INTRODUCTION

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

During the past decade it has become apparent that the human biological and cultural evolutionary transitions between late archaic (Neandertal) and early modern humans and between the Middle and Upper Paleolithic occurred relatively late throughout most of Iberia (1-4). It is now certain that the Middle Paleolithic of most of Iberia south of the Pyrenees lasted until about 30,000 years B.P., perhaps as late as 28,000 years B.P., and that the initial stages of the Upper Paleolithic known to have occurred further north (the Châtelperronian and the early Aurignacian) were never present in this region. Moreover, human paleontological evidence from Zafarraya in southeastern Spain indicates that late Middle Paleolithic technology from this region was the product of Neandertal populations (5). This evidence has led to hypotheses as to why Middle Paleolithic Neandertals endured in the cul-de-sac of Iberia between 5,000 and 10,000 years after they had been replaced (by whatever historical processes) elsewhere in Europe (4, 6, 7). The "Ebro Frontier" model (3, 6-8) suggests that the basin of the Ebro river of northern Spain represented a biogeographical and ecological barrier to the diffusion of the Upper Paleolithic innovations developed by late Neandertal populations to the north (the Châtelperronian) and, subsequently, to the dispersal of the first modern human groups in western Europe.

Even though both the late Middle Paleolithic and early Upper Paleolithic are increasingly well known and chronologically situated south of the "Ebro Frontier" (4, 6, 9), diagnostic human remains associated with early Upper Paleolithic industries in this region have been elusive. The discovery of a largely intact early Upper Paleolithic child's burial at the Abrigo do Lagar Velho in Portugal therefore adds significantly to our knowledge of the biology and burial practices of the earliest Iberian modern humans and sheds light on the nature of the transition from Neandertals to their successors in one of the last archaic human frontiers.

	THE ABRIGO DO LAGAR VELHO

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

The archeological site consists of deposits within horizontal fissures and along the current base of a limestone cliff on the south side of the Lapedo Valley near Leiria, central western Portugal (lat 39° 45' 25" N, long 8° 43' 58" W). The site was damaged by earth removal in 1992, exposing an Upper Paleolithic sequence and coming within a few centimeters of the burial along the base of the cliff. On November 28, 1998, the site was discovered by J.M. and P.S., who also found the left hand and forearm bones of the child in a burrow. The following week C.D. and J.Z. confirmed the presence of Paleolithic deposits and a human burial. A salvage excavation directed by J.Z. ensued from December 12 to January 7, 1999, in the framework of which the burial was excavated by C.D. Paleontological analysis by C.D. and E.T. commenced on January 4, 1999.

The child's skeleton, Lagar Velho 1 (Fig. 1), was on its back parallel to the cliff base, with the head to the east and left side against the cliff. The cranium and mandible were damaged by earth removal, but the preservation of the left temporal bone and mandible indicates that the head had tilted toward the cliff face. The collapse and folding in situ of the right ribs suggest that the thorax was similarly tilted. The pelvis was horizontal, and the feet were plantar-flexed and crossed. The skeleton and the containing sediment are heavily stained with red ochre, but the alteration of the sediment stopped at the outer border of the skeleton, suggesting a wrap around the body. Vertically oriented animal bones and stones outlined the ochre-stained sediments; radiocarbon dating of one such bone yielded a result that is consistent with the hypothesis that these represent intentional burial features and not a natural disposition of deposit components caused by digging a burial pit.

View larger version (160K): [in this window] [in a new window]   Fig. 1.   Lagar Velho 1 in situ, with damaged skull and left forearm elements already removed.

The only diagnostic archeological item in the burial was a pierced Littorina obtusata shell found near the cervical vertebrae; it is identical to those from Level Jb of the nearby site of Gruta do Caldeirão (Tomar) dated to 26,020 ± 320 years B.P. (OxA-5542; ref. 6). Similar burials with pierced shells and/or teeth and a covering of ochre are known particularly from the Gravettian of Europe, especially from Britain (Paviland), Italy (Arene Candide, Barma Grande, Caviglione, Ostuni), and the Czech Republic (Brno, Dolní Vstonice; refs. 10-12).

