Prehistoric Migrations Research Articles

Genetics of the pig tapeworm in madagascar reveal a history of human dispersal and colonization.

An intricate history of human dispersal and geographic colonization has strongly affected the distribution of human pathogens. The pig tapeworm Taenia solium occurs throughout the world as the causative agent of cysticercosis, one of the most serious neglected tropical diseases. Discrete genetic lineages of T. solium in Asia and Africa/Latin America are geographically disjunct; only in Madagascar are they sympatric. Linguistic, archaeological and genetic evidence has indicated that the people in Madagascar have mixed ancestry from Island Southeast Asia and East Africa. Hence, anthropogenic introduction of the tapeworm from Southeast Asia and Africa had been postulated. This study shows that the major mitochondrial haplotype of T. solium in Madagascar is closely related to those from the Indian Subcontinent. Parasitological evidence presented here, and human genetics previously reported, support the hypothesis of an Indian influence on Malagasy culture coinciding with periods of early human migration onto the island. We also found evidence of nuclear-mitochondrial discordance in single tapeworms, indicating unexpected cross-fertilization between the two lineages of T. solium. Analyses of genetic and geographic populations of T. solium in Madagascar will shed light on apparently rapid evolution of this organism driven by recent (<2,000 yr) human migrations, following tens of thousands of years of geographic isolation.

Pleistocene cave art from Sulawesi, Indonesia.

Archaeologists have long been puzzled by the appearance in Europe ∼40-35 thousand years (kyr) ago of a rich corpus of sophisticated artworks, including parietal art (that is, paintings, drawings and engravings on immobile rock surfaces) and portable art (for example, carved figurines), and the absence or scarcity of equivalent, well-dated evidence elsewhere, especially along early human migration routes in South Asia and the Far East, including Wallacea and Australia, where modern humans (Homo sapiens) were established by 50kyr ago. Here, using uranium-series dating of coralloid speleothems directly associated with 12 human hand stencils and two figurative animal depictions from seven cave sites in the Maros karsts of Sulawesi, we show that rock art traditions on this Indonesian island are at least compatible in age with the oldest European art. The earliest dated image from Maros, with a minimum age of 39.9kyr, is now the oldest known hand stencil in the world. In addition, a painting of a babirusa ('pig-deer') made at least 35.4kyr ago is among the earliest dated figurative depictions worldwide, if not the earliest one. Among the implications, it can now be demonstrated that humans were producing rock art by ∼40kyr ago at opposite ends of the Pleistocene Eurasian world.

