Quaternary International 109–110 (2003) 123–132 Early peopling and evolutionary diversification in America H!ector M. Pucciarellia,b,*, Marina L. Sardia, Jos!e C. Jimenez L !opezc, Carlos Serrano Sanchezd aDivisi !on Antropolog!ıa del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina bConsejo Nacional de Investigaciones Cient!ıficas y T!ecnicas, Avda. Rivadauia 1917, 1033 Buenos Aires, Argentina c Instituto Nacional de Antropolog!ıa e Historia (INAH), Mexico DF, Mexico d Instituto de Investigaciones Antropol !ogicas, Mexico DF, Mexico Abstract Several cranial-functional studies were made to compare the major (neurocranium and face) and minor (anteroneural, midneural, posteroneural, otic, optic, respiratory, masticatory, and alveolar) cranial components in different human populations. In the present study, samples from Paleoamericans and ancient and modern Amerindians from Valley of Mexico, Lagoa Santa, Tierra del Fuego Island, and Minas Gerais (Botocudos) were compared. The aim was to test the hypotheses that (1) ‘‘There are non-significant differences in the functional cranial components of different Paleoamerican crania, since they proceeded from a single dispersive effect’’ and that (2) ‘‘The biological variability of Paleoamerican and Amerindian functional cranial components was produced by random diversification evoked—after migration—by stochastic evolution’’. Its acceptance will hold the criterion of temporal discontinuity between ‘‘megapopulations’’, with a high incidence of migration and genetic drift. Its rejection will mean that Paleoamericans were not a morphologically homogeneous substratum, and that further populations could have—at least in part—originated from one or several central nuclei highly diversified by non-stochastic processes, like selection and adaptation. Multivariate (discriminant analysis and hierarchical clusters) were employed to get a general sample distribution. Univariate between-group standardized sD2 distances were calculated to measure absolute and relative within-component differences. Statistical analyses were performed by the SYSTAT 9 program. Results lead us to reject both null hypotheses, suggesting that: (1) some cranial-functional differences were evident between both Paleoamerican samples, and (2) that several adaptative trends from Paleoamericans to modern Amerindians, and between Amerindians, might have occurred. It was concluded that adaptation could explain a fraction of the non-detectable cranial variation by the non-functional craniometric methods not explained by the ‘‘migration-drift’’ model for the American diversification. r 2002 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction Several attempts to explain the origin and diversity of South-American human populations were made. Until the mid-20th century, the explanations were, except for Ameghino’s valuable efforts, based purely on migration. In essence, a ‘‘migratory wave’’ for each morphological type had been considered. The origin and number of such waves varied in function of the number of observable morphological types, which were seldom influenced by the subjectivism of the observer. The intermediate types were explained by miscegenation among contemporary waves. Such an extremely diffu- sionist paradigm was replaced about 1950 by the point of view that migration is just one evolutionary mechan- ism. Genetic drift was the other one. Later, non- stochastic processes such as adaptation were proposed by Lahr (1995) and Hern!andez et al. (1997), among other authors.We believe that such a complex process as the peopling of a continent through, at least, a hundred centuries, is only explainable by multiple factors, such as migration, genetic drift, and adaptation. From the 1980s onwards, several explanatory hypotheses about human settlement in the Americas were proposed. They were based on one (Bonatto and Salzano, 1997a, b; Merri- wether et al., 1995; Szathm!ary, 1981, 1984), three (Greenberg et al., 1986; Lahr, 1995; Turner, 1987, 1992), and four (Neves and Pucciarelli, 1990, 1991, 1998; Neves et al., 1999a, b; Powell and Neves, 1999; Steele ARTICLE IN PRESS *Corresponding author. Division Antropologia del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina. E-mail address: hmpucci@fcv.unlp.edu.ar (H.M. Pucciarelli). 