Myanmar, also known as Burma, has been one of those blind spots in the mapping of human genetics. Finally now we get to know something about the peoples of this SE Asian multiethnic state, although there are limitations because the sampling was performed among refugees in Thailand.
Monica Summerer et al., Large-scale mitochondrial DNA analysis in Southeast Asia reveals evolutionary effects of cultural isolation in the multi-ethnic population of Myanmar. BMC Evolutionary Biology 2014. Open access → LINK [doi:10.1186/1471-2148-14-17]
Myanmar is the largest country in mainland Southeast Asia with a population of 55 million people subdivided into more than 100 ethnic groups. Ruled by changing kingdoms and dynasties and lying on the trade route between India and China, Myanmar was influenced by numerous cultures. Since its independence from British occupation, tensions between the ruling Bamar and ethnic minorities increased.
Our aim was to search for genetic footprints of Myanmar’s geographic, historic and sociocultural characteristics and to contribute to the picture of human colonization by describing and dating of new mitochondrial DNA (mtDNA) haplogroups. Therefore, we sequenced the mtDNA control region of 327 unrelated donors and the complete mitochondrial genome of 44 selected individuals according to highest quality standards.
Phylogenetic analyses of the entire mtDNA genomes uncovered eight new haplogroups and three unclassified basal M-lineages. The multi-ethnic population and the complex history of Myanmar were reflected in its mtDNA heterogeneity. Population genetic analyses of Burmese control region sequences combined with population data from neighboring countries revealed that the Myanmar haplogroup distribution showed a typical Southeast Asian pattern, but also Northeast Asian and Indian influences. The population structure of the extraordinarily diverse Bamar differed from that of the Karen people who displayed signs of genetic isolation. Migration analyses indicated a considerable genetic exchange with an overall positive migration balance from Myanmar to neighboring countries. Age estimates of the newly described haplogroups point to the existence of evolutionary windows where climatic and cultural changes gave rise to mitochondrial haplogroup diversification in Asia.
The main sampled ethnic group are the Karen, who live at the border with Thailand, but the Bamar or Burmans, the largest ethnic group, were also sampled in big numbers.
|Fig. 2.- Origin of samples and mitochondrial haplogroup distribution of Southeast Asian populations. Although most of the study participants originated from Karen State (red), a broad
sample spectrum from nearly all divisions and states of Myanmar (a) was included in this study. b shows the haplogroup distributions of populations from Myanmar and four other Southeast
Asian regions. In the white insert box the haplogroup heterogeneity of two ethnic
groups of Myanmar is illustrated. The hatched area in the map surrounding the border
between Myanmar and Thailand shows the main population area of the Karen people. The
Bamar represent the largest ethnic group (68%) in Myanmar. The size of the pie diagrams
corresponds to sample size.
The smaller samples are only detailed in the supplementary data for what I have seen, so I will not discuss them right now (maybe in an update?).
Overall all SE Asians including the Southern Han from Hong-Kong appear similar in broad terms. Excepted Laos, this relative similitude is quite apparent in figure 3:
|Fig. 3.- Multi-dimensional scaling plot of pairwise Fst-values and haplogroup distribution
of populations from Myanmar and 12 other Asian regions. A distinct geographic pattern appeared in the multi-dimensional scaling plot (Stress = 0.086;
R2 = 0.970) of pairwise Fst-values: The Myanmar sample fitted very well within the Southeast
Asian cluster, the Central Asian populations formed a second cluster, the Korean sample
represented East Asia, the Afghanistan population was representative for South Asia
and Russia symbolized Western Eurasia. The main haplogroup distributions are displayed
as pie charts. The size of the pie diagrams corresponds to sample size. The proportion
of N-lineages (without A,B and R9’F) increases from very low percentages in Southeast
and East Asia over 50% in Central Asia to more than 75% in Afghanistan and 100% in
the sample of Russian origin. The proportion of the American founding haplogroups
A,B,C and D displayed an interesting pattern: from inexistent in Russians it increased
to more than 50% in East Asian Korea.
Looking at the particular differences in haplogroup frequencies, I’d say that the Thai are quite unremarkable, while the other populations show some peculiarities:
- Karen: higher frequencies of R9/F, A, C and G
- Bamar: much higher M* (and extremely diverse)
- Laotian: higher frequencies of B and M7
- Vietnamese: more B and N*
- South Han (Hong-Kong): more D
It is very notable the high diversity of paragroup M* among the Bamar. The authors notice that not more than three individuals shared each different subhaplogroup, what points to a very high diversity within haplogroup M. I don’t have time right now to ponder the various lineages, some of which are newly described, but I probably will in the future, because, together with the high diversity in NE India, they have the potential of shifting the paradigm of Asian colonization by H. sapiens a bit towards the East.
The various M* and other novel haplogroups described in Myanmar is shown in fig. 4
. Haplogroups M90 and M91 are new basal M sublineages, along with three other unnamed private lineages, which also appear as basal. Also M20a, M49a and G2b1a are new sublineages further downstream. Within N/R, another newly described lineage is B6a1.
The Bamar are extremely diverse not just within M*:
… the haplogroup composition of Bamar
was exceptionally diverse with 80 different haplogroups and a maximum of 6 samples
in the same haplogroup (Figure 4).
On the other hand, the Karen show the signs of genetic isolation instead, with large concentrations in the same haplogroups.
Interestingly, the authors think that rather than being a receiver, Myanmar was a major source of population to its neighbors:
Migration analyses of Myanmar and four Southeast Asian regions displayed a vivid exchange
of genetic material between the countries and demonstrated a strong outwards migration
of Myanmar to all analyzed neighboring regions (for details see Additional file 4: Table S4).
This influence is most intense to Laos, Thailand and South China, while things are more balanced regarding Vietnam instead.