Human Mobility and the Spread of Innovations – Case Studies from Neolithic Central and Southeast Europe

3.1.1 The Information Flow

In her fundamental work on the conditions of agricultural growth, published in 1965, Esther Boserup described the significance of a growing population density for the adoption of new agricultural techniques (Boserup, 1965, pp. 116–118). During the last decade, more general studies dealing with the interrelationship between demographic factors and innovation as well as innovation transfer emphasised the significance of demographic growth and cultural connectivity for both processes (e.g. Powell, Shennan, & Thomas, 2009, p. 1301). A closer look on calculations of population density and demographic growth in the areas north and south of the temporary border shows, however, that a significant increase in population density in Northern Central Europe and South Scandinavia does not occur before the beginning of the fourth millennium BCE but rather during the first half of the fourth millennium BCE (in TRB contexts), that is to say, several centuries after the beginning of food production (e.g. Hinz, Feeser, Sjögren, & Müller, 2012; Shennan & Edinborough, 2007; Shennan et al., 2013, p. 4, Figure 3). Müller for example calculates for South Scandinavia and Central Europe a value of 0.8–0.9 inhabitants per square kilometre before 4000 BCE, i.e. the late Ertebølle culture, and an increase to 1.3 inhabitants per square kilometre after 4000 BCE, i.e. the TRB culture (Müller, 2013, pp. 494–500). Therefore, demographic change cannot be identified as a trigger for innovation transfer, rather it might be considered a long-term consequence of the adoption of agriculture.

Next to demographic developments, changes in mobility patterns, that might have facilitated the information flow, have to be taken into account. Statements on human mobility are often based on isotope analysis (strontium as well as oxygen isotopes). As the glacially formed landscape in South Scandinavia does not exhibit major regional differences in the strontium isotope signature, studies based on these methods are rare and relevant results do not exist for the period under consideration (Frei & Frei, 2011; Frei & Price, 2012; Price & Frei, 2015; see also Price, 2022 for a critical discussion on strontium isotopic provenancing in Denmark). Another way of gaining insight into mobility is carbon and nitrogen isotopes. The δ¹³C and δ¹⁵N values on human bones document a regular mobility between coastal and inland areas for the Mesolithic Ertebølle groups. This is reflected by individuals buried on Mesolithic inland sites, showing a marine diet (Fischer et al., 2007, pp. 2145–2146). Everyday mobility within Ertebølle groups is much more variable, however. Research in South Scandinavia and Northern Germany support various forms of mobility. Johansen (2006) for example discusses cyclical rotation between larger camps along the sea shore and smaller camps with varying functions for today’s area of Jutland. The movement of small groups along lakeshores where they stayed for a longer period of time before they moved on to the next place is discussed for the area of Schleswig-Holstein (summarised in Hofmann et al., 2022, pp. 278–282). For the subsequent Neolithic (TRB) phase data, e.g. isotope values, or more nuanced interpretations of the archaeological record on mobility, are rare which is why further consideration for this later period – and in this context also further considerations on the development of mobility during the Mesolithic–Neolithic transition – remain speculative. However, the increase in imported goods from the area south of the temporary border (see below) reflects the integration of the northern TRB culture into supra-regional networks. The situation south of the border in the distribution area of the MBK (Figures 1 and 2a), on the other hand, is clearer. Interestingly, here an increase in mobility can be traced from the end of the fifth millennium BCE onwards, i.e. shortly before the innovation spread to the north. The archaeological record is characterised by short-lived settlements, lasting no longer than 5–10 years, by far-reaching exchange networks and highly mobile individuals as the analysis of six individuals from Heidelberg-Handschuhsheim in southern Central Europe shows (Seidel, 2017; Turck, Kober, Kontny, Wahl & Ludwig, 2014). The Sr-values of six individuals from three generations show repeated moves on a regional scale (Turck et al. 2014). So far, this is the only site within the distribution area of the so-called Michelsberg culture, which has been analysed with this method. Therefore, future work will show whether these mobility patterns can be assigned to a wider context. However, the state of research on the MBK available so far clearly shows that individuals and small-scale social groups (settlement communities) are characterised by a certain degree of residential mobility.

