Radiocarbon Dated Trends and Central Mediterranean Prehistory

The evidence for human activity during the Mesolithic period in the central Mediterranean (c. 9700 to 6000 BC) varies by sub-region. On the Italian peninsula, Mesolithic settlement largely occurred in caves and rock-shelters and is broadly characterized by the earlier ‘Sauvetterrian’, and later ‘Castelnovian’ lithic industries (or the ‘first’ and ‘second’ Mesolithic in French literature), whilst the surrounding islands are associated with undifferentiated lithic traditions (see Lo Vetro & Martini, 2016). Northern Italy has a particularly well-documented Mesolithic, and settlement evidence demonstrates use of both lowland and upland or mountainous territories (see Fontana & Visentin, 2016), with sites known in the Trieste Karst, Adige Valley, Tuscan-Emilian and eastern Ligurian Apennines, and Po Plain (Biagi et al., 1988; Franco, 2016; Kompatscher et al., 2016; Scoz et al., 2015; Visentin & Carrer, 2017; Visentin et al., 2014, 2016). In central and southern Italy, local terrestrial and marine resources appear to have been exploited in a pattern consistent with the seasonal utilization of coastal caves and rock-shelters (Lo Vetro & Martini, 2016). In general, however, earlier Mesolithic settlement in the south shows particular focus on coastal areas, as on the Salento peninsula in Puglia, in contrast to greater exploitation of inland areas in central (Pluciennik, 2008) and northern Italy (Fontana et al., 2013).

Among the islands of the central Mediterranean, Sicily has some of the most important Mesolithic sites. A cluster of well-studied cave sites with Mesolithic occupation and burial is known in north-west Sicily (D’Amore et al., 2010a, 2010b; Lo Vetro & Martini, 2016; Lo Vetro et al., 2016; Tagliacozzo, 1994), whereas in southern Sicily the comparative dearth of Mesolithic activity (Martini et al., 2007) resembles the situation in the Maltese Islands, which have no evidence for Mesolithic occupation (Bonanno, 2000). In Sardinia and Corsica, the Mesolithic period is similar to that of peninsular Italy, although marked differences that stem from the natural isolation of the two islands are reflected in the archaeological record. Settlement of the Tyrrhenian islands is defined by short-term and discontinuous occupation of small coastal rock-shelters (Costa et al., 2003; Lugliè, 2009a), although Mesolithic presence in larger caves is documented in Sardinia (Lugliè, 2009a, 2018). The Mesolithic economy of Sardinia and Corsica reflects exploitation of local terrestrial and marine resources, with a significant reliance on the endemic small mammal Prolagus sardus (Vigne, 1998). It has been suggested that, taken together, the evidence indicates short-term seasonal visits to the islands by small sea-faring groups from the Italian mainland (Costa et al., 2003).

The end of the Mesolithic was also regionally varied. In southern and central Italy, there appears to be a clearer chronological gap between the last Mesolithic hunter-gatherers and the arrival of the first Neolithic farmers (Perrin & Manen, 2021; Pluciennik, 1997), while the situation is considerably more varied in the north. Along the northern cost of the Tyrrhenian Sea, an area without any late Mesolithic sites spanning western Liguria and eastern Provence lies between the Rhône valley and the eastern Ligurian Apennines where later Mesolithic sites are documented (Battentier, 2018; Biagi et al., 1988; Maggi et al., 2020). This distinctive pattern of late Mesolithic activity appears to have had a major bearing on the settlement pattern of northern Italy’s earliest Neolithic pioneers, who spread along coastal routes, favouring areas without Mesolithic hunter-gatherers (see below). In the rest of northern Italy, along the Po and northern Apennines, the available radiocarbon data reveal a much murkier picture, and it is difficult to prise apart the relationship—and potential interactions—between the earliest farmers and last hunter-gatherers in the region (Martínez-Grau et al., 2020; Pearce, 2013, pp. 159, 204–207; Perrin & Manen, 2021).

The transition to agriculture in the central Mediterranean in the run-up to the sixth millennium BC brought with it technological innovations, new belief systems, domesticated animals and traditional ‘Neolithic package’ crops (Guilaine et al., 2019; Malone, 2003; Ucchesu et al., 2017). The earliest Neolithic settlements in Italy associated with impressed-ware ceramics have been found along the lowland coastal areas of south-east Italy on the Salento peninsula and Tavoliere of Apulia (Brown & Alexander, 2013; Natali & Forgia, 2018). The region is perhaps best known for its many large ditch-enclosed settlements (villaggi trincerati) (Delano Smith, 1978; Jones, 1987), and with some 774 such sites of varying size documented on the Tavoliere alone (Whitehouse and Hamilton, 2020, p. 163), the Neolithic of southern Italy marks a point of major population increase and settlement density. The majority of ditched villages consisted of small groups of ditch-enclosed farmsteads set within larger perimeter ditches spanning areas of 4–7 hectares, but mega-sites such as Passo di Corvo reached up to 130 ha (Tinè, 1983; Trump, 1987, pp. 118–129). The Neolithic then rapidly spread westward into Calabria (Morter, 2010) and Sicily (Leighton, 1999, pp. 66–74; Natali & Forgia, 2018). In Sicily, Neolithic settlement was contained within caves and in open-air ditched village sites along the northern and southern coasts. Most of the known Sicilian open-air villages were excavated in the late nineteenth and early twentieth century along the south-eastern coast of the island (Orsi, 1899, 1921) and have received little attention since. Only a few later village sites located further west, such as at Stretto-Partanna and Piano Vento, have undergone more systematic investigation (Castellena, 1985; Martínez Sánchez et al., 2016). Most of our understanding of the Early Neolithic in Sicily therefore stems from two cave sites in western Sicily—Grotta dell’Uzzo and Grotta d’Oriente—where transitional Neolithic–Mesolithic stratigraphy has been identified (Tagliacozzo, 1994; Lo Vetro and Martini, 2016).

The spread of the Neolithic to central and northern Italy can be viewed as a series of parallel maritime expansions along the Adriatic and Tyrrhenian coastlines, including Sardinia and Corsica (for detailed discussion see Pearce, 2013, pp. 21–158). The speed at which agriculture spread northwards is demonstrated by the extremely early introduction of the Neolithic to western Liguria and eastern Provence by as early as 5900 cal. BC (Binder et al., 2017; Maggi et al., 2020). In Adriatic central and northern Italy, where the spread of agriculture was intertwined with its spread along the adjacent eastern Adriatic coasts of Albania, Montenegro and Croatia (Conati Barbaro, 2019, pp. 71–83; Ferrari et al., 2018; Forenbaher & Miracle, 2005), the Neolithic arrived several centuries later (Martínez-Grau et al., 2020). This combination of routeways for the spread of the Neolithic into northern Italy resulted in the development of regionally distinct cultural traditions that can be divided between the north-western Italian Ligurian Impressed wares, and the Vhò, Fiorano, Gaban and Fagnigola groups to the east across the Po and Alpine valleys (Starnini et al., 2018). In central Italy, Early Neolithic settlements are found in subcoastal areas and lowlands on terraces overlooking rivers and lakes (Conati Barbaro, 2019, p. 13; Fugazzola Delpino et al., 2003a, pp. 94–99; Radi et al., 2018; Malone et al., 1992), whereas the settlement pattern in the north is one of cave and rock-shelters in the west and open-air villages in the east (Bagolini, 1980; Pessina & Tinè, 2018), further echoing the west–east differentiation in cultural traditions for the North Italian Neolithic.

In Sardinia, the arrival of the Neolithic around 5800–5600 cal. BC also saw complete genetic and cultural discontinuity with the preceding Mesolithic, as attested by stratigraphic information from Grotta Su Coloru (Lugliè, 2009b, 2018), radiocarbon data (Perrin et al., 2021), and aDNA studies (Modi et al., 2017). Together with the suggestion that Mesolithic activity on Sardinia and Corsica may have been restricted to occasional visits by groups from the Italian mainland (see above), this may therefore indicate that the Tyrrhenian islands were largely—if not entirely—depopulated by the time the earliest Neolithic settlers arrived. Following an initial Neolithic pioneer phase, the Neolithic in Sardinia signalled a period of significant settlement expansion, as indicated by the number of archaeological sites especially on the west coast, whilst, by contrast, Early Neolithic expansion in Corsica was more muted (Lugliè, 2009b, 2018).

