The Late Pleistocene Colonization of North America
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quaternary Review Setting the Stage: The Late Pleistocene Colonization of North America Michael J. O’Brien Department of Arts and Humanities, Texas A&M University—San Antonio, San Antonio, TX 78224, USA; [email protected] Academic Editors: Bronwen Whitney, Encarni Montoya and Valentí Rull Received: 25 August 2018; Accepted: 26 November 2018; Published: 21 December 2018 Abstract: The timing of human entrance into North America has been a topic of debate that dates back to the late 19th century. Central to the modern discussion is not whether late Pleistocene-age populations were present on the continent, but the timing of their arrival. Key to the debate is the age of tools—bone rods, large prismatic stone blades, and bifacially chipped and fluted stone weapon tips—often found associated with the remains of late Pleistocene fauna. For decades, it was assumed that this techno-complex—termed “Clovis”—was left by the first humans in North America, who, by 11,000–12,000 years ago, made their way eastward across the Bering Land Bridge, or Beringia, and then turned south through a corridor that ran between the Cordilleran and Laurentide ice sheets, which blanketed the northern half of the continent. That scenario has been challenged by more-recent archaeological and archaeogenetic data that suggest populations entered North America as much as 15,300–14,300 years ago and moved south along the Pacific Coast and/or through the ice-free corridor, which apparently was open several thousand years earlier than initially thought. Evidence indicates that Clovis might date as early as 13,400 years ago, which means that it was not the first technology in North America. Given the lack of fluted projectile points in the Old World, it appears certain that the Clovis techno-complex, or at least major components of it, emerged in the New World. Keywords: Clovis; drift; Folsom; late Pleistocene; learning; selection; transmission 1. Introduction The exact timing of the colonization of North America is open to question (see below), but what is not in question is the point of origin of the early colonists. Despite a few claims to the contrary, including one that envisions the colonization of North America by Upper Paleolithic people from western Europe some 20,000–24,000 years ago [1], overwhelming archaeological and archaeogenetic evidence [2–16] indicates that humans moved eastward across the Bering Land Bridge, or Beringia, during the Late Glacial Maximum and made their way either south along or near the coast [17–20] and/or through a corridor that ran between the Cordilleran and Laurentide ice sheets that covered the northern half of the continent [21–25]. Both scenarios remain equally viable [24], despite claims to the contrary [17]. With respect to timing, colonizing populations could have entered North America before 16,000 years ago, but the earliest unequivocal and widespread human occupation of the continent dates to around 13,400 years ago [25], the visible manifestation of which is a tool kit referred to as the “Clovis techno-complex” [26]. The dispersal of that techno-complex is exceptional in human-migration research because it occurred over such a short time (see below), which means that, as researchers, we benefit from a temporal resolution not usually available for other instances of colonization [27]. The dispersal of Clovis also allows us to examine at a fine scale how colonization processes can play out across a vast extent of space that at the time had at best a very small resident population. To set the stage for the other papers in this special issue of Quaternary, I focus on the origin and spread of that Quaternary 2019, 2, 1; doi:10.3390/quat2010001 www.mdpi.com/journal/quaternary Quaternary 2018, 2, x 2 of 22 Quaternary 2019, 2, 1 2 of 22 across a vast extent of space that at the time had at best a very small resident population. To set the stage for the other papers in this special issue of Quaternary, I focus on the origin and spread of that complex, togethertogether with with the the various various modes modes involved involved in in its its transmission. transmission. Along Along the the way, way, I examine I examine how varioushow various evolutionary evolutionary processes processes and mechanisms and mechanisms helped shape helped what shape we see what in the we Clovis see archaeologicalin the Clovis record.archaeological Excellent record. summaries Excellent of Clovis summaries lifeways of and Clovis numerous lifeways related and topics numerous not included related heretopics can not be foundincluded in [here28–35 can]. be found in [28–35]. 2. The Clovis Techno Techno-Complex‐Complex The Clovis techno-complextechno‐complex is marked by a number of distinctive tool types, including bone and ivory rods [[36],36], large prismatic stone blades [[26],26], and bifacially chipped and flutedfluted stone weapon tips, referred to as “Clovis points” [26,37–40]. [26,37–40]. Because of significant significant regional regional variation in in the the toolkit, toolkit, Eren and Buchanan [[41],41], (p. 1) make the excellent point that what archaeologists refer to as “Clovis technology” is better thought of as a shorthand reference to “a fuzzy set of human–tool interactions found across North and Central America during thethe terminalterminal Pleistocene”.Pleistocene.” Prehistoric projectile-weaponprojectile‐weapon systems were made from a variety of raw materials,materials, including wood, resins, bone, and fibers,fibers, but these materials do not preserve well, and as a result, result, archaeologists archaeologists focus on the component that does survive, the flaked-stoneflaked‐stone projectile point [[42].42]. Clovis points were made from several cryptocrystalline stone types, such as chert, quartzite, and obsidian.obsidian. They were bifacially flakedflaked (flaked (flaked on on both both sides) sides) and and are are lanceolate lanceolate in form. in form. They They have parallelhave parallel to slightly to slightly convex sidesconvex and sides concave and concave bases and bases exhibit and exhibit a series a ofseries flake-removal of flake‐removal scars—“flutes”—on scars—“flutes”—on one or one both or facesboth thatfaces extend that extend from thefrom base the tobase about to about a third a ofthird the of way the to way the to tip the (Figure tip (Figure1). After 1). flutedAfter fluted points points were firstwere recognized first recognized archaeologically, archaeologically, it was proposedit was proposed that fluting that enhanced fluting enhanced bloodletting bloodletting of a wounded of a animalwounded [43 animal], although [43], although the flute the would flute have would been have largely been largely covered covered by the by hafting the hafting (e.g., (e.g., sinew) sinew) [44]. Similarly,[44]. Similarly, it was proposedit was proposed that fluting that enhanced fluting haftingenhanced a point hafting into aa split point shaft into [45 a]. Experimentationsplit shaft [45]. suggests,Experimentation however, suggests, that the however, thinner basethat the that thinner results base from that fluting results acts from as a fluting “shock acts absorber” as a “shock that increasesabsorber” point that increases robustness point and robustness the ability and to withstand the ability physical to withstand stress physical through stress stress through redistribution stress andredistribution damage relocation and damage [46, 47relocation]. [46,47]. Figure 1. Clovis points from various North American sites. Photo by Charlotte D. Pevny; courtesy Michael R. Waters. Quaternary 2019, 2, 1 3 of 22 QuaternaryMicrowear 2018, analysis2, x shows that at least some Clovis points were used to tip spears that were3 of thrust22 and/or thrown [48]. Exceedingly large specimens could have functioned as saws, which were held in place byMicrowear bone or ivory analysis rods shows acting that as levers at least to some tighten Clovis sinew points lashings were [used49]. Theto tip basal spears edges that of were Clovis points,thrust where and/or they thrown were [48]. attached Exceedingly to socketed large foreshaftsspecimens could or lashed have to functioned handles or as spears,saws, which were were ground dull.held It has in place long by been bone presumed or ivory thatrods the acting grinding as levers was to done tighten to sinew prevent lashings cutting [49]. of the The lashings basal edges that of bind theClovis points points, in place where [40,45 they], but were recent attached experimental to socketed work foreshafts has shown or lashed that to there handles is virtually or spears, no were damage to lashings,ground dull. regardless It has long of whether been presumed a point that has the ground grinding or sharp was done edges to prevent [42]. cutting of the lashings thatThe bind antiquity the points of these in place iconic [40,45], points but was recent first documentedexperimental inwork the Americanhas shown Southwest that there is at virtually Blackwater no damage to lashings, regardless of whether a point has ground or sharp edges [42]. Draw, New Mexico [50,51], where they were found in association with the remains of extinct animals, The antiquity of these iconic points was first documented in the American Southwest at such as mammoths, camelids, sloths, and large bison, that were known to be Pleistocene in age. Blackwater Draw, New Mexico [50,51], where they were found in association with the remains of This discovery, alongside one made a few years earlier near Folsom, New Mexico [52], laid to rest a extinct animals, such as mammoths, camelids, sloths, and large bison, that were known to be long-standingPleistocene debatein age. This in archaeology discovery, alongside over the presence one made of a glacial-agefew years earlier humans near in Folsom, North AmericaNew Mexico [53, 54]. Since[52], those laid early to rest discoveries, a long‐standing Clovis debate points in have archaeology been found over throughout the presence the of contiguous glacial‐age humans United States, in Alaska,North southern America Canada, [53,54].