Migration routes Settlement of the Americas

1 migration routes

1.1 interior route
1.2 pacific coastal route

1.2.1 east asians: paleoindians of coast
1.2.2 problems evaluating coastal migration models

migration routes
interior route

map showing approximate location of ice-free corridor , specific paleoindian sites (clovis theory).

historically, theories migration americas have centered on migration beringia through interior of north america. discovery of artifacts in association pleistocene faunal remains near clovis, new mexico in 1930s required extension of timeframe settlement of north america period during glaciers still extensive. led hypothesis of migration route between laurentide , cordilleran ice sheets explain settlement. clovis site host lithic technology characterized spear points indentation, or flute, point attached shaft. lithic complex characterized clovis point technology subsequently identified on of north america , in south america. association of clovis complex technology late pleistocene faunal remains led theory marked arrival of big game hunters migrated out of beringia dispersed throughout americas, otherwise known clovis first theory.

recent radiocarbon dating of clovis sites has yielded ages of 11.1k 10.7k c years bp (13k 12.6k cal years bp), later dates derived older techniques. re-evaluation of earlier radiocarbon dates led conclusion no fewer 11 of 22 clovis sites radiocarbon dates problematic , should disregarded, including type site in clovis, new mexico. numerical dating of clovis sites has allowed comparison of clovis dates dates of other archaeosites throughout americas, , of opening of ice-free corridor. both lead significant challenges clovis first theory. monte verde site of southern chile has been dated @ 14.8k cal years bp. paisley cave site in eastern oregon yielded c date of 12.4k years (14.5k cal years) bp, on coprolite human dna , c dates of 11.3k-11k (13.2k-12.9k cal years) bp on horizons containing western stemmed points. artifact horizons non-clovis lithic assemblages , pre-clovis ages occur in eastern north america, although maximum ages tend poorly constrained.

geological findings on timing of ice-free corridor challenge notion clovis , pre-clovis human occupation of americas result of migration through route following last glacial maximum. pre-lgm closing of corridor may approach 30k cal years bp , estimates of ice retreat corridor in range of 12 13k cal years bp. viability of corridor human migration route has been estimated @ 11.5k cal years bp, later ages of clovis , pre-clovis sites. dated clovis archaeosites suggest south-to-north spread of clovis culture.

pre-last glacial maximum migration interior has been proposed explain pre-clovis ages archaeosites in americas, although pre-clovis sites such meadowcroft rock shelter, monte verde, , paisley cave have not yielded confirmed pre-lgm ages.

the interior route consistent spread of na dene language group , subhaplogroup x2a americas after earliest paleoamerican migration.

pacific coastal route

possible migration routes americas predicted distribution of y-dna haplogroups: inland route (purple lines), pacific coastal route (brown dashed line), , possible trans-atlantic route (light blue double line).

pacific models propose people first reached americas via water travel, following coastlines northeast asia americas. coastlines unusually productive environments because provide humans access diverse array of plants , animals both terrestrial , marine ecosystems. while not exclusive of land-based migrations, pacific coastal migration theory helps explain how colonists reached areas extremely distant bering strait region, including sites such monte verde in southern chile , taima-taima in western venezuela. 2 cultural components discovered @ monte verde near pacific coast of chile. youngest layer radiocarbon dated @ 12,500 radiocarbon years (~14,000 cal bp) , has produced remains of several types of seaweeds collected coastal habitats. older , more controversial component may date far 33,000 years, few scholars accept component.

as chronology of deglaciation in interior , coastal regions of north america became better understood, coastal migration hypothesis advanced knute fladmark alternative ice-free corridor hypothesis. debate on coastal versus interior migration initial settlement has centered on evidence chronology of initial settlement of beringia, interior north america, pacific coast of americas, , timing of opening of coastal versus interior migration routes indicated geological evidence. complicating debate has been absence of archaeological data coastal , interior migration routes periods when initial migration proposed have occurred. recent variation of coastal migration hypothesis marine migration hypothesis, proposes migrants boats settled in coastal refugia during deglaciation of coast. proposed use of boats adds measure of flexibility chronology of coastal migration, continuous ice-free coast (16k-15k cal years bp) no longer required. coastal east asian source population integral marine migration hypothesis.