1040-6182/02/$ - see front matter r 2002 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/S1040-6182(02)00208-2 and Powell, 1992, 1993) possible migrations. Now, the problem should be analyzed from two perspectives. One of them is to reconsider the number of population components rather than the number of migratory waves, and the other one is to introduce adaptation as an actual differentiation process in the Americas. The first topic came from an interesting question. At the end of the 1980s, the Three-Migration Model (TMM), based on dental, genetic, and linguistic traits, was generally accepted for the American peopling. The TMM postulated three population waves, one for Eskimos, another for Na-Dene and a third one, in fact the first, for the remaining Amerindians. The Four- Migration Model (FMM) was built on the TMM basis, since the fourth wave was added to explain the first American settlement, that of the Paleoamericans, about 12,000–8000 years ago. Further linguistic, non-metric, mtDNA, and ‘‘Y’’ chromosome studies made between Na-Dene and American Eskimos (Ossenberg, 1976; Szathm!ary and Ossenberg, 1978; Szathm!ary, 1979; 1993) did not indicate that both groups were actually different. Consequently, the TMM was seriously con- strained, by reducing from three to two the number of migratory waves, and the FMM became the TMM. A more rational model, however, would be the Two- Component settlement System (TCS). This model avoided the untesteable concept of ‘‘wave’’ in favor of the more tangible concept of ‘‘component’’, since, on the one hand, in more than one migratory wave the Amerindians could people the continent, and, on the other hand, different peoples could come forth from a single migration. A component, in the TCS, may be one, two, or several populations that, sharing similarity in morphology and antiquity, compound a true megapo- pulation, independent of the number of migratory waves supposed to happen. The system is the autochthonous American people and the components are the Paleoa- mericans (12,000–8000 BP), the ancient (8000–500 BP), and modern (o500 BP) Amerindians. The first ones were non-Mongoloid people, morphologically near the South-Africans and Australians, and some of them might have survived to the present. The second ones were Mongoloids, or with mongolized cranial and facial structures. They came from North Asia and constituted great part of the extinct and extant Amerindian populations. The second component is the main subject of the present study, which points to the fact that the autochthonous American variability may be due, at least in part, to non-stochastic evolutionary processes. It is possible that, given the knowledge about the popula- tion density of the Paleoamerican times, they may have evolved and, if not banished by the Amerindians, survived up to modern times. Functional cranial studies made on American skulls allowed us to conclude that, beyond the mere taxonomic implications drawn from the classical craniometrical methods, the evolutionary adaption played an important role in the American diversifying processes (Pucciarelli et al., 1999). Such studies are based on the Functional Cranial theory, proposed by van der Klaauw for the mammalians (Klaauw, 1948–52), and by Moss and Young (1960) for the human skull. In substance, the Klaawesian theory considers the skull as formed by several skeletal units, relatively independent, and suitably differentiated by their support and protection functions to the head soft tissues and organs (Dressino and Pucciarelli, 1999; Pucciarelli et al., 1990, 1999). The aim of the present study was to examine the null hypotheses that (1) ‘‘There are non-significant differ- ences in the craniofacial structure of Paleoamerican crania, whether they proceeded from a single dispersive effect’’; and that (2) ‘‘The biological variability of Paleoamerican and Amerindian functional cranial components was produced by random diversification evoked (after migration) by stochastic evolution’’. The acceptance of the two hypotheses will hold the criterion of temporal discontinuity between the megapopulations, with high incidence of migration drift. Their rejection will mean that, on the one hand, Paleoamericans were not a morphologically homogeneous substratum, and that, on the other hand, further populations could be, at least in part, originated from one or several central nuclei highly diversified by non-stochastic processes, like selection and adaptation. 