Thursday, June 4, 2015

Koreans With mtDNA C5

In published studies, mtDNA C5 (without further mutations for subclades of C5) is most common among the Paleo-Siberian Ket people near the Yenessi River, makes up about 0.1% of Koreans in published studies of Korean mtDNA, and makes up a bit larger percentage of Mongolians.

But, there are three unrelated individuals with mtDNA C5 and Korean ancestry at 23andMe (in addition to three more individuals, at least, who are related in the maternal line to one of the three).

C5c1 is found in some modern Eastern Europeans with a mutation rate based estimate of its arrival in the Neolithic era, and C5 has been found in Neolithic era mtDNA in Hungary.  But, this derived clade of mtDNA C5 is not found in East Asians.

A Hypothesis Or Two

My working hypothesis is that during the relatively brief period when Korea was under Mongolian rule during the peak of the Mongol Empire in the 13th-14th century, Male Korean aristocrats were frequently required to marry Mongolian princesses by the Mongolian Empire's regime.  The relationships are a plausible source for mtDNA C5 in Koreans, which would otherwise be much more rare.

The Y-DNA impact of Mongol expansion has been explored, for example, here (2003 source article here) but since these events happened in the historic era, we know that Korea was a historically fairly unique case in which introgression of Mongol elites into Korean society was female rather than male biased.

It may be possible to test this hypothesis using genological records.  Korea has one of the longest time series of widespread accurate genological records found anywhere in the world (particularly with elites and the "middle class" such as it was) that goes back about about 750 years to ca. 1250 CE, just long enough to capture the arrival of Mongolian brides.  It would be a painstaking, but relatively straighforward matter to identify individuals with mtDNA C5 and to trace their matriline ancestry back to this time period, although it may very well be the case that North Korean parts of these geneologies may not be available to investigators due to the near total isolation of the current North Korean state.

Another plausible source of mtDNA C5 in Koreans that could explain its rarity in published studies is that it could be more common in North Koreans than in South Koreans, since the vast majority of population genetic evidence about Korea is from North Korea.  At least one of the three 23andMe clusters is specifically North Korean in origin.  North Korea is, of course, geographically closer to the heartland of mtDNA C5 than South Korea, and equally important, more ecologically similar and hence more agreeable for bride exchange and migration based sources.

This could shed light on the existence of ejective glottal consonants in Korean and certain Japonic languages.


Ebizur said...

One way to test your hypothesis might be to check the frequency of mtDNA haplogroup C5 among Japanese people. The Mongol Empire's attempts to invade Japan were infamous failures, so if mtDNA haplogroup C5 is found in Japan with frequency greater than or equal to the frequency with which it is found in Korea, then your Mongol princess hypothesis for the origin of haplogroup C5 in Korea could reasonably be discarded.

Maju said...

Don't you think that C5 is old and widespread enough to have arrived to Korea much earlier than you suggest? Ebizur's test makes sense also.

G Horvat said...

The frequency of mtDNA haplogroup C is 7/828 in Japan. 6 of those are C1 (possibly from America). Therefore, the Japanese do not have C5.

andrew said...

Another hint supporting my Mongol Princess theory is that one of the three 23andMe mtDNA C5 clusters (the one to which my children, wife, and mother-in-law among others belong) is traced to a family that was in the highest economic elite of Korea prior to the Korean war.

23andMe caters to a non-random sample of affluent people with a disproportionate share of Western clients (with genetically Asian people often derived from recent upper class immigrants). So, it would make sense for an mtDNA clade that was disproportionately upper class in Korean to be overrepresented in 23andMe. Of course, any three event result could be just a statistical fluke, but the fact that the 23andMe sample of Koreans isn't that huge to start with is suggestive that it is bias and not just random chance.

andrew said...

Also, C5 is found at low rates in the Chinese, possibly for the same reason it is found among Koreans.

andrew said...

"The frequency of mtDNA haplogroup C is 7/828 in Japan. 6 of those are C1 (possibly from America). Therefore, the Japanese do not have C5."

I am not aware of any published instances that have found mtDNA C5 in Japan (although surely in a nation of 120,000,000 or so, there must be at least a handful). But, the C1 in Japan is very likely autochronous and not from America. There are multiple published instances to that effect and published studies generally make a concerted effort to exclude people with known non-local ancestry from their studies (usually at least to the grandparent level).

andrew said...

Also, addressing Maju's other point, C5 is certainly old enough and widespread enough that it could have another source in North Korea, for example, through an isolated instance of bride exchange in a much earlier era, and the negligible low levels of Mongolian or Yakut ancestry in the individuals that I am aware of with mtDNA C5 tends to rule out an recent source of this mtDNA haplogroup in Korea.

It has to have had a source at least about 11 generations (roughly 300 years) before present that was not supplemented later to have such a slight autosomal DNA signature (less than 0.05%).