in 2014, autosomal dna of toddler montana, dated @ 10.7k c years (12.5-12.7 cal years) bp sequenced. dna taken skeleton referred anzick-1, found in close association several clovis artifacts. analysis yielded identification of mtdna belonging subhaplogroup d4h3a, rare subclade of d4h3 occurring along west coast of americas, geneflow related siberian mal ta population. data indicate anzick-1 population directly ancestral present south american , central american native american populations. anzick-1 less closely related present north american native american populations. d4h3a has been identified clade associated coastal migration.

the problems associated finding archaeological evidence migration during period of lowered sea level known. sites related first migration submerged, location of such sites obscured. types of evidence dependent on organic material, such radiocarbon dating, may destroyed submergence. wave action can destroy site structures , scatter artifacts along prograding shoreline. additionally, pacific coastal conditions tend unstable due steep unstable terrain, earthquakes, tsunamis, , volcanoes. strategies finding earliest migration sites include identifying potential sites on submerged paleoshorelines, seeking sites in areas uplifted either tectonics or isostatic rebound, , looking riverine sites in areas may have attracted coastal migrants. otherwise, coastal archaeology dependent on secondary evidence related lifestyles , technologies of maritime peoples sites similar associated original migration.

other coastal models, dealing peopling of pacific northwest , california coasts, have been advocated archaeologists knut fladmark, roy carlson, james dixon, jon erlandson, ruth gruhn, , daryl fedje. in 2007 article in journal of island , coastal archaeology, erlandson , colleagues proposed corollary coastal migration theory—the kelp highway hypothesis —arguing productive kelp forests supporting similar suites of plants , animals have existed near end of pleistocene around of pacific rim japan beringia, pacific northwest, , california, andean coast of south america. once coastlines of alaska , british columbia had deglaciated 16,000 years ago, these kelp forest (along estuarine, mangrove, , coral reef) habitats have provided ecologically similar migration corridor, entirely @ sea level, , unobstructed.

a 2016 dna analysis of plants , animals suggest coastal route feasible.

east asians: paleoindians of coast

the boat-builders southeast asia (austronesian peoples) may have been 1 of earliest groups reach shores of north america. 1 theory suggests people in boats followed coastline kurile islands alaska down coasts of north , south america far chile. 62 54, 57. haida nation on queen charlotte islands off coast of british columbia may have originated these asian mariners between 25,000 , 12,000 years ago. watercraft migration explain habitation of coastal sites in south america such pikimachay cave in peru 20,000 years ago (disputed) , monte verde in chile 13,000 years ago [6 30; 8 383].

there boat use in japan 20,000 years ago, says jon erlandson, university of oregon anthropologist. kurile islands (north of japan) stepping stones beringia, continuous land bridging bering strait. migrants, said, have skirted tidewater glaciers in canada right on down coast. [7 64]

problems evaluating coastal migration models

the coastal migration models provide different perspective on migration new world, not without own problems. 1 of biggest problems global sea levels have risen on 120 metres (390 ft) since end of last glacial period, , has submerged ancient coastlines maritime people have followed americas. finding sites associated coastal migrations extremely difficult—and systematic excavation of sites found in deeper waters challenging , expensive. on other hand, there evidence of marine technologies found in hills of channel islands of california, circa 10,000 bce. if there pre-clovis coastal migration, there possibility of failed colonization . problem arises lack of hard evidence found long chronology theory. no sites have yet produced consistent chronology older 12,500 radiocarbon years (~14,500 calendar years), research has been limited in south america related possibility of coastal migrations.