2. Material and methods Sixty male skulls from hunter–gatherer populations were employed. They came from Mexico, Brazil, and Argentina. Mexican crania belonged to four Paleoamer- icans (Valley), nine Archaic Amerindians (Tlatilco), and six modern Amerindians (Tlatelolco), all belonging to the Instituto Nacional de Antropolog!ıa e Historia (INAH, Mexico DF). The South American samples were ten Paleoamericans (Lagoa Santa) belonging to the Harold Walter collection (Minas Gerais Museum, Brazil), eleven Amerindians, belonging to the Minas Gerais (Botocudos) (Rio de Janeiro Museum, Brazil), and ten Amerindians coming from the southernmost part of Argentina (Fuegians) (La Plata Museum, Argentina). The limited reliable radiocarbon data are enough to assure, on average, antiquities of 10,000BP for Valley (Tlapacoya), 9000BP for Lagoa Santa, (Lapa Vermelha, Santana do Riacho), and at least 5000 BP for the Mexican Archaics (Texcal, Tepexpan). The 30 variables belonging to the functional cranio- metrical method, i.e., a length ðLxÞ; a width ðWxÞ; and a height ðHxÞ for each major (neurocranium and face), and minor neurocranial (anteroneural, midneural, pos- teroneural, and otic), and facial (optic, respiratory, ARTICLE IN PRESS H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132124 masticatory, and alveolar) functional components, were measured (see Tables 1 and 2 for description). Ten volumetric indices ðVIxÞ; for estimating the absolute size of the components, were built as the geometric mean from the three orthogonal dimensions measured into each component. Nine morphometric indices ðMIxÞ were also built for measuring shape in terms of relative size differences between minor functional components, and with respect to the major component to which they belong. The VIx is calculated as VIx ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ðLxWxHxÞ 3 p The volumetric indices (VI) calculated for the neurocranium were: the neurocranial (NVI), antero- neural (ANVI), midneural (MNVI), posteroneural (PNVI), and otic (OTVI) ones. For the face, the facial (FVI), optic (OVI), respiratory (RVI), masticatory (MVI), and alveolar (AVI) ones were employed. The morphometric indices are useful to describe shape changes of the functional components, in terms of relative size variation with respect to the remaining ones involved in the major component to which they belong MIx ¼ 100VIx=VIt where Neurocranial VIt ¼ ANVIþMNVIþ PNVIþOTVI Facial VIt ¼ OVIþRVIþMVIþAVI ARTICLE IN PRESS Table 1 Variables employed in this study Number Symbol Name Description Instrument Modea 01 NL Neurocranial length Nasion-Opisthocranium Poech Caliper Projected 02 NW Neurocranial width Eurion-Eurion Curved Branch Caliper Direct 03 NH Neurocranial height Basion-Vertex Poech Caliper Projected 04 FL Facial length Inner Prosthion-Vomerobasilar Poech Caliper Projected 05 FW Facial width Zygion-Zygion Curved Branch Caliper Direct 06 FH Facial height Nasion-Prosthion Poech Caliper Projected 07 ANL Anteroneural length Glabella-Bregma Poech Caliper Projected 08 ANW Anteroneural width Pterion-Pterion Poech Caliper Direct 09 ANH Anteroneural height Bregma-Vomerobasilar Poech Caliper Projected 10 MNL Midneural length Bregma-Lambda Poech Caliper Projected 11 MNW Midneural width Same as NW Curved Branch Caliper Direct 12 MNH Midneural height Basion-Bregma Poech Caliper Projected 13 PNL Posteroneural length Opistion-Opisthocranium Poech Caliper Projected 14 PNW Posteroneural width Asterion-Asterion Curved Branch Caliper Direct 15 PNH Posteroneural height Lambda-Opistion Poech Caliper Projected 16 OTL Otic length Timpanic bone posterior inferior end-mid point of inner end of the petrous bone Vernier Caliper Direct 17 OTW Otic width External auditive width Needle Caliper Direct 18 OTH Otic height External auditive height Needle Caliper Direct 19 OL Optic length Dacrion-intersfenoidal foramen Orbitometer Direct 20 OW Optic width Dacrion-Ectoconquio Poech Caliper Projected 21 OH Optic height Mid-Supraorbitary point-Mid-Infraorbitary point Poech Caliper Projected 22 RL Respiratory length Subnasal-Posterior nasal espine Poech Caliper Projected 23 RW Respiratory width Maximum nasal width Vernier Caliper Direct 24 RH Respiratory height Nasion-Subnasal Poech Caliper Projected 25 ML Masticatory length Lower border zygomatic synchondrosis- posterior border of the glenoid cavity Vernier Caliper Direct 26 MW Masticatory width Anterior sulcus of the sphenotemporal crest-lower point of the zygotemporal synchondrosis Needle Caliper Projected 27 MH Masticatory height Lower border