Characterizing the American Upper Paleolithic

Cactus Hill is a stratified dune site adjacent the Nottoway River on the coastal plain of southern Virginia (Fig. 1), e.g., (19) (see Supplementary Materials). Laminated sand layers at the site contain early Archaic, Clovis, and AUP deposits separated by 10 to 20 cm of culturally sterile sand (20). Chronology at the site suggests that the initial occupation of Cactus Hill was ~18,000 cal yr B.P. or earlier. While there are several dating issues, which contribute to uncertainty about this early age, the relative stratigraphic separation between the AUP and CPT horizons and the differences in technological characteristics between the lithic materials in the two horizons make it clear that the lowest cultural deposits date to some time before the CPT era.

Meadowcroft is a well-stratified rockshelter along a tributary of the Ohio River in western Pennsylvania containing an archeological record spanning the entire precontact period (Fig. 1) (see Supplementary Materials). The chronology for 11 stratigraphic units is controlled by more than 50 radiocarbon dates. These are in the correct stratigraphic order and are associated with diagnostic artifacts of the appropriate periods. The earliest AUP occupations are found in lower Stratum IIa, which dates to “…sometime between 13,955 and 14,555 radiocarbon years ago” (21).

Gault is an open site located along a small spring-fed stream on the ecotone between the central Texas hill country of the Edwards Plateau and the Blackland Prairie on the adjacent coastal plains (Fig. 1), e.g., (25) (See Supplementary Materials). More than 150,000 AUP artifacts, termed the “Gault Assemblage,” were recovered from the lowest two stratigraphic units (units 1 and 2) above bedrock in Area 15 of the site. These were separated from a similar number of CPT artifacts in unit 4 by a 10- to 15-cm-thick zone of markedly reduced lithic debris. The age range for units 1 and 2 is between ~21,700 and ~16,700 cal yr B.P. (25).

The Debra L. Friedkin site, located ~500 meters downstream from Gault (Fig. 1), also preserves AUP components stratified below Clovis. Excavations at Friedkin uncovered a pre-Clovis archeological component known as the Buttermilk Creek Complex (28, 29). During the initial fieldwork phase (2006 to 2009), 15,573 artifacts were recovered from a 20-cm-thick deposit beneath the Clovis horizon, including 83 tools and 15,490 pieces of debitage. This assemblage includes evidence of biface manufacture, blade and bladelet production, and core reduction strategies. A second excavation phase conducted in 2015 to 2016 expanded the assemblage to approximately 100,000 artifacts, including 328 tools and 12 complete and fragmentary lanceolate and stemmed projectile points (Fig. 4B) found 15 to 20 cm below the Clovis/Folsom zone (30). Among the tools confirmed from the ~15,500- to 13,500-year-old sediments are 40 late-stage biface fragments, as well as blade segments, bladelets, scrapers, a discoidal core, and snap fracture tools (radial and bend-break types), most commonly made on flakes but also on bifaces and retouched flakes. Artifact analysis is ongoing, and a full description of the 328 tools in the Buttermilk Creek Complex is forthcoming.

The Cooper’s Ferry/Nipéhe site is located along the lower Salmon River in west-central Idaho (Fig. 1), e.g., (31) (see Supplementary Materials). Geoarcheological study of two excavation areas at the site defined a stratified sequence of deposits, including a lower loess deposit lithostratigraphic unit 3/lithostratigraphic unit B3 (LU3/LUB3) that contains an AUP occupation with age controls provided by 18 ¹⁴C age estimates. Bayesian modeling of radiocarbon data places the start of occupation to between ~16,045 and ~15,725 cal yr B.P. Lithic debitage and stemmed projectile points recovered in situ outside and stratigraphically below dated pit features indicate an older as yet undated human occupation.

There are several other North American sites with lithic assemblages of the appropriate age, which have technological characteristics similar to those summarized here. Several of these have rather large stone tool assemblages, but issues with chronology and stratigraphic placement, make these assemblages difficult to assess. We consider only four complementary sites where we feel that chronological and stratigraphic controls are sufficient to allow comparison to the larger assemblages described above.