Narratives of the Middle and Late Neolithic describe how gradual economic diversification and pastoralism occurred in increasingly dispersed and varied settlement contexts (Barker, 1999, pp. 13–14; Dolfini, 2020, p. 515; Malone, 2003, p. 299). Whereas areas of previous intense human occupation in southern Italy and Sicily—namely the Tavoliere and Catania plains—declined (Leighton, 1999, pp. 53–54; Fiorentino et al., 2013; Skeates, 2015; Whitehouse, 2013), there was expansion into a variety of upland and lowland areas, but also into small islands. The Maltese archipelago was settled by 5500 cal. BC, with occupation in both caves (Despott, 1917) and open-air settlements (Brogan et al., 2020; McLaughlin et al., 2020b, pp. 154–155; Trump, 1966b, 2015). In the larger islands of Sardinia and Corsica, Middle and Later Neolithic human occupation spread into a range of inland and coastal lagoon areas (Dyson & Rowland, 2007, pp. 36–37). Within central Italy, Middle and Late Neolithic settlement continued in subcoastal areas but also penetrated further inland to the Apennine valleys and wetland areas (Fugazzola Delpino et al., 2003a, pp. 97–99; Malone, 1994, 1994a, 1994b, pp. 67–80). A similar situation occurred further north, with open-air settlement expansion into wetland zones and into the upland Alpine and Apennine areas (Mottes et al., 2009; Skeates, 2013, p. 8; Visentini, 2006).

The fourth and third millennia BC broadly correspond to the Copper Age in the central Mediterranean (Final or Late Neolithic in French and Maltese literature) and are defined as a period of social and economic transformations which developed out of the later Neolithic. The settlement record for the Italian Final Neolithic and Copper Age is spotty at best, but in general the period saw a movement away from nucleated villages towards more dispersed settlement into a wider variety of landscape settings (Dolfini, 2015, pp. 30–33, 2020, p. 517) and continued expansion into upland zones—where the latter narrative has been driven further by the discovery of the Tyrolean Iceman in the Ötztal Alps (Barfield, 1994b; Spindler, 2000). Traditionally, the lack of open-air settlement for Copper Age Italy was explained within the mid-twentieth-century culture-historical framework as evidence that the period was characterised by nomadic ‘warrior pastoralists’ who migrated into the central Mediterranean and introduced metal working into the region (Trump, 1966a, pp. 79–80; see Robb, 2007, p. 288; Dolfini, 2020, p. 524). Barker (1981a) was the first to argue against the ‘warrior pastoralist’ narrative, and discoveries of numerous settlements over the last 20 years (largely thanks to developer-led archaeology) further refute the long-held view that Copper Age settlement was ephemeral and suggest that the role of transhumant pastoralism during the period has been over-emphasized (Cardarelli, 2015, pp. 154–156). Settlement evidence for the central Mediterranean Copper Age has changed drastically, particularly in the central-southern Italian peninsula (Anzidei et al., 2007; Baioni & Poggiani-Keller, 2013; Giola et al., 2007; Tunzi et al., 2013), and several substantial domestic sites indicate that larger stable settlements endured throughout the Copper Age (Anzidei et al., 2016; Bernabò Brea et al., 2011; Fugazzola Delpino et al., 2003b; Manfredini, 2014; Salerno and Marino, 2011). Many Italian sites also show continuity from the Late Neolithic to the Early Bronze Age (Baioni & Poggiani-Keller, 2013; Fugazzolo Delpino et al., 2003a, p. 101; Ingravallo, 1980; Silvestrini & Pignocchi, 1997; Talamo, 2006), suggesting relative homogeneity in settlement patterns throughout the fourth and third millennia BC.

The north Italian Copper Age was traditionally associated with the Remedello culture that extended across the Po Valley (Barfield, 1971). As is the case with much of the central Mediterranean, systematic research in recent decades has shown that the archaeological record is in actual fact considerably more nuanced (De Marinis, 1997). To the south of the Po River, inhumation cemeteries and settlements are found associated with the Spilamberto Group (Bagolini, 1981; Miari, 2014; Miari & Benazzi, 2018; Miari et al., 2017) and to the north the Civate Group is known from burial in caves and statue menhirs in the Alpine regions (Barfield, 1983). Copper Age settlement in northern Italy appears on fluvial terraces and on the slopes of the pre-Alps, where multi-stratified sites demonstrate long occupation histories spanning the duration of the Copper Age (e.g. Lovere-Colle del Lazzaretto and Monte Covolo in Lombardy: Baioni & Poggiani-Keller, 2013). Similarly long occupation spans also occur in the inner Alpine valleys, as at Latsch, Vinschgau (Festi et al., 2011), which are exploited from the Late Neolithic onwards (Putzer et al., 2016). Copper Age settlements also occurred on the southern Po Plain, with some focus on the margin of the Apennines in Emilia-Romagna (Bernabò Brea et al., 2011; Berni et al., 2011; Miari, 2014).

The Rinaldone culture traditionally defined the central Italian Copper Age (Trump, 1966a, pp. 72–80), although recent research has shown the complex spatial and temporal relationship between Italy’s traditional Copper Age ‘cultures’ in central and southern Italy (see Fig. 2). Areas such as the ‘core’ Rinaldone zone on the Tuscany–Latium border still lack definitive settlement evidence (Fugazzola Delpino et al., 2003a, pp. 100–101), but a large number of sizeable cemetery sites suggests considerable population increase during this period (Negroni Catacchio, 2006; Negroni Catacchio et al., 2016). Some of the most important developments have occurred in the area south of Rome, where excavations have uncovered extensive evidence for Copper Age settlement in the area between the Tiber river and the Colli Albani and redefined the entire Copper Age sequence for central-southern Italy (Anzidei et al., 2007, 2012, 2016; Carboni & Anzidei, 2013; see Anzidei & Carboni, 2020) by revealing the complicated spatial and temporal relationships between the Rinaldone, Gaudo, Laterza and Ortucchio ceramic styles (Fig. 2). The Roma-Colli Albani sites indicate dense and stable settlement in southern Rome from the mid fourth to late third millennia BC, alongside continuity in economy and burial traditions across the entire Late Neolithic and Copper Age sequence. On the Adriatic coast of central Italy, Copper Age activity is known in Marche along the narrow coastal plains surrounding Ancona and into the Apennines, with funerary sites situated towards the coast and settlement located inland (Fugazzola Delpino et al., 2003a, p. 101; Manfredini et al., 2009; Skeates, 1997). Large open-air villages are also known in Marche at Conelle di Arcevia (Cazzella & Moscoloni, 1999; Cazzella & Recchia, 2014) and Maddalena di Muccia at Macerata (Manfredini, 2014) and attest to the existence of substantial and stable Copper Age settlement here too.

