Ancient steppe populations: hints of things to come

A reader alerts me to this research summary from a German government site (pdf). The research covered seems to be that of Joachim Burger's group.

The relevant chapter is:

Schritte im weiten Raum: Neue Blicke auf Zivilisationen der Eurasischen Steppe
[steps in the vast space: New Views on civilizations of the Eurasian steppe]

I invite my German readers to translate the most interesting parts of the chapter in the comments (or at least to summarize them). A few observations on what I've been able to make sense of:

• Heterogeneity of North Pontic steppe groups with differences between Catacomb culture and earlier Yamnaya individuals
• "European" light pigmentation but with darker eyes 
• Iron Age nomadic horsemen of Central Asia/South Siberia were mixed West/East Eurasian

Here are some (little) processed Google Translate portions to whet your appetite:

[The first part of the project looked for copper and Bronze Age cultures of the steppe west and north of the Black Sea (Fig. 1). In the Late Bronze Age (around 3000 BC) came here the very mobile Yamnaya culture in appearance, their population and influence radius - as the investigations showed - apparently at the same time expanding consolidated. With the Yamnaya culture is a single burial rites used in so-called pit graves under kurgans (grave mound). Also this wont Halbno addition maggots strong trading relationships across the steppe. Around 2500 BC, they were replaced by the less mobile Katakombengrab-culture whose dissemination conduction region was significantly smaller. Population genetic analyzes of DNA occupied by the late copper to the Middle Bronze Age, a steadily increasing genetic distance between those cul tures. Between copper and time Katakombengrab culture is the genetic distance is greatest. Here the differences are much more pronounced than between early Chalcolithic cultures and Yamnaya population. This population genetic change could be an indication of discontinuity and population changes due to migration. An archaeological site of suspected immigration from eastern steppe areas but at least on the female side hardly taken place: For Central Asia typical DNA lines do not occur in the studied populations. Despite the genetic differences within the un the investigated groups are with them to popu lations, which are without doubt be described as European.Here the differences are much more pronounced than between early Chalcolithic cultures and Yamnaya population. This population genetic change could be an indication of discontinuity and population changes due to migration. An archaeological site of suspected immigration from eastern steppe areas but at least on the female side hardly taken place: For Central Asia typical DNA lines do not occur in the studied populations. Despite the genetic differences within the un the investigated groups are with them to popu lations, which are without doubt be described as European. DNA markers with known phenotype suggest a continuity between the North Pontic area of ​​4 / 3 Millennium BC and today's Europeans out. For instance, have all examined individuals tierungstyp on a bright pigments, as is prevalent in Europe today. Only the eye color has been dark in comparison to today.]

[The second part of the project was devoted to the population dynamics of early Iron Age peoples of nomadic horsemen in the Eurasian steppe belt. Here were 900-300 BC disseminated numerous highly mobile populations that are associated with the so-called Scythian or Sakian culture (Fig. 2). The groups studied are from the areas of eastern Kazakhstan, Altai mountains, Minusinsk Basin and Tuva. They all consist of a mixture of DNALinien, which today is a part of Central and East Asia and the other in Europe. Ity of the ground because this way the populations have a remarkably high level of genetic diversity that characterizes the Altai population today.

...

The Tagar Culture (Minusinsk Basin) this shows the greatest genetic - but also cultural - distance to all other groups. Although it chronologically corresponds to the Pazyryk culture of the Altai (5th-3rd century BC) seems to be present here genetic isolation. Between the Pazyryk culture and the significantly older findings from Tuva (7 / 6th century BC), however, the genetic distance in spite of the time interval is very small. Amazingly, has the Pazyryk culture also within its range a geographic substructure: Divided into Kazakh Altai, and Cuja Ukok plateau region, show the nomadic horsemen of Cuja region in relation to the other two groups increased genetic distance.]

“Mismodelling Indo-European Origins” Talk

Martin Lewis and Asya Pereltsvaig have been critical of the recent paper on Indo-European origins on the GeoCurrents blog, and they recently gave a talk at Stanford on the topic.



