Predictions about the genetic change from Single Grave to the Late Neolithic in Denmark

germanic-early-bronze-age

New open access paper Mapping human mobility during the third and second millennia BC in present-day Denmark by Frei et al. PLOS One (2019), from the Copenhagen group (including Allentoft, Sikora, and Kristiansen) of samples whose genomic profile will probably be published soon.

Interesting excerpts (emphasis mine):

We present results of the largest multidisciplinary human mobility investigation to date of skeletal remains from present-day Denmark encompassing the 3rd and 2nd millennia BC. Through a multi-analytical approach based on 88 individuals from 37 different archaeological localities in which we combine strontium isotope and radiocarbon analyses together with anthropological investigations, we explore whether there are significant changes in human mobility patterns during this period. Overall, our data suggest that mobility of people seems to have been continuous throughout the 3rd and 2nd millennia BC. However, our data also indicate a clear shift in mobility patterns from around 1600 BC onwards, with a larger variation in the geographical origin of the migrants, and potentially including more distant regions. This shift occurred during a transition period at the beginning of the Nordic Bronze Age at a time when society flourished, expanded and experienced an unprecedented economic growth, suggesting that these aspects were closely related.

denmark-late-neolithic-bronze-age-sites
Map of present-day Denmark illustrating locations of the burial sites.
The dashed black line marks the maximum advance stage of the last glaciation (Weichselian). Drafted with public domain data from Natural Earth (https://www.naturalearthdata.com).

Strontium isotope analyses

The results of our strontium isotope analyses are presented in Table 2 and listed in chronological order according to the radiocarbon dates (in sites with multiple individuals we start with the oldest radiocarbon individual). The strontium isotope data set reveals a wide range of values from 87Sr/86Sr = 0.70871 (RISE 23, from the site of Debel) to 87Sr/86Sr = 0.71788 (RISE 20, from the site of Karlstrup). Despite the difficulties of establishing the baseline range some of the herein investigated individuals may be classified as non-locals. A few individuals have tooth enamel signatures that lie just above the upper baseline limit of 87Sr/86Sr = 0.711 and therefore, the classification of these humans as non-locals should be considered with caution. Nevertheless, the significant proportion of individuals with relatively radiogenic values suggest that about a quarter of the individuals studied herein seem to have originated from other places than from those they were buried, and hence implying a continuous degree of mobility during the 3rd and 2nd millennia BC.

strontium-isotope-denmark-neolithic-bronze-age
Diagram plotting results of strontium isotope ratios versus calibrated radiocarbon dates of the individuals investigated. The grey band shows the “local” baseline.

Middle Neolithic

From the Single Grave Culture (SGC) which is closely related to the Corded Ware Complex in central and eastern Europe and dates from c. 2800 BC to 2200 BC, we analyzed seven of the at least ten individuals who were buried at the site of Gjerrild in eastern Jutland (Fig 1). Gjerrild is a key SGC site, as to date it has provided the most substantial skeletal material pertaining to this culture from present-day Denmark. However, it is not a typical SGC grave, but a megalithic chamber of the so-called “Bøstrup type”. The SGC pottery was decorated with cord or stamp impressions and the stone battle axes were a common feature of male equipment. Such shared traits in the Corded Ware Complex probably reflected shared occupational, social and religious characteristics. Apart from one individual who yielded a Bronze Age date, five individuals date within the period that spans from c. 2600 BC to 2200 BC, hence representing the middle and late SGC phases (Table 1 and S1 File). Of the seven individuals, three males, one female, two infants and one adult (only represented by a disarticulated mandible, and dated to the Bronze Age), all but one yielded strontium isotope signatures that fall within the local baseline range. Only the female (RISE 1283) has a more radiogenic strontium isotope signature of 87Sr/86Sr = 0.7127, which is similar to that of the male from Kyndeløse and might indicate non-local provenance. One of the individuals at Gjerrild, a mature-old adult male, who yielded a local signature (RISE 432) was accompanied by a D-type arrowhead and an amber bead which lay on his right side. He showed signs of inflammation on his lower legs, in particular on the left one. He had a healed trepanation (Fig 2). Another individual (RISE 73a, 1282), an adult male, was found with a type D arrowhead in the sternum (Fig 3).

denmark-late-neolithic-bronze-age
Strontium isotope, 14C results and sex and age determinations from individuals from the 3rd and 2nd millennia BC from Denmark presented in chronological order. Modified from the paper, see full image.