Born out of place: migrant mothers and the politics of international labor

Born Out of Place: Migrant Mothers and the Politics of International Labor Nicole Constable Hong Kong: Hong Kong University Press, 2014, xvii+259p.Scholars have theoretically couched late twentieth century and early twenty-first century human migration in terms of metaphors that invoke global fluidity, risk, uncertainty, and the dismantling of previous forms of social relations. Migrants, many of whom remain nameless, are often vilified, lambasted, and treated as second-class citizens along with their children. The label often denotes persons who come from outside the body politic and it simultaneously provokes societies to demonize foreignness, associating it with contamination, risk, and anxiety. In Southeast Asia, both the Philippines and Indonesia, have intense histories of migration within the region (and beyond it) to cater to the need for flexible workers. Both nations have sent nurses, care workers, nannies, and domestic workers to Taiwan (Lan 2006), the U.S. (Rodriguez 2010), Europe, and other parts of the world where labor is required to fill gaps in the workforce. Nicole Constable's book provides a timely addition to the literature on migrants workers living overseas. It offers a very welcome and sensitive ethnography based on her many years of fieldwork in Hong Kong (HK) complimenting other recent ethnographic works that have been carried out (Matthews 2011; Knowles and Harper 2009). It focuses on migrant workers' everyday experiences and importantly, draws out not only the voices of migrant mothers and men, but also those of the children, an oftenneglected group in migration literature.The book focuses on three issues. Firstly, temporary workers to HK enter as workers (both in regards to their contracts and the obligations placed upon them by states, brokers, and other institutions) but they are never only workers. Secondly, legal frameworks, laws, and policies implemented to regulate, control, and manage migrants movement often fail in their aims. And thirdly migrants, especially those who are single mothers, enter into a migratory cycle of atonement, a self-perpetuating, precarious pattern of migration that is often the only route to escape the shame that single motherhood brings to them and their families (p. xiii). In effect, Constable questions the very heart of the system that controls migrant's movement and aims to critique current policies in not just HK, but in other regions of the world where similar policies are in place.Chapter one, A very tiny problem, presents the overall thesis of the book and takes a sensitive gendered approach toward the issue of migrant mothers in HK, their reasons to overstay and the implications of doing so. Predominately (but not exclusively) focusing on mothers who work in HK and give birth to children overseas as opposed to those who are left behind, Constable locates some of their experiences in zones of social abandonment while reminding us of the plethora of distinctions that are used to categorize migrant workers. Modifying Giorgio Agamben's notion of bare life, an effect of state power that strips of any political significance and curtails it, Constable problematizes clear-cut distinctions to scrutinize the ambiguities of the position of migrants in HK. Chapter two, Ethnography and everyday life offers an overview of the book's ethnographic approach interweaving both methodology and interviews with migrant women in HK, an approach that continues throughout the book. This is done by contextualizing her approach within two dominant streams in migration studies: one that looks at exploitation and abuse of migrant workers and another that focuses on migration as a resource (p. 23). Constable takes the approach of an engaged humanist (p. 24) with an open agenda to contribute to discussions on social justice for migrant workers. She also emphasizes that she was not a detached interviewer (p. 55); as a feminist-ethnographer-activist she juxtaposes the creative ways in which migrants work within and utilize the structures that oppress them as well as the risks they face such as giving birth, illegal abortions, rape, sex work, and domestic violence. …

Correction: Genome at Juncture of Early Human Migration: A Systematic Analysis of Two Whole Genomes and Thirteen Exomes from Kuwaiti Population Subgroup of Inferred Saudi Arabian Tribe Ancestry

Correction: Genome at Juncture of Early Human Migration: A Systematic Analysis of Two Whole Genomes and Thirteen Exomes from Kuwaiti Population Subgroup of Inferred Saudi Arabian Tribe Ancestry

Prehistoric migration in the Caribbean: past perspectives, new models and the ideal free distribution of West Indian colonization

Historically, archaeologists have pursued two basic approaches to prehistoric Caribbean colonization: those relying on historical narratives and those informed by theoretical modelling. With few exceptions, the latter have not been widely employed. Here, we introduce a behavioural ecology model used in Pacific archaeology, the ideal free distribution (IFD), to understand Caribbean migration and island settlement as a form of adaptive behaviour. We assess the sequences of Ceramic Age (post-2500 bp) colonization and overall prehistoric island colonization for fit against the predictions of the IFD using terrestrial net primary production and island area as measures of habitat suitability. We conclude that certain aspects of Caribbean colonization – the initial settlement of larger, high-quality-habitat islands and temporal pauses between migration pulses – are consistent with the IFD. Model inconsistencies observed for Ceramic Age colonization, however, are best explained in terms of the limitations of Pre-Columbian seafaring and territorial behaviour on the part of pre-existing Archaic occupants.

The population genomic landscape of human genetic structure, admixture history and local adaptation in Peninsular Malaysia.

