trimethylchlorosilane) and re- dissolved with CH 2Cl2 for the GC–MS analysis. The oven temperature program was as follows: initial temperature 50 °C for 2 min; increased to 150 °C (2 min) at 10 °C/min; then increased to 290 °C at 4 °C/min; 290 °C was main- tained for 20 min. An analytical blank was also prepared and run along with the samples under the same experimental conditions for contamination control. An archaeological CL and modern charred birch bark (MB2) were scanned by SEM. The sample was fixed on the object mount by a conducting glue (graphite-based) and coated with gold. ZEISS EVO 25 scanning electron microscopy was used with an electron beam of 10 keV. A CL was scanned by SR-μCT in a 4W1A beamline in the Beijing Synchrotron Radiation Facility (BSRF), Beijing, China. The X-ray source energy used was 12 keV and the CCD detector (photonic science VHR16 M) had a space resolution of 7.4 μm.

Results and discussion

The identification of birch bark tar

The FT-IR spectra of the pottery residue samples were domi- Fig. 2 The outer and inner surfaces of the amphora shards; a and b nated by absorption bands of organic matter, especially the show the outer and inner surfaces of shard S1, respectively; c and d show the outer and inner surfaces of shard S2, respectively. Scale CL discovered at the bottom of the amphora (Fig. 4). Com- bar 10 cm pared with the published data (Bellamy 1980; Schrader

1 3 Vegetation History and Archaeobotany

Fig. 4 FT-IR spectrum of CL. The specific peaks attributed to organic matter, probably birch bark tar

2008; Cîntă-Pînzaru et al. 2012; Silverstein et al. 2014), the absorption peaks could be assigned to specific functional Fig. 5 Partial gas chromatogram of a MB1 (modern birch bark); b CL (charred lumps) and c ISR (inner surface residues); showing a series groups and chemical components, which are summarized in of triterpenoid biomarkers derived from birch bark. d is a partial Table 1. These peaks have also been found in ancient birch enlarged detail of a. 1, lupa-2, 20(29)-diene; 2, lupa-2,20(29)-dien- bark or birch bark tar published elsewhere and implied that 28-ol; 3, allobetul-2-ene; 4, lupenone; 5, lupeol; 6, betulone; 7, betu- the CL could have derived from birch bark (Bosquet et al. lin; 8, betulinic acid. The hydroxyl triterpenoids were all identified as their TMS derivatives 2001; Regert and Vacher 2001; Regert et al. 2003a; Regert 2007; Trąbska et al. 2011; Pietrzak and Langer 2012; Rao et al. 2017). The specific band at 886 cm−1 also indicated considered as specific constituents in fresh birch bark (Cui that the CL was rather birch bark tar than pine resin (Pietrzak and Zheng 1994), while the other three (lupa-2,20(29)-diene, and Langer 2012), which would be further confirmed by lupa-2,20(29)-dien-28-ol and allobetul-2-ene) were regarded GC–MS analysis. as indicators of thermal treatment and degradation (Reu- A series of triterpenoid biomarkers were detected by nanen et al. 1993; Aveling and Heron 1998; Regert 2004). GC–MS in MB1, CL and ISR (Fig. 5). These biomarkers None of these biomarkers were detected in the analytical were identified based on mass spectra as well as retention blank and the control sample (OSR).The results showed that time, which were searched against the NIST 08 Mass Spec- the discovered pottery residues were products of birch bark tral Library and also compared with modern birch bark ref- with a thermal treatment, which confirmed the preliminary erence and published data (Table 2) (Charters et al. 1993; result of FT-IR. Reunanen et al. 1993; Colombini and Modugno 2009; Rao With increasing duration and intensity of pyrolytic treat- et al. 2017). Of all the eight biomarkers, five components ment, the proportions of different biomarkers change (Koller (betulin, betulin acid, lupeol, betulone and lupenone) were et al. 2001). Regert et al. (2003b) have calculated a variable named “MD/BioM”, defined as the ratio between the main original biomarkers (lupeol and betulin) and the degradation Table 1 The observed IR bands (cm −1) of charred lumps (CL) and markers (lupa-2,20(29)-diene, lupa-2,20(29)-dien-28-ol and their assignments allobetul-2-ene). In their publication (Regert et al. 2003b), IR bands (cm −1) Assignments three different distribution patterns were classified, i.e. biomarkers predominant (MD/BioM < 0.5), similar amounts of 3,421 ν (O–H) biomarkers and degradation markers (0.5< MD/BioM< 1.5) 2,922; 2,851 νas (C–H), νs (C–H) and degradation markers predominant (MD/BioM > 1.5). 1,705 ν (C=O) After quantifying the relative percentages of the identified 1,597 ν (C=C) triterpenoids, the MD/BioM values of our ancient CL and 1,456; 1,375 δ (CH3) + δ(CH2) ISR were calculated as 3.76 and 2.08 respectively, indicating 1,173 ν (C–C) the predominance of degradation products. Thus it implied 886 ω (C–H) that birch bark has been heated to some extent (over 400 °C ν, stretching; δ, bending; ω, out-of-plane bending; as, asymmetrical; or for a long time) to make this product in the amphora s, symmetrical (Dudd and Evershed 1999b; Koller et al. 2001).

