Crafting illusions: Human-made composite coating used to simulate amber beads in prehistoric Iberia

Journal of Archaeological Science 168 (2024) 106011 Available online 22 June 2024 0305-4403/© 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/). Crafting illusions: Human-made composite coating used to simulate amber beads in prehistoric Iberia Carlos P. Odriozola a , b , * , Jos´ e ´ Angel Garrido-Cordero a , b , Ana C. Sousa b , Jos´ e María MartínezBlanes c , d , Galo Romero-García a , Daniel S´ anchez-G´ omez b , Manel Edo i Benaigues e , Diego Romero-Vera a , María Dolores Sim´ on-Vallejo a , María Dolores Zambrana Vega f , Jos´ e Luis Molina Gonz´ alez f a Dpto. de Prehistoria y Arqueología, Universidad de Sevilla, Seville, Spain b UNIARQ, Centro de Arqueologia da Universidade de Lisboa, Lisbon, Portugal c Instituto de Ciencia de Materiales de Sevilla, Universidad de SevillaConsejo Superior de Investigaciones Científicas, Seville, Spain d Dpto. de Química Inorg´ anica, Universidad de Sevilla, Seville, Spain e CIPAG, Col⋅lectiu per a la Investigaci´ o de la Prehist` oria i l’Arqueologia del Garraf-Ordal, Begues, Spain f Dpto. de Pintura, Universidad de Sevilla, Seville, Spain ARTICLE INFO Keywords: Imitation amber beads Prehistoric craftsmanship Iberian communities Material imitation Social identity ATR-FTIR Micro-CT scanning ABSTRACT The discovery of a set of beads, comprising both Sicilian amber and resin-coated beads in the Middle Bronze Age burial site of Cova del Gegant (Sitges, Barcelona, Spain), has sparked inquiries into whether the coating was intended for imitation or counterfeiting of amber. We assert that human-made materials, such as bead coatings, are intentionally conceived, designed, and crafted to fulfill specific functions. Thus, for an object to effectively fulfill its intended purpose, it must meet particular performance criteria influenced by situational factors. This paper aims to construct an empirically grounded narrative elucidating the development and function of resin-coated bead technology. Our methodology includes a comprehensive quantitative analysis of the coating and beads, an exploration of the interplay between technical choices and situational factors, and an investigation into whether the simulation of sensory performance characteristics played a pivotal role in the concept and design of resin-coated beads. Additionally, we synthesize data to unveil broader patterns related to the crafting and utilization of resin-coated and amber beads across time and space. We have documented resin-coated beads in the Iberian Peninsula from the Neolithic period (5th to 3rd millennia BCE) until at least the Middle Bronze Age (first half of the 2nd millennium BCE), where they coexisted with amber beads. Analysis employing ATR-FTIR and μ -CT imaging has revealed a composite coating comprising pine resin, beeswax, and carotene, adhered to shell beads with bone glue. This composite material represents the earliest known development in human history, unique to the Iberian Peninsula and without parallel in Prehistoric Europe. Our examination of the performance characteristics and functional roles of resin-coated beads suggests their potential as substitutes for amber beads, particularly in regions where amber was scarce or inaccessible. Despite being crafted from commonplace materials, these coated beads exhibit intentional design choices likely aimed at simulating the visual performance characteristics of amber. This deliberate effort, alongside their widespread distribution across time and space, indicates that composite-coated beads held symbolic and social significance akin to amber beads. 1. Introduction The discovery of a set, comprising two Sicilian amber beads and four pine resin-coated beads of comparable size and shape in the Cova del Gegant (Sitges, Barcelona, Spain) dating back to the 15th century BCE, has prompted questions into whether the coating technology employed * Corresponding author. Dpto. de Prehistoria y Arqueología, Universidad de Sevilla, Seville, Spain. E-mail address: [email protected] (C.P. Odriozola). Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: www.elsevier.com/locate/jas https://doi.org/10.1016/j.jas.2024.106011 Received 31 October 2023; Received in revised form 13 May 2024; Accepted 3 June 2024 Journal of Archaeological Science 168 (2024) 106011 2 was aimed for imitating 1 or counterfeiting 2 amber (Odriozola et al., 2019a). The same question arose when beads carved on non-fossil dark-red resin were found on king Tutankhamen’s and king Tetis’ tombs (Harding and Hughes-Brock, 1974; Kuhn et al., 2022; Lucas, 1948, p. 444). In both cases non-amber beads exhibited features similar to those valued in amber. There is speculation regarding the potential deception of Tutankhamen, Teti, and the buried individual at Cova del Gegant, a conjecture grounded in the historical practice of counterfeiting (Karampelas et al., 2020; King, 2014, 2022), and in the lesser value and negative connotations that modern society gives to imitations (Choyke, 2008, p. 5; Coneller, 2013; Nicholson and Shaw, 2000, p. 195; van Wijngaarden, 2008, p. 128). Amber beads and those resembling amber, crafted from natural materials, not only share formal characteristics but also likely undertake similar functional roles. This challenges the classification of these materials as mere imitations. For example, Amerindians made no distinction between gold and pyrite, considering both imbued with sacred light and functionally identical (Coneller, 2013, p. 121). Similarly, the ancient Egyptians from the Old Kingdom and Iberian communities from the Late Prehistory might not have distinguished between natural materials that shared physical features with amber. This shared functional role might transcend any perceived differences, reflecting the value they placed on these materials. Translucent natural materials, like amber, non-fossil resins, and certain translucent stones, not only share formal attributes but are also highly regarded for their rarity. Their scarcity and distant origins mandate extensive search and exchange networks for acquisition. As a result, this process significantly influences their social and functional significance. A striking example illustrating the interplay of scarcity and social valuation is exemplified by the cargo retrieved from the 14th-century BCE Uluburun shipwreck off the coast of Southern Turkey. Among the recovered artefacts were 41 beads fashioned from Baltic amber, alongside numerous other high-end items indicative of an elite collection. This find, analyzed by Bachhuber (2006, pp. 346–347), serves as compelling evidence of the esteemed status accorded to amber as a prized objects within ancient trade networks during that time. Notably, Pharaoh Thutmose III underscored this importance by specifically ordering a shipment of amber from Mycenaean Greece (Singer, 2016, pp. 257–258). Murillo Barroso and Montero Ruiz (2017) suggested that during the Late Prehistory in Iberia, amber possessed considerable social and economic value, attributed not only to its physical attributes but primarily to its rarity, scarcity, and distant origin. Similarly, rarity has been emphasized as a defining characteristic that grants materials, such as metals, significant economic influence (Hayden, 1995, p. 259). The archaeological evidence from Iberian Late Prehistory highlights a scarcity of amber artefacts, including beads, pendants, and components like dagger knobs and hairpins, often classified as elite display pieces. A total of 758 items across 84 sites from the 5th to the 2nd millennia BCE further underscores this scarcity, with over 75% concentrated in three specific sites: Anta Grande do Zambujeiro (168), the tholos of Montelirio (254), and Cova dels Muricecs de Cellers (135) (Murillo-Barroso et al., 2018; Odriozola et al., 2019b). Despite the low frequency, the significance of amber for elites is evident, as 75% of cataloged items are found in three tombs associated with high-end items such as gold, cinnabar, or ivory within others. Distinguishing between natural materials, derived from elements found in nature such as amber, and human-made materials, which are crafted by humans and not naturally occurring is imperative. Humanmade materials not only stem from deliberate actions but also demand meticulous intentionality in their creation, taking into account the limitations imposed by skill and knowledge (Franssen, 2009, p. 21). We propose that human-made materials, such as beads coatings, are consciously conceptualized, designed, and crafted to effectively serve particular purposes, whether utilitarian, social, or ideological (Feng and Feenberg, 2009, p. 105; Kingery, 2001, p. 