Content uploaded by Elena Gigli
Author content
All content in this area was uploaded by Elena Gigli
Content may be subject to copyright.
Tracing the Origin of the East-West Population
Admixture in the Altai Region (Central Asia)
Mercedes Gonza
´lez-Ruiz
1
, Cristina Santos
1
, Xavier Jordana
2
, Marc Simo
´n
1
, Carles Lalueza-Fox
3
,
Elena Gigli
3
, Maria Pilar Aluja
1
, Assumpcio
´Malgosa
1
*
1Unitat d’Antropologia Biolo
`gica, Dept. BABVE, Universitat Auto
`noma de Barcelona, Bellaterra, Barcelona, Spain, 2Institut Catala
`de Paleontologia Miquel Crusafont (ICP),
Universitat Auto
`noma de Barcelona, Bellaterra, Barcelona, Spain, 3Institut de Biologia Evolutiva, CSIC-UPF, Barcelona, Spain
Abstract
A recent discovery of Iron Age burials (Pazyryk culture) in the Altai Mountains of Mongolia may shed light on the mode and
tempo of the generation of the current genetic east-west population admixture in Central Asia. Studies on ancient
mitochondrial DNA of this region suggest that the Altai Mountains played the role of a geographical barrier between West
and East Eurasian lineages until the beginning of the Iron Age. After the 7th century BC, coinciding with Scythian expansion
across the Eurasian steppes, a gradual influx of East Eurasian sequences in Western steppes is detected. However, the
underlying events behind the genetic admixture in Altai during the Iron Age are still unresolved: 1) whether it was a result of
migratory events (eastward firstly, westward secondly), or 2) whether it was a result of a local demographic expansion in a
‘contact zone’ between European and East Asian people. In the present work, we analyzed the mitochondrial DNA lineages
in human remains from Bronze and Iron Age burials of Mongolian Altai. Here we present support to the hypothesis that the
gene pool of Iron Age inhabitants of Mongolian Altai was similar to that of western Iron Age Altaians (Russia and
Kazakhstan). Thus, this people not only shared the same culture (Pazyryk), but also shared the same genetic east-west
population admixture. In turn, Pazyryks appear to have a similar gene pool that current Altaians. Our results further show
that Iron Age Altaians displayed mitochondrial lineages already present around Altai region before the Iron Age. This would
provide support for a demographic expansion of local people of Altai instead of westward or eastward migratory events, as
the demographic event behind the high population genetic admixture and diversity in Central Asia.
Citation: Gonza
´lez-Ruiz M, Santos C, Jordana X, Simo
´n M, Lalueza-Fox C, et al. (2012) Tracing the Origin of the East-West Population Admixture in the Altai Region
(Central Asia). PLoS ONE 7(11): e48904. doi:10.1371/journal.pone.0048904
Editor: David Caramelli, University of Florence, Italy
Received July 17, 2012; Accepted October 2, 2012; Published November 9, 2012
Copyright: ß2012 Gonza
´lez-Ruiz et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors acknowledge the following grants: Generalitat de Catalunya: SRG 2009- 566; European Union, INTERREG III: I3A-10-319-E; Ministerio de
Economı
´a y Competitividad, Gobierno de Espan
˜a, Programa Juan de la Cierva: JCI-2010-08157. The funders had no role in study design, data collection and
analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: Assumpcio.Malgosa@uab.cat
Introduction
Historically, Central Asia has been a crossroad between West
and East Eurasian people leading to the current high population
genetic admixture and diversity. The origin of this diversity may
go back as early as the Iron Age, more than two thousand years
ago, with the dispersal of mounted pastoral nomads across the
Eurasian steppes [1,2,3]. The present study deals with early
contacts between West and East Eurasian populations and
specifically those that occurred in the Altai region (Central Asia).
Because the Altai Mountains represent a natural boundary
between West and East Eurasian steppes, this region is key to
understanding demographic events in the steppes of Central Asia.
Archaeological work conducted by a Spanish–French–Mongo-
lian team in the Mongolian Altai during the period 2005–2007
discovered burial sites belonging to the Pazyryk culture. This was
the first time that this culture was found in Mongolia [4,5] Pazyryk
is the name given to Iron Age nomadic tribes who inhabited the
high steppes of the Altai Mountains between the fifth and third
centuries BC. This culture is known from the discoveries of stone
tumuli holding frozen bodies of warriors buried with their horses
and their weapons [6,7]. Pazyryk culture sites were first described
in the Altai region of South Siberia and East Kazakhstan
[6,7,8,9,10]. More recently, two different expeditions [5,11] also
discovered Pazyryk burials in the Mongolian Altai, indicating that
this Iron Age people had also spread into East Asia (Fig. 1).
The Pazyryks have traditionally been associated with the
Eastern Scythians. Scythians, whose history is well-known from
the ancient texts of Herodotus (484–425 BC), was the name that
the Greeks gave to a number of separate Indo-European-speaking
nomadic groups living in the region encompassing the Pontic-
Caspian steppe (in Eastern Europe) and the steppe of Central Asia.
The Scythian culture (7th-2nd century BC) flourished in this
region from local Indo-European peoples that emerged at the
Pontic-Caspian steppe in about 2000BC and expanded eastward
until they reached the Altai Mountains. Advances in technology
that favoured mounted nomadic pastoralism were the triggers for
the expansion of Scythian culture across the Western Eurasian
steppe. The end of Scythian period might be related with the
westward migrations of nomadic Turkomongolian tribes coming
from East Asia since the 3rd century BC, which marked the end of
Indo-European domination of the steppe [12,13,14,15].
Archaeological findings, almost entirely provided by burial site
discoveries, documented that the Scythians had European
morphological features [7,8,12]. However, several recent works
PLOS ONE | www.plosone.org 1 November 2012 | Volume 7 | Issue 11 | e48904
focusing on ancient mitochondrial DNA (mtDNA) of Eastern
Scythian burials [9,10,11,16,17,18,19] revealed that this popula-
tion has a mixed mtDNA composition of West and East Eurasian
lineages. This is particularly interesting for the timing of the early
contacts between European and Asian people in Altai because all
ancient DNA samples analysed so far from Central Asia belonging
to a period before the Iron Age bore West Eurasian lineages
[18,20].
These molecular data raise two likely hypotheses for the origin
of the genetic diversity and admixture among the Iron Age
inhabitants of the Altai: 1) people holding west Eurasian lineages
arrived at Altai Mountains with the eastward migration of
Scythians and, once settled, they began to establish relationships
with the neighbouring communities from East Asia holding East
Eurasian lineages; 2) this was the result of the admixture between
the native people inhabiting either sides of the Altai Mountains
(people with West Eurasian lineages in Western Altai and East
Eurasian lineages in the Eastern Altai), as a result of a
demographic expansion during the Scythian period. Hence, the
second hypothesis would provide support to the cultural transmis-
sion against the demic diffusion during the Scythian period.
