Mitogenomes show Longobard migration was socially stratified and included females

antiquity-germanic-migrations

New bioRxiv preprint A genetic perspective on Longobard-Era migrations, by Vai et al. (2018).

Interesting excerpts (emphasis mine):

In this study we sequenced complete mitochondrial genomes from nine early-medieval cemeteries located in the Czech Republic, Hungary and Italy, for a total of 87 individuals. In some of these cemeteries, a portion of the individuals are buried with cultural markers in these areas traditionally associated with the Longobard culture (hereby we refer to these cemeteries as LC), as opposed to burial communities in which no artifacts or rituals associated by archaeologists to Longobard culture have been found in any graves. These necropolises, hereby referred as NLC, may represent local communities or other Barbaric groups previously migrated to this region. This extended sampling strategy provides an excellent condition to investigate the degree of genetic affinity between coeval LC and NLC burials, and to shed light on early-medieval dynamics in Europe.

lombard-hungary-czech
Geographical and genetic relationship between the newly sequenced individuals. (A) Location of the sampled necropolises. Here and through the other figures LC cemeteries are represented by a circle while NLC ones are indicated by a square. C) DAPC Scatterplot of the most supported K (7) highlighted by the kmeans analysis

Social rank

There is also no clear geographical structure between samples in our dataset, with individuals from Italy, Hungary and Czech Republic clustering together. However, the first PC clearly separates a group of 12 LC individuals found at Szólád, Collegno and Mušov from a group composed by both LC and NLC individuals. The same pattern is also found when pairwise differences among individuals are plotted by multidimensional scaling (…)

The presence in this group of LC sequences belonging to macrohaplogroups I and W, commonly found at high frequencies in northern Europe (e.g. Finland 32), suggests (although certainly does not prove) the existence of a possible link between these 12 LC individuals and northern Europe. The peculiarity of this group is strengthened by archaeological information from the Szólád cemetery, where 8 of the 12 individuals in this group originated, indicating that all these samples were found buried with typical Longobard artifacts and grave assemblages. We do not find the same tight association for the 3 samples from Collegno, where the 3 graves are indeed devoid of evident Germanic cultural markers; however they are not placed in a separate and marginal location—as for the tombs without grave goods found in Szólád —but among graves with wooden chambers and weapons. It is worth noting that weapon burials were quite scarce in 5th century Pannonia and 6th century Italy (e.g. Goths never buried weapons), and an increase in weapon burials started in Italy only after the Longobard migration. In this light, the individuals buried in this manner may have been members of the same community as well, but belonging to the lowest social level. This social condition could explain the absence of artifacts and could be related to mixed marriages, whose offspring had an inferior social rank. Finally, this group also includes an individual from the Musov graveyard. This finding is particularly interesting in light of the fact that the Musov necropolis has been only tentatively associated with Longobard occupation (see Supplementary Text for details), based on the presence of but a few archaeological markers.

Female migration

We hence estimated that about 70% of the lineages found in Collegno actually derived from the Hungarian LC groups, in agreement with previous archaeological and historical hypotheses. This supports the idea that the spread of Longobards into Italy actually involved movements of fairly large numbers of people, who gave a substantial contribution to the gene pool of the resulting populations. This is even more remarkable thinking that, in many studied cases, military invasions are movements of males, and hence do not have consequences at the mtDNA level. Here, instead, we have evidence of changes in the composition of the mtDNA pool of an Italian population, supporting the view that immigration from Central Europe involved females as well as males.

Related

When Bell Beakers mixed with Eneolithic Europeans: Pömmelte and the Europe-wide concept of sanctuary

pommelte-enclosure

Recent open access paper The ring sanctuary of Pömmelte, Germany: a monumental, multi-layered metaphor of the late third millennium BC, by Spatzier and Bertemes, Antiquity (2018) 92(363):655-673.

Interesting excerpts (emphasis mine):

In recent decades, evidence has accumulated for comparable enclosures of later dates, including the Early Bronze Age Únětice Culture between 2200 and 1600 BC, and thus into the chronological and cultural context of the Nebra sky disc. Based on the analysis of one of these enclosure sites, recently excavated at Pömmelte on the flood plain of the Elbe River near Magdeburg, Saxony-Anhalt, and dating to the late third millennium BC

The main occupation began at 2321–2211 cal BC, with the stratigraphically earliest features containing exclusively Bell Beaker finds. Bell Beaker ceramics continue after 2204–2154 cal BC (boundary occupation I/II), although they were probably undecorated, but are now complemented by Únětice Culture (and other Early Bronze Age) types. At this time, with features common to both cultures predominate. Only contexts dating to the late main occupation phase (late phase II) and thereafter contained exclusively Únětice Culture finds. Evidently, the bearers of the Bell Beaker Culture were the original builders of the enclosure. During a second phase of use, Final Neolithic and Early Bronze Age cultures coexisted and intermingled. The material remains, however, should not be taken as evidence for successive groups of differing archaeological cultures, but as witnesses to a cultural transition from the Bell Beaker Culture to the Únětice Culture (Spatzier 2015). The main occupation ended 2086–2021 cal BC with the deconstruction of the enclosure; Bell Beaker finds are now absent. Finally, a few features (among them one shaft) and radiocarbon dates attest the sporadic re-use of the site in a phase of abandonment/re-use that ended 1636– 1488 cal BC.

pommelte-enclosure-occupation-stratigraphy
Cultural sequence and chronological model of the Pömmelte enclosure’s occupation (dates in 1σ-precision) (designed by André Spatzier).

How the above-ground structures possibly influenced perception may reveal another layer of meaning that highlights social functions related to ritual. While zone I was disconnected from the surroundings by a ‘semi-translucent’ post-built border, zones II/III were separated from the outside world by a wooden wall (i.e. the palisade), and zone III probably separated individuals from the crowd gathered in zone II. Accessing the interior or centre therefore meant passing through transitional zones, to first be secluded and then segregated. Exiting the structure meant re-integration and re-connection. The experience possibly induced when entering and leaving the monument reflects the three stages of ‘rites of passage’ described by van Gennep (1909): separation, liminality and incorporation. The enclosure’s outer zone(s) represents the pre- and post-liminal phase; the central area, the liminal phase. Seclusion and liminality in the interior promoted a sense of togetherness, which can be linked to Turner’s “communitas” (1969: 132–33). We might therefore see monuments such as the Pömmelte enclosure as important communal structures for social regulation and the formation of identity.

ring-sanctuary-of-pommelte
Layers of meaning of the Pömmelte enclosure as deduced from the archaeological record (design by André Spatzier).

(…) The long-term stability of these connotations must be emphasised. As with the tradition of making depositions, these meanings were valid from the start of the occupation — c. 2300 BC — until at least the early period following the deconstruction event, c. 2050 BC. While the spatial organisation and the solar alignment of the main entrances were maintained throughout the main occupation, stone axes and ‘formal’ graves indicate the continuation of the spatial concepts described above until the twentieth to nineteenth centuries BC.

These layers of meaning mirror parallel concepts of space including, although not necessarily restricted to, the formation of group identities (see Hansen & Meyer 2013: 5). They can perhaps be better understood as a ‘cosmological geography’ manifested in the symbolism of superimposed levels of conceptual ideas related to space and to certain cardinal points (Figure 8). This idea is closely related to Eliade’s (1959: 29–36) understanding of “organized — hence comicized — territory”, that is territory consecrated to provide orientation within the homogeneity of the chaotic ‘outside world’, and the equivalence of spatial consecration and cosmogony. Put differently, the Pömmelte enclosure can be interpreted as a man-made metaphor and an icon of the cosmos, reflecting the Weltanschauung (a comprehensive conception of the world) of the people who built and used it. By bringing together Eliade and Rappaport’s ideas of meaningfulness in relation to religious experience (Rappaport 1999: 391–95), it may be argued that Pömmelte was a place intended to induce oneness with the cosmos. In combining multiple layers that symbolically represent different aspects of life (first-ordermeaning), the enclosure became an icon metaphorically representing the world (second-order-meaning). As this icon was the place to reaffirm life symbolism ritually, through their actions, people perhaps experienced a sense of rootedness in, or unity with, the cosmos (highest-order-meaning). Although we can only speculate about the perceptions of ancient people, such a theory aiming to describe general principles of religious experience can provide insight.

Conclusions

The circular enclosure of Pömmelte is the first Central European monumental complex of primarily sacred importance that has been excavated and studied in detail. It reveals aspects of society and belief during the transition from the Final Neolithic to the Early Bronze Age, in the second half of the third millennium BC. Furthermore, it offers details of ritual behaviour and the way that people organised their landscape. A sacred interior was separated from the profane environment, and served as a venue for rites that secured the continuity of the social, spiritual and cosmic order. Ancestor worship formed another integral part of this: a mound-covered burial hut and a square-shaped ditch sanctuary (located, respectively, within and near the enclosure’s south-eastern sector; cf. Figure 2)—dating to 2880–2580 cal BC and attributed to the Corded Ware Culture (Spatzier 2017a: 235–44)—suggest that this site was deliberately chosen. With construction of the ring sanctuary, this place gained an immense expansion in meaning—comparable to Stonehenge. Through architectural transformation, both of these sites developed into sanctuaries with increasingly complex religious functions, including in relation to the cult of the dead. The cosmological and social functions, and the powerful symbolism of the Nebra sky disc and hoard (Meller 2010: 59–70), are reflected in Pömmelte’s monumental architecture.

All of these features—along with Pömmelte’s dating, function and complex ring structure—are well documented for British henge monuments (Harding 2003; Gibson 2005). The continuous use of circular enclosures in Central Europe from around 3000– 1500 BC remains to be confirmed, but strong evidence indicates usage spanning from the fifth to the first millennia BC (Spatzier 2017a: 273–96). From 2500 BC onwards, examples in Central Europe, Iberia and Bulgaria (Bertemes 2002; Escudero Carrillo et al. 2017) suggest a Europe-wide concept of sanctuary. This indicates that in extensive communication networks at the beginning of bronze metallurgy (Bertemes 2016), intellectual and religious contents circulated alongside raw materials. The henge monuments of the British Isles are generally considered to represent a uniquely British phenomenon, unrelated to Continental Europe; this position should now be reconsidered. The uniqueness of Stonehenge lies, strictly speaking, with its monumental megalithic architecture.

pommelte-enclosure-space
Model of the spatial organisation of the Pömmelte enclosure (designed by André Spatzier).

