Journal of Archaeological Science 34 (2007) 1649e1658
http://www.elsevier.com/locate/jas
Artificial cranial deformation in South America: a geometric
morphometrics approximation

S. Ivan Perez*

CONICET, División Antropologı́a, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata,
Paseo del Bosque s/n, 1900 La Plata, Argentina

Received 17 August 2006; received in revised form 16 November 2006; accepted 5 December 2006

Abstract

The bioarchaeological record of South America is characterized by the high frequency of individuals with a variety of cranial deformations
concentrated in three areas (North-West, Central-West and South) of this subcontinent. The general purpose of this paper is to study the variation
in artificial cranial deformation in several regions of Central-West and South of South America. Cranial variation related to artificial deformation
of human cranial remains is analyzed by means of geometric morphometrics and multivariate statistic methods. The results of this work show
that there are no large differences in variation among states, chiefdoms and bands of hunter-gatherers. The pattern of variation observed in
cranial deformation among regions can be interpreted principally according to the chronological and spatial distribution of the cranial samples
analyzed.
� 2006 Elsevier Ltd. All rights reserved.

Keywords: Bioarchaeology; Cultural cranial variation; Cluster identification; Semilandmarks
1. Introduction

The practice of altering the normal growth and develop-
ment of the head during the first few years of life through
application of external forces was a widespread cultural
phenomenon in modern humans (Buikstra and Ubelaker,
1994; Dembo and Imbelloni, 1938; Dingwall, 1931; Ubelaker,
1984). This practice, named artificial cranial deformation, can
be intentional (to produce a specific shape), or unintentional
(the by-product of other behavior) (Brothwell, 1981; Ubelaker,
1984). While in the first case the deformation is generally used
as indicative of group identity (Blom, 2005a; Getszten, 1993;
Munizaga, 1992; Torres-Rouff, 2002, 2003), unintentional de-
formation is mainly the consequence of the use of a board or
band to swaddle the infant to the cradle (Brothwell, 1981). De-
spite the differences in degree of intentionality, such activities

* Tel.: þ54 221 425 9819.

E-mail address: iperez@fcnym.unlp.edu.ar
0305-4403/$ - see front matter � 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jas.2006.12.003
result in a modified head shape that is associated with some
cultural practices performed during infancy (Buikstra and
Ubelaker, 1994; Brothwell, 1981; Torres-Rouff, 2003;
Ubelaker, 1984), and therefore carry some social significance
(Torres-Rouff, 2003).

The bioarchaeological record of South America is charac-
terized by the high frequency of individuals with a variety
of cranial deformations (Imbelloni, 1933a) concentrated in
three areas (North-West, Central-West and South) of this
subcontinent (Fig. 1). The classic works of Imbelloni and
co-workers (Bórmida, 1953e54; Dembo and Imbelloni,
1938; Imbelloni, 1933a,b) established that the highest varia-
tion in deformations occurs in the Central-West region, coin-
ciding with the chiefdom and state of agriculturalists and/or
pastoralists from the Andeans (see Raffino, 1988). In particu-
lar, these researchers pointed out that the Tabular erect, Tabu-
lar oblique and Annular types (in the classification of Dembo
and Imbelloni (1938) as well as their varieties (e.g. Annular
erect and oblique) occur in this area (Blom, 2005a; Dembo
and Imbelloni, 1938; Imbelloni, 1933a,b; Munizaga, 1992;

mailto:iperez@fcnym.unlp.edu.ar
http://http://www.elsevier.com/locate/jas


1650 S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
Torres-Rouff, 2002, 2003; Weiss, 1962). In contrast, the bands
of hunter-gatherers from the Southern region (i.e. Pampa and
Patagonia; see Borrero, 1999, 2001; Orquera, 1987; Politis
and Madrid, 2001) have been characterized by low variability
of cranial deformations, with all of them considered unin-
tentional (Bórmida, 1953e54; Imbelloni, 1924e25, 1933a).
The different deformations found in this area were considered
varieties of the Tabular erect type (Bórmida, 1953e54; Dembo
and Imbelloni, 1938) generated by swaddling the infant to the
cradle (although this idea was discussed more recently by
Mendonça et al., 1988e89).

The analysis of the variation in artificial cranial deforma-
tion was a relevant issue of earlier anthropological work. In
the late nineteenth and early twentieth centuries numerous
studies were carried out to construct classifications of cranial
deformation (e.g. Broca, 1878, 1879; Dembo and Imbelloni,
1938; Gosse, 1855, 1861; Hrdlicka, 1912; Imbelloni, 1924e25;
Neuman, 1942; Topinard, 1879). These traditional classifica-
tions were produced mainly by pooling crania that presented
similarities in external vault morphology (Imbelloni, 1924e
25, 1933b) and using a typological (Hull, 1992; Hunt,
1981; Sober, 1992) approach. This procedure is subject to
significant observer error, and it has limited capacity for

