Past Human Migration Research Articles

Exploring the potential of dental calculus to shed light on past human migrations in Oceania

The Pacific islands and Island Southeast Asia have experienced multiple waves of human migrations, providing a case study for exploring the potential of ancient microbiomes to study human migration. We perform a metagenomic study of archaeological dental calculus from 102 individuals, originating from 10 Pacific islands and 1 island in Island Southeast Asia spanning ~3000 years. Oral microbiome DNA preservation in calculus is far higher than that of human DNA in archaeological bone, and comparable to that of calculus from temperate regions. Oral microbial community composition is minimally driven by time period and geography in Pacific and Island Southeast Asia calculus, but is found to be distinctive compared to calculus from Europe, Africa, and Asia. Phylogenies of individual bacterial species in Pacific and Island Southeast Asia calculus reflect geography. Archaeological dental calculus shows good preservation in tropical regions and the potential to yield information about past human migrations, complementing studies of the human genome.

Mitochondrial DNA control-region and coding-region data highlight geographically structured diversity and post-domestication population dynamics in worldwide donkeys.

Donkeys (Equus asinus) have been used extensively in agriculture and transportations since their domestication, ca. 5000-7000 years ago, but the increased mechanization of the last century has largely spoiled their role as burden animals, particularly in developed countries. Consequently, donkey breeds and population sizes have been declining for decades, and the diversity contributed by autochthonous gene pools has been eroded. Here, we examined coding-region data extracted from 164 complete mitogenomes and 1392 donkey mitochondrial DNA (mtDNA) control-region sequences to (i) assess worldwide diversity, (ii) evaluate geographical patterns of variation, and (iii) provide a new nomenclature of mtDNA haplogroups. The topology of the Maximum Parsimony tree confirmed the two previously identified major clades, i.e. Clades 1 and 2, but also highlighted the occurrence of a deep-diverging lineage within Clade 2 that left a marginal trace in modern donkeys. Thanks to the identification of stable and highly diagnostic coding-region mutational motifs, the two lineages were renamed as haplogroup A and haplogroup B, respectively, to harmonize clade nomenclature with the standard currently adopted for other livestock species. Control-region diversity and population expansion metrics varied considerably between geographical areas but confirmed North-eastern Africa as the likely domestication center. The patterns of geographical distribution of variation analyzed through phylogenetic networks and AMOVA confirmed the co-occurrence of both haplogroups in all sampled populations, while differences at the regional level point to the joint effects of demography, past human migrations and trade following the spread of donkeys out of the domestication center. Despite the strong decline that donkey populations have undergone for decades in many areas of the world, the sizeable mtDNA variability we scored, and the possible identification of a new early radiating lineage further stress the need for an extensive and large-scale characterization of donkey nuclear genome diversity to identify hotspots of variation and aid the conservation of local breeds worldwide.

Investigating Past Livestock Mobility Using δ34S Stable Isotopes: Three Preliminary Case Studies From Prehistoric Croatia

The benefit of including sulfur (δ³⁴S) stable isotopes in studies of past human diet and migration is increasingly clear, but δ³⁴S analyses remain underutilized in addressing other patterns of mobility, animal management, and environmental change in the archaeological record. Here we evaluate the ability of δ³⁴S isotope values to act as proxies for prehistoric environments in three distinct regions of Croatia: northern Dalmatia, Lika, and central Croatia. We then assess if δ³⁴S isotope values can highlight differences in herding and management practices of livestock in these areas, specifically those that encourage the movement of herds into various parts of the landscape (e.g., transhumance vs. localized grazing). Analysis of faunal stable isotope values from these geographically diverse sites constitute the first step in building an environmental database for Croatia and addressing questions of how δ³⁴S can be applied to questions about animal husbandry in the archaeological record.

Origin and Demographic History of Philippine Pigs Inferred from Mitochondrial DNA.