125). Therefore, for an object to adequately fulfill its aimed functions, it must satisfy specific performance characteristics (as outlined by Schiffer and Skibo, 1997, p. 31), which are shaped by the aimed technological, social, and ideological functions, as well as by the physical, social, and cultural environment (Kingery, 2001, p. 125, 1996a, p. 181; Skibo and Schiffer, 2008, p. 110). Thus, the design process necessitates the integration of technical and cultural considerations to create tangible artefacts tailored to specific contexts (Feng and Feenberg, 2009, p. 105). In essence, technology is shaped by its context, with its form and prevalence contingent upon local historically constituted conditions and characteristics (Skibo and Schiffer, 2008, p. 67). Building upon these contingencies, in this paper we aspire to build an empirically grounded narrative that explains the development and function of this bead-coating technology. Initially, we conduct a comprehensive quantitative study to scrutinize the nature and structure of the coating and the beads. Subsequently, we investigate the interplay between technical choices and situational factors. Thirdly, we explore whether the simulation of sensory performance characteristics such as color, odor, and density by craftsmen played a central role in the concept and design of resin-coated beads. Finally, we synthesize data to elucidate broader diachronic and spatial patterns related to the production and use of resin-coated and amber beads. 2. Materials and method A thorough examination of our extensive records partially accessible at https://pepadb.us.es (Romero-García et al., 2024), combined with available data, has facilitated the identification of potentially coated beads after the first case study were detected. Subsequently, these beads were verified in museums. We have documented the presence of coating on more than 2000 beads across 15 different archaeological sites (Fig. 1) from 5th to 2nd millennium BCE. These coated beads are predominantly concentrated in the vicinity of the Tagus estuary, as depicted in Fig. 1. Following a visual inspection (illustrated in Fig. 2 and detailed in Table 1), we proceeded to analyze a sample of 50 coated beads for further study. 1 Imitations typically involve the use of materials of lesser value, possessing comparable sensory attributes such as color, luster, or clarity, in order to replicate the features of the targeted material (Karampelas et al., 2020). Additionally, Karampelas et al. (2020, p. 67) make a distinction between imitations (derived from natural materials), simulants (manufactured products), and synthetics, which are created through modern techniques of crystal growth. Therefore, imitation involves replicating some or all features of an object, often leveraging technology, to produce a similar commodity. This imitated object is crafted to be accepted and valued akin to the original but typically involves a lower economic investment.However, the term "imitation" has faced criticism for its narrow focus on the social impact of imitations, neglecting the underlying social and cognitive imperatives behind imitation, as well as the negative connotations associated with perceived value as a more affordable alternative sought after by individuals with limited access to wealth (Choyke, 2008, p. 5; Nicholson and Shaw, 2000, p. 195). It is crucial to note that imitations hold their own value and meaning, and until very recently, were not considered to be of lesser economic or social value (Coneller, 2013; van Wijngaarden, 2008, p. 128).Skeuomorphs, defined as objects or symbols replicated in a different raw material from the expected one, according to Frieman (2013), do not seem to align with the issue presented here, in our opinion. In a classic interpretation by Vickers, skeuomorphism "was a conscious strategy designed to give less valuable materials a higher economic worth" (Frieman, 2013, p. 320). However, skeuomorphism tends to connect ideas and symbols more than the material itself, given the clear distinction and perception between the original materiality and the skeuomorph: "the skeuomorph is trying to be something that it isn’t" (Knappett, 2002, p. 111). 