The introduction of megalithic grave types
The results confirm that the dolmens and passage graves were used at the same time and support the hypotheses of Persson and Sjögren about the construction time of these graves (Persson and Sjögren 1995; Sjögren 2003, 2011), although the introduction of both dolmens and passage graves can probably be pushed back to 3500 to 3400 cal BC, which agrees with the Bayesian models of megalithic graves (Figs. A5–7). The first burials of passage graves are also consistent with the dates of the bark samples from Danish passage graves (Dehn and Illum Hansen 2006). In eight passage graves, bark samples were dated to the transition between EN and MN with one single date placed in the ENII (Dehn and Illum Hansen 2006). However, considering the distribution and proportion of the early dates (Figs. 8 and 9; Table A1), a slightly earlier introduction of the dolmens is suggested (Figs. A5–7). Similar results, but with a later start of the passage graves, were presented in a study from the Flintbek cemetery in northern Germany, where the dolmens were dated to 3600 to 3350 cal BC and the passage graves to 3350 to 3100 cal BC (Furholt and Mischka 2018).
The unexpected EN/MN human remains recovered from some of the gallery graves have consequences for how we understand the succession and use of megalithic graves. Therefore, more thorough investigations are required. A few hypotheses are here suggested to explain the early dates:
The early skeleton remains originate from reburial of relics (bones with special meanings, kept or circulated for specific purposes) or bones from earlier graves.
These graves are misinterpreted dolmens.
Some of the gallery graves are reconstructed graves of earlier types.
Some of the gallery graves were actually constructed parallel to the dolmens and passage graves.
The megalith types are not valid and shapes were more varied than previously thought.
The scenarios are tested by comparing the 14C dates with various characteristics of the gallery graves and by detailed discussions of the samples and grave constructions. Furthermore, the results are related to ethnographical examples and previous Neolithic and early Bronze Age research. Thereafter, the megalithic grave construction of Västergötland is discussed, and lastly, regional similarities and differences are addressed.
Old bones or early graves?
Ethnological examples have revealed that megalithic graves have been used in societies with different social organizations and ideological beliefs, sometimes involving complex burial practices in many steps extending over several years, including recovery of relics in and moving skeletal remains between graves (Bloch 1992, 1994; Hutton 1921; Jamir 2004; Jeunesse and Denaire 2018; Parker Pearson and Regnier 2018; Wunderlich 2019). Some observations are of particular interest concerning the handling of bones and the presence of older bones in the megalithic tombs. In Sumba, Indonesia, remains from individual graves can be moved to the collective clan dolmens 10 to 20 years after the primary burial (Jeunesse and Denaire 2018). Bloch (1988: 13) has described how the Merina on Madagascar exhume and rebury their deceased after some years in the megalithic graves. The intricate reasons for certain practices vary within and between different societies. Placing and moving of skeletons and bones can, for example, be determined by regulations concerning incest (Jeunesse and Denaire 2018). Among the Merina, the empty grave is considered dangerous and therefore bones from graves of former ancestors must be put in the grave before it can be used for new burials as one cannot be alone in the grave (Bloch 1982: 213).
Practices of recovering and moving of bones can thus be attested in ethnological examples and could have also been occurring in prehistory. However, these multifaceted burial traditions are often difficult to detect in the archaeological record. This means that burials that look very similar from an archaeological perspective can in fact be very different. The skeletal assemblages of often commingled bones in the megalithic graves are difficult to interpret. The manipulation of human remains, such as relics and bones being moved and taken out of graves as well as the circulation of human remains, have been suggested during the European Neolithic and Bronze Age (Brozio 2016; Fowler 2010; Parker Pearson et al. 2005, 2007; Richards 1988; Thomas 1998). A missing femur of a woman buried in an EN flat grave at Oldenburg-Dannau, Germany, was interpreted as deliberately removed and placed in a nearby well (Brozio 2016).
The placement of remnants of ancestors might have been a practice when a new grave was constructed or when people first established themselves in a new area. Bones from older graves placed in new graves could have been a strategy of claiming a connection to former groups in a certain area. A similar interpretation of the extensive reuse of passage graves during the LN is possible. Some possible ways of identifying re-deposition are as follows: only crania or large bones have early dates, special placements of the early bones or a low number of early dates compared with the remaining burials. Furthermore, re-deposition of old human remains can most likely be excluded if accompanied by early artefacts and/or animal bones.
Considering the bone elements, small bones are in most cases absent as most of the graves were excavated at a time when the skeletal remains were neglected, with the exception of intact skulls. Of the EN/MN dates in gallery graves, nine samples derive from skulls (eight teeth and one cranium fragment) and five from arm bones (two radius and three humerus) (Appendix 1). The sampled individuals from single roomed graves derive from both cranial and postcranial elements. Both dates from multi roomed gallery graves derive from teeth. Hence, no conclusion can be drawn, as no small bones were available for dating.