The Philippines is a mega-diverse country that lies at the crossroads of past human migrations in the Asia-Pacific region and is believed to have never been connected to the Asian continent, even during the major sea-level subsidence of the Quaternary. As a result, the history of pig dispersal in the Philippines remains controversial, due to limited molecular studies and absence of archaeological evidence of pig domestication. This study provides the first comprehensive analysis of 184 complete mitochondrial DNA D-loop region from Philippine pigs to elucidate their early dispersal history by performing a phylogenetic comparison with wild boars and domestic pigs worldwide. The results showed a demographic signal of the ancestry of Philippine pigs that had a close genetic relationship with those from the mainland Southeast Asia and Northeast Asia, suggesting gene flow that may have resulted from human migration and trade. Here we have suggested two possible dispersal routes. One parallels the Neolithic expansion in Island Southeast Asia and Oceania via Northeast Asia, the other from the mainland Southeast Asia, into Palawan and Sulu Archipelago as early as prehistoric times via the Sundaic Region. Despite geographic barriers to migration, numerous genetic lineages have persisted across the Philippine islands, even justifying the recognition of a Philippine Lanyu subclade. The prehistoric population history suggests a demographic expansion that coincided with the interglacial periods of the Pleistocene and may have spread from the southern regions into the eastern and central regions of the Philippines. The intriguing signal of discrepancy discovered between the ancestral pattern and distribution range of the numerous endemic Philippine wild pigs opens a challenging new approach to illuminate complexity among these animals. Our study has contributed significantly towards completing the sparse molecular studies on Philippine pigs, an essential for creating win-win conservation measures.

Late Pleistocene Climate and Dust Source From the Mobarakabad Loess–Paleosol Sequence, Northern Foothills of the Alborz Mountains, Northern Iran

Paleoclimatic investigation of loess-paleosol sequences from northern Iran is important for understanding past changes in a region highly sensitive to shifts in precipitation, and along potential routes of past human migration. Here, we present carbon and oxygen isotopic compositions of bulk carbonate (δ13Cbc and δ18Obc, respectively) coupled with particle size distributions of samples from the Mobarakabad section, northern Iran, to study past wind dynamics and hydroclimate. We also present new initial clay-sized Hf-Nd isotope results from key horizons in order to assess general dust sources. Variations of δ13Cbc and δ18Obc values of modern soils compared to paleosols allow reconstruction of late Pleistocene–Holocene climate change in the area. Our results show severe drought during a major eolian deposition phase (EDP) after 34 ka. The thickness and PSD of the C horizon of unit 5 suggest significant shifts in loess sources and depositional environments during this EDP after 34 ka. Indeed, based on our new clay-sized Hf-Nd data, we hypothesize that the loess unit 5 might originate from the young crustal source of the Alborz and Kopet Dagh mountains. In general, the PSD of C horizons in the section is bimodal in the silt fraction and the very small, very fine clay fraction, with a mode at c. 1 μm in the modern soil and paleosols possibly produced by weathering and pedogenic processes. There also appears to be a good correlation between δ13Cbc and δ18Obc values, differentiating phases of loess accumulation and paleosol formation and hence providing quantitative data for reconstructing paleoclimatic conditions in the study area.

Genomic Analysis of 18th-Century Kazakh Individuals and Their Oral Microbiome.

Simple SummaryPaleogenomic research has enhanced our understanding of past human populations and migrations. Moreover, ancient DNA can also provide information on the interactions between humans and their associated pathogens. Periodontitis, currently suffered by millions of people worldwide, is a gum infection that is caused by pathogenic oral bacteria, widely referred to as the “red complex”, which can lead to tooth loss and has been linked to an increased risk of oesophageal cancer. In this study we combine human population genetics with genomic analysis of the oral microbiome of 18th-century people from the Kazakh Khanate in Kazakhstan to gain insight into their health status and explore bacterial coadaptation to recent dietary changes.The Asian Central Steppe, consisting of current-day Kazakhstan and Russia, has acted as a highway for major migrations throughout history. Therefore, describing the genetic composition of past populations in Central Asia holds value to understanding human mobility in this pivotal region. In this study, we analyse paleogenomic data generated from five humans from Kuygenzhar, Kazakhstan. These individuals date to the early to mid-18th century, shortly after the Kazakh Khanate was founded, a union of nomadic tribes of Mongol Golden Horde and Turkic origins. Genomic analysis identifies that these individuals are admixed with varying proportions of East Asian ancestry, indicating a recent admixture event from East Asia. The high amounts of DNA from the anaerobic Gram-negative bacteria Tannerella forsythia, a periodontal pathogen, recovered from their teeth suggest they may have suffered from periodontitis disease. Genomic analysis of this bacterium identified recently evolved virulence and glycosylation genes including the presence of antibiotic resistance genes predating the antibiotic era. This study provides an integrated analysis of individuals with a diet mostly based on meat (mainly horse and lamb), milk, and dairy products and their oral microbiome.

