The archaeological region of Bòbila Madurell (Sant Quirze del Vallès)-Can Gambús (Sabadell), where the Cova del Frare site is located, is the paradigmatic reference of the coastal or Vallesià group, with pit burials and a large number and wide variety of allochthonous finds19. The 49 radiocarbon dates published to date confirm that both sectors belonged to a single cemetery occupied between 4100 − 4015 cal BC and 3655 − 3560 cal BC, although the Bòbila Madurell sector (4130 − 4010/3765 − 3615 cal BC) began shortly before the Can Gambús sector (4115 − 3980/3640 − 3490 cal BC)30,31,35.
In contrast, the group of stone slab tombs from inland Catalonia (Solsonià facies) is situated between 4000 and 3500 cal BC with a maximum and significant concentration of probability intervals between 3800 and 3600 cal BC (26 dates)47 and has less allochthonous material48.
Studies of the available radiocarbon dates estimate a chronology for the Late Neolithic of around 3435 − 3110/2595 − 2320 cal BC35. They suggest a period of overlap between the first collective burials in the Late Neolithic and the last stone tombs of inland Catalonia between 3490 − 3215 and 3360 − 3120 cal BC47. New dates show a beginning of the Late Neolithic from 3600 − 3500 cal BC39.
In this paper we presented the find of a Baltic amber bead in a context dated to the Late Neolithic (3634 − 3370 cal BC). Although the use of amber in early contexts on the Iberian Peninsula is not unusual, the fact that it originated in northern Europe is completely exceptional.
In the Iberian Peninsula there are more than 160 locations with palaeontological amber outcrops49,50 (Fig. 1). Most of these amber deposits are Albian in age (Early Cretaceous) and only a few localities in Asturias and Catalonia date from the Late Cretaceous. Likewise, only two localities with amber from the Late Triassic Period are known, both in Alicante.
In general, the amber deposits are distributed in a strip that runs from the east to the north of the Iberian Peninsula, broadly corresponding to the coastline during the Early Cretaceous. Specifically, at a distance of about 50 km from the Cova del Frare there are various amber deposits, initially thought to be fossil amber from the conglomerates of the Sant Llorenç del Munt mountain (Fig. 1).
The amber outcrops in Catalonia are found in the Maastrichtian (into the Garumnian facies) associated with lignite deposits that have been exploited until recent times in the Pre-Pyrenees (mainly in the Figols-Vilada area and at Isona in the Tremp Basin). Amber usually appears in small amounts as tiny drops in the greyish muddy layers and occasionally as masses up to several centimetres. No bioinclusions have been found in the samples recovered50,51.
The main amber deposits –larger than those of Catalonia– are documented in the Central Asturian Depression (CAD), the Basque-Cantabrian Basin (BC) and the Maestrat Basin (MB), with well-known palaeontological amber deposits such as those of El Soplao or San Just, where specimens weighing about 1 kg have been found52,53. These Iberian deposits were exploited by prehistoric communities from the Upper Palaeolithic on. The earliest archaeological pieces analysed are the Aurignacian, Gravettian and Magdalenian fragments found in caves, some of which have evident anthropogenic marks54,55. These local resources continued to be used during the second half of the fourth and the first half of the third millennia BC in megalithic monuments in which Bell Beaker finds were also documented54,56. The most recent context in which the exploitation of local amber has been documented is the megalithic complex of Los Lagos I (Cantabria), where the remains of amber were found in the chamber. This assemblage provided a date of UGRA575, 3270 ± 70 BP, 1731 − 1404 cal BC 2σ57 (Fig. 9).
Baltic amber is currently believed to have arrived at the Iberian Peninsula much later. In the megalithic monument of Larrarte (Guipúzkoa), an amber bead was documented among predominantly Chalcolithic grave goods, with abundant stone tools, sherds of Bell Beaker and plain pottery, and discoidal lignite and stone beads58. Unfortunately, none of the twelve buried individuals could be dated, due to a lack of collagen, and the only dates for the dolmen analysed by the Teledyne Isotopes laboratories (5810 ± 290 BP and 5070 ± 140 BP) come from two pieces of charcoal collected outside the chamber, in the mound, with the inherent problems of “old wood” and the uncertainty derived from the lack of contextual association. A safer instance is the context of the Baltic amber bead found in Burial 38 at La Almoloya (Murcia), a double burial in pithos of exceptional opulence59. The male individual, 35–40 years old, is associated with a small amber bead of Baltic origin, not only the sole evidence of amber in the entire Argaric area, but also the first evidence of the arrival of Baltic amber with a definite context. The individual provided a date of 3354 ± 33 BP (1738 − 1534 cal BC).
With the exception of these two pieces, the amber beads of Baltic origin are concentrated in the northeast of the Iberian Peninsula. In this area there are seven archaeological sites with analysed pieces of Baltic origin (Fig. 9). These are the beads from Cabana del Moro de Colomera, Pedra Cabana, El Bosc, La Pera, El Garrofet, Muricecs, and Fosa del Gegant. However, most of these contexts are collective burials excavated in the early 20th century for which we do not have detailed stratigraphic or contextual information, and it is not possible to associate pieces with particular individuals. However, given the associated archaeological finds (ranging from Bell Beaker items to bronze objects with between 10 and 12% Sn and even iron or vitreous paste beads), all these cases can be considered as later than the Cova del Frare.