In several cases, some kind of stratigraphy occurs in the megalithic graves with bones separated in different layers or horizontal division where older bones have been pushed aside. In the latter case, the oldest bones are expected to be found closer to the walls or in the back of the chamber. In several megalithic graves, the latest burial was found more or less intact compared with the older and more fragmented skeletons. Possible foundation depositions were observed in two passage graves (Ramshögen and Carlshögen) in Scania (Strömberg 1971a). However, these bones have not been dated. If an older bone was placed in the grave in an initial phase, then the location of the relic would not necessarily differ from the primary burials, if not a special/deviating location was chosen. However, if the older bone was placed in the grave at a later stage, then the bone would be found in a more unexpected stratigraphy.
In the single roomed graves, the bones were found in the chambers and in Utbogården gallery grave the MN bone derived from an adult individual found in the main chamber along with the majority of bones (Appendix 1, 2). The exact placement of the early bones are unknown. No special deposits in the studied graves could be observed, but due to the poor documentation of the bones, no conclusion can be drawn.
Considering the frequency of early dates in the multi-roomed gallery graves, the deliberate placement of old bones remains a possibility. Only one single individual was dated to the EN/MN or MN in each of the two multi roomed gallery graves with port-holes in Västergötland, while the rest were dated to LN and EBA (1/3 and 1/10). The single roomed graves with MN dates on the other hand do not contain any LN dates. Only single dates were achieved from two of them (Table 2; Appendix 2). The two remaining single roomed graves contained several individuals dated to the MN and the bones derived from individuals of different ages and of both sexes. It is thus likely that the open single roomed gallery graves with MN dates are indeed early graves, while the multi-roomed graves might contain relics.
If the low frequency of early dates in certain gallery graves is an argument for reburial of old bones, this can likewise be applied to passage graves and dolmens containing single EN dates. However, the older bones are expected to be more fragmented and less preserved in graves of successive burials and the possible practice of cleaning out earlier burials might also affect the low frequency of bones from the earliest burial phase. At Rössberga, two megalithic graves were placed only a few meters apart: a passage grave with a 9 × 2 m large chamber and an 8-meter-long passage surrounded by a cairn, and a 3.5 × 1 m large gallery grave covered by a low cairn (Appendix 2). In the passage grave, one of 24 sampled individuals showed an ENII date, while the rest of the burials were dated to the MN. The single tooth sampled from the nearby gallery grave displayed a date very similar to the earliest date in the passage grave (Appendix 1). The two graves might be contemporaneous and meant for two different categories of people/dead. A scenario when an older skeleton/skull was brought from the older gallery grave and deposited in the MN passage grave is also possible. Likewise, the nearby gallery grave might have served as a secondary grave where the remains of older burials from the passage grave were placed, which could explain the single ENII date.
Clearing out of megalithic graves has been discussed in several regions, both in passage and gallery graves (Blank 2016: 53; Chambon 2003; Hansen 1924; Persson and Sjögren 2001: 46; Strömberg 1971b). No examples of cleared out passage graves can be verified, but new floors were sometimes constructed to separate the new burials from the previous ones (Hommerberg 1944; Strömberg 1971b). A pit next to the gallery grave in Annelund with unburnt human bone and some artefacts have been interpreted as burials cleared out from the gallery grave (Andersson and Hjärthner-Holdar 1989: 211; Appendix 2). Cleared out gallery graves could explain the low number of MN dates recovered especially in multi-roomed gallery graves. However, the fact that the multi-roomed gallery graves with early dates show an extensive use in the LN and EBA compared with the dolmens and passage graves is more difficult to explain.
MN artefacts and animal bones are other arguments that support the assumption of early graves. As mentioned above, MN use of most of the gallery graves with MN 14C dates can be confirmed by MN artefacts, and two additional gallery graves with ante-chambers as well as an open single roomed gallery grave contained MN artefacts (Table 2). Furthermore, a multi-roomed gallery grave with a port-hole, Måns-Nilsgården gallery grave, contained a sheep/goat bone dated to the MNA and no traces of nearby settlements were observed (Table 2; Appendix 2).
