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1.
Proc Natl Acad Sci U S A ; 121(26): e2405889121, 2024 Jun 25.
Article in English | MEDLINE | ID: mdl-38889149

ABSTRACT

Neandertals and Denisovans, having inhabited distinct regions in Eurasia and possibly Oceania for over 200,000 y, experienced ample time to adapt to diverse environmental challenges these regions presented. Among present-day human populations, Papua New Guineans (PNG) stand out as one of the few carrying substantial amounts of both Neandertal and Denisovan DNA, a result of past admixture events with these archaic human groups. This study investigates the distribution of introgressed Denisovan and Neandertal DNA within two distinct PNG populations, residing in the highlands of Mt Wilhelm and the lowlands of Daru Island. These locations exhibit unique environmental features, some of which may parallel the challenges that archaic humans once confronted and adapted to. Our results show that PNG highlanders carry higher levels of Denisovan DNA compared to PNG lowlanders. Among the Denisovan-like haplotypes with higher frequencies in highlander populations, those exhibiting the greatest frequency difference compared to lowlander populations also demonstrate more pronounced differences in population frequencies than frequency-matched nonarchaic variants. Two of the five most highly differentiated of those haplotypes reside in genomic areas linked to brain development genes. Conversely, Denisovan-like haplotypes more frequent in lowlanders overlap with genes associated with immune response processes. Our findings suggest that Denisovan DNA has provided genetic variation associated with brain biology and immune response to PNG genomes, some of which might have facilitated adaptive processes to environmental challenges.


Subject(s)
Haplotypes , Neanderthals , Papua New Guinea , Humans , Animals , Neanderthals/genetics , Adaptation, Physiological/genetics , Genetics, Population
2.
Nat Commun ; 15(1): 3352, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38688933

ABSTRACT

Highlanders and lowlanders of Papua New Guinea have faced distinct environmental stress, such as hypoxia and environment-specific pathogen exposure, respectively. In this study, we explored the top genomics regions and the candidate driver SNPs for selection in these two populations using newly sequenced whole-genomes of 54 highlanders and 74 lowlanders. We identified two candidate SNPs under selection - one in highlanders, associated with red blood cell traits and another in lowlanders, which is associated with white blood cell count - both potentially influencing the heart rate of Papua New Guineans in opposite directions. We also observed four candidate driver SNPs that exhibit linkage disequilibrium with an introgressed haplotype, highlighting the need to explore the possibility of adaptive introgression within these populations. This study reveals that the signatures of positive selection in highlanders and lowlanders of Papua New Guinea align closely with the challenges they face, which are specific to their environments.


Subject(s)
Altitude , Haplotypes , Linkage Disequilibrium , Polymorphism, Single Nucleotide , Selection, Genetic , Papua New Guinea , Humans , Genome, Human , Genetics, Population
3.
Mol Ecol ; 32(10): 2551-2564, 2023 05.
Article in English | MEDLINE | ID: mdl-36151926

ABSTRACT

The oral microbiota is a highly complex and diversified part of the human microbiome. Being located at the interface between the human body and the exterior environment, this microbiota can deepen our understanding of the environmental impacts on the global status of human health. This research topic has been well addressed in Westernized populations, but these populations only represent a fraction of human diversity. Papua New Guinea hosts very diverse environments and one of the most unique human biological diversities worldwide. In this study we performed the first known characterization of the oral microbiome in 85 Papua New Guinean individuals living in different environments, using a qualitative and quantitative approach. We found a significant geographical structure of the Papua New Guineans oral microbiome, especially in the groups most isolated from urban spaces. In comparison to other global populations, two bacterial genera related to iron absorption were significantly more abundant in Papua New Guineans and Aboriginal Australians, which suggests a shared oral microbiome signature. Further studies will be needed to confirm and explore this possible regional-specific oral microbiome profile.