The skeletal remains unearthed by our team from Bronze and
Iron Age tumuli in the Mongolian Altai offer a unique opportunity
to get further insights into the ancient Altaians. Here, we aim to
shed light on the origin of the current east-west population
admixture in Central Asia, specifically in the Altai region, by
analyzing the mitochondrial DNA lineages of these skeletons.
Owing to the clear geographical structuring of the East and West
Eurasian lineages in Central Asia population, mtDNA is
particularly suited for the study of admixture in this region [18].
This study may contribute to providing early evidence of
population admixture between European and East Asian people,
as well as the underlying causes behind this demographic event in
the Eurasian steppes.
Materials and Methods
Samples and DNA Extraction
Skeletal remains from 19 individuals of Bronze and Iron Age
[5] were retrieved from four archaeological sites located in
Bayan-O
¨lgiy province (Mongolia, Altai) (Fig. 1, Table 1). For
the nineteen exhumed individuals, teeth and bone samples were
taken in the field by one of us (XJ) following sterility criteria
and were stored in cold conditions. Afterwards, samples were
taken to the laboratory dedicated to paleogenetic studies at the
Universitat Auto`noma de Barcelona where they were processed.
Independent replications were performed at the Institut de
Biologia Evolutiva (CSIC-UPF).
For DNA extraction, 0.1 g of powder was extracted from teeth
pulp cavities; when bones were used, 0.5 g of powder was collected
from the internal compact tissue. After DNA treatment and
extraction (as described in [21]), purification of the samples was
performed with a JetQuick PCR Purification kit (Genomed Lo¨hne,
Germany) to remove any possible inhibitors that the samples
might carry and it was stored at 4uC [22].
Mitochondrial DNA Analysis
For each sample, the mtDNA hypervariable region I (HVRI)
was amplified and sequenced, and coding region informative
polymorphisms for haplogroup assignment were analysed by
PCR-RFLPs. The PCR reactions were carried out in a final
volume of 50 ml and Taq polymerase (BiolineH) was used. Each
PCR reaction consisted of an initial denaturation step (5 min at
94uC) followed by 39 cycles of PCR (50 s at 94uC, 1 min at
annealing temperature depending on the region to be amplified,
and 1 min at 72uC) and a final extension step of 5 min at 72uC, or
of 10 min if the amplified segment was to be cloned. Amplified
fragments were then visualized with Ethidium Bromide staining in
a 3% agarose gel [23]. To analyse the HVRI, four overlapping
fragments were used (Table S1). These were subsequently
sequenced and cloned. Sequence reactions were carried out using
the sequencing kit BigDye Terminator v.3.1 (Applied Biosystems,
Carslbad, USA) according to the manufacturer’s specifications and
run in an ABI 3130XL sequencer.
For all samples, the fragment containing the majority of HVRI
mutations was cloned using the Topo TA CloningHkit (Invitrogen,
Carslbad, USA) following the manufacturer’s instructions. The
colonies were harvested and subjected to PCR with M13 universal
primers; for each sample 10 inserts of the right size were
subsequently sequenced.
For coding region analysis 10 coding region segments,
determining the 10 Eurasian haplogroups, were analysed by
PCR-RFLPs. Restriction sites and the primers used to amplify
each specific fragment of the coding region are shown in Table S1.
Figure 1. Pazyryk burials from the Altai Mountains. A. Geographical location of Pazyryk culture sites in the Altai regions of South Siberia,
Kazakhstan and Western Mongolia. B. Pazyryk burial from Baga Turgen Gol site, Bayan-O
¨lgiy province, Western Mongolia.
doi:10.1371/journal.pone.0048904.g001
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 2 November 2012 | Volume 7 | Issue 11 | e48904
Sex Determination
For genetic sex determination, X and Y Amelogenin loci and
the SRY gene (sex-determining region Y gene) were analyzed
using primers and conditions described respectively by Beraud-
Colomb et al. [24] and Santos et al. [25].
Authentication of Results
Independent replication for four teeth and one bone were
performed at the Institut de Biologia Evolutiva (CSIC-UPF) using
the methodology previously described by Lalueza-Fox et al. [26].
Moreover, to authenticate the results, the recommended criteria
concerning sterility, reproducibility, cloning, characterization of
the investigators’ haplotype, coincidence of associated markers and
diversity of the results were fulfilled. An integrative approach for
human population studies was used, where the flexibility and the
intelligent use of authentication criteria was applied [27,28,29].
Data Analysis
Sequence raw data was analysed with Sequence Scanner v1.0
(Applied BioSystems) program and sequences were subsequently
aligned with BioEdit software version 7.0.0 [30] in relation to the
revised Cambridge Reference Sequence [31]. Samples were
assigned to haplogroups using the combined information of HVRI
and coding region variation following the phylogenetic classifica-
tion updated by [32].
Haplogroups were clustered according to their geographic
origin following [33,34,35]:
a) West Eurasian haplogroups: R0: R0a’b, HV; N1; JT; UK; W
and X.
b) East Eurasian haplogroups: M: C, D, G, Z, M9, M10, M11,
M13; A; B; F and N9a.
c) South Asian haplogroups: M*, U2a-c, U9, R*, R1–R2, R5–
R6, N1d.
For comparative purposes, mtDNA sequences between posi-
tions 16051 and 16400, from ancient
[10,11,18,19,20,36,37,38,39,40] and modern populations
[3,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57] of East-
ern and Central Asia, were collected (See Table S2, for population
codes and details about period, sample size and references).
For each population, the number of different haplotypes (K),
the number of polymorphic sites (S) [58], the gene diversity
(H
ˆ) [59] and the nucleotide diversity (p) [58,59] were estimated
using the software Arlequı
´n ver. 3.11 [60].
Slatkin’s linearized FST pairwise genetic distance matrices
between population [61] were calculated using the software
Arlequin ver. 3.11. Multidimensional scaling.
(MDS) was used to represent genetic distances in a two-
dimensional space using SPSS ver. 17.0 (SPSS Inc.).
Phylogenetic networks [62] among haplotypes were constructed
using the program Network 4.610 (www.fluxus-engineering.com).
Positions of HVRI were weighted according to their site-specific
mutation rate following the weight scheme proposed by [63].
Spatial frequency distribution maps of East Eurasian lineages in
Pre-Iron Age and Iron Age periods were obtained using Surfer
version 8.05 (Golden Software).
Table 1. Sample distribution by Mongolian Altai sites and period.