The gallery graves outside of the sedimentary areas in western Sweden are difficult to date, due to the poor bone preservation. It is problematic to date megalithic graves in general as many of the graves have been exposed to later use and looting. However, there are several known MN finds from gallery graves in southwestern Sweden. In Table A3, a compilation of known MN finds from graves classified as gallery graves is presented. The finds might be depositions from earlier graves, although other explanations are also possible. Flakes or pieces of polished flint axes are rather common finds in gallery graves, especially in areas where raw flint is uncommon. The fragmented MN axes can therefore be explained by reuse of older artefacts. According to Apel (2001: 13), thick-butted flint axes were used into the LNI. The occurrence of MN artefacts such as tanged flint arrowheads and MN pottery could be a result of local continuation of certain craft traditions. The MN finds might also have been deposited in the graves during the LN and possessed a certain symbolic value. In some cases, the finds could originate from earlier settlements or graves, accidentally being part of the grave filling, although in the examples presented in Table A3 this is not likely.
In Table A3, twenty gallery graves of different size contained EN/MN finds. In the case of Björkön, numerous PWC pottery sherds and some flints were found in front of the entrance. This can be compared with the common practice of entrance deposition at passage graves. In addition to the finds in the table, polished thick-butted flint axes occur in other regions such as Halland (Hyltegården gallery grave, Förlanda parish and Hassungared gallery grave, Lindome parish) and a thick-butted stone axe is known from Källås gallery grave, Gillberga parish in Värmland. The early artefacts in these graves, at least in some of them, are likely to indicate when the graves were used.
Consequently, this opens up for a wider distribution of MN megalithic graves to areas between the coast and Falbygden and might also connect Falbygden with other known MN megalithic areas such as the west coast. Sjögren (2003: 81) has pointed out that some of the gallery graves in southwestern Sweden might be wrongly classified dolmens. Whether the early graves are dolmens and/or gallery grave is discussed below.
Another possibility which might explain older bones as well as older finds is that these gallery graves were rebuilt dolmens or passage graves or that they were constructed on top of demolished early megalithic graves. This would leave traces of removed slabs and older burial layers or entrance deposits. There are no indications of this in the documentation of the concerned graves and this is therefore considered unlikely. However, there are several examples of passage graves which have been modified and rebuilt in various ways during the LN (Blank 2017; Hommerberg 1944; Sjögren 2003; Strömberg 1971b).
A similar possibility is that some of the dolmens or single roomed graves with early dates were extended and used in the LN, which then could explain the EN/MN dates from multi-roomed graves. All of the burials in the multi-roomed graves were deposited in the larger inner room. In one case (Utbogården), a few human bones were recovered in the smaller middle room, but these bones were dated to the same time span as the ones in the larger inner room where the youngest burials also were identified (Appendix 1). Furthermore, the shorter graves are generally narrower than the longer multi-roomed graves, which does not fit the extended grave hypothesis considering grave shape and location of the burial remains.
In the case of the single roomed gallery graves with EN/MN dates, the evidence unambiguously points to early graves. Much suggests that some of the multi-roomed graves with early dates too were constructed in the EN/MN, but re-depositions of old bones cannot be excluded.
Misinterpreted dolmens or early gallery graves?
As already mentioned, there is an overlap in form and size between dolmens and gallery graves, and in these cases, it is challenging to classify the graves. Several megalithic graves in Falbygden have been reclassified over the years. Nedre Kapellsgården was previously described as a gallery grave and as a damaged passage grave (Cullberg 1961; Appendix 2), before it was classified as a dolmen by Blomqvist (1989). Slutarp was classified as a dolmen by Lindqvist (1911) and a gallery grave by Riksantikvarie ämbetet but is now reclassified as a dolmen (Blomqvist 1989; Sjögren 2003).
In this study, two further dolmens in Falbygden are reclassified gallery graves. We chose to classify Frälsegården/Gökhem 164 as a dolmen based on the size and the position above ground in a cairn. Backagården measured about 3 m but was still classified as a dolmen due to similar characteristics as the Slutarp dolmen and as the type two dolmens defined by Eriksen and Andersen (2014).
The graves here classified as gallery graves containing MN 14C dates do not all meet the criteria for dolmens according to Sjögren (2003) and Eriksen and Andersen (2014). Although Sjögrens definitions tolerate some overlap between the gallery graves and dolmens, the graves are still more similar to the gallery graves based on the size, orientation, the constructions below ground and the occurrence of ante-chambers (Appendix 2; Table 2). Of the 20 gallery graves containing MN finds, reported in Table A3, six had ante-chambers and eleven were longer than 3 m, while only six measured 3 m or less. Consequently, the early graves cannot solely be explained as misinterpreted dolmens.
In Västergötland, six of the seven gallery graves with MN 14C dates are between 3 and 7 m, and five are 3.5 m or longer. Even though graves of 3 m length or shorter could indicate a dolmen classification, 3 m is a common length of gallery graves, especially in southern Sweden. Three of the graves had ante-chambers and port-holes, construction details which are characteristic of gallery graves (Table 2).