Subject(s)
Microbiota , Mouth , Humans , Australia , Geography , Microbiota/genetics , Papua New Guinea , Mouth/microbiology
4.
PLoS Genet ; 18(12): e1010470, 2022 12.
Article in English | MEDLINE | ID: mdl-36480515

ABSTRACT

Modern humans have admixed with multiple archaic hominins. Papuans, in particular, owe up to 5% of their genome to Denisovans, a sister group to Neanderthals whose remains have only been identified in Siberia and Tibet. Unfortunately, the biological and evolutionary significance of these introgression events remain poorly understood. Here we investigate the function of both Denisovan and Neanderthal alleles characterised within a set of 56 genomes from Papuan individuals. By comparing the distribution of archaic and non-archaic variants we assess the consequences of archaic admixture across a multitude of different cell types and functional elements. We observe an enrichment of archaic alleles within cis-regulatory elements and transcribed regions of the genome, with Denisovan variants strongly affecting elements active within immune-related cells. We identify 16,048 and 10,032 high-confidence Denisovan and Neanderthal variants that fall within annotated cis-regulatory elements and with the potential to alter the affinity of multiple transcription factors to their cognate DNA motifs, highlighting a likely mechanism by which introgressed DNA can impact phenotypes. Lastly, we experimentally validate these predictions by testing the regulatory potential of five Denisovan variants segregating within Papuan individuals, and find that two are associated with a significant reduction of transcriptional activity in plasmid reporter assays. Together, these data provide support for a widespread contribution of archaic DNA in shaping the present levels of modern human genetic diversity, with different archaic ancestries potentially affecting multiple phenotypic traits within non-Africans.


Subject(s)
Evolution, Molecular , Hominidae , Immune System , Neanderthals , Humans , Hominidae/genetics , Neanderthals/genetics , Papua New Guinea
5.
iScience ; 25(7): 104583, 2022 Jul 15.
Article in English | MEDLINE | ID: mdl-35880026

ABSTRACT

As human populations left Asia to first settle in Oceania around 50,000 years ago, they entered a territory ecologically separated from the Old World for millions of years. We analyzed genomic data of 239 modern Oceanian individuals to detect and date signals of selection specific to this region. Combining both relative and absolute dating approaches, we identified a strong selection pattern between 52,000 and 54,000 years ago in the genomes of descendants of the first settlers of Sahul. This strikingly corresponds to the dates of initial settlement as inferred from archaeological evidence. Loci under selection during this period, some showing enrichment in Denisovan ancestry, overlap genes involved in the immune response and diet, especially based on plants. Pathogens and natural resources, especially from endemic plants, therefore appear to have acted as strong selective pressures on the genomes of the first settlers of Sahul.

6.
Nucleic Acids Res ; 50(12): 6735-6752, 2022 07 08.
Article in English | MEDLINE | ID: mdl-35713545

ABSTRACT

We analysed DNA methylation data from 30 datasets comprising 3474 individuals, 19 tissues and 8 ethnicities at CpGs covered by the Illumina450K array. We identified 4143 hypervariable CpGs ('hvCpGs') with methylation in the top 5% most variable sites across multiple tissues and ethnicities. hvCpG methylation was influenced but not determined by genetic variation, and was not linked to probe reliability, epigenetic drift, age, sex or cell heterogeneity effects. hvCpG methylation tended to covary across tissues derived from different germ-layers and hvCpGs were enriched for proximity to ERV1 and ERVK retrovirus elements. hvCpGs were also enriched for loci previously associated with periconceptional environment, parent-of-origin-specific methylation, and distinctive methylation signatures in monozygotic twins. Together, these properties position hvCpGs as strong candidates for studying how stochastic and/or environmentally influenced DNA methylation states which are established in the early embryo and maintained stably thereafter can influence life-long health and disease.


Subject(s)
DNA Methylation , Embryo, Mammalian , Humans , DNA Methylation/genetics , Reproducibility of Results , Embryo, Mammalian/metabolism , CpG Islands , Ethnicity
7.
Mol Biol Evol ; 39(3)2022 03 02.
Article in English | MEDLINE | ID: mdl-35294555