This finding of a probably very mobile MBK population south of the temporary border corresponds with an increase in imported objects which originated south of the border and were deposited north of the border within Mesolithic Ertebølle contexts as well as early Neolithic TRB contexts. A diagram published by Lutz Klassen, who has counted all imported objects distinguished per time slice of about 200 years, shows that the number of imports, for example shoe-last adzes, between 5500 and 3500 BCE is characterised by a massive increase during the last centuries of the fifth millennium and the first centuries of the fourth millennium BCE, that is in a time when early agriculture started to spread northwards across the temporary border (Klassen, 2004, Figure 71). Obviously, the intensity of contacts increased considerably at that time. For these contacts and exchange networks various forms of mobility are discussed. Klassen interprets the presence of imports as a result of down-the-line exchange from farmers to foragers (Klassen, 2004, pp. 262–267). It is equally conceivable, however, that these objects travelled with immigrants from the south (Sørensen, 2013) or that highly mobile hunter-gatherer-individuals travelled south to obtain these objects (see also Hofmann et al., 2022, p. 279).

Klassen’s analysis, however, reveals another interesting aspect: first exchange networks between the farmers inhabiting the Central European Loess belt and the hunter-gatherer-fisher population in Northern Germany and South Scandinavia already existed during the last centuries of the sixth millennium BCE, i.e. between the LBK and Ertebølle culture (Klassen, 2004, Figure 71). This means that contact and communication already existed one millennium before agriculture was adopted. This leads to the question, why those early contacts did not push the adoption of the innovation. On the one hand, this could be explained by the fact that these contacts were of minor significance and intensity. On the other hand, one could discuss – and this leads us to our next point the second crucial element of innovation transfer – whether the Mesolithic Ertebølle groups north of the border were not able or were unwilling to adopt/integrate this early mode of agriculture practiced in the LBK and Middle Neolithic in Central Europe at that time, into their own way of subsistence.

3.1.2 Adoption and Integration

In the next step, the conditions and context for adoption and integration of agriculture is described, first and foremost environmental parameters like soil, temperature, and precipitation, that constitute essential conditions for plant growth.

During the LBK and the Middle Neolithic, agriculture in Central Europe, south of the border, was focused on fertile Loessic soils. The area of Northern Central Europe and South Scandinavia, i.e. north of the border, however, is characterised by glacially formed, morainic landscapes. Those are characterised by a mosaic of different soil types, like heavy loams or sand dunes, some more and some less suitable for the cultivation of early weeds like emmer and einkorn (e.g. Behre, 2008). When agriculture started to spread northwards however, something in the agricultural techniques and practices south of the border had changed. First, a diversification of soils – i.e. the integration of less suitable soils into Neolithic settlement areas – and a diversification of cultivated cereals can be documented in Central Europe from c. the middle of the fifth millennium BCE onwards, i.e. the Middle Neolithic and MBK (Kirleis & Fischer, 2014; Lüning, 2000). A diversified cereal spectrum is also reflected in the early TRB farming sites in Northern Central Europe and South Scandinavia. While Einkorn played only a minor role in the TRB, tetraploid free threshing wheat and barley gained significance – both more robust when confronted with less favourable conditions (e.g. drought or cooler temperatures; Dreibrodt, Zahrer, Bork, & Brauer, 2012 on climatic variability; Kirleis & Fischer, 2014, p. 89 on growing conditions of free threshing wheat); it is only later, when agriculture was finally established in the North, that again a standardisation of cereal cultivation – with a focus on emmer and barley – was documented (Kirleis & Fischer, 2014, p. 91). Second, a diversification of agricultural techniques and practices had developed during the second half of the fifth millennium BCE. For barley, for example, a cultivation as a summer grain is discussed which might have been more favourable for the prevailing regional growing conditions (Zimmermann, Meuers-Balke, & Kalis, 2007, pp. 42, 51). Moreover, a growing significance of slash-and-burn cultivation and possibly also a growing significance of animal husbandry (pastoral turn acc. to Schier, 2020, p. 60) is discussed for the second half of the fifth millennium BCE (Gerlach, Baumewerd-Schmidt, van den Borg, Eckmeier, & Schmidt, 2006; Schier, 2009, p. 26, Figure 3). As experiments on slash-and-burn cultivation have shown, the ash of the burnt wood does not only increase soil fertility due to mineralisation – what makes this technique ideal for less suitable soils – but also increases the temperature near the ground due to its dark colour (so-called albedo; see Ehrmann, Rösch, & Schier, 2009; Schier, 2009). The latter might not only have been important for the regional climate in the north but also because of the global climatic changes documented for this time period: at that time, the optimal climatic conditions of the Atlantic ended and the Subboreal period with its slightly colder temperatures and drier conditions started (e.g. Behre, 2008, pp. 56–57; Blankholm, 2008, p. 107; Zvelebil, 2006, p. 179). However, I would not consider this climatic change as a trigger for the spread of agriculture to the North, since domestic animals and cereal cultivation played only a minor role during the early phase of the TRB. I rather suggest that new types of cereals and agricultural techniques and practices facilitated the spread of farming economy since they were more suitable for the morainic soils and therefore yielded a good return.

