Starting around 4800 BC, a new cultural horizon had begun to become dominant in Western Europe. Massive stones were used to construct burial sites, monuments and religious sites. Some of the most famous remnants of this ancient culture includes Stonehenge in England and Newgrange in Ireland, as well as the Almendres Cromlech in Portugal. Recent DNA studies such as Cassidy et al, 2020 and Sánchez-Quinto et al, 2019 have revealed to us exactly who the builders of these fascinating megaliths were, and where they came from.

An EEF culture with an elite class descended from hunter-gatherers?

The people of the megalithic cultures show a somewhat uniform genetic profile. Their ancestry was overwhelmingly Early European Farmer from early Cardium Pottery groups of EEF. They also carried small amounts of WHG ancestry. No surprise there. However, what is so remarkable about many groups of megalith builders is that they almost exclusively carried the Y-DNA haplogroup I2. Today, I2 is common in the Balkans. But back then, from Portugal to France, to Britain and to Scandinavia, the males of these megalithic cultures almost all belonged to haplogroup I2. Keep in mind, they still had mtDNA lineages typical of Anatolian farmers, and most of their autosomal DNA was still like that of Anatolian farmers. Only the male lines seem to have been replaced. This is especially interesting because the Y-DNA haplogroup that is the most associated with EEF from Anatolia is G2a. In early farmer cultures in Europe, G2a was very common. But at one point, there was some sort of resurgence of local hunter-gatherer paternal markers (I2). It’s currently not known how exactly this happened, but it seems unlikely that the Anatolian farmers who carried haplogroup G2a just willingly allowed hunter-gatherers to replace them and practically eradicate their paternal line from the gene pool. A more realistic guess is that there was some kind of violent takeover where local hunter-gatherers “took control” of already existing agricultural societies.

Judging by the currrent DNA record, this takeover appears surprisingly coordinated. It happened around the same time in many different places and it is only after this replacement of G2a by I2 that we can observe the megalithic cultures kicking off. This phenomenon of a wide-scale resurgence of WHG paternal lines seems to have started in France, likely somewhere in the Paris basin. It is possible that the megalithic traditions emerged as some kind of new religion, closely tied to the same material culture and patrilineal society where the males almost always show the same I2 Y-DNA but the women show a more heterogeneous genetic profile in terms of both autosomal DNA and mtDNA. It is in fact remarkably similar to some customs practiced by the Proto-Indo-Europeans of the Yamnaya horizon.

Let’s leave the more gruesome details of a possible hunter-gatherer takeover of EEF cultures out of this article. What is safe to say is that the advantages in physical fitness combined with knowledge of local terrain may have been deciding factors in what allowed for this replacement of G2a lineages by I2 lineages, thus paving way for what would become the megalithic cultures of Western Europe.

The 2020 study “A dynastic elite in monumental Neolithic society” examined the DNA of ancient skeletons from the Neolithic that were buried at Newgrange. To any of you who may have seen some sensationalist headlines about an “inbred elite” ruling over the people at Neoltihic Newgrange, be aware that there is some truth to that statement. If we look at the male sample labelled NG10 from Cassidy et al, 2020, we can observe one of the best examples of inbreeding in the ancient DNA record. His parents were determined to have been so closely related that they were assumed by the authors of the study to have been either a father/daughter or brother/sister couple. Yes, you read that right.

The elites buried in passage tombs were found to be significantly more closely related than other people buried in common tombs. Regardless of geographic distance between the passage tombs (Eastern vs Western Ireland). The skeletons of elites from the passage tombs also display signs of a more meat-rich diet and less manual labour. So, what we see here is a family of elites that may have practiced inbreeding as a way to keep power in the family.

Megalithic cultures in Iberia seem to have been less patrilineal and patriarchal than the ones in France, Britain, Ireland and southern Scandinavia given their more diverse Y-DNA lineages. DNA from EEF groups in what is now Spain and Portugal certainly has yielded a lot of I2, but they also show high frequencies of G2a and even more rare lineages like Y-DNA haplogroup H. Samples from these people display very uniform ancestry from Cardium Pottery groups, less WHG admixture than the French EEF, and no admixture from LBK farmers.