of the zygotemporal synchondrosis- upper temporal line at the coronal intersection Poech Caliper Projected 28 AL Alveolar length External Prosthion-posterior alveolar border Vernier Caliper Direct 29 AW Alveolar width From left to right second-third molars width Vernier Caliper Direct 30 AH Alveolar height Palatal deep at midsaggital/second-third molars width Palatometer Direct aFor the projected measurements, the skull must be placed laterally on a 1m squared 50� 50 cm2 white cardboard, for reaching an acceptable parallelism with the caliper bar and/or its branches. Positioning must be done rotating carefully the skull up to reach and Auricular-Infraorbitary equalization (Frankfurt line). Previously, the correct anterior-posterior and vertical placement of the skull must be done with, respectively, the equalization of the Prosthion and Inion points with respect to the horizontal plane, and of the palatal first molars perpendicularly to this plane. Frankfurt orientation can be facilitated by a nylon thread placed not more than 1 cm above the skull, and subtended parallel to one of the cardboard lines. The thread must be took away after the correct placement was reached and before measurement starts. Direct measurements may be made out of the Frankfurt orientation. It is recommended to be first all projected and then all direct measurements or vice-versa. H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132 125 For the neurocranium, the anteroneural (ANMI), midneural (MNMI), posteroneural (PNMI), and otic (OTMI) indices were employed. For the face, the optic (OMI), respiratory (RMI), masticatory (MMI), and alveolar (AMI) ones, were used. The morphometric index employed for the major components was the neural–facial (NFI) one, which relates both major components NFI ¼ NVI=FVI The NFI measures how many times the size of the neurocranium is involved in a unit of facial size. An NFI ¼ 2:0 means that two times of neurocranium per unit of facial size is contained. The higher the NFI value, the greater the ‘‘encephalization’’ degree. In human crania, it depends, in fact, much more on the facial than on the neurocranial size variation, since face variation is highly related to the overall size -stature- variation (Tables 1 and 2). The multivariate statistics employed were hierarchical clusters based on the canonical scores from the minor component variables, given by the between-group discriminant analysis. Clusters were built with average linkage type and euclidean distances, after scaling ðzÞ and size (double-z) standardizations (Figs. 1 and 2). The univariate statistics involved the one-sample non-para- metric Kolmogorov–Smirnov test, and the w2 propor- tion comparison for testing, respectively, the frequency distribution properties, and the signification of the differences in component proportions. The intensity and signification of the between-group comparisons were obtained by univariate Mahalanobis D2 distances. The distances obtained from each between-group comparison were standardized ðsD2Þ as percentual fractions in the major and minor components. For example, an sD2 ¼ �16:0 obtained for the AMI in the Valley–Lagoa Santa comparison means that the free- sized alveolar component in Lagoa Santa was 16% greater than in Valley. Samples were compared follow- ing a sequential antiquity order in which the same sample was compared twice, in a consecutive way. Different comparisons had different meanings. Fig. 3 shows the differences between Paleoamerican functional components. Fig. 4 shows the results of the South- American comparison sequence. Fig. 5 shows the results of the Mexico Valley cranial functional comparison. The statistical work was performed by the SYSTAT 9 program. The work was carried out at the Divisi !on Antropolog!ıa of the Museo de La Plata (Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Argentina). 