Collapse of the first R1a empire

[Pip]

One strand of R1a seems to have expanded rapidly between 3,100 BC and 2,400 BC, its population and culture spreading over huge areas of Northern, Eastern and Central Europe. But by around 2,300 BC, its culture had virtually disappeared, together with most sections of its population. Its only remaining thriving branch was a North Eastern one (Z283 from Poland and the Baltic states). Its only other significant surviving branch (Z93) also appeared to shrivel, but managed to re-establish itself several centuries later outside of Europe - from the Caucasus Southwards and Eastwards.
What were the main causes of its collapse? Which other haplogroups, if any, immediately replaced it?

[Twilight]

Hello there Pip, welcome to Eupedia. Although R1a did spread rapidly from Central Europe to India, the R1a clan didn’t quite see themselves that way 3,100 BC. If you look at Eupedia’s R1a Page, you will notice that R1a was present in the ancient Germanics, Balto-Slavs, Iranians, Mycenaeans and Turkic tribes.




https://www.eupedia.com/europe/Haplo...1a_Y-DNA.shtml

[Pip]

Yes, R1a itself was widespread and its many carriers did not form an empire. My interest is just in the single strand of R1a (a section of M417) that appears to have expanded, developed and dispersed rapidly during the first half of the third millennium BC, apparently mixing little with other haplogroups and stamping a similar culture wherever it spread. Only two small sections of it have survived - the Polish/SE Baltic section and a later Asian offshoot.

I wonder what caused it to crash, why the Polish/SE Baltic section continued to thrive, why the offshoot should have transposed itself to Asia, and which other haplogroup/s filled the gap that it left?

[Twilight]

I see now, that is a really good question. I found something interesting. According to DW Anthony’s book “The horse the Wheel and Language”. The steppelands were getting cold and dry, but with the invention of the war Chariot the Indo-Aryan-Iranians tribes can move from great distances. The chariot is so prized that the chariot is even mentioned in the Hindu Ratha Kalpana; the Chariot is our body and our intellect is our driver.

The first Sintashta settlements appeared around 2100 BCE, during a period of climatic change that saw the already arid Kazakh steppe region become even more cold and dry. The marshy lowlands around the Ural and upper Tobol rivers, previously favoured as winter refuges, became increasingly important for survival. Under these pressures both Poltavka and Abashevo herders settled permanently in river valley strongholds, eschewing more defensible hill-top locations.^[8]
The Abashevo culture was already marked by endemic intertribal warfare;^[9] intensified by ecological stress and competition for resources in the Sintashta period, this drove the construction of fortifications on an unprecedented scale and innovations in military technique such as the invention of the war chariot. Increased competition between triba may also explain the extravagant sacrifices seen in Sintashta burials, as rivals sought to outdo one another in acts of conspicuous consumption analogous to the North American potlatch tradition.

https://en.m.wikipedia.org/wiki/Sint...REFAnthony2007
https://www.google.com/amp/s/mindhol...he-horses/amp/

[eastara]

There was a population hiatus on the Balkans from 2400 to 1300BC possibly due to climate change.
After the end of the Ezero Culture, there was a hiatus from 2400 to 1300 BC, in which the Balkans were depopulated almost completely. Climate change, warming and droughts have been found to have forced this pastoralist (European-Asian) population to seek new better places to live in.

[Pip]

Thank you for the last two helpful posts.

Yes, I think climate change could have been a significant cause. With a few minor exceptions, a Balkan population hiatus ties up with a hiatus in the DNA data.

However, this raises a few other questions:
Why did Western (German) R1a-M417 collapse too? Perhaps partly for additional reasons - e.g. pressure from R1b-L151?
Why did South Eastern Baltic R1a-Z283 continue thriving? Perhaps due to more amenable weather conditions there, or perhaps greater collaboration with neighbouring groups?
Was the Sintashta offshoot a major ancestor of modern populations? Or perhaps its DNA didn't survive to any significant degree, and a related more Southerly (Caucasus vicinity) group developed more successfully instead?

I suppose you would have to ask why mobile communities fleeing cold, dry weather would travel Eastwards towards Siberia, rather than to the West or South, unless conflict with other communities in these areas was a further reason for the collapse and disintegration?

[markod]

When Bell Beaker encountered Corded Ware in Bronze Age Central Europe, the latter general had an inferior position. The archaeological record shows Bell Beaker to be richer, more developed, more universally armed. I believe the first encounter between Bell Beaker and CW took place in Switzerland, where the former became dominant relatively quickly. In southern Germany BB males have been found to practice large-scale female exogamy, which could have contributed to the decline of previously widespread Y-DNA haplogroups. But more importantly BB offshoots like Unetice & Urnfield became the dominant cultural spheres in Central Europe until the Iron Age.