Fig. 1. Geographical distribution of cranial deformations in South America

(gray shading; modified after Imbelloni, 1933a) and samples analyzed in

this work (abbreviations as in Table 1).
the study of morphological variation. In the first half of the
twentieth century, morphometric procedures were developed
(based in planes, lineal measurement and angles), along
with new classifications based on inferring the cause of de-
formation (e.g. Dembo and Imbelloni, 1938; Imbelloni,
1924e25). In addition to building classifications, the early
studies were focused in the use of cranial deformation as cul-
tural trait in the analysis of ethnographic and prehistoric
groups (Bórmida, 1953e54; Imbelloni, 1924e25, 1933a,b;
Weiss, 1962, among others), as well as in the influence of
cranial deformation on racial classifications (Bórmida,
1953e54; Dembo and Imbelloni, 1938). Likewise, more re-
cent studies have been mainly interested in both the effects
of cranial vault deformation on craniofacial growth and de-
velopment (e.g. Antón, 1989; Antón and Weinstein, 1999;
Cheverud et al., 1979, 1992; Corruccini, 1976; Friess and
Baylac, 2003; Kohn et al., 1993; Konigsberg et al., 1993;
Richtsmeier et al., 1984), and the use of deformation as in-
dicative of group identity (e.g. Blom, 2005a; Munizaga,
1992; Torres-Rouff, 2002, 2003). However, although new
and more comprehensive morphometric approximations
have been applied, in particular to the study of the effects
of cranial deformation over craniofacial anatomy (e.g.
Cheverud et al., 1992; Friess and Baylac, 2003; Kohn
et al., 1993), the analyses in these studies have been based
on the traditional classification. In like manner, the recent
investigations on artificial cranial deformation in the Central-
West region of South America from a bioarchaeological
perspective (e.g. Blom, 2005a,b; Munizaga, 1992; O’Brien,
2003; O’Brien and Sanzetenea, 2002; Torres-Rouff, 2002,
2003) has been addressed from a typological perspective,
using the traditional classification (e.g. Dembo and Imbelloni,
1938; Imbelloni, 1924e25; Steward, 1973) to examine broad
regional differences.

The general goal of this paper is to study the variation in
artificial cranial deformation in several regions of Central-
Western and Southern South America (Fig. 1). This work
aims specifically at: (a) analyzing vault variation generated
by cultural factors in samples that represent prehistoric popu-
lations of band of hunter-gatherers and chiefdoms and state of
agriculturalists and/or pastoralists; (b) grouping individuals
with similar culturally modified vault morphology within
each sample; and (c) comparing cultural variation among sam-
ples. Cranial variation related to artificial deformation of hu-
man cranial remains will be analyzed by means of geometric
morphometrics (Adams et al., 2004; Marcus, 1990; Rohlf,
1990; Rohlf and Marcus, 1993) and multivariate statistical
methods. The fundamental advantage of geometric morpho-
metrics over traditional approaches (Marcus, 1990; Reyment
et al., 1984) is in the development of powerful statistical
methods based on models for shape variation of an entire con-
figuration of points corresponding to the locations of morpho-
logical landmarks (Bookstein, 1991; Rohlf, 1999, 2000) and
semilandmarks (Bookstein, 1997). Thus, it will be possible
to contrast previous studies dealing with the variation of cra-
nial deformations in broad regional scale with a new, more
objective and powerful procedure.



1651S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
2. Materials and methods

The samples of human remains included in this study cor-
respond to adult (ca. 18 to 45 years) male and female individ-
uals from several South American regions (Fig. 1, Table 1).
Sex and age estimation were made on the basis of cranial
and pelvic features (Buikstra and Ubelaker, 1994). The sam-
ples analyzed belong to late Holocene prehistoric populations
with differences in subsistence modes, hierarchy and social or-
ganization (Table 1). While the groups from Andes (B, J-S and
NC) are agriculturalists and/or pastoralists with chiefdom or
state organization, the Patagonian (NR, ChR and SP), South
Cuyo (SC) and Chaco (Ch-E) groups are bands of hunter-
gatherers.

For morphometric analyses the individuals were positioned
in the Frankfurt plane and digital images were obtained from
the crania in lateral (left side) norm with an Olympus Camedia
C-3030 digital camera. Coordinates for two landmarks (-)
and 78 semilandmarks (C) were recorded on the lateral
norm of the crania (Fig. 2). Alignment ‘‘fans’’ at equal angular
displacements along a curve were placed using the MakeFan6
software (Sheets, 2003), and the coordinates of landmarks and
semilandmarks were recorded by means of the tpsDIG 1.40
software (Rohlf, 2004).

Two series of observations were performed on a sample of
15 crania selected by means of random numbers from the
División Antropologı́a of the Facultad de Ciencias Natural y
Museo (UNLP) collection, with the purpose of evaluating
intraobserver reliability for recording the coordinates of land-
marks and semilandmarks used in this study. These series of
observations were separated by a 15-day interval. Analysis
of intraclass correlation was performed on these coordinates
to assess the degree of concordance between series (Shrout
and Fleiss, 1979; Zar, 1999).

The effects of location, scaling and orientation in landmark
configurations were removed using Generalized Procrustes
analysis (GPA; Bookstein, 1991; Rohlf and Slice, 1990).
Semilandmarks of the crania in lateral norm were aligned by
means of the sliding semilandmark method proposed by
Bookstein (1997). This operation extends the GPA in order
to slide the semilandmark points along the outline curve until
they match as well as possible the positions of corresponding
points along an outline in a reference specimen (Sheets et al.,
2004). This is done because the curves or contours should be
homologous from subject to subject, whereas their individual
points are not (Bookstein et al., 2002). The remaining variation
among individuals is considered as difference in shape. In this
study we used the Semiland6 software (Sheets, 2003) to align
the semilandmarks along their respective curves, sliding them
along it, in order to minimize the Procrustes distance between
the subject and a reference (Sampson et al., 1996; Sheets
et al., 2004).