Sex
Period Site Individual Age Morphological Amelogenin SRY
Bronze Age Alag Erdene AE05.T2 Adult IND =NR
AE05.T3 Adult IND =NR
Tsengel Khairkhan TSA07.T4 Adult ===
Iron Age, Pazyryk Culture Baga Turgen Gol BTG05.T1 Adult IND NR NR
BTG05.T2 Adult IND =NR
BTG05.T8.1 Adult ==NR
BTG05.T8.2 Adult RRNR
BTG05.T8.3 Subadult IND NR NR
BTG06.T3 Adult ==NR
BTG06.T8 Adult =NR NR
BTG06.T10A Subadult IND ==
BTG06.T10B Adult R=NR
BTG06.T11A Adult ==NR
BTG06.T11B Adult =NR NR
BTG06.T12 Adult ==NR
BTG06.T13 Adult =R=
Tsengel Khairkhan TSK07.T1 Adult ==NR
TSK07.T2A Subadult IND NR NR
TSK07. T2B Adult ===
IND- Indeterminate.
NR- No results.
doi:10.1371/journal.pone.0048904.t001
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 3 November 2012 | Volume 7 | Issue 11 | e48904
Table 2. Results of HVRI sequencing and PCR-RFLP of coding region informative polymorphisms.
Sequence HVRI PCR-RFLPs
Sample
16051–
16400
Haplogroup
HVRI
Hae III
+
663
Hind II
2
13259
Alu I
2
5176
Hae II
+
4830
Nla III
2
4577
Bst 0I
2
13704
Alu I
2
7025
Hae II
2
9052
Hinf I
+
12308
Alu I
+
15606
Haplogroup
PCR-RFLPs
Bronze AE05.T2 223, 292, 362 D 2+2D
AE05.T3 192, 223, 295, 362 D 2+2D
TSA07.T4* 092, 223, 311, 362 D 2D
Iron BTG05.T1 223, 319, 362 D 2+2D
BTG05.T2 093, 224, 311, 319 K 2++ 22+K
BTG05.T8.1 129, 256, 270, 304, 399 U5a1 + + U
BTG05.T8.2 223, 298, 327 C 2+C
BTG05.T8.3** 223, 239, 243, 319, 362 D
BTG06.T3 069, 126 J +22J
BTG06.T8* 223, 239, 243, 319, 362 D 22 D
BTG06.T10A 172, 311 HV6 2++++ HV
BTG06.T10B 223, 274, 311, 362 D 2D
BTG06.T11A 093, 224, 311, 319 K 222+K
BTG06.T11B* 093, 224, 311, 319 K 22+K
BTG06.T12 192, 256, 270, 304, 399 U5a1 +U
BTG06.T13 093, 129, 223, 298, 327, 362 C 2C
TSK07.T1* 093, 223, 242, 278, 290,
311, 319
A++ A
TSK07.T2A 223, 227, 278, 362 G2a ++ 2G
TSK07.T2B 126, 163, 186, 189, 294 T1 +2T
*Samples replicated in Institut de Biologia Evolutiva.
**Sample amplified in Institut de Biologia Evolutiva.
Haplogroup attribution based on HVRI and in PCR-RFLPs are also presented for each sample. Variant positions from HVRI are shown between 16051 to 16400 minus 16000.
doi:10.1371/journal.pone.0048904.t002
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 4 November 2012 | Volume 7 | Issue 11 | e48904
Figure 2. Spatial frequency distribution maps of East Eurasian lineages. A- Pre-Iron Age period; B- Iron Age period. Frequency values and
detailed information for populations 1–8 are shown in table 3. 1- Mongolia (Altai), 2- Gorny Altai, 3- West Kazakhstan, 4- Central Kazakhstan, 5- South
Kazakhstan, 6- East Kazakhstan, 7- SW Siberia, 8- Mongolia (Egyin Gol).
doi:10.1371/journal.pone.0048904.g002
Table 3. Frequency of West and East Eurasian haplogroups in ancient Eurasian populations prior to Iron Age and from the Iron
Age.
% Haplogroups
Period Geographic zone
Number of
samples West Eurasian East Eurasian References
Bronze Age Mongolia (Altai) 3 0 100 Present study
Neolithic and Bronze Age Gorny Altai 4 100 0 [3]
Bronze Age Kazakhstan 13 100 0 [7]
West 3 100 0
Central 1 100 0
South 2 100 0
East
#
7 100 0
Bronze Age SW Siberia 11 90.9 9.1 [4]
Iron Age, Pazyryk Altai Mongolia 19 57.9 42.1 Present study; [2]
Iron Age, Pazyryk Republic of Altai/Gorny Altai 10 40 60 [3,5,6]
Iron Age Kazakhstan 13 53.8 46.2 [7]
West 3 100 0
Central 8 37.5 62.5*
South 2 50 50*
Iron Age SW Siberia 15 66.7 33.3 [4]
Late Iron Age Mongolia (Egyin Gol) 46 10.9 89.1* [1]
#includes 5 samples Bronze/Iron Age (8th to 7th BC).
*Included one probable South Asia (Indian) lineage.
doi:10.1371/journal.pone.0048904.t003
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 5 November 2012 | Volume 7 | Issue 11 | e48904
Results
Authenticity of Results
Ancient DNA was retrieved and replicable unambiguous results
were obtained for the 19 individuals analysed. The genetic sex
determination was possible in fourteen of the nineteen individuals
(Table 1). With exception of one individual (BTG06.T10B),
morphological and genetic sex diagnoses were concordant. In
individual BTG06.T13 genetic sex based on Amelogenin and SRY
genes was contradictory, indicating a false negative amplification
of Y-Chromosome Amelogenin.
Table 2 shows the mtDNA results for the HVRI sequencing and
for the analysis of phylogenetically informative coding region
polymorphisms. In all the samples, there is a concordance between
the haplogroup inferred using SNPs typed along the coding region
and the one based on HVRI haplotype. No coincidences between
ancient and researchers’ sequences were found.
The cloning process was applied to the most informative HVRI
regions of all individuals. The results further verify that the data of
the sequences obtained represent the consensus in each individual
as shown in Table S3. Moreover, the samples replicated at the
Institut de Biologia Evolutiva yielded the same sequences found in
the Universitat Auto`noma de Barcelona, and proved the
independent reproducibility of the results generated.
Haplogroup Frequency and Sequence Diversity
The majority of the retrieved sequences (58%) fit into East
Eurasian lineages; namely to haplogroups A, C, D and G. On the
other hand, 42% of the individuals belong to West Eurasian
mtDNA haplogroups (J, K, HV, U, and T haplogroups) (Table 2).