The southern Italian Copper Age was until recently known solely from large rock-cut tomb cemeteries associated with the Gaudo culture in Campania and the Laterza culture in Apulia (Biancofiore, 1967; Whitehouse & Renfrew, 1974, pp. 349–357). The Roma-Colli Albani sites mentioned above have highlighted the complexities of the Copper Age in southern Italy too, extending the distribution of Gaudo and Laterza ceramic styles to central Italy, and as actually reflecting chronologically discrete cultural horizons—Gaudo representing the middle Copper Age and Laterza representing the recent Copper Age (Carboni, 2020a, p. 89, 2020b; Carboni & Anzidei, 2013, pp. 149–161; Fig. 2). The recent introduction of a new earlier Taurasi phase associated with cremation cemeteries in Campania (Passariello et al., 2010), Apulia and Basilicata (Aprile et al., 2013; Quarta et al., 2014), further demonstrates the true complexity of the south Italian Copper Age. In Campania, Middle Copper Age settlements from the early third millennium BC are situated on the fertile coastal plain north of Naples (Aurino, 2013). At the settlement of Caivano, two successive phases of occupation associated with the Gaudo culture were separated by the Agnano 3 eruption horizon (Passariello et al., 2010), demonstrating a rapid reoccupation of the area following the event. The settlement record for later prehistory in Campania also shows general consistency from the Late Neolithic to Early Bronze Age, with settlements known in both lowland and upland areas, with those in the highlands appearing to relate to the control of natural route ways (Talamo, 2006). In Apulia, Copper Age activity on the Tavoliere was minimal, and Final Neolithic–Copper Age settlements are found on the Murge plateau (Fiorentino et al., 2013), the Salento peninsula and Basilicata (Pacciarelli et al., 2015). The picture for the Late Neolithic and Copper Age of Apulia has started to improve in recent years, and the recent excavation of a settlement at Tegole represents a rare and important Copper Age presence on the western margin of the Tavoliere (Tunzi et al., 2013, 2017).

Turning to the islands, the Sicilian ‘proto-Eneolithic’ during the late fifth to early fourth millennia BC is largely associated with the development of rock-cut tomb cemeteries in the south related to the San Cono–Piano Notaro culture, such as Piano Vento (Castellana, 1995) and Scintilia (Gullì, 2014), and with the Conca d’Oro culture in the north (Tinè, 1960). Copper Age settlement sites in Sicily show utilization of a variety of landscape locations, and like adjacent areas of peninsular Italy, there was continuity with Late Neolithic and Early Bronze Age patterns (Leighton, 1999, p. 100). The period is characterized in general by an expansion into the uplands (Leighton, 2005), apparent in both the earlier Copper Age (Cazzella & Moscoloni, 2012, pp. 59–62) and middle and later Serraferlicchio and later Malpasso cultural contexts (Giannitrapani et al., 2014; Malone et al., 2003). In southeast Sicily, areas of dense Early Neolithic settlement on the coastal plains surrounding Syracuse and Catania remained largely unused during the Copper Age (Leighton, 1999, pp. 89, 100), but use of cave sites for habitation, burial and cult purposes continued in the coastal areas of Agrigento in southwest Sicily (Gullì, 2011).

In the Sardinian Copper Age, it appears that Early Copper Age Sub-Ozieri and Middle Copper Age Abealuzu and Filigosa settlement shows general continuity with the Late Neolithic Ozieri phase (Melis, 2000, p. 141; Melis, 2009), which is also reflected in continuity in funerary traditions (Melis, 2014). Interpretation of the details of Copper Age settlement patterns in Sardinia should, however, proceed with some caution, given the stylistic similarities in material culture across the Late Neolithic and earlier Copper Age and the fact that most sites are known from either surface features or find scatters (Webster & Webster, 2017, p. 57). The chronology of the Sardinian Copper Age has received much-needed attention in recent years (Melis, 2013; Melis et al., 2017), but many questions remain over the spatial and temporal interplay between cultural phases in the third millennium BC. More recently, Pearce’s (2017) updated chronology (see Fig. 2) has expanded the Ozieri phase to 4200–3400 cal. BC and Sub-Ozieri to 3600–2800 cal. BC. By the early third millennium BC, the Filigosa and Abealzu phases emerged alongside the distinctive Monte Claro phase, which spanned the majority of the third millennium BC and overlapped with the Sardinian Bell Beakers (Melis, 2013, pp. 206–207). Marked differences in settlement and material culture are more apparent in Monte Claro phase contexts (Melis, 2000, p. 144), with the emergence of large villages in some cases consisting of up to 60 huts, as at Monte Pranu (Manunza et al., 2014). In general terms, Monte Claro phase settlements were primarily located on lowlands in the south and hills to the north, in contrast to the coastal settings of earlier periods (Lai, 2008, p. 102).

Finally, the fourth and third millennia BC on the Maltese Islands saw the rise of a complex culture characterized by elaborate and sophisticated megalithic ‘temples’, art and ritual processes that expressed a strong local identity (Bonanno et al., 1990). The sharp cultural discontinuity between the Early Neolithic (Għar Dalam and Skorba phases) and the Late Neolithic ‘Temple Period’ has been the focus of much discussion (Trump, 2002, pp. 238–241), establishing a theoretical framework that suggested cycles of relative isolation and insularity over time (Stoddart et al., 1993; Trump, 1961); this has since been challenged (Grima, 2002; Robb, 2001), and then reiterated in both cultural and biological detail (Malone & Stoddart, 2004; Ariano et al. in press). Domestic evidence for the Temple Period on the Maltese Islands is extremely scant (Malone et al., 2009), in contrast to a wealth of ritual architecture (Trump, 2002). Aside from unconvincing arguments that subsidiary structures at megalithic sites represent huts (Sagona, 2015, pp. 55,78), only two Temple Period domestic structures have been excavated in the archipelago, both on the smaller island of Gozo (Malone et al., 1988, 2020a).

The Italian Bronze Age has been divided into four phases, Early, Middle, Recent and Final. Traditions of scholarship dictate that the Bronze Age of northern Italy has been studied in the context of its close ties with broader continental Europe (Barfield, 1994a). The north Italian Early Bronze Age is represented by the Polada culture, noted for numerous lake settlements distributed along the southern Alps, particularly along Lake Garda, and limited settlement on the Po Plain (Barfield, 1994a; Capuzzo, 2014; Nicolis, 2013). This settlement pattern changed greatly throughout the mid second millennium BC in the Middle Bronze Age, which was marked by the rise of the Terramare system. The Terramare was accompanied by a dense settlement shift to the central-southern Po Plain and considerable population increase (Bernabò Brea et al., 2018; Vanzetti, 2013), which reached a peak at the turn of Middle Bronze Age and Recent Bronze Age (Cardarelli, 2009, p. 468). The Terramare settlements were essentially planned villages of pile-built houses that were serviced with drainage and enclosed within quadrangular banks (Pearce, 1998). By the Recent Bronze Age, the Terramare settlements had become more complex, showing greater monumentality in their earthworks, which implies a necessity for defence, alongside technological advancements in metallurgy and agriculture (Bernabò Brea et al., 1997; Blake, 2014).

A subsequent decline of the Terramare system led to an eventual collapse at the end of the Recent Bronze Age (Cardarelli, 2009, p. 485); however, this collapse was not universal, since some Terramare north of the Po River continued into the Final Bronze Age (Cupitò et al., 2015). The decline of the Terramare is associated with a large-scale demographic collapse (Cardarelli, 2009; Rondelli, 2008), caused by a variety of factors, including environmental decline and climatic deterioration (Cremaschi et al., 2006, 2016; Whitehouse, 2001) or social and political instability (Cardarelli, 2009, p. 471). Overall, the region inhabited by the Terramare group has limited evidence for much of the Final Bronze Age and Early Iron Age (Barfield, 1994a), with the exception of the Valli Grandi Veronesi sites (Cardarelli, 2009, p. 506). A similar abandonment of Recent Bronze Age settlements is attested in other areas of the Peninsula, such as the Romagna plain (Von Eles & Pacciarelli, 2018) and a substantial part of the Marche region (Cardarelli, 2009, p. 507). Recent authors (Pearce, 2020; Stoddart, 2020c; Zamboni, 2021) have also sought to consider the extent to which the Terramare actually reflected a form of ‘fragile’ proto-urbanism in the later Bronze Age that deviated from the typical model of Mediterranean urbanisation, which revolved around long established centres.

