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A Terminal Pleistocene Child Cremation and Residential Structure from Eastern Beringia

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Science  25 Feb 2011:
Vol. 331, Issue 6020, pp. 1058-1062
DOI: 10.1126/science.1201581

Abstract

The dearth of human remains and residential sites has constrained inquiry into Beringian lifeways at the transition of the late Pleistocene–early Holocene. We report on human skeletal remains and a residential structure from central Alaska dated to ~11,500 calendar years ago. The remains are from a ~3-year-old child who was cremated in a pit within a semisubterranean house. The burial-cremation and house have exceptional integrity and preservation and exhibit similarities and differences to both Siberian Upper Paleolithic and North American Paleoindian features.

Evidence for the human colonization and early habitation of the Americas is primarily represented by stone tools and short-term camps and special task areas (e.g., workshops, kill sites) (1, 2). Residential structures and human burials from the American late Pleistocene and early Holocene are rare; none are known for the North American Subarctic and Arctic. Here, we describe the discovery of human and cultural remains within a semisubterranean structure at the Upward Sun River Site (USRS) in central Alaska (3). The human remains are those of a child who was cremated and buried, providing cultural information regarding early Beringians.

USRS is located on a loess-mantled sand dune near the northern scarp of a terrace above the active Tanana River floodplain (Fig. 1). Excavations indicate that ~260 cm of loess overlies >640 cm of aeolian sand (Fig. 2). Several thin paleosols (Ab horizons) 50 to 160 cm below the surface indicate brief breaks in loess sedimentation. There are four cultural components each separated by 20 to 90 cm of sterile sediment; the upper three (Components 2 to 4) are associated with these paleosols (Fig. 2). The stratigraphy of these paleosols indicates little to no cryoturbation or other mixing processes in the occupation layers, though there is evidence of limited cryoturbation in the upper B horizons (B through Bwb2), above the burial (4) (Fig. 2). Geoarchaeological details are provided in the supporting online material (fig. S1 and table S1). The burial and house are associated with Component 3, the third oldest at the site.

Fig. 1

Location of ancient North American human remains. (Inset) Upward Sun River Site map. Glacial limits for the earliest Beringian occupations (~14,100 cal yr B.P.) and time period of USRS occupation (~11,500 cal yr B.P.) are derived from (7). kya, thousand years ago.

Fig. 2

Stratigraphic profiles and radiocarbon date locations for Upward Sun River. (Inset) Stratigraphic profile locations on the excavation grid. For radiocarbon dates, s denotes split samples. Illustrated strata comprise the uppermost lithostratigraphic unit. IV, upper silt loess. See SOM Text for sediment and soil descriptions.

The burial and house were identified during a 2010 excavation designed to explore the earliest late Pleistocene component. The remains were within a pit-hearth east of our main excavation (Fig. 1). After consultation with government and Native representatives, we excavated the entire feature and connected it with the Main Block through an 8-m trench, for a contiguous excavated area of 42 m2 (Figs. 2 and 3).

Fig. 3

Plan view of house floor and burial. (Inset A) Spatial position of human remains. (Inset B) Stratigraphic profile of the house floor.

The burial pit–hearth (Feature 5, Figs. 2 and 3) is an oval depression ~45 cm deep, measuring 130 cm by 100 cm at the top and 80 cm by 60 cm at the bottom. It is well defined by a thick lens of charcoal and oxidized sediment 11 cm thick at the base and thinning on the sides. The pit edges flare out to form a flat, roughly circular surface 280 cm across, delineated by a thin (~5- to 10-mm thick) layer of charcoal and gray-stained loess. Lithic artifacts and faunal remains are localized within this stain and exhibit clear arcs of debris to indicate the presence of a house wall and floor. The cross-section of this larger feature shows that it was a semisubterranean feature dug about 27 cm below the contemporary ground surface (Fig. 2). Six apparent postmolds were observed as localized reddened stains, most with charcoal fragments and all with sharp edges in plan view and cross-section; four surround the pit-hearth. Overall minimum dimensions, arcs of debris among artifacts and fauna, and clear stratigraphic integrity of the feature support the interpretation of a semisubterranean house (fig. S2).

The pit-hearth consists of 15 to 37 cm of fill overlying a base composed of a 3-cm-thick oxidized layer with burned human and few faunal remains, a 1- to 3-cm-thick charcoal-rich layer, a 1-cm-thick ashy layer containing numerous burned fish and small-mammal bones, and a 3- to 4-cm-thick oxidized layer with abundant charcoal with some burned faunal remains. The human remains were above the fauna, indicating that the pit was not specifically created for the burial, which represents the last use of the feature.