Moreover, slash-and-burn does not require an intensive, year-round effort as it is reconstructed for the early agriculture (horticulture) on Loessic soils practiced by LBK and Middle Neolithic communities (Schier, 2009, p. 34). Therefore, the new techniques and practices might have been easier to integrate into the established subsistence system, based on foraging and fishing. As the archaeological record clearly reflects, the traditional subsistence strategies still played a significant role during the early Neolithic, after the adoption of agriculture (Sørensen & Karg, 2014, Figure 13; Schmölcke, 2022).

The next point to consider is the social structure and the system of values on both sides of the temporary border before and after the spread of early agriculture. Archaeological interpretation is often based on burials and grave goods in this context. Regular burials from both areas before and after the time of innovation transfer are mostly absent, however. Data on settlements are likewise rare as mainly surface scatters of settlement refuse for the Ertebølle and TRB are documented (e.g. summarised in Müller, 2017). For the MBK in Central Europe, settlement sites are rare, too, and – except for some pit houses at the site of Echzell-Wannkopf (Höhn, 1996, Figure 4) – characterised by a small number of pits (summarised in Seidel, 2017). For the MBK, therefore, ditched enclosures serve as a basis for inferences on the social structure. By some authors they are interpreted as a reflection of a hierarchic society as their construction is considered to be only feasible when coordinated by a leading person (e.g. Gronenborn, 2010; summarised in Jeunesse & Seidel, 2010, pp. 68–69). However, the opposing standpoint argues that their construction does not need established leaders but that MBK enclosures can likewise be interpreted as communal constructions that help to support social cohesion of a – rather egalitarian – society mainly living in dispersed hamlets and small villages (see e.g. Jeunesse, 2010, p. 53; Jeunesse & Seidel, 2010, p. 68). This is supported by the observation that well-documented enclosures show quite short utilisation times, 10–30 years, which contradicts the existence of an established power (Seidel, 2008, p. 385). Another source for discussing social structure in MBK society is exceptional objects, first and foremost being jadeite axes. ibid. Due to the use of exotic raw material from distant sources (south alpine region near Monte Viso and Monte Begua), the use of a highly aesthetic raw material, and the production of elaborated forms – jadeite axes can be very large and at the same time very thin (e.g. axe from Geitelde with a length of 44.4 cm, Klassen, Cassen, & Pétrequin, 2012, p. 1302) which is why those specific examples have not had a functional character – they are interpreted as prestige goods or status goods (e.g. Pétrequin, Cassen, & Klassen, 2010, p. 194). As a closer look on the find contexts shows, however, they are only known as stray finds or hoards but not as grave goods. Therefore, they can be considered to have been highly esteemed objects but they do not mark established power structures. Therefore, I’d rather interpret them as part of a wider phenomenon – a growing appreciation of exotic goods and connected to this of far-reaching communication networks. This is supported by small, short-lived settlements that also contradict a strict vertical social structure.