Considering the chronology of burials, the three Bronze Age
samples represent three different haplotypes all of which can be
classified as haplogroup D. For Iron Age samples, the same
proportion (50%) of East and West Eurasian lineages were found
(Table 2).
Evidence of a perfect admixture between East Eurasian and
West Eurasian lineages is also observed in other Iron Age
populations from central Asia (Table 3 and Fig. 2B). On the other
hand, in Neolithic and Bronze Age populations around 100% of
the mtDNA lineages belong to East Eurasian or to Western
Eurasian haplogroups, depending on the geographic location
(Table 3 and Fig. 2A).
The number of mtDNA haplotypes, Nei gene diversity [59] and
nucleotide diversity [58,59] (based on HVRI sequences) for the
studied populations and for populations selected for comparison
are presented in table 4. Our Bronze Age samples of Mongolian
Altai (AMGBR) display the highest value of gene diversity.
However, this value must be interpreted with caution since only 3
individuals were analysed and the error associated to this
estimation is the highest reported. Concerning our Iron Age
population (PAZMG1), the value of diversity is in the range of
values observed in other ancient and present day populations from
the same geographical area. Regarding the nucleotidic diversity,
Bronze Age samples show the lowest values whereas Iron Age
samples show high values.
Phylogeographic Analysis
Network analysis using ancient Asia populations (Fig. 3 and 4)
displays the presence of both West Eurasian and East Eurasian
haplogroups. A good separation of haplotypes belonging to the
same haplogroup was achieved and the samples analysed in this
study are correctly positioned in the phylogeny.
Seven of the sixteen different haplotypes found in this study
(43.75%) are shared with other ancient populations used for
comparison. Concerning these haplotypes, it is evidenced that K
and T1 West Eurasian lineages detected in our Pazyryk sample
were also found in Bronze Age samples from Siberia and
Kazakhstan (Fig. 3).
Table 4. mtDNA HVRI diversity (from nucleotide positions
16051 to 16400) in Pazyryk population and populations used
for comparison.
POPULATION N
K (K%) S (S%) H
ˆ6sd p6sd
PAZMG2 3 2 (66.66) 8 (2.28) 0.66760.314 0.018960.015
BRNRA 20 8 (40.00) 14 (3.98) 0.73260.094 0.010860.006
LAJ 14 8 (57.15) 13 (3.70) 0.90160.058 0.011760.007
KZBR 13 10 (76.92) 18 (5.12) 0.92360.069 0.014460.008
TUB 11 9 (81.81) 23 (6.55) 0.94560.066 0.018060.010
TUV 63 36 (57.14) 52 (14.80) 0.95960.013 0.020860.011
GEOR 45 28 (62.22) 41 (11.70) 0.96460.016 0.015260.008
SIB 515 120 (23.30) 90 (25.65) 0.96660.003 0.022260.001
PAZMG1* 16 13 (81.25) 28 (7.99) 0.96760.036 0.02360.012
EGOL 46 26 (56.52) 38 (10.82) 0.96860.012 0.018360.010
KGEO 29 22 (75.86) 41 (11.68) 0.96860.028 0.014060.008
BUR 33 25 (75.75) 52 (14.81) 0.97460.012 0.019960.011
PAZRA 10 9 (90.00) 25 (7.12) 0.97860.054 0.007960.006
TURK 74 64 (86.50) 77 (21.93) 0.99460.004 0.01960.010
SBIR 15 13 (86.66) 30 (8.55) 0.98160.031 0.023260.013
KZIR 13 12 (92.30) 16 (4.55) 0.98260.035 0.011760.007
SBBR 11 10 (90.90) 25 (7.12) 0.98260.046 0.021360.012
CRT 20 17 (85.00) 37 (10.54) 0.98460.021 0.021160.012
KZAZ 27 23 (85.20) 35 (9.97) 0.98660.015 0.015760.009
KYR 52 38 (73.10) 61 (17.38) 0.98860.006 0.021060.011
KKUR 51 43 (84.30) 70 (19.95) 0.98860.008 0.021960.011
UZB 60 49 (81.67) 65 (18.51) 0.99160.005 0.021560.011
INMG 16 13 (81.25) 25 (7.12) 0.97560.029 0.021460.011
ALT 22 20 (90.90) 37 (10.54) 0.99160.017 0.020560.011
YUAN 15 14 (93.33) 20 (5.70) 0.99160.028 0.012860.007
TURKM 20 17 (85.00) 37 (10.54) 0.97960.025 0.02160.011
IRAN 233 176 (75.54) 120 (34.19) 0.99560.002 0.021560.011
MONG 138 100 (72.46) 96 (27.35) 0.99560.002 0.022360.012
KAL 99 85 (85.85) 79 (22.50) 0.99660.002 0.024560.013
KAZ 40 37 (92.50) 58 (16.52) 0.99660.007 0.020760.011
TAJ 20 20 (100) 43 (12.25) 1.00060.016 0.023460.013
AMGBR* 3 3 (100) 5 (1.42) 1.00060.272 0.010660.009
N- sample size, K- number of different haplotypes, S- number of polymorphic
sites, H
ˆ- gene diversity, p- nucleotide diversity.
*present study.
Ancient populations: AMGBR- Mongolia Altai Bronze Age, present study;
PAZMG1- Mongolia Altai, Pazyryk, present study; PAZMG2- Mongolia Altai,
Pazyryk; EGOL - Mongolia, Egyin Gol; PAZRA- Rep. Altai, Pazyryk; BRNRA- Rep.
Altai, Neolithic and Bronze Age; SBBR- Siberia, Bronze Age; SBIR- Siberia, Iron
Age; KZBR- Kazakhstan, Bronze Age; KZIR- Kazakhstan, Iron Age; LAJ- Lajia;
YUAN- Xinjiang; INMG- Inner Mongolia. Current populations: CRT- Crimean
Tartars; TURK- Turks; KZAZ- Kurds Zazaki; KKUR- Kurds Kurmanji; IRAN- Iraqis;
KGEO- Georgians Kurds; GEOR- Georgians; KYR- Kirgiz; UZB- Uzbeks; KAZ-
Kazaks; TURKM- Turkmens; TAJ- Tajiks; MONG- Mongols; TUV- Tuvans; TUB-
Tubalars; ALT- Altaians; BUR- Buriats; KAL- Kalmiks; SIB- Siberians.
Additional information concerning each population can be found in Table S2.
Ancient populations are displayed in italic.
doi:10.1371/journal.pone.0048904.t004
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 6 November 2012 | Volume 7 | Issue 11 | e48904
For non-shared haplotypes, additional haplotype comparisons
were performed including present-day data of Eurasian popula-
tions (data deposited in EMPOP and data from [64] and [65]); this
additional analysis allows verification that these haplotypes were
also present in at least one Eurasian population, with the exception
of two haplotypes from individuals AE05.T3 and TSK07.T1.