The Page-Ladson site is contained in a sinkhole along the Aucilla River in the Florida panhandle (Fig. 1), e.g., (37) (see Supplementary Materials). Comprehensive dating of the depositional sequence produced 71 ¹⁴C age estimates on wood preserved in the submerged deposits, with 24 of these coming from a stratigraphic column bracketing lithic materials. Seven, with an average age of ~14,550 cal yr B.P., are directly related to a biface and other flake tools (37). The site’s AUP lithic assemblage recovered during the two excavation phases is limited to a broken biface, two flakes showing evidence of use, and an additional 11 pieces of debitage (37, 38). The flakes are described as bifacial thinning flakes, and the pointed biface is interpreted as functioning as a knife. One of the bifacial thinning flakes has a ground platform and is more than twice as long as it is wide. This blade flake may be derived from the initial forming of a blade core but by itself is insufficient to demonstrate that a core-and-blade technology was present at the site. Together, the pieces of debitage suggest that they were produced from the resharpening of at least three different tools (38).

Schaefer and the nearby Hebior site are two mammoth (Mammuthus primigenius) butchering sites in southeastern Wisconsin located on the margin of what was the fluctuating Laurentide Ice Sheet at the time the bones were deposited (Fig. 1), e.g., (39, 40) (see Supplementary Materials). The age of the Schaefer mammoth, which appears to have been butchered (41), is controlled by 13 ¹⁴C dates directly on mammoth bone and another 17 on wood macrofossils recovered from the peat in and around the bones (40), which average about 14,750 cal yr B.P.

While the lithic assemblage at Schaefer is limited to the two recovered blade flakes, they are diagnostic in that they represent the production of blade flakes for use as a principal tool type by AUP foragers. Both flakes are made from local chert. One of them is a prismatic blade, termed a “crest blade” by Joyce (40). This lame à crête would probably indicate use of a blade core technique to produce these blades. The Hebior mammoth was associated with two chert bifaces, a chert flake, and a flaked chopper made on dolomite (39, 42, 43).

The Paisley Caves are a set of small closely spaced caves overlooking Summer Lake in southeastern Oregon (Fig. 1), e.g., (44). Chronology is controlled by more than 400 ¹⁴C age estimates with more than 100 dating to earlier than ~12,800 cal yr B.P. Human fecal remains and stemmed points at the site date to before ~14,000 cal yr B.P., with the five earliest human coprolites dated to between ~12,500 and ~12,000 B.P. (~14,500 to ~14,000 cal yr B.P.) (45). Biface production was apparently the focus of the AUP knappers at Paisley Caves, although the number of formal tools is limited. Cutting tools consist only of a single biface and an edge-modified flake. The two older projectile points are broken but are both stem forms. The obsidian points were produced using bifacial collateral flaking, resulting in biconvex cross sections.

The stems on the two points are moderately long and tapered, ranging from ~25 to 40 mm from the base to slight shoulders where the blades begin. The distal ends of the stems are ~17 to 22 mm wide, with the stems tapering to slightly rounded bases of ~5 to 10 mm. The stem margins on the oldest point dating to between ~13,170 and ~13,314 cal yr B.P. are finely retouched and edge ground. The stem of the other possible AUP point is unground and has not been finely shaped by retouch. It may either have been broken during initial manufacture or was reworked and repurposed into a knife after it was broken. The shape and length of the blades are unknown.

There is no evidence of blade production in the Paisley Caves AUP lithic assemblage, but the number of tools in the collection is quite small, so the absence of blades may not be definitive. On the other hand, the amount of debitage is relatively large, and if blade production was common, then blade fragments might be expected to show up in the assemblage. Moreover, as Jenkins et al. (44) note, blades are extremely rare in later Western Stemmed Tradition (WST) assemblages, a Late Pleistocene to early Holocene cultural pattern defined by nonfluted stemmed and lanceolate projectile points found at many sites in western North America, e.g., (46–49). This WST pattern suggests that blades and formalized blade production may also have been absent at Paisley Caves.