The four single roomed graves are more difficult to fit in any of the conventional megalithic grave types. The 2.6 m long single roomed grave Rantens järnväg had a floor lower than the ground level supporting a classification as gallery graves, while the low number of slabs (three) is a common characteristic of dolmens. The nearby Rantens torgplats grave was described as similar to the former and contained the same type of amber bead (Appendix 1). However, the walls were constructed by two slabs each and it was probably constructed above ground (Appendix 2). Thus, it is possible that these two graves could be categorized as dolmens, although they are slightly wider than the dolmens (Appendix 2). The Blinningsberg grave was 5 m long and described as a single chamber open in the south containing two supposed niches (Appendix 2). The size is consistent with gallery graves and passage grave chambers, and niches are common in passage graves, although they also occur in dolmens and gallery graves. The opening in the narrower southern gable supports a classification as a gallery grave. However, it was only partially excavated and it is also possible that this is the remains of a passage grave chamber. The Rössberga gallery grave was constructed above ground but measured at least 3.5 m. Accordingly, it does not fit the classification of dolmens.
The two gallery graves with MNB dates found in Torsborg on Öland measured 3.5 m and consisted of a chamber and an ante-chamber. Parallels to the Danish Bøstrup graves, which were constructed in MNB, can be claimed. Two additional types of MNB gallery graves exist in Denmark: small closed stone cists without entrance and small trapezoidal Musse cists (Ebbesen 1985; Iversen 2015: 75). The small gallery graves in Falbygden with early dates were most likely all constructed with single open chambers and do not fit the Danish types. The only two small closed stone cist without an entrance, Torsagården and Kapellgatan, were constructed below ground and can by the earliest be dated to LNI. Thus, no similarities between the early Danish and Swedish graves can be observed.
The Backagården dolmen was oriented NE-SW, the most common orientation of the Västergötland passage and gallery graves included in this study, while the remaining three dolmens were roughly oriented E-W. The 3-m-long Ansarve dolmen on Gotland is also oriented E-W (Appendix 2). Maybe the Backagården “dolmen”, like some of the single roomed “gallery graves”, are local/regional subtypes of dolmens. This might suggest that the definition of dolmens needs to be corrected to encompass a wider range of grave constructions.
If the early dates instead define dolmens, then some of the graves now classified as gallery graves would be categorized as dolmens and the term gallery grave would be of no use. If instead some of the gallery graves in Västergötland are considered to be constructed already in the EN/MN, then the parallels observed between gallery graves in northern France and Germany make more sense. The WBK and SOM graves are dated to 3400 to 2700 cal BC, although many of them were reused in later times, some of the SOM graves were used to about 2000 cal BC (Guilaine 2011: 85; Müller 1998; Salanova et al. 2011). Kaelas (1967) stressed the similarities of the Västergötland gallery graves to the gallery graves dug into the ground from the Paris Basin and to the graves above ground in Brittany. She suggested immigrations of small groups with different building traditions into Västergötland. The SOM graves were generally built on slopes and dug into the ground, sometimes with several chambers and an ante-chamber as wide as the chamber and measure between five and 10 m, while the graves in Brittany above ground were much larger (Guilaine 2011: 85f). There are also obvious similarities between some of the large Västergötland gallery graves and the allées de l’Aude from southern France. These graves are multi-chambered with port-holes and open ante-chambers and were dug into oval mounds. The graves are generally 5 to 10 m long and date to 3500 to 2500 cal BC (Guilaine 2011: 88f). Several of the large gallery graves in Västergötland also have openings in one of the long sides, a common characteristic for some of the WBK graves (Schierhold 2009; Weiler 1996).
Considering the dating of the German and French gallery graves, a similar dating of the Swedish port-hole graves would be expected. Thus, the parallels observed in the morphology and construction details of the building traditions in these two areas is another argument for an early construction of the western Swedish multi-roomed gallery graves. However, a living tradition of building similar graves is not necessary. Older grave traditions, local or from far away, could have been the inspiration for recreating similar graves in a much later stage with the purpose of relating to earlier traditions or groups.
To sum up, the graves classified as gallery graves in this study containing EN/MN dates do not entirely fit the conventional definition of dolmens, although three of the single roomed graves might be atypical dolmens and a fourth a destroyed passage graves. Others are typical western Swedish gallery graves with ante-chambers, some of them with port-holes displaying close similarities to German and French gallery graves dated to around 3000 cal BC. If the multi-roomed gallery graves were constructed as early as some of the burials, animal bones and artefacts suggest, is still open for discussion. At this point, the material is still too small to draw any firm conclusions. Nevertheless, a new megalithic terminology might be needed to avoid preconceived notions of the conventional types and to emphasize the variation of shapes and appearance of contemporaneously constructed megalithic graves.