Thus, 87.5% of the haplotypes are shared with other ancient or
current Eurasian populations.
The mtDNA haplotypes of AE05.T3 and TSK07.T1, derived
respectively from other samples of the same haplogroup, by two
and three additional mutations (respectively, Figure 4 and 3). All
the additional mutations found in these samples are located in
positions considered mutational hotspots [66] and, some of them,
Figure 3. Median Joining Network of ancient N* haplogroup sequences. MtDNA sequences between positions 16051 and 16400, from
ancient populations from the Mongolia (present study and [1,2]), Russia [3,4,5,6], Kazakhstan [7] and China [8,9,10] were used. Additional information
concerning each population can be found in Table S2.
doi:10.1371/journal.pone.0048904.g003
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 7 November 2012 | Volume 7 | Issue 11 | e48904
have been associated to post-mortem DNA damage [67].
Notwithstanding, all the clones of both samples display the
mentioned mutations and sample TSK07.T1 was replicated in the
palaeogenetics laboratory of the Institut de Biologia Evolutiva.
Thus, although they have an unusual haplotype, the results
obtained for these two samples appear to be authentic.
A broad analysis of shared haplotypes in pre-Iron Age (present
study and [18,20,40]) and Iron Age populations (present study and
[10,11,18,19,20,36,40]) from Central Asia and South Siberia
demonstrate that only a small fraction 7 out of 72 (9.7%) of
lineages are shared among populations. Three haplotypes (all with
a West Eurasian origin) are shared between Iron Age and pre-Iron
Age populations, whereas four are shared between Iron Age
populations. Concerning non-shared haplotypes, 10 from 13
(77%) in pre-Iron Age populations, and 16 from 52 (31%) in Iron
Age populations, represent West Eurasian lineages. Thus, it seems
that the number of West Eurasian lineages does not increase in the
Iron Age.
The Multidimensional Scaling (MDS) representation of the
Slatkin genetic distance between pairs of ancient and modern
populations [61] shows a separation of populations, across
dimension 1, mainly based on the gradient of East and West
Eurasian lineages (Fig. 5). Iron Age populations are together in the
centre of coordinates showing an admixture of East Eurasian and
West Eurasian lineages. Present day populations from Central Asia
and Mongolia are grouped with ancient populations from the Iron
Age.
With exception of the Pazyryk samples from Mongolia
previously reported by [11], F
ST
values for pairs of populations
reveal that the Pazyryk populations seem to be genetically
homogeneous. Notwithstanding, according to [11], these three
samples belong to closely related individuals and cannot be
considered representative of the population. Moreover, the
Figure 4. Median Joining Network of ancient M* haplogroup sequences. MtDNA sequences between positions 16051 and 16400, from
ancient populations from the Mongolia (present study and [1,2]), Russia [3,4,5,6], Kazakhstan [7] and China [8,9,10] were used. Additional information
concerning each population can be found in Table S2.
doi:10.1371/journal.pone.0048904.g004
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 8 November 2012 | Volume 7 | Issue 11 | e48904
Pazyryk groups (excluding [11]) did not present significant genetic
differences with current Altaians. Although due to the small
sample size of the Pazyryk groups these results must be interpreted
with caution.
Discussion
Central Asians exhibit high frequencies of East Eurasian
mtDNA lineages, which are otherwise virtually absent in
populations from the Indo-Gangetic region and westwards, along
with a high prevalence of lineages of Western Eurasian origin
[3,33,68,69]. Also, high values of genetic diversity have been
reported using different genetic systems. Two hypotheses have
been put forward to explain this evidence: 1) Central Asians could
represent an early incubator of Eurasian variation, or 2) their
current genetic diversity could result from later admixture between
West and East Eurasian populations. In the light of current
knowledge, it seems that the second hypothesis is the most
probable [3,33] and although it is not possible to pinpoint all the
process that generated the central Asian diversity, it is clear that
the different gene pools that merged in their formation had already
diverged on the outskirts of the Eurasian continent [3].
It is widely accepted that animal domestication (starting ,5,000
YBP), particularly of the horse, gave the inhabitants of the Central
Asian steppes the opportunity to expand geographically in
different directions [12]. Historical records and archaeological
data indicate that the early populations’ movements across the
Eurasian steppe involved Indo-European-speaking people, being
most probably in the Altai Mountains the eastern boundary. By
the time of the 3rd century BC, Turkic-speaking peoples from the
Altai region began to migrate westwards, replacing Indo-European
languages in parts of Central Asia [12,13,14,70]. Today, the Altai
region is home to numerous Turkic-speaking ethnic groups, with a
mixed mtDNA gene pool between West and East Eurasia [71].
However, the origin of this genetic admixture was prior to
westward Turkic migrations and may be traced back to the Iron
Age in Central Asia, or even earlier in South Siberia [40,72]. With
the present study, we have aimed to unravel the early contacts
between European and Asian people in the Altai region by
analyzing ancient mtDNA in human remains from Bronze and
Iron Age burials of Mongolian Altai.
The high rate of success of the genetic analyses performed in the
present study, evidenced by the amplification of both nuclear and
mitochondrial DNA, suggests that the DNA of the samples is well
preserved. In accordance with other authors [18], this is the
expected result in samples that originated in cold and arid
environmental conditions such as those found at most of the Altai
sites. The agreement between morphological and genetic sex
diagnoses, the concordant results obtained using coding and non-
coding regions of mtDNA, the high haplotype diversity in
sequence motifs, the concordant results between different extracts
of the same sample, the clone results and the independent
replication of some samples in another ancient DNA laboratory,
all guarantee the authenticity of the obtained results [27,28,29].
Moreover, in terms of phylogenetic consistency, the observation of
16 different and phylogenetically plausible haplotypes among 19
ancient individuals and the coherence of the phylogenetic
networks build further points towards the authenticity of the
results [73].