Central Italy is an example of this ‘typical’ process, where the Bronze Age is defined by gradual development in social and political complexity that ultimately led to state development in the Iron Age (Bietti Sestieri, 2010, pp. 356–358; Pacciarelli, 2000; Stoddart, 2020a, 2020b). Although interpretation must proceed with caution because of the methodological and geographical biases implicit in the data (Stoddart, 2020a, pp. 13–22), central Italy is nonetheless the best-resolved Italian region. Most of the work has been concentrated on South Etruria (Northern Lazio) (Barbaro, 2010; Di Gennaro, 1986; di Gennaro & Pacciarelli, 1992), Latium vetus (Southern Lazio), the area close to Rome (Cardarelli, 2018), and the Marche on the Adriatic coast (Cardarelli et al., 2017), although notable exceptions such as Gubbio, in Umbria, have some of the highest densities of pottery in the region (Malone and Stoddart, 1994).

The social and political transformations of the Bronze Age were clearly accompanied by an increase in archaeological sites and population (Barker, 1999; Barker & Stoddart, 1994), which has been corroborated by the available radiocarbon evidence (Palmisano et al., 2017). Settlement patterns for the Early and Middle Bronze Age of central Italy show occupation of both upland and lowland areas as part of a mixed economy (Barker, 1981b, 1999, 2005). The Recent Bronze Age in Italy corresponds to a period of profound social and political change, and it has been argued that it is under-represented in the archaeological record, especially through surface survey (Barker & Stoddart, 1994). This pattern of demographic growth continued to develop into the Final Bronze and is associated with a general increase in sites, in contrast to northern Italy. Increased density of settlements and associated cemeteries in South Etruria during the Final Bronze Age has also been interpreted as evidence for increasing social hierarchy (Barbaro, 2010; di Gennaro & Barbaro, 2008) and cultural homogeneity, recognized as Proto-Villanovan material culture and latter attested in a significant part of the Italian peninsula (Negroni Catacchio, 2010). A further profound change took place at the transition to the Iron Age in Etruria, when settlement concentrated on larger plateaux or alternatively neighbouring hills with a significant extension of 125–180 ha or 40–90 ha in case of smaller centres (Pacciarelli, 2000, p. 279); in some cases (e.g., Tarquinia) these were already occupied from the last phase of the Final Bronze Age (Bietti Sestieri, 2010). There has been much discussion regarding the politics of how this process was accomplished, with interpretations ranging from collective action to the authority of a restricted leadership (see Stoddart, 2010; Stoddart et al., 2020).

For the southern part of the central Mediterranean, the picture of the Bronze Age is one of considerable regional diversity. Early Bronze Palma Campania villages in the south of the peninsula show varied use of settlement locations, including coastal and riverine areas, lowlands sites and mountain camps (Di Vito et al., 2019; Talamo, 1996), indicative of small societies engaged in mixed agriculture and small-scale pastoralism (Albore Livadie, 2007; Di Vito et al., 2019). Evidence from the exceptionally well-preserved settlement of Nola-Croce del Papa in Campania shows a reliance on ovicaprines, pig and cattle, alongside active food storage (Albore Livadie & D’Amore, 1980; Albore Livadie and Vecchio, 2020). Traditionally, Early Bronze Age occupation of Campania was thought to have been severely impacted by the Avellino Pumice eruption of c. 1935 to 1880 cal. BC (Albore Livadie et al., 1998; Passariello et al., 2009), with some sites showing delayed reoccupation only in the Middle Bronze Age (Di Lorenzo et al., 2013; Di Vito et al., 2019), although recent research has also demonstrated considerable continuity and rapid resettlement of the area following the eruption (Albore Livadie et al., 2019).

Major sites such as Toppo Daguzzo (Basilicata) and La Starza (Campania), located between environmental zones on communication routes, seem positioned as important or central places (Malone et al., 1994a, 1994b). Excavations at Poggiomarino, Campania, have revealed a significant wetland site that was established during the Middle–Late Bronze Age and persisted into the Iron Age (Albore Livadie et al., 2010; Price, 2013), showing the presence of large and complex settlements in southern Italy during the second millennium BC, echoing the pattern known from further north. During the Middle Bronze Age, settlement is variable throughout southern Italy although there is significant use of cave sites and shelters for ritual, funerary and seasonal purposes, one of the most significant being the Grotta Cardini di Praia (Bietti Sestieri, 1997). Sites on the coast are also widespread, particularly in the Adriatic and Ionic regions, whilst fortified sites in Apulia, such as Roca Vecchia and Coppa Nevigata (Alberti, 2013b), and Broglio di Trebisacce in the Sibaritide (Peroni and Trucco, 1994), may have been connected with increased maritime trade at the time. In the Late Bronze Age, a pattern similar to that of central Italy occurred, in that the numbers of sites increased, and focus shifted to sites in naturally defensible locations (Malone et al., 1994a, 1994b).

The Sicilian Early Bronze Age is represented by the Castelluccio phase when settlement expanded to defended sites located inland, associated with increasing pastoralism, and some coastal settlements (Malone et al., 1994a, 1994b; Leighton, 1999, p. 114, 2005). On the Aeolian Islands, as the Early Bronze Age Capo Graziano phase progressed, there was a shift to settlement on higher ground (Alberti, 2013a; Leighton, 1999). On Malta and Gozo, the transition from the Temple Period to the Bronze Age now appears to be characterised by the appearance of an intermediate ‘Thermi ware’ phase and a subsequent hiatus before the start of the Early Bronze Age Tarxien Cemetery phase (McLaughlin et al., 2020a, 2020b, p. 33), when levels of activity on the islands are much reduced. For Sardinia, the defining feature of the Bronze Age is the Nuragic period (Lilliu, 1963; Webster, 2015), which saw a massive population increase and settlement expansion across the island. The Nuragic period is defined by its eponymous architectural feature, the nuraghe, consisting of a large conical tower, with later nuraghi featuring multiple towers and a large number of subsidiary structures. Early Nuragic sites, or proto-nuraghi, tend to be distributed in western-central Sardinia, north of Cabras (Demurtas & Demurtas, 1992), before the tradition expanded across the entire island. As the Nuragic period developed during the Middle to Recent Bronze Age, settlements increased in number, size, and elaboration, culminating in complex nuraghi (Depalmas, 2009a,2009b,2009c; Melis, 2017), such as at Su-Nuraxi/Barumini. With an estimated 7000 nuraghi found across Sardinia (Klob, 2005), the Bronze Age in Sardinia is seen as a period of considerable population increase, similar to northern Italy. Although nowhere else hosts such elaborate sites in such high densities, parallel traditions to the nuraghi occur in other western Mediterranean islands, such as the Torre of southern Corsica (Peche-Quilichini & Cesari, 2017), Sesi in Pantelleria (Orsi, 1899) and Talayots on the Balearic Islands (Gili Suriñach et al., 2006). In the Maltese Islands, villages associated with the Middle Bronze Age Borġ in-Nadur phase were located within large walled enclosures that also recall this wider tradition (Evans, 1971; Tanasi and Vella, 2011).

The end of the prehistoric period in the central Mediterranean was a complex set of transformations brought about by the indigenous development of pre-Roman Iron Age states in central Italy (Pacciarelli, 2000; Perego & Scopacasa, 2016; Peroni, 2000; Stoddart, 2020a, 2020b, 2020c), increasing presence of Phoenician and Greek colonies in southern Italy, Sicily, Sardinia and the Maltese Islands, and Italic and, later, Gallic settlement of the northern parts of the central Mediterranean region. The cultural homogeneity that characterized the Final Bronze Age then dissolved, giving way to distinct regional cultural groupings (Riva, 2010). This regional diversity, generated by special chains of networks and relationships (Bietti Sestieri, 2012; Blake, 2014; Di Gennaro, 1996), and increasing entanglement in wider worlds, also saw economic transformation and significant changes in patterns of agriculture, land use and settlement. The archaeological evidence for this period takes many forms and is not easily summarized; but in general terms there was a greater degree of long-distance trade, centralized authority, nucleated settlement and technological sophistication than in any preceding period. From this patchwork of independent, and sometimes competing social units, Rome in the eighth Century BC rose to dominate first central Italy, then the entire central Mediterranean region, culminating in a civilization that spanned much of Europe, North Africa and the Middle East. Rome’s political and cultural legacies were so pervasive that they are still strongly felt throughout the world today.