1 3 Vegetation History and Archaeobotany

Table 2 The biomarker Biomarkers CL ISR MB1 Ancient birch Modern birch Ancient composition of archaeological barka bark tarb birch bark samples and birch bark (tar) tarc references Lupa-2, 20(29)-diene X X X X Lupa-2,20(29)-dien-28-ol X X X X X Allobetul-2-ene X X X Lupenone X X X X X Lupeol X X X X X X Betulone X X X X Betulin X X X X X X Allobetulinol X Betulinic acid X X

CL charred lumps, ISR inner surface residues, MB1 modern birch bark reference a Rao et al. (2017) b Mitkidou et al. (2008) c Regert et al. (2003b)

Birch bark could have been heated to produce birch bark material with similar density, except for some pores (Fig. 7). tar, which was usually used as an adhesive in Europe (Char- Because of their size and number, these pores did not belong ters et al. 1993; Roebroeks and Villa 2011), or charred birch to birch bark structure and would have been formed dur- bark, which was a type of important Chinese traditional ing the production and utilization of birch bark tar. Thus it medicine (Li 1991). In order to differentiate both birch bark could be inferred that the CL were birch bark tar (rather than products and obtain more information about the process charred birch bark), which could be obtained by high-tem- technology, an archaeological CL and modern charred birch perature treatment (definitely higher than the experimental bark reference sample (MB2) were chosen for SEM observa- carbonization temperature of 250 °C) or repeated/lengthy tion (Fig. 6). Although MB2 has been heated at 250 °C for heating treatment. 4 days, the primary plant structure was clearly visible, with Birch bark tar was usually used as an adhesive in ancient numerous cork layers which were composed of two differ- Europe and could be traced back to the Middle Palaeolithic ent cell types (Fig. 6b). The different cellular structures of (at least 200,000 years ago) (Roebroeks and Villa 2011). these two cell types were attributed to their different chemi- Birch bark tar was used for hafting composite tools (Roe- cal constituents, as the thicker walled cells were more heav- broeks and Villa 2011), repairing pottery (Charters et al. ily suberized (Orsini et al. 2015). As for the archaeological 1993), coating or waterproofing pottery (Regert et al. CL, only the compact homogeneous structure was observed 2003b), decorating pottery (Trąbska et al. 2011; Jakucs (Fig. 6a), indicating a complete tar distillation that trans- and Sándorné Kovács 2012) etc. In China, although plant formed the bark into an amorphous matrix (Pawlik 2004). adhesives, including lacquer, plant oils, starch, gum, resin, The CT image of the cross section of a CL also revealed bark tar (from Ilex integra) and various others, have been that the main part of the lump was homogeneous organic recorded in the literature or identified on archaeological

Fig. 6 The SEM images of a CL (charred lumps) and b MB2 (modern charred birch bark). There were two different cell types, one with narrower radial dimension and thicker cell walls. Scale bar = 0.2 mm

