Amber in the Circum-Adriatic Bronze Age

1.2.1. Exchange, trade and other forms of amber circulation

Two words: ‘exchange’ and ‘trade’ have been in the centre of amber routes debate; therefore, how we define these rather capacious terms influences our image of the entire subject (cf. Cwaliński 2017). Exchange is recognisable as ‘interactional process that is common in most biotic and abiotic systems’ (Oka/Kusimba 2008, 340; cf. Befu 1977). In the social dimension it takes a form of an act of giving and receiving something in return, while maintaining reciprocal benefit derived from some mutual (even if vague) comprehension of ‘balance or equivalence between what is given and what is received’.⁵ However, understanding of this kind of interaction is so broad that it covers transfer of material as well as non-material goods, here mainly transmission of information.⁶ Hence, material manifestation of a gift in the form of an object changing its owner is not required for the occurrence of exchange.

Foregoing definition is largely based on anthropological viewpoint which perceives exchange as socially embedded process. Notion of exchange as a ‘total social fact’ (Mauss 2001, 167) has its roots in ground-breaking analyses of non-Western economies published in the 1920s (Mauss 1990; Malinowski 1992), which were later adopted by primitivist economic historians (Oka/Kusimba 2008, 343). Key in this regard is the idea that the gifts are exchanged to strengthen social relationship between people (Mauss 1990, 3). Despite the fact that the later discussion among the primitivists almost erased concepts of profit or commerce from prehistoric and non-Western societies, treating them as not sufficiently developed, largely agriculture-dependent,⁷ the seminal works of Mauss and Malinowski laid solid foundations for modern meaning of exchange. Consequently, we can argue that a transferred object, notwithstanding its imposed market or symbolic value, is less important in comparison to the non-economic gains, e.g. gratitude or satisfaction that cannot be measured by means of commercial profit or loss. One should not forget that exchange may be a way to obtain even bigger gains, often strictly non-commercial, examples of which point to transmission of technological knowledge or long-lasting effects such as alliances and marriages.⁸

Another significant assumption connected with anthropological viewpoint on exchange is that in traditional societies this was never purely economic transaction, for it bore great significance in rituals.⁹ Behavioural symbolism of exchange seen as, e.g. gesture can have much greater impact when it is performed in a pronounced way (Renfrew/Bahn 2007, 337). Moreover, intentions of the main actors of the process, attitudes of its spectators and circumstances in which it takes place can alter perception of the whole act of exchange and render its significance.

The above given description is limited only to the act of giving motivation by positive premises aimed at achieving reciprocal, although not necessarily equal, benefits by the agents. However, one should bear in mind that various forms of reciprocity, that is often considered obligatory in the act of giving (Oka/Kusimba 2008, 343), may be encountered, ranging from balanced benefit to one (delayed reciprocity) or both-sided unrequited gift (conflict of interests) (cf. Sahlins 1972, 191–196).

If exchange can also involve material goods, how then one should understand the meaning of trade? Following to some extent, definition of R. Oka and Ch. M. Kusimba trade is regarded as ‘the material-economic component of exchange’; however in opposition to quoted authors, I do not consider it as a ‘necessary part of any social exchange’ (Oka/Kusimba 2008, 340). It is a certain way of realisation of a basic concept of exchange; however, in this process material value of exchanged goods matters more to the participants than non-economic gains (Doğan 2008, 36; Doğan/Michailidou 2008, 20). Trade does not exclude the presence of factors constitutive to exchange which are related to renegotiation of social relationships by achieving other benefits than simple material enrichment; however, their importance decreases in relation to economic profit (Palavestra/Krstić 2006, 66). Presented approach may be seen as a response to suggestion of K. L. Hutterer, who argued that archaeologists hitherto overstated social side of exchange at the expense of the economic one (Hutterer 1977, 8; after Oka/Kusimba 2008, 340). In reality trade is intrinsic in both social and economic aspect of exchange, which are ever-present in commodity transactions between humans (cf. Oka/Kusimba 2008, 367–368). One can visualise this notion in the example of everyday shopping, when regular buyers are polite or even friendly towards the sellers in exchange for their fast and efficient service, even though their main purpose is simply to buy chosen products. In the world of big markets and economies, merchants aim at conducting their businesses in amicable atmosphere, build by gestures and courtesies, which can help to establish mutual trust (cf. Paterson 1998, 148–149; Morley 2007, 86).