Some relevant past posts:

• U7 in Rostov Scythians
• The Indo-European invasion of the Baltic
• IE-speaking West Europeans are West Asian-admixed relative to Non-IE speaking Basques
• Indo-European genetic signatures in an Orcadian and a Lithuanian
• The Bronze Age Indo-European invasion of Europe
• Assessment of ancient European DNA with 'globe13'

I think that the Indo-European question has been debated for more than two centuries without any clear resolution. Over the next few years, I think that either of two things will occur:

• A clear unambiguous pattern of expansion mimicking the IE dispersal will appear in ancient DNA, providing the "smoking gun" for one of the different hypotheses.
• No such Eurasian-wide pattern will emerge, and it will turn out that Indo-Europeanization was effected with minimum dispersal of populations.

I suspect the former will be the case, but it will nonetheless be interesting to see how the different parties coming from archaeology and linguistics will react to the (archaeo)genetic avalanche that will doubtlessly provide us with new information about the prehistoric past.

U7 in Rostov Scythians

I found it quite interesting that in terms of mtDNA, the Rostov Scythians studied by der Sarkissian resembled closely the Shugnans of Tajikistan, who speak an eastern Iranian language. The author finds links between the Scythians and the "Central Asian Corridor", in particular with respect to mtDNA haplogroup U7.

This "Central Asian Corridor" sensu der Sarkissian (Iraq, Iran, Pakistan, India) seems to touch Frachetti's Inner Asian Mountain Corridor (shown below) in the region of the Pamirs.

Interestingly, the Sughnans belong, anthropologically to the Pamir-Ferghana type, which was also called Central Asian interfluvial type, the rivers in question being the Oxus and Jaxartes (Amu Darya and Syr Darya). And, of course, between these two rivers was the heartland of the Bactria Margiana Archaeological Complex, which I have previously linked with the Indo-Iranians.

Wells et al. studied Y-chromosomes of Sughnans, Yagnobis and other Iranic survivals of Tajikistan more than 10 years ago, and it will be very well worth revisiting them with newer methods. The area east of the Caspian and west of the IAMC intersects so much history, that any data from from it (new or ancient) would be extremely useful.

In my own experiments there has been an unambiguous "South Asian" genetic component in almost all Iranic peoples, even the westernmost Kurds. While the interpretation of this component is not easy, it does point to a genetic relationship between its possessors and Central/South Asia, with notable contrasts between Kurds/Iranians and their non-Iranic Armenian/Anatolian/Caucasian neighbors.

The occurrence of mtDNA haplogroup U7 in the Rostov Scythians is also consistent with a link between the Iranian nomads who penetrated into Europe with the area east of the Caspian, and it is also, of course, consistent with the narrative of Herodotus who recorded the migration of the Scythians into Europe.

There is a widely held theory that the origin of the Indo-Iranians are to be sought in eastern Europe. That theory appears inconsistent both with the "South Asian" autosomal signal in Iranic groups, and with the mtDNA evidence. Consider, again, the evidence of der Sarkissian:

Now, if Rostov Scythians were primarily descended from Mesolithic West Eurasians or even Bronze Age ones, then we would expect them to cluster at the "top", approaching the northern Europeoid extrema of PWC and Bronze Age Altai (ALT-BA). On the contrary, their position is well to the "south" of all European Bronze Age groups, and intermediate between Europeans and Iron Age Asian groups from south Siberia and Kazakhstan (KUR-IA, KAZ-IA). Again, this is compatible with an east-west migration during the Iron Age.

It might be worth speculating on the possible autosomal history of the steppe, for which the mtDNA evidence complements others: I offer that the long-term trend will be one of diminishing "North European", increasing "West Asian" and "East Eurasian" influences across the Neolithic-Bronze-Iron Age boundaries. At the western end of the steppe, there may also be "Mediterranean"/Sardinian-like infusions from the Balkans and Central Europe, although these clearly did not influence Inner/South Asia (where Mediterranean components shrink to non-existence), and Europe proper was mostly the recipient rather than the emitter of populations to Asia. Hopefully, autosomal data to test this conjecture will be made available in the coming years.

Mitochondrial DNA in Ancient Human Populations of Europe (der Sarkissian 2011)

Going over the 322 pages of thesis may take a while, but feel free to comment on it if you discover any interesting nuggets in the text. The following view of West/East Eurasian mtDNA surrounding the beginning of the Iron Age may be useful, and seems to parallel the results of a recent paper on Pazyryk mtDNA:

Of course, since the thesis was published we have new data from West Siberia/Ukraine that suggest that the penetration of east Eurasian lineages covered a great area to the west of the indicated region even prior to the Iron Age.