2 Counterfeiting involves the deliberate intention to deceive or defraud by creating an exact imitation of a valuable item. C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 3 The reconstruction of the technical system used in crafting these coated beads involved a three-step process: Step 1: Visual Examination and Microscopy •Initial examination included a close-up visual inspection and in-situ digital microscopy. •Cross-polarization mode was employed to enable magnification up to x160. •An AM7915MZTL Dino-Lite Edge Digital USB Microscope was utilized for this purpose. Step 2: Microsampling and ATR-FTIR Analysis •Microsamples were collected from the coating layer of the beads using a scalpel. •Fig. 3c illustrates the presence of a white substance adhering to the resin sample. •Due to the small size of the beads and microsamples, it was not feasible to remove the white substance before conducting ATR-FTIR analysis. •A Nicolet iS5 FTIR spectrometer equipped with an iD7 ATR device was used to analyze the microsamples. •Infrared absorption spectra were collected by scanning each specimen 64 times within the range of 4000–525 cm −1 , with a resolution of 4 cm ⁻1 . •The spectra exhibited broad bands with slope changes and shoulders, indicative of multiple overlapping bands (the raw data, along with the code to plot each spectrum, is available in Supplementary 2 - dx. doi.org/10.6084/m9.figshare.25809352). •To identify the number of overlapping bands and fit band parameters (O’Haver and Green, 1976), the second gap derivative (Stevens and Ramirez–Lopez, 2014) of the spectra was employed (see Supplementary 2 for details and code on band fitting parameters - dx. doi.org/10.6084/m9.figshare.25809352). •Band positions were identified after normalization and offset correction, using a custom-built minimum/maximum identification function (see Supplementary 2 for full data processing details including code - dx.doi.org/10.6084/m9.figshare.25809352). Step 3: Micro-Computed X-ray Tomography ( μ -CT) Scanning •Selected samples underwent μ -CT scanning to generate threedimensional models of the bead cores and coating layering (raw data available on dx.doi.org/10.6084/m9.figshare.25730319; dx. doi.org/10.6084/m9.figshare.25730511; dx.doi.org/10.6084/m9. figshare.25730553; dx.doi.org/10.6084/m9.figshare.25730604; dx. doi.org/10.6084/m9.figshare.25730616; dx.doi.org/10.6084/m9. figshare.25730634; and dx.doi.org/10.6084/m9.figshare.25730 655). •During μ -CT scanning, a 3D digital model was generated for each bead, facilitating the creation of multiple cross sections for analysis. •Pixel intensity on cross-section images corresponded to the attenuation of transmitted x-rays (Hermanek et al., 2018). •Beads underwent μ -CT scanning with the Zeiss Xradia Versa 610 Xray microscope CT scanner. •Image processing, including brightness/contrast correction, contrast enhancement, differentiation of adjacent structures, and obtaining orthogonal views and resizing, was conducted using Fiji software (Schindelin et al., 2012). 3. Results Close examination of the beads (Fig. 4) reveals a resinous coating layer and the radial ribs, ridges, and grooves of a molluscan valve of the family Cardiidae, most likely Cerastoderma edule, serving as the bead’s Fig. 1. Location of the studied beads. 1. Alto da Feteira, 2. Buraca da Moura da Rexaldia (Gruta da Rexaldia), 3. Corominas 1, 4. Costamar, 5. Cova da Moura, 6. Cova de Can Figueres, 7. Cova del Gegant, 8. Gruta do Furadouro de Rocha Forte, 9. Quinta do Anjo 1 - Grutas do Casal do Pardo 1, 10. Quinta do Anjo 3 - Casal do Pardo 3, 11. La Molina CE17, 12. La Pijotilla T3, 13. Praia da Samarra, 14. S˜ ao Paulo 2, 15. Zambujal. C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 4 Fig. 2. Coated resin beads recorded and analyzed in this work. Table 1 Inventory of 4th-to-2nd millennia BCE sites with coated beads recorded in this work. LN: Late Neolithic; C: Copper Age; EBA: Early Bronze Age. D: Dolmen; NC: Natural cave; AC: Artifitial cave; P: Pit; FS: Fortified settlement. MMTN: Museu Municipal de Torres Novas; MTV: Museu de Torres Vedras; MNA: Museu Nacional de Arqueologia (Lisbon); Mgeo: Museu Geologico (Lisbon); MMA: Museu Municipal de Almada; Museo Municipal de Estepona; CIPAG: Col⋅lectiu per a la Investigaci´ o de la Prehist` oria i l’Arqueologia del Garraf-Ordal (Begues); MAPS: Museo Arqueol´ ogico Provincial de Sevilla; SERP: Seminari d’Estudis I Recerques Prehist` oriques, University of Barcelona; MAA: Museo Arqueol´ ogico de Almería; CRIV: CRIVARQUE, MBC: Museu de Bellas Artes de Castell´ on, DPAUS: Departamento de Prehistoria y Arqueología de la Universidad de Sevilla. Site Chrono. Type # #anal. #FTIR-ATR μ -CT Museum 1 Alto da Feteira LN/C D 22 1 TRUE TRUE MGeo 2 Buraca da Moura de Rexaldia LN/C NC >1000 10 TRUE TRUE MMTN 3 Corominas 1 LN/C AC 406 5 TRUE TRUE MME 4 Costamar T-31002 MN-LN? P 869 10 TRUE TRUE MBAC 5 Cova da Moura LN/C NC >1 0 FALSE TRUE MTV 6 Cova de Can Figueres LN/C NC >1 1 FALSE TRUE CIPAG 7 Cova del Gegant EBA NC 4 4 TRUE FALSE SERP 8 Furadouro da Rocha Forte LN/C NC 13 2 TRUE TRUE MNA 9 Gruta da Marmota LN/C NC >100 0 FALSE TRUE CRIV 10 La Molina CE-17 LN/C AC 2 2 TRUE FALSE MAPS 11 La Pijotilla T-3 C AC >50 1 TRUE FALSE DPAUS 12 Praia da Samarra LN/C AC 39 2 TRUE TRUE MGeo 13 Quinta do Anjo 3/Casal do Pardo LN/C AC 11 2 TRUE TRUE MNA 14 S˜ ao Paulo 2 LN/C AC >350 6 TRUE TRUE MMA 15 Zambujal LN/C FS 1 0 FALSE TRUE MTV C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 5 core. Notably, La Molina and Corominas 1 are exceptions. The ATR-FTIR analysis yielded a wealth of information about the coating’s composition, identifying components from both the bead shell core and the coating (see Supplementary 2 for a detailed spectral analysis - dx.doi.org/10.6084/m9.figshare.25809352). The CO 3 2− vibrational modes ν 1 , ν 2 , ν 3b , ν 4a , and ν 4b (Fig. 5a) were linked to the shell core (aragonite), and the (PO 4 ) vibrational modes ν 1 , ν 3 and ν 4 to hydroxyapatite (bone hard tissue). Fig. 5a displays bands associated with hydroxyapatite’s (PO 4 ) vibrational modes, namely, ν 1 , ν 3 and ν 4 . These modes have been linked to hydroxyapatite precipitation in previous studies (Odriozola et al., 2019a). Given that bone is water-soluble, this precipitation could take Fig. 3. Close-up images (x39.1 and ×144 augmentation) of a micro sample taken from S˜ ao Paulo 2 MMA 7692 bead showing the white attached material coming from the bead core. The yellow framed image in A shows the section leaved after sampling. B. Exterior side of the sample. C. Interior side of the sample. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.) Fig. 4. Images showing the resinous coating layer and the beads shell core radial ribs (yellow arrows). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.) C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 6 place under specific pH conditions. However, upon microscopic examination, no evidence of hydroxyapatite precipitation was observed on the resinous layer. The existence of bone in this context might be attributed to the application of a primer bone layer. If this hypothesis holds true, it implies that the bone underwent some form of processing to enable the bone collagen to serve as an adhesive. Furthermore, the detection of the customary bone protein vibrations, such as amide I (C – – O stretching), amide II (N–H stretching), and amide III (C–O stretching) in the spectra, strongly indicates the utilization of bone glue in this context. The presence of C–C skeletal vibrations of abietic/dehydroabietic acid in the spectra suggests the use of a natural terpenic resin to coat the bead. However, natural resins undergo rapid oxidation and polymerization processes. Consequently, in the spectra, bands associated with not only abietic/dehydroabietic acid but also compounds derived from its aging were detected. These compounds include abietic, dehydroabietic, 7-oxodehydroabietic, 15-hydroxy-7-oxo-dehydroabietic, and isoprimaric acids. This strongly indicates the use of a tree resin from the Pinus genus (Fig. 5a, Supplementary 2 - dx.doi.org/10.6084/m9. figshare.25809352). Furthermore, Figs. 5a and 5b reveal the presence of vibrational stretching, deformation, and torsion of C–H bonds in the long carbon chains of waxes, as well as the C – – O stretching characteristic of carboxylic acids. This enables the identification of beeswax in the samples (Casanova et al., 2016). In addition, several bands associated with calcium oxalate biomineralization have been detected. This biomineralization could be a result of fungal or lichen biodegradation, or the oxidative breakdown of natural resins and waxes (Bordignon et al., 2008). Hence, the presence of these compounds could be linked to the preservation of the beads. Lastly, in Figs. 5a and 5b, there are indications of C(O)–O and –OH vibrations in amide III, C–O vibrations in