The method used here for calculating radiocarbon kernel density models is one of a range of similar approaches that aggregate radiocarbon data and visualise their inherent trends. A KDE model can be interpreted much like a histogram representing the number of dates falling within a time slice or ‘bin’, which is analogous to the bandwidth of the KDE. Whilst a histogram consists of counts of dates within fixed breakpoints, the KDE is a continuous function that creates a smoothing effect that is naturally better at resolving sudden changes (Fig. 3) and is therefore our preferred means of visualising these data. Furthermore, because each calibrated date has a large range of uncertainty, bootstrapping techniques must also be employed to develop a confidence envelope for the counts of each histogram bar. As Fig. 3 demonstrates, not only is the uncertainty of the histogram greater, but subtleties in the data are also more difficult to identify.

A closely-related alternative is the use of summed probability distributions, which are very often used to summarize sets of radiocarbon dates. The summing approach can be criticized on the grounds that spurious artefacts are introduced into the sums via the idiosyncrasies of the calibration curve. However, the latest refinements in smoothing and bootstrapping have moved towards addressing these issues. Compared with the KDE or histogram (Fig. 3), the summed probability distributions contain more calibration noise, and although this can be removed with locally-estimated scatterplot smoothing algorithms (LOESS modelling), we prefer the KDE approach as the underlying assumptions in the smoothing model are easier to relate to real-world conditions.

The KDEs were numerically differentiated in order to calculate annual average growth rates (see Supporting Information document pp. 21–22). The radiocarbon database, and the R code used to undertake the analysis are included in this paper as electronic supplementary information, which also contains some supplementary analysis and alternative projections of the data.

The KDE models suggest that there was little overall variation in the level of Mesolithic human activity in the central Mediterranean as a whole, other than a very gradual increase over time. Activity models for mainland Italian regions, Sardinia and Sicily for the period 10,000 to 6000 cal. BC are given in the Supporting Information document (pp. 6–7). These models indicate a degree of fluctuation in most regions, and occasionally significant differences from the overall picture, but given the relatively small sample sizes, these patterns could also be the product of differential preservation and other sources of bias. A weakly significant spike in activity in Sicily around 7700 cal. BC is due to a tradition of burial in caves and long-term occupation that is both archaeologically visible and well researched at a number of sites in the northwest of the island (D’Amore et al., 2010a, 2010b; Lo Vetro & Martini, 2016; Lo Vetro et al., 2016).This could, on some level, reflect the underlying demography but further investigation of this phenomenon is something we leave for future work. It would be possible to extract all open-air settlement sites from the database and analyse them separately, for example, to see whether they conform to a similar trend, although reducing the size of the dataset reduces its statistical power. Similarly, decreasing levels of activity in the mid eighth millennium BC in central Italy are interesting, especially since the climate and landscape were still in a state of post-glacial flux, transitioning from the Boreal to Atlantic phases of the Holocene.

In general, however, any features and trends in the radiocarbon record of the central Mediterranean before c. 6000 cal. BC are quite weak and reflect an archaeological record that is for the most part defined by short-term occupation in rock-shelters and caves across the central-southern peninsula (Lo Vetro & Martini, 2016; Pluciennik, 1994, 2008) and the surrounding islands (Costa et al., 2003; Lugliè, 2009a). The notable steady state of the density models for much of the Mesolithic period does not show the long-term increase in activity that would be expected under a model of stationary growth coupled with the underrepresentation of older sites due to taphonomic bias (Surovell et al., 2009). In the case of the central Mediterranean, this trend is most likely due to the predominance of cave sites, which are not subject to the same taphonomic processes as open-air sites.

The transition to agriculture is clearly visible as a sharp increase in the gradient of the KDE density models (marked ‘A’ in Fig. 4), reflecting the rapid population growth and settlement density that is associated with the European Neolithic. This process did not occur simultaneously across the central Mediterranean, but once it became manifest, a similar trajectory of gradually rising then declining activity played out. In southern Italy and Sicily, the transition is first signalled in the KDE models around 6200 cal. BC, but in central Italy, southern France and the Tyrrhenian Islands it occurred later, between 5900 and 5800 cal. BC. The Neolithic reached the Maltese archipelago around 5500 cal. BC; however, activity on the islands declined around 5200 cal. BC and soon faded away entirely. New multi-proxy evidence from Malta and Gozo suggests either abandonment of the islands during this time, or a low population size and substantial landscape reorganization that left a limited trace on the island’s landscape (Grima et al., 2020, p. 228; McLaughlin et al., 2020a, p. 31). Although aDNA studies have been lacking for the region until recently, current evidence from central Italy (Antonio et al., 2019), Sicily (Fernardes et al., 2020) and Sardinia (Modi et al., 2017) shows that central Mediterranean Neolithic groups conform to wider European trends by showing typical Anatolian farmer ancestry, indicating that the transition to agriculture in the region was indeed characterised by the movement of people who introduced the Neolithic way of life. The peaks in the KDE models and their timing likely reflect the demographic signature of a ‘travelling wave’ as suggested by Silva and Vander Linden (2017) for the European Neolithic, with a ‘boom’ in emigrants followed by a ‘bust’ in immigrants (see below for discussion on wider Neolithic Europe).

In most regions, the pronounced increase in Early Neolithic activity reaches a peak several centuries after the introduction of farming (identified ‘B’ in Fig. 4). In central and southern Italy, this occurred at 5500 cal. BC, 5300 cal. BC in Corsica and Sardinia, and 5200 cal. BC in the Maltese Islands. The staggered dates for this high point of activity in Corsica, Sardinia and Malta match the pattern of later introduction of the Neolithic to these islands and suggest that the Neolithic cultural phenomenon followed a similar trajectory in these places, but at different times, further exemplifying the ‘boom and bust’ characteristic of the Early Neolithic in Europe (Shennan et al., 2013). Nowhere is this more pronounced than in southern Italy, where the signal of intensification and subsequent decline is primarily driven by sites on the Tavoliere plain in Apulia.

The ditched villages of the Apulian Tavoliere have traditionally defined the Neolithic of southern Italy (Delano Smith, 1978; Pessina & Tinè, 2018). Whilst it is clear that the ditched villages were not all occupied at once, the Tavoliere represents the densest area of settlement anywhere in Neolithic Europe (Brown, 2003), which peaked in the mid sixth millennium BC (Fiorentino et al., 2013; Parkinson & McLaughlin, 2020), representing a major demographic event in an area with no Mesolithic presence in the preceding centuries (Perrin et al., 2021). This archaeological evidence for population increase and dense settlement activity is clearly reflected in the KDE models (Fig. 4) and animated maps (see Supplementary Information). Comparisons between historic or modern population growth rates and those derived from the radiocarbon data therefore provide a particularly useful benchmark against which the results can be interpreted (see Supporting Information, pp. 21–22). In the case of southern Italy, growth associated with the Early Neolithic started around 6200 cal. BC and increased by approximately 0.7 ± 0.2% per year, which is less than the current global population growth rate of 1.09% and estimations for the wider European Neolithic, but similar to modern growth rates in the USA (Table 5). Our results indicate that the peak of the southern Italian Neolithic occurred between 5700 and 5450 cal. BC and signals a major demographic event, before the region entered a phase of slow decline akin to population decline rates in modern Japan (Table 5). According to Skeates (2000b), the following 5500 to 5250 cal. BC period is considered a phase of continuity among the ditched villages of the Apulian Tavoliere, with the radiocarbon evidence suggesting a general backdrop of declining activity levels and settlement intensity. In central Italy, an Early Neolithic peak occurred at 5500 cal. BC, and although this was followed by a reduction in activity, the decline was much more gradual than it was in the south.

