I was very pleased to see the article, “Does Mitochondrial Haplogroup X Indicate Ancient Trans-Atlantic Migration to the Americas? A Critical Re-Evaluation” by Jennifer Raff and Deborah Bolnick.
This is one of those topics that gets brought up over and over again and is often presented in the form of an urban legend with some level of bias based up on the agenda, exuberance or opinion of the person who is presenting the evidence. In other words, it makes for good click-bait.
Personally, I don’t have a horse in this race. I care about the truth, whatever it is, being discovered and unraveled. I think the authors of this paper have done a good job of presenting the evidence in both directions then drawing conclusions based on scientific data as we know it. There has been new evidence emerge in the recent past and there is likely to be more in the future which, depending on the evidence, could cause a re-evaluation of this topic.
Why has haplogroup X2 been so contentious and controversial when the other Native American haplogroups have not?
There are two primary reasons:
- There is no clear-cut genetic path across Beringia to the New World for X2a, meaning that X2a is not found in Siberia in the areas bordering Beringia. The ancestral form of the other Native American haplogroups are found there, indicating a clear migration path. Having said that, haplogroup X2a and subgroups is very clearly the rarest of the Native American mitochondrial DNA haplogroups and it’s certainly feasible that not enough testing has been performed on living or ancestral people to discover X2 or X2a directly ancestral individuals. It is also possible that line has died out, but hopefully we will still find examples in skeletal remains as more are DNA typed.
- Many of the early carriers of haplogroup X2a were found in eastern maritime Canada, a prime theoretical landing location for Solutreans. This certainly fanned the Solutrean flame. However, more recent discoveries of haplogroup X2a and subgroups have been more widely geographically dispersed. Neither is there a path or ancestral form of X2a found in Europe or the Middle East.
Looking at the X2a subgroups (X2a, X2a1, X2a1a, X2a1b, X2a1c, plus three forms of X2a2) in the haplogroup X project at Family Tree DNA, the American Indian project, GenBank and various academic papers, we find the following locations identified for X2a and subgroups, moving west to east:
- Pasadena, California
- Chihuahua, Mexico
- Edmonton, Alberta
- Selkirk, Manitoba
- Manitoba (2)
- La Pointe, Wisconsin
- Ontario border with Michgan (Manitoulin Island)
- St. Ignace, Michigan (near border with Ontario)
- Manawan, Quebec
- Newfoundland and Labrador
- Newfoundland (Island) 2
- Cape Breton, Canada
- Nova Scotia, Canada
Although not in the haplogroup X project, X2a2 has also been found among the Navajo and Jemez in the American Southwest and in Kennewick Man found in Kennewick, Washington. Other tribal affiliations include the Chippewa, Ojibwa and Sioux. Given the Newfoundland and Canadian seaboard locations, the Algonquian speaking Micmac and Beothuk populations would clearly be involved as well.
Note on the X2a map above reflecting the oldest known ancestral locations, that no locations appear outside of North America.
Haplogroup X2a is believed to have developed in Beringia during the period of isolation of approximately 8,000 years experienced by the people who were to become the “First Nations” and “Native Americans” in North America. This is the reason, not just for X2a, but for other haplogroups as well, that some subgroups exist only in Native people in the New World and not in Asia from whence they came. Those haplogroup identifying mutations occurred during their long stay in Beringia.
We know from archaeological excavations along with genetic analysis in some cases that the Native people by roughly 14,000 years ago had emerged from Beringia, trekked southward and were in Monte Verde in Chile. The Native population seems to have diverged into two groups, one in South America who likely arrived via a western coastal route, and one who migrated more eastwardly, the ancestors of Anzick Child who lived about 12,500 years ago in Montana and whose DNA has been tested.
Kennewick Man who carries the oldest form of haplogroup X2a yet found in the Americas was dated to be about 9,000 years old and was found in Washington State, so clearly X2a was present in the Native population 9,000 years ago and on the western side of the continent.
You will note that in the list of X2a results given above, none of the locations are any further south than Chichuhua, Mexico. Based on the locations of these most distant ancestors, a primary west to east migration path just north of the present day border between the US and Canada is suggested, along with a secondary path southward along the Pacific coast or western corridor.
Here are the salient points listed by Raff and Bolnick in support of haplogroup X2a and subgroups originating in Asia, along with the other Native American haplogroups, and arriving together in the same settlement wave:
- Haplogroup X2a is present in the Americas in pre-European contact skeletal remains confirming is it not a result of post-contact admixture.
- While the Altai, considered to be the original Asian homeland of today’s Native American people, do carry haplogroup X2, the linking mutations between X2 and X2a have not been found in that or any other population group today. Haplogroup X itself originated in the Middle East before X2 evolved, but that is not indicative of Hebrew or European ancestry.
- X2a is not found in the Middle East, and therefore could not have been part of a theoretical Hebrew migration from the Middle East 2500 years ago. Haplogroup X2a was found in Kennewick man who lived 9000 years ago, in Washington State, so X2a in the Americas predates the proposed Hebrew migration by some 6,500 years.
- The oldest and deepest rooted X2a result, relative to the haplotree, is Kennewick man whose remains were found in the western US. If X2a was the result of a Solutrean migration during the Pleistocene 23,500 to 18,000 years ago with a landing base in Newfoundland or someplace on the east coast, the oldest and deepest lineages should be found in the eastern population, not on the west coast.
- Based on coalescence dates and demographic history, X2a is likely to have originated in the same population as the other American founder haplogroups.
- Kennewick Man was explicitly tested for his affinity with European and Polynesian populations and that hypothesis was rejected.
- Studies have indicated that a population found in central Asia contributed strongly to both the Native American population and the European population by moving from central Asia into both Europe and Siberia, but that does not equate to Europeans being ancestral to Native Americans. Instead, a common ancestral population often referred to as the “ghost population” was part of the founding group of both Europeans and Native Americans as described here and here. This means that later European populations, such as Germanic people who do show small amounts of “Native American” admixture are probably more closely related to Native Americans than earlier populations from before the central Asian people arrived and settled en masse in Europe.
- No Solutrean skeletal remains have been recovered in Europe in order to facilitate a direct comparison. However, if Solutrean people did arrive in the New World on the east coast, one would not expect to find a European/Solutrean signature equally distributed among all native people, but instead distributed in a gradient pattern with the highest levels closest to where the Solutrean people lived, meaning their landing point. In other words, it would radiate outward like ripples from a rock thrown into water. However, the genetic signature of West Eurasian ancestry in Native American people is found equally in all Native American genomes tested to date, and as such, predates the evolution of regional genetic structure within North and South America as reflected in migration patterns.