1 3 Vegetation History and Archaeobotany

The ‘double-pot’ method is conducted with one pot placed on top of another; the pot on top (retort) is pierced with holes in the bottom, filled with birch bark, covered with a lid and sealed with clay. These pots are put in a pit, where a fire is lit on top to transform the bark to tar dripping into the pot underneath (receptacle) (Evans and Heron 1993; Jauch 1994; Hennius et al. 2005; Fuchs and Wahl 2013). While the use of birch bark tar is well reported in various archaeological contexts (Grünberg 2002; Lucquin et al. 2007; Mitki- dou et al. 2008; Roebroeks and Villa 2011), the discovered remains in association with its production are quite rare, especially during the prehistoric period. To our knowledge, the earliest retort was unearthed at an Early Bronze Age site in Eastern Hungary (Jakucs and Sándorné Kovács 2012). It is necessary to find the retort on top to deduce the amphora as a receptacle more confidently. Unfortunately, no Fig. 7 The cross section image of a CL obtained by SR-μCT. Scale pottery with pierced holes in the bottom has been reported bar = 0.5 mm. The image indicated homogeneous organic material with some pores at the Changning site up to now. But at other Qijia cultural sites in the adjacent Gansu Province, this type of pottery was discovered and named as ‘Zeng’, which is a part of artifacts (Chen 2003; Wei et al. 2011; Rao et al. 2015), birch the composite cooking utensil ‘Yan’ (Xie 2002). ‘Yan’ is a bark tar has never been mentioned. This is the first time that kind of steamer with ‘Zeng’ on top of another pottery ves- birch bark tar has been identified in China, which improves sel ‘Li’; water is added to the ‘Li’ and boiled down to give our understanding of Chinese adhesives. Composite tools rise to steam, which heats up the food in the ‘Zeng’ through made of bones and microblades were also discovered at the the holes in its bottom (Zhang 2002). Actually Yan-shaped Changning site (QPICRA 2006; Wang 2015), and birch bark pottery has been discovered at more than 70 sites all over tar might have played a role in manufacturing these tools, China since the Middle Neolithic period, and their functions but this needs further confirmation. are sometimes doubtful (Shi 1993; Fu 2014). With organic residues analysis, we may provide significant information The function of the amphora on the pottery function, and also have a chance of finding a retort for birch bark tar production. Understanding pottery function is usually very difficult as there is no one-to-one correlation between use and the The possible origin of birch bark tar morphology or physical properties of a vessel (Rice 1987). Combining the morphological observations with the organic Betula (birch), with between 50 and 60 species of broad- residue results, we intend to make a better interpretation leaved deciduous trees or shrubs, is the largest genus in the of the function of this amphora. Birch bark tar has been family of Betulaceae (Li and Skvortsov 2013). Betulaceae identified in this amphora, which could be related to pot- first appeared in the Late Cretaceous and began to flourish in tery utilization (adhesive production or storage), produc- the Tertiary (Chen 1994). After originating in central China, tion (coating or decoration) or repair (Regert 2007). Based Betulaceae spread westwards to Europe and were distributed on the distribution and morphology of the pottery residues mainly in the temperate zone of the Northern Hemisphere and charred lumps, the function of this amphora is probably (Chen 1994). In China, 32 species (14 endemic) of birch associated with the production or storage of birch bark tar are mostly found in the northeast, northwest and southwest (Regert 2007). Amphorae are usually used for storage, but mountain areas (Li and Skvortsov 2013). Five species of the coarse property of this amphora makes it also suitable Betula, deciduous trees or shrubs, naturally grow in Qing- for heating (Skibo 2013). The soot traces, detected on the hai Province (Northwest China), among which one species outer surface near the rim of the amphora (Figs. 2a, c), also (B. albosinensis) prevails around Datong County where the imply that this amphora could have been heated, probably archaeological site is located (NWIPB and ECFQ 1997). from the upper part near the rim. All these characteristics of Ancient textual research has indicated the presence of broad- the amphora are, to some degree, consistent with those of the leaved deciduous forest (including birch) around the vicinity receptacles that are used for the collection of birch bark tar of the Changning site during the 18th century (Wen and He in the ‘double-pot’ method, a typical method of birch bark 1979). Fauna and pollen data have also revealed a temper- tar production. ate steppe-forest landscape for the Changning site, which