Now, while the men carrying I2 lineages seem to have been involved in a rather dramatic replacement of men carrying G2a lineages in some EEF cultures during the early stages of the European Middle Neolithic, they would relatively soon come to get a taste of their own bitter medicine. Which brings us to the arrival of the Bell Beaker culture…

Brutal extermination of megalithic men? The arrival of the Beaker folk

The Beaker folk of the final Neolithic and early European Bronze Age belonged to a highly expansionistic and fairly violent culture. Their distinct pottery is associated with the movements of males carrying haplogroup R1b of various subclades and WSH ancestry in Western Europe. It’s not yet clear-cut if we can speak of the Bell Beaker phenomenon as a genetic entity or just a cultural phenomenon, but in archaeogenetic terms Bell Beaker is often associated with the Dutch Beaker folk who brought steppe ancestry into Britain and Ireland and replaced the previous Neolithic inhabitants as well as their language and culture. This replacement didn’t happen instantly, but took a few hundred years as the Bell Beaker immigration spanned a few generations. It is unknown exactly how this replacement took place in Britain. Below is a chart with Y-DNA data from Olalde et al, 2018 that very clearly shows this extreme turnover in paternal lines.

The authors of the study were able to demonstrate a shift from a near 100% frequency of I2 to a 90-95% frequency of R1b in just a few generations. That is arguably one of the most substantial replacements of a population that has ever been recorded in both prehistory and history. Among present-day British men, haplogroup R1b reaches roughly 60%. That’s likely a much lower number than it would have been during the Bronze Age, mostly due to the introduction of J and E lineages during Roman times, and haplogroups I1 and R1a through Germanic migrations (Anglo-Saxons, Vikings). However, it should be kept in mind that Germanic migrations also brought a sizeable amount of R1b into Britain, mainly but far from exclusively of the R1b-U106 branch. We still do not know much about the exact Y-DNA composition of the Anglo-Saxons. So far all we have is one male Anglo-Saxon sample, sample NO3423 from Martiniano et al, 2016. He belonged to haplogroup I1-S107. While the Anglo-Saxons definitely carried significant amounts of I1 (like all Germanics do), they will almost certainly turn out to have carried a whole lot of R1b as well. Likely in similar frequencies as modern Brits do, or even higher. The Anglo-Saxons will likely turn out to also have carried R1b-P312 in significant frequencies. An upcoming study by the Max-Planck Institute in Germany that examines the genetic legacy of the Anglo-Saxon migration into Britain is guaranteed to gives us more insight into the Y-DNA composition of the Anglo-Saxons.

Given the significant Germanic influence on paternal lineages in England, Wales and Scotland, we may instead look to Ireland to get a better idea of what the Y-DNA situation was like in Britain after the Bell Beaker conquest. The Irish derive the bulk of their ancestry from the Beaker folk, and have a frequency of R1b that approaches 86%. With that in mind, even the Irish had a higher frequency of R1b in the Bronze Age than in modern times. A small percentage of Irish males also carry I1 and R1a, mainly due to Viking incursions. This really goes to show just how serious of a population replacement the Bell Beaker invasion of Britain was.

Now wait until you see the numbers for Iberia.

Below is data from another study by Olalde and colleagues showing the change of male haplogrup frequencies in Iberia.

In the upper right corner we can see the shift from the haplogroups of the Iberian Neolithic farmers (I2, G2a, H) to a near 100% frequency of R1b. Much like that of modern Spanish and Portugese people, with the exception that Bronze Age Iberians may actually have had an even higher frequency of R1b than present-day Iberians due to later movements from North Africa into Iberia (where a small amount of E1b lineages is introduced, although it is possible that most E1b in Iberia is quite old) and movements from Germanic tribes during the Migration Period (where a minor introduction of R1b-U106, I1 and R1a lineages occurs, as well as a re-introduction of some more northern and central European I2 lineages).

Differences between the outcomes of Bell Beaker expansions in Britain and Iberia

The present-day British population has a strong WSH (Western Steppe Herder) component, much like the Bell Beaker people from the Netherlands did (although the Beaker folk had a tad bit more WSH admixture than present-day Brits). British people do have a lot of EEF ancestry as well, but what’s so interesting is that it does not seem to be from the Neolithic people of Britain. Rather, the bulk of the EEF component among Brits probably comes from Atlantic farmers who lived in France and from Central Europe (likely from the Globular Amphora). These EEF components would have been picked up by the Beaker folk prior to their invasion of Britain and after it, as more Beaker folk from the continent came. As for the EEF group that built Stonehenge and the likes, they mostly seem to have vanished. It is unknown what happened to them, but given the almost total disappearance of their Y-DNA haplogroups, it’s quite likely that they were outcompeted either by violent means or by disease (possibly carried by the Beaker folk and brought into Britain). I would bet on the former. Although a severe replacement did take place, Neolithic British enclaves probably persisted in some areas, later contributing to a slight re-emergence of EEF ancestry.