We can be fairly sure that "non-East Eurasian admixed" populations existed during the Bronze Age in three portions of the Eurasian landmass, separated by the Black and Caspian Seas: west of the Black Sea (Balkans/Central Europe); between Black and Caspian Seas (Caucasus) and east of the Caspian Sea (Kazakhstan and Turkmenistan). But how did these three regions contribute to the West Eurasian elements found on a west-east axis across Eurasia today? And, to what extent did the early east Eurasian elements that penetrated well into eastern Europe in the Neolithic-to-Bronze Age contribute to latter populations of the area vs. more recent expansions from the Altai and Central Asia during the Iron Age?

Here is a PCA of the pre-Iron Age individuals, compared with modern populations:

Both "Tarim" (TAR) and "Neolithic Lake Baikal" (LOK) appear well within east Eurasian variation. But, of the West Eurasian groups, Pitted Ware Complex (PWC), i.e., Neolithic hunter-gatherers from NE Europe and Bronze Age Altai (ALT-BA) appear clearly "northern Europeoid" across the 2nd PC, as do, to a lesser extent, C/N European Hunter-Gatherers (HG) and Kurgan burials from south Siberia (KUR-BA), but Bronze Age Kazakhstan (KAZ-BA) appear to be southern Europeoid, and, also, noticeably more "West Eurasian" than the others. Clearly, the West Eurasian elements were not homogeneous, with some of them (such as KAZ-BA) apparently derived from the southern Caucasoid zone -which largely did not experience east Eurasian admixture- and others from the northern Caucasoid zone that did.

The Rostov Scythian sample (in red) appears to belong to the southern Caucasoid zone (across PC2), but East Eurasian-shifted relative to modern Europeans and Bronze Age Kazakhstan.

Now, let's look at the Iron and post-Iron Age samples:

Egyin Gol (EG) from Mongolia and Sargat Siberians appear clearly as East Eurasians; Pazyryk Altai (ALT-IA), Iron Age Kazakhstan (KAZ-IA) and South Siberia Kurgan (KUR-IA) show decreasing East Eurasian influence; also notice the decidedly "southern" shift of the West Eurasian element among them.

This seems broadly consistent with the ideas of Molodin et al. about the gradual appearance (in their Siberian sample) of Caucasoid mtDNA types from the Neolithic to the Iron Age, with the early Neolithic U-dominated population finally receiving a full set of diverse West Eurasian lineages only during the Iron Age from the south.

It will certainly be very exciting when samples such as these can be tested for autosomal or Y-chromosome DNA, and I'm looking forward to the day when this can be done on a large scale.

Type: Thesis
Title: Mitochondrial DNA in ancient human populations of Europe.
Author: Dersarkissian, Clio Simone Irmgard
Issue Date: 2011
School/Discipline: School of Earth and Environmental Sciences

Abstract: The distribution of human genetic variability is the result of thousand years of human evolutionary and population history. Geographical variation in the nonrecombining maternally inherited mitochondrial DNA has been studied in a wide array of modern populations in order to reconstruct the migrations that have participated in the spread of our ancestors on the planet. However, population genetic processes (e.g., replacement, genetic drift) can significantly bias the reconstruction and timing of past migratory and demographic events inferred from the analysis of modern-day marker distributions. This can lead to erroneous interpretations of ancient human population history, a problem that potentially could be circumvented by the direct assessment of genetic diversity in ancient humans. Despite important methodological problems associated with contamination and post-mortem degradation of ancient DNA, mitochondrial data have been previously obtained for a few spatially and temporally diverse European populations. Mitochondrial data revealed additional levels of complexity in the population history of Europeans that had remained unknown from the study of modern populations. This justifies the relevance of broadening the sampling of ancient mitochondrial DNA in both time and space. This study aims at filling gaps in the knowledge of the genetic history of eastern Europeans and of European genetic outliers, the Saami and the Sardinians. This study presents a significant extension to the knowledge of past human mitochondrial diversity. Ancient remains temporally-sampled from three groups of European populations have been examined: north east Europeans (200 – 8,000 years before present; N = 76), Iron Age Scythians of the Rostov area, Russia (2,300 – 2,600 years before present; N = 16), Bronze Age individuals of central Sardinia, Italy (3,200 – 3,400 years before present; N = 16). The genetic characterisation of these populations principally relied on sequencing of the mitochondrial control region and typing of single nucleotide polymorphisms in the coding region. Changes in mitochondrial DNA structure were tracked through time by comparing ancient and modern populations of Eurasia. Analysis of haplogroup data included principal component analysis, multidimensional scaling, fixation index computation and genetic distance mapping. Haplotypic data were compared by haplotype sharing analysis, phylogenetic networks, Analysis of the Molecular Variance and coalescent simulations. The sequencing of a whole mitochondrial genome in a north east European Mesolithic individual lead to defining a new branch within the human mitochondrial tree. This work presents direct evidence that Mesolithic eastern Europeans belonged to the same Palaeolithic/Mesolithic genetic background as central and northern Europeans. It was also shown that prehistoric eastern Europeans were the recipients of multiple migrations from the East in prehistory that had not been previously detected and/or timed on the basis of modern mtDNA data. Ancient DNA also provided insights in the genetic history of European genetic outliers; the Saami, whose ancestral population still remain unidentified, and the Sardinians, whose genetic differentiation is proposed to be the result of mating isolation since at least the Bronze Age. This study demonstrates the power of aDNA to reveal previously unknown population processes in the genetic history of modern Eurasians.