1 3 Vegetation History and Archaeobotany was favourable for the growth of Betula (Li 2012). What is to improve our understanding of the process technology and more, direct evidence of Betula pollen has also been found origin of birch bark tar in Northwest China. in the Qijia cultural layers of the Changning palaeosol section (Dong et al. 2012) and adjacent cores of sediment from Acknowledgements The authors would like to thank Matthew Collins, Alexandre Lucquin and Shannon Croft from University of York for Qinghai Lake (Liu et al. 2002). giving professional comments on the identification of birch bark tar. Plentiful Betula resources could be found around the This study was supported by the Strategic Priority Research Program of Changning site, even North China (Chen 1994; Li and Chinese Academy of Sciences (XDB26000000), the National Natural Skvortsov 2013), and they have been well exploited by Science Foundation of China (Grant Nos. 41702186 and 41472145), National Young Top-Notch Talent Support Program in China and ancient people. For example, at the contemporary Liuwan Youth Innovation Promotion Association of CAS. cemetery, which is approximately 100 km southeast of the Changning site and belongs to the same Huangshui region, Betula wood and a birch bark quiver have been discovered in tombs (Wen 2006; Liu 2010). Birch bark has also been long References exploited in North China with abundant historical records and plenty of birch bark artifacts discovered at archaeolog- Aveling E, Heron C (1998) Identification of birch bark tar at the Meso- ical sites, known for “birch bark culture” (Yu 2006; Yin lithic site of Star Carr. Ancient Biomol 2:69–80 2009). Thus, the birch bark tar identified at the Changning Bellamy LJ (1980) The infra-red spectra of complex molecules, 2 edn, Betula vol 2. Chapman and Hall, London and New York site could have been produced using local resources. Bosquet D, Regert M, Dubois N, Jadin I (2001) Identification de brai Although this is the first birch bark tar found in China, it de bouleau sur quatre vases du site rubané de Fexhe-le-Haut- was frequently produced and used in ancient Europe since Clocher « Podrîl’Cortri». Prem Résult Notae Praehist 21:119–127 the Middle Palaeolithic (Regert 2004; Roebroeks and Villa Charters S, Evershed RP (1997) Simulation experiments for determin- ing the use of ancient pottery vessels: the behaviour of epicuticu- 2011). It should be considered where the process technol- lar leaf wax during boiling of a leafy vegetable. J Archaeol Sci ogy of birch bark tar originated, locally or externally. The 24:1–7 Gansu-Qinghai area is amongst the interlocking terrain of Charters S, Evershed RP, Goad LJ, Heron C, Blinkhorn P (1993) Iden- agriculture and nomadism in Northwestern China, and also tification of an adhesive used to repair a Roman jar. Archaeometry 35:91–101 along the Hexi Corridor, where communication between Chen D (2003) Chinese adhesives and their application in remote ages. East and West occurred frequently (Yang 2004; Han 2005). China Hist Mater Sci Technol 24:359–365 During the Qijia cultural period (c. 4,000–3,500 bp), which Chen Z (1994) Phylogeny and phytogeography of the Betulaceae is a transition period from the Neolithic era to the Bronze (cont.). Acta Phytotax Sin 32:101–153 Cîntă-Pînzaru S, Dehelean CA, Soica C, Culea M, Borcan F (2012) Age, the subsistence strategy transitioned gradually from Evaluation and differentiation of the Betulaceae birch bark spe- agriculture to mainly pastoralism (Xie 2002). Located in this cies and their bioactive triterpene content using analytical FT- particular geographical unit during this key period, many vibrational spectroscopy and GC-MS. Chem Cent J 6:67 remains influenced by western culture have been discov- Colombini MP, Giachi G, Modugno F, Ribechini E (2005) Charac- terisation of organic residues in pottery vessels of the Roman ered at the Changning site, such as cattle, sheep, wheat and age from Antinoe (Egypt). Microchem J 79:83–90. https://doi. bronze (QPICRA 2006; Li 2012; Li et al. 2013; Wang 2015). org/10.1016/j.microc.2004.05.004 Perhaps the process technology of birch bark tar is another Colombini MP, Modugno F (2009) Organic mass spectrometry in art marker of Eurasian communication in this area. However, and archaeology. Wiley, Chichester Copley MS et al (2003) Direct chemical evidence for widespread dairy- more evidence is needed to support or deny this assumption. ing in prehistoric Britain. Proc Natl Acad Sci USA 100:1,524– 1,529. https://doi.org/10.1073/pnas.0335955100 Correa-Ascencio M, Evershed RP (2014) High throughput screening of Conclusions organic residues in archaeological potsherds using direct acidified methanol extraction. Anal Methods 6:1,330–1,340 Correa-Ascencio M, Robertson IG, Cabrera-Cortés O, Cabrera-Castro In this study, a multidisciplinary approach, including SEM, R, Evershed R (2014) Pulque production from fermented agave SR-μCT, FT-IR and GC–MS, has been employed to iden- sap as a dietary supplement in prehispanic Mesoamerica. Proc tify birch bark tar in a prehistoric pot from the Changning Natl Acad Sci USA 111:14,223–14,228. https://doi.org/10.1073/ pnas.1408339111 site, Northwest China. This is the first time that birch bark Craig OE, Collins MJ (2000) An improved method for the immunologi- tar has been detected in China, which opens a new window cal detection of mineral bound protein using hydrofluoric acid and on understanding the ancient Changning people’s technol- direct capture. J Immunol Methods 236:89–97 ogy. We have discussed the possible process for producing Craig OE, Steele VJ, Fischer A et al (2011) Ancient lipids reveal con- tinuity in culinary practices across the transition to agriculture in adhesive (distilling of birch bark in pottery), and where this Northern Europe. Proc Natl Acad Sci USA 108:17,910–17,915. technology might come from. However, we still need to ana- https://doi.org/10.1073/pnas.1107202108 lyse more samples around this area, including the residues in Cui Y, Zheng Z (1994) The chemical composition of the birch bark. J ‘Zeng’, and adhesive observed on archaeological artifacts, Northeast Forestry Univ 22:53–60