But, that test doesn't distinguish the Mongolian princess theory from the even more ancient bride exchange theory, because the Mongolian princess theory implies a date about 800+ years ago (more than 27 generations) while the ancient bride exchange theory implies an even earlier date, neither of which would have involved sustained contact that would prevent near infinite dilution of the mtDNA C5 uber-mother's autosomal DNA.

On the other hand, the founding population of Korea has a fairly small effective population size followed by rapid population expasion during which the loss of haplogroups due to genetic drift is rare. If the introgression of mtDNA C5 happened at a time too close to Korean ethnogenesis the minimum percentage of mtDNA C5, there is a high probability that it would have either drifted out of the Korean mtDNA gene pool early on, or have been fixed at a higher percentage of the Korean mtDNA gene pool in that initial expansion process. mtDNA C5 could have been a statistical fluke that did neither and maintained an improbable but not impossible intermediate value, but the likelihood that mtDNA C5 entered the Korean mtDNA gene pool after the proportion of mtDNA haplogroups in the Korean mtDNA gene pool was close to fixation and the effective material population size of the Korean mtDNA gene pool was well in excess of 1,000, is much more likely.

Realistically, the mtDNA pool in Korea was probably fixed no earlier in Korean history than the Mumun pottery period (ca. 1500 BCE-300 BCE) when the first agricultural societies began to emerge in the region. So the introgression of mtDNA C5 in the Korean mtDNA gene pool probably took place sometime after 1500 BCE and before 1700 CE, and I would tend to favor a time period after the Korean Bronze Age ca. 700 BCE and before the end of Mongolian influence resulting in purges of Mongolians in the 1350s CE.

There were multiple Japanese invasions and occupations of Korea from 1592 to 1945, but as we've established, none of these were a likely source of mtDNA C5 because that is absent as far as we know, from Japan. The same can be said for multiple American and European colonial contacts during that time frame.

Manchu invasions in 1627 and 1636 were from a place much more likely to be a source of mtDNA C5, but both would have been very male dominated and unlike to introduce an mtDNA line into Korea.

The Joseon Dynasty's sustained policy of strict isolation of Korea from the rest of the world starting in 1392 CE and interrupted primarily only by invasions and occupations by outside powers, together with what we know about the history of those invasions and occupations, makes introgression of mtDNA C5 in the Korean mtDNA gene pool later than the period of Mongolian influence, but before the roughly 1715 CE cutoff date based upon the absence of autosomal DNA that one would expect to see together with mtDNA C5, unlikely.

andrew said...

Another time when conditions would have been favorable for the introgression of mtDNA C5 into Korea, possibly with a Northern geographic bias within Korea, would have been during the Goguryeo Kingdom which "reached its zenith in the 5th century [CE], when King Gwanggaeto the Great and his son, King Jangsu, expanded the country into almost all of Manchuria and part of inner Mongolia, and took the present-day Seoul from Baekje." This kingdom fell in the face of invasions from its neighbors to the South, temporarily united, around 668 CE.

The Gojoseon Kingdom has a similar extent around 500 BCE, and ultimately collapsed around 108 BCE giving rise to the proto-Three Kingdoms era of Korean history.

andrew said...

An open access 2010 paper at PLOS looks quite rigorously at genetic evidence for migration between Korea and its neighbors. The paper notes the SE Korea has historical links to Siberia:

"Geographically, the Korean Peninsula is a strategic location in East Asia surrounded by China, Japan and Russia. Therefore, the objectives of our gene flow analyses in Northern, Eastern and Southern Asia were to determine the extent of the gene flow from these neighboring countries and the levels of genetic signals that have remained in the Korean Peninsula, using subjects collected from the ten most historical regions in South Korea.

In addition, samples from Mongolia, Jinlin in China and Amerindian populations, representing Northern people; Cambodians and Vietnamese, representing Southern people; and Chinese and Japanese were used to measure their influences on the gene flow. For this study, we propose three different gene flow models based on historical events, geographical location and anthropology;

Model I: SW (South West) Korea, which includes the JJ, NJ and GJ regions (Fig. 1) has some lineages in common with the BaekJae Empire (BC18-AD660) through a migration event by the Northern people of the Goguryeo Empire which ruled most of Northern Manchuria and Korean peninsula (BC37-AD568), and are also closely related to Mongolians. They ruled most of the Eastern part of China and most of the South Western part of the Korean Peninsula.

Model II: SE (South East) Korea, which includes the GU, US and GR populations (Fig. 1), is the region where the Northern people from Siberia (based on their grave patterns and ancient cultural traditions) and the loyal Southern families were settled in the Shilla(BC57-AD918) and Kaya(AD42-532) Empires, respectively.

Model III: MW (Middle West) Korea, which includes the YC, JC, CA and PC populations (Fig. 1), is the human melting pot of the Korean Peninsula where Western Chinese, including those from the SanDung Peninsula, crossed the Yellow Sea between China and Korea, living and trading in both regions. In addition, it is known that historically the Northern and Southern Koreans often clashed with each other in this region."