The uppermost 2-3 m of the shelter's fill were largely removed and current ground level represents the surface of an estimated 3- to 4-m sequence of early Upper and possibly Middle Paleolithic strata. A 60-cm thick hanging remnant is preserved within a fissure running along the back wall of the shelter and contains a Proto-Solutrean (level 6) through Middle Solutrean (level 9) sequence. In Portugal, assemblages with diagnostic laurel-leaf point fragments date to ca. 20,000-20,500 years B.P., and the Proto-Solutrean dates to ca. 21,500 years B.P. (6, 13). Radiocarbon dating of charcoal from level 9 yielded a date of 20,200 ± 180 years B.P. (OxA-8419), and samples of charcoal from level 6 yielded results of 21,180 ± 240 years B.P. (OxA-8420) and 21,380 ± 810 years B.P. (Sac-1561); a stratigraphically less reliable level 6 sample yielded 22,180 ± 180 years B.P. (OxA-8418).

The position of the burial, 2.5 m below the Proto-Solutrean remnant, as well as its archeological resemblances to Gravettian burials elsewhere, suggests an age several millennia earlier. This inference is supported by accelerator mass spectrometry radiocarbon dating of charcoal [24,860 ± 200 years B.P. (GrA-13310)] and Cervus elaphus remains [24,660 ± 260 years B.P. (OxA-8421) and 24,520 ± 240 years B.P. (OxA-8423)] directly associated with the burial and of a vertebra from a semiarticulated section of a Oryctolagus cuniculus vertebral column [23,920 ± 220 years B.P. (OxA-8422)] immediately overlying the legs. The burial therefore occurred between 24,000 and 25,000 years B.P. and probably between 24,500 and 25,000 years B.P.

	AGE AND BODY SIZE

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

The remains are those of a juvenile (Figs. 1 & 2). All of the deciduous teeth (right di₂ to left dm₂ plus left dc¹ and dm²) have apically closed roots, indicating a median minimum age of 3.0 years. The I₂ is almost at Cr_c; the C¹ is C_3/4; the P₄ is C_co; the M¹ and M₁ are R_1/4; and the M₂ is C_oc (nomenclature established by Moorrees et al.; ref. 14). The levels of calcification for the latter four teeth provide median ages (male/female) of 3.4/3.5, 3.9/3.9, 4.9/4.8, and 4.9/4.5 years, by using Euro-American standards (15). The average estimate is 4.2 years postnatal, and the probable range is 3.5-5.0 years.

View larger version (73K): [in this window] [in a new window]   Fig. 2.   Lingual view of the mandible and dentition, showing the degrees of dental development, the symphyseal retreat, and the prominent right tuberculum laterale. (Black bar and white bar = 1 cm each.)

The more complete right femur has an intermetaphyseal length of 198 mm plus proximal and distal epiphyseal thicknesses of 10.0 mm and 13.3 mm, respectively. Adding these and rounding up because of the absence of the epiphyseal cartilages provides an interepiphyseal length of 225 mm. Estimates from the ratios of 4- to 18-year-old modern Euro-American mean femoral lengths (16) predict adult femoral lengths of 450 mm (male) and 410 mm (female). These values are below the means for adult European earlier Upper Paleolithic males (478.0 ± 21.4 mm; n = 13) and females (427.3 ± 19.0 mm; n = 9) but within their ranges of variation; the values are close to the means for Neandertal males (443.3 ± 18.7 mm; n = 11) and females (400.3 ± 14.2 mm; n = 3).

	MORPHOLOGICAL CONSIDERATIONS

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

Materials and Methods. This preliminary assessment of Lagar Velho 1 is concerned with its morphological affinities to northwestern Old World late archaic humans (Neandertals) versus early modern humans. The latter sample consists predominantly of Aurignacian and Gravettian remains between 20,000 and 30,000 years B.P. Given the dearth of earlier Upper Paleolithic juvenile human remains, the comparisons also involve Near Eastern Middle Paleolithic (Qafzeh-Skhul) early modern humans. Recent human comparative data are included as appropriate, the samples deriving from temperate European and North American samples (17-19). The relative positions of the fossil specimens in the postcranial proportional assessments are based on distributions of raw residuals from the reduced major axis lines for the recent human samples and are expressed as z scores.