1 3 Vegetation History and Archaeobotany

Dong G, Jia X, An C, Chen F, Zhao Y, Tao S, Ma M (2012) Mid- James MA et al (2009) High prestige Royal Purple dyed textiles Holocene climate change and its effect on prehistoric cultural from the Bronze Age royal tomb at Qatna, Syria. Antiquity evolution in eastern Qinghai Province, China. Quat Res 77:23–30 83:1,109–1,118 Dudd SN, Evershed RP (1999a) Evidence for varying patterns of Jauch V (1994) Eine römische Teersiederei im antiken Tasgetium- exploitation of animal products in different prehistoric pottery Eschenz. Archéol Suisse 17:111–119 traditions based on lipids preserved in surface and absorbed resi- Jerkovic I, Marijanovic Z, Gugic M, Roje M (2011) Chemical pro- dues. J Archaeol Sci 26:1,473–1,482 file of the organic residue from ancient amphora found in the Dudd SN, Evershed RP (1999b) Unusual triterpenoid fatty acyl ester Adriatic Sea determined by direct GC and GC-MS analysis. components of archaeological birch bark tars. Tetrahedron Lett Molecules 16:7,936–7,948. https://doi.org/10.3390/molec ules1 40:359–362. https://doi.org/10.1016/s0040-4039(98)02311-9 6097936 Dunne J, Mercuri AM, Evershed RP, Bruni S, di Lernia S (2016) Ear- Kaal J, Lantes-Suárez O, Martínez Cortizas A, Prieto B, Prieto Mar- liest direct evidence of plant processing in prehistoric Saharan tínez MP (2014) How useful is pyrolysis-GC/MS for the assess- pottery. Nat Plants 3:16,194 ment of molecular properties of organic matter in archaeological Evans K, Heron C (1993) Glue, disinfectant and chewing gum: natural pottery matrix? An exploratory case study from North-West Spain. products chemistry in archaeology. Chem Ind 12:446–449 Archaeometry 56:187–207. https://doi.org/10.1111/arcm.12057 Evershed RP (2008) Organic residue analysis in archaeology: the Koller J, Baumer U, Mania D (2001) High-tech in the Middle Palaeo- archaeological biomarker revolution. Archaeometry 50:895–924. lithic: neandertal-manufactured pitch identified. Eur J Archaeol https://doi.org/10.1111/j.1475-4754.2008.00446.x 4:385–397 Evershed RP, Dudd SN, Copley MS et al (2002) Chemistry of archae- Kuzmin YV (2006) Chronology of the earliest pottery in East Asia: ological animal fats. Acc Chem Res 35:660–668. https://doi. progress and pitfalls. Antiquity 80:362–371 org/10.1021/Ar000200f Li L (2012) A study on animal exploitation of Changning site, Qing- Evershed RP, Heron C, Goad LJ (1990) Analysis of organic resi- hai Province, Northwestern China. Master thesis. Jilin University, dues of archaeological origin by high-temperature gas chroma- Changchun, China tography and gas chromatography mass spectrometry. Analyst Li M, Yang X, Ge Q, Ren X, Wan Z (2013) Starch grains analysis of 115:1,339–1,342 stone knives from Changning site, Qinghai Province, Northwest Evershed RP, Heron C, Goad LJ (1991) Epicuticular wax components China. J Archaeol Sci 40:1,667–1,672 preserved in potsherds as chemical indicators of leafy vegetables Li P, Skvortsov AK (2013) Betulaceae. In: FOCEC (ed) Flora of China. in ancient diets. Antiquity 65:540–544 Science Press, Beijing Evershed RP, Payne S, Sherratt AG et al (2008) Earliest date for milk Li S (1991) Compendium of materia medica (Bencao, Gangmu). use in the Near East and southeastern Europe linked to cattle herd- Shanghai Chinese Classics Publishing House, Shanghai ing. Nature 455:528–531. https://doi.org/10.1038/nature07180 Liu B (2010) From Liuwan Cemetery to the prehistorical archaeologi- Evershed RP, Vaughan SJ, Dudd SN, Soles JS (1997) Fuel for thought? cal research in Hehuang Region. Sanqing Publishing House, Xi’an Beeswax