Link

More on prehistoric South Siberians (Keyser et al. 2009)

This seems like a compendium of these authors' previous work (see here and links therein) which had appeared in forensic journals so far; there seems to be more material in this paper than in the previous shorter papers, but as far as I can tell, no new genetic results.

There is also supplementary data in the article.

From the paper:

The additional analysis performed on Xiongnu specimens revealed that whereas none of the specimens from the Egyin Gol valley bore this haplogroup, the Scytho-Siberian skeleton from the Sebÿstei site exhibited R1a1 haplogroup.

A previous study on Egyin Gol from Mongolia by Keyser et al.

More from the paper:

A search in the YHRD database as well as in our own databank revealed that none of the Y-STR haplotypes obtained from the south Siberian samples perfectly matched (at 17 loci) those included in the databases. Nevertheless, when not all loci were scored, matches were found for all samples except two (S07 and S32) for which even the search based on the 9-loci minimal haplotype was fruitless (Table 4).

The article includes fairly comprehensive searches of the discovered Y-chromosome and mtDNA types in modern populations.

The mtDNA results:

Twenty samples were found to belong to west Eurasian haplogroups (U2, U4,
U5a1, T1, T3, T4, H5a, H6, HV, K, and I), whereas the 6 remaining samples were attributed to east Eurasian haplogroups (Z, G2a, C, F1b and N9a).

Interestingly:

Moreover, it is likely that some mtDNA lineages were carried to southern Siberia from the Volga–Ural region. Incidentally, in the fifth century BC, Herodotus mentioned transit trade occurring in Central Asia along a route that stretched from the Urals in the west to the Altai and the Minusinsk Basin in the east (Hemphill and Mallory 2004). In Altai, the presence of the R1a1 haplogroup in the middle of the fifth century BC is confirmed by the sample SEB 96K2 of Ricaut et al. (2004) which was found to belong to this Y-haplogroup. The boundary of the eastern European influence seems to be fixed at the peri-Baikal area since no R1a1 haplogroup was found in the Xiongnu specimens of the Northern border of Mongolia.

Link to Ricaut et al. (2004). This is in good agreement with the anthropological picture by Alexeev:

"The boundary of the Europeoid movement is clearly fixed at Lake Baikal. To the east of Baikal no palaeoanthropological find bears any traces of Europeoid admixture."

See also my compendium on ancient Y-chromosome studies.

Human Genetics doi:10.1007/s00439-009-0683-0

Ancient DNA provides new insights into the history of south Siberian Kurgan people.

Keyser C. et al.

Abstract

To help unravel some of the early Eurasian steppe migration movements, we determined the Y-chromosomal and mitochondrial haplotypes and haplogroups of 26 ancient human specimens from the Krasnoyarsk area dated from between the middle of the second millennium BC. to the fourth century AD. In order to go further in the search of the geographic origin and physical traits of these south Siberian specimens, we also typed phenotype-informative single nucleotide polymorphisms. Our autosomal, Y-chromosomal and mitochondrial DNA analyses reveal that whereas few specimens seem to be related matrilineally or patrilineally, nearly all subjects belong to haplogroup R1a1-M17 which is thought to mark the eastward migration of the early Indo-Europeans. Our results also confirm that at the Bronze and Iron Ages, south Siberia was a region of overwhelmingly predominant European settlement, suggesting an eastward migration of Kurgan people across the Russo-Kazakh steppe. Finally, our data indicate that at the Bronze and Iron Age timeframe, south Siberians were blue (or green)-eyed, fair-skinned and light-haired people and that they might have played a role in the early development of the Tarim Basin civilization. To the best of our knowledge, no equivalent molecular analysis has been undertaken so far.