A reevaluation of grave type terminology
Are the conventional types of megalithic graves still valid or do we need new ways to think about the megalithic graves? Many of the morphological characterizations of megalithic graves, such as shape, form, orientation, the placement above or below ground, could partially be explained by the local environment and geology, the available building material and at what season the grave was constructed. Nevertheless, some deliberate choices are expected which might indicate variation or chronological trends. Figure 19 is an attempt to group the different graves in Västergötland, only considering the included graves. It is not meant as a typology of the megalithic graves, but a way to get a clearer view of the datings of the human remains and artefacts found in the sampled graves, with a special focus on gallery graves.
According to Table 2, many of the graves lack information about morphology and size due to several factors such as poor documentation, partial excavation or that the graves had been partly destroyed. The whole spectrum of various sizes and shapes has not been covered as many have not been excavated and some lack datable bone material. For example, there are few gallery graves above ground and no gallery graves larger than 8 m, as these are more common in the Precambrian areas of Västergötland where the preservation of bone material is poor.
The grave groups in this figure were mainly based on the 14C dates and finds as well as shape. In general, chronology seem to be independent of the size of the chambers, as already pointed out regarding the passage graves (Ahlström 2009; Sjögren 2003), although the size was also considered in some cases.
Group A includes all graves above ground consisting of chambers with a perpendicularly placed passage. In Falbygden, these graves are surrounded by mounds or cairns and the chambers measure between 2.7 and 17 m (Blomqvist 1989; Sjögren 2003). The14C dates of the human remains recovered in the 19 included passage graves have previously been discussed in detail and are shown with the dating of the accompanied finds (Fig. 19).
Group B is rectangular chambers with a longitudinal passage constructed below ground and is represented by one single grave (Carlsgården). The grave was covered by a low cairn and constructed by a 3-m-long chamber furnished with a half circular port-hole. Similar shapes are known, for example, Manered gallery grave, Lerum.
Group C includes rectangular single roomed chambers above ground constructed by four slabs with additional gable slabs. This group is represented by two graves (Slutarp and Backagården) 2.2 and 3 m long covered by mounds. In these cases, the human remains are dated to ENII and EN/MNA, with MNA artefacts in one of them (Fig. 19).
Group D consists of single roomed pentagonal graves with an opening above ground. Only one (Nedre Kapellsgården) grave is representing this group; however, this shape is known from other locations in southwestern Sweden, particularly at the coast.
Group E includes single roomed graves above or slightly below ground 3 m or shorter. Two graves located in Falköping stad (Ranten and Rantens torgplats), 2.6 and 3 m long, contained MNA finds and human remains, and in one of the graves, the 14C dates extended into MNB. This group also encompasses Frälsegården, a rectangular single roomed grave estimated to a size of 2 × 1 m, although the exact shape is unknown. This grave was covered by a low cairn and contained a skeleton dated to the MNA.
Group F consists of open single roomed rectangular graves above ground. Two graves (Blinningsberg and Rössberga), 3.5 and 5 m long, contained MNA artefacts and human bones from EN/MN and MNA. Both of these graves were originally covered by cairns. In a similar grave (Mikaelsgården) measuring 4.5 m a MNA find was recovered, while a human bone was dated to the transition between LNI and II (Fig. 19).
Group G comprises single roomed closed graves below flat ground. Two small graves (Torsagården and Kapellgatan) belong to this category: a rectangular chamber with artefacts dated to the LNI and human bones dated to LNI/LNII and a hexagonal chamber with LN finds and a skeleton dated to LNI.
Group H is represented by one trapezoid shaped grave (Fredriksberg) below ground with an ante-chamber in the narrower gable. The grave measured 5.3 m. The chamber contained LNI finds and human remains dated to LNI/LNII and LNII. A second possible grave belonging to this category is Brunnsgården with a port-hole and with LNI and LN artefacts and human remains dated to LNI/LNII to LNII/EBA (Appendix 2, Fig. 19). Another example of this type of grave is Nedregården, Våmb in Västergötland.
Group I comprises pear-shaped graves with ante-chambers in the gable and is represented by the 7.3 m long Helles grave with a port-hole. The grave contained a tanged blade arrowhead dated to MNB and LNII to EBA burials, (Appendix 2, Fig. 19). Timmele Ek and Jällby Östergården are other examples of graves with similar shape and size in Västergötland. Both graves had an opening in the long side, a characteristic found in several of the large gallery graves in Västergötland.