The Temporal Bone. The mastoid region in the left temporal bone is preserved with little damage. It has a clear juxtamastoid eminence, which extends to the same level as the mastoid process tip. The relative sizes of these two processes is intermediate between Neandertal juveniles with their larger juxtamastoid eminences (20) and early modern humans with their more projecting mastoid processes (21, 22).

The Mandible. The anterior mandibular symphysis has the full development of a mentum osseum (Fig. 3). There is a very prominent tuber symphyseos with an exceptionally protruding tuberculum laterale on each side. These combine to create a deeply excavated incisura mandibulae anterior. The midline of the tuber symphyseos extends superiorly toward the alveoli. By any criteria, this symphyseal configuration is a prominent development of a "chin," clearly distinct from the modest development of these elements in similarly aged Neandertals (19, 23) and pronounced even for a developmentally comparable modern human (21, 24).

View larger version (104K): [in this window] [in a new window]   Fig. 3.   Anterior view of the mandibular symphysis showing the development of the mentum osseum. Symphyseal height = 24.7 mm.

The Dentition. The deciduous dental remains have no macroscopic pathological alterations and minimal incisor attrition. The first molar crown diameters (Table 1) are similar to those of Neandertals and early modern humans, who are not significantly different in these dimensions. The I₂ breadth shows a gradual decrease from Neandertals to Qafzeh-Skhul humans to earlier Upper Paleolithic humans to recent Europeans, and Lagar Velho 1 falls between the means of the last two samples. Late archaic and early modern humans differ more in their anterior-to-posterior dental proportions than in absolute dental dimensions (26), and the relative I₂ versus M₁ breadths of Lagar Velho 1 fall with the early modern humans and separate from the Neandertals.

The Postcranial Remains. At least one of each of the major long bones was preserved in the appendicular skeleton of Lagar Velho 1, with only the radius lacking a complete intermetaphyseal length (Fig. 4). The intermetaphyseal maximum lengths (left side for all but the femur) are, for the humerus, 143 mm; for the ulna, 122.5 mm; for the femur, 198 mm; and for the tibia, 155 mm. The clavicles are not sufficiently preserved to provide lengths, and major portions of the pelvis remain.

View larger version (76K): [in this window] [in a new window]   Fig. 4.   Anterior view of the long bones. (Black and white bars = 1 cm each.)

View larger version (15K): [in this window] [in a new window]   Fig. 5.   Midshaft circumference versus femoral intermetaphyseal diaphyseal length (Upper) and versus tibial intermetaphyseal length (Lower). Black hexagon, Lagar Velho 1; gray pentagons, European Neandertals; gray squares, Qafzeh-Skhul humans; open triangles, cool-temperate recent humans.

	DISCUSSION

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

These morphological considerations provide a mixed impression of the Lagar Velho 1 juvenile early Upper Paleolithic human skeleton relative to northwestern Old World Neandertals and early modern humans. It is buried in a distinctively early Upper Paleolithic pattern, but its morphology is a mosaic of Neandertal and early modern human features.

The temporal juxtamastoid eminence development is intermediate between these two groups. The mandibular mentum osseum and dental proportions align it completely with the early modern humans. This alignment is supported by mandibular ramal discrete traits, orientation of the radial tuberosity, radial curvature, and relative pubic breadth. The femorotibial length proportions and lower limb hypertrophy (femoral and tibial diaphyseal robusticity and tibial condylar posterior displacement) indicate hyperarctic Neandertal body proportions distinct from those of European earlier Upper Paleolithic humans. In addition, the mandibular symphysis retreats at an archaic angle, and the thoracohumeral muscle insertions are most similar to those of the Neandertals.

The body proportions of Iberian Neandertals are not known, but all European Neandertals, including the Châtelperronian St. Césaire 1, have hyperarctic body proportions (41, 50). It is therefore likely that the Iberian Neandertals either had similar body proportions or, given the more temperate glacial climate of coastal southern Iberia (6), had less extreme cold-adapted proportions. All of the European earlier Upper Paleolithic human remains have subtropical body proportions, whether measured directly or inferred from femoral and tibial diaphyseal scaling (32, 42, 43). The more moderate oxygen-isotope stage 3 climate of southern Iberia versus the climate known for southwestern France or central Europe makes it unlikely that the inferred cold-adapted body proportions of Lagar Velho 1 were the product of regional climatic selection. They can only indicate affinities to the Neandertals.