3. Results The free of scaling hierarchical cluster made with the discriminant scores from the minor component variables (Fig. 1) showed two subclusters separated by the great- est distance ðd ¼ 4:7Þ: One for Tlatilco, Tlatelolco, and Valley, and the other for Lagoa Santa, Botocudos, and Fuegians. Valley was more separated from Tlatilco and Tlatelolco ðd ¼ 3:8Þ than Botocudos and Fuegians ARTICLE IN PRESS Table 2 Indices employed in this study Symbol Formula Description Major components Neurocranial volumetric index NVI NVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi NLNWNH3 p Facial volumetric index FVI FVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi FLFWFH3 p Neurofacial index (morphometric) NFI NFI ¼ NVI=FVI Minor components ANVI ANVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ANLANWANH 3 p Anteroneural volumetric index MNVI MNVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi MNLMNWMNH3 p Midneural volumetric index PNVI PNVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi PNLPNWPNH3 p Posteroneural volumetric index OTVI OTVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi OTLOTWOTH3 p Otic volumetric index OVI OVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi OLOWOH3 p Optic volumetric index RVI RVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi RLRWRH3 p Respiratory volumetric index MVI MVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi MLMWMH3 p Masticatory volumetric index AVI AVI ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ALAWAH3 p Alveolar volumetric index ANMI ANMI ¼ 100ANVI=ðANVIþMNVIþ PNVIþOTVIÞ Anteroneural morphometric index MNMI MNMI ¼ 100MNVI=ðANVIþMNVIþ PNVIþOTVIÞ Midneural morphometric index PNMI PNMI ¼ 100PNVI=ðANVIþMNVIþ PNVIþOTVIÞ Posteroneural morphometric index OTMI OTMI ¼ 100OTVI=ðANVIþMNVIþ PNVIþOTVIÞ Otic morphometric index OMI OMI ¼ 100OVI=ðOVIþRVIþMVIþAVIÞ Optic morphometric index RMI RMI ¼ 100RVI=ðOVIþRVIþMVIþAVIÞ Respiratory morphometric index MMI MMI ¼ 100MVI=ðOVIþRVIþMVIþAVIÞ Masticatory morphometric index AMI AMI ¼ 100AVI=ðOVIþRVIþMVIþAVIÞ Alveolar morphometric index H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132126 did between themselves ðd ¼ 2:5Þ: Lagoa Santa was more separated from Botocudos and Fuegians ðd ¼ 3:8Þ than the latters did between them ðd ¼ 2:5Þ: The hierarchical cluster made with the discriminant scores from the free of size minor component variables (Fig. 2) showed a slight shortening of the distances, but no change in the sample distributions. The behavior of the functional cranial components is shown in Fig. 3 for comparison between Paleoamer- icans. Valley had greater neurocranial (18%), and much greater facial (60%) component sizes, while the neural– facial index (�22%) was greater in the latters. The respiratory and masticatory components were greater in Lagoa Santa than in Valley (�40%, and �10%, respectively), while the alveolar one was greater in Valley (30%) than in Lagoa Santa.The remaining components (20%) were non-significant The South-American cranial differences are shown in Fig. 4. In the Lagoa Santa–Botocudo comparison, while the face (�56%) was greater in the first population, the neural–facial index (40%) was greater in the other one, the neurocranial index being non-significant (�4%). The otic (�50%), and the masticatory (�30%) compo- nents were greater in Botocudos, while the remaining components (20%) were non-significant (Fig. 4a). Fue- gians were greater than Botocudos in the facial component (�45%), while the remaining major indices (55%) were non-significant. The posteroneural compo- nent was greater in Fuegians (�18%), while the otic one was greater in Botocudos (20%), the remaining ones ARTICLE IN PRESS Fig. 1. Cluster built from the canonical discriminant scores of the ‘‘simple z’’ standardized (size plus shape) minor component variables. H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132 127 being (62%) non-significant (Fig. 4b). Fuegians were greater than Lagoa Santa in the neurocranial (10%), and facial (60%) components; while Lagoa Santa was greater in the neural–facial index (�30%). Two minor components were greater in Lagoa Santa: the optic (�22%), and the respiratory (�20%), while the masti- catory one (37%) was greater in Fuegians, the remaining (21%) components being non-significant (Fig. 4c). The cranial differences in Mexico Valley are shown in Fig. 5. In Valley–Tlatilco comparison, the facial com- ponent was greater in the former (60%), while the neural–facial index (�23%) was greater in the latter. The neurocranial component (17%) was non-significant. The respiratory component (�52%) was greater in Tlatilco, while the alveolar one (29%) was greater in Valley. The remaining ones (19%) were non-significant (Fig. 5a). The neurocranial and the facial components were greater (60% and 39%, respectively) in Tlatilco than in Tlatelolco, while the neural–facial index being non-significant (�1%). Tlatelolco was greater than Tlatilco in the posteroneural component (�49%), while the remaining