In summary I consider exchange as a more general process, much broader in its possible forms, than trade which is more concrete and conditioned realisation of this basic interaction. We saw the particularity of trade in the way it is narrowed to exchange motivated by certain (rather high) value of some commodity in relation to the price or costs of its purchase. Nevertheless, as we are discussing trade in the broad geographical context concerning the common phenomenon of circulation of a certain material – amber, it is inescapable to regard trade as an organised process. Hence, one has to name at least basic conditions required for the occurrence of large-scale, long-distance trade.

C. Renfrew, who represents minimalistic approach to trade, underlines the factor of distance and importance of reciprocity (Renfrew 1969, 152); however, essence of trade is contained in procurement of materials, by whatever mechanism (Renfrew 1977, 72). It may seem that A. Harding takes the opposite position, as he stresses that trade implies use of markets and money, thus making this term rather inappropriate in relation to prehistory (Harding 2013b, 370). However, it is worth underlining in this place that we are speaking of various levels of economic development, i.e. proto-bureaucratic (institutionalised) mechanisms of trade and exchange in early civilisations of the Near East can hardly be transposed on the Bronze Age realities in most of Europe (cf. Sherratt/Sherratt 1991; Tyborowski 2009).

Big markets, professional traders and other manifestations of economic sophistication have often been exclusively attributed to high commerce which was meant to represent periods of prosperity in the Mediterranean during the antiquity. Lack of large-bulk trade conducted in highly organised infrastructure was regarded as a setback to more primitive economy capable only of small-scale exchange. However, it is argued that ‘significant volumes and densities of exchange can exist without such infrastructure’ (Horden/Purcell 2000, 144–145). Money, on the other hand, as a fixed token of trade appeared much later than long-distance transfer of goods and therefore should be not viewed as sine qua non condition of trade’s existence, as barter, for instance, is known from pre-monetary societies, and more traditionalistic communities rely on it even in modern times (Doğan 2008, 36; Doğan/Michailidou 2008, 20).

Contrary opinion to the minimalistic approach to trade is reflected in the definitions invented by K. Polanyi, who perceived trade from institutional perspective. His position is represented by the statements that ‘trade is a method of acquiring goods that are not available on the spot’ which are moved ‘through the market, that is, an institution embodying a supply-demand-price mechanism’ (Polanyi 1975, 133–134). Although this definition alone sets an interesting conditioning of trade, the general viewpoint of Polanyi, later adopted by substantivists, opted for centrally administered and controlled process of acquisition, redistribution, production and consumption as a domain of political elites (cf. Polanyi et al. 1957; see also Oka/Kusimba 2008, 344). Accordingly, decision-making is entirely socially dependent, operation of the market is fixed and elites have exclusive mandate on exchange of luxury products (cf. Halperin 1984).

It would be a painstaking task to describe in detail the debate between primitivists/substantivists and modernists/formalists.¹⁰ To close this overview of the meaning of trade, I will limit myself to saying that in the following study a more conciliatory approach is adopted: socio-political complexity is not seen as a precondition for emergence of trade, and the latter is not considered as strictly commercial relationship, nor is it just a non-economic process (cf. Adams 1992).

Apart from the premises for undertaking trade, its infrastructure and relation to the political institutions is the most important to define the actors of exchange. Here they are given a major role as self-motivated agents, capable of independent actions, driven by the knowledge of exchange network and ability to assess rates of gain/loss. Trade could be handled both by individuals (Sherratt/Sherratt 1991, 365; Bryce 2002, 99) or larger entities, such as merchant guilds, e.g. karum (Kuhrt 1998, 22; Tyborowski 2009, 138), or political elites, e.g. Minoan and Mycenaean palaces.¹¹ In order to engage in trade, it was required of agents to possess sufficient bargaining power and commodities either their own or entrusted to them (Oka/Kusimba 2008, 364). If we accept the ‘structuralist’ approach to exchange as ‘a way to mediate conflict and maintain social structure’ (see e.g. Hodder 1980; Earle 1997), or in other words as a subject to structural process between its social, political and ritual components, then the main participants may be endowed with Giddensian agency, that would allow them to operate within the structure and occasionally alter it (see Giddens 1979, 1984).

