Note: This page currently contains only a stub. I will revisit and more fully research it when time permits and there is more information to research.
This is a one of a set of essays tracing peoples with my specific paleo-European kinship from their origins in Africa ~70ka to their destination in England in the current era. This chapter attempts to deduce the location of the various clades of NRY Haplogroup I-M170 during the Last Glacial Maximum (LGM), the coldest part of the last European glaciation. This COLD period lasted ~13k years. Thus we examine here the period 27ka to 15ka.
For motivation, technical background, and links to all chapters, refer to the Preface.
By 26.5ka, the northern hemisphere glaciation was at its maximum advance and remained there for about 7ky, a long time on a human time scale. Human life in Europe north of the Alps would have been very difficult. Starting around 19.5ka, there was a gradual warming for around 5ky, but it was still a very harsh environment in northern Europe.
Around 14.8ka, there occurred a very rapid increase in temperatures that provided 2000 years of relief from the long glaciation. This warm period very suddenly terminated around 12.8ka in a new Big Freeze, the Younger Dryas cooling event that lasted 1,300 years. When this cold event ended ~11.5ka, the Holocene began with a continual warming that has been stable to the present, excepting for some minor cooling periods.
The decline and collapse of European megafauna occurred just prior to the start of the Holocene, including extinction of woolly mammoth, woolly rhinoceris, bison, cave lion, and panthers/leopards. Auroch and horse populations crashed as well, but a small population survived. Some theories have the Younger Dryas Big Freeze (12.85ka-11.57ka) as a principal cause. Others have human hunting skills leading to an overkill. Megafauna collapses have been observed on all continents. There is weak statistical correlation with known climate events and these collapses. There is a better correlation between human activity and technology advances and these collapses.
Also, researchers are still looking for clues to the dramatically quick commencement of the Younger Dryas climate cooling and, after 1,300 years, re-warming. These events took less than a decade each, perhaps only a year or two. Such climate flips, without warning, would spell great hardship for humanity going forward, so understanding them is a priority. A theory for this event is the cessation of thermohaline current in the Atlantic due to freshwater melt.
At the end of the LGM, there is evidence of a gigantic glacial melt lake, Lake Agassiz, 700 miles wide spanning the US-Canada border in central North America. At its maximum it is thought to have contained more water than the Caspian Sea. There have been many attempts to link outflows from Lake Agassiz to the Younger Dryas climate event.
There may have been small releases down the Mississippi, and into the Great Lakes, but they left little evidence and the timing and quantity didn’t match known climate events. Evidence of one final outflow into Hudson Bay perhaps matches the timing of the cooling period that began 8.2ka. Just recently, a new paper claims to document a mega-flood to the north toward the Mackenzie River delta, then discharging into the Arctic Ocean, from which it made its way to the North Atlantic. The flood event has been dated to roughly 13ka, so the cause of the Younger Dryas may have been resolved.
Alternatively, a scenario projecting collision between Earth and a comet had been rejected based on misinterpretation of evidence, but it recurs with publishing of new papers that mention evidence of global firestorms at commencement, such as might be produced by collision with a large, fragmented comet fireball.
Regardless of cause of the megafauna collapse, the epipaleolithic occupants of Europe lost a major source of nutrition, the boreal environment lost a source of intervention and variation from grazing animals, and the atmosphere lost a source of methane.
Last Glacial Maximum (LGM) Refugia
The 10k years following the start of the LGM period presented harsh living conditions during which populations were small and male lineage extinction rates were close to 1. A haplogroup I researcher estimates only a very few males living 13ka, probably fewer than 10, are the fathers of all today’s millions of I people.
The eastern I-M170 probably sequestered in the Balkans and Carpathian Basin; possibly some also mingled with the R1a peoples north of the Black Sea. Any western I-M170 (there may not have been any) would have sequestered from Italy through southern France to the Pyrenees. If there were no western I-M170 people, then the IJ-M429 people may have been responsible for the Solutrean tool kit found across southern France, a successor to Gravettian. The eastern I-M170 people retained the Gravettian technology, eventually morphing into Epigravettian.