The human remains were concentrated toward the west/central part of the pit (Fig. 3); they comprise many variably burned bones that, although fragmented (most <2 cm across), were still in their approximately original position. Charred wood fragments (some 15 cm long) were interspersed with the human and faunal remains throughout the oxidized layers of the pit, representing the fuel source(s) of the cremation and earlier burning episodes. Two of these larger fragments are Populus balsamifera (poplar). The spatial orientation of the human remains, artifacts, and contexts indicate that the pit was backfilled soon after interment, thus encapsulating the find and facilitating preservation.

Twenty 14C samples from within the pit and overlying and underlying strata provide a secure chronology for this feature, and all four components (table S2). Two charcoal samples from the base of the pit (Beta-280585, 280586) were contemporaneous with a date on the top of the pit fill (Beta-280584); all three average 9990 ± 30 years before the present (yr B.P.) [11,620 to 11,280 calendar (cal) yr B.P.] (5). Two outdoor hearths are located in the same stratigraphic layer (~14 to 17 cm below Ab3) in the Main Block several meters to the west (Fig. 1); these yield similar ages. Three additional 14C samples from strata above the burial pit provide upper limiting ages, including two contemporaneous dates on Ab3 (Paleosol 2) averaging 8870 ± 30 yr B.P. (10,170 to 9790 cal yr B.P.). In sum, the 14C dating and stratigraphy support secure contexts for the pit and human remains. They are estimated at ~11,500 cal yr B.P., at the end of the Younger Dryas chronozone, after the opening of the Ice Free Corridor and during a period when a land connection between northeast Asia and Alaska was still present or had only recently been inundated (6, 7).

The burned human bones vary in color from black (Munsell 2.5Y 2.5/1), through gray/brown (2.5Y 6/1-2), to white (calcined) (2.5Y 8/1). Temperatures associated with these colors are 300° to 360°C, 400° to 525°C, and 645° to 800°C or above, respectively (8, 9). Burning duration could have ranged from 1 to 3 hours (9, 10). This heterogeneity in combustion reveals that the skeletal elements were not extensively stirred in the fire. The posterior occipital is black, with a sharp line of demarcation to gray/brown (fig. S3). Parietal and remnant frontal fragments transition from gray/brown to white. Some long bone fragments are black, though most postcrania are lighter in color. Fragile facial and postcranial bones are largely absent. In agreement with the in situ mapping, the individual was likely supine with the body inclined somewhat toward the right, on or near the hearth floor. The position of the body likely shielded the back of the head and part of the body from the hottest temperatures, and/or the black color resulted from direct contact with the soil, which can prevent bone carbonization (9). The body was angled relative to the long axis of the dune and nearby Tanana River, with the head oriented toward the southwest (~245°). The lower limbs were probably flexed, given the proximity of the ribs near the edge of the pit and lack of preserved lower limb elements. Beyond the anatomically approximate in situ distribution of skeletal elements, transverse fracturing and extensive warping of all fragments suggest that soft tissue was present at the time of burning.

Less than 20% of the skeleton survived, including much of the posterior cranium, fragments of most deciduous and unerupted permanent teeth (i.e., unidentifiable enamel pieces, along with deciduous roots and incomplete permanent crowns protected by alveolar bone), and some postcrania. No indications of anomaly, pathology, or trauma are evident. The postcranial elements primarily comprise ribs, some sections of upper limb cortical bone and, surprisingly, many fragile elements from both hands, positioned to the right of the axial elements. Most vertebral centra and arches, the scapulae, clavicles, innominates, and almost all bones of the legs and feet are absent.

Some refitting is possible, but the postcrania are too incomplete to allow osteometric measurements for aging. However, the state of dental eruption (11) is consistent with an age of around 3 ± 1 years (figs. S4 and S5). Variation in individual tooth formation supports this estimate. Liversidge and Molleson’s (12) method for deciduous teeth yields a minimum of 1.98 ± 0.31 years and a maximum of 3.48 ± 0.69 years; most estimates are between 2.38 ± 0.35 to 2.87 ± 0.53 years. Similar findings were obtained with an alternative approach (13, 14) for deciduous and permanent teeth; on the basis of charts for males, the minimum age is roughly 1.9 years ± 8 months and the maximum is 4 years ± 6 months; other ages lie between 2 and 3 years—with most near the higher end of this range. On the basis of these estimates, the USRS human remains represent the second youngest individual of this period recovered in the Americas, after Anzick (15).