In conclusion to above consideration, it is possible to propose three crucial preconditions for the emergence of trade. First one is similarly perceived system of values, either commercial or symbolic, typical to particular resources or products, which forms a common ground for negotiations.¹² Second precondition is the existence of ideas of demand and supply among the communities, which would induct goods into motion and launch process of trade.¹³ Finally, there should be an agent – a middleman, who would be responsible for delivery of goods and will have the power and authority to conduct transactions.¹⁴

Although exchange and trade most probably were the main ways of obtaining amber, one should not forget that there are other means by which this material could circulate over considerable distances. Amber findspots in the circum-Adriatic zone do not necessarily represent final stages of exchange (e.g. as a gift) or trade (i.e. when objects change hands from supplier to consumer). More distant amber deposits within hoards or single pendants inside warrior graves may have a history of war trophies (Palavestra/Krstić 2006, 65), captured during raids on more prosperous settlements or even trade centres. These spoils of war might be later thrown back into circulation, channelled by lower-scale, more casual trade, as did Suebi according to observations by Julius Caesar (Caesar, IV.2.1, after Hughes-Brock 1993, 223). In case of the Adriatic Sea, piracy cannot be excluded, whereas in its littoral zone, one could expect brigands attacking traders, middlemen or ordinary travellers. Former phenomenon is a well-known element of the Mediterranean seafaring in the antiquity and could range from petty piracy to a more organised criminality, e.g. Cilician corsairs (Horden/Purcell 2000, 134–135, 140–143; see also De Souza 2002). Examples of the latter practice are provided by Amarna letters, describing dangers lurking on the road for the Babylonian merchants (Bryce 2002, 88–89). Taking into account the limitations in access to amber sources, described practices probably played secondary role in comparison to trade. Nevertheless, it should be reminded that social history of exchanged/traded goods ‘is of far greater overall importance than the practical significance of the activities that they represent might suggest’ (Horden/Purcell 2000, 149).

1.2.2. Biographies, travels, itineraries of things: approach to material culture

Amber is said to have had a number of qualities appealing to people since prehistory. They have been discussed over and over by a constantly growing roster of scholars, however often without explicitly stating theoretical foundations of their reasoning. If for them the issue seems obvious and not worth of expounding, I feel compelled by achievements in the field of anthropological and archaeological theory to clarify my approach to material culture.

From one perspective on the cultural setting of amber, finds made from this material can be simply reduced to the category of imports. Its sources are spatially restricted, and in most cases it was necessary to carry it over considerable distance from the place of acquiring to the place of use and subsequent deposition (voluntary or involuntary like in cases of different archaeological contexts, e.g. grave, waste pit, house floor, etc.). In a very basic understanding of the issue, one can say that unique things (materials, items) are likely to have a high status or value. However, things that may seem exotic or valuable to a community in one place could be common and, thus, little appreciated to the other, especially when the latter has it in abundance. One should not overlook significance of the road by which an import travels; the distance from the place of origin or manufacture to the final destination can contribute greatly to an object’s value (Cline 2005, 45). Or as J. Chapman puts it, ‘by travelling far, a hitherto mundane object was transformed into something special whatever the means of movement’ (2008, 335).

However, the definition of import itself is not simple,¹⁵ and assuming its commercial side might unfairly supplant the other aspects that amber could have possessed (as has been done in publications treating amber simply as a commodity European north could offer in exchange for locally unobtainable resources, such as copper, tin, etc. Earle et al. 2015). Still the import, whatever its definitions are, is only ‘one side of the coin’ in a multidimensional (or ‘multivalent’) character of amber artefacts, or any other objects that archaeologists are faced with. Too little attention has been paid to inter- and intra-contextual meaning of amber, i.e. the different ways of its adoption and adaptation by people of various places and cultures. While adoption means accepting and using something previously unrelated to its new owner as it is, adapting implies modification to suit better the new conditions and needs. The point of interest here is what value, meaning or functionality – aspects which contribute to the object’s status – amber could have for different communities, and how these were created? Arguably what it requires in order to understand the status of an amber object is to pay attention to intra-contextual interplay of humans, things, features and meanings at the place of amber deposition. Approach involving these aspects is advocated by the growing group of archaeologists studying the inflow of goods to the Mycenaean Greece (cf. Maran/Stockhammer 2012a). These scholars contest the use of generalising designations such as ‘exotic’ or ‘prestige’ imposed on objects, as they ‘suggest a semantic stability which cannot be taken for granted’ (Maran 2013, 147). One of the issues resurfacing in the debate on amber in the prehistoric communities are the ways of its appropriation – a term nowadays burdened with negative connotations, however not necessarily meaning unlawful or harmful obtention (cf. Maran 2013). As J. Maran writes, ‘in dealing with the appearance of foreign traits, the focus of attention must be placed on clarifying the ways of appropriation on a local level and on how, in the course of their integration into existing practices, new cultural forms were created’ (Maran 2012, 64).