Peninsular Malaysia is a strategic region which might have played an important role in the initial peopling and subsequent human migrations in Asia. However, the genetic diversity and history of human populations--especially indigenous populations--inhabiting this area remain poorly understood. Here, we conducted a genome-wide study using over 900,000 single nucleotide polymorphisms (SNPs) in four major Malaysian ethnic groups (MEGs; Malay, Proto-Malay, Senoi and Negrito), and made comparisons of 17 world-wide populations. Our data revealed that Peninsular Malaysia has greater genetic diversity corresponding to its role as a contact zone of both early and recent human migrations in Asia. However, each single Orang Asli (indigenous) group was less diverse with a smaller effective population size (N(e)) than a European or an East Asian population, indicating a substantial isolation of some duration for these groups. All four MEGs were genetically more similar to Asian populations than to other continental groups, and the divergence time between MEGs and East Asian populations (12,000--6,000 years ago) was also much shorter than that between East Asians and Europeans. Thus, Malaysian Orang Asli groups, despite their significantly different features, may share a common origin with the other Asian groups. Nevertheless, we identified traces of recent gene flow from non-Asians to MEGs. Finally, natural selection signatures were detected in a batch of genes associated with immune response, human height, skin pigmentation, hair and facial morphology and blood pressure in MEGs. Notable examples include SYN3 which is associated with human height in all Orang Asli groups, a height-related gene (PNPT1) and two blood pressure-related genes (CDH13 and PAX5) in Negritos. We conclude that a long isolation period, subsequent gene flow and local adaptations have jointly shaped the genetic architectures of MEGs, and this study provides insight into the peopling and human migration history in Southeast Asia.

Genome at juncture of early human migration: a systematic analysis of two whole genomes and thirteen exomes from Kuwaiti population subgroup of inferred Saudi Arabian tribe ancestry.

Population of the State of Kuwait is composed of three genetic subgroups of inferred Persian, Saudi Arabian tribe and Bedouin ancestry. The Saudi Arabian tribe subgroup traces its origin to the Najd region of Saudi Arabia. By sequencing two whole genomes and thirteen exomes from this subgroup at high coverage (>40X), we identify 4,950,724 Single Nucleotide Polymorphisms (SNPs), 515,802 indels and 39,762 structural variations. Of the identified variants, 10,098 (8.3%) exomic SNPs, 139,923 (2.9%) non-exomic SNPs, 5,256 (54.3%) exomic indels, and 374,959 (74.08%) non-exomic indels are ‘novel’. Up to 8,070 (79.9%) of the reported novel biallelic exomic SNPs are seen in low frequency (minor allele frequency <5%). We observe 5,462 known and 1,004 novel potentially deleterious nonsynonymous SNPs. Allele frequencies of common SNPs from the 15 exomes is significantly correlated with those from genotype data of a larger cohort of 48 individuals (Pearson correlation coefficient, 0.91; p <2.2×10−16). A set of 2,485 SNPs show significantly different allele frequencies when compared to populations from other continents. Two notable variants having risk alleles in high frequencies in this subgroup are: a nonsynonymous deleterious SNP (rs2108622 [19:g.15990431C>T] from CYP4F2 gene [MIM:*604426]) associated with warfarin dosage levels [MIM:#122700] required to elicit normal anticoagulant response; and a 3′ UTR SNP (rs6151429 [22:g.51063477T>C]) from ARSA gene [MIM:*607574]) associated with Metachromatic Leukodystrophy [MIM:#250100]. Hemoglobin Riyadh variant (identified for the first time in a Saudi Arabian woman) is observed in the exome data. The mitochondrial haplogroup profiles of the 15 individuals are consistent with the haplogroup diversity seen in Saudi Arabian natives, who are believed to have received substantial gene flow from Africa and eastern provenance. We present the first genome resource imperative for designing future genetic studies in Saudi Arabian tribe subgroup. The full-length genome sequences and the identified variants are available at ftp://dgr.dasmaninstitute.org and http://dgr.dasmaninstitute.org/DGR/gb.html.