Group J includes rectangular and slightly irregular graves below ground with ante-chambers in the gable and port-holes. Five graves (Backa, Högebo, Tomtens kalkbrott, Skattegården and Lilla Balltorp), 4, 4, 4.5, 5.7 and 7.5 m long, contained LN and LNII finds and human remains dated to the transition LNI to II and into EBA. Högebo also contained EN/MN human remains and MN artefacts (Table 2, Fig. 19).
Group K consists of rectangular graves above ground with ante-chambers in the gable and port-holes. In a grave (Måns Nilsgården) measuring 4.8 m, artefacts as well as animal bone could be dated to MNA while a human bone was dated to LNII. A second (Berga) measured 2.9 m and contained human remains dated to LNI/LNII and artefacts dated to MNB and LN (Appendix 2, Fig. 19).
Group L comprises graves constructed by two rooms and an ante-chamber in the gable with two port-holes. The grave (Utbogården) that represents this group measured 7 m and was placed below ground and covered by a low cairn (Appendix 2, Fig. 19). This type of grave appears both below and above ground in the central parts of Västergötland and often measures around 8 m. The artefacts found in some of these graves can mainly be dated to LNII and EBA, even though MN and LNI finds also occur (Table A3).
Figure 19 clarifies the results already discussed in the previous sections. Group A and most single roomed graves (C, D and E) can be assigned to the EN/MN, while the early dates in the multi-roomed graves either can be explained by a first burial phase or reburials of old bones. Rectangular and hexagonal single roomed graves with few burials contain LNI burials, while in the other multi-roomed graves the LN burial sequence is later, at the transition between LNI and LNII (Fig. 19).
This section demonstrates that new ways of thinking about megalithic graves enable us to recognize new patterns. By applying the conventional typology, we risk to reproduce a simplified image of the megalithic varieties constructed during the different periods. This could also obstruct the possibility to identify and discuss local and regional variations. The tendency to classify graves which do not exactly fit the definition of dolmens and passage graves as gallery graves might also lead to a too great emphasis of homogeneity in the EN/MN megalithic phase and heterogeneity in the LN/EBA megalithic phase. Even though the variation of megalithic grave types is greatest in the LN/EBA, we have demonstrated that the variation was greater in the EN/MN than previously thought.
Contextualizing megalithic building in Västergötland
The results from the 14C dated human bones in Västergötland open up for several plausible scenarios. One possibility is that megalithic building consists of two separate traditions without any relation. Another scenario is that the megalithic tradition continued and transformed from the EN/MN into the LN and EBA. In both cases, the early dates in the gallery graves could be explained both by early construction of certain graves and the reburial of bones from older graves or relics. A third possibility, which does not exclude either of the two previous suggestions, is that the 14C dates in the megalithic graves reflect demographic fluctuations.
In Falbygden, the introduction of megalithic grave construction took place in the setting of the TRB complex at the end of the EN and intensified in the MNA. It is possible that various types of megalithic graves where built in several locations in Västergötland, some of which today are interpreted as LN gallery graves. It is also possible that the building traditions between different areas varied and that the large number of passage graves in Falbygden and few dolmens might reflect separate TRB groups of different origins or hierarchal levels of the society. It is probably more likely that the morphology of the passage graves and dolmens could be an expression of local developments. Some of the small dolmens and small single roomed gallery graves could be related to the passage graves and represent associated burial practices or burials of different categories of people within a society. Regarding the proportion of early dates in the dolmens and passage graves, it is probable that the dolmens were introduced slightly earlier than the passage graves but were also constructed and used simultaneously. Some of the multi-roomed gallery graves including the ones with port-holes were possibly built already in the EN/MNA and might have been constructed by people of a different background than the groups constructing passage graves.
During the MNB and the first part of the LNI, the burials in megalithic graves decrease drastically and seem to disappear, and no megalithic constructions can be dated to this time interval. Here two interpretations may be considered: new burial practices were introduced and megalithic traditions were abandoned, or the megalithic tradition continued to some degree, as a subculture, with few/sporadic burials which are not visible in our archaeological record at this point. A third possibility, which is not contradicting the two previous proposals, is that the decreasing number of dates reflect the demographic development in the area.
Regarding the first scenario, the megalithic successive burial is abandoned and other burial practices were implemented by force or voluntarily possibly in connection with new ideologies brought by BAC groups. Stray finds in Falbygden of battle axes and BAC pottery are strong indicators of BAC graves (Sjögren 2003) and a few actual graves have been described in previous literature (e.g. Sahlström 1932: 32f). Some reuse of megalithic graves occurs during the MNB, although the BAC finds are generally found in the entrance area of the megalithic graves indicating a different kind of use more related to the closing than a continued use of successive burials (Blank 2016). Parker Pearson and Reigner (2018: 59) suggested in analogy with Madagascar populations that the megalithic tradition in the Neolithic ceased because of the change from cereal cultivation to economies more focused on pastoralism with a greater everyday mobility, when new groups were established in the north European region. Megalithic building could also be an expression of prestige competition between groups in societies based on a feasting/ritual economy with a possible surplus production (Jeunesse and Denaire 2017; Wunderlich 2017), thus be related to prevailing social organization and economic conditions.