North of the temporary border, established power structures also cannot be documented, neither before the beginning of food production (Ertebølle-contexts), nor after the Mesolithic–Neolithic transition (early TRB contexts). For Ertebølle contexts specific categories of objects, like Limhamn axes, specific types of ornaments or projectiles (summarised in Klassen, 2004, pp. 225–230) show regionally limited distribution areas that are interpreted as territories. Since the borders of these territories are not stable, they do not reflect established power structures but are rather interpreted as territories of kinship groups (Klassen, 2004, p. 229; see also Hofmann et al., 2022). This is also the case for the early TRB. Therefore, in both areas, no established social hierarchies can be documented. Next to settlement patterns, the role of imported exotic goods like copper items or jadeite axes as prestige goods has been discussed in the context of social patterns in Ertebølle and early TRB societies (e.g. Klassen, 2004, pp. 262, 264). A closer look on the total number of these exceptional finds shows that their number is lower than one might expect, particularly in the area north of the border. In the northern provinces of Germany and Denmark, a total of 21 copper objects and 12 adzes made from jadeite were counted by Klassen, dating to a period of 700 years (4300 and 3600 BCE; Klassen, 2004, 262, 264.). Although this number is influenced by taphonomic processes and depositional habits of the past communities, it is surprisingly low. Rather than reflecting established elites acting in this area, who used these objects as status symbols or prestige goods they also seem to reflect the wider phenomenon of a growing appreciation of exotic goods and an increasing significance of far-reaching communication networks.

At the same time, the societies on both sides of the temporary border have developed economic systems that are characterised by diversity and thus by a certain degree of flexibility. If we assume that the system of values is reflected and shaped by everyday practice, this high diversity and flexibility might have facilitated the communication between both areas and thus the slow and stepwise integration of food production into societies in Northern Central Europe and South Scandinavia.

3.2.1 Factors Influencing the Information Flow

As mentioned before, according to the current state of research copper metallurgy developed in Southeast Europe around 5000 BCE. As described above, the Vinča settlement site of Belovode/Serbia yielded the oldest slag known so far. From this region it spread towards today’s area of Hungary, the Alföld (Tisza-Herpály-Czőszhalom complex) and Southeast Transdanubia (= southeastern distribution area of the Lengyel culture), during the first half of the fifth millennium BCE where it stopped for several hundred years (Figure 5; Rosenstock et al., 2016; Scharl, 2016, 2019). A closer look on the find contexts of traces of copper metallurgy and copper objects shows a concentration of finds on tell settlements of the Tisza-Herpály-Czőszhalom complex, while they are missing from co-existing small flat settlements of the same cultural context (see e.g. Bánffy, 2010, p. 149; Raczky & Anders, 2010, p. 144 for Polgar-Czőszhalom). In the neighbouring distribution area of the Lengyel culture, copper finds mainly come from extensive horizontal settlements (e.g. Aszód, covering 25 ha at the minimum, or Zengővarkony, covering 15 ha; see Kalicz, 2001, p. 160; Raczky & Anders, 2010, p. 143) and large cemeteries (e.g. Alsónyék-Bátaszék, Zengővarkony or Aszód; see e.g. Kalicz, 2001, pp. 159–160; Osztás, Zalai-Gaál, & Bánffy, 2012, p. 390) which concentrate in Southeast Transdanubia (Kalicz, 2001, pp. 158–159; Scharl, 2016, Table 2).