Fig. 2. Landmarks (-) and semilandmarks (C) recorded from the craniofa-

cial structure.
Table 1

Samples analyzed

Samples Abbr. N\ N_ Region Years BPa

Bolivia1 B 26 36 Altiplano 500e1000

Jujuy-Salta1,2 J-S 33 35 Tilcara, La Poma and La Paya 500e1000

North Cuyo1,2 NC 18 20 Calingasta, Angualasto,

Pachimoco and Jachal

600e800

South Cuyo3 SC 9 23 Atuel river 350e800

Negro River1,2 NR 58 74 Negro river (nearby to the coast) 350e600

2000e3700b

Chubut River1 ChR 66 78 Chubut river (nearby to the coast) 500e1100

1500e2000b

South Patagonia1,2,4,5,6 SP 25 33 NW of Santa Cruz, Magallanes

and Rı́o Gallegos

350e1100

Chaco-Entre Rı́os1,2 Ch-E 10 17 Formosa, Chaco and Entre Rı́os 200e1000

Total 245 316

1División Antropologı́a, Museo de La Plata (La Plata); 2Museo Etnográfico (Buenos Aires); 3Museo Municipal de San Rafael (Mendoza); 4Instituto de la Patagonia

Austral (Punta Arenas); 5Instituto Nacional de Antropologı́a y Pensamiento Latinoamericano, (Buenos Aires); 6Museo Regional Provincial ‘‘Padre Manuel Jesús

Molina’’ (Rı́o Gallegos).
a Approximate date established in base to radiocarbon dating and contextual information.
b Some areas present two moments with different cranial deformations.



1652 S.I. Perez / Journal of Archaeolog
Shape variation within each sample was evaluated using
Foote’s (1993) disparity measurement. This is defined as mor-
phological disparity D ¼

P
(di

2)/(n � 1) where di represents
the distance of the specimens to the group centroid (Zelditch
et al., 2004). Disparity was measured using DisparityBox6
software (Sheets, 2003), which uses the Partial Procrustes dis-
tance as di measure.

The method of Relative Warps was used for the comparison
of the configurations of landmarks and semilandmarks (Book-
stein, 1991). Relative warps are principal components of the
partial warps plus component uniform vectors (Bookstein,
1991; Rohlf, 1993), and were used to describe the major trends
in shape variation among and within samples. The partial warp
scores are components along the orthogonal eigenvectors of
the bending energy matrix and describe non-affine patterns
of shape difference (Bookstein, 1989, 1991; Rohlf, 1993,
1996), whereas the uniform components describe affine shape
differences (Bookstein, 1996; Rohlf and Bookstein, 2003). An
important aspect of this analysis is that the results of statistical
analysis can be expressed as an intuitive deformation grid di-
agram of each case with respect to the mean form or reference.
The analyses were made using the Relative warps 1.40 soft-
ware (Rohlf, 2004). The value of the alpha parameter was
0 (zero), thus including variation at all scales.

A Kernel analysis (Baxter et al., 1997; Browman and
Foster, 1963; Wand, 1994; Wand and Jones, 1995) was used
to investigate the distribution of the shapes related to cranial
deformation in the morphometric plane generated by the Rel-
ative Warps analysis. This technique provides a smoother rep-
resentation of the data and can be used as an informal kind of
clustering method (Baxter et al., 1997). Kernel analysis was
performed using KernSmooth 2.22 package for R 1.9.1 (Ihaka
and Gentleman, 1996).

Finally, the variation among the consensus (mean shape;
see Bookstein, 1991) of the groups defined by the Relative
Warps and Kernel analyses of each sample was analyzed by
means of Relative Warps analysis. The patterns of ordination
produced by this analysis were compared with the geographic
location of the samples using the Procrustes method (Digby
and Kempton, 1987; Gower, 1971; Peres-Neto and Jackson,
2001). This method scales and rotates the ordinations, using
a minimum squared differences criterion, in order to find an
optimal superimposition that maximizes their fit. The sum of
the squared residuals between configurations in their optimal
superimposition can then be used as a measurement of associ-
ation (Gower, 1971). A permutation procedure (PROTEST;
10,000 permutations) was then used to assess the statistical
significance of the Procrustean fit (Peres-Neto and Jackson,
2001). Procrustes analysis was made using vegan 1.4.4 pack-
age for R 1.9.1 (Ihaka and Gentleman, 1996).

3. Results

The digitization of landmarks and semilandmarks shows
excellent consistency (Fleiss, 1981) between observational
series (ICC ¼ 1.00).
The samples from Bolivia, Jujuy-Salta and Negro River
samples showed the highest values of disparity when within-
sample variation was estimated (Table 2). These values are
two (Jujuy-Salta and Negro River samples) and three (Bolivia
sample) times higher than those for the undeformed sample
(Chaco-Entre Rı́os) and for the samples with deformed and un-
deformed crania from Cuyo, Chubut River and South Patago-
nia (this latter sample presented few cases with evidence of
deformation, most of them coming from the north of Santa
Cruz province, Argentina).