The case of Iberia is a little bit different. If we look at present-day Spaniards for example, we can see that they display a very high amount of EEF ancestry from the Cardium Pottery farmers. They also have significant Yamnaya (WSH) admixture, but low levels of admixture from Mesolithic WHGs. The genetic profile of modern Iberians tells us that they largely descend from these Cardium Pottery farmers, specifically on the maternal side. This of course means that the contribution of steppe DNA was fairly small and strictly gender-biased. It does not appear that the Cardium Pottery females disappeared from Iberia. Rather they seem to have been taken as brides by males with steppe-derived paternal lines. Therefore it doesn’t seem that likely that it was a disease that wiped out the Neolithic and Chalcolithic farmer males of Iberia. While plagues can sometimes affect males disproportionately due to the way our immune systems work, they wouldn’t magically have culled all the men and left the women alive. Rather, it seems like there was either a violent disposal of Neolithic Iberian males or some kind of selection for men with steppe ancestry took place. A selection like that also seems unlikely, because while selection through elite dominance in ancient populations often made certain haplogroups skyrocket in frequency, it did not make it impossible for low-status males with other lineages to pass on their genes. However, the current archaeological record does not show evidence of increased violence during the Bell Beaker expansion to Iberia. Perhaps future discoveries will change this.

The modern Basques show slightly different ancestry proportions and are more like Iron Age Iberians, with quite a lot more WHG ancestry than Spanish people from other regions of Spain. They are not, however, some archaic Mesolithic/Neolithic remnant as their language would suggest. Interestingly enough, a study by Fregel et al, 2020 showed that Bell Beaker ancestry spread as far as to the indigenous inhabitants of the Canary Islands. Guanches were found to have harbored a certain amount of Bronze Age European admixture, which was believed by the authors of the study to have spread alongside the Bell Beaker pottery that has been found as far as North Africa.

Summary

Rich, and for their time, complex megalithic cultures dominated large parts of Europe in the Middle Neolithic. Capable of building impressive structures like Stonehenge and Newgrange, these megalithic cultures spread rapidly and would soon be found from Portugal to southern Scandinavia.

Then something happened in Britain, France and Iberia. It happened roughly around the same time. A people bringing bronze technology, Western Steppe Herder ancestry and a warlike Indo-European culture arrived. In just a few generations, practically all the Y-DNA haplogroups of the local men seem to have been replaced by the newcomers. In the ancient DNA record we are able to observe a near 100% frequency of I2 in many of the megalithic cultures, but with the entrance of the Bell Beaker culture a shift occurs and we are instead able to observe an almost 100% frequency of R1b lineages in Bronze Age Iberia and Britain. Today, R1b is by far the most common haplogroup in both Iberia and in Britain. Had the Bell Beaker migrations never happened, that would not be the case.

References:

H. J. Fleure and H. J. E. Peake, Megaliths and beakers (1930) https://www.jstor.org/stable/2843859?seq=1

Olalde (2017): The Beaker Phenomenon and the Genomic Transformation of Northwest Europe https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5973796/

Lee et al (2012): Emerging genetic patterns of the european neolithic: Perspectives from a late neolithic bell beaker burial site in Germany https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.22074

Cassidy et al (2020): A dynastic elite in monumental Neolithic society https://www.nature.com/articles/s41586-020-2378-6#Sec14

Sánchez-Quinto et al (2019): Megalithic tombs in western and northern Neolithic Europe were linked to a kindred society https://www.pnas.org/content/116/19/9469

Martiniano et al (2016): Genomic signals of migration and continuity in Britain before the Anglo-Saxons https://www.nature.com/articles/ncomms10326

Fregel, Rosa et al (2020): The demography of the Canary Islands from a genetic perspective https://pubmed.ncbi.nlm.nih.gov/33295602/

Booth et al (2021): Tales from the Supplementary Information: Ancestry Change in Chalcolithic–Early Bronze Age Britain Was Gradual with Varied Kinship Organization https://www.cambridge.org/core/services/aop-cambridge-core/content/view/5B71BE0F34927E0A7199A6A568DAB3BC/S0959774321000019a.pdf/tales_from_the_supplementary_information_ancestry_change_in_chalcolithicearly_bronze_age_britain_was_gradual_with_varied_kinship_organization.pdf

Haak (2015): Massive migration from the steppe was a source for Indo-European languages in Europe https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5048219/

Mathieson (2015): Genome-wide patterns of selection in 230 ancient Eurasians https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918750/

Olalde (2019): The genomic history of the Iberian Peninsula over the past 8000 years https://science.sciencemag.org/content/363/6432/1230.abstract

© Genomic Atlas 2021