Although some of these features are developmentally plastic, the mandibular and dental patterns as well as the ecogeographically related body proportions seem to be resistant to environmental perturbations and to be evolutionarily stable over at least the millennia of concern. They are therefore appropriate markers for assessing the ancestry of Lagar Velho 1.

There are two logical explanations for the morphological mosaic seen in Lagar Velho 1. It could represent the ancestral (plesiomorphous) pattern for Late Pleistocene European humans, or it could be the result of admixture between European late archaic and early modern humans. The first explanation can be rejected by the presence of a uniquely derived (autapomorphous) feature of modern humans, its mentum osseum development, supported by its chronological position after the presence of both Neandertals and early modern humans in Europe.

The morphological mosaic of the Lagar Velho 1 child therefore indicates admixture between early modern humans spreading through Iberia and local Neandertal populations. Such morphological mosaics, with character states distinctive to each parental group (directional dominance), plus intermediate (additive) or divergent (overdominance or underdominance) configurations, characterize hybrids between subspecies, species, and genera of primates and carnivores (51-55). It is not known whether any one mosaic pattern would be expected, given specified ancestral morphological patterns, nor is it known how stable the pattern is likely to have been over time. However, the mosaic seen in Lagar Velho 1 conforms to the known patterns of hybridization.

Moreover, the dating of the burial to several millennia after the probable period of transition from Neandertal to early modern human in southern Iberia (28,000-30,000 years B.P.), and hence the persistence of a morphological mosaic for that time period, indicates that this child was not the result of a rare Neandertal/early modern interbreeding but the descendant of extensively admixed populations. There does not seem to be a better means of explaining why, in spite of sharing a similar material culture and identical burial practices with the Gravettian elsewhere in Europe, Lagar Velho 1 is anatomically so distinct.

The presence of such admixture supports the hypothesis (56, 57) of variable admixture between early modern humans dispersing into Europe and local Neandertal populations. It runs counter to the interpretation (58, 59) that, in western Europe, this transition involved the extinction without descent of the Neandertals and their complete replacement by dispersing early modern humans with more elaborate technological and sociocultural systems.

The broader implications of this finding are multiple. First, it means that the degree of abruptness in sociocultural and technological complexes around the time of the transition from the Middle to Upper Paleolithic need say little about the degree of human biological population continuity. Second, the geographical location and temporal position of the transition need not constrain the degree to which there was admixture between local archaic and early modern human populations. Third, it is inappropriate to apply a species distinction with strict implications of reproductive isolation to the Neandertals versus early modern humans. And fourth, hypotheses (60-63) that full population replacement of late archaic humans by early modern humans took place everywhere outside of the (presumably African) core area of modern humans can be rejected. It is therefore necessary to go beyond the categorical models that have been used commonly to characterize the late archaic to early modern human and the Middle to Upper Paleolithic transitions and to recognize the complex regional, temporal, human biological, and cultural processes as well as historical trajectories that took place.

	CONCLUSION

TOP ABSTRACT INTRODUCTION THE ABRIGO DO LAGAR... AGE AND BODY SIZE MORPHOLOGICAL CONSIDERATIONS DISCUSSION CONCLUSION REFERENCES

The early Upper Paleolithic human burial at Lagar Velho, Portugal, provides evidence of the burial practices and human biology of these Late Pleistocene human populations. The burial, with pierced shell ornamentation and red ochre, is similar to Gravettian ones elsewhere in Europe. The facial and appendicular remains provide a morphological mosaic, with the mandibular mentum osseum and dental proportions, as well as mandibular ramal, antebrachial features, and pubic size, aligning the specimen with European early modern humans. The mastoid region is intermediate; however, the femorotibial length proportions and lower limb hypertrophy reflect arctic body proportions, and these features, along with the mandibular symphyseal retreat and thoracohumeral muscle hypertrophy, indicate affinities to the Neandertals. This mosaic indicates admixture between late archaic and early modern humans in Iberia, refuting hypotheses of complete replacement of the Neandertals by early modern humans and underlining the complexities of the cultural and biological processes and events that were involved in modern human emergence.