The reappearance of megalithic building and use in the LN could be interpreted as an attempt to recreate older traditions and to relate to mythical ancestry. Thus, local groups and the increasing influx of people from outside the area during the LN (Blank and Knipper in press 2020) could claim the right to various locations but also reinforce group identity in times of change. This could explain the high degree of LN reuse of megalithic graves (Blank 2016; this study). In this scenario, the early dates in the multi-roomed gallery graves might be reburied bones from older graves, which could be a way of relating the reinvented megalithic tradition with the older one. According to Vandkilde et al. (2017), the LN practice of constructing gallery graves was a reinvention of the previous megalithic tradition. The 14C dates indicate that the tradition reappears slightly after 2200 cal BC, with a peak of successive burial rituals in megalithic graves around 2000 cal BC and continues throughout the EBA.
The second scenario suggests that the megalithic tradition in fact was adapted to new practices and continued and transformed from the EN/MN building and burial traditions to the LN ones. In eastern Denmark, Iversen (2015) suggests that TRB norms and social structures continued into MNB and blended with the new SGC influences. For example, the TRB traditions manifested in the continued use of megalithic graves (Iversen 2015: 173f). In Falbygden, only a few examples of reused megalithic graves in the MNB exist, if only skeletal material is considered. In one of the gallery graves, Rantens gallery grave, the grave seems to have been used continuously from MNA and well into MNB. Two of the MNB individuals buried in this grave measured low strontium isotope ratios, indicating a non-local origin and a possible origin from southern Scania, the west coast or Denmark (Blank and Knipper in press 2020). Thus, the use or reuse of this kind of graves could be a local expression of merging practices between local TRB and non-local BAC groups and could partly explain the relatively low number of typical BAC graves in Falbygden.
Even though no megalithic grave construction could be dated to the MNB in Västergötland, two multi-roomed MNB gallery graves from Öland can be confirmed by 14C dates of several humans and by numerous artefacts typologically dated to this period. Thus, the knowledge of building these kind of graves already in the MN in Västergötland is not unlikely, especially considering the early dates of human remains and the MN finds recovered in some of these graves. The early construction of some of the gallery graves with port-holes also seems logical considering the obvious influences from for instance France and/or Germany.
According to the third scenario, the intensive use of megalithic graves in MNA and LNII and the distinct decrease in MNB and LNI partly represents population density in the area. This interpretation assumes that most of the population was buried in megalithic graves or that the burials in megalithic graves were proportional to the total number of burials/depositions of dead. The decrease starting in the end of MNA could be an effect of the Yersinia pestis, at ca 3000 to 2900 cal BC, found in Frälsegården passage grave (Rascovan et al. 2019). However, the effects of this need more evaluation. The pattern found in the burial frequency of megalithic graves in Västergötland also correlates with the suggested population decline that occurred in Norway in the MNB followed by an increase in the LN (Nielsen et al. 2019). According to Nielsen et al. (2019: 88f), the population decrease can be related to an increase of interpersonal violence and the presence of Yersinia pestis in Europe (Nielsen et al. 2019: 88f). In addition, a population decline is supported by an abandonment of TRB settlements at the transition between MNA and MNB, which in Falbygden can be exemplified by the Karleby settlements (Sjögren et al. 2019). The pattern of burial distribution in the megalithic graves also more or less correlates to the population dynamics suggested in Denmark and northern Germany (Feeser et al. 2019; Hinz et al. 2012).
Considering the 14C dates, there are two construction phases of megalithic graves, which are separated by about 300 years with no burials and by an even larger gap of about 500 years between the first burials (potential time of construction) in the graves. This corresponds to 10 to 17 generations and implies that the megalithic graves were built by people of different traditions. Although the variation of megalithic grave types in the TRB setting was larger than previously assumed, the burial practices seem more ritualized/standardized than in the LN/EBA period. Furthermore, the LN displays a higher degree of population dynamics with increased human mobility and variability in subsistence strategies than observed in MNA (Blank et al. 2018). Two separate phases consisting of rather homogenous TRB groups in the EN/MN and heterogeneous groups of people of different origins and traditions in the LN/EBA are here suggested, which could explain that the variety of megalithic grave types was larger during the LN.