[Pip]

Yes, DNA data would suggest a two-pronged migration of R1b-L151 into R1a Corded Ware territory - R1b-U152 into Switzerland and Southern Germany and R1b-U106 into North Western Germany and Southern Scandinavia. Perhaps that, together with climate change, led to the weakening and ultimate collapse of R1a-M417's dominant position?

Yes, perhaps exogamy in R1b-L151 was an important factor too, as its replacement of R1a-M417 in Central Europe seemed to lead to a resurgence of some other haplogroups (e.g. E-V13, G-PF3345 and I1) with whom L151 might have inter-mixed.

It looks like Eastward-migrating remnants of M417 Corded Ware struggled, at least in the longer term, as DNA data would suggest that a section of them relocated to Southern Asia, and the rest were ultimately replaced by other R1a-M417 (Z283) expanding later into their territory from the South Eastern Baltic.

[Ygorcs]

Yes, R1a itself was widespread and its many carriers did not form an empire. My interest is just in the single strand of R1a (a section of M417) that appears to have expanded, developed and dispersed rapidly during the first half of the third millennium BC, apparently mixing little with other haplogroups and stamping a similar culture wherever it spread. Only two small sections of it have survived - the Polish/SE Baltic section and a later Asian offshoot.

I wonder what caused it to crash, why the Polish/SE Baltic section continued to thrive, why the offshoot should have transposed itself to Asia, and which other haplogroup/s filled the gap that it left?

Beside the expansion of other haplogroups, it's also possible that the "Polish/SE Baltic" R1a subclade simply became more successful than the others and replaced them - possibly a social/cultural development associated with the spread of Balto-Slavic languages as Proto-Balto-Slavic is estimated to have been spoken as late as 2000-1500 BCE, well after the initial spread of CWC -, so it was not just a case of external pressure or population turnover (especially because many areas of Central/North/Northeast Europe are still today heavily CWC-like, let alone 3000 years ago), but also probably at least in part (and in some regions) an internal affair of the relative success of one strand of R1a in detriment of others that were closely related to it and belonged to the same cultural horizon. Even in Scandinavia/Northern Germany, around the birthplace of Proto-Germanic, R1a subclades remained a relevant minority, didn't they? In a heavily tribal and, to increase inter-group competition even more, clan-based society, I think it's not unexpected that, given the lack of coordination and social cohesion as if they were indeed part of one and the same polity, given enough time only a few more sucessful patrilineal clans and tribes, associated with ancestral Y-DNA lineages, will overwhelm the others and became totally dominant in a much larger area than the original one.

[Pip]

Yes, I suspect the relative success of the Polish/SE Baltic subclade was indeed a factor in the demise and displacement of the others. However, it looks like only one of several factors, as the expansion and development of this subclade out of its core zone looks relatively belated and gradual in comparison to the swift incursions of R1b Bell Beaker and the swift wholesale outward movements of Z93 East and South Eastwards.

Yes, there was possible early mixing of some R1a-L664 and R1a-Z283 components within a proto-Germanic Scandinavian/far North German population, but R1a-Z93 looks separated from these early on, and other R1a lines within Germany and Central Europe either shrivelled or died out.

[Pip]

Other forum users have identified 3 contributory factors in early R1a's collapse:
1. Pressure from more developed and universally-armed Bell Beaker in Central Europe,
2. Inhospitable climate arising in the South East,
3. North Eastern R1a replacing core R1a.

The only core R1a that did not die out was a few minor strands of R1a-Z93. These strands appear to derive from Central Europe, having the greatest autosomal similarity to German Corded Ware. However, DNA data seems to indicate that their subsequent development only occurred near to the Caspian Sea over 2,000 km to the East, with rapid expansions Northwards into Central Russia and Southwards into Iran/Iraq.

Could this be a sign that core R1a was mainly pushed out of Central Europe by other haplogroups, and in the cold, dry climate of the East had to travel as far as the Caspian before finding somewhere reasonably habitable?

[raspberry]

Haplogroups are not people. There is nothing more to say about this topic.

[Pip]

As with the people who carry them, haplogroups can die out, can be replaced by others, can fail to develop in an inhospitable environment and can move from one location to another.

My questions are - what are the main reasons why certain older R1a haplogroups no longer exist, why other haplogroups replaced them in the locations at which they once existed, and why other R1a haplogroups arose in locations at which they previously did not exist?