ABSTRACT

Island Southeast Asia (ISEA) and Oceania host one of the world's richest assemblages of human phenotypic, linguistic, and cultural diversity. Despite this, the region's male genetic lineages are globally among the last to remain unresolved. We compiled ∼9.7 Mb of Y chromosome (chrY) sequence from a diverse sample of over 380 men from this region, including 152 first reported here. The granularity of this data set allows us to fully resolve and date the regional chrY phylogeny. This new high-resolution tree confirms two main population bursts: multiple rapid diversifications following the region's initial settlement ∼50 kya, and extensive expansions <6 kya. Notably, ∼40-25 kya the deep rooting local lineages of C-M130, M-P256, and S-B254 show almost no further branching events in ISEA, New Guinea, and Australia, matching a similar pause in diversification seen in maternal mitochondrial DNA lineages. The main local lineages start diversifying ∼25 kya, at the time of the last glacial maximum. This improved chrY topology highlights localized events with important historical implications, including pre-Holocene contact between Mainland and ISEA, potential interactions between Australia and the Papuan world, and a sustained period of diversification following the flooding of the ancient Sunda and Sahul continents as the insular landscape observed today formed. The high-resolution phylogeny of the chrY presented here thus enables a detailed exploration of past isolation, interaction, and change in one of the world's least understood regions.


Subject(s)
Asian People , DNA, Mitochondrial , Asia, Southeastern , DNA, Mitochondrial/genetics , Humans , Male , Mitochondria/genetics , Phylogeny
8.
Mol Biol Evol ; 38(11): 5107-5121, 2021 10 27.
Article in English | MEDLINE | ID: mdl-34383935

ABSTRACT

The settlement of Sahul, the lost continent of Oceania, remains one of the most ancient and debated human migrations. Modern New Guineans inherited a unique genetic diversity tracing back 50,000 years, and yet there is currently no model reconstructing their past population dynamics. We generated 58 new whole-genome sequences from Papua New Guinea, filling geographical gaps in previous sampling, specifically to address alternative scenarios of the initial migration to Sahul and the settlement of New Guinea. Here, we present the first genomic models for the settlement of northeast Sahul considering one or two migrations from Wallacea. Both models fit our data set, reinforcing the idea that ancestral groups to New Guinean and Indigenous Australians split early, potentially during their migration in Wallacea where the northern route could have been favored. The earliest period of human presence in Sahul was an era of interactions and gene flow between related but already differentiated groups, from whom all modern New Guineans, Bismarck islanders, and Indigenous Australians descend. The settlement of New Guinea was probably initiated from its southeast region, where the oldest archaeological sites have been found. This was followed by two migrations into the south and north lowlands that ultimately reached the west and east highlands. We also identify ancient gene flows between populations in New Guinea, Australia, East Indonesia, and the Bismarck Archipelago, emphasizing the fact that the anthropological landscape during the early period of Sahul settlement was highly dynamic rather than the traditional view of extensive isolation.


Subject(s)
Ethnicity , Human Migration , Australia , Humans , Papua New Guinea , Phylogeny
9.
Gene ; 800: 145845, 2021 Oct 20.
Article in English | MEDLINE | ID: mdl-34274465

ABSTRACT

The betel nut (Areca catechu L., Arecaceae) is a monoecious cultivated palm tree that is widespread in tropical regions. It is mainly cultivated for producing areca nuts, from which seeds are extracted and chewed by local populations principally in the Indo-Pacific region. Seeds contain alkaloids which are central nervous system stimulants and are highly addictive. Wild relatives of the betel nut are distributed in South Asia and Australasia, with ca. 40-50 Areca species currently recognized. The geographic origin(s) of the betel nut and its subsequent diffusion and diversification remains poorly documented. Here, a genome skimming approach was applied to screen nucleotidic variation in the most abundant genomic regions. Low coverage sequencing data allowed us to assemble full plastomes, mitochondrial regions (either full mitogenomes or the full set of mitochondrial genes) and the nuclear ribosomal DNA cluster for nine representatives of the Areca genus collected in the field and herbarium collections (including a 182-years old specimen collected during the Dumont d'Urville's expedition). These three genomic compartments provided similar phylogenetic signals, and revealed very low genomic diversity in our sample of cultivated betel nut. We finally developed a genotyping method targeting 34 plastid DNA microsatellites. This plastome profiling approach is useful for tracing the spread of matrilineages, and in combination with nuclear genomic data, can resolve the history of the betel nut. Our method also proves to be efficient for analyzing herbarium specimens, even those collected >100 years ago.