Late Neolithic I

We sampled individuals from a total of twelve different sites that date to the Late Neolithic period (2300/2250-1700 BC).

One of these sites is Hellested on Zealand (Fig 1 and S1 File), with four flat graves containing five individuals, four young males and one mature adult female. We conducted strontium isotope analyses of enamel from all five individuals, and our results point to two individuals being characterized by local strontium isotope values. One of these individuals, the female, was buried with no grave goods (RISE 53, grave B) while the other, a young male, was buried with a fragmented bone pin (RISE 56, grave F). The other three male individuals (RISE 54, 55, 57) yielded similar strontium isotopic values that lie slightly above the local baseline range. All these individuals had been buried with early flint daggers (type I and II), and one of them (RISE 57, grave A) additionally had a ring-headed pin (Ringkopfnadel) [56]. On the basis of the presence of this ring-headed pin, Lomborg [56] suggested that these individuals had connections with the Únětice culture. Furthermore, three of them have radiocarbon dates that overlap (RISE 55, 56 and 57; Table 1).

Another Late Neolithic site is Juelsberg on the island of Funen (central Denmark, Fig 1 and S1 File) which is a gallery grave that contained at least 19 individuals. We conducted strontium isotope analyses of tooth enamel on 8 out of the 19 individuals and two of them, a male and female, yielded ratios that suggest a non-local origin (RISE 30 and 32). The grave goods comprise a (Lomborg) type I flint dagger but also some non-local type of artefacts. These consist of an early type of bone pin (type 7) mainly found in south-eastern Scandinavia, and a barbed and tanged flint arrowhead of the west-European Bell Beaker type suggesting western connections. The middle adult female (RISE 32) yielded an 87Sr/86Sr = 0.7121 and the mature to old adult male (RISE 30) yielded a 87Sr/86Sr = 0.7112. The different Sr isotope signatures of these individuals imply that they might have originated from different areas, albeit their radiocarbon dates are very similar.

The gallery grave of Marbjerg, Zealand (Fig 1), yielded 17 individuals (S1 File), and we conducted strontium isotope analyses of tooth enamel on 11 of them. The majority of the individuals were males, but females and children, too, were present. Anthropological investigations of the individuals from this site, males as well as females, indicate a relatively high life expectancy with respect to that typical for this period (S1 Table). Our radiocarbon dates revealed that this grave was in use for several hundred years from the Early Late Neolithic (2210–2030 cal BC, RISE 39) to the Late Neolithic /Early Nordic Bronze Age Period (1770–1620 cal BC, RISE 41). Despite the long-term use of this grave, 10 of the 11 individuals studied herein yielded a very narrow and overlapping range of strontium isotope values between 87Sr/86Sr = 0.7096–0.7101. Their values suggest not only that these individuals were local but that their food sources were derived from the same area over the course of several centuries. Only the tooth enamel sample of one individual, a middle to mature adult male (RISE 40), yielded a higher value of 87Sr/86Sr = 0.7117, which seems to suggest a non-local origin.

Predictions about these samples

Strontium isotope analyses only show potential movements during an individual’s lifetime, which is normally useless to assess relevant migrations if the sampling is not big enough (see more on investigating population movements). Still, if a sampling like this one shows many potentially non-local individuals from different parts of Denmark deviating from the baseline at a certain period, you can infer that something is happening within Denmark and in nearby regions.

strontium-isotope-denmark-late-neolithic-bronze-age
Strontium isotope results of the 88 investigated individuals including Late Bronze Age individuals investigated previously. The grey band shows the “local” baseline.