Link

iGENEA wins an award

... the newly instituted Anthropology Blog award for Outstanding Achievement in Misleading the Public about Human Population Genetics.

I don't usually post about specific genetic testing companies unless they do something innovative, but I got two e-mails recently about a particular company, and I have to make an exception.

First of all, let me state that I have no reason to doubt that their genetic testing results (i.e., the actual Y-STR values) are accurate. What I do have a problem with is the copious amount of misleading information provided in their website (as of Oct 16, 2008). 

You will learn for example that there is no haplogroup N in Finland, that there is 30% R1b in Russia, 5% of haplogroup J in Armenia, but 10% in Germany. You will also be pleased to know that Y-chromosome haplogroup J is associated with the  Jews and mtDNA haplogroup H with the Vikings. But, wait, haplogroup I1a is associated with the Scythians [absent in most of Siberia and Central Asia but who cares about details], while mtDNA haplogroup H with the Teutons.

If you have time to kill, browse around the site, it is priceless as entertainment, and don't forget to stop by this thread where the company not only asserts that Y-chromosomes of ancient Greeks and Macedonians have been tested, pointing to completely irrelevant bibliography, as "evidence", but also lists the percentages of various ancient tribes in modern nations. Apparently, Bulgarians are 49% Thracian, while Albanians 18%, whereas Greeks and "Macedonians" 0%. Those Thracians must have evacuated from Greek Thrace and flown over Macedonia to settle in Albania :)

If you have any understanding of population genetics, no more needs to be said. 

But, if you are a newbie researching the field, spend some time to educate yourself, and don't trust companies that offer you the sky. If it's too good to be true, it probably isn't.

Life on horseback and skeletal pathology

This is precisely the type of skeletal evidence that advocates of early horseback riding should seek.

International Journal of Osteoarchaeology

Life on horseback: palaeopathology of two Scythian skeletons from Alexandropol, Ukraine

R. K. Wentz et al.

Abstract

In 2006, two skeletons were analysed that were previously excavated from the periphery of a Scythian burial mound, near the village of Alexandropol in southern Ukraine. Dated to ca. 325 BC, both remains are male. The first is that of a youth in his late teens who exhibits indications of biological stress and degenerative changes to the spine in the form of a Schmorl's node. The second is a middle-aged individual with extensive healed lesions due to trauma to the right humerus and clavicle with associated bony changes of the elbow and spine. Stable isotope analyses indicate a diet based on C3 plants. Their skeletons suggest a rigorous life on horseback. Both may have served as sacrificial victims. Historical records document the strangulation of attendants and their placement around the periphery of royal burial mounds. Grave goods suggest that both were warriors, although the youth lacks the traumatic injuries exhibited by the older male. The individuals from Alexandropol may have served a Scythian king in life and in death.

Link

Scythians of the North Pontic region

Archaeology, Ethnology, and Anthropology of Eurasia, vol. 4 (32), 2007, pp. 143-157

SCYTHIANS OF THE NORTH PONTIC REGION: BETWEEN-GROUP CRANIAL VARIATION, AFFINITIES, AND ORIGINS

A.G. Kozintsev

(no abstract)

"First of all, the variation between the Scythian groups must be assessed in order to compare it with the total variation. The average distance between all the 22 Scythian groups is 6.30; that between the 17 steppe groups, 5.25; that between the five forest-steppe groups, 5.88; and that between the steppe and the forest-steppe groups, 8.04. As will be seen below, these values are not at all small by the general standard."

...

"Our results agree with the conclusions made by A.Yu. Alekseyev (1993), who speaks of two Scythian cultures, separated by a sharp gap: one archaic, distributed mostly in the forest-steppe and in the northern Caucasus, another classical, distributed in the steppe. It appears reasonable to assume that the two cultures were associated with tribes differing in origin, and that the term “Scythians” can be used with regard to the forest-steppe people only in a broad sense."

...

"Therefore, contrary to a widely held belief, which, until quite recently, was shared by all physical anthropologists, not a single biological fact (at least insofar as craniometry is concerned) suggests that the only, or at least the principal ancestors of the steppe Scythians were people of the Timber-grave culture. Now that this culture is represented by numerous populations from various parts of its distribution area, the above statement can be made with certainty not only with regard to the steppe Scythians in general, but also with regard to the vast majority of local steppe populations as well."

...

"The hypothesis formulated by Kovalev (see above) does not contradict the fact that gracilization began in the southern part of the Caucasoid distribution range. At the same time, this hypothesis agrees with the theory of two Indo-European homelands – the early one, Near Eastern, and the late one, European, situated in regions from the Balkans (Diakonov, 1982) to Central or even Northern Europe (Safronov, 1989; Klein, 1990 and in print), i.e., areas covered by the depigmentation process."

...

"Craniometrical findings indirectly support the theory that the forest-steppe Scythians were autochthonous. Both for this group as a whole and for its local populations, including the earliest one, from Medvin, the most distinct ties are those with people of the Timber-grave culture of the Ukraine, especially with the group from the ground burials of that culture. No less relevant are ties with the Belozerskaia group. The isolated position of certain forest-steppe Scythian groups, which reveal no ties with other populations, may point to a key role of microevolutionary (especially random) processes.

4. Parallels between the steppe Scythians and people of the Timber-grave culture evidently do not attest to the local origin of the former. They are less distinct than parallels with earlier Bronze Age populations (those associated with the Pit-grave and Catacomb cultures) and therefore point not so much to the local roots of the steppe Scythians as to the fact that their ancestors were Indo-Europeans (most likely Indo-Iranians), some groups of which migrated during the Bronze Age as far east as Eastern Central Asia. The return of their descendants to the North Pontic steppes in the Early Iron Age was apparently the key factor in the origin of the steppe Scythians (at least of the relatively late populations represented in our database)."

The spread of tuberculosis

Genghis Khan's previous claim to genetic fame was linked to the presence in about 0.5% of the population of the entire world and in a substantial portion of the population of Central Asia, of a unique Y-chromosome haplotype.

Now, a team of geneticists led by Igor Mokrusov are uncovering the darker aspects of the Great Khan's conquests. From their press release.

Mokrousov's team hypothesized that, given the strong gender bias of TB infectivity and the likely family-based mode of TB transmission during pre-industrialized times, M. tuberculosis dissemination has reflected the unidirectional inheritance of the paternally transmitted human Y chromosome. To test this hypothesis, the authors compared the genetic profiles of a common form of M. tuberculosis, called the Beijing genotype, with known patterns of prehistoric and recent human migrations, as well as with global patterns of Y-chromosome variation. Strikingly, they observed that over the past 60,000-100,000 years, the dispersal and evolution of M. tuberculosis appears to have precisely ebbed and flowed according to human migration patterns.

The authors describe how the Beijing genotype of M. tuberculosis originated in a specific human population called the K-M9 in central Asia approximately 30,000-40,000 years ago following a second "out of Africa" migration event. The bacteria and its human host then disseminated northeast into Siberia between 20,000-30,000 years ago and throughout eastern Asia between 4,000-10,000 years ago. More recently, the Beijing genotype of M. tuberculosis was introduced into northern Eurasia, perhaps by Genghis Khan himself during the 1200's, and into South Africa, possibly through sea trade contacts with Indonesia or China during the last 300 years.

Please note that while most news will doubtlessly focus on the Genghis Khan angle, the spread of haplogroup K-M9 occurred in deep prehistory. Only much later did a a particular genotype of M. tuberculosis spread, perhaps by the actions of Genghis Khan, although there have been multiple incursions of Mongoloid peoples which may account for the current distribution, and as the authors note, its introduction into South Africa was an independent event.

UPDATE

I have finished reading the paper, and the argument that the authors make for the introduction of the variant in Europe by the armies of Genghis Khan is quite ingenuous:

Since the Beijing genotype is not a European endemic variant, the published PC analysis of European human populations allows us to rule out those migrations that equally concerned both Russia and Europe as sources of the Beijing strains. These are defined by Finno-Ugric (PC2) (Cavalli-Sforza 2001), Scythe (PC3) (Cavalli-Sforza 2001), and Hun (Christian 1998) expansions. We may further speculate that trade contacts as such, even long-lasting ones, are not sufficient for an effective dissemination of the M. tuberculosis strains if they are not supported by a kind of demic diffusion of the strains’ carriers, manifested as population growth and migration. The Silk Road connected China with Europe for almost two millennia, 2 BC–1600 AD (Christian 1998), and this route may have been opened much earlier, based on the transfer of the first ceramics technology from Japan to the Middle East and Europe at the beginning of agricultural practice (Cavalli-Sforza 2001). However, it is appropriate to reiterate that Beijing strains are not identified as a European endemic variant.