Subject(s)
Areca/genetics , Gene Expression Profiling/methods , Genome, Plant , Genome, Plastid , DNA, Mitochondrial , Microsatellite Repeats , Phylogeny
10.
PLoS One ; 16(7): e0253921, 2021.
Article in English | MEDLINE | ID: mdl-34288918

ABSTRACT

OBJECTIVES: Altitude is one of the most demanding environmental pressures for human populations. Highlanders from Asia, America and Africa have been shown to exhibit different biological adaptations, but Oceanian populations remain understudied [Woolcock et al., 1972; Cotes et al., 1974; Senn et al., 2010]. We tested the hypothesis that highlanders phenotypically differ from lowlanders in Papua New Guinea, as a result of inhabiting the highest mountains in Oceania for at least 20,000 years. MATERIALS AND METHODS: We collected data for 13 different phenotypes related to altitude for 162 Papua New Guineans living at high altitude (Mont Wilhelm, 2,300-2,700 m above sea level (a.s.l.) and low altitude (Daru, <100m a.s.l.). Multilinear regressions were performed to detect differences between highlanders and lowlanders for phenotypic measurements related to body proportions, pulmonary function, and the circulatory system. RESULTS: Six phenotypes were significantly different between Papua New Guinean highlanders and lowlanders. Highlanders show shorter height (p-value = 0.001), smaller waist circumference (p-value = 0.002), larger Forced Vital Capacity (FVC) (p-value = 0.008), larger maximal (p-value = 3.20e -4) and minimal chest depth (p-value = 2.37e -5) and higher haemoglobin concentration (p-value = 3.36e -4). DISCUSSION: Our study reports specific phenotypes in Papua New Guinean highlanders potentially related to altitude adaptation. Similar to other human groups adapted to high altitude, the evolutionary history of Papua New Guineans appears to have also followed an adaptive biological strategy for altitude.


Subject(s)
Acclimatization/physiology , Altitude , Black People/statistics & numerical data , Indigenous Peoples/statistics & numerical data , Somatotypes/physiology , Adult , Anthropometry , Body Height , Female , Forced Expiratory Volume , Hemodynamics , Hemoglobins/analysis , Humans , Male , Middle Aged , Papua New Guinea , Phenotype , Thorax/anatomy & histology , Vital Capacity , Waist Circumference
11.
Am J Phys Anthropol ; 173(3): 423-436, 2020 11.
Article in English | MEDLINE | ID: mdl-32812238

ABSTRACT

OBJECTIVES: Archeological evidence shows that first nomadic pastoralists came to the African Sahel from northeastern Sahara, where milking is reported by ~7.5 ka. A second wave of pastoralists arrived with the expansion of Arabic tribes in 7th-14th century CE. All Sahelian pastoralists depend on milk production but genetic diversity underlying their lactase persistence (LP) is poorly understood. MATERIALS AND METHODS: We investigated SNP variants associated with LP in 1,241 individuals from 29 mostly pastoralist populations in the Sahel. Then, we analyzed six SNPs in the neighboring fragment (419 kb) in the Fulani and Tuareg with the -13910*T mutation, reconstructed haplotypes, and calculated expansion age and growth rate of this variant. RESULTS: Our results reveal a geographic localization of two different LP variants in the Sahel: -13910*T west of Lake Chad (Fulani and Tuareg pastoralists) and -13915*G east of there (mostly Arabic-speaking pastoralists). We show that -13910*T has a more diversified haplotype background among the Fulani than among the Tuareg and that the age estimate for expansion of this variant among the Fulani (~8.5 ka) corresponds to introduction of cattle to the area. CONCLUSIONS: This is the first study showing that the "Eurasian" LP allele -13910*T is widespread both in northern Europe and in the Sahel; however, it is limited to pastoralists in the Sahel. Since the Fulani haplotype with -13910*T is shared with contemporary Eurasians, its origin could be in a region encompassing the Near East and northeastern Africa in a population ancestral to both Saharan pastoralists and European farmers.