The scores of the two first relative warps of the cranial vault
in lateral norm are illustrated only for male individuals of four
samples (two samples of Andean region and other two samples
of Patagonian region) in Figs. 3 and 4. The results for female
individuals are not presented here, but similar findings were
obtained for both sexes. Interestingly, the patterns of concen-
trations of points were different among the four samples ill-
ustrated (Figs. 3 and 4). Three clearly differentiated sets,
grouping concentration of morphologies, were distinguished
for the Bolivia sample using kernel density contours
(Fig. 3a). The largest group (ND) corresponds to the unde-
formed crania. The grid that corresponds to the first group
interpretable as deformed crania (B1) shows intense compres-
sion in both occipital (around the nuchal crest area) and frontal
regions, as well as expansion in the posterior area of the pari-
etal bones. In contrast, the grid corresponding to the other
group interpretable as deformed crania (B2) presents slight
compression in both the occipital and frontal regions. Clearly
different results are obtained when the deformation of the
Jujuy-Salta sample is analyzed. In this case no clearly diffe-
rentiated groups of concentration of morphologies can be
distinguished using kernel density contours (Fig. 3b). The indi-
viduals that correspond to the undeformed (ND) and deformed
(J-S) crania are not differentiated, presenting a continuous dis-
tribution along the first relative warps. The grids corresponding
to the individuals interpretable as deformed (J-S) present slight
compression in both occipital and frontal regions.

Table 2

Foote’s measurement of within-sample disparity for the regions analyzed

Samples Disparity

Bolivia \ 0.0024

Bolivia _ 0.0027

Jujuy-Salta \ 0.0020

Jujuy-Salta _ 0.0016

North Cuyo \ 0.0013

North Cuyo _ 0.0009

South Cuyo \ 0.0013

South Cuyo _ 0.0011

Negro River \ 0.0018

Negro River _ 0.0018

Chubut River \ 0.0008

Chubut River _ 0.0009

South Patagonia \ 0.0010

South Patagonia _ 0.0011

Chaco-Entre Rı́os \ 0.0010

Chaco-Entre Rı́os _ 0.0009

ical Science 34 (2007) 1649e1658



Fig. 3. Relative Warps and Kernel analyses performed using the Bolivia (a) and Jujuy-Salta (b) male skull samples.

1653S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
Fig. 4 shows the results for two Patagonian samples. Fig. 4a
shows three groups of concentration of cultural morphologies
(NR1, NR2 and NR3) and the undeformed group (ND) for
Negro River sample. These groups are distributed more
continually that the Bolivia sample. The grid corresponding
to the first group interpretable as deformed (NR1) presents
compression in both occipital (around the nuchal crest area)
and frontal regions, as well as slight expansion in the posterior
Fig. 4. Relative Warps and Kernel analyses performed using the Negro River (a) and Chubut River (b) male skull samples.



1654 S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
area of parietal bones. The grid corresponding to the second
group interpretable as deformed (NR2) presents slight com-
pression in both occipital and frontal regions. On the other
hand, the NR3 group presents compression in the lambda
area. Finally, the Kernel analysis does not allow to find
well-defined groups of morphologies within the Chubut River
samples (Fig. 4b). The deformed cases (ChR1 and ChR2) are
distributed around the undeformed morphologies (ND). The
grid corresponding to the individuals interpretable as de-
formed in the negative values of relative warp 1 present slight
compression in the frontal region (ChR1), whereas the individ-
uals interpretable as deformed in the positive values of relative
warp 1 present slight compression in the lambda area (ChR2).

Fig. 5 shows the comparison of the consensus for culturally
generated cranial morphologies for all the samples (the first
two relative warps comprise 88.3% of the total variation
among samples). Fig. 5 shows that the cases with slight com-
pression of the frontal bone only occur in the Chubut River
sample. The samples with compression at the lambda region
are distributed in Central and Northern Patagonia (ChR2 and
NR3) and Southern Cuyo (SC). On the other hand, the cases
with compression in the frontal and occipital regions occur
in the Bolivia, Jujuy-Salta, Negro River and Northern Cuyo
samples. The latter sample presents an intermediate

Fig. 5. Relative Warps analyses performed using the consensus of cranial

deformation groups.
morphology between the fronto-occipital compression and
lambda compression morphologies. The samples from Negro
River and Bolivia show deformations with compression in
both occipital and frontal regions, as well as an expansion in
the posterior area of the parietal bones. Finally, the pattern
of variation in cranial deformations among samples of later
late Holocene is mainly related with their geographic distribu-
tion (Fig. 6). The values of association between these variables
is higher for male samples (correlation-like statistic derived
from the Procrustes fit m12 ¼ 0.88, p ¼ 0.001; Fig. 6a) than
for female samples (m12 ¼ 0.80, p ¼ 0.016; Fig. 6b).

4. Discussion

Artificial cranial deformation has been analyzed mainly by
means of visual and traditional morphometrics (based on linear
measurement and angles) techniques (e.g. Antón, 1989; Blom,
2005a,b; Bórmida, 1953e54; Dembo and Imbelloni, 1938;
Neuman, 1942; O’Brien, 2003; O’Brien and Sanzetenea,
2002; Torres-Rouff, 2002, 2003; Weiss, 1962). Traditional
morphometrics (e.g. Antón, 1989; Antón and Weinstein,
1999; Brown, 1981; Moss, 1958), as well as some earlier geo-
metric morphometrics techniques (i.e. Elliptic Fourier and
Finite Element analyses; e.g. Cheverud et al., 1992; Friess
and Baylac, 2003; Kohn et al., 1993), have been employed
by several researchers for the study of the relationship between
artificial cranial deformation and craniofacial growth and
development. In these works the morphometric information
has been used as dependent variable and traditional classifica-
tions (e.g. Dembo and Imbelloni, 1938; Steward, 1973) have
been employed as the independent variable, without previously
establishing an objective independent grouping. Similarly,
recent analyses of cranial deformation in the context of
bioarchaeological studies have based their assessments upon
visual determination. South American studies have mostly
used the Imbelloni classification (e.g. Blom, 2005a,b;
Munizaga, 1992; O’Brien, 2003; O’Brien and Sanzetenea,
2002; Torres-Rouff, 2002, 2003).