One of the foundations for the modern archaeological theory is that human individuals are actively using material culture as an expressive symbolic medium for their social strategies and negotiations (Hodder 1982, 1986). Furthermore, it relies on the conviction that primordial societies, as entities constituted by the local transmission of traditions, inherited knowledge and various regional specificities, manifested their culture through materials which by the ways of exchange and trade travelled over distances (Hahn/Weiss 2013, 6). However, once an object leaves its place of origin (in social terms) and enters a new context, it might end up performing a function and assuming an identity that the original manufacturer never expected or intended it to have. Such a change in function and identity might result in the object either increasing or decreasing in value and status in the new environment as compared to the old one (Cline 2005, 47). The transformation described above is caused by the agency of social actors, who come into interaction with objects, either rejecting them or incorporating them into existing system of values and world views upon which particular social structure is based (Maran 2012, 63). But how can we catch a glimpse into the status of an object, if it is constantly travelling and morphing?

H. P. Hahn calls for focusing on the ‘micro-contexts on the local level’ in order to determine how foreign cultural forms are integrated into a new environment, and see if they follow patterns of practice comparable to or different from those in their region of origin (2008, 199). Maran argues that the ways by which foreign traits may have been integrated can be understood ‘by carefully studying find associations in closed micro-contexts, as well by observing indications for the manipulation of objects to fit new purposes’ (2012, 64). The strategy of analysing objects inter- and intra-contextually can be called the ‘transcultural approach’ (Maran/Stockhammer 2012b, 1). In other words, ‘the effects of intercultural relations must be investigated locally, which means concentrating on phenomena of appropriation and studying how foreign cultural forms were re-contextualised through their integration in social practices and discourses’ (Maran/Stockhammer 2012b, 2). Following the reasoning path paved by its proponents, it allows to break from a paradigm of treating foreign objects only for reconstructing systems of exchange, or for chronology. In contrast, significance of such items is not derived from their transfer from one place to another as such but rather from the ways in which they were used and contextualised.

The notion of analysing an archaeological find, respectively, of its context is certainly not a young one (see e.g. Hodder 1982, 1986). However, the concept of diffusionism, consciously or not, is still rooted in many works on the subject of exchange/trade in the Bronze Age. One of the shortcomings of the diffusionist school of thought of the early 20^th century was that the appearance of the same form was taken for granted to represent the same origin and the same meaning (Maran/Stockhammer 2012b, 2). While the spread of innovations itself could have sometimes looked like the theoreticians of the diffusionism envisaged, there is too little concern about the transformation of the meanings in the process, and appropriation of objects in different environments. To escape from repeating the failures of past methodologies, one should focus on the generative, rather than the representative character of culture.

One of the most advocated and originative theoretical perspective on unfolding relationships between human and non-human agents is the Actor-Network-Theory (ANT), which found many vocal proponents among archaeologists. What it brings anew to archaeological theory is the paradigm break from anthropocentric perception of agency, in order to give a way to the so-called ‘material agency’ (cf. Knappett/Malafouris 2008). The aim is to resign from purely materialistic, on one hand, and sociological, on the other, approach to agency, and replace it with perspective in which things and agents interact leading to creation of new meanings – reification, in a psychological sense, of things and exchange of properties resulting in bringing to life hybrid agents (cf. Latour 2005). For instance, amber bead becomes an adornment upon displaying it as a part of garment, while its bearer acquires a trait of an elegant – one does not exists without the other. J. Law refers to it as ‘semiotics of materiality’ in which ‘both human and non-human “actants” are brought forward through relationality, that is, by virtue of their respective positions (as nodes) within networks of meaning’ (Watts 2008, 188; cf. Law 1999).