in lamps and conical cups from Late Minoan Crete. Liu X, Shen J, Wang S, Yang X, Tong G, Zhang E (2002) A 16000-year Antiquity 71:979–985 pollen record of Qinghai Lake and its paleoclimate and paleoen- Fu L (2014) Research on yan-shaped pottery steamers. J Natl Mus vironment. Chin Sci Bull 47:1,931–1,936 China 3:6–19 Lucquin A, March RJ, Cassen S (2007) Analysis of adhering organic Fuchs C, Wahl J (2013) Kaugummi oder Werkstoff? Birkenpechstücke residues of two “coupes-à-socles” from the Neolithic funerary site aus der Pfahlbausiedlung Hornstaad-Hörnle am Bodensee. Denk- “La Hougue Bie” in Jersey: evidences of birch bark tar utilization. malpfl Baden-Württemberg 4(2013):240–245 J Archaeol Sci 34:704–710 Grünberg JM (2002) Middle Palaeolithic birch-bark pitch. Antiquity McGovern PE, Glusker DL, Exner LJ (1996) Neolithic resinated wine. 76:15–16 Nature 381:480–481 Han M (2005) Formation of the interlocking belt of agriculture and Mitkidou S, Dimitrakoudi E, Urem-Kotsou D, Papadopoulou D, Kot- husbandry and climate change in ancient North China. Archaeol- sakis K, Stratis JA, Stephanidou-Stephanatou I (2008) Organic ogy 10:57–68 residue analysis of Neolithic pottery from North Greece. Micro- Hansel FA, Evershed RP (2009) Formation of dihydroxy acids from chim Acta 160:493–498 Z-monounsaturated alkenoic acids and their use as biomark- Mottram HR, Dudd SN, Lawrence GJ, Stott AW, Evershed RP (1999) ers for the processing of marine commodities in archaeological New chromatographic, mass spectrometric and stable isotope pottery vessels. Tetrahedron Lett 50:5,562–5,564. https://doi. approaches to the classification of degraded animal fats preserved org/10.1016/j.tetlet.2009.06.114 in archaeological pottery. J Chromatogr A 833:209–221 Hennius A, Svensson J, Ölund A, Göthberg H (2005) Kol och tjära— Nieuwenhuyse OP, Roffet-Salque M, Evershed RP, Akkermans Arkeologi I norra Upplands skogsmarker: Undersokningar for E PMMG, Russell A (2015) Tracing pottery use and the emergence 4. Upplandsmuseet, Uppsala of secondary product exploitation through lipid residue analysis at Heron C, Craig OE, Luquin A, Steele VJ, Thompson A, Piličiauskas Late Neolithic Tell Sabi Abyad (Syria). J Archaeol Sci 64:54–66. G (2015) Cooking fish and drinking milk? Patterns in pottery use https://doi.org/10.1016/j.jas.2015.10.002 in the southeastern Baltic, 3,300–2,400 cal BC. J Archaeol Sci NWIPB, ECFQ (1997) Flora Qinghaiica, vol 1. Qinghai People’s Pub- 63:33–43. https://doi.org/10.1016/j.jas.2015.08.002 lishing House, Xining Heron C, Shoda S, Barcons AB et al (2016) First molecular and iso- Oras E, Lucquin A, Lõugas L, Tõrv M, Kriiska A, Craig OE (2017) topic evidence of millet processing in prehistoric pottery vessels. The adoption of pottery by north-east European hunter-gatherers: Sci Rep 6:38,767 evidence from lipid residue analysis. J Archaeol Sci 78:112–119. Jakucs J, Sándorné Kovács J (2012) Északkelet-magyarországi és https://doi.org/10.1016/j.jas.2016.11.010 északnyugat-romániai középső neolit festett kerámiák festé- Orsini S, Ribechini E, Modugno F, Klügl J, Di Pietro G, Colombini kanyagának azonosítása Fourier-transzformációs Infravörös MP (2015) Micromorphological and chemical elucidation of the Spektrofotometriai (FTIR) módszerrel. In: Kreiter A, Petö Ak, degradation mechanisms of birch bark archaeological artefacts. Tugya BT (eds) Környezet–Ember–Kultúra. Magyar Nemzeti Herit Sci 3:1–11 MúzeumNemzeti Örökségvédelmi Központ, Budapest, pp Oudemans TFM, Boon JJ (1991) Molecular archaeology: analysis of 307–316 charred (food) remains from prehistoric pottery by pyrolysis-gas