Based on what we know now, I bet these are the most likely events in Denmark that marked the Nordic Late Neolithic with its Bell Beaker-related Dagger Period ca. 2400/2300 BC on:

  1. Sudden appearance of R1b-L23 lineages (probably R1b-U106 among them), originally from the Northern European Plain, ultimately from the Danube River Basin. R1a-M417 subclades, possibly prevalent in the previous period, disappear or appear rarely, to resurge later during the Bronze Age probably mostly as hg R1a-Z284, originally from the Battle Axe culture in Sweden, together with I1 – these resurgence events might be shifted to a later phase, though, and there might be some isolated R1a cases in the Danish LN, too.
  2. Shift of Middle Neolithic to Late Neolithic in the PCA away from the Corded Ware cluster and closer to the Bell Beaker cluster – whatever that means exactly for Danish SGC relative to Northern European Beakers, visible especially when enough samples are available.
  3. Evident sign of new incoming ancestry ultimately from Yamnaya-related populations, compared to earlier peoples of Corded Ware ancestry. Yes, even this far north, despite heavy admixture of Yamnaya-like Bell Beakers through exogamy with Corded Ware-like populations all the way to the north from the Danube Basin.

All this will support, once again, the expansion of Bell Beakers from Yamnaya settlers of Central-East Europe. That is probably what I will be reporting about the data as related to the Pre-Proto-Germanic homeland of the Northern European Plain, unless there is some big surprise, for example that R1b-U106 expanded later from Northern Germany, more clearly associated with later Barbed Wire Beakers or even Únětice movements, although I find this very unlikely at this point.

The above predictions are more or less evident to everyone, despite the current mistrust in the Yamnaya – Bell Beaker expansion route of North-West Indo-European, due to the prevalent nativist and/or reactionary trends in hobby population genomics and among academics. My main prediction is therefore about human behaviour:

(1) Seeing how the Copenhagen group started to describe recently South Scandinavian genetic and linguistic prehistory, their conclusions are predictable. From the introduction of this paper:

The 3rd millennium BC stands out as a period of migrations in western Eurasia, as pastoral steppe populations settled in temperate Europe after 2800 BC e.g. [1, 2]. This was also a period of cultural and genetic admixture e.g. [3]. From 1600 BC onwards, southern Scandinavia became more closely linked to the existing European metal trade networks (…)

See what they did there? No mention of the radical change that the Dagger Period brought to Scandinavia, in cultural or genetic terms (see e.g. here or here). Strange how the only thing that Kristiansen has changed since the 1980s – and only after the 2015 genetic papers – is his previous emphasis on the Dagger Period as the most relevant unifying cultural and population movement in Scandinavia, responsible for the formation of a common Nordic language, which is suddenly given as little weight as possible in all his publications, to support some imaginary continuity with the Corded Ware culture (see e.g. here or here).

(2) Only a few males from the Single Grave period are described in this sampling, and they are quite close to the arrival of Bell Beakers, so if someone is looking for closure about the “R1b from Corded Ware”, I bet there won’t be any. As with conspiracy theories of native Vasconic R1b-L51 hidden somewhere in Western Europe even after Olalde et al. (2018) and Olalde et al. (2019), the mythic native Nordic R1b-U106 of Corded Ware will remain hidden in some unsampled Corded Ware group in the minds of many, despite being already found in Bell Beaker-derived European EBA cultures of Bohemia and possibly of Hungary, too (ca. 2500-2200 BC, see SNP calls), apart from the Late Neolithic sample from Lilla Beddinge in Scania (ca. 2275-2032 BC, see SNP calls)

I hope that I am wrong, and that some scholar in the Danish group is capable of reporting the data as it is, even if it contradicts the theories of its leading archaeologist, Kristian Kristiansen. The apparent downplay of the increase in non-local origins of individuals during the Late Neolithic I period as they appear in this paper, as well as their summary of foreign migrations into Denmark which mysteriously stop with the arrival of “Steppe ancestry” ca. 2800 BC, make me think that a change in their narrative is not very likely. The cons of working with academic divos, I guess…

Related

Eastern pressure blade technology in west Scandinavia associated with WHG

New interesting preprint Ancient DNA from chewing gums connects material culture and genetics of Mesolithic hunter-gatherers in Scandinavia, by Kashuba et al. (2018).