The semilandmarks-based geometric morphometric and
multivariate analyses of cranial vault in the present work
have shown the existence of different cultural morphologies
in South America. These morphologies correspond to lambdic
and antero-posterior compression, as well as antero-posterior
compression plus superior expansion (Figs. 3e5). The results
obtained generally agreement with previous descriptions of
cranial deformations in this geographic area that were made
using morphoscopic techniques (Bórmida, 1953e54; Dembo
and Imbelloni, 1938; Imbelloni, 1924e25). However, some
differences between the results of the present work and previ-
ous ones can be highlighted. In the first place, although the
methods used to deform the human cranium to achieve a partic-
ularly desired shape may be similar within human groups and
very different among them, the final shape of crania may vary
due to other factors, such as osseous remodelation and varia-
tions in the degree and duration of the of the deformation prac-
tice performed on each individual, among others. Likewise,
due to the fact that the degree of standardization of the



1655S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
Fig. 6. Procrustes fit of geographic coordinates (circle) onto the position of female (a) and male (b) cranial deformations on relative warps 1 and 2.
deformation can vary among regions and human groups due to
cultural causes, the ability to measure such differences is rel-
evant for anthropological research. For instance, the differ-
ences observed in the pattern of variation between Bolivia
and Negro River regions can be due to the higher standardiza-
tion of cranial deformation in the former, which could there-
fore be related to social and cultural differences between
regions. These subtle differences in the resultant cranial defor-
mation can only be studied by means of quantitative methods.
In the second place, the recognition of discrete groups with as-
sociated cultural meaning (in the way the cranial deformation
types were traditionally defined) is very subjective and it is
subject to significant observational errors. In some areas there
are clearly differentiated cultural groups (e.g. Bolivia and
Negro river regions) whereas in other areas this differentiation
is not present (e.g. Jujuy-Salta and Chubut river regions). The
use of quantitative methods is a useful approach to control ob-
servational error, reducing the subjectivity of the cranial defor-
mation classification. This work uses some of the possible
approximations; particularly in some samples (e.g. Bolivia
and Negro River) the criterion for establishing groups was
chosen on the basis of sets of the most densely clustered points
in the multivariate space (Baxter et al., 1997), while in other
samples groups were divided by choosing a value along rela-
tive warp 1. However, the delimitation of groups with similar
morphology is not a simple task and the criteria to be applied
require further discussion. Finally, the cultural pattern of var-
iation among regions has not been analyzed satisfactorily in
past studies. The use of quantitative methods in this work al-
lows obtaining a pattern of variation in cultural characteristics
that can be used together with several models of cultural trans-
mission and evolution (Cavalli-Sforza, 2000).

The results of this work show that there are no large dif-
ferences in the variations of artificial cranial deformation in
Central-West and Southern South America among states,
chiefdoms and bands of hunter-gatherers. In particular, al-
though the Bolivian altiplano region shows the greatest varia-
tion in morphologies produced by cultural deformation, it is
similar to the one observed in Negro River region (Table 2).
However, these areas can be distinguished by the fact that
the Bolivian altiplano sample shows more differentiated
groups, whereas the Negro River sample shows a greater num-
ber of less differentiated- groups (Figs. 3a, 4a and 5). On the
other hand, although the samples from Chubut River and
Jujuy-Salta did not show a clear boundary between deformed
and undeformed individuals, the latter shows greater variation
(Figs. 3b and 4b; Table 2). Thus, my results do not support the
view held by Imbelloni and co-workers, which emphasized the
existence of large differences in the variation occurring in
chiefdoms and states with respect to bands of hunter-gatherers
(Bórmida, 1953e54; Imbelloni, 1924e25, 1933a). These in-
vestigators pointed out that the hunter-gatherers from Patago-
nia present only one culturally modified morphology (Tabular
erect) with several variants (plano-lambdic, plano-frontal and
pseudocircular), and that these are only unintentional deforma-
tions derived form using a table or band to swaddle the infant
to the cradle (Bórmida, 1953e54; Imbelloni, 1924e25). The
attribution of low cultural (although not morphological) varia-
tion to Patagonian groups was primarily the result of the eth-
nological concepts extracted from Kulturkreislehre thinking
(see Lowie, 1946).

The pattern of variation in cranial deformation observed
among regions can be interpreted according to the chronolog-
ical and spatial distribution of the cranial samples analyzed.
All the samples from the Andean region belong to the later
late Holocene (ca. 500e1000 years BP), but only the individ-
uals with compression in the lambda region have been dated to
later late Holocene in Patagonia and Southern Cuyo (ca. 350e
1100 years BP; Berón and Baffi, 2003; Perez, 2006). The other
deformations from Patagonia have been radiocarbon-dated to
early late Holocene (ca. 1500e3700 years BP; Berón and
Baffi, 2003; Perez, 2006). Thus, the variation observed within
the Patagonian region is to some extent related with temporal
differences. In contrast, the variation in deformations among
later late Holocene samples is principally related to the geo-
graphic distribution of the samples. The Procrustes analyses
show that the morphometric variation among cranial deforma-
tions is associated with the geographic distance separating
them (Fig. 6). In particular, male samples display higher asso-
ciation than female samples, with females ChR2, NR3 and SC



1656 S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
showing greater difference from NC, J-S and B2 (Fig. 6a) than
the one found among males (Fig. 6b).