Concerning Bronze Age samples from the Mongolian Altai
mountains analyzed in the present study, 100% of the mtDNA
lineages (3 different lineages from 2 archaeological sites) belong to
East Eurasian haplogroups, an opposite profile to that detected in
the West side of the Altai [18,20]. On the other hand, in the Iron
Age samples of Mongolian Altai, the same proportion (50%) of
East and Western Eurasian lineages were found, evidencing a
perfect admixture between East and Western Eurasian lineages as
in other Iron Age populations from central Asia and Siberia
[10,18,19,20,40]. Combined with the previous studies performed
so far in the Altai region, our results suggest that the Altai
represented a boundary to gene flow up to the beginning of the
Iron Age and that during the Scythian period of the Altai (5th to
Figure 5. Multidimensional scaling representation of the Slatkin’s linearized F
ST
pairwise genetic distance matrices between
populations. Genetic distance based on HVRI variation of ancient and current Eurasian populations. Ancient populations (in red): AMGBR- Mongolia
Altai Bronze Age, present study; PAZMG1- Mongolia Altai, Pazyryk, present study; PAZMG2- Mongolia Altai, Pazyryk; EGOL - Mongolia, Egyin Gol;
PAZRA- Rep. Altai, Pazyryk; BRNRA- Rep. Altai, Neolithic and Bronze Age; SBBR- Siberia, Bronze Age; SBIR- Siberia, Iron Age; KZBR- Kazakhstan, Bronze
Age; KZIR- Kazakhstan, Iron Age; LAJ- Lajia; YUAN- Xinjiang; INMG- Inner Mongolia. Current populations (in black): CRT- Crimean Tartars; TURK- Turks;
KZAZ- Kurds Zazaki; KKUR- Kurds Kurmanji; IRAN- Iraqis; KGEO- Georgians Kurds; GEOR- Georgians; KYR- Kirgiz; UZB- Uzbeks; KAZ- Kazaks; TURKM-
Turkmens; TAJ- Tajiks; MONG- Mongols; TUV- Tuvans; TUB- Tubalars; ALT- Altaians; BUR- Buriats; KAL- Kalmiks; SIB- Siberians. Additional information
concerning each population can be found in Table S2.
doi:10.1371/journal.pone.0048904.g005
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 9 November 2012 | Volume 7 | Issue 11 | e48904
3rd century BC) there were demographic events in the region that
led to a population admixture in both sides of the Altai.
Half of the shared haplotypes between ancient populations from
Central Asia and South Siberia represent lineages present in both
pre-Iron Age and Iron Age populations and all of these lineages
have a west Eurasian origin. Moreover, considering both shared
and non-shared haplotypes, it seems that the number of West
Eurasian lineages does not increase in the Iron Age. These results
allow us to hypothesise that the substrate of mtDNA lineages is
already present in pre-Iron Age populations of the central Asia
and that in the Iron Age (Scythian period) a population expansion
lead to the admixture of pre-existing lineages. Thus, the admixture
profile observed in the region during the Iron Age would not
derive from a migratory movement from west to east, as has been
hypothesised, but would represent a local population expansion in
different directions. This population expansion, however, would
be probably be a consequence of the introduction of new
technology by the adoption of a new culture, supporting the idea
of cultural transmission against the demic diffusion during
Scythian period.
The Pazyryk groups analysed so far appear to be genetically
homogeneous and they did not present significant genetic
differences to current Altaians. These results suggest that roots
of the current genetic diversity and admixture of the Altai region
in Central Asia could be traced back to the Iron Age.
Supporting Information
Table S1 Description of primers used and their references.
(DOCX)
Table S2 Ancient and current populations used in comparative
analysis. References corresponds to reference number in the
manuscript.
(DOC)
Table S3 Alignment of clone sequences.
(PDF)
Author Contributions
Conceived and designed the experiments: AM CS XJ. Performed the
experiments: MGR MS EG CLF. Analyzed the data: CS XJ MGR AM.
Contributed reagents/materials/analysis tools: AM MPA. Wrote the
paper: CS XJ AM MGR. Revised the paper: CS XJ AM MGR MS
CLF MPA.
References
1. Calafell F, Underhill P, Tolun A, Angelicheva D, Kalaydjieva L (1996) From
Asia to Europe: mitochondrial DNA sequence variability in Bulgarians and
Turks. Ann Hum Genet 60: 35–49.
2. Comas D, Calafell F, Mateu E, Perez-Lezaun A, Bosch E, et al. (1998) Trading
genes along the silk road: mtDNA sequences and the origin of central Asian
populations. Am J Hum Genet 63: 1824–1838.
3. Comas D, Plaza S, Wells RS, Yuldaseva N, Lao O, et al. (2004) Admixture,
migrations, and dispersals in Central Asia: evidence from maternal DNA
lineages. Eur J Hum Genet 12: 495–504.
4. Turbat T, Giscard PH, Batsukh D (2005) Pazyryk culture of Mongolia.
Mongolian Journal of Anthropology, Archaeology and Ethnology 2: 209–210.
5. Jordana X, Galtes I, Turbat T, Batsukh D, Garcia C, et al. (2009) The warriors
of the steppes: osteological evidence of warfare and violence from Pazyryk tumuli
in the Mongolian Altai. J Archaeol Sci 36: 1319–1327.
6. Van Noten F, Polosmak N (1995) The frozen tombs of the Scythians. Endeavour
19: 76–82.
7. Rudenko SI (1970) Frozen Tombs of Siberia: The Pazyryk Burials of Iron Age
Horsemen. First English Edition ed. London: J.M. Dent & Sons. 340 p.
8. Polosmak N, Van Noten F (1995) The Scythians from the Altai. Recherche 26:
524–530.
9. Clisson I, Keyser C, Francfort HP, Crubezy E, Samashev Z, et al. (2002) Genetic
analysis of human remains from a double inhumation in a frozen kurgan in
Kazakhstan (Berel site, Early 3rd Century BC). Int J Legal Med 116: 304–308.
10. Ricaut FX, Keyser-Tracqui C, Bourgeois J, Crubezy E, Ludes B (2004) Genetic
analysis of a Scytho-siberian skeleton and its implications for ancient Central
Asian migrations. Hum Biol 76: 109–125.
11. Pilipenko A, Romaschenko A, Molodin V, Parzinger H, Kobzev V (2010)
Mitochondrial DNA studies of the Pazyryk people (4th to 3rd centuries BC) from
northwestern Mongolia. Archaeol Anthropol Sci 2: 231–236.
12. Zvelebil M (1980) The rise of the nomads in central Asia. In: Sherratt A, ed. The
Cambridge Encyclopedia of Archaeology. New York: Cambridge University
Press. 252–256.
13. Mallory JP (1989) In search of the Indo-Europeans. London: Thames and
Hudson. 288 p.
14. Murphy E, Gokhman I, Chistov Y, Barkova L (2002) Prehistoric Old World
scalping: New cases from the cemetery of Aymyrlyg, South Siberia.
Am J Archaeol 106: 1–10.
15. Minajev V (1996) Les Xiongnu. Dossiers d’Arche´ologie 212: 74–83.
16. Voevoda MI, Sitnikova VV, Chikisheva TA, Romashchenko AG, Polos’mak
NV, et al. (1998) Molecular genetic analysis of mitochondrial DNA of
representatives of from the Pazyryk culture of Altai (IV-II centuries B.C.). Dokl
Akad Nauk 358: 564–566.
17. Voevoda ML, Romashchenko AG, Sitnikova VV, Shulgina EO, Kobsev VF
(2000) A comparison of mitochondrial DNA polymorphism in Pazyrik and
modern Eurasian populations. Archaeol Ethnol Anthropol Eurasia 4: 88–94.
18. Lalueza-Fox C, Sampietro ML, Gilbert MTP, Castri L, Facchini F, et al. (2004)
Unravelling migrations in the steppe: mitochondrial DNA sequences from
ancient Central Asians. Proc R Soc B-Biol Sci 271: 941–947.
19. Ricaut FX, Keyser-Tracqui C, Cammaert L, Crubezy E, Ludes B (2004)
Genetic analysis and ethnic affinities from two Scytho-Siberian skeletons.
Am J Phys Anthropol 123: 351–360.
20. Chikisheva TA, Gubina MA, Kulikov IV, Karafet TM, Voevoda MI, et al.
(2007) A paleogenetic study of the prehistoric populations of the Altai. Archaeol
Ethnol Anthropol Eurasia 4: 130–142.
21. Malgosa A, Montiel R, Dı
´az N, Solo´ rzano E, Smerling A, et al. (2005) Ancient
DNA: at modern look at the infections of the past. Recent Res Devel
Microbiology 9: 213–236.
22. Montiel R, Malgosa A, Subira` E (1997) Overcoming PCR inhibitors in ancient
DNA extracts from teeth. J Ancient Biomol 1: 221–225.
23. Simon M, Jordana X, Armentano N, Santos C, Diaz N, et al. (2011) The
presence of nuclear families in prehistoric collective burials revisited: the bronze
age burial of Montanissell Cave (Spain) in the light of aDNA. Am J Phys
Anthropol 146: 406–413.
24. Nakahori Y, Hamano K, Iwaya M, Nakagome Y (1991) Sex identification by
polymerase chain reaction using X-Y homologous primer. Am J Med Genet 39:
472–473.
25. Santos FR, Pandya A, Tyler-Smith C (1998) Reliability of DNA-based sex tests.
Nat Genet 18: 103.
26. Lalueza-Fox C, Rosas A, Estalrrich A, Gigli E, Campos PF, et al. (2011) Genetic
evidence for patrilocal mating behavior among Neandertal groups. Proc Natl
Acad Sci USA 108: 250–253.
27. Pa¨a¨ bo S, Poinar H, Serre D, Jaenicke-Despres V, Hebler J, et al. (2004) Genetic
analyses from ancient DNA. Annu Rev Genet 38: 645–679.
28. Gilbert MT, Bandelt HJ, Hofreiter M, Barnes I (2005) Assessing ancient DNA
studies. Trends Ecol Evol 20: 541–544.
29. Montiel R, Francalacci P, Malgosa A (2007) Ancient DNA and Biological
Anthropology: Believers vs Skeptics. In: Santos C, Lima M, eds. Recent
Advances in Molecular Biology and Evolution: Applications to Biological
Anthropology. Kerala: Research Signpost. 209–249.
30. Hall TA (1999) BioEdit: a user-friendly biological sequence alignment editor and
analysis program for Windows 95/98/NT. Nucl Acids Symp Ser 41: 95–98.
31. Andrews RM, Kubacka I, Chinnery PF, Lightowlers RN, Turnbull DM, et al.
(1999) Reanalysis and revision of the Cambridge reference sequence for human
mitochondrial DNA. Nat Genet 23: 147.
32. van Oven M, Kayser M (2009) Updated comprehensive phylogenetic tree of
global human mitochondrial DNA variation. Hum Mutat 30: E386–394.
33. Quintana-Murci L, Chaix R, Wells RS, Behar DM, Sayar H, et al. (2004)
Where west meets east: the complex mtDNA landscape of the southwest and
Central Asian corridor. Am J Hum Genet 74: 827–845.
34. Chandrasekar A, Kumar S, Sreenath J, Sarkar BN, Urade BP, et al. (2009)
Updating phylogeny of mitochondrial DNA macrohaplogroup m in India:
dispersal of modern human in South Asian corridor. PLoS One 4: e7447.
35. Derenko M, Malyarchuk B, Denisova G, Perkova M, Rogalla U, et al. (2012)
Complete mitochondrial DNA analysis of eastern Eurasian haplogroups rarely
found in populations of northern Asia and eastern Europe. PLoS One 7: e32179.
36. Keyser-Tracqui C, Crubezy E, Ludes B (2003) Nuclear and mitochondrial DNA
analysis of a 2,000-year-old necropolis in the Egyin Gol Valley of Mongolia.
Am J Hum Genet 73: 247–260.
37. Changchun Y, Li X, Xiaolei Z, Hui Z, Hong Z (2006) Genetic analysis on
Tuoba Xianbei remains excavated from Qilang Mountain Cemetery in Qahar
Right Wing Middle Banner of Inner Mongolia. FEBS Lett 580: 6242–6246.
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 10 November 2012 | Volume 7 | Issue 11 | e48904
38. Gao SZ, Yang YD, Xu Y, Zhang QC, Zhu H, et al. (2007) Tracing the genetic
history of the Chinese people: mitochondrial DNA analysis of aneolithic
population from the Lajia site. Am J Phys Anthropol 133: 1128–1136.
39. Gao S, Cui Y, Yang Y, Duan R, Abuduresule I, et al. (2008) Mitochondrial
DNA analysis of human remains from the Yuansha site in Xinjiang, China. Sci
China C Life Sci 51: 205–213.
40. Keyser C, Bouakaze C, Crubezy E, Nikolaev VG, Montagnon D, et al. (2009)
Ancient DNA provides new insights into the history of south Siberian Kurgan
people. Hum Genet 126: 395–410.
41. Shields GF, Schmiechen AM, Frazier BL, Redd A, Voevoda MI, et al. (1993)
mtDNA sequences suggest a recent evolutionary divergence for Beringian and
northern North American populations. Am J Hum Genet 53: 549–562.
42. Starikovskaya YB, Sukernik RI, Schurr TG, Kogelnik AM, Wallace DC (1998)
mtDNA diversity in Chukchi and Siberian Eskimos: implications for the genetic
history of Ancient Beringia and the peopling of the New World. Am J Hum
Genet 63: 1473–1491.
43. Schurr TG, Sukernik RI, Starikovskaya YB, Wallace DC (1999) Mitochondrial
DNA variation in Koryaks and Itel’men: population replacement in the Okhotsk
Sea-Bering Sea region during the Neolithic. Am J Phys Anthropol 108: 1–39.
44. Comas D, Calafell F, Bendukidze N, Fananas L, Bertranpetit J (2000) Georgian
and kurd mtDNA sequence analysis shows a lack of correlation between
languages and female genetic lineages. Am J Phys Anthropol 112: 5–16.