By contrast, the northwestern distribution area of the early Lengyel culture is characterised not only by a lack of copper artefacts or copper metallurgy but also by small settlements and a lower settlement density. Extensive cemeteries have not been documented so far, and evidence for burials is scarce (Scharl, 2016). This picture hints at a certain interrelation between demographic aspects and the spread of copper metallurgy: The high concentration of people within tell settlements in the Great Hungarian Plain and extensive “flat sites” west of the Danube may have stimulated the use of copper, as well as other exotic goods like spondylus, obsidian, or clay figurines known from these sites (Siklósi, 2004, 2013; Scharl, 2016, p. 232). This idea builds upon previous investigations dealing with the interrelationship between demographic factors and innovation as well as innovation transfer as they emphasised the significance of demographic growth and cultural connectivity for both processes (Henrich, 2010; Powell et al., 2009). Tell settlements and extensive “flat sites” may have constituted focal points for the development of interest in copper artefacts while low population densities in the northwestern part of the Lengyel culture may have hampered the spread of copper metallurgy by delaying the flow of information. The correlation between a high population density and a substantial quantity of copper tools can be explained by two factors. First, a higher number of individuals represent a higher number of information carriers and potential adopters, thus enhancing the information flow. Second, the organisation of communal life is influenced by the number of “participants.” High population densities, therefore, may have stimulated the development of forms of social organisation in which the use of exotic objects was highly valued (socially and/or ritually). In this context, the adoption of copper metallurgy and copper objects and the use of other exotic material took on a greater significance (Scharl, 2016, p. 232). Another factor, constraining the spread of copper metallurgy towards the northwestern Lengyel culture was probably also the structure of the supra-regional exchange networks that reflect various forms of mobility along established routes of communication and exchange. This becomes visible in an extensive survey by Katalin Kovács in which she compiled finds of various lithic raw materials, marine molluscs (such as spondylus shells), and copper during the Late Neolithic in the Carpathian Basin. As the spatial distribution patterns of these finds show, Southeastern Lengyel settlements were connected to eastern networks, i.e. the Tisza-Herpály-Czőszhalom complex – while the networks between the two areas of the Lengyel culture (southeast and northwest) are only weakly documented. Rather, the northwestern settlements were orientated towards the north. These northern connections ran along the northern Tisza river and its confluences, the rivers Sajó/Slaná, Rima, Ipel, and Zagyva (Kovács, 2013, pp. 386–388, Figures 1–5, 395; Scharl, 2016, p. 234). Moreover, the distribution pattern of Szentgál radiolarite from the Bakony mountains hints at strong networks between northwestern Transdanubia, north of the Balaton, and neighbouring areas in the north and northwest like Moravia and Slovakia (Regenye, 2013, pp. 559–560). The networks were probably based not only on small-scale mobility between neighbouring settlements but also on medium- to long-distance mobility of individuals (see also Kovács, 2013). They probably ran along river systems that were mainly oriented north-south and also along overland routes, e.g. the foot of the northern Mountain range for the obsidian exchange network (Regenye, 2013, p. 389). Therefore, the Neolithic landscape and topography was probably an important factor influencing the course of routeways (see e.g. contributions in Bell, 2020) and might have hampered intensified east-west connections. Since this mobility served, among other things, the supply of raw materials, it can be assumed that the movements and encounters were not one-time events, but that they occurred repeatedly and ran along familiar routes (see O’Brien, 2021 on the process of landscape learning). Therefore, social interactions on these routes were probably characterised by social intimacy. This can e.g. be discussed for the supply with various types of lithic raw materials (see Kovács, 2013, pp. 389–394). Since copper, on the other hand, seems not to have played a significant role in the networks of northwestern Transdanubia it could not establish itself either. Though this is only one way of interpreting the spatial distribution pattern of various raw materials and objects. Taken together, the exchange networks reflect a clear separation of the settlements within the Lengyel culture by their integration into these networks which might have hampered the flow of information between both regions. However, as mentioned before, common practices in pottery production or the sporadic use of copper in the northwestern distribution area of the Lengyel culture do reflect a certain mobility and flow of information between both areas no matter how rare it was. Therefore, factors that might have hampered the adoption and implementation of the innovation have to be taken into account.