Subject(s)
Black People , Ethnicity , Lactase/genetics , Polymorphism, Single Nucleotide/genetics , Africa, Northern , Animals , Anthropology, Physical , Arabs/genetics , Arabs/statistics & numerical data , Black People/genetics , Black People/statistics & numerical data , Diet , Ethnicity/genetics , Ethnicity/statistics & numerical data , Haplotypes , Humans , Milk , Transients and Migrants , White People/genetics , White People/statistics & numerical data
12.
J Hum Genet ; 65(10): 875-887, 2020 Oct.
Article in English | MEDLINE | ID: mdl-32483274

ABSTRACT

New Guineans represent one of the oldest locally continuous populations outside Africa, harboring among the greatest linguistic and genetic diversity on the planet. Archeological and genetic evidence suggest that their ancestors reached Sahul (present day New Guinea and Australia) by at least 55,000 years ago (kya). However, little is known about this early settlement phase or subsequent dispersal and population structuring over the subsequent period of time. Here we report 379 complete Papuan mitochondrial genomes from across Papua New Guinea, which allow us to reconstruct the phylogenetic and phylogeographic history of northern Sahul. Our results support the arrival of two groups of settlers in Sahul within the same broad time window (50-65 kya), each carrying a different set of maternal lineages and settling Northern and Southern Sahul separately. Strong geographic structure in northern Sahul remains visible today, indicating limited dispersal over time despite major climatic, cultural, and historical changes. However, following a period of isolation lasting nearly 20 ky after initial settlement, environmental changes postdating the Last Glacial Maximum stimulated diversification of mtDNA lineages and greater interactions within and beyond Northern Sahul, to Southern Sahul, Wallacea and beyond. Later, in the Holocene, populations from New Guinea, in contrast to those of Australia, participated in early interactions with incoming Asian populations from Island Southeast Asia and continuing into Oceania.


Subject(s)
Ethnicity/genetics , Human Migration/history , Adult , Asia, Southeastern , Australia , Ethnicity/history , Female , Genome, Mitochondrial , Geological Phenomena , Haplotypes/genetics , History, Ancient , Humans , Likelihood Functions , Male , New Guinea , Papua New Guinea , Phylogeny , Phylogeography , Tasmania
13.
J Anal Toxicol ; 44(1): 41-48, 2020 Jan 07.
Article in English | MEDLINE | ID: mdl-31263904

ABSTRACT

Betel nut is the fruit of Areca palm, growing in Papua New Guinea. Mixed with limestone and stick mustard, arecoline and guvacoline, which are present in betel nut, are hydrolyzed into arecaidine and guvacine, respectively. As part of the study on dietary habits of Papuans residents, our laboratory was asked to analyze the four alkaloids in hair to document long-term exposure. Hair samples were collected from 19 adult subjects (males = 11; females = 8), by some of the authors, and were sent to the laboratory for analysis. The four alkaloids have very similar chemical structures. In order to accurately identify the drugs, two methods were developed. First, the compounds were identified using an ultra-high-performance liquid chromatography system coupled to time-of-flight mass spectrometry. Then, they were quantified by an ultra-high-performance liquid chromatography system coupled to tandem mass spectrometry. After decontamination with dichloromethane, hair samples were cut into very small segments and 20 mg were incubated in methanol for 2 h 30 min in an ultrasound bath. After cooling, the methanol was evaporated to dryness in presence of 20-µL octanol to prevent volatilization. Nicotine-d4 was used as an internal standard. Linearity was observed for concentrations ranging from the limit of quantification to 20 ng/mg for arecoline, arecaidine, guvacine and guvacoline. Measured concentrations were in the range 60 pg/mg to 18 ng/mg for arecoline (n = 19), 14 pg/mg to 2.5 ng/mg for guvacoline (n = 11), 63 pg/mg to 3.8 ng/mg for arecaidine (n = 11) and 100 pg/mg to 3.2 ng/mg for guvacine (n = 6). There was no correlation between concentrations of arecoline and arecaidine (ratio from 0.01 to 0.18) and guvacoline and guvacine (ratio from 0.06 to 3.50). However, the identification of these substances in hair is a good marker of consumption of betel nut and allows us to document a local practice that remains difficult to evaluate just by questioning.


Subject(s)
Alkaloids/analysis , Areca , Hair/chemistry , Substance Abuse Detection/methods , Chromatography, High Pressure Liquid , Chromatography, Liquid , Humans , Substance-Related Disorders , Tandem Mass Spectrometry
14.
Cell ; 177(4): 1010-1021.e32, 2019 05 02.
Article in English | MEDLINE | ID: mdl-30981557

ABSTRACT

Genome sequences are known for two archaic hominins-Neanderthals and Denisovans-which interbred with anatomically modern humans as they dispersed out of Africa. We identified high-confidence archaic haplotypes in 161 new genomes spanning 14 island groups in Island Southeast Asia and New Guinea and found large stretches of DNA that are inconsistent with a single introgressing Denisovan origin. Instead, modern Papuans carry hundreds of gene variants from two deeply divergent Denisovan lineages that separated over 350 thousand years ago. Spatial and temporal structure among these lineages suggest that introgression from one of these Denisovan groups predominantly took place east of the Wallace line and continued until near the end of the Pleistocene. A third Denisovan lineage occurs in modern East Asians. This regional mosaic suggests considerable complexity in archaic contact, with modern humans interbreeding with multiple Denisovan groups that were geographically isolated from each other over deep evolutionary time.