Although samples of deciduous or permanent teeth from populations are necessary to indicate biological affinity, some general information can be gleaned on an individual level. Slight shoveling and double shoveling in the unerupted permanent upper incisors and canines, among other diagnostic traits (16), are suggestive of a Sinodont pattern characteristic of Northeast Asians and Native Americans (17).

Skeletal sex determination of children is problematic; in the present case it is impossible because the most sexually dimorphic elements, i.e., mandible and innominates (18, 19), are missing.

All identifiable faunal remains in this cultural layer were found within the pit, mostly below the human cremation. The assemblage is dominated by salmonid fish and small mammals (Table 1). The presence of ground squirrels with unfused epiphyses and salmon signify a mid-summer occupation. Multiple avian taxa were represented, primarily Tetraoninae (ptarmigan). Initial analyses indicate that complete carcasses were brought to the site and processed. Different elements from food animals are represented, and most fragments are <2 cm in size, likely due to differential preservation and fragmentation or burning (20, 21). More complete element representation of microtines suggests that whole animals (or in the case of ground squirrels, the remains of cooked animals) were deposited in the pit/hearth. Differential burn temperatures, lack of articulation, and high fragmentation suggest that some remains were not associated with the burial but accumulated during separate cooking or hearth-cleaning events.

Table 1

Identified fauna from burial pit–hearth and house floor.

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More than 350 lithic artifacts were found directly associated with the house feature, most (86%) concentrated near the eastern edge (Fig. 3). The debitage consists of generally small (79% are <1 cm) tertiary flakes, related to late-stage tool maintenance rather than tool production. Four used pieces are associated with the house and pit: a unifacially retouched flake, two flakes with light edge modification, and a biface. Additional bifaces were in the Main Block (Fig. 4). Technological characteristics and local concentrations of the artifacts suggest activity areas where tools were used and discarded. No evidence of grave goods (e.g., ornaments) was found, though two small ochre fragments were present within the pit-hearth near the human and may represent ritual activities at the time of burial.

Fig. 4

Lithic tools from Component 3: bifaces (A, E to H), modified flakes (B and C), unifacially retouched flake (D). (B) to (D), and (F) were found in direct association with the house floor and burial pit; (A) was found ~13 cm below the house floor; and (E), (G), and (H) were found near hearth features in the Main Block.

Cultural chronologies for central Alaska are debated, but currently two broad interpretations for the late Pleistocene–early Holocene are as follows: (i) a single broad technological tradition with variation based on habitat use, seasonality, and mobility patterns (2224); and (ii) multiple technological traditions representing different populations (2, 25, 26). The USRS lithics, site structure, faunal data, and differences (e.g., lack of microblade technology, broader range of faunal resources, presence of residential features) relative to coterminous sites in the region (27, 28) support the former interpretation. Although the sample is small, the bipointed bifaces are similar to those of other Denali Complex specimens from Carlo Creek (29), Dry Creek Component 2 (30), and Houdini Creek (31) and unlike bifaces associated with the Nenana, Mesa, and Sluiceway Complexes (25, 26, 31, 32). USRS Component 3 appears to be most closely associated with the regionally ubiquitous Denali Complex (or Paleoarctic tradition) (33).

Only one other ancient burial site is known for Beringia: Ushki Lake 1, in Kamchatka, Russia (3437) (Fig. 1). Ushki Lake 1, Level 7 (Ushki L7) (~13,000 cal yr B.P.) contained an adult burial associated with bone beads in a rock-lined ochre-filled pit separated from the house structures. Ushki Lake 1, Level 6 (Ushki L6) (~12,000 cal yr B.P.) is roughly contemporaneous with USRS Component 3 and contains two unburned burials of children within two separate houses (35, 36). One child burial contained ochre, a pendant, a mat of lemming incisors, and numerous microblades and wedge-shaped cores (the second burial is undescribed) (35). Thus, the USRS burial context is more like Ushki L6 than L7. This replicates technological linkages between continents: Diuktai Culture of Ushki L6 is comparable with the Denali Complex, which dominates the record from 12,000 to 6000 cal yr B.P. in interior eastern Beringia (24, 38), whereas the Ushki Culture of Ushki L7, associated with stemmed points and lacking microblades, arguably has no direct counterpart in North America [(39), but see (34)].