amide II, –C – – H vibrations in amide I, as well as hydroxyl (-OH) and –CH groups of carotenoids. Carotenoids are tetraterpene pigments found in various organisms, including photosynthetic bacteria, certain archaea, fungi, algae, plants, and animals (Maoka, 2020). The presence of carotenoids in the coating may suggest the use of an organic dye, such as linseed oil. Among potential sources of carotene, two prominent options in European forgery recipes are saffron and linseed oil (King, 2014, 2022). While the cultivation of saffron is traceable only to the first millennium BCE, there is robust historical evidence supporting the use of linseed oil as a primary source of carotenoids. The cultivation of flax, from which linseed oil is derived, dates back to roughly 8000 BCE in the Near East, with evidence of its exploitation in wild form dating back to approximately 12000 BCE (Fu et al., 2012). Moreover, linseed cultivation for oil is well-documented in the Iberian Peninsula, with its cultivation dating to around 6000 BCE (Pe˜ na-Chocarro et al., 2018). This historical context endorses the feasibility of linseed oil as a viable source of carotenoids in this composite coating. Fig. 6 displays orthogonal cross-sections of a bead from Quinta do Anjo 3/Casal do Pardo 3. Fig. 7, magnified by a factor of 20, provides a closer look at the same bead. These images reveal several key observations: 1. The beads exhibit a layered structure consisting of a non-uniform thin layer, typically around 17–20 μ m, which is likely calcite formed during the beads’ burial (though not observed in all scanned beads). In addition, there are two layers covering the core of the bead. This set comprises a bone glue layer, which is 50–70 μ m thick, Fig. 5a. ATR-FTIR spectra of the coating in the diagnostic region (525-1800 cm −1 ). A. Second derivative of the spectra. B. Offset corrected and normalized FTIR-ATR spectra. Top border of A show band positions after 2nd derivative analysis (see Supplementary 2 for a detailed spectral analysis and the accompanying code for this figure - dx.doi.org/10.6084/m9.figshare.25809352). Color shaded boxes in A shows the area in which the identified compounds are peaking. C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 7 and a resin layer on top, which is 220–240 μ m thick, as depicted in Fig. 7. 2. The outer surface of the resin layer, approximately 60–80 μ m, has begun to develop fine cracks (as seen in Figs. 4 and 6). This cracking is a consequence of the typical oxidation and polymerization process associated with terpenoids, although the layer has not yet begun to peel. 3. The base layer serves to smoothen the bead’s surface and conceals any irregularities in the shell. When glue is applied, it seeps into the surface pores of the shell, creating a mechanical bond as it hardens (Claisse, 2016). This suggests that the resin, or possibly a composite of resin and beeswax, was applied prior to the hardening of the bone glue. Fig. 5b. ATR-FTIR spectra of the coating in the diagnostic region (2200-4000 cm −1 ). A. Second derivative of the spectra. B. Offset corrected and normalized FTIRATR spectra. Top border of A show band positions after 2nd derivative analysis (see Supplementary 2 for a detailed spectral analysis and the accompanying code for this figure - dx.doi.org/10.6084/m9.figshare.25809352). Color shaded boxes in A shows the area in which the identified compounds are peaking. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.) Fig. 6. Orthogonal views of the micro CT scan of Casal do Pardo 3 bead. A. Micro Ct scan slice 505; B.YZ view; C. XZ view. (60 kV, 110A; 2.5s; Optical Magnification: 0.391150; pixel: 5.467986). C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 8 4. Discussion While the genesis of the bead-coating technology may have initially arisen from a serendipitous discovery intertwined with various activities, innovations, scientific breakthroughs, or technological advancements, there are strong indications suggesting deliberate intentionality in the design and creation of these beads. Human behavior, including design endeavors, is inherently purposeful and guided by intentions (goals) and actions (Ajzen, 1985, p. 11; Franssen, 2009, p. 21). Thus, we posit that the underlying goal propelling the development and craftsmanship of this bead-coating technology likely aims to emulate