Source populations Settlement of the Americas

1 source populations

1.1 human genomic models
1.2 htlv-1 genomics
1.3 physical anthropology
1.4 stemmed points

source populations

there general agreement among anthropologists source populations migration americas originated area somewhere east of yenisei river. common occurrence of mtdna haplogroups a, b, c, , d among eastern asian , native american populations has long been recognized, along presence of haplogroup x. whole, greatest frequency of 4 native american associated haplogroups occurs in altai-baikal region of southern siberia. subclades of c , d closer native american subclades occur among mongolian, amur, japanese, korean, , ainu populations.

human genomic models

the development of high-resolution genomic analysis has provided opportunities further define native american subclades , narrow range of asian subclades may parent or sister subclades. example, broad geographic range of haplogroup x has been interpreted allowing possibility of western eurasian, or european source population native americans, in solutrean hypothesis, or suggesting pre-last glacial maximum migration americas. analysis of ancient variant of haplogroup x among aboriginals of altai region indicates common ancestry european strain rather descent european strain. further division of x subclades has allowed identification of subhaplogroup x2a, regarded specific native americans. further definition of subclades related native american populations, requirements sampling asian populations find closely related subclades grow more specific. subhaplogroups d1 , d4h3 have been regarded native american specific based on absence among large sampling of populations regarded potential descendants of source populations, on wide area of asia. among 3764 samples, sakhalin - lower amur region represented 61 oroks. in study, subhaplogroup d1a has been identified among ulchis of lower amur river region(4 among 87 sampled, or 4.6%), along subhaplogroup c1a (1 among 87, or 1.1%). subhaplogroup c1a regarded close sister clade of native american subhaplogroup c1b. subhaplogroup d1a has been found among ancient jōmon skeletons hokkaido modern ainu regarded descendants of jōmon. occurrence of subhaplogroups d1a , c1a in lower amur region suggests source population region distinct altai-baikal source populations, sampling did not reveal 2 particular subclades. conclusions regarding subhaplogroup d1 indicating potential source populations in lower amur , hokkaido areas stand in contrast single-source migration model.

subhaplogroup d4h3 has been identified among han chinese. subhaplogroup d4h3 china not have same geographic implication subhaplotype d1a amur-hokkaido, implications source models more speculative. parent lineage, subhaplotype d4h, believed have emerged in east asia, rather siberia, around 20k cal years bp. subhaplogroup d4h2, sister clade of d4h3, has been found among jōmon skeletons hokkaido. d4h3 has coastal trace in americas.

the contrast between genetic profiles of hokkaido jōmon skeletons , modern ainu illustrates uncertainty in source models derived modern dna samples:

however, due small sample size or close consanguinity among members of site, frequencies of haplogroups in funadomari skeletons quite different modern populations, including hokkaido ainu, have been regarded direct descendant of hokkaido jomon people.

the descendants of source populations closest relationship genetic profile time when differentiation occurred not obvious. source population models can expected become more robust more results compiled, heritage of modern proxy candidates becomes better understood, , fossil dna in regions of interest found , considered.

htlv-1 genomics

the human t cell lymphotrophic virus 1 (htlv-1) virus transmitted through exchange of bodily fluids , mother child through breast milk. mother-to-child transmission mimics hereditary trait, although such transmission maternal carriers less 100%. htlv virus genome has been mapped, allowing identification of 4 major strains , analysis of antiquity through mutations. highest geographic concentrations of strain hltv-1 in sub-saharan africa , japan. in japan, occurs in highest concentration on kyushu. present among african descendants , native populations in caribbean region , south america. rare in central america , north america. distribution in americas has been regarded due importation slave trade.

the ainu have developed antibodies htlv-1, indicating endemicity ainu , antiquity in japan. subtype has been defined , identified among japanese (including ainu), , among caribbean , south american isolates. subtype b has been identified in japan , india. in 1995, native americans in coastal british columbia found have both subtypes , b. bone marrow specimens andean mummy 1500 years old reported have shown presence of subtype. finding ignited controversy, contention sample dna insufficiently complete conclusion , result reflected modern contamination. however, re-analysis indicated dna sequences consistent with, not from, cosmopolitan clade (subtype a). presence of subtypes , b in americas suggestive of native american source population related ainu ancestors, jōmon.

physical anthropology

paleoamerican skeletons in americas such kennewick man (washington state), hoya negro skeleton (yucatán), luzia woman , other skulls lagoa santa site (brazil), buhl woman (idaho), peñon woman iii, 2 skulls tlapacoya site (mexico city), , 33 skulls baja california have exhibited craniofacial traits distinct modern native americans, leading physical anthropologists opinion paleoamericans of australoid rather siberian origin. basic measured distinguishing trait dolichocephaly of skull. modern isolates such pericúes of baja california , fuegians of tierra del fuego exhibit same morphological trait. other anthropologists advocate alternative hypothesis evolution of original beringian phenotype gave rise distinct morphology similar in known paleoamerican skulls, followed later convergence towards modern native american phenotype. resolution of issue awaits identification of beringian phenotype among paleoamerican skulls or evidence of genetic clustering among examples of australoid phenotype.

a report published in american journal of physical anthropology in january 2015 reviewed craniofacial variation focussing on differences between , late native americans , explanations these based on either skull morphology or molecular genetics. arguments based on molecular genetics have in main, according authors, accepted single migration asia probable pause in berengia, plus later bi-directional gene flow. studies focussing on craniofacial morphology have argued paleoamerican remains have been described closer african , australo-melanesians populations modern series of native americans , suggesting 2 entries americas, 1 occurring before distinctive east asian morphology developed (referred in paper 2 components model . third model, recurrent gene flow [rgf] model, attempts reconcile two, arguing circumarctic gene flow after initial migration account morphological changes. re-evaluates original report on hoya negro skeleton supported rgf model, authors disagreed original conclusion suggested skull shape did not match of modern native americans, arguing skull falls subregion of morphospace occupied both paleoamericans , modern native americans.

stemmed points

stemmed points lithic technology distinct beringian , clovis types. have distribution ranging coastal east asia pacific coast of south america. emergence of stemmed points has been traced korea during upper paleolithic. origin , distribution of stemmed points have been interpreted cultural marker related source population coastal east asia.