ones (51%) were non-significant (Fig. 5b). The Tlatelolco–Valley comparison showed a greater neurocranium (�38%) and face (�52%) in the latter, while the neural–facial index was greater in Tlatelolco (10%). The posteroneural (20%) and respiratory (50%) components were greater in Tlatelolco, while the alveolar (�20%) one was greater in Valley. The remaining minor components (10%) were non-signifi- cant (Fig. 5c). ARTICLE IN PRESS Fig. 2. Cluster built from the canonical discriminant scores of the ‘‘double z’’ standardized (only shape) minor component variables. H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132128 4. Discussion 4.1. First hypothesis If the first hypothesis was true, then the functional component differences between Valley and Lagoa Santa should be null or nearly null. This was not supported by the results. First, gross size plus shape (Fig. 1) and shape (Fig. 2) differences can be drawn from the topologies given by the clusters, in which Lagoa Santa remained separated from Valley by the greatest distances. Second, the major component bars (Fig. 3) showed greater neurocranial and facial sizes for Valley, and a greater neural–facial index for Lagoa Santa. These results meant that the increment in size of Valley was followed by a shape effect in terms of neurocranial content per unit of facial volume. Such neural–facial disruption was expressed by the lack of the neurocranial minor-component variation, and by the significantly incremented respiratory and masticatory components in Lagoa Santa, as well as, the significantly incremented alveolar component in Valley. These facts may indicate, at least, three different adaptative trends: one associated to cold stress (respiratory), another associated to the masticatory stress, and the third marked by the statural decrement of Lagoa Santa people with respect to Valley, possibly linked to both cold and nutritional stresses. The neural–facial structure found in Lagoa Santa agreed with the small facial size found by Steele and Powell (1994) in Paleoindians of North America. Lagoa Santa crania had an apparently greater encephalized skull ðNFI ¼ 1:96Þ than Valley ðNFI ¼ 1:73Þ: In fact, we should think of a lower facialization, since the face is always more variable than the neurocranium in most of the human cranial comparisons. Due to all these considerations, the first hypothesis was rejected. 4.2. Second hypothesis If the second hypothesis was true, then randomly distributed significances in all minor functional compo- nents—‘‘mosaic distribution’’—with similar probability values about the mean value ðp ¼ 0:34Þ would be expected. Since significant deviations actually appeared, a non-randomly distributed differentiation may be accepted. Proportions actually varied from p ¼ 0:29 (otic) to 0.57 (respiratory) with highly significant ðw2po0:01Þ differences, suggesting that several adaptative trends may be identified in Meso and/or South-America. Botocudos were differentiated from Lagoa Santa by their decreased encephalization, and incremented facial, otic, and masticatory components. The facial increment was the only trend persistent in Fuegians; while the neural–facial index and the masticatory component were stopped, the otic one was reversed, in an apparently stasis period. The otic increment in Botocudos may be an exclusive attribute of this population, while the posteroneural increment was one of the Fuegians. Both were apparently not connected to any adaptative trend. With the Fuegian–Lagoa Santa comparison, almost all trends—increments in overall and facial size, and in the masticatory development, decreases in the neural–facial ratio and in the respiratory component, seen in the comparisons against Valley and Botocudos, were con- firmed. The optic reduction seemed to be an exclusive Fuegian adaptation, probably due to protection against the cold and windy climate of the southernmost region of the continent. Tlatilco was differentiated from Valley by its in- creased encephalization and respiratory gauge, and by its decreased facial size and alveolar development. Tlatelolco suffered, with respect to Tlatilco, a decrease of the overall size, and an increment of the poster- oneural development, the rest of the components being invariable. Thus, the same stasis found in Botocudo– Fuegians was supposed for Tlatelolco–Valley. Such comparison showed that almost all trends—decrease in overall and facial sizes and in the alveolar component, and increments in the neural–facial ratio and in the respiratory development—seen in their comparisons against Lagoa Santa and Tlatelolco were confirmed. The posteroneural increment seemed to be an exclusive ARTICLE IN PRESS Fig. 3. Inter-populational sD2 distances between Lagoa Santa and Valley samples, based on both major-component volumetric (neuro- cranial and facial) indices, the morphometric neural–facial index, and for the morphometric indices from the minor functional cranial components. Bars above zero: Lagoa Santa greater than Valley. Bars below zero: Valley greater than Lagoa Santa. White bars: non- significant sD2 differences ðp > 0:05Þ: Gray bars: significant sD2 differences ðpo0:05Þ: Black bars: highly significant sD2 differences ðpo0:01Þ: H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132 129 Tlatelolco variation, apparently not connected with an adaptative trend. The second hypothesis had to be rejected, since most of the functional component variability found was more probably explained by directional adaptative trends than by non-directional hazardous differentiations. The Valley–Lagoa Santa differences agreed with the diver- sity found between other Paleoamericans by Powell and Neves (1999), Barrientos et al. (2001), and Jantz and Owsley (2001). The progressive size reduction trend found in Mesoamerica in function of time, agreed with Lahr’s idea of grasilization as an evolutive mechanism in the modern American man (Lahr, 1995). The progres- sive robusticity found for the South-American samples agreed with the same author about an eventual Fuegian retention of ancestral patterns (Lahr, 1996). We did not agree, however, in that grasilization was all that happened in the Americas, since when cranial compo- nents were compared in sequence, several adaptative explanations could be given. ARTICLE IN PRESS Fig. 4. Inter-populational sD2 distances between the South-American samples, based on both major-component volumetric (neurocranial and facial) indices, the morphometric neural–facial index, and for the morphometric indices from the minor functional cranial components. Bars above zero: first sample greater than the second. Bars below zero: second sample greater than the first. White bars: non-significant differences sD2 ðp > 0:05Þ: Gray bars: significant sD2 differences ðpo0:05Þ: Black bars: highly significant sD2 differences ðpo0:01Þ: H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132130 5. Conclusions Rejection of the null hypotheses shows that many non-fortuitous cranial variations actually happened from the early Holocene to modern times in the Americas. A cause–effect relationship between cranial morphology and environment may be evidenced by the Cranial Functional analysis. Since the early American settlement, several selective-adaptative processes— together with migration and genetic drift—would explain some non-detected craniofacial variation of the American Homo sapiens, when classical craniometrical methods were applied. Acknowledgements The authors are grateful to Dr. Mark G. Hubbe for kindly providing us with the Botocudos data; and to Ing. Ernesto A. Calder !on and to Mrs. Mar!ıa C. Mu *ne, ARTICLE IN PRESS Fig. 5. Inter-populational sD2 distances between the Mexico Valley samples, based on both major-component volumetric (neurocranial and facial) indices, the morphometric neural–facial index, and for the morphometric indices from the minor functional cranial components. Bars above zero: first sample greater than the second. Bars below zero: second sample greater than the first. White bars: non-significant sD2 differences Gray instead ðp > 0:05Þ; gray bars: significant sD2 differences ðpo0:05Þ: Black bars: highly significant sD2 differences ðpo0:01Þ: H.M. Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132 131 for their highly valuable help in the technical assistance, and to Mrs. Damiana C. Pucciarelli for the language correction of the manuscript. This study was partially supported by a grant from the Universidad Nacional de La Plata. References Barrientos, G., Pucciarelli, H.M., Politis, G.G., P!erez, S.I., Sardi, M., 2001. 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Pucciarelli et al. / Quaternary International 109–110 (2003) 123–132132 Early peopling and evolutionary diversification in America Introduction Material and methods Results Discussion First hypothesis Second hypothesis Conclusions Acknowledgements References