The spatial pattern found could be explained by means of
a model of isolation by distance, which has been successfully
applied to other cultural traits (Cavalli-Sforza, 2000). This
mathematical model, originally developed to explain biologi-
cal variation, has three relevant parameters in the case of cul-
tural phenomena; of these, the first two are responsible for the
increase of traits differences: innovation rate (equivalent to
mutation rate in biology), sampling or coping error (equivalent
to genetic drift in biology), as well as the migration rate of the
traits between neighborsdwhich decreases trait differences
(Cavalli-Sforza, 2000). However, this model cannot explain
all the variation observed in later late Holocene, because an
important difference in cranial deformations between neigh-
bors is observed in the Bolivian altiplano (Fig. 6). The pres-
ence of different variety of cultural deformations in this
region has been interpreted as an ethnic marker in this area
(Blom, 2005a). An additional interruption in the geographic
ordination of the samples is observed in the Cuyo region
(Fig. 6). The use of cranial deformation as an ethnic marker
probably takes place also in the early late Holocene of Patago-
nia and nearby areas, where there is archaeological evidence
of an increase of territoriality (Madrid and Barrientos,
2000). The increase of territoriality is concordant with greater
diversity of cranial deformations in Patagonia (ChR1, NR1
and NR2). This diversity contrasts with the homogeneity in
cranial deformation observed in the later late Holocene of
Patagonia (Fig. 5), a period marked by greater cultural ho-
mogeneity in the area, probably caused by the expansion of
North Patagonian populations to nearby regions (Barrientos
and Perez, 2004).

5. Conclusion

The research performed after the works of Imbelloni and
co-workers (Bórmida, 1953e54; Dembo and Imbelloni,
1938; Imbelloni, 1933a) have mainly discussed the presence
or absence of the types defined by these authors in different
areas. This approximation was not particularly useful. The
continuous nature of the morphologies analyzed in some areas,
the different expression of these deformations among regions,
plus the high subjectivity involved in the determination of cra-
nial deformations, make the study of cranial deformation using
morphoscopic and typological approach way too narrow for
a modern anthropological perspective. The application of geo-
metric morphometrics and multivariate techniques provides
a wider approach to analyze the vault variation generated by
cultural factors, cluster individuals with similar culturally
modified vault morphology within each sample, and compare
cultural variation among samples. In particular, the semiland-
marks-based geometric morphometric and multivariate analy-
ses of cranial vault used in the present work allowed to find
subtle differences in the cranial deformation between samples,
as well as to recognize discrete groups of individuals with sim-
ilar deformation in a lesser subjective way that the previous
studies, and then analyze quantitatively cultural patterns of
variation among regions.

The analyzed area, the Central-West and South of South
America, was characterized by a diversity of cranial deforma-
tions. The morphologies found in this area correspond to
lambdic and antero-posterior compression, as well as antero-
posterior compression plus superior expansion. The results
of the present work show that there are no great differences re-
garding the overall variation of artificial cranial deformation
between states-chiefdoms and bands of hunter-gatherers, like
it was pointed out previously (Bórmida, 1953e54; Dembo
and Imbelloni, 1938; Imbelloni, 1933a,b). However, these
areas can be distinguished by the fact that the sample from
the Andeans state (i.e. Bolivian altiplano) show more defined
groups that the Patagonian hunter-gatherers which display an
more homogeneous dispersion on the shape space (i.e. Negro
River). Finally, the pattern of variation in cranial deformation
observed among regions can be interpreted according to the
some chronological differences in the Patagonian samples, to
geographical distribution during the later late Holocene and
to ethnic separation for Bolivia and Cuyo-Patagonian bound-
ary as well.

Acknowledgements

I am sincerely grateful to Valeria Bernal and Paula Gonza-
lez for their comments that greatly improved the quality of the
manuscript. I thank Hector M. Pucciarelli [División Antropo-
logı́a. Facultad de Ciencias Naturales y Museo, La Plata (Ar-
gentina)], Inés Baffi and Leandro Luna [Museo Etnográfico
‘‘J. B. Ambrosetti’’, Buenos Aires (Argentina)], Paula Novel-
lino [Museo Municipal de San Rafael (Mendoza, Argentina)],
Mateo Martinic [Instituto de la Patagonia Austral (Punta
Arenas, Chile)], Rafael Goñi [Instituto Nacional de Antropolo-
gı́a y Pensamiento Latinoamericano (Buenos Aires, Argen-
tina)], and the staff at Museo Regional Provincial ‘‘Padre
Manuel Jesús Molina’’ (Rı́o Gallegos, Argentina) for granting
access to the human skeletal collections under their care. I also
thank to Amelia Barreiro and Cecilia Morgan for help me with
the English version of the manuscript. Marina Perez made the
drawings for Figs. 1 and 2. Grant sponsor: Universidad Nacio-
nal de La Plata. Grant sponsorship: Doctoral Fellowship
Argentina Government (CONICET).

References

Adams, D.C., Rohlf, F.J., Slice, D.E., 2004. Geometric morphometrics: ten

years of progress following the ‘revolution’. Italian Journal of Zoology

71, 5e16.

Antón, S.C., 1989. Intentional cranial vault deformation and induced changes

of the cranial base and face. American Journal of Physical Anthropology

79, 253e267.

Antón, S.C., Weinstein, K.J., 1999. Artificial cranial deformation and fossil

Australians revisited. Journal of Human Evolution 36, 195e209.