Theories about evolutionary origins of human hepatitis B virus in primates and humans

IntroductionThe human hepatitis B virus causes acute and chronic hepatitis and is considered one of the most serious human health issues by the World Health Organization, causing thousands of deaths per year. There are similar viruses belonging to the Hepadnaviridae family that infect non-human primates and other mammals as well as some birds. The majority of non-human primate virus isolates were phylogenetically close to the human hepatitis B virus, but like the human genotypes, the origins of these viruses remain controversial. However, there is a possibility that human hepatitis B virus originated in primates. Knowing whether these viruses might be common to humans and primates is crucial in order to reduce the risk to humans. ObjectiveTo review the existing knowledge about the evolutionary origins of viruses of the Hepadnaviridae family in primates. MethodsThis review was done by reading several articles that provide information about the Hepadnaviridae virus family in non-human primates and humans and the possible origins and evolution of these viruses. ResultsThe evolutionary origin of viruses of the Hepadnaviridae family in primates has been dated back to several thousand years; however, recent analyses of genomic fossils of avihepadnaviruses integrated into the genomes of several avian species have suggested a much older origin of this genus. ConclusionSome hypotheses about the evolutionary origins of human hepatitis B virus have been debated since the ‘90s. One theory suggested a New World origin because of the phylogenetic co-segregation between some New World human hepatitis B virus genotypes F and H and woolly monkey human hepatitis B virus in basal sister-relationship to the Old World non-human primates and human hepatitis B virus variants. Another theory suggests an Old World origin of human hepatitis B virus, and that it would have been spread following prehistoric human migrations over 100,000 years ago. A third theory suggests a co-speciation of human hepatitis B virus in non-human primate hosts because of the proximity between the phylogeny of Old and New World non-human primate and their human hepatitis B virus variants. The importance of further research, related to the subject in South American wild fauna, is paramount and highly relevant for understanding the origin of human hepatitis B virus.

The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~7.0–7.6ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~7.0–7.6ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.

Evidence for coral island formation during rising sea level in the central Pacific Ocean

AbstractThe timing and evolution of Jabat Island, Marshall Islands, was investigated using morphostratigraphic analysis and radiometric dating. Results show the first evidence of island building in the Pacific during latter stages of Holocene sea level rise. A three‐phase model of development of Jabat is presented. Initially, rapid accumulation of coarse sediments on Jabat occurred 4800–4000 years B.P. across a reef flat higher than present level, as sea level continued to rise. During the highstand, island margins and particularly the western margin accreted vertically to 2.5–3.0 m above contemporary ridge elevations. This accumulation phase was dominated by sand‐size sediments. Phase three involved deposition of gravel ridges on the northern reef, as sea level fell to present position. Jabat has remained geomorphically stable for the past 2000 years. Findings suggest reef platforms may accommodate the oldest reef islands in atoll systems, which may have profound implications for questions of prehistoric migration through Pacific archipelagos.

Chronology of Ksar Akil (Lebanon) and Implications for the Colonization of Europe by Anatomically Modern Humans

The Out-of-Africa model holds that anatomically modern humans (AMH) evolved and dispersed from Africa into Asia, and later Europe. Palaeoanthropological evidence from the Near East assumes great importance, but AMH remains from the region are extremely scarce. ‘Egbert’, a now-lost AMH fossil from the key site of Ksar Akil (Lebanon) and ‘Ethelruda’, a recently re-discovered fragmentary maxilla from the same site, are two rare examples where human fossils are directly linked with early Upper Palaeolithic archaeological assemblages. Here we radiocarbon date the contexts from which Egbert and Ethelruda were recovered, as well as the levels above and below the findspots. In the absence of well-preserved organic materials, we primarily used marine shell beads, often regarded as indicative of behavioural modernity. Bayesian modelling allows for the construction of a chronostratigraphic framework for Ksar Akil, which supports several conclusions. The model-generated age estimates place Egbert between 40.8–39.2 ka cal BP (68.2% prob.) and Ethelruda between 42.4–41.7 ka cal BP (68.2% prob.). This indicates that Egbert is of an age comparable to that of the oldest directly-dated European AMH (Peştera cu Oase). Ethelruda is older, but on current estimates not older than the modern human teeth from Cavallo in Italy. The dating of the so-called “transitional” or Initial Upper Palaeolithic layers of the site may indicate that the passage from the Middle to Upper Palaeolithic at Ksar Akil, and possibly in the wider northern Levant, occurred later than previously estimated, casting some doubts on the assumed singular role of the region as a locus for human dispersals into Europe. Finally, tentative interpretations of the fossil's taxonomy, combined with the chronometric dating of Ethelruda's context, provides evidence that the transitional/IUP industries of Europe and the Levant, or at least some of them, may be the result of early modern human migration(s).