The Classical Bell Beaker heritage

No serious scholar can argue at this point against the male-biased East Bell Beaker migrations that expanded the European languages related to Late Proto-Indo-European-speaking Yamna (see David Reich’s comments), and thus most likely North-West Indo-European – the ancestor of Italo-Celtic, Germanic, and Balto-Slavic, apart from Pre-Celtic IE in the British Isles, Lusitano-Galician in Iberia, or Messapic in Italy (see here a full account).

With language, these migrants (several ten thousands) brought their particular Weltanschauung to all of Western, Central, and Northern Europe. Their admixture precisely in Hungary shows that they had close interactions with non-Indo-European peoples (genetically related to the Globular Amphorae culture), something that we knew from the dozens of non-Indo-European words reconstructed exclusively for North-West Indo-European, apart from the few reconstructed non-Indo-European words that NWIE shares with Palaeo-Balkan languages, which point to earlier loans from their ancestors, Yamna settlers migrating along the lower Danube.

It is not difficult to imagine that the initial East Bell Beaker group shared a newly developed common cosmological point of view that clashed with other neighbouring Yamna-related worldviews (e.g. in Balkan EBA cultures) after the cultural ties with Yamna were broken. Interesting in this respect is for example their developed (in mythology as in the new North-West Indo-European concept) *Perkwūnos, the weather god – probably remade (in language as in concept) from a Yamna minor god also behind Old Indian parjányas, the rain god – as one of the main gods from the new Pantheon, distinct from *Dyēus patēr, the almighty father sky god. In support of this, the word *meldh-n- ‘lightning’, behind the name of the mythological hammer of the weather god (cf. Old Norse Mjǫllnir or Latvian Milna), was also a newly coined North-West Indo-European term, although the myth of the hero slaying the dragon with the magical object is older.

perkunos-perkunas
The Hand of Perkūnas by Mikalojus Konstantinas Čiurlionis, from Wikipedia

Circular enclosures are known in Europe since the Neolithic. Also, the site selected for the Pömmelte enclosure had been used to bury Corded Ware individuals some centuries before its construction, and Corded Ware symbolism (stone axe vs. quern) is seen in the use given by Bell Beakers and later Únětice at this place. All this and other regional similarities between Bell Beakers and different local cultures (see here an example of Iberian Bell Beakers) points to syncretism of the different Bell Beaker groups with preceding cultures in the occupied regions. After all, their genealogical ancestors included also those of their maternal side, and not all encountered males disappeared, as is clearly seen in the resurge of previous paternal lineages in Central-East Europe and in Scandinavia. The admixture of Bell Beakers with previous groups (especially those of similar steppe-related ancestry from Corded Ware) needs more complex analyses to clarify potential early dialectal expansions (read what Iosif Lazaridis has to say).

The popular “big and early” expansions

These syncretic trends gave rise to distinct regional cultures, and eventually different local groups rose to power in the new cultural regions and ousted the old structures. Social norms, hierarchy, and pantheons were remade. Events like this must have been repeated again and again in Bronze and Iron Age Europe, and in many cases it was marked by a difference in the prevailing archaeological culture attested, and probably accompanied by certain population replacements that will be seen with more samples and studies of fine-scale population structure.

Some of these cultural changes, marked by evident haplogroup or admixture replacement, are defined as a ‘resurge’ of ancestry linked to previous populations, although that is obviously not equivalent to a resurge of a previous cultural group, because they usually represent just a successful local group of the same supraregional culture with a distinct admixture and/or haplogroup (see e.g. resurge of R1a-Z645 in Central-East European Bronze Age). Social, religious, or ethnic concepts may have changed in each of these episodes, along with the new prestige dialect.

NOTE. A recent open access paper on two newly studied Middle Bronze Age inhumations from Stonehenge give an interesting idea of potential differences in social identities, in ancestry and geographic origin (which characterize ethnicity) may have been marked by differences in burial ceremonies: Lives before and after Stonehenge: An osteobiographical study of four prehistoric burials recently excavated from the Stonehenge World Heritage Site, by Mays et al. Journal of Archaeological Science: Reports (2018) 20:692-710.

This must have happened then many times during the hundreds (or thousands in some cases) of years until the first attestation of a precise ancient language and culture (read e.g. about one of the latest branches to be attested, Balto-Slavic). Ancient language contacts, like substrates or toponymy, can only rarely be detected after so many changes, so their absence (or the lack of proper studies on them) is usually not relevant – and certainly not an argument – in scholarly discussions. Their presence, on the other hand, is a proof of such contacts.

chalcolithic_late_Europe_Bell_Beaker
Diachronic map of Late Copper Age migrations including Classical Bell Beaker (east group) expansion from central Europe ca. 2600-2250 BC

We have dozens of papers supporting Uralic dialectal substrate influence on Pre-Germanic, Proto-Balto-Slavic, and Pre- and Proto-Indo-Iranian (and even Proto-Celtic), as well as superstrate influence of Palaeo-Germanic (i.e. from Pre- to Proto-Germanic) and Proto-Balto-Slavic into Proto-Finno-Saamic, much stronger than the Indo-Iranian adstrate influence on Finno-Ugric (see the relative importance of each influence) which locates all these languages and their evolution to the north and west of the steppe (with Proto-Permic already separated, in North-East Europe, as is Proto-Ugric further east near the Urals), probably around the Baltic and Scandinavia after the expansion of Bell Beakers. These connections have been known in linguistics for decades.

Apart from some early 20th century scholars, only a minority of Indo-Europeanists support nowadays an Indo-European (i.e. centum) substrate for Balto-Slavic, to keep alive an Indo-Slavonic group based on a hypothetical 19th century Satem group; so e.g. Holzer with his Temematic, and Kortlandt supporting him, also with some supposed Indo-European substrate with heavy non-Indo-European influence for Germanic and Balto-Slavic, that now (thanks mainly to the views of the Copenhagen group) have been linked to the Corded Ware culture, as it has become clear even to them that Bell Beakers expanded North-West Indo-European.

NOTE. The Temematic etymologies have been (all of them) fully dismissed e.g. in Matasović (2013). I have already explained why an Indo-Slavonic group from Sredni Stog is not tenable, and genetics (showing Late PIE only from Yamna expansions) is proving that, too.

For their part, only a minority among Uralicists, such as Kuz’mina, Parpola or Häkkinen, believe in an ‘eastern’ origin of Uralic languages, around the Southern Urals. Genomic finds – like their peers – are clearly not supporting their views. But even if we accept this hypothesis, there is little space beyond Abashevo and related East Corded Ware cultures after the recent papers on Corded Ware and Fennoscandian samples. And yet here we are:

The Copenhagen “Homeland” interactive map

copenhagen-group-map
Brought to you by the Copenhagen fantasy map series, Indo-Europeans after (no, really, after) the expansion of Yamna settlers in Hungary ca. 2700 BC: Yamna settlers have magically disappeared. Yamna-related Balkan EBA cultures and the hundreds of Yamna kurgans around the Lower Danube and in Hungary up to Saxony-Anhalt do not exist. Dat huge mythical Middle Dnieper territory lasting (unchanged) for a thousand years, in sooo close contact with Yamna territory (so beautifully ‘linked’ together that they must have been BFFs and admixed!). Uralic Mesolithic hunter-gatherers resisting IE invasions in Volosovo for 1,500 years like Asterix’ Gaulish village against the Romans. Tiny pockets of Bell Beakers will eventually emerge from (surprise!) Corded Ware territories beautifully scattered over Central and Northern Europe (unlike those eastern CWC mega-regions). And, of course, you can almost see Kroonen & Iversen’s Kurgan Pre-Germanic mixing already with their agricultural substrate TRB precisely in full-IE Denmark (quite appropriate for the Danish school). And sheep symbols representing wool finds, for no reason. A great map to mock for years to come, with each new genetic paper.

The new propaganda tool GIS timeline map of the Copenhagen group:

  • consciously ignores Yamna settlers along the Danube, in the Balkans, and in Hungary, and initial East Bell Beakers, i.e. the obvious origin and expansion of North-West Indo-Europeans, but in contrast magnifies (and expands in time) regions for Sredni Stog / Corded Ware cultures (which suggests that this is yet another absurd attempt to revive the theories of the Danish school…);
  • substitutes arrows for Kron-like colors (where danger red = Indo-European) with the same end result of many other late 20th century whole-Europe Kurgan maps, linking Sredni Stog and Corded Ware with Yamna, but obviating the precise origin of Corded Ware peoples (is it Sredni Stog, or is it that immutable Middle Dnieper group? is it West Yamna, or Yamna Hungary? is it wool, or is it wheels?);
  • relegates Uralic speakers to a tiny corner, a ‘Volosovo’ cultural region, thus near Khvalynsk/Yamna (but not too much), that miraculously survives surrounded by all-early-splitting, all-Northern Eneolithic Indo-Europeans, thus considering Uralic languages irrelevant not only to locate the PIE Urheimat, but also to locate their own homeland; also, cultures identified in color with Uralic speakers expand until the Iron Age with enough care not to even touch in the map one of the known R1a samples published to date (because, for some people, apparently R1a must be Indo-European); and of course N1c or Siberian ancestry are irrelevant, too;
  • and adds findings of wheels and wool probably in support of some new ideas based on yet another correlation = causation argument (that I cannot then properly criticize without access to its reasoning beyond cute SmartArt-like symbols) similar to their model – already becoming a classic example of wrong use of statistical methods – based on the infamously named Yamnaya ancestral component, which is obviously still used here, too.

The end result is thus similar to any other simplistic 1990s Gimbutas (or rather the recently radicalized IE Sredni Stog -> Corded Ware -> BBC version by the Danish workgroup) + 2000s R1a-map + 2010s Yamnaya ancestry; but, hard to believe, it is published in mid-2018. A lot of hours of senseless effort, because after its publication it becomes ipso facto outdated.

For comparison of Yamna and Bell Beaker expansions, here is a recent simplistic, static (and yet more accurate) pair of maps, from the Reich Lab:

corded-ware-bell-beaker
Cultural maps from Eneolithic and Chalcolithic cultures in Wang et al. (2018).

If the Copenhagen group keeps on pushing Gimbutas’ long ago outdated IE Sredni Stog -> Corded Ware theory as modified by Kristiansen, with their recently invented Corded Ware -> Bell Beaker model in genetics, at some point they are bound to clash with the Reich-Jena team, which seems to have less attachment to the classic Kurgan model and the wrong interpretations of the 2015 papers, and that would be something to behold. Because, as Cersei would say: “When you play the game of thrones, you win or you die. There is no middle ground.” And when you play the game of credibility, after so many, so wrong publications, well…

NOTE. I have been working on a similar GIS tool for quite some time, using my own maps and compiled genetic data, which I currently only use for my 2018 revision of the Indo-European demic diffusion model. Maybe within some weeks or months I will be able to publish the maps properly, after the revised papers. It’s a pitty that so much work on GIS and analysis with genetic data and cultural regions has to be duplicated, but I intend to keep some decent neutrality in my revised cultural maps, and this seems impossible at this point with some workgroups who have put all their eggs in one broken basket…

Related

Mitogenomes from the middle of the Merovingian period in the Lorraine region

herange-burial

Investigating the kinship between individuals deposited in exceptional Merovingian multiple burials through aDNA analysis: The case of Hérange burial 41 (Northeast France), by Deguilloux et al. Journal of Archaeological Science: Reports (2018) 20:784-790.

Interesting excerpts (emphasis mine):

The Merovingian period in Northeast France (developing from 440/450 to 700/710 CE; Legoux et al., 2004) represents [a case of multiple burial], where a large majority of the types of deposits encountered consists of individual burials. In this context, whereas hundreds of individual burials are known, the syntheses recently conducted have enabled the inventory of only six multiple burials (Lefebvre and Lafosse, 2016). These observations naturally raised questions about the exceptional circumstances that led the members of the community to set up such unusual burials. The archaeological site of Hérange, excavated in 2014 (Lorraine, Grand Est region; Fig. S1), holds a key position in the debate surrounding the interpretation of multiple burials during the Merovingian period since it contains one of these rare multiple burials: burial 41, which was dated through archaeological material to the period 530–640 CE.

(…) The biological analysis of the human remains recovered in the second burial (“burial 41”) enabled the demonstration of the combined presence of a woman of approximately 40 years old (A) and three immature individuals, including a 4–5-year-old child (B), a 14–16-year-old teenager (C) and a 2,5–3-month-old infant (D) (Lefebvre and Lafosse, 2016) (Fig. 1). Since rare multiple burials described for the Merovingian period in Northeast France mainly contained two or rarely three deceased, the discovery of a burial grouping four individuals reinforced its exceptional nature. (…) Intriguingly, great care was observed in the treatment of the dead, as illustrated through a special arrangement of the deceased in the grave (Fig. 1). Indeed, the woman A occupied a central position in the grave, with her left arm covering part of the body of child D, her right arm covering the torso of child B and her right hand covering the legs of children B and C. Several arguments, such as the close contact or the imbrication of the bones of individuals A, B and C, have attested to the simultaneity of their deposits in the burial (Lefebvre and Lafosse, 2016).

mitochondrial-distribution-merovingian
Geographic distribution of the extant European individuals sharing mitochondrial haplotypes with the Hérange human remains.

Interestingly, studies have demonstrated an important chronological homogeneity for the rare multiple burials discovered for the Merovingian period in the Lorraine region (Lefebvre and Lafosse, 2016). The collected data support the existence of an epiphenomenon arisen around the middle of the Merovingian period and that may have linked the multiple burials to (i) a funerary “fashion trend” for a special group of the community, (ii) an increase in cases of violence or (iii) an epidemic crisis linked to infectious disease. In other Lorraine sites, none of the available indices permitted the specification of the cause of death for the individuals recovered in these specific burials. The deceased could well have died of natural causes, violent acts or infectious diseases that had left no visible evidence on the skeletal.

merovingian-y-chromosome
Nuclear data (Y chromosome SNPs and nuclear STRs) typed on the four Hérange human remains (STRs alleles shown in grey were not fully replicated).

The aDNA analyses conducted on the four individuals discovered in the exceptional multiple burial 41 from Hérange (Lorraine) have demonstrated strong biological links between three individuals. Notably, we could propose that the woman A was the mother of the two immatures B and D deposited just besides her whereas she was not genetically closely related to the teenager C deposited along her legs. Consequently, we propose that the special arrangement of the deceased in the grave clearly reflected the degree of biological links between the deposited individuals. In Hérange, the bereaved were well aware of kinship among the deceased, wanted to express this close linkage through their relative location within the burial, and intentionally arranged body positions consequently. In conclusion, the collected archaeological, archaeo-anthropological and genetic data suggest that the special setup of the multiple burial 41 in the Hérange necropolis and the great care in the treatment of the dead, could be explained by the contemporaneous death of the four related individuals. Data gathered for other archaeological sites from the region or in Germany suggested an epidemic crisis (plague epidemic?) during the middle of the Merovingian period that may explain the contemporaneous death of related individuals living in close contact and easily sharing pathogens.

mitogenomes-merovingian

Reported mtDNA haplogroups include U* for samples A, B, and D, and H for sample C.

Related:

About Scepters, Horses, and War: on Khvalynsk migrants in the Caucasus and the Danube

steppe-horse-sceptre-khvalynsk

dergachev-scepters-khavlynsk-horsesAbout two months ago I stumbled upon a gem in archaeological studies related to Proto-Indo-Europeans, the book О скипетрах, о лошадях, о войне: этюды в защиту миграционной концепции М.Гимбутас (On sceptres, on horses, on war: Studies in defence of M. Gimbutas’ migration concepts), 2007, by V. A. Dergachev, from the Institute of Cultural Heritage of the Moldavian Republic.

Dergachev’s work dedicates 488 pages to a very specific Final Neolithic-Eneolithic period in the Pontic-Caspian steppe, and the most relevant parts of the book concern the nature and expansion of horses and horse domestication, horse-head scepters, and other horse-related symbology – arguably the most relevant cultural signs associated with Proto-Indo-European speakers in this period.

I haven’t had enough time to read the whole book, but I have read with interest certain important chapters.

About Scepters

Typological classification

The genetic and chronological relationship of horse-head pommel-scepters is classified with incredible detail, to the extent that one could divide subregions among those cultures using them.

khvalynsk-horse-head-scepters
Scheme of regional distribution – chronological – typological development of the carved horse-head stone scepters.

Simplified conclusions of this section include (emphasis mine):

  1. The [horse-head pommel-]scepters arose originally in the depth of the Khvalynsk culture. Following the now well-known finds, they are definitely related to those of the Middle Volga group.
  2. horse-head-pommel-scepters-distribution
    General scheme of genetic and chronological development of carved scepters by visual assessment of morphological details.
  3. In their next modifications, these scepters continued to evolve and develop into the area of the Khvalynsk culture in its latest stages, and possibly later.
  4. Simultaneously, with the same modifications, these scepters “are introduced” into common usage in the Novodanilovka culture, which in its spread by one wing was in contact and interspersed immediately with the area of Khvalynsk remains; and on the other hand, far in the south – in the Pre-Kuban and Ciscaucasian regions – within the range of the Domaikopska culture; and in the west – in the Carpathian – Post-Kuban – with the areas of early agricultural cultures Cucuteni A – Trypillia B1, Gumelnița-Karanovo VI.
  5. The simultaneous presence in the areas of the Ciscaucasian, Carpatho-Danubian, and especially Novodinilovka cultures, whose carriers continue the Khvalynian traditions of making stone scepters, and the scepters themselves (in their non-functional implication in the local cultural environment), all definitely allow us to view these findings as imported Novodanilovka objects.
distribution-horse-scepters
Schematic depiction of the spread of horse-head scepters in the Middle Eneolithic. See a full version with notes here.

Cultural relevance of scepters

The text goes on to make an international comparison of scepters and their relevance as a cultural phenomenon, with its strong symbolic functions as divine object, its use in times of peace, in times of war, and in a system of ritual power.

horse-scepters-steppe
Restoration of V. A. Dergachev: a) model for restoration – Paleolithic and Neolithic wands; b) the expected appearance of the Eneolithic scepter on the handle with a coupling (according to Dergachev 2007).
Especially interesting is the section dedicated to Agamemnon’s scepter in the Iliad, one of the oldest Indo-European epics. Here is an excerpt from Illiad II.100-110 (see here the Greek version) with the scepter’s human and divine genealogy:

Then among them lord Agamemnon uprose, bearing in his hands the sceptre which Hephaestus had wrought with toil. Hephaestus gave it to king Zeus, son of Cronos, and Zeus gave it to the messenger Argeïphontes; and Hermes, the lord, gave it to Pelops, driver of horses, and Pelops in turn gave it to Atreus, shepherd of the host; and Atreus at his death left it to Thyestes, rich in flocks, and Thyestes again left it to Agamemnon to bear, that so he might be lord of many isles and of all Argos.

About the horse

His studies on horse remains show an interesting, detailed quantitative and statistical approach to the importance and (cultural and chronological) origin of horses (and likely horse domestication) in each culture.

Although the part on horse remains is probably a bit outdated today, after many recent studies of Eneolithic steppe sites (see here one example), it still shows the relative distribution of horse bone remains among different steppe cultures, which is probably similar to what could be reported today:

distribution-horses-steppe-eneolithic
Territorial distribution of horse remains in the Middle Eneolithic period. Absolute and relative numbers.

Even more interesting is the relationship of the distribution of horse remains with archaeological complexes and horse-related symbols. Some excerpts from the conclusions of this section:

  1. Accounting and analysis of archeo-zoological and archaeological data proper for a horse for a vast area from the Tisza and the Middle Danube to the Caucasus and the Urals (which includes the main cultures of the western agricultural, Caucasian, and Eastern European cultural zones) clearly points to the eastern cultural zone as a zone of the originally the most important social significance of a horse as the only possible zone of the earliest domestication, horseback riding and all-round use of a horse. In relation to the eastern, the western land – the ancient Carpatho-Danubian or the Caucasian cultural zones – are secondary and subordinate to the first on the phenomenon under consideration.
  2. horse-symbols
    Horse-shaped hanger-amulets made of bone.
  3. The first quantitative leap in the manifestation of the remnants of a horse, marking itself and the first qualitative changes in the social status of this animal, is due mainly to the Middle Volga culture of the developed Neolithic of the Middle Volga region (in part, the Southwest Urals), which, accordingly, determine the cultural context, time and geographic region – or, the initial, single and main epicenter of the process of taming and domestication of a horse.
  4. On the one hand, the subsequent substantial increase in the number of horse remnants, and, on the other, the wide inclusion of the horse in cults, rituals, funerary rituals (horse pendants, ornamented metacarpus, horse bones, sacrificial altars) in the Samara culture of the Early Eneolithic of the same region definitely indicates the continuing increase in the social significance of this species of animal, which was most likely expressed in the final design of a specialized horse breeding culture and, accordingly, in a wide range of applications using a horse for riding. At the same time, we can observe the beginning of the transfer of the already domesticated horse from the original historical and geographic epicenter to other cultures of the eastern cultural zone and, in part, the cultures closest to the periphery of this zone, into the western agricultural zone (Bolgrad-Aldeni P, Pre-CuCuteni-Trypillya A) .
  5. expansion-horse-steppe
    Schematic depiction of cultures and regional-chronological distribution of percentage of horse remains. (Depicted are arrows from Middle Volga and Samara culture to the rest)
  6. Middle Eneolithic – early stages. One of the leading places in the remnants of the horse is in the Middle Volga region, the Khvalynsk culture. Genetically related to the Samara, the Khvalynsk I culture preserves the traditions of the ritual, cultural meaning, the treatment of the image of a horse in funerals (altars, horse bones, funerary rituals). But, At the same time, it is in this precise culture that the image of the horse, included in the social symbolism (horse-head pommel-scepter), for the first time it acquires a special, maximum social significance. That is why the appearance and subsequent widespread distribution of the social symbols in Novodanilovka-type objects can definitely be considered as another qualitative leap in the social significance of a horse – its use for military purposes for close and distant expeditions. And such an interpretation is fully confirmed from the analysis of Novodanilovka-type objects, which is the subject of discussion.
  7. Judging by the osteological data and the typological evolution of the horse-head scepters, the Khvalynian culture and remains of the Novodanilovka type are already associated with the relatively widespread and intensive findings of domesticated horses in various areas of the eastern cultural zone (semi-desert regions of the Lower Volga and the Caspian region – Khvalynsk culture, forest-steppe and steppe from the Volga to the Dnieper – Sredni Stog, Repin cultures), and the western – agricultural (Gumelnitsa, Cucuteni A-Tripolye Bl), and the Caucasus (Pre-Maykop) zones, where, however, the horse played a very modest role.
  8. samara-khvalynsk-horses
    Schematic depiction of cultures and regional-chronological distribution of zooarchaeological and ritual data on horses. (Shadowed are from top to bottom the Middle Volga, Samara, Khvalynsk, and Novodanilovka; in bold, other percentages of unrelated cultures: e.g. to the left of Khvalynsk and Novodanilovka, Sredni Stog with 29.65% overall horse bone remains, but 0% of horse symbolism)
  9. From the functional point of view, according to the sum of the data, there is no reason to doubt that in the eastern zone the horse is already present in the Late Neolithic period. Since its domestication and the emergence of a specialized horse breeding, it has been also widely used for meat, milk and dairy products (including the traditional hippace tradition of the later Scythians), and since the beginning of the early Eneolithic for transport and for riding purposes. Another thing is the horse as a means of war, a means of distant travel and expansion. The beginning of the use of a horse for these purposes, in the opinion of the author, is determined by the appearance of social symbolism in the form of horse-head scepters, and is most fully reflected in the memories of the Khvalynsk culture and, in particular, the Novodanilovka type. Concerning western or Caucasian cultural zones related to Khvalynsk, the horse is thought to have been linked to the eastern region, used mainly for riding, as a means of transport and for communication, which, however, does not exclude its use for meat.

These are the main conclusions-interpretations, suggesting the analysis and archaeological and other sources containing information about the horse. And as for our pommel-scepters, then, as can be seen from these sources, the main thing is that the culture of the Middle Volga region, according to all the data, definitely accumulates in itself the longest traditions associated with the gradual increase of social significance of the horse. And if so, this circumstance motivates the possibility or necessity of appearing in the environment of the bearers of this culture of unique signs-symbols that carry within themselves or reflect the image of this animal as an extremely significant social reality. The revealed and characterized quality, as a matter of fact, fill or open by themselves the hypothetical elements we have previously identified, the meanings of that particularity, folded in the social sign-symbol, in our case – the horse-head-shaped scepter.

horse-symbolism-rituals-steppe
Archaeological sites with objects (signs-symbols) related to horses. Horse-head scepters included in other maps are excluded from this one (notice the conspicuous absence of such objects in Sredni Stog and neighbouring North Pontic regions).

The relevance of Dergachev’s work

As you certainly know by now if you are a usual reader of this blog, there were two other seminal publications that same year correcting and expanding Gimbutas’ model:

Each one of these works taken independently (especially the books) may give a different version of Proto-Indo-European migrations; Anthony and Dergachev are heirs of Gimbutas’ simplistic kurgan-based model, and of other previous, now rejected ideas, and they reflect them whenever they don’t deal with first-hand investigation (and even sometimes when interpreting their own data). Taken together – and especially in combination with recent genetic studies – , though, they describe a clearer, solider model of how Proto-Indo-Europeans developed and expanded.

distribution-scepters-steppe
Distribution of horse-head scepters, according to Dergachev, Sorokin (1986).

Anthony’s publication overshadowed the importance of Dergachev’s work for the English-speaking world – and by extension for the rest of us. However, V. A. Dergachev’s updated study of his previous work on steppe cultures shows the right, thorough, and diligent way of describing the expansion of early Khvalynsk-Novodanilovka chieftains with the horse and horse symbolism into the Caucasus and the Lower Danube (like the seminal work of Harrison & Heyd 2007 described the expansion of Yamna settlers with East Bell Beakers, culturally opposed to Corded Ware and to the Proto-Beakers). On the other hand, Anthony’s broad-brush, superficial description of thousands of years of potential Indo-European-speaking peoples gave a migration picture that – although generally right (like radiocarbon-based Iberian origin of the Bell Beaker culture was right) – was bound to be wrong in some essential details, as we are seeing in archaeology and genetics.

NOTE. As I have said before, Anthony’s interpretations of Sredni Stog culture representing a sort of ‘peasants’ under the rule of Novodanilovka chiefs was based on old theories of Telegin, who changed his mind – as did the rest of the Russian school well before the publication of Dergachev’s book, considering both as distinct cultural phenomena. Anthony selected the old interpretation, not to follow a Gimbutas / Kristiansen model of Sredni Stog being Indo-European and expanding with GAC into Corded Ware (because, for him, Corded Ware peoples were originally non-Indo-European speakers): he seems to have done it to prove that Proto-Anatolian traveled indeed through the North Pontic area, i.e. to avoid the regional ‘gap’ in the maps, if you like. Then with the expansion of Repin over the area, Sredni Stog peoples would have been absorbed. With genetic investigation, as we know, and with this kind of detailed archaeological studies, the traditional preference for “large and early” IE territories – proper of the mid-20th century – are no longer necessary.

sredni-stog-suvorovo-novodanilovka-cernavoda
Anthony (2007): “Steppe and Danubian sites at the time of the Suvorovo-Novodanilovka intrusion, about 4200-3900 BC.”

Steppe Eneolithic

We already had in 2016 a Samara hunter-gatherer sample dated ca. 5600 BC, representative of EHG ancestry, of haplogroup R1b1a. We also had three early Khvalynsk samples from Samara Eneolithic dated ca. 4600 BC, with a drift towards (what we believe now is) a population from the Caucasus, showing haplogroups Q1a, R1a1(xM198), and R1b1a, the last one described in its paper as from a high-status burial, similar to high-status individuals buried under kurgans in later Yamna graves (of R1b-L23 lineages), and therefore likely a founder of an elite group of patrilineally-related families, while the R1a1 sample showed scarce decoration, and does not belong to the M417 lineage expanded later in Sredni Stog or Corded Ware.

In 2017 we knew of the Ukraine_Eneolithic sample I6561, from Alexandria, of a precise subclade (L657) of haplogroup R1a-Z93, dated ca. 4000 BC, and likely from the Sredni Stog (or maybe Kvitjana) culture. This sample alone makes it quite likely that the expansion of R1a-Z645 subclades happened earlier than expected, and that it was associated with movements along forest-steppe cultures, most likely along the Upper Dniester or Dnieper-Dniester corridor up to the Forest Zone.

We have now confirmation that Khvalynsk samples from the Yekaterinovka Cape settlement ca. 4250-4000 BC were reported by a genetic lab (to the archaeological team responsible) as being of R1b-L23 subclades, although the precise clades (reported as P312 and U106) are possibly not accurate.

NOTE. Curiously enough, and quite revealing for the close relationship of scepters to the ritual source of power for Khvalynsk chieftains (political and/or religious leaders), the scepter found in the elite burial 45 of the Ekaterinovka cape (a riverine settlement) shows a unique zoomorphic carving, possibly resembling a toothed fish or reptile, rather than the most common horse-related motifs of the time.

ekaterinovka-cape-scepter
Zoomorphic carved stone scepter of the Ekaterinovka Cape burial 45: photos (left) and schematic depiction (right).

With Wang et al. (2018), a real game-changer in the Khvalynsk – Sredni Stog (and also in the Yamna/Bell Beaker – Corded Ware) opposition, we also know that two Steppe Eneolithic samples from the Northern Caucasus Piedmont, dated ca. 4300-4100 BC, show haplogroup R1b1. Although its direct connection to the expansion of early Khvalynsk with horse-related symbolism is not clear from the archaeological information shared (none), this is what the paper has to say about them:

The two distinct clusters are already visible in the oldest individuals of our temporal transect, dated to the Eneolithic period (~6300-6100 yBP/4300-4100 calBCE). Three individuals from the sites of Progress 2 and Vonjuchka 1 in the North Caucasus piedmont steppe (‘Eneolithic steppe’), which harbor Eastern and Caucasian hunter-gatherer related ancestry (EHG and CHG, respectively), are genetically very similar to Eneolithic individuals from Khalynsk II and the Samara region19, 27. This extends the cline of dilution of EHG ancestry via CHG/Iranian-like ancestry to sites immediately north of the Caucasus foothills.

In contrast, the oldest individuals from the northern mountain flank itself, which are three first degree-related individuals from the Unakozovskaya cave associated with the Darkveti-Meshoko Eneolithic culture (analysis label ‘Eneolithic Caucasus’) show mixed ancestry mostly derived from sources related to the Anatolian Neolithic (orange) and CHG/Iran Neolithic (green) in the ADMIXTURE plot (Fig. 2C). While similar ancestry profiles have been reported for Anatolian and Armenian Chalcolithic and Bronze Age individuals20, 23, this result suggests the presence of the mixed Anatolian/Iranian/CHG related ancestry north of the Great Caucasus Range as early as ~6500 years ago.

On the specific burials, we have e.g. the recent open access paper New cases of trepanations from the 5th to 3rd millennia BC in Southern Russia in the context of previous research: Possible evidence for a ritually motivated tradition of cranial surgery?, by Gresky et al. J Am Phys Anthropol (2016):

During the late 5th millennium BC, cultural groups of the Eneolithic occupied the northern circumpontic area and the areas between the North Caucasus and the Lower Volga. For the first time, individual inhumations were placed below low burial mounds (Rassamakin, 2011). During the 4th millennium BC, the area split into two cultural spheres. In the northern steppe area communities continued with the burial practice of crouched inhumations below low mounds, with this culturally transforming into the early Pit Grave culture. In contrast, in the Caucasian foothill zone and the neighbouring steppe, the Majkop-Novosvobodnaya culture emerged (Kohl and Trifonov, 2014). Similarly, during the 3rd millennium BC, two cultural spheres influenced the area: The North Caucasian Culture dominated the Caucasian foothills for the next five centuries, while in the steppe area between the Lower Don and the Caucasus, regional groups of the Catacomb Culture existed side-by-side.

Burials of the Eneolithic epoch (late 5th millennium BC)

The oldest group of individuals with trepanations are found in the North Caucasian variant of the late circumpontic Eneolithic and date to the last third of the 5th millennium BC (Korenevsky, 2012). Burials of this epoch are inhumations in shallow pits, chiefly without burial goods, but covered with large quantities of red ochre. Of special interest is a collective burial of seven individuals from VP 1/12, who were interred together in a secondary burial ritual. The sites of Tuzluki, Mukhin, Voinuchka, Progress, and Sengileevskii all belong to this period.

PCA-caucasus-khvalynsk-sredni-stog
Image modified from Wang et al. (2018). Samples projected in PCA of 84 modern-day West Eurasian populations (open symbols). Previously known clusters have been marked and referenced. An EHG and a Caucasus ‘clouds’ have been drawn, leaving Pontic-Caspian steppe and derived groups between them.See the original file here.

Without the datasets to test different models, you can only imagine what is happening with the processed, secondary data we have. The position of Eneolithic Steppe cluster in the PCA (probably Khvalynsk-related peoples already influenced by the absorbed, previous Caucasus population), as well as other potential Caucasus groups intermediate between Steppe Maykop and Caucasus Maykop (as suggested by other ancient and modern Caucasus samples), may indicate that Yamna is between Khvalynsk and such intermediate Caucasus populations (as the source of the additional CHG-related ancestry) and – as the paper itself states – that it also received additional EEF contribution, probably from the western cultures absorbed during these Khvalynsk-Novodanilovka migrations (or later during Khvalynsk/Repin migrations).

Also interpreted in light of these early Khvalynsk-Novodanilovka migrations of horse riding chieftains (and their close contacts with the Caucasus), you can clearly see where the similar CHG-like contribution to Ukraine Eneolithic and other North Pontic forest-steppe cultures (which later contributed to Proto-Corded Ware peoples) must have come from. The simplistically reported proportions of EHG:CHG:EEF ancestry might be similar in many of these groups, but the precise origin and evolution of such ancestral components is certainly not the same: statistical methods will eventually show this, when (and if) we have many more samples, but for the moment Y-DNA is the most obvious indicator of such differences.

There was no steppe people speaking a steppe language AKA immutable Proto-Indo-European: the glottochronological models spanning thousands of years are not valid for the steppe, just as they are not valid for an Anatolian homeland, nor for a Caucasus homeland. The actual cultural-historical early Sredni Stog – Khvalynsk community, formed earlier than ca. 5000 BC, is a thousand years older than the expansion of Khvalynsk with the horse, and some two thousand years older than the expansion of Khvalynsk-Repin/Early Yamna migrants (see here for the latest genetic research).

What lies between the formation of that early Eneolithic cultural-historical community, and what we see in archaeology and genetics in Middle and Late Eneolithic steppe cultures, is the radical differentiation of western (Ukraine Eneolithic, mainly forest-steppe) and eastern (Samara and Khvalynsk/Repin, mainly steppe) cultures and peoples, i.e. precisely the period of differentiation of an eastern, Proto-Indo-Hittite-speaking early Khvalynsk community (that expanded with the horse and horse-related symbols) from a western, probably Early Proto-Uralic speaking community of the North Pontic forest-steppe cultural area.

NOTE. I am not against a Neolithic ‘steppe’ language. But this steppe language was spoken before and/or during the first Neolithisation wave, and should be associated with Indo-Uralic. If there was no Indo-Uralic language, then some communities would have developed Early Proto-Indo-European and Early Proto-Uralic side by side, in close contact to allow for dozens of loanwords or wanderwords to be dated to this period (where, simplistically, PIH *H corresponds to EPU *k, with some exceptions).

steppe-forest-change
Map of a) steppe – forest-steppe border during the Eneolithic in the Pontic-Caspian region and b) the border today, showing a more limited steppe zone in the North Pontic area (reason for the specific ways of expansion of horse-related cultures and horse-related nomadic pastoralism during the Eneolithic).

The convergence that we see in PCA and Admixture of Yamna and the earliest Baltic LN / Corded Ware ‘outlier’ samples (if not directly related exogamy of some Baltic LN/CWC groups with Yamna migrants, e.g. those along the Prut), must be traced back to the period of genetic drift that began precisely with these Khvalynsk-Novodanilovka expansions, also closely associated with populations of the Caucasus, thus bringing North Pontic forest-steppe cultures (probably behind Proto-Corded Ware peoples) nearer to Khvalynsk, and both by extension to Yamna.

We have seen this problem arise in Bell Beaker samples expanding all over Europe, turning from a fully Yamnaya-like population to something else entirely in different regions, from more EEF-like to more CWC-like, sharing one common trait: Y-DNA. We are seeing the same happen with Balkan groups and Mycenaeans, with Old Hittites, and with steppe MLBA from Andronovo peoples expanding over Central and South Asia, and we know that patrilineal clans and thus Y-chromosome bottlenecks were common after Neolithisation, especially with nomadic pastoralist steppe clans (and probably also with many previous population expansions).

Steppe Eneolithic peoples were thus no different to other previous and posterior expanding groups, and ancestry is going to be similar for people living in neighbouring regions, so Y-DNA will remain the essential tool to distinguish different peoples (see here a summary of Proto-Indo-Europeans expanding R1b-L23).

We are nevertheless still seeing “R1b zombies” (a quite appropriate name I read on Anthrogenica) still arguing for a Western European origin of R1b-L23 based on EEF-like ancestry and few steppe-related contribution found in Iberian Bell Beakers (read what David Reich has to say on this question); and “OIT zombies” still arguing for IVC representing Proto-Indo-European, based on Iran_N ancestry and the minimal steppe ancestry-related impact on certain ancient Asian cultures, now partly helped by “Caucasus homeland zombies” with the new PIE=CHG model; apart from many other pet theory zombies rising occasionally from their graves here and there. Let’s hope that this virus of the undead theories does not spread too strongly to the R1a-Indo-European association, when the official data on Khvalynsk, West Yamna, and Yamna Hungary come out and show that they were dominated by R1b-L23 lineages.

Because we need to explore in detail the continuation of Khvalynsk-related (potential Proto-Anatolian) cultures in the Lower Danube and the Balkans, e.g. from Cernavoda I to Cernavoda III, then maybe to Ezero, and then to Troy; as well as the specific areas of Late Indo-European expansions associated with Early Yamna settlers turning into Bell Beakers, Balkan EBA, and Steppe MLBA-associated cultures. There is a lot of work to do on proper definition of Bronze Age cultures and their potential dialects, as well as convergence and divergence trends, and not only of Indo-European, but also of Uralic-speaking communities derived from Corded Ware cultures.

If we let the narratives of the 2000s in Genetics (in combination with the 1960s in Archaeology) dominate the conversation, then a lot of time will be absurdly lost until reality imposes itself. And it will.

EDIT (2 JUL 2018): Some sentences corrected, and some information added to the original post.

Related

Reconstruction of Y-DNA phylogeny helps also reconstruct Tibeto-Burman expansion

tibeto-burman-han-chinese-population

New paper (behind paywall) Reconstruction of Y-chromosome phylogeny reveals two neolithic expansions of Tibeto-Burman populations by Wang et al. Mol Genet Genomics (2018).

Interesting excerpts:

Archeological studies suggest that a subgroup of ancient populations of the Miaodigou culture (~ 6300–5500 BP) moved westward to the upper stream region of the Yellow River and created the Majiayao culture (~ 5400–4900 BP) (Liu et al. 2010), which was proposed to be the remains of direct ancestors of Tibeto-Burman populations (Sagart 2008). On the other hand, Han populations, the other major descendant group of the Yang-Shao culture (~ 7000–5500 BP), are composed of many other sub-lineages of Oα-F5 and extremely low frequencies of D-M174 (Additional files 1: Figure S1; Additional files 2: Table S1). Therefore, we propose that Oα-F5 may be one of the dominant paternal lineages in ancient populations of Yang-Shao culture and its successors.

In this study, we demonstrated that both sub-lineages of D-M174 and Oα-F5 are founding paternal lineages of modern Tibeto-Burman populations. The genetic patterns suggested that the ancestor group of modern Tibeto-Burman populations may be an admixture of two distinct ancient populations. One of them may be hunter–gatherer populations who survived on the plateau since the Paleolithic Age, represented by varied sub-lineages of sub-lineages of D-M174. The other one was comprised of farmers who migrated from the middle Yellow River basin, represented by sub-lineages of Oα-F5. In general, the genetic evidence in this study supports the conclusion that the appearance of the ancestor group of Tibeto-Burman populations was triggered by the Neolithic expansion from the upper-middle Yellow River basin and admixture with local populations on the Tibetan Plateau (Su et al. 2000).

tibeto-burman-phylogenetic-tree
Simplified phylogenetic tree showing sample locations. The size of the circle for each sampling location corresponds to the number of samples

Two neolithic expansion origins of Tibeto‑Burman populations

We also observed significant differences in the paternal gene pool of different subgroups of Tibeto-Burman populations. Haplogroup D-M174 contributed ~ 54% percent in a sampling of 2354 Tibetan males throughout the Tibetan Plateau (Qi et al. 2013). Previous studies have also found high frequencies of D-M174 in other populations on the Tibetan Plateau (Shi et al. 2008), including Sherpa (Lu et al. 2016) and Qiang (Wang et al. 2014). In contrast, haplogroup D-M174 is rare or absent from Tibeto-Burman populations from Northeast India and Burma (Shi et al. 2008). In populations of the Ngwi-Burmese language subgroup, the average frequencies of haplogroup D-M174 are ~ 5% (Dong et al. 2004; Peng et al. 2014). Furthermore, we found that lineage Oα1c1b-CTS5308 is mainly found in Tibeto-Burman populations from the Tibetan Plateau. In contrast, lineage Oα1c1a-Z25929 was found in Tibeto-Burman populations from Northeast India, Burma, and the Yunan and Hunan provinces of China (Additional files 1: Figure S1; Additional files 2: Table S1). In general, enrichment of lineage Oα1c1b- CTS5308 and high frequencies of D-M174 can be found in most Tibeto-Burman populations on the Tibetan Plateau and adjacent regions, whereas Tibeto-Burman populations from other regions tend to have lineage Oα1c1a-Z25929 and a little to no percentage of D-M174.

The inconsistent pattern we observed in the paternal gene pool of modern Tibeto-Burman populations suggested that there may be two distinct ancestor groups (Fig. 3). The proposed migration routes shown in Fig. 3 are somewhat different from those proposed by Su et al. (2000). According to our age estimation, most of the D1a2a-P47 samples belong to sub-lineage PH116, a young lineage that emerged ~ 2500 years ago (95% CI 1915–3188 years). On the other hand, continuous differentiation can be observed on a phylogenetic tree of lineages D1a1a1a1-PH4979 and D1a1a1a2-Z31591 since 6000 years ago. Therefore, we proposed that a group of ancient populations may have moved to the upper basin of the Yellow River and admixed intensively with local populations with high frequencies of haplogroup D-M174, including its sub-lineage D1a2a-P47 (Fig. 3). This ancestor group eventually gave birth to modern Tibeto-Burman populations on the Tibetan Plateau and adjacent regions. The other ancestor group moved toward the southwest and finally reached South East Asia (Burma and other locations) and the northeastern part of India (Fig. 3). This ancestor group may have had no or a minor admixture of D-M174 in their paternal gene pool.

tibeto-burman-migrations
Two proposed ancestor groups and migration routes for Tibeto-Burman populations

Long‑term admixture before expansion to a high‑altitude region

It is interesting to investigate the time gap between the appearance of Neolithic cultures in the northeastern part of the Tibetan Plateau and the final phase of human expansion across the Tibetan Plateau. The Majiayao culture (~ 5400–4900 BP) is the earliest Neolithic culture in the northeastern part of the Tibetan Plateau (Liu et al. 2010). However, previous archeological study has suggested that the final phase of diffusion into the high-altitude area of the Tibetan Plateau occurred at approximately 3.6 kya (Chen et al. 2015). Our genetic evidence in this study is consistent with this scenario based on archeological evidence. Based on Y-chromosome analysis in this study, many unique lineages of Tibeto-Burman populations emerged between 6000 years ago and 2500 years ago (Additional files 3: Table S2). The most recent common age of D1a2-PH116, a sub-lineage that spread throughout the Tibetan Plateau, is only 2500 years ago.

We propose that there may be two important factors for the observed age gap. First, living in a high-altitude environment may require some crucial physical characteristics that were lacking from Neolithic immigrants from the middle Yellow River Basin. Intense genetic admixture with local people who had survived on the Tibetan Plateau since the Paleolithic Age may have actually guaranteed the expansion of humans across the Tibetan Plateau. Therefore, a long period of admixture, lasting from 5.4 to 3.6 kya, may be necessary for the appearance of a population with beneficial genetic variants that was genetically adapted to the high-altitude environment. Second, technological innovations, such as the domestication of wheat and highland barley (Chen et al. 2015), establishment of yak pastoralism (Rhode et al. 2007), and introduction of other culture elements in the Bronze Age (Ma et al. 2016), are also important factors that facilitated permanent settlements with large population sizes in the high-altitude area of the Tibetan Plateau.

Related:

Close inbreeding and low genetic diversity in Inner Asian human populations despite geographical exogamy

turko-mongol-indo-iranian

Open access Close inbreeding and low genetic diversity in Inner Asian human populations despite geographical exogamy, by Marchi et al. Scientific Reports (2018) 8:9397.

Abstract (emphasis mine):

When closely related individuals mate, they produce inbred offspring, which often have lower fitness than outbred ones. Geographical exogamy, by favouring matings between distant individuals, is thought to be an inbreeding avoidance mechanism; however, no data has clearly tested this prediction. Here, we took advantage of the diversity of matrimonial systems in humans to explore the impact of geographical exogamy on genetic diversity and inbreeding. We collected ethno-demographic data for 1,344 individuals in 16 populations from two Inner Asian cultural groups with contrasting dispersal behaviours (Turko-Mongols and Indo-Iranians) and genotyped genome-wide single nucleotide polymorphisms in 503 individuals. We estimated the population exogamy rate and confirmed the expected dispersal differences: Turko-Mongols are geographically more exogamous than Indo-Iranians. Unexpectedly, across populations, exogamy patterns correlated neither with the proportion of inbred individuals nor with their genetic diversity. Even more surprisingly, among Turko-Mongols, descendants from exogamous couples were significantly more inbred than descendants from endogamous couples, except for large distances (>40 km). Overall, 37% of the descendants from exogamous couples were closely inbred. This suggests that in Inner Asia, geographical exogamy is neither efficient in increasing genetic diversity nor in avoiding inbreeding, which might be due to kinship endogamy despite the occurrence of dispersal.

Interesting excerpts:

Two cultural groups, which matrimonial systems are reported to differ, coexist in Inner Asia: Turko-Mongols are described as mainly exogamous while Indo-Iranians are thought to be mainly endogamous45. However, it is not always clear if exogamy refers to clan (ethnic) or village (geographical) exogamy. Here, we used a dataset of 16 populations representing 11 different ethnic groups from both cultural groups and we quantified geographical exogamy rates and distances in each population. Using an empirical threshold of 4 km, we confirmed that matrimonial behaviours differ as described in the literature, even though we found some exceptions: three Turko-Mongol populations (out of 14) have less than 50% exogamy, whereas one Indo-Iranian population (out of four) has more than 50% exogamy.(…).

geographic-distance-turko-mongols-indo-iranian
Geographical distances between the birth places of couples in Turko-Mongols and Indo-Iranians. The geographical distances are plotted in log scale (km). Their densities are represented by population (dashed lines) or for the Indo-Iranian and Turko-Mongol groups (solid lines). We represented the average distances within couples per population using a Kernel’s density estimate implemented in R with a smoothing bandwidth of 0.2. See Supplementary Table 1B for population codes.

An additional important result of our study is that geographical distances are not negatively correlated with inbreeding, as could have been expected under an isolation-by-distance model65. Interestingly, a recent study based on a large genealogical dataset, collected across Western Europe and North America, and including birth places information, similarly found an absence of correlation between relatedness and the distance between couples, for the cohorts born before 185066. Our analyses within present-day Turko-Mongols reveal more specifically that the structure of the relationship between geographical distance and mating choice inbreeding is not linear, but rather tends to be bell-shaped, and thus cannot be correctly assessed with a single correlation test. Indeed, descendants from parents born 4 to 40 km apart are more inbred than descendants from endogamous couples (≤4 km) or from long-range exogamous ones (>40 km). As a consequence, close inbreeding exists despite geographical exogamy, and about a third of descendants from exogamous couples are inbred.