Barrientos, G., Perez, S.I., 2004. La expansión y dispersión de poblaciones del

norte de Patagonia durante el Holoceno tardı́o: evidencia arqueológica y

modelo explicativo. In: Civalero, T., Fernández, P., Guraieb, G. (Eds.),

Contra viento y marea. Arqueologı́a de Patagonia, Buenos Aires, pp.

179e195.



1657S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
Baxter, M.J., Beardah, C.C., Wright, R.V.S., 1997. Some archaeological appli-

cations of kernel density estimates. Journal of Archaeological Science 24,

347e354.

Berón, M.A., Baffi, E.I., 2003. Procesos de cambio cultural en los cazadores-

recolectores de la provincia de La Pampa, Argentina. Intersecciones en

Antropologı́a 4, 29e43.

Blom, D.E., 2005a. A bioarchaeological approach to Tiwanaku group dynamics.

In: Reycraft, R. (Ed.), Us and Them: Archaeology and Ethnicity in the An-

des. Cotsen Institute of Archaeology Press, Los Angles CA, pp. 153e182.

Blom, D.E., 2005b. Embodying borders: human body modification and diversity

in Tiwanaku society. Journal of Anthropological Archaeology 24, 1e24.

Bookstein, F.L., 1989. Principal warps: Thin-plate splines and the decomposi-

tion of deformations. IEEE Transactions on Pattern Analysis and Machine

Intelligence 11, 567e585.

Bookstein, F.L., 1991. Morphometric Tools for Landmark Data: Geometry and

Biology. Cambridge University Press, Cambridge.

Bookstein, F.L., 1996. Biometrics, biomathematics and the morphometric syn-

thesis. Bulletin of Mathematical Biology 58, 313e365.

Bookstein, F.L., 1997. Landmark methods for forms without landmarks:

Localizing group differences in outline shape. Medical Image Analysis

1, 225e243.

Bookstein, F.L., Streissguth, A.P., Sampson, P.D., Connor, P.D., Barr, H.M.,

2002. Corpus callosum shape and neuropsychological deficits in adult

males with heavy fetal alcohol exposure. NeuroImage 15, 233e251.

Bórmida, M., 1953e54. Los antiguos patagones. Estudio de craneologı́a, Runa

6 (1e2), 55e96.

Borrero, L.A., 1999. The prehistoric exploration and colonization of Fuego-

Patagonia. Journal of World Archaeology 13 (3), 321e355.

Borrero, L.A., 2001. Ambios, continuidades, discontinuidades: discusiones

sobre arqueologı́a Fuego-Patagónica. In: Berberián, E.E., Nielsen, A.E.

(Eds.), Historia Argentina Prehispánica T. 2. Brujas, Córdoba, pp. 815e838.

Buikstra, J., Ubelaker, D., 1994. Standards for Data Collection From Human

Skeletal Remains. Arkansas Archaeological Survey Research Series 44.

Broca, P., 1878. Sur des crânes et des objets d́industrie provenant des fouilles

de M. Ber à Tiahuanaco (Pérou). B.S.A.P 3-1, 230e235.

Broca, P., 1879. Sur un mode peu connu de déformation toulousaine. B.S.A.P

3-2, 699e701.

Brothwell, D.R., 1981. Digging Up Bones. Cornell University Press, New

York.

Browman, A., Foster, P., 1963. Density based exploration of bivariate data.

Statistics and Computing 3, 171e177.

Brown, P., 1981. Artificial cranial deformation: a component in Pleistocene

Australian Aboriginal crania. Archaeology in Oceania 16, 156e167.

Cavalli-Sforza, L.L., 2000. Genes, Peoples, and Languages. University of Cal-

ifornia Press, London.

Cheverud, J.M., Buikstra, J.E., Twichell, E., 1979. Relationship between non-

metric skeletal traits and cranial size and shape. American Journal of

Physical Anthropology 50, 191e198.

Cheverud, J.M., Kohn, L.P., Konigsberg, L.W., Leigh, S.R., 1992. Effects of

fronto-occipital artificial cranial vault deformation on cranial base and

face. American Journal of Physical Anthropology 88, 323e345.

Corruccini, R.S., 1976. The interaction between nonmetric and metric cranial

variation. American Journal of Physical Anthropology 44, 285e294.

Dembo, A., Imbelloni, J., 1938. Deformaciones Intencionales del Cráneo de

Carácter Étnico. J. Anesi, Buenos Aires.

Digby, P.G.N., Kempton, R.A., 1987. Multivariate Analysis of Ecological

Communities. Chapman and Hall, London.

Dingwall, E.J., 1931. Artificial Cranial Deformation. London.

Fleiss, J.L., 1981. Statistical methods for rates and proportions, second ed.

John Willey, New York.

Friess, M., Baylac, M., 2003. Exploring artificial cranial deformation using

Elliptic Fourier analysis of Procrustes aligned outlines. American Journal

of Physical Anthropology 122, 11e22.

Foote, M., 1993. Contributions of individual taxa to overall morphological

disparity. Paleobiology 19, 403e419.

Getszten, P.C., 1993. An investigation into the practice of cranial deformation

among the pre-Columbian peoples of northern Chile. International Journal

of Osteoarchaeology 3, 87e98.
Gosse, L.A., 1855. Essai sur les déformations artificielles du crâne. Annales

d́Hygiène publique et de Médicine légale 2e3, 317e393.

Gosse, L.A., 1861. Questionnaire relatif aux déformations artificielles du

crâne. B.S.A.P 2, 101e104.