the physical characteristics of amber. This aim encompasses a comprehensive effort to replicate amber’s formal properties, particularly its sensory performance attributes related to sight, touch, or smell, which play significant roles in both design considerations and practical applications (Skibo and Schiffer, 2008, p. 13). The simulation (as per Karampelas et al., 2020, p. 67) of socially valued objects like amber beads using human-made materials may be driven by several factors. These factors not only define the ideal performance characteristics an object should possess for a specific purpose (Schiffer and Skibo, 1997, p. 34) but also significantly influence the design and manufacturing stages of the object, as emphasized by Kingery (1996b, p. 176). Among the numerous factors that can be considered as situational factors motivating the design and craftmanship of amber-like beads the primary one might be the profound changes in social relationships occurred during Iberian Late Prehistory. Between the 6th and 2nd millennia BCE, the Iberian Peninsula underwent significant socio-economic and political transformations, primarily driven by the adoption of the neolithic lifestyle. This pivotal shift led to escalating social inequality and the establishment of hierarchical structures, reaching its apex in the 2nd millennium BCE with the formation of highly stratified societies and intricate socio-political frameworks (Garcia Sanju´ an, 2006). Certainly, the rise of elites and the ensuing social stratification likely prompted the demand for items that could visually reinforce social distinctions and signal the status of individuals. Analogous to the manner in which early 20th century Melanesian high-ranking kula chiefs utilized personal adornments to denote their elevated status (Earle, 1987), influential figures within Iberian Late Prehistoric communities may have utilized personal adornments as overt symbols of social differentiation during interactions with other leaders or members of society. We propose that amber artefacts served as elites-framing objects, as they are inherently unique creations crafted from a rare material with origins in distant places, requiring expert craftsmanship for their production or long exchange chains. Consequently, these objects are not merely commonplace possessions; they embody exclusivity, symbolizing power and wealth. Therefore, amber items can be seen as emblematic (as per Lull, 2007, pp. 230–232), and inalienable (as per Earle, 2004, pp. 156–157), further emphasizing their significance and value as pointed out by Murillo Barroso and Montero Ruiz for the Iberian Peninsula (2017, pp. 280–281). When supply chains fall short of meeting the escalating demand for rare material-crafted beads among elites, spurred by widening social inequalities, a convergence of technological and social forces frequently catalyzes the emergence of new artifact categories. These novel objects must effectively replace their predecessor’s techno-, socio-, and ideofunctions. Therefore, the development of this bead-coating technology could be linked to societal demand for display items, particularly among elites who encountered obstacles in accessing amber for various reasons. This demand extended beyond fulfilling practical needs such as selfpresentation, or bodily ornamentation. Instead, we argue that the demand primarily arose from economic competition, a concept akin to what Hayden (1995) proposed for so-called prestige technologies. Similar to the adoption of turquoise ‘imitations’ in the Near East, where a noticeable surge in demand for rare colored stones like turquoise and lapis lazuli emerged due to the complexity of socio-political structures. This surge prompted the production of synthetic gemstones (Moorey, 1999, p. 182). Initially, artisans crafted these ‘imitations’ by firing fossil mastodon tusks, known as odontolite (Bursali et al., 2017a, 2017b, p. 17; Reiche et al., 2001; Taniguchi et al., 2002). Over time, these imitations evolved, incorporating materials such as glazed dull stones or faïence, with glass eventually emerging as the predominant material in their production processes (Moorey, 1999, p. 182). We posit that the primary impetus behind the development of beadcoating technology was the desire to convey social distinctions through their display in various social settings. These