The fruits of migration: Understanding the ‘longue dureé’ and the socio-economic relations of the Early Transcaucasian Culture

The appearance of the Early Transcaucasian Culture (ETC) across large portions of the Near East in the 3rd millennium BC is commonly cited as one of the best archaeologically documented and broadly studied cases of a prehistoric migration. This study uses the ETC to develop a model of what happens when migrants move into regions that are already inhabited by emerging or complex societies. In particular, this study focuses on how immigrant populations can integrate themselves into indigenous communities in a physical, socio-political and economic sense, and how a migrant group’s identity can be constructed and maintained alongside these indigenous communities.Multiple lines of evidence, including settlement patterns, ceramic evidence and textual records, are used to postulate an economic niche for the ETC in viti- and viniculture, which has a long recorded history in Transcaucasia, commonly regarded as the place of origin of the ETC. The production of a consumable high status commodity such as wine by ETC immigrants provided them with the socioeconomic status that allowed them to maintain their social identity in an archaeologically visible manner in their new homelands for extended periods of time. Furthermore, the increased production of wine provided by the immigrants eventually changes the availability of this commodity and transforming its use and transforms its consumption in North Syrian societies.

African genes tracked back

Method extends archaeological and linguistic data by tracing early human migration.

Genetic Evidence of an East Asian Origin and Paleolithic Northward Migration of Y-chromosome Haplogroup N

The Y-chromosome haplogroup N-M231 (Hg N) is distributed widely in eastern and central Asia, Siberia, as well as in eastern and northern Europe. Previous studies suggested a counterclockwise prehistoric migration of Hg N from eastern Asia to eastern and northern Europe. However, the root of this Y chromosome lineage and its detailed dispersal pattern across eastern Asia are still unclear. We analyzed haplogroup profiles and phylogeographic patterns of 1,570 Hg N individuals from 20,826 males in 359 populations across Eurasia. We first genotyped 6,371 males from 169 populations in China and Cambodia, and generated data of 360 Hg N individuals, and then combined published data on 1,210 Hg N individuals from Japanese, Southeast Asian, Siberian, European and Central Asian populations. The results showed that the sub-haplogroups of Hg N have a distinct geographical distribution. The highest Y-STR diversity of the ancestral Hg N sub-haplogroups was observed in the southern part of mainland East Asia, and further phylogeographic analyses supports an origin of Hg N in southern China. Combined with previous data, we propose that the early northward dispersal of Hg N started from southern China about 21 thousand years ago (kya), expanding into northern China 12–18 kya, and reaching further north to Siberia about 12–14 kya before a population expansion and westward migration into Central Asia and eastern/northern Europe around 8.0–10.0 kya. This northward migration of Hg N likewise coincides with retreating ice sheets after the Last Glacial Maximum (22–18 kya) in mainland East Asia.

Clinal distribution of human genomic diversity across the Netherlands despite archaeological evidence for genetic discontinuities in Dutch population history