However, the path leading to establishing a contact between people and objects can be long and winding. B. Latour reminds us that both information, as well as objects of exchange or trade, are driven into circulation not by their inherent physical properties, which can be approximated with power to move (e.g. as in model of dispersion of bacteria, or diffusion of liquids), but by actors without who’s action the objects will stay in place (Latour 1986). Moreover, the same actors exert power which can alter an object’s appearance or semantic content. If an object derives from afar and is foreign to the people it came into contact with, its physicality itself does not warrant the maintenance of its previous semantic content. In the progression of changing social contexts in which an object is temporarily situated during its lifetime, the faithful transmission of its meaning is less probable to occur than the transformation. Latour called this process ‘translation’ that is ‘negotiation of the meanings of cultural traits received from the outside through their integration into social practice and discourses within constantly re-assembled network comprising human and non-human actants’ (Maran 2013, 147; cf. Latour 1986, 266–269). To sum up the arguments brought forward by the authors referring to ANT, the agency of material culture to actively construct or challenge social reality relies, in the first place, on human agency and intentionality of action (Knappett/Malafouris 2008, XIII).

In the last 40–30 years, there has been lots of debating on interpretation of things in terms of their histories and changing meanings, from which a number of approaches were conceived. I. Kopytoff’s seminal article The cultural biography of things (Kopytoff 1986) aims at connecting the passage of an object through different contexts to different valuations – its biography. The author denotes two opposing tendencies, which can be identified in almost all biographies of things, that he labels ‘commoditisation’ and ‘singularization’ (Kopytoff 1986, 65). A. Appadurai in the The Social Life of Things posits that objects do not have an inherent value which makes them worthy of exchanging; the latter is socially created in the process of exchange (1986, 3–4). J. Hoskins in Biographical objects: How things tell the stories of people’s lives explains how some objects become charged with meaning through their associations with specific events in people’s lives, thus making them symbols or tokens extending beyond their bare functionality and materiality (1998). To avoid implying linearity in telling the objects’ biographies, she uses the analogy of a network, with the lines symbolising particular segments in the life of people and objects, and the nodes representing mutual transformations taking places when the latter cross their paths. The notion of a network is worth of memorizing, because it will resurface frequently in the presented work. More recently H. P. Hahn and H. Weiss proposed the term ‘itineraries’ as an idea combining pathways, stations and transitions of modern-day travellers which can be transposed also onto objects (2013). The concept does not simply aim at reflecting peoples’ and objects’ mobility throughout their lives, sometimes long and complex – non-linear. Instead its goal is to visualise the passage of things through discrete stages consisting of periods of inertness which are divided by moments of rapid transformation (Hahn/Weiss 2013, 8). It is noticeable in the above given examples that the aspect of geographical mobility (as a physical movement) is approached in a manner not to overshadow other forms of cross-bordering.

Above-described approaches to archaeological finds, while certainly full of a thoughtful reflection, may seem difficult to implement – especially when attempting to trace back the origins and follow histories/biographies/travels/itineraries of multiple amber beads, which could have gone a long and a complex way from the source to the final destination. However, within the scope of this work, it seems feasible to try to disentangle and compare some characteristics of studied objects (including meaning, utility, value, status) at the last chapter of their lifetime that is immediately before and in the moment they were deposited in the ground. The idea is to do it by multi-aspect analysis of the amber artefacts themselves, and of their context. Such a procedure is carried out in chapter 2 of this book in relation to chronology and cultural attribution of the amber finds, in chapter 3 regarding the ways of amber circulation within the circum-Adriatic zone, and in chapter 4 aimed at defining social status of amber. The notion of network comes in this place not only as a useful, visual metaphor but also as a theoretical construct and an analytical tool as well.

1.2.3. Amber circulation as a part of a network (analysis)

Idea of analysing social networks is not new to archaeology; already in 1977 C. Irwin-Williams showed the potential of a network model for analysis of prehistoric trade (1977). However in the last years, it received great feedback and gained large group of supporters, applying it in different contexts.¹⁶ The approach was eventually suggested for the study of amber circulation in the circum-Adriatic zone (Harding 2013b).

Social Network Analysis (SNA) derives from sociometry which involves the measurement of interpersonal relations in small groups, often by the means of sociogram – a depiction interpersonal structure of groups as points and lines in two-dimensional space, like graphs used in mathematics (Brughmans 2013, 632; see also Freeman 2004). In fact SNA is partly founded in graph theory: it borrows the concept of a graph as a model of social interactions/relationships, utilises similar terminology and draws from mathematical operations to quantify and measure these properties (Wasserman/Faust 1994, 93, after Brughmans 2013, 628). Nonetheless, it is largely a brainchild of sociologists and still developed as an integral part within more modern sociological approaches.

In a resume, this theory assumes that relationships between entities of various kinds can be pictured as a network, which they form in the real life. So it involves searching for nodes and links among chosen entities on the basis of specific properties connecting them (Knappett 2011, 41–46; 2013b, 3). There are several principles shared by social networks analysis, among them viewing actors and their actions as interdependent rather than independent, autonomous units, and considering relational ties (linkages) between actors as channels for transfer or ‘flow’ of resources (either material or non-material) (Wasserman and Faust 1994, 4, after Brughmans 2013, 632–633). Thus the networks, at the social level, are created by actors guided by, e.g. the will to reach some material or non-material gains, as in interactions defined in the previous section as exchange and trade. Once the network is established, it facilitates similar interactions, however can also be altered by actors endowed with agency, thus contributing to the dynamic character of networks vs static structures.

Hence, the essence of applying this approach in studies of prehistory lays in discovering and defining relational patterns between spatially localised (predominantly although not necessarily) archaeological data, e.g. artefacts, features or sites (Brughmans 2013, 633; Knappett 2013b, 8). Final effect of such analysis is creation of a network model in which selected categories of sources are combined, basing on common quantitative or qualitative features (Harding 2013b, 391). Such models can differ in the level of their randomness, scale and centrality amongst others (cf. Brughmans 2013, 636–645). The model is aimed at reflecting the network which exists in reality between entities entangled in mutual relations. Yet since archaeology deals with past societies, it is more appropriate to speak of reconstructing the networks of human interactions and relationships on the basis of material culture, than real-time observations (Knappett 2013b, 7–8).

Advocates of Network Analysis (NA) argue that by using this approach, a researcher has an ability to derive conclusions directly from an archaeological material instead of imposing a priori interpretations dictated by chosen social theory (Harding 2013b, 391). Thus the inference process proceeds from analysis of sources to construction of interpretations (bottom-up), not vice versa (top-down) (Knappett 2011, 26–30). Discussed approach assumes to fully reveal specificity of the processes occurring in the micro-scale, e.g. in relation to selected regions of Europe (Knappett 2013a; Knappett et al. 2008). However, it should also be mentioned that some scholars who apply rather large-scale World System Theory took advantage of analytical procedure given above (e.g. Kardulias 1999). In fact the network can be analysed multi-dimensionally, from its constituent parts (nodes and links), through its segments (e.g. dyads, triads, etc.), to a comparison of complete/whole networks built around different entities (cf. Brughmans 2013, 625–626). NA gives a theoretical basis for the use of a wide spectrum of statistical tools borrowed from graph theory that focus i.a. on the detection of temporal and spatial correspondence of objects marked by specific characteristics. It also utilises GIS analytical methods to a great extent, allowing for more refined representation of distribution and interrelations among spatially embedded data.

NA does not enforce a single method or approach to data. There is a plethora of different applications of the concept of network and its analysis to be found in archaeological literature (see e.g. Brughmans 2013; Knappett 2013a). In the following it has been employed in a rather basic format, by visualising data related to amber in the form of a graph (network of linked entities) and analysing the latter by a set of popular but not too-advanced statistical tools. It predominantly found use in chapter 3, where relationships between typologically defined, regional assemblages of amber artefacts are analysed in order to reconstruct circulation of amber in the circum-Adriatic zone. Specific methodological solutions, together with the choice of methods and tools selected for implementation of NA, are described in the section 3.12. Still, the idea of ‘network’ in its broad theoretical meaning is largely guiding this work through its consecutive stages, up to chapter 5, where it is integrated into the concept of ‘system’.

1.3.1. What is amber?

The term ‘amber’ is rather capacious, and there are various opinions on what it designates, or how to define it. This semantic complexity is due to the fact that scholars from several different fields of research have contributed to its terminology: natural sciences (mineralogy, chemistry, geology, botany, palaeontology, etc.), humanities (archaeology, history of art, etc.), not to mention commercial aspects involved in amber (see e.g. Beck 1986; Vávra 2009a, 2009b). The most widespread and generally accepted definition of amber is based on results of chemical investigations. Amber is a fossilised tree resin made of organic compounds called terpenes, which are derived from plant exudates and undergo continuous changes as a function of specific fossilisation processes (Angelini/Bellintani 2005, 441). The fossilisation process begins with polymerisation of a wide range of isoprenoid compounds, primarily terpenoid acids and alcohols that are secondary plant metabolites. The resulting crosslinked copolymer is subjected to further changes influenced by factors such as age and burial history, collectively described as ‘maturation’ (Vávra 2009b, 446–447).

In the preceding definition, ‘amber’ refers to all fossil resins of different origins and properties. Originally the term ‘amber’, and its German equivalent bernstein, was exclusively referring to the fossil resin of Northern Europe that is now more sharply defined by the mineralogical designation ‘succinite’ (Beck 1986, 58).

Not all resins fossilise – some are not preserved at all, while others are sometimes a mixture of non-polymerizable terpenoids (Vávra 2009b, 447). Currently known fossil resins are thought to originate from several different source trees, all of which are believed to be extinct today (Beck 1986, 67–68). In fact, there are only two types of living trees that produce resin capable of becoming amber: the Kauri pine (Agathis australis) and some species belonging to the legume Hymenaea family (Caldararo et al. 2013, 46; cf. Ross 1998).

According to K. B. Anderson and J. C. Crelling, amber and fossil resin should be defined as ‘solid, discrete organic materials found in coals and other sediments as macroscopic or microscopic particles, which are derived from the resins of higher plants’ (Anderson/Crelling 1995, 11–12). Before a resin turns into amber, it goes through a series of transformations with intermediary stages of different properties and chemical structure. A number of terms have been used to describe the early stages of fossilisation of resins: beginning with ‘modern or recent resins’, ‘ancient resins’ and ‘subfossil resins’, leading finally to terms like ‘fossil resins’, ‘ambers’ or ‘resinites’, the latter ones with a minimum age of 40,000 years (cf. Anderson 1997). Ancient and subfossil resins have often been collectively grouped as ‘copal’ – a special stage of diagenetic change of plant exudates, although still used with different meanings, also as a synonym for amber (Vávra 2009a, 214–215).

1.3.2. Amber and copal – differences

On the onset of polymerisation process, photo-initiated when the plant exudates are exposed to sunlight, the resin hardens rather quickly and the volatile components dissipate. In the course of progressing polymerisation and loss of volatile components, referred to as ‘maturation’, the resin changes its character from ‘recent’ to ‘fossil’ (Caldararo et al. 2013, 46). Resins that have not yet undergone all the steps of fossilisation, like polymerisation and maturation, are usually designated as ‘copals’ – unfossilised resin (Vávra 2009a, 214–215). However, there is no single criterion to judge, whether an analysed sample completed this transformation or still is at an intermediary stage.

Some authors suggest use of geological age of the sediments containing amber as a chronological indicator, proposing 40,000 or 1,000,000 years as minimum age to consider a resin as fossilised (see Anderson 1997; Langenheim 2003). On the other hand, according to G. O. Poinar (1992), resins may preserve the properties characterising copal for as long as 3 or 4 millions of years. Later, the same author placed all fossil resins from Quaternary deposits, or those up to 1.6 million years old, in the category of copal since they do not have the chemical or physical properties of amber (Poinar 1999, 151). P. C. Rice stated age of copal can vary from 1,000 to 100 years old (1993, 220), while D. A. Grimaldi claims that the process of transformation of a resin into amber is not determined by specific time span (Grimaldi 1996, 16). It seems that differentiating between copal and amber solely on the basis of the geological age of sediment is highly problematic and may lead to contradictory conclusions (Vávra 2009b, 447). Hence, N. Vávra argues that ‘copal’ should be used as a collective term for any non-fossilised resin material, whatever its geological age, with the exception of copal older than Holocene that should be called ‘fossil copal’.

A different stance in this debate is adopted by palaeoentomologists and palaeobotanists, who use the term ‘fossil’ in reference to living entities of the geological past, whatever its state of preservation may be and generally agree that the inclusions in copal, when present, are of extant, not extinct species (Rice et al. 2000, 5; Vávra 2009a, 214).

Another criterion, this time geographical, is presented by B. Kosmowska-Ceranowicz, who defines copal as ‘subfossil resins from the southern hemisphere, which are of different age and origin’ (Kosmowska-Ceranowicz 1999, 95). This view stands in compliance with modern spatial range of vegetation of trees producing resins capable of fossilisation, which have already been subjected to elaborate studies (cf. Rice 1993; Grimaldi 1996). Poinar listed countries where copal appears in abundance: Colombia, Dominican Republic, Kenya and Madagascar, usually reaching an age between 65,000 and 50 years (Poinar 1999, 151).