The eventual abandonment of the Tavoliere, so visibly apparent in the KDE models for southern Italy and animated maps, has been hypothesized to be the result of possible land exhaustion and overpopulation that led to settlement expansion into nearby valleys (Malone, 2003, pp. 252–253; Whitehouse, 2013). Fiorentino et al. (2013) identified a wet period that occurred on the Tavoliere between 6200 and 5500 cal. BC, which was followed by a dry period, coinciding directly with the growth and subsequent decline observed in the KDE analysis presented here. This may suggest that favourable climatic factors played a major role in shaping the southern Italian Neolithic, and that a mixture of overpopulation, land exhaustion and climate probably triggered a decline in human activity and settlement in the area. This observation is corroborated by a second spike in the KDE model for southern Italy during the later Neolithic at around 4500 cal. BC (Fig. 4, point C), which corresponds with a second brief wet period recorded on the Tavoliere by Fiorentino et al. (2013).

In northern Italy, our results show how the transition to agriculture played out in a markedly different way, characterised by an initial period of relatively rapid growth which slowed at 5500 cal. BC before finally peaking around 4800 cal. BC. However, when viewed at a sub-regional level, the results illustrate the stark differences between north-western and north-eastern Italy during the Early Neolithic (Fig. 7). The early arrival of the Neolithic in the north-western region of Liguria is apparent in Fig. 7 (Binder et al., 2017; Maggi et al., 2020) and contrasts with the much more muted introduction of agriculture towards the north-east on the Po Plain. These regional differences have long been acknowledged in the cultural setting of the Early Neolithic of northern Italy, which is characterized by a variety of regional ceramic traditions (Malone, 2003, p. 251) including the Ligurian impressed wares—which display a visible influence from southern Italy—and, to the north-east, the Isolino, Fiorano, Vhò, Gaban and Fagnigola groups on the Po and in the Alpine valleys, which so clearly stand apart from the broader central-western Mediterranean context. Rather than directly relating to the broader Impressed-Cardial complex that characterises the Early Neolithic of the central-western Mediterranean, the ceramic traditions of north-eastern Italy have been argued to be influenced by Adriatic or central Italian traditions (Biagi et al., 2020, pp. 194–195; Pearce, 2013, p. 204). The evidence for continued Mesolithic presence in parts of northern and central Italy has also been cited as a factor in how the Neolithic played out in this part of Italy and its timing (for discussions see Binder, 2000; Pearce, 2013, pp. 206–207), but overlaps between Mesolithic groups and Neolithic groups now seem less likely (Martínez-Grau et al., 2020). In terms of settlement, the record for the Early Neolithic of the Po Plain area is scant, in strong contrast to the south, with much of the evidence stemming from the so-called fondi di capanna, large storage pits previously considered to be hut foundations (Biagi et al., 2020), and the results of the KDE and animated map seem to illustrate this general picture. There are therefore still significant issues pertaining to the mechanisms behind the introduction and subsequent trajectory of the Neolithic into the central/north-eastern areas of Italy, the timing of which was perhaps additionally influenced by climatic factors and differences in physical landscape. Ultimately, these can only be resolved by future research and targeted radiocarbon dating in the Adriatic area, as well as further consideration of the eastern shore of the Adriatic, which is vital to this story, and is currently the topic of further research by the authors.

The availability of databases of radiocarbon dates for neighbouring regions (RADON and BANADORA) also allows for comparisons to be drawn between the central Mediterranean and other European regions (Figs. 8 and 9). Although there are obvious differences in timing, the comparison demonstrates that southern Italian settlement patterns in the Early Neolithic were very similar to those on the opposite side of the Adriatic. Likewise, there are commonalities between subsets of these European regions throughout time. For example, the northern Italian apogee of 4500 cal. BC was also manifested less prominently, but still significantly in southern Italy (Fig. 4, point ‘C’), and is also apparent in the records from south-eastern France, Iberia and Germany. The German case was associated with the final phases of LBK culture and the conclusion of 600 years of growth. In northern Italy, the increase at 4800 cal. BC is related to the widespread distribution of Middle Neolithic VBQ/Square-Mouthed Pottery sites across the region (Mottes et al., 2009; Visentini, 2006), which are well documented in the Ligurian caves, but also by a density of sites on the central Po Plain. Later, a widespread spike in activity early in the fourth millennium BC can be detected in central Italy, Switzerland, Germany, France, Scandinavia, Britain and Ireland. There are differences in the timing of this spike, which again allow us to visualise the ‘boom and bust’ and ‘travelling wave’ characteristics of the European Neolithic at the continental level (Shennan et al., 2013; Silva & Vander Linden, 2017). That said, almost everywhere saw a downturn in the mid fourth millennium BC.

Comparisons with North Africa (north of 13°N) can be made using the archaeological radiocarbon dataset published by Manning and Timpson (2014). This dataset captures the continental-scale demographic transformations brought about by the start and end of the African Humid Period (8500 to 3500 cal. BC) and, importantly, a temporary decline in activity spanning 5600 and 4700 cal. BC. In addition, the more detailed database published by Lucarini et al. (2020) of African sites in Mediterranean regions can be used to compare regional European patterns with those in Africa (Fig. 10). Whilst the sparse nature of the African data precludes a detailed spatial analysis, the overall signals of activity from North Africa and the European central Mediterranean share many characteristics. In particular, the Early Neolithic lull at 5100 cal. BC is common to both continents, although the fluctuations in activity that followed over the subsequent millennia were rather different. As discussed by Manning and Timpson (2014), such trends in the combination of archaeological data over a huge area suggest that human activity in prehistory was strongly influenced by climatic forces, even though the human response to these environmental challenges was different in each region and time period.

The mid fourth millennium BC is associated with the start of the Copper Age in the central Mediterranean, which brought with it marked regional diversity in the archaeological record, particularly in the island contexts of Sicily, Sardinia and the Maltese archipelago—as illustrated in the density models (Fig. 4, point ‘D’). Peninsular Italian Copper Age groups show genetic continuity from the Neolithic, in contrast to later Bronze Age groups (D’Amore et al., 2010a, 2010b; Saupe et al., 2021), indicating apparent population stability during the period. In central Italy, a gradual increase in activity occurred from 3800 cal. BC, peaking at 3500 cal. BC. Settlement evidence for the central Italian Copper Age is fairly patchy, although the occurrence of densely clustered cemeteries in areas lacking definitive settlement evidence (e.g. the Tuscany–Latium border), as well as a growing body of stable settlement evidence in areas of Marche and central Latium (Anzidei & Carboni, 2020; Cazzella, & Moscoloni, 1999; Manfredini, 2014) paints a picture of population increase during the earlier Copper Age in this region of Italy, and seems to be reflected in the KDE model. These results are similar to those reported for the fourth millennium BC by Palmisano et al., (2017, 2018); however, in discussing their results they incorrectly state the beginning of the Copper Age in central Italy as 3000 cal. BC, when it is widely acknowledged as starting at approximately 3600 cal. BC (Dolfini, 2010, 2013; Cocchi Genick, 2013). Thus, the discussion by Palmisano et al. (2017, 2018) of trends across the fourth millennium BC is not framed within the appropriate cultural context, underscoring the importance of acknowledging local chronologies within larger syntheses so that they remain relevant to the traditions of research in the region.

In contrast to central Italy, activity in southern Italy remained low, reflecting the scarce evidence for Copper Age settlement in regions such as Apulia, and only a slight rise can be observed for northern Italy. In Sicily, a significant upturn in activity at 4000 cal. BC corresponds to the beginning of the ‘proto-Eneolithic’, where an increase in the number of archaeological sites is associated with the San Cono–Piano Notaro and Conca d’Oro cultures. Unlike on the mainland, in Sicily the peak steadily decreased throughout the first half of the fourth millennium BC (Fig. 4, point ‘D’). By this time, activity in the Maltese Islands underwent a significant increase, with growth rates above 2% per annum, from 3800 cal. BC until a peak at 3400 cal. BC. This is associated with the Żebbuġ and Ġgantija phases, which saw the development of megalithic architecture, which proliferated throughout the ‘Temple Period’ then briefly declined during the transition to the third millennium BC. The close parallels between Sicilian San Cono–Piano Notaro and Maltese Żebbuġ material culture (Leighton, 1999, p. 93; Speciale, 2011), and evidence for direct exchange of material culture (Barone et al., 2010), clearly demonstrate contact between the two islands at a time of fluctuating activity levels. While we should be cautious about stretching our interpretations of the data too far, the sustained phase of growth in the activity model for the Maltese Islands could be interpreted as a response to demographic pressures in Sicily, and may reaffirm that the unique ‘Temple Period’ cultures of Malta and Gozo had an antecedent in Sicily around 4000 cal. BC.