Against this background, the Late Neolithic (3634 − 3363 2σ cal BC) collective burial phase of the Cova del Frare provides the earliest evidence of Baltic amber in Western Europe. In the case of the northeastern Peninsula, Baltic amber use lasted throughout the Chalcolithic and Bronze Age without penetrating interior or southern Iberia until later, during the Late Bronze/First Iron Age (with the exception of the aforementioned La Almoloya bead dated to the middle of the 2nd millennium BC). Even though being just a single bead, this finding places the occurrence of Baltic amber in Western Europe more than a millennium earlier than previously thought. Crucially, it also compels us to question the traditionally assumed link between Baltic amber and the spread of Bell Beaker culture during the 3rd Millennium BC60.
In northern Europe, where Baltic amber occurs naturally, this raw material had been used since the Palaeolithic and Mesolithic periods, although it was during the Neolithic (4000 − 3200 BC) and up to the 3rd millennium BC that its exploitation increased considerably. At that time amber was distributed throughout the area in which the Funnel Beaker Culture (FBC) developed, spanning present-day Denmark, the Netherlands and the north of present-day Germany and Poland. It was used to make buttons with V-shaped perforations, discs, beads, pendants and some figures or beads shaped like battle axes, demonstrating the importance of the axe as symbol60.
Amber was worked in large quantities from the Neolithic on (with more than 50,000 Neolithic amber beads documented). Thus, large deposits with amber objects have been found, such as that documented at Sortekærs Mose. Some of these deposits came to contain more than 8 kg of amber, evidencing the intense exploitation of this local raw material, which was easily accessible on the coast in the Neolithic period.
During the 3rd millennium BC, some Baltic amber beads began to appear in other European regions. Du Gardin34 began to document pieces of amber from between 3000 − 2600 BC at ten French sites (Villevenard, Oyes, Charavines, Annecy, Epone, Flavacourt, Méréaucourt, Mériel, Chouilly and Ay Champagne); of those analysed, one bead from Oyes, another from Charavines and five from Layers 4 and 5 at Méréaucourt were found to be Baltic succinite. Before this paper, these constituted the earliest evidence of Baltic amber in Western Europe, despite France having local amber resources34,61. Nevertheless, there is evidence of the exploitation of local resources in earlier and later times. Like in Iberia, the earliest amber ornaments in France date to the Palaeolithic. At Isturitz, 27 pieces of amber with working marks have been documented, including two pierced earrings62 made with local resources63. The earliest amber objects documented so far in Italy date back to the end of the 4th millennium BC11 although the use of local amber (simetite) is proposed for these early objects. The earliest evidence of the arrival of Baltic amber to Italy dates to 1800 cal BC12,64.
Between 2600 and 2200 BC, there are 21 French sites were amber is found. The analysed beads –two from Thiré, two from Narbonne, one from Xanton-Chassenon and another from Montagnac-Montpezat– revealed a Baltic origin34, while two from Narbonne remain unidentified. Unfortunately Du Gardin does not publish the spectra analysed, so we cannot compare them with other sources of amber. At this time amber also appears at the archaeological sites in the south of France closest to the Iberian Peninsula, such as Salses, Saint-Pargoire, Saint Maurice-de-Navacelles, Châteaurenard, Montpezat or Narbonne (Fig. 9). In fact, this area has the greatest concentration of amber pieces in France, with another small group in Brittany, in the Parisian basin, following the course of the River Seine, or in the Lyon area, following the course of the River Rhône. It is also significant that, as in the Iberian Peninsula, the use of amber decreased considerably with the dawn of the Bronze Age. Between 2200 and 1800 BC, amber has only been documented at five French archaeological sites, although this increases to 19 in a second phase between 1800 and 1400 BC.
We can relate this situation to the close links between the northeast of the Iberian Peninsula and the south of France beginning in the Neolithic26,65−67. Evidence for this includes the presence of Barremian-Bedoulian flint from the Vaucluse region in northeastern Iberia, as well as other exogenous materials, such as Sardinian obsidian and Alpine rocks23,26,68. These connections, which become especially evident with the Vérasan group and other Late Neolithic-Chalcolithic groups who shared similar material culture, continued until at least the late 3rd millennium BC69. The Pyrenees mountains are currently seen as a barrier constituting the dividing line between two countries. During prehistory, however, they were far from being perceived as a border, but rather as a zone of contact and interaction for social groups from at least the Early Neolithic. This became very evident in the Middle Neolithic and especially in the Late Neolithic and Chalcolithic Vérasan, a group that twinned the populations on both sides of the range39.
Recent studies suggest that not all the finds in the Iberian northeast came from the same trading network, but rather from different networks resulting from contacts with various communities with a relatively distinct temporal validity21,23,30. In any case, the amount of exogenous materials involved in these networks in which amber seem to have participated only occasionally, would have begun to decrease from 3655 − 3550 cal BC, suggesting the beginning of what may have been a sudden collapse of the entire network. These dates appear to coincide with profound changes in funerary practices in terms of structures, burial methods and grave goods. From that moment on, collective burials in different places –especially dolmens, hypogea and caves– succeeded previous practices31,35.