Subject(s)
Genetic Introgression/genetics , Haplotypes/genetics , Hominidae/genetics , Animals , Asian People/genetics , Biological Evolution , Gene Flow , Genetic Variation/genetics , Genome, Human/genetics , Humans , Indonesia , Neanderthals/genetics , Oceania
15.
Genome Biol Evol ; 11(3): 748-758, 2019 03 01.
Article in English | MEDLINE | ID: mdl-30715341

ABSTRACT

The Austronesian dispersal across the Indonesian Ocean to Madagascar and the Comoros has been well documented, but in an unexplained anomaly, few to no traces have been found of the Austronesian expansion in East Africa or the Arabian Peninsula. To revisit this peculiarity, we surveyed the Western Indian Ocean rim populations to identify potential Austronesian genetic ancestry. We generated full mitochondrial DNA genomes and genome-wide genotyping data for these individuals and compared them with the Banjar, the Indonesian source population of the westward Austronesian dispersal. We find strong support for Asian genetic contributions to maternal lineages and autosomal variation in modern day Somalia and Yemen. Surprisingly, this input reveals two apparently different geographic origins and timings of admixture for the Austronesian contact; one at a very early phase (likely associated with the early Austronesian dispersals), and a later movement dating to the end of nineteenth century. These Austronesian gene flows come, respectively, from Madagascar and directly from an unidentified location in Island Southeast Asia. This result reveals a far more complex dynamic of Austronesian dispersals through the Western Indian Ocean than has previously been understood and suggests that Austronesian movements within the Indian Ocean may have been part of a lengthy process, probably continuing well into the modern era.


Subject(s)
Gene Flow , Genome, Mitochondrial , Human Migration , Africa, Eastern , Arabia , Borneo , Humans , Indian Ocean Islands
16.
Mol Biol Evol ; 36(3): 575-586, 2019 03 01.
Article in English | MEDLINE | ID: mdl-30649405

ABSTRACT

The Arabian Peninsula (AP) was an important crossroad between Africa, Asia, and Europe, being the cradle of the structure defining these main human population groups, and a continuing path for their admixture. The screening of 741,000 variants in 420 Arabians and 80 Iranians allowed us to quantify the dominant sub-Saharan African admixture in the west of the peninsula, whereas South Asian and Levantine/European influence was stronger in the east, leading to a rift between western and eastern sides of the Peninsula. Dating of the admixture events indicated that Indian Ocean slave trade and Islamization periods were important moments in the genetic makeup of the region. The western-eastern axis was also observable in terms of positive selection of diversity conferring lactose tolerance, with the West AP developing local adaptation and the East AP acquiring the derived allele selected in European populations and existing in South Asia. African selected malaria resistance through the DARC gene was enriched in all Arabian genomes, especially in the western part. Clear European influences associated with skin and eye color were equally frequent across the Peninsula.


Subject(s)
Arabs/genetics , Gene Flow , Genome, Human , Humans , Middle East , Phylogeography
17.
Nat Commun ; 9(1): 932, 2018 03 02.
Article in English | MEDLINE | ID: mdl-29500350

ABSTRACT

While admixed populations offer a unique opportunity to detect selection, the admixture in most of the studied populations occurred too recently to produce conclusive signals. By contrast, Malagasy populations originate from admixture between Asian and African populations that occurred ~27 generations ago, providing power to detect selection. We analyze local ancestry across the genomes of 700 Malagasy and identify a strong signal of recent positive selection, with an estimated selection coefficient >0.2. The selection is for African ancestry and affects 25% of chromosome 1, including the Duffy blood group gene. The null allele at this gene provides resistance to Plasmodium vivax malaria, and previous studies have suggested positive selection for this allele in the Malagasy population. This selection event also influences numerous other genes implicated in immunity, cardiovascular diseases, and asthma and decreases the Asian ancestry genome-wide by 10%, illustrating the role played by selection in recent human history.