Regional variation
The investigation of regional variation is limited by the uneven number of samples and graves (Table 1) and is therefore only intended to describe some tendencies. Nevertheless, in most regions represented by more than one megalithic grave, the 14C dates are separated in two phases with intensive use in MNA and LNII/EBA. On the Baltic island of Öland, the megalithic graves instead show continuous use into the MNB, LN and EBA.
According to the 14C results from human bones, the first burial phase appears contemporaneous, although a slightly earlier start can be suspected in Falbygden. ENII dates were only confirmed in dolmens, passage and gallery graves located in Falbygden and MN dates in gallery graves were only found in Västergötland and on Öland. In the case of early dates in Falbygden, this can be caused by the large amount of samples compared with the other regions but could also indicate a regional difference. Schulz Paulsson (2010) suggested an introduction of Scandinavian passage graves around 3500 BC, either developed in Västergötland and spread to Öland and Gotland or introduced somewhere from the south. The earliest individual (E from Landbogården passage grave, Falbygden) included in the above study (Schulz Paulsson 2010) was later re-dated to MNA (Sjögren 2011; Appendix 1). In a later publication, Schulz Paulsson (2017:307) instead suggests the megalithic graves from Gotland and Öland to be the first ones in Sweden. However, some of the earliest burials from the Ansarve dolmen turned out to be slightly younger when they were re-dated (Fraser et al. 2018; Appendix 1).
If only the inhumed skeletal remains are considered, there are no indications at this stage of earlier use of the megalithic graves from Gotland and Öland. With the new dates, the earliest dated individuals in passage graves as well as in dolmens (ENII) are found in Falbygden: Backagården dolmen and Rössberga passage grave (Figs. 8 and 9; Appendix 1). Nevertheless, there is a sample from in Mysinge passage grave with unknown δ15N and C:N values and a rather high δ13C, not included in this study, dated to the ENII (GrA-16,855, 4685 ± 40 BP, 3629–3367 cal BC, 95.4%). However, considering the dolmens and passage graves, the earliest 14C dates in Falbygden partly overlap the earliest dates in the other regions. The results do not support an internal chronological development from the rounded passage graves, common in Scania, to the T-shaped graves of Falbygden (Blomqvist 1989; Cullberg 1963; Tilley 1991). Instead our results favour the suggestion that the chamber forms of both dolmens and passage graves more likely are a result of regional differences (Persson and Sjögren 1995; Sjögren 2003).
Västergötland is the only region where EN/MN or MNA dates occur in gallery graves. Unlike in Denmark and on Öland, no constructions of megalithic graves are visible during the MNB in the available dates from Västergötland. In the case of early gallery graves, it is likely that this is a regional phenomenon. In general, the gallery graves in Västergötland deviate from the gallery graves found in the more southern regions with larger graves and more complex construction. No MN dates are known from the Scanian gallery graves, which generally are smaller and contain fewer burials. Based on dagger types, Ebbesen (2007: 23) claims that most of the Danish gallery graves were constructed in the transition between LNI and LNII. The Swedish smaller gallery graves might have been influenced by the Danish gallery graves, while the larger gallery graves were influenced by earlier European gallery graves (see below).
The second phase begins in the LNI, with only a few dates. The second peak occurs in the LNII in Västergötland and Uppland, while in the other regions, it is slightly later and concentrated to the EBA. In contrast to other regions, several Scanian gallery graves only contain EBA dates, indicating an EBA construction of gallery graves or a practice of clearing out older burials (Fig. 9). In the regions, where a considerable number of dates were included (Öland, Gotland, Västergötland, Uppland and Scania), the megalithic graves were used into BA period IV. The frequency of BA period IV dates is low, much lower than the dates from the previous period, which might indicate a continuous use of megalithic graves into period III, with sporadic reuse in period IV. Reuse of the megalithic graves also occurs during the LBA, IA and later periods (Appendix 1; Arne 1909; Blank 2016; Montelius 1873; Sjögren 2003; Strömberg 1971b; Weiler 1994).
Västergötland does seem to diverge from the more southerly regions, with burials from EN/MNA in all three types of megalithic graves and an intensive use in the LNII. This might reflect Falbygden as an important and densely populated region during the Neolithic, while the EBA peak in Scania and on Öland and Gotland might be connected with an increased population in the EBA.
In Denmark, 14C dates from burials in gallery graves suggest a use time between 2200 and 1600 cal BC (Frei et al. 2019: Table 1; Fig. A8), and the few available 14C dates from Norwegian gallery graves indicate a similar burial sequence (Østmo 2011; Fig. A9). Furthermore, the x14C dates from Danish Bøstrup cists confirm a first burial phase in the MNB (Fig. A8). Unlike in Västergötland, no EN/MNA dates occur in the Danish and Norwegian gallery graves.