Contact-tracing in cultural evolution: a Bayesian mixture model to detect geographic areas of language contact.

When speakers of different languages interact, they are likely to influence each other: contact leaves traces in the linguistic record, which in turn can reveal geographical areas of past human interaction and migration. However, other factors may contribute to similarities between languages. Inheritance from a shared ancestral language and universal preference for a linguistic property may both overshadow contact signals. How can we find geographical contact areas in language data, while accounting for the confounding effects of inheritance and universal preference? We present sBayes, an algorithm for Bayesian clustering in the presence of confounding effects. The algorithm learns which similarities are better explained by confounders, and which are due to contact effects. Contact areas are free to take any shape or size, but an explicit geographical prior ensures their spatial coherence. We test sBayes on simulated data and apply it in two case studies to reveal language contact in South America and the Balkans. Our results are supported by findings from previous studies. While we focus on detecting language contact, the method can also be used to uncover other traces of shared history in cultural evolution, and more generally, to reveal latent spatial clusters in the presence of confounders.

Human population history at the crossroads of East and Southeast Asia since 11,000 years ago

Past human genetic diversity and migration between southern China and Southeast Asia have not been well characterized, in part due to poor preservation of ancient DNA in hot and humid regions. We sequenced 31 ancient genomes from southern China (Guangxi and Fujian), including two ∼12,000- to 10,000-year-old individuals representing the oldest humans sequenced from southern China. We discovered a deeply diverged East Asian ancestry in the Guangxi region that persisted until at least 6,000 years ago. We found that ∼9,000- to 6,000-year-old Guangxi populations were a mixture of local ancestry, southern ancestry previously sampled in Fujian, and deep Asian ancestry related to Southeast Asian Hòabìnhian hunter-gatherers, showing broad admixture in the region predating the appearance of farming. Historical Guangxi populations dating to ∼1,500 to 500 years ago are closely related to Tai-Kadai and Hmong-Mien speakers. Our results show heavy interactions among three distinct ancestries at the crossroads of East and Southeast Asia.

Sr isotopic composition as a tool for unraveling human mobility in the Campania area

Recent strontium isotope (87Sr/86Sr) analyses of bones and teeth have provided useful archeological results for reconstructing past human migration and diet. We report 87Sr/86Sr ratios and DNA analyses of tooth enamel from individuals buried in some necropolises in Nola town, near Napoli (Campania, South Italy). These individuals lived in the period between the Avellino (1925 years BCE) and CE 472 Pollena Vesuvian eruptions and are dated on archeological basis to the time span between the sixth and second century BCE. Tooth enamel 87Sr/86Sr ratios (0.70788–0.70864) are higher than baseline values in the necropolises (0.70756–0.70792): this can be explained by assuming either that all the analyzed individuals are not local—an unlikely possibility—or that they ate both local and foreign food (within about 50 km), including 87Sr-rich seafood. An explanation for such a varied diet might be that the individuals from Nola were living near the Ancient Appia and Popilia ways and not far from the coastline. Whatever its origin, the 87Sr/86Sr ratios represent the isotopic signature of the local community living on the slopes of Mt. Somma-Vesuvius between the sixth and second centuries BCE. This knowledge will support future isotope studies on volcanic eruptions as possible causes of human migration.

Genome-wide genotyping elucidates the geographical diversification and dispersal of the polyploid and clonally propagated yam (Dioscorea alata).

Background and AimsInferring the diffusion history of many human-dispersed species is still not straightforward due to unresolved past human migrations. The centre of diversification and routes of migration of the autopolyploid and clonally propagated greater yam, Dioscorea alata, one of the oldest edible tubers, remain unclear. Here, we address yam demographic and dispersal history using a worldwide sample.MethodsWe characterized genome-wide patterns of genetic variation using genotyping by sequencing 643 greater yam accessions spanning four continents. First, we disentangled the polyploid and clonal components of yam diversity using allele frequency distribution and identity by descent approaches. We then addressed yam geographical origin and diffusion history with a model-based coalescent inferential approach.Key ResultsDiploid genotypes were more frequent than triploids and tetraploids worldwide. Genetic diversity was generally low and clonality appeared to be a main factor of diversification. The most likely evolutionary scenario supported an early divergence of mainland Southeast Asian and Pacific gene pools with continuous migration between them. The genetic make-up of triploids and tetraploids suggests that they have originated from these two regions before westward yam migration. The Indian Peninsula gene pool gave origin to the African gene pool, which was later introduced to the Caribbean region.ConclusionsOur results are congruent with the hypothesis of independent domestication origins of the two main Asian and Pacific gene pools. The low genetic diversity and high clonality observed suggest a strong domestication bottleneck followed by thousands of years of widespread vegetative propagation and polyploidization. Both processes reduced the extent of diversity available for breeding, and this is likely to threaten future adaptation.

Palaeomicrobiology: Application of Ancient DNA Sequencing to Better Understand Bacterial Genome Evolution and Adaptation

Next Generation Sequencing (NGS) has unlocked access to the wide range of non-cultivable microorganisms, including those present in the ancient past. The study of microorganisms from ancient sources (palaeomicrobiology) using DNA sequencing now provides a unique opportunity to examine ancient microbial genomic content, explore pathogenicity, and understand microbial evolution in greater detail than ever before. As a result, current studies have focused on reconstructing the evolutionary history of a number of human pathogens involved in ancient and historic pandemic events. These studies have opened the door for a variety of future palaeomicrobiology studies, which can focus on commensal microorganisms, species from non-human hosts, information from host-genomics, and the use of bacteria as proxies for additional information about past human health, behavior, migration, and culture. Here, we describe the origin and the historical and recent advances in the field of palaeomicrobiology, review some of the most notable ancient pathogenic microorganism studies, and provide perspectives on how NGS and whole genome information from ancient microorganisms contribute to our understanding of bacterial evolution on a broader scale. We conclude by exploring the application of newly developed tools in palaeomicrobiology and discussing how future studies can improve our current understanding of the co-evolution relationships between humans and non-pathogenic microbes.

Ancient genomes from northern China suggest links between subsistence changes and human migration

Northern China harbored the world’s earliest complex societies based on millet farming, in two major centers in the Yellow (YR) and West Liao (WLR) River basins. Until now, their genetic histories have remained largely unknown. Here we present 55 ancient genomes dating to 7500-1700 BP from the YR, WLR, and Amur River (AR) regions. Contrary to the genetic stability in the AR, the YR and WLR genetic profiles substantially changed over time. The YR populations show a monotonic increase over time in their genetic affinity with present-day southern Chinese and Southeast Asians. In the WLR, intensification of farming in the Late Neolithic is correlated with increased YR affinity while the inclusion of a pastoral economy in the Bronze Age was correlated with increased AR affinity. Our results suggest a link between changes in subsistence strategy and human migration, and fuel the debate about archaeolinguistic signatures of past human migration.

Childhood mobility revealed by strontium isotope analysis: a review of the multiple tooth sampling approach

Strontium isotope analysis of archeological skeletal materials is a highly effective and commonly employed analytical tool to investigate past human mobility and migration. Most such studies to date have focused on the analysis of a single tooth sample per individual to identify migration. Increasingly, however, studies have analyzed multiple teeth from the same individual permitting the detection of migrations occurring during childhood, more fine-grained temporal resolution of the age at which migration(s) occurred, and even the identification of multiple migration episodes. In this study, we review the application of such approaches to a wide range of archeological contexts worldwide. We compiled and analyzed published 87Sr/86Sr data for 1043 individuals from 122 sites to explore the potential variability of childhood mobility patterns cross-culturally. The results demonstrate a high degree of variability in childhood mobility that differs significantly between different regions and time periods. Potential interpretations involved in multiple tooth 87Sr/86Sr analysis are reviewed, including heterogeneity in variance of regional 87Sr/86Sr, as well as variability in human mobility patterns such as residential change of whole family, fosterage, herding activities, post-marital residence rules, or forced migrations. Various limitations and caveats concerning the multiple teeth sampling approach are also critically discussed.

Spatio-temporal patterns in the postglacial flooding of the Great Barrier Reef shelf, Australia

The shelf of the Great Barrier Reef (GBR) was progressively marine flooded from the last glaciation maximum (LGM) (ca 20 ka BP) until the last sea-level highstand (ca 6 ka BP), affecting the depositional evolution of the GBR margin and associated deposits. However, the physiographic variables related to this process have not been fully characterized, especially in relation to the sedimentary processes at the shelf margin. For this study, we used a bathymetric model of the entire shelf and a shelf margin sub-set, divided into 33 latitudinal zones. Postglacial marine flooding was simulated and flooded area (km2), flooding magnitude (km2 per sea-level increment), flooding rate (km2 ky−1) and coastline length (km) were estimated for each zone, from 130 m to 0 m below present sea level, representing the period from 20 ka to 6 ka BP. Our results show that the postglacial marine flooding did not occur uniformly and that some sub-regions (e.g. the southern-central GBR) had early and rapid flooding. Coastal complexity increased in the mid-postglacial, reaching maximum values at around 9 ka BP. This reflects a coastal landscape evolving from a linear, laterally connected coast to a complex coast dominated by estuaries and lagoons, partly returning to its initial linearity during highstand. Flooding trends and geological evidence make two depositional relationships apparent. Firstly, the timing and magnitude of the off-shelf sediment flux appears linked to the presence and orientation of a shelf-edge rim, and to the extension and morphology of the evolving drainage network. Secondly, the periods of shelf-edge reef development and demise seem to respond to the remobilisation, trapping or redirection of fine sediments. We propose a sedimentation model for the shelf margin and the slope driven by the interplay of sea-level rise and shelf physiography, and we highlight two fundamental processes: (1) the cross-shelf sediment transport related to coastline retreat under rising sea levels, and (2) the effectiveness of transient embayments in redirecting or trapping sediments. The quantifications provided in this study have implications in the estimation of Pleistocene carbonate budgets and the atmospheric carbon cycle, as well as for past human migrations.

Early medieval reliance on the land and the local: An integrated multi-isotope study (87Sr/86Sr, δ18O, δ13C, δ15N) of diet and migration in Co. Meath, Ireland

Three early medieval Irish communities within a 30-km radius in Co. Meath, Ireland, have been examined using multiple isotopes (87Sr/86Sr, δ18O, δ13C, δ15N) to elucidate human and domesticated animal subsistence and provenance. Existing 87Sr/86Sr data from geochemical mapping of contemporary soils, plants and streamwater were compared to human and animal tooth enamel 87Sr/86Sr to assess potential past human migration, in combination with δ18O from bone collagen. Oxygen isotope (δ18O) values of human bone collagen are notably invariable, 10.0 ± 0.6‰ (n = 36), for the three archaeological sites: Collierstown, Johnstown and Raystown. Fauna (sheep, pigs, cats and a dog) δ18Ocollagen from Raystown are distinctly grouped between and among certain species, the first instance to our knowledge of such a result. The aggregate faunal data demonstrate that δ18Ocollagen values of faunal remains should not be used to infer local δ18O ranges for humans.Nitrogen isotope (δ15N) values for both domesticated animal (9.8 ± 1.7‰) and adult human (12.0 ± 0.8‰) bone collagen are tightly constrained suggesting a similar source of protein in the diet of humans. A mean carbon isotope (δ13C) value of −21.0 ± 0.4‰ for adult humans indicates overwhelming terrestrial sources of foodstuffs. Strontium isotope ratios (87Sr/86Sr) from human dental enamel range from 0.7085-0.7110 (n = 25). Two individuals (R841 and R854), both from Raystown, are statistical outliers based on their 87Sr/86Sr and δ13C values and are likely migrants to the locality where they were buried. We note that one of these putative migrants met a particularly violent end.

Ancient human genomes-keys to understanding our past.

Ancient genomes from different times and continents are helping to understand past human migrations

Ancient Microbial DNA in Dental Calculus: A New method for Studying Rapid Human Migration Events

ABSTRACTAncient human migrations provide the critical genetic background to historical and contemporary human demographic patterns. However, our ability to infer past human migration events, especially those that occurred over rapid timescales, is often limited. A key example is the peopling of Polynesia, where the timing is relatively well defined, but the exact routes taken during the final stages and the source populations are not. Here, we discuss the technical limitations of current methods for inferring rapid human migration events, using the final stages of Polynesian migration as an example. We also introduce a promising new proxy method to infer human migrations—patterns of bacterial evolution within ancient dental calculus (calcified plaque). While we focus on Polynesia, this method should be applicable to other past migrations, enhancing our understanding of human prehistory and revealing the crucial events that shaped it.

Local genes for local bacteria: Evidence of allopatry in the genomes of transatlantic Campylobacter populations.

The genetic structure of bacterial populations can be related to geographical locations of isolation. In some species, there is a strong correlation between geographical distance and genetic distance, which can be caused by different evolutionary mechanisms. Patterns of ancient admixture in Helicobacter pylori can be reconstructed in concordance with past human migration, whereas in Mycobacterium tuberculosis it is the lack of recombination that causes allopatric clusters. In Campylobacter, analyses of genomic data and molecular typing have been successful in determining the reservoir host species, but not geographical origin. We investigated biogeographical variation in highly recombining genes to determine the extent of clustering between genomes from geographically distinct Campylobacter populations. Whole‐genome sequences from 294 Campylobacter isolates from North America and the UK were analysed. Isolates from within the same country shared more recently recombined DNA than isolates from different countries. Using 15 UK/American closely matched pairs of isolates that shared ancestors, we identify regions that have frequently and recently recombined to test their correlation with geographical origin. The seven genes that demonstrated the greatest clustering by geography were used in an attribution model to infer geographical origin which was tested using a further 383 UK clinical isolates to detect signatures of recent foreign travel. Patient records indicated that in 46 cases, travel abroad had occurred <2 weeks prior to sampling, and genomic analysis identified that 34 (74%) of these isolates were of a non‐UK origin. Identification of biogeographical markers in Campylobacter genomes will contribute to improved source attribution of clinical Campylobacter infection and inform intervention strategies to reduce campylobacteriosis.

Supernumerary heads to biceps brachii muscle and Asian population history

Supernumerary heads of biceps brachii are one of the most common anatomic variants in the muscular system and appear to develop under genetic control and vary in prevalence among populations. Variation in prevalence and morphology therefore has the potential to contribute to understanding of human population history. Until now, there has been no publication of the prevalence of the variant in Southeast Asian populations. The aim of this research is to document the prevalence and morphology of the variant in a sample of Thai cadavers and to consider the significance of the findings. The method used was dissection of arms of 162 donated cadavers at Khon Kaen University, Thailand. The sample showed high prevalence of third heads of biceps brachii in 35% of cadavers, compared with the prevalence of up to 25% reported in large samples worldwide. The sample also showed equal prevalence in males and females and one-third present bilaterally. This pattern is similar to that found in East Asia, and very different from the low prevalence found in South Asia. The morphology of the supernumerary heads does not appear to be different from elsewhere in the world based on the minimal comparable data available in the literature. The Southeast-East Asian pattern of prevalence is consistent with current theories of population history in the region and suggests anatomical variation of the postcranial soft tissues may ultimately contribute to understanding of past human migrations.

On the Use of Biomineral Oxygen Isotope Data to Identify Human Migrants in the Archaeological Record: Intra-Sample Variation, Statistical Methods and Geographical Considerations.

Oxygen isotope analysis of archaeological skeletal remains is an increasingly popular tool to study past human migrations. It is based on the assumption that human body chemistry preserves the δ18O of precipitation in such a way as to be a useful technique for identifying migrants and, potentially, their homelands. In this study, the first such global survey, we draw on published human tooth enamel and bone bioapatite data to explore the validity of using oxygen isotope analyses to identify migrants in the archaeological record. We use human δ18O results to show that there are large variations in human oxygen isotope values within a population sample. This may relate to physiological factors influencing the preservation of the primary isotope signal, or due to human activities (such as brewing, boiling, stewing, differential access to water sources and so on) causing variation in ingested water and food isotope values. We compare the number of outliers identified using various statistical methods. We determine that the most appropriate method for identifying migrants is dependent on the data but is likely to be the IQR or median absolute deviation from the median under most archaeological circumstances. Finally, through a spatial assessment of the dataset, we show that the degree of overlap in human isotope values from different locations across Europe is such that identifying individuals’ homelands on the basis of oxygen isotope analysis alone is not possible for the regions analysed to date. Oxygen isotope analysis is a valid method for identifying first-generation migrants from an archaeological site when used appropriately, however it is difficult to identify migrants using statistical methods for a sample size of less than c. 25 individuals. In the absence of local previous analyses, each sample should be treated as an individual dataset and statistical techniques can be used to identify migrants, but in most cases pinpointing a specific homeland should not be attempted.