North American human remains of this antiquity are uncommon (Fig. 1). Many were found in nonburial contexts, including the only other early eastern Beringian find, at On-Your-Knees Cave (40); the latter is about 1000 calendar years younger than the USRS child (41). The USRS burial shares few similarities with Paleoindian burials from North America, including those within pits at Arch Lake, Buhl, Gordon Creek, Horn Shelter 2, Spirit Cave, Mostin, Whitewater Draw, and Wilson-Leonard II (2, 42, 43). No Paleoindian remains were found within houses, and cremations are known only from Marmes (44) and Spirit Cave (45). Associated artifacts interpreted to be grave goods vary by site, but ochre is relatively common. Child burials are rare in early contexts, though Anzick (Clovis age) contained a child with numerous ochre-stained artifacts (15). Thus, USRS appears more similar to burials in northeast Asia than in central North America, although samples are small.

The USRS semisubterranean house shares some similarities with the only other known Beringian site with houses: Ushki L6 (n = 12 houses). Floors at that site were excavated up to 50 cm (35) and ranged from 9 to 44 m2 in area (36), sufficient for small groups of individuals. Both USRS and Ushki L6 contain child burials in pits within house floors, though the latter were not cremations. Differences include central stone-lined hearths (not pit-hearths) and entrance tunnels at Ushki L6. Six houses exhibit small pits within their floors, eight have postmolds around the periphery of the house floor, and four have them around the hearth (36). The USRS postmold distributions appear similar to those in Ushki L6 houses. Cache pits were found within Ushki L6 houses, including one with dimensions similar to those of the USRS pit.

The fish- and small game–dominated assemblage and few formal tools at USRS can be compared with the few other Beringian sites containing preserved fauna, particularly Broken Mammoth Cultural Zones 3 and 4 where birds and small mammals combined constitute 62% and 89% of the total number of identified specimens (NISP), respectively (46). Fish were found in small quantities at Broken Mammoth Cultural Zone 3 (46). The pattern of broad-spectrum fauna with bifacial and expedient tools at these components can be contrasted with the microblade- and composite point–dominated assemblage with multiple wapiti and bison at Gerstle River Component 3, a Denali Complex fall occupation (27). The USRS evidence suggests that multiple subsistence strategies operated within a single archaeological tradition, the Denali Complex: (i) economic specialization, geared to capturing large ungulates in the context of logistically organized hunting groups and short-term camps; and (ii) broad-spectrum foraging in the context of local foraging parties near residential base camps. Similarities in location, house form, burial practices, and possibly fauna between Ushki L6 Diuktai Culture [also with large and small mammals, birds, and fish (34)] and USRS Component 3 suggest similar settlement and habitat use, i.e., residential occupations near large rivers accessing a broad spectrum of resources. However, notable differences between Ushki L6 and USRS complicate comparisons; at the former, semisubterranean houses were interpreted as winter dwellings interspersed with more ephemeral houses interpreted to be summer dwellings, indicating year-round habitation (36).

A reasonable sequence of events at USRS can be inferred from these data. A small social group, including adult females and young children, foraged from their residential base camp in mid-summer, acquiring locally available fish, birds, and small mammals. The pit was dug within the house and functioned as a cooking hearth, cooking debris disposal area, and/or cache pit. The child died and was placed within the pit, with little evidence of disturbance after cremation. The pit was backfilled soon after burning, and the relative lack of artifacts atop the pit fill suggests immediate abandonment of the house (Fig. 3).

Supporting Online Material

www.sciencemag.org/cgi/content/full/331/6020/1058/DC1

SOM Text

Figs. S1 to S5

Table S1 and S2

References

References and Notes

  1. The site name is a translation of a nearby Athabaskan placename, Xaasaa Na’. The site was previously named “Little Delta Dune.” The individual has been named Xaasaa Cheege Ts’eniin (or Upward Sun River Mouth Child) by the local Native community.
  2. P. J. Reimer et al., IntCal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP. Radiocarbon 51, 1111–1150 (2009).
  3. This project was funded by the NSF (grants 0813819 and ARC-1057448). We thank J. Polston, First Chief of Healy Lake Tribal Council, and J. Isaacs, president and CEO of Tanana Chiefs Conference, for their support. We also thank the Northern Land Use Research, Inc., for field support; O. Davis and C. Alix (wood identification); and K. Blood and R. Bowman (laboratory assistance). We thank D. Meltzer, J. Hoffecker, and an anonymous reviewer for their comments.
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