These results, in addition to those obtained by [Kaplanis et al. 2018]66, highlight the importance of using geographic distances rather than exogamy rates to characterize the impact of exogamy on inbreeding, as already described when studying patrilocality67. Indeed, when we compare mating choice inbreeding patterns for descendants from exogamous and endogamous couples defined for thresholds of 4, 10, 20 and 30 km, we find no significant differences (for number and total length of class C-ROHs and F-Median coefficient: MWU test p-values > 0.1). We only detect significantly lower values in descendants from exogamous couples for larger distances above 40 and 50 km (p-values < 0.03).

genetic-diversity-turko-mongol-indo-iranian
Genetic diversity (A) and inbreeding patterns (B,C) within populations. Grey lines in (B) represent inbreeding values corresponding to second-cousins and first-cousins. The grey line in (C) represents the homozygosity population baseline expected under panmixia. The number of samples per population is indicated between parentheses. See Supplementary Table 1B for population codes.

Our results also challenge the intuition that exogamy necessarily increases the genetic diversity within a population and therefore reduces drift inbreeding. Indeed, we found that Turko-Mongol populations have a lower genetic diversity (as measured by the mean haplotypic heterozygosity) and more intermediate ROHs associated with drift inbreeding than those of Indo-Iranians despite higher exogamous rates. (…)

Overall, this research sheds light on mating choice preferences: we showed that two thirds of partners that have not dispersed did mate with unrelated individuals, and that drift and mating choice inbreeding is variable, even among close-by populations. We also provide new insights into the relationship between dispersal and inbreeding in humans, based on genetic data, and demonstrate that geographical exogamy is not necessarily negatively associated with mating choice inbreeding, but rather can have a more complex non-linear relationship. Contrary to the common situation in many animals, this finding suggests that Inner Asian human populations who practise exogamy at small geographical scales might be focused on alliance strategies that result in kinship endogamy. (…)

Related:

Native American genetic continuity and oldest mtDNA hg A2ah in the Andean region

Native American gene continuity to the modern admixed population from the Colombian Andes: Implication for biomedical, population and forensic studies by Criollo-Rayo et al., Forensic Sci Int Genet (2018), in press, corrected proof.

Abstract (emphasis mine):

Andean populations have variable degrees of Native American and European ancestry, representing an opportunity to study admixture dynamics in the populations from Latin America (also known as Hispanics). We characterized the genetic structure of two indigenous (Nasa and Pijao) and three admixed (Ibagué, Ortega and Planadas) groups from Tolima, in the Colombian Andes. DNA samples from 348 individuals were genotyped for six mitochondrial DNA (mtDNA), seven non-recombining Y-chromosome (NRY) region and 100 autosomal ancestry informative markers. Nasa and Pijao had a predominant Native American ancestry at the autosomal (92%), maternal (97%) and paternal (70%) level. The admixed groups had a predominant Native American mtDNA ancestry (90%), a substantial frequency of European NRY haplotypes (72%) and similar autosomal contributions from Europeans (51%) and Amerindians (45%). Pijao and nearby Ortega were indistinguishable at the mtDNA and autosomal level, suggesting a genetic continuity between them. Comparisons with multiple Native American populations throughout the Americas revealed that Pijao, had close similarities with Carib-speakers from distant parts of the continent, suggesting an ancient correlation between language and genes. In summary, our study aimed to understand Hispanic patterns of migration, settlement and admixture, supporting an extensive contribution of local Amerindian women to the gene pool of admixed groups and consistent with previous reports of European-male driven admixture in Colombia.

andean-y-dna-mtdna
Ancestral uniparental haplogroups and diversity in Tolima. Geography of sampling locations. The
top and middle sections show the frequency of Native American mtDNA haplogroups and NRY lineages for all
populations. Gene diversity is shown below their respective pie chart. The lower part depicts the geography of the
region where the sampling sites of Ortega and Pijao are closely located in Tolima’s Magdalena river valley and
Ibague, Planadas and Nasa located in the Andes cordilleras (additional geographic details are shown in SF1).

Highlights from the paper:

  • MtDNA suggest a pre/post Columbian genetic continuity in the Colombian Andes.
  • Y-chromosome diversity follows a clinal gradient in the studied region.
  • Sex-biased/male-driven admixture process, involving Pijao women with European men.
  • Admixed closer to Indigenous resguardos have a higher Native American ancestry.

Also interesting is the recent paper Mitochondrial lineage A2ah found in a pre‐Hispanic individual from the Andean region, by Russo et al., in American Journal of Human Biology (2018), with an interesting sample from the Regional Developments II period (540 ± 60 BP).

phylogeny-a2ah-mtdna
Phylogeny of the A2ah mitochondrial lineage based on HVR I sequences. Both MaximumParsimony andMaximumLikelihood reconstructions led to the same typology. The tree was rooted with the RSRS. Sample ID: Cueva: Pukara de La Cueva, STACRUZ: Santa Cruz, BNI: Beni, BR: South-eastern Brazil, TobaChA: TobaGranChaco

Related:

Domesticated horse population structure, selection, and mtDNA geographic patterns

przewalski-hutai

Open access Detecting the Population Structure and Scanning for Signatures of Selection in Horses (Equus caballus) From Whole-Genome Sequencing Data, by Zhang et al, Evolutionary Bioinformatics (2018) 14:1–9.

Abstract (emphasis mine):

Animal domestication gives rise to gradual changes at the genomic level through selection in populations. Selective sweeps have been traced in the genomes of many animal species, including humans, cattle, and dogs. However, little is known regarding positional candidate genes and genomic regions that exhibit signatures of selection in domestic horses. In addition, an understanding of the genetic processes underlying horse domestication, especially the origin of Chinese native populations, is still lacking. In our study, we generated whole genome sequences from 4 Chinese native horses and combined them with 48 publicly available full genome sequences, from which 15 341 213 high-quality unique single-nucleotide polymorphism variants were identified. Kazakh and Lichuan horses are 2 typical Asian native breeds that were formed in Kazakh or Northwest China and South China, respectively. We detected 1390 loss-of-function (LoF) variants in protein-coding genes, and gene ontology (GO) enrichment analysis revealed that some LoF-affected genes were overrepresented in GO terms related to the immune response. Bayesian clustering, distance analysis, and principal component analysis demonstrated that the population structure of these breeds largely reflected weak geographic patterns. Kazakh and Lichuan horses were assigned to the same lineage with other Asian native breeds, in agreement with previous studies on the genetic origin of Chinese domestic horses. We applied the composite likelihood ratio method to scan for genomic regions showing signals of recent selection in the horse genome. A total of 1052 genomic windows of 10 kB, corresponding to 933 distinct core regions, significantly exceeded neutral simulations. The GO enrichment analysis revealed that the genes under selective sweeps were overrepresented with GO terms, including “negative regulation of canonical Wnt signaling pathway,” “muscle contraction,” and “axon guidance.” Frequent exercise training in domestic horses may have resulted in changes in the expression of genes related to metabolism, muscle structure, and the nervous system.

horse-admixture
Bayesian clustering output for 5 K values from K = 2 to K = 8 in 45 domestic horses. Each individual is represented by a vertical line, which is partitioned into colored segments that represent the proportion of the inferred K clusters.

Interesting excerpts:

Admixture proportions were assessed without user-defined population information to infer the presence of distinct populations among the samples (Figure 2). At K = 3 or K = 4, Franches-Montagnes and Arabian forms one unique cluster; at K = 5, Jeju pony forms one unique cluster. For other breeds, comparatively strong population structure exists among breeds, and they can be assigned to 2 (or 3) alternate clusters from K = 3 to K = 5 including group A (Duelmener, Fjord, Icelandic, Kazakh, Lichuan, and Mongolian) and group B (Hanoverian, Morgan, Quarter, Sorraia, and Standardbred). For group A, geographically this was unexpected, where Nordic breeds (Norwegian Fjord, Icelandic, and Duelmener) clustered with Asian breeds including the Mongolian. Previous results of mitochondrial DNA have revealed links between the Mongolian horse and breeds in Iceland, Scandinavia, Central Europe, and the British Isles. The Mongol horses are believed to have been originally imported from Russia subsequently became the basis for the Norwegian Fjord horse.31 At K = 6, Sorraia forms one unique cluster. The Sorraia horse has no long history as a domestic breed but is considered to be of a nearly ancestral type in the southern part of the Iberian Peninsula.32 However, our result did not support Sorraia as an independent ancestral type based on result from K = 2 to K = 5, and the unique cluster in K = 6 may be explained by the small population size and recently inbreeding programs. Genetic admixture of Morgan reveals that these breeds are currently or traditionally continually crossed with other breeds from K = 2 to K = 8. The Morgan horse has been a largely closed breed for 200 years or more but there has been some unreported crossbreeding in recent times.33

horse-pca
Principal component analysis results of all 48 horses. The x-axis denotes the value of PC1, whereas the y-axis denotes the value of PC2. Each dot in the figure represents one individual.

Bayesian clustering and PCA demonstrated the relationships among the horse breeds with weak geographic patterns. The tight grouping within most native breeds and looser grouping of individuals in admixed breeds have been reported previously in modern horses using data from a 54K SNP chip.33,34 Cluster analysis reveals that Arabian or Franches-Montagnes forms one unique cluster with relatively low K value, which is consistent with former study using 50K SNP chip 33,34 Interestingly, Standardbred forms a unique cluster with relatively high K value in this study, different from previous study.33 To date, no footprints are available to describe how the earliest domestic horses spread into China in ancient times. Our study found that Kazakh and Lichuan were assigned to the same lineage as other native Asian breeds, in agreement with previous studies on the origin of Chinese domestic horses.4,5,35,36 The strong genetic relationship between Asian native breeds and European native breeds have made it more difficult to understand the population history of the horse across Eurasia. Low levels of population differentiation observed between breeds might be explained by historical admixture. Unlike the domestic pig in China,8  we suggest that in China, Northern/Southern distinct groups could not be used to genetically distinct native Chinese horse breeds. We consider that during domestication process of horse, gene flow continued among Chinese-domesticated horses.