Interesting excerpts (emphasis mine):

Mitochondrial genomes from all three individuals belong to the U5a2d haplogroup. (…) The mitochondrial U5a2d haplogroup is consistent with earlier published results for ancient individuals from Scandinavia, U5a being the most common within SHG. Of the 16 Mesolithic individuals from Scandinavia published prior to our study, seven belong to the U5a haplogroup, nine share the U2 and U4 haplogroups

We divided the SHG group into two groups: SHGa and SHGb (ancient individuals found in contemporary Norway and Sweden, respectively). We based this on both the geographical distribution and the previous studies demonstrating the close relation of SHGa to EHG group and SHGb to WHG group. To further explore the demography within the SHG group, we compared the ancestry of BLE individuals within SHGa and SHGb groups. This comparison revealed a high relative shared drift between BLE individuals and the SHGb group

scandinavia-hunter-gatherer-admixture
Admixture analysis showing the major mode for K=15. The figure represents 11 runs out of 20 replicates (Greedy algorithm ran with the Jaccard distance and a 0.97 similarity threshold)

The results from Huseby Kiev allow us to finally connect the SHG group with the eastern pressure blade technology. However, the higher genetic affinity between Huseby Kiev individuals and the WHG group challenges the earlier suggested tie between eastern technology and EHG genetics. Our results suggest either early cultural transmission, or a more complex course of events involving both non- and co-dependent cultural and genetic admixture.

huseby-kiev

Seeing how culture is indeed usually associated with the expansion of a certain population, especially at such an early date, I guess this similarity with WHG of incoming eastern peoples comes from an originally EHG population expanding into a mainly WHG area in the west (similar to what happens e.g. with Bell Beakers), or being replaced later by a WHG population which adopted the culture (similar to what happened with late Corded Ware populations in central-east Europe after the expansion of Bell Beakers).

Unlike later periods, it will always be difficult to judge such ancient population movements with few samples covering thousands of years… Probably specific Y-DNA haplogroups would help differentiate between both expanding populations from east and west.

Related

The preferred northwest passage to Scandinavia

Pontus Skoglund writes (and shares publicly) his perspective on early postglacial migrations of hunter-gatherers into Scandinavia, in Northwest Passage to Scandinavia (Nat. Ecol. Evol.): an initial migration from the south and a second coastal migration north of the Scandinavian ice sheet.

He sums up the recently published Open Access paper Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation, by Günther, Malmström , Svensson, Omrak, et al. PLoS Biol (2018) 16(1): e2003703, based on preprint at BioRxiv Genomics of Mesolithic Scandinavia reveal colonization routes and high-latitude adaptation (2017).

Abstract:

Scandinavia was one of the last geographic areas in Europe to become habitable for humans after the Last Glacial Maximum (LGM). However, the routes and genetic composition of these postglacial migrants remain unclear. We sequenced the genomes, up to 57× coverage, of seven hunter-gatherers excavated across Scandinavia and dated from 9,500–6,000 years before present (BP). Surprisingly, among the Scandinavian Mesolithic individuals, the genetic data display an east–west genetic gradient that opposes the pattern seen in other parts of Mesolithic Europe. Our results suggest two different early postglacial migrations into Scandinavia: initially from the south, and later, from the northeast. The latter followed the ice-free Norwegian north Atlantic coast, along which novel and advanced pressure-blade stone-tool techniques may have spread. These two groups met and mixed in Scandinavia, creating a genetically diverse population, which shows patterns of genetic adaptation to high latitude environments. These potential adaptations include high frequencies of low pigmentation variants and a gene region associated with physical performance, which shows strong continuity into modern-day northern Europeans.

The ice sheet distribution – which did not improve nuch for thousands of years – was clearly the greatest barrier for potential migrations in the region.

baltic-sea-10000-bc
Baltischer Süßwassersee Vorläufer der Ostsee vor 12.000 Jahren, by Juschki and Koyos at Wikipedia

See also: