On Thu, 05 Oct 2006 20:47:31 +0530, sastry wrote:
> On Thu October 5 2006 8:09 pm, Udhay Shankar N wrote:
> > IIRC, another DNA tied a demolition crew supervisor to Genghis Khan
> > in the first chapter of HHGTTG [1].
>
> IIRC Gengis Khan genes have been found in 25% (or some such
> ridiculously high proportion) of all humans.
I looked for evidence of this assertion, and I didn't find any;
apparently Genghis's corpse has been lost for some time, so nobody
knows what his genes were. At least, that's what most of the
references I found said. Do you have an update?
Perhaps you were thinking of the article that found 25% of the
Y-chromosomes among men of the Hazara tribe in Pakistan belonged to
the "star cluster", which the researchers believe came from Genghis
Khan?
The same article also found that 8% of men in the former Mongol empire
have the cluster in their Y-chromosomes. Presumably, then, nearly
100% of the people in that area are descended from the Khan by some
path or other.
Related refs:
> "Descent from Genghis Khan", from Wikipedia
http://en.wikipedia.org/wiki/Descent_from_Genghis_Khan
> "Genghis Khan: most prolific man in history?", by Thorgeir Blund, on
Kuro5hin, 2003-02-04
http://www.kuro5hin.org/story/2003/2/8/214236/6651
> "Genghis Khan: Liberal Philosopher King?", by Stephen Healey, no date
given, in "SOMA Review"
http://www.somareview.com/genghis_khan.cfm
> "The Genetic Legacy of the Mongols", by Tatiana Zerjal, et al.,
Am. J. Hum. Genet., 72:717-721, 2003, text included below
http://www.journals.uchicago.edu/AJHG/journal/issues/v72n3/024530/024530.text.html?erFrom=-4292852394516950414Guest
The Genetic Legacy of the Mongols
Tatiana Zerjal,[1] Yali Xue,[1,2] Giorgio Bertorelle,[3] R. Spencer
Wells,[4] Weidong Bao,[1,5] Suling Zhu,[1,5] Raheel Qamar,[1,6] Qasim
Ayub,[1,6] Aisha Mohyuddin,[1,6] Songbin Fu,[2] Pu Li,[2] Nadira
Yuldasheva,[4,7] Ruslan Ruzibakiev,[7] Jiujin Xu,[5] Qunfang Shu,[5]
Ruofu Du,[5] Huanming Yang,[5] Matthew E. Hurles,[8] Elizabeth
Robinson,[1],* Tudevdagva Gerelsaikhan,[1], ** Bumbein Dashnyam,[9]
S. Qasim Mehdi,[5] and Chris Tyler-Smith[1]
[1] Department of Biochemistry, University of Oxford, Oxford;
[2] Department of Medical Biology, Harbin Medical University, Harbin, China;
[3] Dipartimento di Biologia, Universitá di Ferrara, Ferrara, Italy;
[4] Wellcome Trust Centre for Human Genetics, University of Oxford,
Headington, United Kingdom;
[5] Institute of Genetics, Chinese Academy of Sciences, Beijing;
[6] Biomedical and Genetic Engineering Labs, Islamabad;
[7] Institute of Immunology, Academy of Sciences, Tashkent, Uzbekistan;
[8] McDonald Institute, University of Cambridge, Cambridge, United Kingdom; and
[9] Institute of Biotechnology, Mongolian Academy of Sciences,
Ulaanbaatar, Mongolia
* Present affiliation: Combinatorx, Boston
** Present affiliation: National Institute of Dental and Craniofacial
Research, National Institutes of Health, Bethesda.
Received September 27, 2002; accepted for publication November 25, 2002;
electronically published January 17, 2003.
We have identified a Y-chromosomal lineage with several unusual
features. It was found in 16 populations throughout a large region
of Asia, stretching from the Pacific to the Caspian Sea, and was
present at high frequency: ~8% of the men in this region carry it,
and it thus makes up ~0.5% of the world total. The pattern of
variation within the lineage suggested that it originated in
Mongolia ~1,000 years ago. Such a rapid spread cannot have occurred
by chance; it must have been a result of selection. The lineage is
carried by likely male-line descendants of Genghis Khan, and we
therefore propose that it has spread by a novel form of social
selection resulting from their behavior.
Address for correspondence and reprints: Dr. Chris Tyler-Smith,
Department of Biochemistry, University of Oxford, South Parks Road,
Oxford OX1 3QU, UK. E-mail: [EMAIL PROTECTED]
The patterns of variation found in human DNA are usually considered to
result from a balance between neutral processes and natural
selection. Among the former, mutation, recombination, and migration
increase variation, whereas genetic drift decreases it. Natural
selection can act to remove deleterious variants (purifying selection),
maintain polymorphism (balancing selection), or produce a trend
(directional selection). Clear examples of the latter are rare in
humans, but probable cases, such as those associated with resistance to
malaria (Hamblin and Di Rienzo 2000) or unidentified pathogens (Stephens
et al. 1998), can be recognized by the "signature" they leave in the
genome. The rapid increase in frequency of the selected allele and its
linked sequences results in a haplotype that is found at higher
frequency than would be expected from its degree of variation. We have
now identified such a haplotype on the Y chromosome, but we suggest that
its spread results not from a biological advantage, but from human
activities recorded in history.
In surveys of DNA variation in Asia, we typed 2,123 men with >=32
markers to produce a Y haplotype for each man; these included 1,126
individuals described elsewhere (Qamar et al. 2002; Zerjal et
al. 2002). Over 90% of the haplotypes showed the usual pattern
(Mohyuddin et al. 2001): most males had a unique code; and the few
haplotypes present in more than one individual were generally found
within the same population. However, we also saw one pattern that was
novel in two respects. First, there was a high frequency of a cluster of
closely related lineages, collectively called the "star cluster"
(fig. 1, shaded area). Second, star-cluster chromosomes were found in 16
populations throughout a large geographical area extending from Central
Asia to the Pacific (fig. 2); thus, they do not result from an event
specific to any single population. We can deduce the most likely time to
the most recent common ancestor (TMRCA) and place of origin of this
unusual lineage from the observed genetic variation. To do this, it is
first necessary to distinguish star-cluster chromosomes from the
remainder. For this, we used the criterion that haplotypes linked to the
central one in the shaded area of the network without gaps would be
included (fig. 1). We then used two approaches to calculate a TMRCA for
the star-cluster chromosomes. The program BATWING (Wilson and Balding
1998) uses models of both mutation and population processes, which were
specified as described elsewhere (Qamar et al. 2002). With this program,
we estimated ~1,000 years for the TMRCA (95% confidence interval limits
~700--1,300 years). The use of alternative demographic models with
constant or exponentially increasing population size changed the
estimate by <10%. A method that does not consider population structure
(Morral et al. 1994), rho, suggested ~860 (~590--1,300) years. In both
calculations, we assumed a generation time of 30 years. The origin was
most likely in Mongolia, where the largest number of different
star-cluster haplotypes is found (fig. 1). Thus, a single male line,
probably originating in Mongolia, has spread in the last ~1,000 years
to represent ~8% of the males in a region stretching from northeast
China to Uzbekistan. If this spread were due to a general population
expansion, we would expect to find multiple lineages with the same
characteristics of high frequency and presence in multiple populations,
but we do not (Zerjal et al. 2002). The star-cluster pattern is unique.
Figure 1 (omitted from plain text version) Median-joining network
(Bandelt et al. 1999) representing Y-chromosomal variation within
haplogroup C*(xC3c). Chromosomes were typed with a minimum of 16
binary markers (Qamar et al. 2002; Zerjal et al. 2002; our
unpublished observations), including RPS4Y and M48, to define the
lineage C*(xC3c) (Y-Chromosome-Consortium 2002), also known as
haplogroup 10, derived for RPS4Y and ancestral for M48. Sixteen Y
microsatellites were also typed, but DYS19 was excluded from the
network analysis because it is duplicated in haplogroup C. The
central star-cluster profile is 10-16-25-10-11-13-14-12-11-11-11-
12-8-10-10, for the loci DYS389I-DYS389b-DYS390-DYS391-DYS392-
DYS393-DYS388-DYS425-DYS426-DYS434-DYS435-DYS436-DYS437-DYS438-
DYS439. Circles represent lineages, area is proportional to
frequency, and color indicates population of origin. Lines represent
microsatellite mutational differences.
Figure 2 (omitted from plain-text version) Geographical distribution
of star-cluster chromosomes. Populations are shown as circles with
an area proportional to sample size; star-cluster chromosomes are
indicated by green sectors. The shaded area represents the extent of
Genghis Khan's empire at the time of his death (Morgan 1986).
This rise in frequency, if spread evenly over ~34 generations, would
require an average increase by a factor of ~1.36 per generation and is
thus comparable to the most extreme selective events observed in natural
populations, such as the spread of melanic moths in 19th-century England
in response to industrial pollution (Edleston 1865). We evaluated
whether it could have occurred by chance. If the population growth rate
is known, it is possible to test whether the observed frequency of a
lineage is consistent with its level of variation, assuming neutrality
(Slatkin and Bertorelle 2001). Using this method, we estimated the
chance of finding the low degree of variation observed in the star
cluster, with a current frequency of ~8%, under neutral
conditions. Even with the demographic model most likely to lead to rapid
increase of the lineage, double exponential growth, the probability was
<10^-237; if the mutation rate were 10 times lower, the probability
would still be <10^-10. Thus, chance can be excluded: selection must
have acted on this haplotype.
Could biological selection be responsible? Although this possibility
cannot be entirely ruled out, the small number of genes on the Y
chromosome and their specialized functions provide few opportunities for
selection (Jobling and Tyler-Smith 2000). It is therefore necessary to
look for alternative explanations. Increased reproductive fitness,
transmitted socially from generation to generation, of males carrying
the same Y chromosome would lead to the increase in frequency of their Y
lineage, and this effect would be enhanced by the elimination of
unrelated males. Within the last 1,000 years in this part of the world,
these conditions are met by Genghis (Chingis) Khan (c. 1162--1227) and
his male relatives. He established the largest land empire in history
and often slaughtered the conquered populations, and he and his close
male relatives had many children. Although the Mongol empire soon
disintegrated as a political unit, his male-line descendants ruled large
areas of Asia for many generations. These included China, where the Yüan
Dynasty emperors remained in power until 1368, after which the Mongols
continued to dominate the country north of the Great Wall for several
more centuries, and the region west to the Aral Sea, where the Chaghatai
Khans ruled. Although their power diminished over time, they remained at
Kashghar near the Kyrgyzstan/China border until the middle of the 17th
century (Morgan 1986).
It is striking that the boundary of the Mongol empire when Genghis Khan
died (fig. 2), which also corresponds to the boundaries of the regions
controlled by later Khans, matches the distribution of star-cluster
chromosomes closely, with one exception: the Hazaras. We, therefore,
wished to compare Genghis Khan's Y profile with the star cluster. It is
not possible to examine his remains directly, but history provides an
alternative. The Hazaras of Pakistan have a Mongol origin (Qamar et
al. 2002), and many consider themselves to be direct male-line
descendants of Genghis Khan. A genealogy documenting these links has
been constructed from their oral history (Mousavi 1998). A large
proportion of the Hazara profiles do indeed lie in the star cluster,
which is not otherwise seen in Pakistan (fig. 2), thus supporting their
oral tradition and suggesting that Genghis Khan carried the star-cluster
haplotype.
The Y chromosome of a single individual has spread rapidly and is now
found in ~8% of the males throughout a large part of Asia. Indeed, if
our sample is representative, this chromosome will be present in about
16 million men, ~0.5% of the world's total. The available evidence
suggests that it was carried by Genghis Khan. His Y chromosome would
obviously have had ancestors, and our best estimate of the TMRCA of
star-cluster chromosomes lies several generations before his
birth. Several scenarios, which are not mutually exclusive, could
explain its rapid spread: (1) all populations carrying star-cluster
chromosomes could have descended from a common ancestral population in
which it was present at high frequency; (2) many or most Mongols at the
time of the Mongol empire could have carried these chromosomes; (3) it
could have been restricted to Genghis Khan and his close male-line
relatives, and this specific lineage could have spread as a result of
their activities. Explanation 1 is unlikely because these populations do
not share other Y haplotypes, and explanation 2 is difficult to
reconcile with the high Y-haplotype diversity of modern Mongolians
(Zerjal et al. 2002). The historically documented events accompanying
the establishment of the Mongol empire would have contributed directly
to the spread of this lineage by Genghis Khan and his relatives, but
perhaps as important was the establishment of a long-lasting male
dynasty. This scenario shows selection acting on a group of related men;
group selection has been much discussed (Wilson and Sober 1994) and is
distinguished by the property that the increased fitness of the group is
not reducible to the increased fitness of the individuals. It is unclear
whether this is the case here. Our findings nevertheless demonstrate a
novel form of selection in human populations on the basis of social
prestige. A founder effect of this magnitude will have influenced allele
frequencies elsewhere in the genome: mitochondrial DNA lineages will not
be affected, since males do not transmit their mitochondrial DNA, but,
in the simplest models, the founder male will have been the ancestor of
each autosomal sequence in ~4% of the population and X-chromosomal
sequence in ~2.7%, with implications for the medical genetics of the
region. Large-scale changes to patterns of human genetic variation can
occur very quickly. Although local influences of this kind may have been
common in human populations, it is, perhaps, fortunate that events of
this magnitude have been rare.
Acknowledgments
---------------
We thank all DNA donors, for making this work possible; Ed Southern, for
encouragement and comments on the manuscript; Jaume Bertranpetit, for
helpful discussions; Ian Wilson, for modifying BATWING to allow 16
different mutation rates to be used; Askar Mousavi, for information on
the Hazaras; Christine Keyser, for information about the genetics of
ancient Mongolian populations; and Felipe Fernámdez-Armesto, for
historical discussions. This work was supported by a Joint Project from
the Royal Society and the National Natural Science Foundation of China
and a Collaborative Research Initiative Grant from the Wellcome Trust;
T. Z. was supported by the Wellcome Trust.
References
----------
* Bandelt HJ, Forster P, Rohl A (1999) Median-joining networks for
inferring intraspecific phylogenies. Mol Biol Evol 16:37--48
* Edleston RS (1865) Amphydasis betularia. Entomologist 2:150
* Hamblin MT, Di Rienzo A (2000) Detection of the signature of
natural selection in humans: evidence from the Duffy blood group
locus. Am J Hum Genet 66:1669--1679
* Jobling MA, Tyler-Smith C (2000) New uses for new haplotypes: the
human Y chromosome, disease and selection. Trends Genet
16:356--362
* Mohyuddin A, Ayub Q, Qamar R, Zerjal T, Helgason A, Mehdi SQ,
Tyler-Smith C (2001) Y-chromosomal STR haplotypes in Pakistani
populations. Forensic Sci Int 118:141--146
* Morgan D (1986) The Mongols. Blackwell Publishers, Oxford
* Morral N, Bertranpetit J, Estivill X, Nunes V, Casals T, Gimenez
J, Reis A, et al (1994) The origin of the major cystic fibrosis
mutation (delta-F508) in European populations. Nat Genet
7:169--175
* Mousavi SA (1998) The Hazaras of Afghanistan. Curzon Press,
Richmond
* Qamar R, Ayub Q, Mohyuddin A, Helgason A, Mazhar K, Mansoor A,
Zerjal T, Tyler-Smith C, Mehdi SQ (2002) Y-chromosomal DNA
variation in Pakistan. Am J Hum Genet 70:1107--1124
* Slatkin M, Bertorelle G (2001) The use of intraallelic variability
for testing neutrality and estimating population growth
rate. Genetics 158:865--874
* Stephens JC, Reich DE, Goldstein DB, Shin HD, Smith MW, Carrington
M, Winkler C, et al (1998) Dating the origin of the CCR5-delta-32
AIDS-resistance allele by the coalescence of haplotypes. Am J Hum
Genet 62:1507--1515
* Wilson DS, Sober S (1994) Re-introducing group selection to the
human behavioral sciences. Behavioral Brain Sci 17:585--654
* Wilson IJ, Balding DJ (1998) Genealogical inference from
microsatellite data. Genetics 150:499--510
* Y-Chromosome-Consortium (2002) A nomenclature system for the tree
of human Y-chromosomal binary haplogroups. Genome Res 12:339--348
* Zerjal T, Wells RS, Yuldasheva N, Ruzibakiev R, Tyler-Smith C
(2002) A genetic landscape reshaped by recent events:
Y-chromosomal insights into Central Asia. Am J Hum Genet
71:466-482