In Sardinia and southeast France, significant peaks occurred early in the fourth millennium BC. These points represent relatively short-term flares of activity and only in northern Italy does a modest mid-fourth-millennium BC increase appear more sustained, as it was during the Neolithic. The fourth millennium BC in the central Mediterranean shows asynchronous developments in anthropogenic activity, most of which occur in what are Late/Final Neolithic cultural contexts (Sardinia, Sicily, SE France, Maltese Islands) rather than in the Copper Age as in central Italy. This not only highlights the gradual nature of the transformations from the Neolithic and Copper Age in the central Mediterranean, but also suggests that the driving features of these trends were probably the social and economic developments that characterize the fourth millennium BC, rather than the impact of technological developments related to metal working and resource exploitation.

Whilst the density models suggest lower but stable levels of human activity across much of the central Mediterranean in the third millennium BC, there is a distinctive apogee in the KDE models at 2500 cal. BC in the Maltese Islands (Fig. 4, point ‘E’; see also Fig. 10). The mid-third-millennium BC peak followed a downturn around 3000 cal. BC, and possibly reflects a period of population recovery and eventual flourishing of ritual activity on the islands after an apparently difficult few centuries. Current evidence indicates that the soil cover of the Maltese Islands became progressively denuded over the course of the Temple Period, and that soil amendment processes were undertaken possibly as early as the early–mid third millennium BC (French et al., 2018). This may suggest that land management practices played a part in averting total collapse of the Temple Period around 3000 cal. BC, and instead triggered a rebound. It has long been suggested that agriculture intensified towards the end of the Temple Period, during the concluding Tarxien phase, under a more controlled system for which megalithic sites formed a focus, and possibly in response to increasing economic and environmental instability (Stoddart et al., 1993; Trump, 1980). Recent work has significantly added to this picture by arguing that the Maltese megalithic sites played an important economic role in facilitating the display, consumption and organisation of resources within the restricted environment of the islands (Barratt et al., 2020; Malone et al., 2020b, p. 477). Archaeological evidence from excavated sites shows evidence for increased ritual activity at 2500 cal. BC (McLaughlin et al., 2020a; Thompson et al., 2020), and whilst the phasing of the Maltese temples remains difficult (Grima, 2008), it has been suggested that the present form of most megalithic sites on the islands reflects a final episode of restructuring and ritual elaboration at a crucial point towards the end of the Temple Period (Malone, 2007). Episodes of crisis management have been noted in monument-building societies elsewhere, as in the Sardinian Bronze Age (Ialongo, 2018), although in the case of the Maltese Islands the recovery was short lived. Activity on the islands appears to have tipped into decline after 2500 cal. BC, during a period that is associated with declining population health, the eventual end of monument building and significant environmental change driven by increasing aridity (French et al., 2020, p. 320).

This localized trend embodies the singularity of the Maltese archipelago’s archaeological course during the fourth and third millennia BC. Elsewhere in the central Mediterranean, it is only on neighbouring Sicily that a significant increase in activity is initiated at around 2800 cal. BC (Fig. 4, point ‘F’; Fig. 10), as part of a gradual intensification leading into the Early Bronze Age (see following section for discussion). Whilst the gradual growth in Sicily seems somewhat concurrent with the decline on the Maltese Islands at 2500 cal. BC, the growth in Sicily is initiated some three hundred years earlier. It has been proposed that the end of the Maltese Temple Period prompted an exodus out of the islands into neighbouring areas, most likely Sicily (Bonanno, 1993), and archaeological evidence points towards increasing ties between the two regions in the later third millennium BC (Procelli, 1996; Leighton, 1999, p. 137; Tanasi, 2014). The results of the KDE, therefore, do not appear to support this directly, and recent research has instead shown that the end of the Maltese Temple Period was defined by a gradual transition into the Early Bronze Age with a transitional ‘Thermi’ ware phase in the mid–late third millennium BC (McLaughlin et al., 2020a, p. 33).

The decline in activity levels at the close of the third millennium BC in the Maltese Islands is also mirrored by the KDE models from southern Italy and Mediterranean Africa (Fig. 10). As the Early Bronze Age emerged, only in southeast France, northern Italy, and Sicily was a significant increase in activity observed (Fig. 4, point ‘F’). Northern Italy enjoyed stability during the first half of the second millennium BC, in contrast to the adjacent areas of southeast France and central Italy, where a pronounced drop in activity appears to have occurred (Fig. 4, point ‘G’). In Sicily, this pattern is also apparent, as the end of the Copper Age and Early Bronze Age signalled a 500-year period of sustained growth that reached its peak at 2000 cal BC (Fig. 4, point ‘F’), followed by a significant decrease in activity around 1700 cal. BC in the lead-up to the Middle Bronze Age (Fig. 4, point ‘G’).

The Early Bronze Age of Sicily is traditionally recognized as a period of considerable settlement expansion and population increase (Malone et al., 1994a, 1994b), but Leighton (2005) has argued that a lack of landscape survey data for Sicily may mean that this narrative has been historically overemphasized (Leighton, 2005). The density models seem to support the former interpretation, although understanding the decline around 1700 cal. BC is more problematic. Leighton (2005) further suggested that contraction and discontinuity in settlement patterns occurred between the Early and Middle Bronze Ages in Sicily, whilst the Aeolian Islands show similar contraction of settlement into nucleated villages located on naturally defended higher ground as the Early Bronze Age progressed (Alberti, 2013a; Bietti Sestieri, 2013b). In central Sicily, site counts also suggest a sharp increase in Late Copper Age and Early Bronze Age settlement, followed by a considerable drop in the Middle Bronze Age (Giannitrapani, 2016), mirroring the trends in our density model. The results of the KDE analysis (Fig. 4, point ‘G’) may therefore corroborate the evidence for settlement nucleation and a punctuated transition between the Sicilian Early and Middle Bronze Ages—although the decline observed at 1700 cal. BC does appear to have been a synchronous phenomenon across the wider central Mediterranean. Interestingly, the dynamics of human activity in Sicily, as suggested by the KDE and observed in the archaeological record, also appear to correspond loosely with episodes of demographic change on the island, namely the arrival of Steppe ancestry by 2200 cal BC and possible Aegean ancestry between 1800 and 1500 cal. BC (Fernandes et al., 2020).

The density models and animated map are particularly illustrative of events in Early and Middle Bronze Age northern Italy, where the radiocarbon dates derive largely from Polada pile dwellings along the southern fringe of the Alps, and the Terramare system on the central Po Plain. The rapid demographic development and settlement density that is associated with the Polada culture (Barfield, 1994a; Nicolis, 2013) is clearly reflected in the KDE models (Fig. 4, point ‘F’) and the subsequent rise of the Terramare system sees further development of this trend. The demographic increase associated with the Terramare was accompanied by a general increase in site size over time (Cardarelli, 2009; Vanzetti, 2013), with the largest sites estimated to have accommodated up to a thousand people (Nicolis, 2013), and with population estimates for the entire system as high as 150,000 people (Cardarelli, 2018). With the exception of an insignificant decrease around 1700 cal. BC, the density models show consistent activity levels between the Early and Middle Bronze Age in northern Italy. This trend is unsurprising, given that both periods are associated with increased population levels, with the major change across the Early Bronze Age–Middle Bronze Age transition being a marked spatial shift in settlement from the southern fringe of the Alps to the Po Plain. The shift towards extremely high settlement density on the Po Plain and continuing demographic expansion is therefore better visualized in the animated radiocarbon maps from 2200 to 1450 cal. BC (Fig. 5; see supplementary data). The consistency in the KDE models does, however, indicate some degree of continuity between the two periods, and may in some way contribute to the remaining debate as to whether the Terramare developed out of the earlier Polada pile dwellings (Nicolis, 2013; Vanzetti, 2013).

At the end of the Terramare, the gradual decline documented in the density models spanning approximately 1500 and 1100 cal. BC (approximately 0.9% per annum) does not reflect the collapse that is traditionally associated with the north Italian Recent Bronze Age between 1350 and 1150 BC (Cardarelli, 2009; Vanzetti, 2013). Whilst Terramare sites suffered decline in the southern Po Plain towards the end of the second millennium BC, several well-studied larger villages in the Grandi Valli Veronesi north of the Po River continued to thrive into the Final Bronze Age (Cupitò et al., 2015), and were engaged in broader continental and eastern Mediterranean trade networks as well as a high degree of intergroup mobility between settlements (Cavazutti et al., 2019). However, it is still a matter of debate whether the sites were suddenly abandoned at exactly the same time throughout the territory or whether the abandonment occurred over a prolonged period of crisis (Cardarelli, 2009, p. 485). Whilst the KDE models reflect the general timing of the Terramare collapse, the precise dynamics of the Recent and Final Bronze Age in northern Italy are perhaps better visualised in the animated maps where the activity associated with the Grandi Valli Veronesi sites is apparent (see supplementary data).

The results of the KDE models from 1100 cal. BC, following the decline of the Terramare, reflect the reduced levels of human activity on the Po Plain during the Final Bronze Age and Early Iron Age (Barfield, 1994a), in comparison with neighbouring areas of southeast France and central Italy which saw sustained and gradual growth (Fig. 4) (cf. Mathers and Stoddart, 1994 who registered these unaligned cycles of expansion and decline). The extent to which this trend may relate to demographic shifts is difficult to assess and touches upon a controversial theme that dominated research on the Terramare until the mid twentieth century (see Pearce, 1998). However, this period in southeast France is associated with north Italian influences on material culture (Mordant, 2013), also seen to a lesser extent in central Italy (Cardarelli, 2009; Manfredini et al., 2009). By contrast, southern Italy remained very quiet at this time, as reflected in the archaeological record (Bietti Sestieri, 2013a), but the impact of negative research bias must be emphasized, as the south of the Italian peninsula has on the whole fewer dated sites to represent later periods.

A significant and rather sudden decline in the KDE models occurs in central Italy, Corsica and Sardinia in the early first millennium BC (Fig. 4, point ‘H’). This is most pronounced in the record from Sardinia associated with the end of the Nuragic civilization. From 1500 cal. BC activity on the island gradually increased year-on-year, reaching its most intense level at a point between 980 and 820 BC, which was apparently succeeded by sudden collapse. Using simulation and back-calibration we have modelled different scenarios for this process (Fig. 9, see Supporting Information pp. 18–20); the models most consistent with the data feature an abrupt drop in activity around 800 cal. BC (Fig. 9, simulations 1 and 2). Although it is important to acknowledge that this approach does not ‘prove’ the mathematical correctness of the model, it nonetheless provides a plausible explanation for patterning of the radiocarbon data. The density models suggest that there was between a four- and 13-fold reduction in activity in Sardinia over a 150–175 year period, beginning between 980 and 820 BC. Whilst these results could reflect an edge effect as a result of negative research biases, clear regional differences across Sardinia during the Final Bronze Age (Lo Schiavo, 2013), and the apparent weakening and restructuring of the political structure of Nuragic civilization in the face of increasing foreign contact (Blake, 2015), are important factors that led to the decline of the nuraghi at the onset of the Iron Age. The first millennium BC in Sardinia also appears to signal a period of significant genomic transformation on the island (Marcus et al., 2020), with post-Nuragic period Iron Age individuals showing less evidence for pre-Bronze Age indigenous ancestry (Fernandes et al., 2020), altering the previously-held view that Sardinia was isolated from substantial genetic admixture and population migrations since the Neolithic (see Chang et al., 2018 for overview).

The same period in central Italy saw a similar, but less dramatic, reduction, which by virtue of a better-resolved record, can be more precisely dated to between 900 and 820 BC. In central Italy, the decline was a two- to three-fold reduction over the course of about 175 years. Significantly, in central Italy the reduction in activity recovered and by 600 cal. BC activity was once again intensifying, now associated with the emergence of city states (Barker & Stoddart, 1994). It will be important to concentrate research and future dating projects on this period between 900 and 600 BC, in conjunction with use of Bayesian statistics on relevant stratigraphies at the beginning of the Hallstatt plateau to investigate this significant phase of central Italian state formation and whether nucleation was accompanied by demographic pressures. Some important stratigraphies in the powerful places of Etruria cross this boundary (e.g. Tarquinia) and could be employed to test alternative interpretations and the validity of the demographic changes. In Sardinia, however, the recovery never came following the endemic collapse of 900 cal. BC (Fig. 4, point H), after which settlement and burial activity declined (Tronchetti, 2015), with most Nuragic sites abandoned and the nuraghe itself being reduced to an almost totemic symbol of Sardinian identity (Blake, 1997; Minoja and Usai, 2015).

The question of whether this decline was sudden or gradual is therefore an important one. Although radiocarbon data are not well suited to reflecting rapid change due to the uncertainties involved, simulation modelling can be used to build hypothetical models of activity, and via a stochastic ‘Monte Carlo’ process, calculate how this pattern would be reflected in archaeological radiocarbon data. Such exercises also exclude the possibility that plateaux in the calibration curve influence the kernel density estimates. Testing three alternative scenarios in this way (Fig. 11), we can see that the Nuragic decline more closely corresponds to a sudden and drastic reduction in activity, rather than a gradual one.

It is possible to draw further parallels between the significant trends of central Italy, Sardinia and Corsica with events occurring elsewhere, using data from the RADON-B database. The downturn of 900–820 BC seen in the radiocarbon record from central Italy is mirrored, somewhat surprisingly, by events much further north in Scandinavia and Ireland (Fig. 12). In all three cases the density model plummets to lower values that are then sustained from c. 700 cal. BC. The pattern is also weakly represented by perturbations in the activity models from southern Italy, France and Britain. Switzerland experiences decline at this point, but no recovery from 700 cal. BC; instead the falling activity levels are sustained into the Iron Age. In Iberia, a similar pattern of intensification and subsequent decline also occurred, although slightly earlier than elsewhere. In their wider European context, Sardinia and Corsica present cases that mirror the rapid downturn seen in central Italy, Scandinavia and Ireland, but the timing of the collapse in the Mediterranean seems slightly earlier. The hypothetical model of drastic decline presented in Fig. 11 is consistent with real archaeological data from a great variety of locations and together they indicate a major mid-ninth-century BC event that impacted human activity across Europe. In some regions this manifests as a decline, in others as an apparent collapse. If real, this is a pattern that must have had a major bearing on the many cultural transitions that were occurring during this period, for example by causing abandonment of some localities and nucleation in others. In the case of central Italy, the period c. 950–800 BC was a period of centralisation into fewer settlements and our data are compatible with multiple ways of modelling this process. Nucleation may have been a response to demographic decline, and a collective solution to the problem of weakening social connections in an otherwise more dispersed settlement system. Alternatively, it may simply reflect a situation where fewer sites are represented by fewer dates. Our resolution of these processes is obviously hampered by the fact that there have been fewer attempts to apply radiocarbon dating to Iron Age, Phoenician and Classical contexts, and the subsequent ‘Hallstatt’ plateau in the calibration curve. We, however, contend that the pattern observed here for the early first millennium BC is broadly valid, given its occurrence in certain independent and extremely well-resolved radiocarbon datasets (such as Ireland, which is unaffected by such research biases), and highlights both an urgent need to undertake assessments of alternative proxies for activity (such as frequency of pottery finds), and the utility of extending studies of prehistoric demography beyond their usual 750 BC cut-off date.