Subject(s)
Genome, Human , Genome-Wide Association Study , Selection, Genetic , Black People/genetics , Duffy Blood-Group System/genetics , Humans , Madagascar , Spatial Analysis
18.
Am J Hum Genet ; 102(1): 58-68, 2018 01 04.
Article in English | MEDLINE | ID: mdl-29304377

ABSTRACT

At the dawn of the second millennium, the expansion of the Indian Ocean trading network aligned with the emergence of an outward-oriented community along the East African coast to create a cosmopolitan cultural and trading zone known as the Swahili Corridor. On the basis of analyses of new genome-wide genotyping data and uniparental data in 276 individuals from coastal Kenya and the Comoros islands, along with large-scale genetic datasets from the Indian Ocean rim, we reconstruct historical population dynamics to show that the Swahili Corridor is largely an eastern Bantu genetic continuum. Limited gene flows from the Middle East can be seen in Swahili and Comorian populations at dates corresponding to historically documented contacts. However, the main admixture event in southern insular populations, particularly Comorian and Malagasy groups, occurred with individuals from Island Southeast Asia as early as the 8th century, reflecting an earlier dispersal from this region. Remarkably, our results support recent archaeological and linguistic evidence-based suggestions that the Comoros archipelago was the earliest location of contact between Austronesian and African populations in the Swahili Corridor.


Subject(s)
Gene Flow , Genetics, Population , Asia , Australia , Comoros , Genetic Variation , Humans , Kenya , Polymorphism, Single Nucleotide/genetics
19.
Proc Natl Acad Sci U S A ; 114(32): E6498-E6506, 2017 08 08.
Article in English | MEDLINE | ID: mdl-28716916

ABSTRACT

Although situated ∼400 km from the east coast of Africa, Madagascar exhibits cultural, linguistic, and genetic traits from both Southeast Asia and Eastern Africa. The settlement history remains contentious; we therefore used a grid-based approach to sample at high resolution the genomic diversity (including maternal lineages, paternal lineages, and genome-wide data) across 257 villages and 2,704 Malagasy individuals. We find a common Bantu and Austronesian descent for all Malagasy individuals with a limited paternal contribution from Europe and the Middle East. Admixture and demographic growth happened recently, suggesting a rapid settlement of Madagascar during the last millennium. However, the distribution of African and Asian ancestry across the island reveals that the admixture was sex biased and happened heterogeneously across Madagascar, suggesting independent colonization of Madagascar from Africa and Asia rather than settlement by an already admixed population. In addition, there are geographic influences on the present genomic diversity, independent of the admixture, showing that a few centuries is sufficient to produce detectable genetic structure in human populations.


Subject(s)
Asian People/genetics , Black People/genetics , Ethnicity/genetics , Genetic Variation , Genome, Human , Genome-Wide Association Study , Aged , Female , Humans , Madagascar/ethnology , Male , Middle Aged
20.
Sci Rep ; 7(1): 2919, 2017 06 07.
Article in English | MEDLINE | ID: mdl-28592861

ABSTRACT

The Indian Ocean has long been a hub of interacting human populations. Following land- and sea-based routes, trade drove cultural contacts between far-distant ethnic groups in Asia, India, the Middle East and Africa, creating one of the world's first proto-globalized environments. However, the extent to which population mixing was mediated by trade is poorly understood. Reconstructing admixture times from genomic data in 3,006 individuals from 187 regional populations reveals a close association between bouts of human migration and trade volumes during the last 2,000 years across the Indian Ocean trading system. Temporal oscillations in trading activity match phases of contraction and expansion in migration, with high water marks following the expansion of the Silk Roads in the 5th century AD, the rise of maritime routes in the 11th century and a drastic restructuring of the trade network following the arrival of Europeans in the 16th century. The economic fluxes of the Indian Ocean trade network therefore directly shaped exchanges of genes, in addition to goods and concepts.


Subject(s)
Economics , Genetic Variation , Genetics, Population , Genomics , Population Dynamics , Human Migration , Humans , Indian Ocean , Models, Theoretical
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