Finally, we suggest the TB spread related to the Genghis (or Chinggiz) Khan invasion to be more plausible. The Mongol empire of the 13th century brought the different parts of Eurasia closer than they had ever been before and created an economic and cultural system embracing much of the Eurasian land mass (Christian 1998). It was also a period of remarkable ethnic mixing since the Mongol army grew by incorporating the armies of many different nations that it had defeated, including Han Chinese (Christian 1998). McNeill (1976) suggested that Mongol invasions also unified Eurasia epidemiologically, allowing the exchange of the disease vectors throughout Eurasia. Genghis Khan did eventually come in the center of Europe, but for a short time. This was sufficient for the dissemination of Yersinia pestis to occur, but not for that of the far less contagious M. tuberculosis. Even if some M. tuberculosis Beijing genotype strains had been brought to Europe in this way, this may not have manifested rapidly. Subsequently, the Black Death that decimated European human populations could have efficiently eliminated rare carriers of the M. tuberculosis Beijing genotype. By contrast, further close interaction between Rus’ and Orda was prolonged for three centuries, and it may be possible that the Mongol invasion and the subsequent yoke/cohabitation were indeed the vehicle that brought M. tuberculosis Beijing genotype strains to Russia

The authors are noting that there have been multiple movements of peoples from Asia to Europe. So, how do they conclude that the Mongols of Genghis Khan are implicated? If the genotype was brought e.g., by the Huns, or the Scythians, or the Finno-Ugrians, then we would expect to find it commonly in Europe, because these movements affected large parts of the continent. But, the Beijing haplotype is not a European variant, so by a process of elimination these movements are probably not responsible for its dissemination.

Rather, it is the Mongols who held Russia -but not Europe- captive for three centuries, and Russia is the country in Europe where the Beijing genotype is found. Moreover, since the Mongols recruited soldiers from China, they could have acquired the genotype, and then brought it to Russia. It is then during the centuries of Mongol domination, at the western edge of Mongol expansion that the Beijing genotype was brought to Russia.

Genome Research

Origin and primary dispersal of the Mycobacterium tuberculosis Beijing genotype: Clues from human phylogeography

Igor Mokrousov et al.

Abstract

We suggest that the evolution of the population structure of microbial pathogens is influenced by that of modern humans. Consequently, the timing of hallmark changes in bacterial genomes within the last 100,000 yr may be attempted by comparison with relevant human migrations. Here, we used a lineage within Mycobacterium tuberculosis, a Beijing genotype, as a model and compared its phylogeography with human demography and Y chromosome-based phylogeography. We hypothesize that two key events shaped the early history of the Beijing genotype: (1) its Upper Palaeolithic origin in the Homo sapiens sapiens K-M9 cluster in Central Asia, and (2) primary Neolithic dispersal of the secondary Beijing NTF::IS6110 lineage by Proto-Sino-Tibetan farmers within east Asia (human O-M214/M122 haplogroup). The independent introductions of the Beijing strains from east Asia to northern Eurasia and South Africa were likely historically recent, whereas their differential dissemination within these areas has been influenced by demographic and climatic factors.

Link

Spread of the Scythians after c. 850BC

A new paper proposes that reduced solar activity after 850BC resulted in the transformation of formerly desert-like regions into herbivore-friendly wet steppes. According to this theory, the Scythian culture expanded after this time, taking advantage of the newly created steppe regions.

Journal of Archaeological Science
Article in Press, Corrected Proof
doi:10.1016/j.jas.2004.05.004

Climate change and the expansion of the Scythian culture after 850 BC: a hypothesis

B. van Geel et al.

Abstract

In south-central Siberia archaeological evidence suggests an acceleration of cultural development and an increase in the density of nomadic populations around 850 BC. We hypothesize a relationship with an abrupt climatic shift towards increased humidity caused by a decline of solar activity. Areas that initially may have been hostile semi-deserts changed into attractive steppe landscapes with a high biomass production and high carrying capacity. Newly available steppe areas could be invaded by herbivores, making them attractive for nomadic tribes. The central Asian horse-riding Scythian culture expanded, and an increased population density was a stimulus for westward migration towards southeastern Europe.

Link