45. Kong QP, Yao YG, Liu M, Shen SP, Chen C, et al. (2003) Mitochondrial DNA
sequence polymorphisms of five ethnic populations from northern China. Hum
Genet 113: 391–405.
46. Mishmar D, Ruiz-Pesini E, Golik P, Macaulay V, Clark AG, et al. (2003)
Natural selection shaped regional mtDNA variation in humans. Proc Natl Acad
Sci USA 100: 171–176.
47. Mergen H, O
¨ner R, O
¨ner C (2004 ) Mitochondrial DNA sequence variation in
the Anatolian Peninsula (Turkey). J Genet 83: 39–47.
48. Nasidze I, Quinque D, Dupanloup I, Cordaux R, Kokshunova L, et al. (2005)
Genetic evidence for the Mongolian ancestry of Kalmyks. Am J Phys Anthropol
128: 846–854.
49. Nasidze I, Quinque D, Ozturk M, Bendukidze N, Stoneking M (2005) MtDNA
and Y-chromosome variation in Kurdish groups. Ann Hum Genet 69: 401–412.
50. Starikovskaya EB, Sukernik RI, Derbeneva OA, Volodko NV, Ruiz-Pesini E, et
al. (2005) Mitochondrial DNA diversity in indigenous populations of the
southern extent of Siberia, and the origins of Native American haplogroups. Ann
Hum Genet 69: 67–89.
51. Nasidze I, Quinque D, Rahmani M, Alemohamad SA, Stoneking M (2006)
Concomitant replacement of language and mtDNA in South Caspian
populations of Iran. Curr Biol 16: 668–673.
52. Pakendorf B, Novgorodov IN, Osakovskij VL, Danilova AP, Protod’jakonov AP,
et al. (2006) Investigating the effects of prehistoric migrations in Siberia: genetic
variation and the origins of Yakuts. Hum Genet 120: 334–353.
53. Derenko M, Malyarchuk B, Grzybowski T, Denisova G, Dambueva I, et al.
(2007) Phylogeographic analysis of mitochondrial DNA in northern Asian
populations. Am J Hum Genet 81: 1025–1041.
54. Pakendorf B, Novgorodov IN, Osakovskij VL, Stoneking M (2007) Mating
patterns amongst Siberian reindeer herders: inferences from mtDNA and Y-
chromosomal analyses. Am J Phys Anthropol 133: 1013–1027.
55. Gokcumen O, Dulik MC, Pai AA, Zhadanov SI, Rubinstein S, et al. (2008)
Genetic variation in the enigmatic Altaian Kazakhs of South-Central Russia:
Insights into Turkic population history. Am J Phys Anthropol 136: 278–293.
56. Nasidze I, Quinque D, Rahmani M, Alemohamad SA, Stoneking M (2008)
Close genetic relationship between Semitic-speaking and Indo-European-
speaking groups in Iran. Ann Hum Genet 72: 241–252.
57. Volodko NV, Starikovskaya EB, Mazunin IO, Eltsov NP, Naidenko PV, et al.
(2008) Mitochondrial genome diversity in arctic Siberians, with particular
reference to the evolutionary history of Beringia and Pleistocenic peopling of the
Americas. Am J Hum Genet 82: 1084–1100.
58. Tajima F (1983) Evolut ionary relationship of DNA se quences in fin ite
populations. Genetics 105: 437–460.
59. Nei M (1987) Molecular evolutionary genetics. Columbia University Press,New
York. 512 p.
60. Excoffier L, Laval G, Schneider S (2005) Arlequin (version 3.0): an integrated
software package for population genetics data analysis. Evol Bioinform Online 1:
47–50.
61. Slatkin M (1995) A measure of population subdivision based on microsatellite
allele frequencies. Genetics 139: 457–462.
62. Bandelt HJ, Forster P, Rohl A (1999) Median-joining networks for inferring
intraspecific phylogenies. Mol Biol Evol 16: 37–48.
63. Santos C, Fregel R, Cabrera VM, Gonzalez AM, Larruga JM, et al. (2010)
Mitochondrial DNA patterns in the Macaronesia islands: Variation within and
among archipelagos. Am J Phys Anthropol 141: 610–619.
64. Cordaux R, Saha N, Bentley GR, Aunger R, Sirajuddin SM, et al. (2003)
Mitochondrial DNA analysis reveals diverse histories of tribal populations from
India. Eur J Hum Genet 11: 253–264.
65. Kivisild T, Rootsi S, Metspalu M, Mastana S, Kaldma K, et al. (2003) The
genetic heritage of the earliest settlers persists both in Indian tribal and caste
populations. Am J Hum Genet 72: 313–332.
66. Soares P, Ermini L, Thomson N, Mormina M, Rito T, et al. (2009) Correcting
for purifying selection: an improved human mitochondrial molecular clock.
Am J Hum Genet 84: 740–759.
67. Gilbert MT, Willerslev E, Hansen AJ, Barnes I, Rudbeck L, et al. (2003)
Distribution patterns of postmortem damage in human mitochondrial DNA.
Am J Hum Genet 72: 32–47.
68. Derenko MV, Grzybowski T, Malyarchuk BA, Dambueva IK, Denisova GA, et
al. (2003) Diversity of mitochondrial DNA lineages in South Siberia. Ann Hum
Genet 67: 391–411.
69. Metspalu M, Kivisild T, Bandelt HJ, Richards M, Villems R (2006) The Pioneer
Settlement of Modern Humans in Asia. In: Bandelt HJ, Macaulay V, Richards
R, eds. Human Mitochondrial DNA and the Evolution of Homo sapiens. Berlin:
Springer. 181–199.
70. Cavalli-Sforza L, Piazza A, Menozzi P (1994) The history and geography of
human genes. Princeton, NJ: Princeton University Press. 1032 p.
71. Dulik MC, Zhadanov SI, Osipova LP, Askapuli A, Gau L, et al. (2012)
Mitochondrial DNA and Y chromosome variation provides evidence for a
recent common ancestry between Native Americans and Indigenous Altaians.
Am J Hum Genet 90: 229–246.
72. Li C, Li H, Cui Y, Xie C, Cai D, et al. (2010) Evidence that a West-East
admixed population lived in the Tarim Basin as early as the early Bronze Age.
BMC Biol 8: 1–12.
73. Bandelt HJ (2005) Mosaics of ancient mitochondrial DNA: positive indicators of
nonauthenticity. Eur J Hum Genet 13: 1106–1112.
Origin of Population Admixture at Central Asia
PLOS ONE | www.plosone.org 11 November 2012 | Volume 7 | Issue 11 | e48904