A basic characteristic of AUP lithic technology is the production of linear flakes and blades from unidirectional, discoidal, polyhedral, and Levallois-like cores (Table 1). These flakes, blades, and spalls are used as informal tools and are further reduced to create a range of formal tools including bifaces, projectile points, gravers, unifaces, and burins. In some, but not all, AUP sites, projectile point production appears to be based, in part, on the relatively minimal reduction of flakes and blades, which often result in forms that tend toward plano-convex cross sections. Larger AUP biface technology is seen as well and appears to be based on more extensive reduction of larger flake spalls into bifacial preforms and finished bifaces with biconvex cross sections. AUP points are unfluted and appear in stemmed and lanceolate forms. AUP points are generally small, and examples from the Gault, Friedkin, and Cooper’s Ferry/Nipéhe sites are particularly diminutive—the smallest of which measured ~2 to 4 cm in length. AUP points appear in a range of two-dimensional hafting forms, including contracting rounded, pointed, and squared bases (Cooper’s Ferry/Nipéhe), concave and slightly contracting margins with squared bases (Meadowcroft), and expanding and slightly convex margins with square and concave bases (Gault). The stemmed AUP points generally have basal edge grinding, even including the smallest point form seen at the Cooper’s Ferry/Nipéhe site, which suggests that it was deployed in some kind of haft. Bifacial reduction is evident in the tools and debitage found at Cactus Hill, Meadowcroft, Gault, Friedkin, Cooper’s Ferry/Nipéhe, Hebior, Page-Ladson, and Paisley Caves. While bifacial collateral flaking to a midline is most common, overshot flakes were found in pre-Clovis contexts at Gault, Friedkin, and Cooper’s Ferry/Nipéhe. Further research is needed to determine whether this technological feature is unique to the CPT or has its origins in the AUP. The presence of smaller projectile points made on flakes or blades and larger bifaces made through more intensive reduction of bifacial preforms illustrates an important duality in AUP lithic technology that is reflected in later CPT and WST point forms where large and small point forms were used together. While the points were made through both bifacial reduction and modification of blade flakes, they can take the same general morphological shape. These shapes are varied in general, but small triangular forms are more common in eastern North America while stemmed forms are more common in the West. The AUP components at Cooper’s Ferry/Nipéhe also contain fragmentary prismatic blades made on cryptocrystalline silica and a unidirectional bladelet core made on fine grained volcanic material from PFA2 (34) and two fragments of prismatic blades made on chert.

As Adovasio et al. (23) concluded decades ago: “Collectively, these data suggest that the first inhabitants of eastern North America employed a technologically standardized and sophisticated, small, polyhedral core– and blade-based industry of decidedly Eurasiatic, Upper Paleolithic ‘flavor’.” With the excavation and reporting of several additional well-dated AUP sites, this Upper Paleolithic “flavor” has become even more evident, leading to the obvious question of where this technology may have originated. The antecedents of the AUP may have been either in Europe or Asia, as Adovasio et al. noted, and a European origin for this American lithic technology has been suggested by some, e.g., (50). However, paleogenetic studies indicate that an Asian origin for Ancient Native American (ANA) populations (51) and the progenitors of AUP technology were most probably located somewhere in northeastern Asia. Unfortunately, these paleogenetic data are not yet sufficient to tell us where that location might have been.

One possibility is Beringia, the land bridge that connected Asia to the Americas during the Late Pleistocene. That bridge has long been held to be the most logical land route used by migrating ancient North Asians, e.g., (52), and until several North and South American sites were shown to predate the opening of an ice-free corridor between Beringia and the Americas south of the ice sheets, that route was long considered to be the only viable one. The hypothesis was so embedded in peopling of the America models that most of the same paleogenetic studies, which pinpointed a Northeast Asian source for those early populations, also identified an isolated standstill during that migration as a “Beringian standstill” without a shred of evidence that it took place in Beringia, e.g., (53, 54). There are, however, good reasons to question that widely held assumption.

First, there are no known stone tool complexes in Beringia that are old enough and/or similar enough to be possible progenitors of AUP technology. All lithic tool assemblages in eastern Beringia postdate ~14,500 cal yr B.P., lack large core-and-blade production, and are characterized by a microblade technology and a small “teardrop-shaped” projectile point pattern that is not found in the AUP (17, 18, 55). Later lanceolate and stemmed point forms appear to have been introduced to eastern Beringia from lower-latitude North America (56). Second, what is known of Beringian paleogenetics suggests that Late Pleistocene populations there dating to ~11,500 cal yr B.P. did not contribute to the populations that first occupied North America south of the ice sheets (57). Similarly, paleogenetics suggest that pre–Last Glacial Maximum (LGM) populations in far northeastern Siberia did not contribute to ANA populations and that those early populations were replaced later by different groups from East Asia (58), in keeping with archeological evidence that northern Siberia was largely abandoned by humans during the LGM (17, 59). In other words, present speculation that ANA populations and AUP technology originated in Beringia, e.g., (7, 8), is just that—speculation—and so we need to look elsewhere for a likely cultural progenitor of the AUP. The archeological record of the northwestern Pacific Rim’s Paleo-Sakhalin-Hokkaido-Kuril (PSHK) peninsula and its vicinities in continental East Asia is older than the AUP, is geographically most proximal to North America, and is therefore the more likely region where an AUP cultural progenitor may be found. That too is largely speculation, given that there is much we still do not know about the Paleolithic technologies around the PSHK region, with part of that problem likely due to limited English language publications. Intensive study of collections will be needed to support a meaningful comparison between LUP lithic assemblages in both northeastern Siberia and the PSHK regions and AUP lithic technologies.

Davis et al. (31, 36), Davis and Madsen (5), and Buvit et al. (60) suggest that the pre-Clovis–aged large and small stemmed projectile point, core-and-blade, and biface technology found at AUP sites such as in the LU3/LUB3 deposits at Cooper’s Ferry/Nipéhe share design and manufacturing links with Late Pleistocene–aged lithic technological traditions observed in the PSHK region (Figs. 1, 6, and 7). Paleogenetic studies indicate that the progenitors of the First Americans share genetic ancestry with LUP peoples from both southern Siberia and far eastern Asia, becoming geographically isolated sometime after ~25,000 cal yr B.P. (57, 61, 62) before expanding into the Americas after ~19,500 cal yr B.P. (62, 63). While paleogenetics has not yet pinpointed the exact location of their northeastern Asian residence, archeological evidence—particularly lithic technology—provides critical clues. The closest comparable projectile point forms in Northeast Asia to those predating ~16,000 cal yr B.P. found at the AUP sites discussed here are associated with LUP bifacial point-bearing sites in Hokkaido, (Fig. 6), e.g., (31, 36, 60).

The Okushirataki 1 site was excavated during rescue campaigns conducted by the Hokkaido Archaeological Operations Center in 1997 and 2000. This site is important, as it provides a basis for establishing the age of LUP bifacial stemmed points in the PSHK region. A large excavation block covering 7752 m² revealed 53 lithic scatters and 19 dense charcoal concentrations, primarily within an eolian sediment deposit designated as lithological unit IIa. In total, 830,243 lithic artifacts were unearthed, with 99,249 items found and mapped in situ. The site contains evidence of repeated occupation, beginning with an Early Upper Paleolithic (EUP) component characterized by a small flake-based tool assemblage. This was later followed by microblade technologies and bifacial points associated with subsequent LUP occupations (64–66).