Open access Some maternal lineages of domestic horses may have origins in East Asia revealed with further evidence of mitochondrial genomes and HVR-1 sequences, by Ma et al., PeerJ (2018).

Abstract:

Objectives
There are large populations of indigenous horse (Equus caballus) in China and some other parts of East Asia. However, their matrilineal genetic diversity and origin remained poorly understood. Using a combination of mitochondrial DNA (mtDNA) and hypervariable region (HVR-1) sequences, we aim to investigate the origin of matrilineal inheritance in these domestic horses.

Methods
To investigate patterns of matrilineal inheritance in domestic horses, we conducted a phylogenetic study using 31 de novo mtDNA genomes together with 317 others from the GenBank. In terms of the updated phylogeny, a total of 5,180 horse mitochondrial HVR-1 sequences were analyzed.

Results
Eighteen haplogroups (Aw-Rw) were uncovered from the analysis of the whole mitochondrial genomes. Most of which have a divergence time before the earliest domestication of wild horses (about 5,800 years ago) and during the Upper Paleolithic (35–10 KYA). The distribution of some haplogroups shows geographic patterns. The Lw haplogroup contained a significantly higher proportion of European horses than the horses from other regions, while haplogroups Jw, Rw, and some maternal lineages of Cw, have a higher frequency in the horses from East Asia. The 5,180 sequences of horse mitochondrial HVR-1 form nine major haplogroups (A-I). We revealed a corresponding relationship between the haplotypes of HVR-1 and those of whole mitochondrial DNA sequences. The data of the HVR-1 sequences also suggests that Jw, Rw, and some haplotypes of Cw may have originated in East Asia while Lw probably formed in Europe.

Conclusions
Our study supports the hypothesis of the multiple origins of the maternal lineage of domestic horses and some maternal lineages of domestic horses may have originated from East Asia.

horse-mtdna
Median joining network constructed based on the 247- bp HVR-1 sequences. Circles are proportional to the number of horses represented and a scale indicator (for node sizes) was provided. The length of lines represents the number of variants that separate nodes (some manual adjustment was made for visually good). In the circles, the colors of solid pie slices indicate studied horse populations: Orange, European horses; Blue, horses of West Asia; Light Green, horses from East Asia; Grey, ancient horses; Purper, Przewalskii horses.

Geographic distributions of horse mtDNA haplogroups

The analysis of geographic distribution of the mitochondrial genome haplogroups showed that horse populations in Europe or East Asia included all haplogroups defined from the mtDNA genome sequences. The lineage Fw comprised entirely of Przewalskii horses. The two haplogroups Iw and Lw displayed frequency peaks in Europe (14.08% and 37.32%, respectively) and a decline to the east (9.33% and 8.00% in the West Asia, and 6.45% and 12.90% in East Asia, respectively), especially for Lw, which contained the largest number of European horses (Table 2). However, an opposite distribution pattern was observed for haplogroups Aw, Hw, Jw, and Rw, which were harbored by more horses from East Asia than those from other regions. The proportions of horses from East Asia for the four haplogroups were 38%, 88%, 62%, and 54%, respectively.

horse-mtdna-tree
Schematic phylogeny of mtDNAs genome from modern horses. This tree includes 348 sequences
and was rooted at a donkey (E. asinus) mitochondrial genome (not displayed). The topology was inferred by a beast approach, whereas a time divergence scale (based on rate substitutions) is shown on the bottom (age estimates were indicated with thousand years (KY)). The percentages on each branch represent Bayesian posterior credibility and the alphabets on the right represent the names of haplogroups. Additional details concerning ages were given in Tables S3 and S6.

Related:

Improving environmental conditions favoured higher local population density, which favoured domestication

agricultural-origins

New paper (behind paywall) Hindcasting global population densities reveals forces enabling the origin of agriculture, by Kavanagh et al., Nature Human Behaviour (2018)

Abstract (emphasis mine):

The development and spread of agriculture changed fundamental characteristics of human societies1,2,3. However, the degree to which environmental and social conditions enabled the origins of agriculture remains contested4,5,6. We test three hypothesized links between the environment, population density and the origins of plant and animal domestication, a prerequisite for agriculture: (1) domestication arose as environmental conditions improved and population densities increased7 (surplus hypothesis); (2) populations needed domestication to overcome deteriorating environmental conditions (necessity hypothesis)8,9; (3) factors promoting domestication were distinct in each location10 (regional uniqueness hypothesis). We overcome previous data limitations with a statistical model, in which environmental, geographic and cultural variables capture 77% of the variation in population density among 220 foraging societies worldwide. We use this model to hindcast potential population densities across the globe from 21,000 to 4,000 years before present. Despite the timing of domestication varying by thousands of years, we show that improving environmental conditions favoured higher local population densities during periods when domestication arose in every known agricultural origin centre. Our results uncover a common, global factor that facilitated one of humanity’s most significant innovations and demonstrate that modelling ancestral demographic changes can illuminate major events deep in human history.

cultural-variables-population-densities
Path diagram for piecewise-SEM exploring the effects of environmental and cultural variables on population densities of foraging societies. Measured variables are represented by the large boxes and R2 GLMM values (see Methods) are provided for response variables. n = 220. Red arrows depict negative relationships among variables, black arrows positive relationships, and dashed grey arrows depict non-significant paths (P ≥ 0.05). Standardized coefficients are presented for all paths (small boxes) and arrow widths are scaled to reflect the magnitude of path coefficients.

Interesting excerpts:

(…) our results are consistent with the surplus hypothesis, which suggests that improving environmental conditions and the potential for increased population density may have facilitated the domestication of plants and animals in agricultural origin centres4,7 (Fig. 3). Several factors may explain the links between environmental conditions, potential population density and the origin of domestication. For one, rates of innovation may scale positively with the number of potential innovators13,14. In turn, the likelihood of domestication innovations may have increased in environments that could support increasingly higher densities of foraging people.

In addition, foraging societies may have become more sedentary to take advantage of locally abundant resources, some of which were later domesticated35. Our results indicate that residential mobility scales negatively with population density in foraging societies (Fig. 1). Therefore, increasingly sedentary lifestyles may have contributed further to increases in population density and the potential for innovation. Increases in the productivity of wild progenitors of important domesticates may have also facilitated growing population densities and the viability of cultivation for food production15,16.

population-density-foragers
Predictions of potential population density for foragers. a–c, Predicted population densities at 4,000 (a), 10,000 (b) and 21,000 (c) YBP. Blue hues depict potential population densities below the median population density of observed foraging societies, and red hues depict potential population densities above the median. The second red hue and above are greater than the mean population density of observed foraging societies. Note the increase in area, through time, with potential population densities greater than the mean of observed foraging societies (number of 0.5° × 0.5° cells: 21,000 YBP = 3,027; 4,000 YBP = 4,673). For example, a notable increase in the number of red cells in the Sudanic savannah and Ganges of East India (Northeast India) between panels c and a.

It is also possible that improving environmental conditions may have resulted in a situation where necessity drove the origins of domestication. For example, population densities may have increased in foraging societies that occupied productive, coastal areas, causing an outflow of groups into regions with less ideal conditions where the cultivation of plants and animals was required to secure adequate food resources6,17,18. Our results cannot support, or refute, the possible influence the outflow of people from hospitable locations to less ideal environments may have played. A detailed understanding of the movements of ancient populations is required for more rigorous testing of the role that forced habitation of marginal environments may have played in the origins of domestication at particular sites.

See also:

Ancient human parallel lineages within North America contributed to a coastal expansion

americas-dispersal

New paper (behind paywall), Ancient human parallel lineages within North America contributed to a coastal expansion, by Scheib et al. Science (2018) 360(6392):1024-1027.

Abstract:

Little is known regarding the first people to enter the Americas and their genetic legacy. Genomic analysis of the oldest human remains from the Americas showed a direct relationship between a Clovis-related ancestral population and all modern Central and South Americans as well as a deep split separating them from North Americans in Canada. We present 91 ancient human genomes from California and Southwestern Ontario and demonstrate the existence of two distinct ancestries in North America, which possibly split south of the ice sheets. A contribution from both of these ancestral populations is found in all modern Central and South Americans. The proportions of these two ancestries in ancient and modern populations are consistent with a coastal dispersal and multiple admixture events.

americas-ancestry
Visual model of ancestry components and distribution of proportions in the Americas. (A) A model with four admixture events that offers a
good fit to the data (Z = 0.888) (15). (B) Scale of ANC-B ancestry from 0% in Anzick-1 to 100% in the ASO and modern Algonquian-speaking populations.

Interesting excerpts:

We modeled the population history of the Americas using qpGraph (15, 21) and found that the ASO and Mexican (Pima) populations were consistently outgroups to sets of clades formed by Anzick-1, SAM(Surui), and ESNpopulations in analyses that did not involve admixture (fig. S4) (15, 21). Fit between the data and the tree could be significantly improvedwhenmodeling ancient Californian, modern Pima, and Surui populations through admixture of two basal ancestries that we call ANC-A and ANC-B.

The clear separation of ANC-A and ANC-B ancestries is further supported by the sharing of unambiguous, derived haplotype segments in modern Surui and Pima populations (27) with both the ASO (CK-13) and Anzick-1 individuals (fig. S5) (15). The results of this analysis are consistent with ancient substructure and a separation of at least a few thousand years between the ANC-A and ANC-B populations prior to merging (fig. S6) (15). The summary of evidence presented here allows us to reject models of a panmictic “first wave” population from which the ASO diverged after the peopling of South America or in which solely the ANC-A population contributed to modern southern branch populations. Because populations vary in ANC-A and ANC-B proportions but do not differ significantly in their affinity to non-American populations (table S7) (15), it is possible that ANC-A and ANC-B split within America as opposed to Beringia where there would have been ongoing gene flow with Siberia.

Related: