From the Eneolithic to the Middle Bronze Age vast areas of Northern Europe and Central Asia were inhabited by a series of highly mobile and innovative groups that mostly relied on pastoralism for subsistence and, judging by their warlike grave goods, didn't mind a bit of biffo.
In Europe, where they first appeared, their archeological remains are generally classified as part of the Corded Ware Culture (or its Battle-Axe and Single Grave offshoots), and in Asia, where they expanded rapidly from the Trans-Urals to the Pamirs and south Siberia, as part of the Sintashta, Petrovka and Andronovo cultures.
It's likely that these groups had a profound impact on the Bronze Age world, including on Mycenaean Greece and Hittite Anatolia. The Sintashta Culture, for instance, is credited with the development of the spoked-wheel chariot, which became widely used in warfare all the way from Egypt to China.
Unfortunately, a lot of nonsense has been written on this topic in the past. In my view, one of the most sensible and up do date sources currently online is the thesis The Origin and Spread of the War Chariot by Elias Manuel Morgado Pinheiro.
Indeed, the obvious awesomeness of these ancient people has stirred much controversy about their origins and legacy. The academic consensus is that they were closely related, and that at least some of their ancestors were early Indo-Europeans from Eneolithic Eastern Europe. But a few archeologists have argued that the Corded Ware Culture was native to Central Europe, and others that the Sintashta population arrived in the Trans-Urals from Iran or even Syria.
Moreover, linguists generally consider the Sintashta/Andronovo people as the most likely candidates for the Proto-Indo-Iranians, and thus the precursors of the Indo-Aryans. But this is contested by many Indologists, who prefer to see the deepest roots of the Indo-Iranians closer to India and often oppose the idea of an Aryan conquest of South Asia during the Bronze Age.
In the near future, probably within the next couple of years, ancient genomics will leave very little room for debate in these matters and the arguments will cease, at least in mainstream academia.
But we already have a reasonable collection of ancient DNA from the relevant archeological cultures. Does it back the general consensus? Let's take a look, starting with the Y-chromosome data sorted by culture and chronology. The bracketed numbers are the sample sources, which are listed at the bottom of the post.
Corded Ware, Germany, 4600 BP, Individuals 2,3,4 , R1aFascinating stuff. Keep in mind also that at higher resolution, most, if not all, of these R1a lineages are actually R1a1a1, which is estimated to be only around 5,000-6,000 years old based on full Y-Chromosome sequences. In other words, these groups were certainly closely related, and in large part the descendants of a patriarch who lived no earlier than the Middle or even Late Neolithic.
Corded Ware, Germany, 4348 BP, I0104 , R1a
Corded Ware, Germany, 4161 BP, RISE434 , R1a
Corded Ware, Germany, 4124 BP, RISE436 , R1a
Corded Ware, Poland, 4117 BP, RISE1 , R1b?
Corded Ware, Germany, 4015 BP, RISE446 , R1a
Corded Ware, Poland, 3762 BP, RISE431 , R1a
Battle-Axe, Sweden, 4025 BP, RISE94 , R1a
Battle-Axe?, Sweden, 3736 BP, RISE98 , R1b
Sintashta, Trans-Urals, Russia, 3775 BP, RISE386 , R1a
Sintashta, Trans-Urals, Russia, 3626 BP, RISE392 , R1a
Andronovo, South Siberia, Russia, 3600 BP, S07 , C
Andronovo, South Siberia, Russia, 3600 BP, S10 , R1a
Andronovo, South Siberia, Russia, 3600 BP, S16 , R1a
Andronovo, Altai region, Russia, 3119 BP, RISE512 , R1a
Now, based on that list it might seem as if both R1a and Corded Ware were indeed native to North-Central Europe. But this is not so.
R1a appears to be an Eastern Hunter-Gatherer (EHG) marker that in all likelihood failed to penetrate west of present-day Ukraine until the Late Neolithic, because it's missing in all the relevant samples before this period. So it probably first arrived in Central Europe with the Corded Ware people. We know that the Corded Ware people were foreign to Central Europe because their genome-wide genetic structure is starkly different from that of the Middle Neolithic farmers who lived there before them.
This is easy to demonstrate. The Principal Component Analyses (PCA) below show where two ancient samples cluster alongside a variety of present-day West Eurasians from the Human Origins dataset . Note that Esperstedt_MN, a Middle Neolithic sample from a Baalberge Group burial in east-central Germany , looks more at home in Sardinia than Central Europe. On the other hand, the Corded Ware sample , also from east-central Germany, is sitting at the other end of the plot, among groups from the Volga-Ural region and the lone Saami.
I'll throw in a few more PCA featuring Corded Ware, Battle-Axe, Sintashta and Andronovo genomes that offered enough data to be placed on the plots with a high degree of accuracy . Note that the only clear outlier is RISE512, an Andronovo sample with an inflated level of East Eurasian admixture. If you're having trouble finding the ancient samples, download the PDF files and use the PDF search field.
However, the meat and potatoes of ancient genomics are formal statistics. So in part 2 of this series I'll explore the genetic ancestry and legacy of the so called badasses of the Bronze Age using the ADMIXTOOLS software package.
1. Haak et al., Ancient DNA, Strontium isotopes, and osteological analyses shed light on social and kinship organization of the Later Stone Age, PNAS, Published online before print November 17, 2008, doi:10.1073/pnas.0807592105
2. Keyser et al., Ancient DNA provides new insights into the history of south Siberian Kurgan people, Human Genetics, Saturday, May 16, 2009, doi: 10.1007/s00439-009-0683-0
3. Haak et al., Massive migration from the steppe is a source for Indo-European languages in Europe, bioRxiv, Posted February 10, 2015, doi: http://dx.doi.org/10.1101/013433
4. Allentoft et al., Bronze Age population dynamics, selection, and the formation of Eurasian genetic structure, Nature 522, 167–172 (11 June 2015) doi:10.1038/nature14507
Genetic substructures among Late Neolithic/Bronze Age Scandinavians