3.2.2 Adoption and Implementation

If we look at the conditions constraining the integration of copper as an innovation, we can look at differences in various spheres of daily life between both areas. Subsistence strategies, for example, do not exhibit any profound differences between the southeastern and the northwestern Lengyel settlements. In both areas, the same type of soils (Loess soils) were used and agriculture, based on growing cereals and animal-husbandry, was predominant (Bánffy, 2010, pp. 150–151). The most obvious difference is the settlement size and, moreover, the burial rites. Both hint at differences in social structure and value systems between the two regions. In this context, it is noteworthy that the area north of the Lake Balaton is characterised by hills while the landscape to the southeast is predominated by gentle slopes and plains. It is therefore entirely conceivable that the former prevented the concentration of population as it is observed in Eastern and Southeastern Transdanubia (Scharl, 2016). By contrast, the population concentration in tell settlements east of the Tisza as well as in extensive horizontal settlements west of the Danube might have triggered the development of social complexity and systems of value different from those in the small and dispersed settlements in Northwest Transdanubia. This does not imply the existence of social elites, a distinct socio-political hierarchisation or the existence of an institutionalised central authority, as some authors assume (e.g. Hansen & Toderaş, 2010, pp. 101–103; Siklósi, 2013, p. 430), since complexity is not necessarily related to hierarchy and executive power alone (see e.g. Dobres, 2000, p. 121; Kienlin, 2012, p. 18; Wynne-Jones & Kohring, 2007, p. 3). Analysis on late Neolithic and early Copper Age settlements in Hungary rather seem to reflect kin groups as the basic social unit of the Late Neolithic (Kienlin, 2015, p. 27; Parkinson, 2002, pp. 416–417, Table 3). Copper metallurgy, therefore, is interpreted as part of a long-standing communal interest in ornaments and pigments in these segmentary societies (see Kienlin, 2015, p. 31 with further references). Based on these assumptions, copper metallurgy and copper use would have been integrated into the value systems, social, symbolic, economic, technological as well as ritual spheres that had developed over centuries within tell communities and probably also within the extensive horizontal settlements of the Lengyel culture based, amongst other things, on an interest in specific colours. In this context, the use and working of copper was already integrated into everyday practice. Since it is mainly implements and ornaments (made not only from copper but also other exotic material) that were deposited, copper cannot be interpreted as prestige good. Moreover, the production and use of copper heavy tools, which often are interpreted as prestige goods (see below; e.g. Klassen et al., 2012, p. 1299), do not gain momentum before c. 4600/4500 BCE, i.e. after the end of most tell settlements in the Carpathian Basin (Link, 2006, pp. 44–46, Figures 20–22; Rosenstock et al., 2016, p. 73).

In short, in the tell settlements and the extensive flat sites, not only exotic goods like copper, but also spondylus, dentalium, or exotic lithic raw materials were highly valued as finds from burials and deposits reflect, while all this is lacking in the northwestern Lengyel settlements. At the time, when copper was finally adopted in the latter area, however, the social structure in the Alföld and Southeast Transdanubia had changed. Tell settlements and extensive flat sites had disappeared and were replaced by small dispersed settlements and a more mobile way of life (Tiszapolgár and later on Bodrogkeresztúr culture). This may have stimulated communication, since the pronounced differences in social structure between the two areas became somewhat less marked (for a more detailed description see Scharl, 2016). At the same time, copper in the areas southeast of the temporary border (Tiszapolgár culture) gained a different meaning in this period. While in the first half of the fifth millennium BCE copper was mainly used to produce small implements and ornaments, the production of heavy tools gained importance around 4500 BCE. And this is the time, when copper metallurgy starts to spread further north. Obviously, copper axes and adzes were of interest for the communities in the northwestern Lengyel culture and beyond, since we find these objects even in Central Europe at that time. This is, however, part of a wider phenomenon concerning an increasing significance of axes and adzes in Europe in general (Klassen et al., 2012, Figure 1). This transformation is also reflected in the changing role of axes and adzes in the burials of the Lengyel culture. In its early phase, axes and adzes made from stone or sometimes antler and frequently exhibiting traces of use were deposited in burials of all sex and age groups (Lichter, 2001, p. 249). However, around 4500 BCE, stone axes became more elaborate and lost their functional character, exhibiting no traces of use anymore. According to Zalai-Gáal, they gained importance as prestige goods or symbols of power (Zalai-Gaál, Gál, Köhler, & Osztás, 2011, p. 80; Zalai-Gaál, 2012, pp. 497, 501). Around 4500 BCE, these exceptionally elaborate artefacts are mainly found in the graves of male adults. These are furnished with further exceptional grave goods and sometimes exhibit elaborate burial architecture, like grave 3060 from the Alsónyék cemetery shows (Zalai-Gaál et al., 2011). This transformation of patterns of use and depositional patterns hint at a different meaning of these objects from c. 4500 BCE onwards. It seems that axes and adzes made from stone, copper, or antler were charged with social meanings that underline the prominent role of the male individuals who received them as grave goods. This change in meaning might have facilitated the adoption of copper metallurgy in the northwestern Lengyel culture.