beads likely held associations with high prestige and were perceived as valuable. Consequently, the design of amber-like beads may have stemmed from societal demand for objects that symbolized status. This technological advancement facilitated meeting the increasing demand for valuable items that could not be solely satisfied through the amber exchange. For instance, the earliest recorded use of resin-coated beads at Costamar in the early to mid-5th millennium BCE aligns with the initial evidence of differential use of amber beads in specific burial contexts along the Atlantic coast of the Iberian Peninsula, particularly in the northwest and southwest regions (see Odriozola et al., 2019b). This correlation suggests a significant engagement between these two phenomena. Furthermore, from the mid-4th to the mid-3rd millennium BCE, the use of amber as a status marker persisted and increased, while resin-coated beads emerged in regions where amber might be scarce, such as the Tagus estuary or the coast of M´ alaga (Fig. 8). This observation underscores the possibility that resin-coated beads may have served as a practical solution during periods of limited amber availability, given their association with high-value objects (Table 2), thereby assuming a functional role as objects of heightened social significance. Moreover, the perception of coated beads as exclusive items used to signify power and wealth receives additional support from the notion that personal adornment serves as a means to manifest new social roles Fig. 7. Micro CT scan image of Casal do Pardo 3 (60 kV; 108A; 12s; Optical Magnification: 3.973200, Pixel: 0.538379). C.P. Odriozola et al. Journal of Archaeological Science 168 (2024) 106011 9 and distinctions, as Costamar tomb 31002 exemplifies (see Supplementary 1 - dx.doi.org/10.6084/m9.figshare.25809679 - for detailed archaeological contexts). Additionally, the contexts in which both amber and coated beads are displayed exhibit similar levels of opulence and monumentality. Therefore, it is plausible that both types of beads held comparable social value and, consequently, played analogous roles in social interactions. If this bead-coating technology were to be specifically designed to fulfill amber’s technological, social, and ideological functions, as suggested, the bead design would need to consider the formal attributes of amber. Throughout history, written sources describing amber, whether focusing on its authenticity, origin, or methods of counterfeiting, have consistently emphasized color and clarity as among the most significant formal attributes (King, 2014, 2022). Moreover, these written sources unanimously highlight the predominant role of visual perception among the various sensory attributes, while other sensory aspects such as odor or density, though important, often recede into the background. Consequently, we argue that color and clarity were most likely primary considerations in the design of these coated beads, alongside practical concerns such as durability (the ability of the coating to withstand being bonded to the core for extended periods of time). Craftsmen when designing an object often face several technical options when addressing specific issues. Each choice, however, may introduce new challenges due to its impact on subsequent technical decisions. As each issue is resolved, adjustments to prior technical decisions may become necessary. Consequently, one can anticipate that technical choices typically influence an artifact’s formal properties during downstream activities (Schiffer and Skibo, 1997, p. 31). The process of applying coatings typically involves the initial application in a liquid state, followed by drying to achieve the final solid form. During the drying of pine resin, it undergoes a reduction in Fig. 8. Spacetime use patterns of resin-coated beads compared to that of amber. Location of the studied beads. 1. Alto da Feteira, 2. Buraca da Moura da Rexaldia (Gruta da Rexaldia), 3. Corominas 1, 4. Costamar, 5. Cova da Moura, 6. Cova de Can Figueres, 7. Cova del Gegant, 8. Gruta do Furadouro de Rocha Forte, 9. Quinta do Anjo 1 - Grutas do Casal do Pardo 1, 10. Quinta do Anjo 3 – Gruta 3 do Casal do Pardo, 11. La Molina CE17, 12. La Pijotilla T3, 13. Praia da Samarra, 14. S˜ ao Paulo 2, 15. Zambujal (data available at https://pepadbase.us.es/). C.P. Odriozola et al.