Lithic scatter no. 53 at Okushirataki 1 yielded key evidence regarding bifacial stemmed points. A total of 9915 stone artifacts was recovered. Associated charcoal from feature no. 19 provided three radiocarbon dates with mean calibrated ages of ~21,400, ~21,360, and ~19,830 cal yr B.P. The youngest of these, ~19,830 cal yr B.P., is interpreted as the approximate age of the lithic assemblage. The elimination of older dates, combined with the occurrence of similar dates at other locations within the site, may suggest a past wildfire event. The lithic assemblage from this scatter includes bifacial projectile points, four of which being stemmed forms, as well as bifacial blanks or preforms, burins, end scrapers, side scrapers, and boat-shaped tools (Fig. 7). Other artifacts found at the site include retouched blades and flakes, prismatic blades, elongated flakes, blade cores, other cores, spalls, and a large quantity of debitage. Additional items such as anvil stones and a single obsidian nodule were also recovered. Obsidian dominates the lithic raw material assemblage, with minor occurrences of other cryptocrystalline rocks such as siliceous shale and agate. Chronological analysis of flake scar patterns, along with an extensive refitting analysis, indicates that the lithic artifacts in scatter no. 53 were primarily produced through blade-based, flake-based, and bifacial reduction techniques. The bifacial stemmed points, as shown in Fig. 7, were manufactured from the reduction of larger elongated flake blanks.

The Hattoridai 2 site was excavated during 3 years of excavations conducted by the Hokkaido Center for Buried Cultural Property between 1998 and 2000 (64). The excavation covered a vast area of 6691 m² on a very flat terrace along the Yubetsu River. A total of 65 lithic scatters and nine dense charcoal concentrations were found, primarily within eolian sediments of lithological unit IIa. In total, 798,648 lithic artifacts were unearthed, with 67,754 mapped in situ. The site contains an archeological sequence that begins with an EUP component, followed by an LUP component, which is characterized by various types of microblade technologies, and bifacial projectile points.

Lithic scatter no. 39 at Hattoridai 2 contains 3721 stone artifacts. Among these, 22 are bifacial projectile points, including 6 stemmed examples, along with 44 bifacial blanks or preforms, 3 end scrapers, 5 side scrapers, 6 retouched blades and flakes, 27 blades, 7 elongated flakes, 13 cores, 3 spalls, and 3594 flakes. Obsidian is the dominant raw material, with smaller amounts of siliceous shale, glassy andesite, and jasper. The artifacts were primarily produced through blade-based, flake-based, and bifacial reduction techniques. Charcoal from feature no. 5, which was a combustion feature directly associated with this lithic concentration, yielded three radiocarbon dates, with mean calibrated ages of ~16,750, ~16,620, and ~16,170 cal yr B.P. (64).

For the purpose of comparing AUP and eastern Beringian lithic technologies, the artifact assemblages from lithic scatter 53 at Okushirataki 1 and lithic scatter 39 at Hattoridai 2 lack microblade and microcore technologies, distinguishing them from other LUP toolkits in the region. However, the relative chronology and uses of microblades versus bifacial stemmed points in Hokkaido are complex and have been major research topics among local archeologists for a long time. Several assemblages contain both microblade reduction technology and bifacial stemmed points, although not always. For example, Hirosato- and Oshorokko-type microblade cores are found alongside Tachikawa-type bifacial stemmed points at sites such as Yoshizawa, Motomachi-2, and Nakamoto, while other bifacial point assemblages, such as those at Ochiai and Satsunai N sites, lack microblade reduction (67, 68). The reasons for this variation remain unclear. Some researchers attribute it to temporal changes, while others suggest functional and contemporaneous differences between sites, but both interpretations lack solid evidence.

Microblade technology appeared in PSHK around the onset of the LGM and began to spread in southern Siberia ~23,000 cal yr B.P. (59, 60, 69). It continued to spread across Siberia, particularly in regions where these novel inset weapons served, in part, as a solution to the challenges of provisioning during long, harsh winters—supporting tactics adapted to the risks of cold-weather large-game hunting (70). Nonetheless, microblade technology is also found in later periods, for example, as far south as southern Kyushu, Japan, in the LUP context (71). It has even been controversially argued to be in association with pottery by 15,000 cal yr B.P. (72). Therefore, the appearance, design, and functional purposes of microblade technology in relation to environmental conditions may require further assessments. In eastern Beringia, microblade technology first appears after 14,500 cal yr B.P., followed by the emergence of smaller, thinner, teardrop-shaped bifacial projectile points shortly after 14,000 cal yr B.P. (17). Microblade technology, despite its utility in Siberia and Beringia, was not transmitted into AUP sites south of eastern Beringia during the Late Pleistocene for reasons yet to be fully explained.

The appearance of fully bifacially flaked, stemmed projectile points in the PSHK region after ~20,000 cal yr B.P. marks a critical innovation in ranged weapon systems. This innovation introduced the bifacially flaked elliptical cross-sectional ogive projectile (ECOP) design (Fig. 8), characterized by blade margins that converge to a pointed tip, forming a two-dimensional ogive shape with intersecting convex curves. While the ogive form is an outline shape that is commonly used in modern cylindrical bullets and missile nose cones, bifacial projectile points differ in their flattened elliptical bifacial cross section, which enhances strength and durability (73) and resharpening potential. Earlier linear blade points, lacking an elliptical bifacial cross section, were likely less robust and less as effective as a durable, maintainable ballistic weapon as these later bifacially flaked ECOP designs. The design and manufacturing processes of bifacial projectile points, therefore, are critical to the argument for a cultural connection between the AUP and the LUP of the PSHK region.

Before ~19,830 cal yr B.P., extensively bifacially flaked, stemmed projectile points were absent in Asia. Instead, sites in the mainland dating to this period demonstrate the use of composite microblade projectile technology, e.g., (74–76), as well as projectile points made on linear blades with minor pressure flaking to sharpen the tips and create hafting elements (74). The absence of bifacially flaked ECOP technology in mainland Asia before ~19,830 cal yr B.P. and in Beringia before ~14,000 cal yr B.P. suggests that this region was not the source of AUP projectile point technologies. Instead, the ECOP forms originating in the PSHK region provide the most direct technological link between Late Pleistocene Northeast Asia and North America. While Late Pleistocene populations in the PSHK region may have been familiar with both microblade and bifacial projectile point technologies around the LGM, if they were the source population, only bifacial ECOPs, prismatic blades, and bifacial tools were brought into North America south of the continental ice sheets after ~20,000 cal yr B.P.

Potter et al. (8) argue that stemmed projectile points cannot be used as a diagnostic cultural marker to link Late Pleistocene populations in North America and the PSHK region, stating that “stemming is a widespread form of haft design innovated numerous times across multiple continents and is thus not an appropriate derived character on which to base a hypothesis of cultural affiliation.” However, in focusing on haft design, Potter et al. (8) seem to be missing the point. While we agree that relying solely on haft design as a taxonomic attribute is problematic, their critique overlooks the broader significance of bifacially flaked ECOP blade technology as a diagnostic technological characteristic and transformative innovation. The invention and transmission of ECOPs fundamentally reshaped projectile weapon systems and likely played a critical role in enabling human migration into the Americas during the Late Pleistocene. One explanation for the continued adoption of the ECOP design in the Americas is that the development of ECOP technology during the LGM in PSHK may have been a key departure from earlier lithic traditions, such as microblade-based composite projectile systems that dominated human migrations to Siberia and later into Beringia. Unlike earlier technologies in PSHK and Siberia, which relied on composite systems of microblades combined with organic components, ECOPs introduced a bifacial blade form with an elliptical cross section. We hypothesize that this innovation enhanced strength, durability, and the ability to resharpen, improving overall weapon performance and marking a fundamental shift in lithic manufacturing strategies. Crucially, it was ECOP technology—not microblade technology—that was carried into North America by populations moving south of the continental ice sheets. The appearance of fluted points—another form of ECOP—in eastern Beringia postdates the emergence of the CPT in mid-latitude North America and seems to have spread northward through the ice-free corridor after ~12,700 cal yr B.P. (77, 78). Although the reasons for the delayed decision in adopting the ECOP design weapons by foragers in eastern Beringia requires investigation, evidence underscores the fact that Late Pleistocene ECOPs did not originate in Beringia. ECOPs are present in pre-Clovis AUP sites south of the ice sheets well before their appearance in Beringia, underscoring their foundational role in the technological toolkit of the earliest populations in the Americas. As a key innovation, ECOPs provide an evolutionary link connecting Paleoindian developments, earlier AUP practitioners, and their origins in PSHK. Emerging during the LGM in PSHK, ECOPs mark an important advancement in lithic technology, bridging the technological lineage from the LUP of PSHK to the AUP and, ultimately, to the Paleoindians. By focusing on ECOP technology rather than the various forms of stemmed hafting, we can identify a meaningful connection between PSHK and AUP populations. The temporal and geographic pattern is clear: The ECOP design originated in or near PSHK during the LGM and spread southward into mid-latitude North America with early human migrants, before appearing in Beringia, and ultimately served as the cornerstone for the development of later Paleoindian lithic traditions.

While these technological similarities suggest a possible cultural connection between LUP manifestations in the PSHK and the AUP, the nature of paleogenetic connections are largely unknown. There is some evidence that Jomon populations did not contribute to AUP populations (79, 80), suggesting a non-Japan origin. Jomon cultural manifestations (e.g., pottery) appeared in the Japanese archipelago south of Hokkaido as late as ~15,500 cal yr B.P. (72, 81, 82) but possibly as early as ~17,000 cal yr B.P. (83). The Jomon cultural pattern is recognized on Hokkaido at only two sites. One is the Taisho 3 site, where dates on charcoal residue on pottery range from ~14,700 to ~13,900 cal yr B.P. (the actual age of these sherds may be somewhat later due to an unknown marine reservoir effect) (68, 72, 84). The other is the Tachikarushunai M-I site, dating to ~15,100 to ~13,800 cal yr B.P., e.g., (83). In addition, technical analyses of the lithic assemblages from non–pottery-bearing Incipient Jomon sites in Hokkaido (e.g., at the Kyushirataki 5 site) show that they are dominated by willow-leaf projectile points with denticulate edges (83). These bifacial points, and associated pressure flaking patterns, are distinct from contemporary Terminal Upper Paleolithic sites (85). Because the flaking patterns of the Hokkaido Jomon lithic assemblage are similar to the Jomon sites to the south, Natsuki (83) suggests that the Incipient Jomon left Hokkaido and moved to Honshu during cold conditions coinciding with the Younger Dryas (~13,000 to 11,500 cal yr B.P.). Later, the Initial Jomon reimmigrated to Hokkaido, where their society developed from a blend of the LUP traditions of Hokkaido and the Jomon culture of Honshu.

Recent genomic advances suggest that the Jomon people were direct descendants of LUP groups that migrated into the Japanese archipelago from Southeast Asia (86). Nonetheless, potential differences between the Jomon lineage and LUP populations of Hokkaido remain poorly understood. Notably, recent studies imply the LUP groups of PSHK were likely genetically distinct from the ancestral Jomon population of Honshu, e.g., (87), supporting the view that northern groups that developed microblade technology during the LUP were not descendants from the southern groups, e.g., (86). Given the AUP chronology discussed above, we suggest the parent LUP population in Northeast Asia dates to before ~20,000 cal yr B.P., and until human skeletal remains older than that age are found in the PSHK and nearby regions of Northeast Asia, it will remain impossible to use genetics alone to speculate on possible locations of antecedent AUP populations. However, genomic studies leave open the possibility of a “ghost population” existing in Hokkaido during the LUP. The distinctive technological features seen in Hokkaido LUP lithic assemblages dating to between ~20,000 and ~16,000 cal yr B.P. provide some of the strongest clues potentially linking the cultural patterns of the LUP in the PSHK to the AUP. While we cannot yet determine whether the LUP populations on Hokkaido or elsewhere in the PSHK (or Beringia, for that matter) were directly genetically related to the First Americans, their technological lithic traditions do suggest potential cultural connections. By focusing on these commonalities, it may be possible to more definitively identify whether the region served as a source of technological or cultural progenitors for the tools and technologies that later appeared in the Americas.