The divergence of the I1 and I2 clades has been estimated to have been ~28ka, nearly simultaneous to the appearance of I-M170. Their history during the LGM period is largely conjecture.
One thinks of I1-M253 as the Norse clade, because its current center of residence is Fennoscandia. But SNP M253 is phylogenetically equivalent to several other binary polymorphisms in the I1 ancestry (23 by ISOGG count in 2011), potentially spread over more than 20k years.
All current I1 males have an MRCA that lived relatively recently, two current estimates being 4.5ka and 8.1ka. Although I1 was the earliest clade to split from the I-M170 parent population, the estimate of a recent MRCA of all current I1 people would signify that any region of I1 descendants today arrived there probably much less than 8ka. So all evidence of their early movements has been erased from the genetic history of the current populations.
The MRCA of the current I1 population likely lived in southern Scandinavia, and his descendants spread out from there beginning in the Neolithic. Because of the gaping hole in I1 genetic expansion, one can say hardly anything definitive about them in the LGM period except that they were in Europe somewhere.
Because of this difficulty, and because I am I2, the remainder of these essays deal with I2. One conjecture is that the I1 and I2 peoples were long associated in geographic distribution, although the only fact I know that might support this is that they both ended up in the vicinity of the North Sea together. I1 and I2 still show combined high density in southern Sweden, Denmark, and northern Germany.
At 17ka, the MRCA of all I2 people living today originated within the I2 population while in their presumed Carpathian/Balkan refuge. This was just before populations began to re-enter central Europe, following the retreating ice sheet. The absence of significant I2 presence in southern France corroborates that the I2 ancestors probably waited out the LGM in southeast Europe.
There is a remnant of the I2* clade, divided into three populations. I2*-A is found in the extreme northwest of Europe, in Scotland and Ireland. I2*-C is found beyond the extreme of southeast of Europe, in the area of Armenia and eastern Anatolia. I2*-B is found in central Europe. Perhaps the A and C subclades mark the extremes of the range of the I2 people after the repopulating of Europe, while some of the most dense central population also still survives.
Corresponding to the megafauna collapse, there appeared a new branch of I2 marked by L460, which in turn quickly bifurcated into the two principal subclades of I2 in our continuing story.
I2-P37.2: Around 21ka, the the P37.2 clade originated within the I2 population, probably in the Balkans. This population remained in the Mediterranean area, in the Balkans and Italy, and spreading along the Mediterranean coast to the Iberian peninsula. Their greatest population concentration today is in the Balkans and on the island of Sardinia. Because I2-P37.2 did not spread north of the Alps in central Europe in any early group migrations, it is thus not part of our continuing story.
I2-M436: Around 14ka, the early I2 expansions back into Europe were impacted by the sudden Younger Dryas cold period, which lasted for another 1.3k years. During this Big Freeze, the I2-M436 people originated within the I2 population, possibly along the Danube in the Carpathian Basin. The eventual center of their populations would be north Germany.
The I2-M436 people had advanced to an epigravettian toolkit when they began their expansion into Germany, perhaps traveling up the Danube to the Elbe and the Rhine north toward the North Sea, as their IJ* ancestors had done over 25ka prior. The path of expansion of the I2-M436 peoples will remain conjecture, however, because there appear to be no current living members of I2-M436*. All I2-M436 members today are found in subclades I2-M223 and I2-L38, in central and north Germany.
I2-M223 and I2-L38 Peoples
The I2-M223 SNP first appeared on the North Sea coast around 9ka, and around the same time the I2-L38 clade first appeared in north central Germany. A female U5b clan may have traveled with them.
A recent discovery in Lichtenstein Cave near Göttingen offers DNA evidence from around 1000BCE, associated with the bronze age Urnfield Culture. 12/19 males were I2-L38, and there were 6 U5b results from mtDNA. While there was no apparent I2-M223, there was also only a minor component of R1a and R1b, perhaps confirming the main R1a advance had stopped short of the Oder and the R1b advance had remained in the southern sub-alpine areas of Germany during the second millennium BCE.
We next follow the I2-M223 clade in its development along the current Denmark-Germany border and the coast of the North Sea though the European Holocene Prior to Neolithic.