BackgroundThe presence of a southeast to northwest gradient across Europe in human genetic diversity is a well-established observation and has recently been confirmed by genome-wide single nucleotide polymorphism (SNP) data. This pattern is traditionally explained by major prehistoric human migration events in Palaeolithic and Neolithic times. Here, we investigate whether (similar) spatial patterns in human genomic diversity also occur on a micro-geographic scale within Europe, such as in the Netherlands, and if so, whether these patterns could also be explained by more recent demographic events, such as those that occurred in Dutch population history.MethodsWe newly collected data on a total of 999 Dutch individuals sampled at 54 sites across the country at 443,816 autosomal SNPs using the Genome-Wide Human SNP Array 5.0 (Affymetrix). We studied the individual genetic relationships by means of classical multidimensional scaling (MDS) using different genetic distance matrices, spatial ancestry analysis (SPA), and ADMIXTURE software. We further performed dedicated analyses to search for spatial patterns in the genomic variation and conducted simulations (SPLATCHE2) to provide a historical interpretation of the observed spatial patterns.ResultsWe detected a subtle but clearly noticeable genomic population substructure in the Dutch population, allowing differentiation of a north-eastern, central-western, central-northern and a southern group. Furthermore, we observed a statistically significant southeast to northwest cline in the distribution of genomic diversity across the Netherlands, similar to earlier findings from across Europe. Simulation analyses indicate that this genomic gradient could similarly be caused by ancient as well as by the more recent events in Dutch history.ConclusionsConsidering the strong archaeological evidence for genetic discontinuity in the Netherlands, we interpret the observed clinal pattern of genomic diversity as being caused by recent rather than ancient events in Dutch population history. We therefore suggest that future human population genetic studies pay more attention to recent demographic history in interpreting genetic clines. Furthermore, our study demonstrates that genetic population substructure is detectable on a small geographic scale in Europe despite recent demographic events, a finding we consider potentially relevant for future epidemiological and forensic studies.

How People Moved among Ancient Societies: Broadening the View

ABSTRACTArchaeologists have made great strides in understanding prehistoric migration, yet they have tended to focus on only part of the continuum of human movement. In nonstate societies, individuals and groups moved frequently across social and environmental boundaries for a range of reasons. Although archaeologists are well aware of the fluid nature of social boundaries, we are only beginning to use this knowledge to understand human movement. I use ethnohistoric and ethnographic examples to show that people in nonstate societies moved frequently as a result of warfare and captive taking, processes of fission and fusion, and random demographic events typical of small‐scale societies. Such movement was often hurried, sometimes coerced, and decision making could be constrained by social factors beyond migrants’ control. Illustrated with a case study from the American Southwest, I argue here that consideration of such forms of movement can significantly improve our interpretations of the past.

Genetic Evidence of Paleolithic Colonization and Neolithic Expansion of Modern Humans on the Tibetan Plateau

Tibetans live on the highest plateau in the world, their current population size is approximately 5 million, and most of them live at an altitude exceeding 3,500 m. Therefore, the Tibetan Plateau is a remarkable area for cultural and biological studies of human population history. However, the chronological profile of the Tibetan Plateau's colonization remains an unsolved question of human prehistory. To reconstruct the prehistoric colonization and demographic history of modern humans on the Tibetan Plateau, we systematically sampled 6,109 Tibetan individuals from 41 geographic populations across the entire region of the Tibetan Plateau and analyzed the phylogeographic patterns of both paternal (n = 2,354) and maternal (n = 6,109) lineages as well as genome-wide single nucleotide polymorphism markers (n = 50) in Tibetan populations. We found that there have been two distinct, major prehistoric migrations of modern humans into the Tibetan Plateau. The first migration was marked by ancient Tibetan genetic signatures dated to approximately 30,000 years ago, indicating that the initial peopling of the Tibetan Plateau by modern humans occurred during the Upper Paleolithic rather than Neolithic. We also found evidences for relatively young (only 7-10 thousand years old) shared Y chromosome and mitochondrial DNA haplotypes between Tibetans and Han Chinese, suggesting a second wave of migration during the early Neolithic. Collectively, the genetic data indicate that Tibetans have been adapted to a high altitude environment since initial colonization of the Tibetan Plateau in the early Upper Paleolithic, before the last glacial maximum, followed by a rapid population expansion that coincided with the establishment of farming and yak pastoralism on the Plateau in the early Neolithic.