While the beginnings of the AUP remain unclear and will likely always remain so given the unlikelihood of finding the single earliest human occupation of the Americas, the end of the AUP is relatively well defined, both chronologically and in terms of the diagnostic tools, which mark the shift to the following Paleoindian period. About 13,000 cal yr B.P., across most of the Western Hemisphere, there was a marked shift to the use of large sturdy lanceolate points probably used to tip throwing or thrusting spears and javelins. Concurrently, the production and use of large core-and-blade implements ceased to be an important part of the lithic toolkit, although this shift was more rapid in some places than in others.

In western North America, Bayesian modeling of associated ¹⁴C age estimates suggests that the use of large lanceolate Haskett-type stemmed projectile points became widespread beginning sometime between ~13,260 and ~12,895 cal yr B.P. (3, 88). These stemmed points, with ECOP blade designs and stemmed hafts that are typically longer than the blade portion of the projectile, reached up to 226 mm in length and weighed as much as 61.8 g (89). Relatively large and robust stemmed points occur in the AUP levels at Cooper’s Ferry/Nipéhe, reaching 67 mm in length (a broken point may have been up to 10 cm in length) and weighing as much as 9.24 g, but the advent of the considerably larger Haskett variety stemmed points represents an elaboration of this form. As Duke and Stueber (89) note, Haskett and Clovis points are similar in terms of size, function, technological production techniques, required knapping skills, and the ways in which they are reworked or resharpened. Haskett and Clovis, according to Duke and Stueber (89), “…share a system of repair, long use life, and multipurpose functional trajectory that has some quantifiable measure of similarity.” While prismatic blade and Levallois-like cores persist into the early Holocene at a few sites such as Cooper’s Ferry/Nipéhe, for the most part core-and-blade technologies, one of the primary characteristics of AUP assemblages, disappear concurrently with the appearance of Haskett points. The number of WST sites with large lithic assemblages directly dated to ~13,000 cal yr B.P. is limited, but there are thousands of WST sites around many of the terminal Late Pleistocene to early Holocene-aged lakes in the Great Basin with surface assemblages dating to ~13,000 to 8500 cal yr B.P.; all of which lack core-and-blade components, e.g., (49).

In central and southeastern North America, similar large, robust Clovis lanceolate points appear at about the same time. Bayesian modeling of ¹⁴C age estimates associated with Clovis points suggest that they first appear sometime between ~13,275 and ~12,980 cal yr B.P. (3). This age range begins slightly later than a similar chronological modeling effort, which includes sites without direct evidence of Clovis diagnostics (2). In that regard, there are actually fewer radiocarbon age estimates directly associated with Clovis assemblage diagnostics than are associated with AUP assemblages. Unlike the WST sites to the west, Clovis assemblages retain some core-and-blade tool production strategies, but these are elaborated to include the use of large conical cores to produce elongate blade forms (90, 91). Even these blades forms were largely abandoned by the end of the very short ~600 to ~250-year Clovis period (3) when Clovis fluted point styles were elaborated into those found in later Folsom assemblages (90). What caused such a marked shift in projectile point forms and functions between the AUP and the following period of lanceolate point use is as yet unknown, although the nature and timing of that shift are clear. Because what is known about the (probable) varied nature of AUP subsistence and settlement systems is extremely limited, as indeed what is known about adaptations during the following lanceolate period, any hypotheses about what may have led to this technological shift would be largely speculative. We suspect that the shift may be related to the gradual extirpation of many Late Pleistocene mammal species during the Bølling-Allerød climatic period between ~14,700 and ~12,900 cal yr B.P. and to a marked reduction in the population of many other large-bodied species, such as mammoths, by the end of the following Younger Dryas, e.g., (92).