1 3 Vegetation History and Archaeobotany

chromatography/mass spectrometry. J Anal Appl Pyrol 20:197– Roebroeks W, Villa P (2011) On the earliest evidence for habitual use 227. https://doi.org/10.1016/0165-2370(91)80073-h of fire in Europe. Proc Natl Acad Sci USA 108:5,209–5,214 Oudemans TFM, Eijkel GB, Boon JJ (2007) Identifying biomolecular Romanus K, Poblome J, Demarcke M, Degryse P, Jacobs P, De Vos origins of solid organic residues preserved in Iron Age Pottery D, Waelkens M (2007) Assessing the content of local/regional using DTMS and MVA. J Archaeol Sci 34:173–193. https://doi. fabric 4 amphorae from Sagalassos, SW Turkey. In: Poblome J, org/10.1016/j.jas.2006.04.007 Monsieur P, Vermeulen F, Waelkens M (eds) From amphorae to Pawlik AF (2004) Identification of hafting traces and residues by modelling the late Roman economy (International ROCT Work- scanning electron microscopy and energy-dispersive analysis of shop, 5-6 December 2005, Ghent). FACTA; A Journal of Roman X-rays. In: Walker EA, Wenban-Smith F, Healy F (eds) Lithics in Material Culture Studies, Supplement 1. Pisa-Rome Action: papers from the conference lithic studies in the year 2000. Salque M, Bogucki PI, Pyzel J, Sobkowiak-Tabaka I, Grygiel R, Szmyt Oxbow Books, Oxford, pp 169–179 M, Evershed RP (2013) Earliest evidence for cheese making in Pietrzak S, Langer JJ (2012) Badania archeometryczne substancji the sixth millennium BC in northern Europe. Nature 493:522–525 organicznej z krzemiennych grocików z cmentarzyska ludności Schrader B (2008) Infrared and Raman spectroscopy: methods and kultury mogiłowej w Górzycy nad Odrą. Folia Praehist Posnan applications. Wiley, Chichester 17:333–344 Shi M (1993) The discussion on the origin and distribution of pottery Poulain M, Baeten J, De Clercq W, De Vos D (2016) Dietary practices Zeng and Yan. Essays on Archaeological Culture 3. Cultural Rel- at the castle of Middelburg, Belgium: organic residue analysis of ics Press, Beijing 16th- to 17th-century ceramics. J Archaeol Sci 67:32–42. https:// Silverstein RM, Webster FX, Kiemle D, Bryce DL (2014) Spectromet- doi.org/10.1016/j.jas.2016.01.006 ric identification of organic compounds. Wiley, Chichester QPICRA (2006) Reports about changning site excavated in Qinghai Skibo JM (2013) Understanding pottery function: manuals in archaeo- Province China. Cult Herit News 2006:12–20 logical method, theory and technique. Springer, New York Rao H, Li B, Yang Y, Ma Q, Wang C (2015) Proteomic identification Stott AW, Berstan R, Evershed RP (2003) Direct dating of archaeo- of organic additives in the mortars of ancient Chinese wooden logical pottery by compound-specific C-14 analysis of preserved buildings. Anal Methods 7:143–149. https://doi.org/10.1039/ lipids. Anal Chem 75:5,037–5,045. https://doi.org/10.1021/Ac020 C4AY01766H 743y Rao H, Yang Y, Hu X, Yu J, Jiang H (2017) Identification of an Ancient Trąbska J, Wesełucha-Birczyńska A, Zięba-Palus J, Runge MT (2011) Birch Bark Quiver from a Tang Dynasty (AD 618-907) Tomb Black painted pottery, Kildehuse II, Odense County, Denmark. in Xinjiang, Northwest China. Econ Bot 71:32–44. https://doi. Spectrochim Acta A Mol