Hints of Unique Genetic Effects for Type 2 Diabetes in India

The prevalence of type 2 diabetes (T2D) is rising rapidly worldwide. In September 2012, the World Health Organization reported a global prevalence exceeding 300 million people, predicting a further 60–70% increase by the year 2030 (1). One of the largest absolute increases is expected to occur in India, with the International Diabetes Federation estimating that India alone will have 100 million people with diabetes by 2030 (2). About 90% of these will have T2D. Increased food consumption and decreased physical activity represent major contributors to the growing Indian T2D epidemic, reflecting ongoing economic transitions and widespread embrace of a Western lifestyle. But T2D risk also has a substantial genetic component and evidence indicates that Indians may be more susceptible to developing insulin resistance and T2D compared with European-ancestry individuals of equivalent age and BMI (3–5), suggesting the possibility of population-specific genetic or epigenetic risk factors. A recent, comprehensive genetic study provided compelling evidence for global genetic differentiation of T2D risk. In a survey of thousands of confirmed genetic associations, risk alleles for T2D demonstrated the most extreme population frequency differentiation among twelve common diseases studied (6). A clear gradient of T2D risk allele frequencies along continental paths of early human migration was evident, suggesting potential population-specific evolutionary adaptation to agricultural …

Evaluation of early stage human bone marrow stromal proliferation, cell migration and osteogenic differentiation on μ-MIM structured stainless steel surfaces

It is well established that surface topography greatly affect cell-surface interactions. In a recent study we showed that microstructured stainless steel surfaces characterized by the presence of defined hexagonally arranged hemisphere-like structures significantly affected cell architecture (shape and focal adhesion size) of primary human bone mesenchymal stromal cells. This study aimed at further investigating the influence these microstructures (microcline protruding hemispheres) on critical aspects of cell behaviour namely; proliferation, migration and osteogenic differentiation. As with previously reported data, we used primary human bone mesenchymal stromal cells to investigate such effects at an early stage in vitro. Cells of different patients were utilised for cell migration studies. Our data showed that an increase in cell proliferation was exhibited as a function of surface topography (hemispheres). Cell migration velocity also varied as a function of surface topography on patient specific basis and seems to relate to the differentiated state of the seeded cell population (as demonstrated by bALP positivity). Osteogenic differentiation, however, did not exhibit significant variations (both up and down-regulation) as a function of both surface topography and time in culture.

DHCR7 mutations linked to higher vitamin D status allowed early human migration to Northern latitudes

BackgroundVitamin D is essential for a wide range of physiological processes including immune function and calcium homeostasis. Recent investigations have identified candidate genes which are strongly linked to concentrations of 25-hydroxyvitamin D. Since there is insufficient UVB radiation to induce year-round cutaneous synthesis of vitamin D at latitudes distant from the equator it is likely that these genes were subject to forces of natural selection. We used the fixation index (FST) to measure differences in allele frequencies in 993 individuals from ten populations to identify the presence of evolutionary selection in genes in the vitamin D pathway. We then explored the length of haplotypes in chromosomes to confirm recent positive selection.ResultsWe find evidence of positive selection for DHCR7, which governs availability of 7-dehydrocholesterol for conversion to vitamin D3 by the action of sunlight on the skin. We show that extended haplotypes related to vitamin D status are highly prevalent at Northern latitudes (Europe 0.72, Northeast Asia 0.41). The common DHCR7 haplotype underwent a recent selective sweep in Northeast Asia, with relative extended haplotype homozygosity of 5.03 (99th percentile). In contrast, CYP2R1, which 25-hydroxylates vitamin D, is under balancing selection and we found no evidence of recent selection pressure on GC, which is responsible for vitamin D transport.ConclusionsOur results suggest that genetic variation in DHCR7 is the major adaptation affecting vitamin D metabolism in recent evolutionary history which helped early humans to avoid severe vitamin D deficiency and enabled them to inhabit areas further from the equator.