Biomol Spectrosc 79:824–830. https:// org/10.1007/s12231-0179369-z doi.org/10.1016/j.saa.2010.08.068 Regert M (2004) Investigating the history of prehistoric glues by gas Wang Q (2015) The preliminary discussion of the difference of the chromatography-mass spectrometry. J Sep Sci 27:244–254. https livelihood models in river valley areas during Qijia Culture period ://doi.org/10.1002/jssc.200301608 in Qinghai Province. J Qinghai Normal Univ (Philos Soc Sci) Regert M (2007) Elucidating pottery function using a multi-step ana- 37:64–69 lytical methodology combining infrared spectroscopy, mass spec- Wei S, Pintus V, Pitthard V, Schreiner M, Song G (2011) Analytical trometry and chromatographic procedures. In: Barnard H, Eerkens characterization of lacquer objects excavated from a Chu tomb in JW (eds) Theory and practice of archaeological residue analysis. China. J Archaeol Sci 38:2,667–2,674 Archaeopress, Oxford, pp 61–76 Wen H (2006) The shift of the plant and animal in China in the histori- Regert M, Colinart S, Degrand L, Decavallas O (2001) Chemical cal period. Chongqing Publishing House, Chongqing alteration and use of beeswax through time: accelerated ageing Wen H, He Y (1979) China’s forest resources distribution in history. tests and analysis of archaeological samples from various envi- Natural Res 2:72–85 ronmental contexts. Archaeometry 43:549–569 Wiktorowicz CJ, Arnold B, Wiktorowicz JE, Murray ML, Kurosky Regert M, Garnier N, Decavallas O, Cren-Olive C, Rolando C (2003a) A (2017) Hemorrhagic fever virus, human blood, and tissues in Structural characterization of lipid constituents from natural Iron Age mortuary vessels. J Archaeol Sci 78:29–39. https://doi. substances preserved in archaeological environments. Meas Sci org/10.1016/j.jas.2016.11.009 Technol 14:1,620–1,630 Xie D (2002) Pre-history archaeology in Gansu-Qinghai area. Cultural Regert M, Rolando C (2002) Identification of archaeological adhe- Relics Press, Beijing sives using direct inlet electron ionization mass spectrometry. Yang J (2004) A comparison of the economic formation in the Eurasian Anal Chem 74:965–975 steppes with that in the Great Wall zone in China. Archaeology Regert M, Vacher S (2001) Des adhésifs organiques sur un site de La 11:84–90 Tène au Grand Aunay (Sarthe). Archéopages 4:20–29 Yin H (2009) The research of the birch bark culture in Chinese ancient Regert M, Vacher S, Moulherat C, Decavallas O (2003b) Adhesive northern minorities. Master thesis. Inner Mongolia Univer- production and pottery function during the Iron Age at the site of sity, Huhhot, China Grand Aunay (Sarthe, France). Archaeometry 45:101–120. https Yu X (2006) The birch-bark culture of northern minorities thorough ://doi.org/10.1111/1475-4754.00098 understanding of history, archaeology and ethnology. Manchu Reunanen M, Holmbom B, Edgren T (1993) Analysis of archaeological Stud 1:113–121 birch bark pitches. Holzforschung 47:175–177 Zhang J (2002) The preliminary discussion on bronze Yan in Shang and Rice PM (1987) Pottery analysis, a sourcebook. The University of Chi- Zhou Dynasty. Master thesis. Northwest University, Xi’an, China cago Press, Chicago

1 3