Gower, J.C., 1971. Statistical methods of comparing different multivariate

analyses of the same data. In: Hodson, F.R., Kendall, D.G., Tautu, P.

(Eds.), Mathematics in the Archaeological and Historical Sciences. Edin-

burgh University Press, Edinburgh, pp. 138e149.

Hrdlicka, A., 1912. Artificial deformations of the human skull with special

reference to America. Actas del Congreso Internacional de Americanistas,

147e149.

Hull, D., 1992. The effects of the essentialism on taxonomy. Two thousand

years of stasis. In: Ereshefsky, M. (Ed.), The Units of Evolution.

Essays on the Nature of Species. The MIT Press, Cambridge, MA,

pp. 199e225.

Hunt, E., 1981. The Old Physical Anthropology. American Journal of Physical

Anthropology 56, 339e346.

Ihaka, R., Gentleman, R., 1996. R: a language for data analysis and graphics.

Journal of Computational and Graphics Statistics 5, 299e314.

Imbelloni, J., 1924e25. Deformaciones intencionales del cráneo en Sudamér-

ica; polı́gonos craneanos aberrantes. Revista del Museo de La Plata 28,

329e407.

Imbelloni, J., 1933a. América, cuartel general de las deformaciones. Actas del

XXV Congreso Internacional de Americanistas 1, 59e68.

Imbelloni, J., 1933b. Los pueblos deformadores de los Andes. La deformación

intencional de la cabeza, como arte y como elemento diagnóstico de las

culturas. Anales del Museo de Historia Natural 37, 209e254.

Kohn, L.P., Leigh, S.R., Jacobs, S.C., Cheverud, J.M., 1993. Effects of annular

cranial vault modification on cranial base and face. American Journal of

Physical Anthropology 90, 147e168.

Konigsberg, L.W., Kohn, L.A.P., Cheverud, J.M., 1993. Cranial deformation

and nonmetric trait variation. American Journal of Physical Anthropology

90, 35e48.

Lowie, R., 1946. Historia de la etnologı́a. Fondo de Cultura Económica,

México.

Madrid, P., Barrientos, G., 2000. La estructura del registro arqueológico del

sitio Laguna Tres Reyes 1 (Provincia de Buenos Aires): nuevos datos

para la interpretación del poblamiento humano del Sudeste de la Región

Pampeana a inicios del Holoceno tardı́o. Relaciones de la Sociedad Argen-

tina de Antropologı́a 25, 179e206.

Marcus, L.F., 1990. Traditional morphometrics. In: Rohlf, F.J., Bookstein, F.L.

(Eds.), Proceedings of the Michigan Morphometrics Workshop. Special

Publication Number 2. The University of Michigan Museum of Zoology,

Ann Arbor, MI, pp. 77e122.

Mendonça, O.J., Bordach, M.A., Cignetti, A.N., 1988e89. La deformación

craneana en las Lagunas (Neuquén), Relaciones de la Sociedad. Argentina

de Antropologı́a (NS) 17 (2), 57e73.

Moss, J.L., 1958. The pathogenesis of artificial cranial deformation. American

Journal of Physical Anthropology 16, 269e286.

Munizaga, J.R., 1992. Antropologı́a fı́sica de los Andes del Sur. In:

Meggers, B. (Ed.), Prehistoria Sudamericana. Nuevas Perspectivas. Tarax-

acum, Washington, pp. 65e75.

Neuman, G.K., 1942. Types of artificial cranial deformation in the eastern

United States. American Antiquity 7, 306e310.

O’Brien, T.G., 2003. Cranial microvariatin prehistoric south central andean

populations: an assesment of morphology in the Cochabamba collection,

Bolivia, Ph.D. work, Binghamton University, New York.

O’Brien, T.G., Sanzetenea, R., 2002. Deformación craneana artificial: un estu-

dio de la colección de Ibarra Grasso de Cochabamba, Boletı́n del INIAN

Museo. Serie Arqueológica Boliviana 4 (26).

Orquera, L.A., 1987. Advances in the Archaeology of the Pampa and Patago-

nia. Journal of World Prehistory 1 (4), 333e413.

Perez, S.I., 2006. El poblamiento holocenico del Sudeste de la Región

Pampeana: un estudio de morfometrı́a geométrica craneofacial. Doctoral

Thesis work. Universidad Nacional de La Plata.

Peres-Neto, P.R., Jackson, D.A., 2001. How well do multivariate data sets

match? The advantages of a Procrustean superimposition approach over

the Mantel test. Oecologia 129, 169e178.



1658 S.I. Perez / Journal of Archaeological Science 34 (2007) 1649e1658
Politis, G., Madrid, P., 2001. Arqueologı́a pampeana: estado actual y perspec-

tivas. In: Berberian, E., Nielsen, A. (Eds.), Historia Argentina Prehispán-

ica. Editorial Brujas, Córdoba, pp. 737e814.

Raffino, R., 1988. Poblaciones Indı́genas de la Argentina. Tipográfica Edito-

rial, Buenos Aires.

Reyment, R.A., Blackith, R.E., Campbell, N.A., 1984. In: Multivariate Mor-

phometrics, second ed. Academic Press, New York.

Richtsmeier, J.T., Cheverud, J.M., Buikstra, J.E., 1984. The relationships

between cranial metric and nonmetric traits in the rhesus macaques from

Cayo Santiago. American Journal of Physical Anthropology 64, 213e222.

Rohlf, F.J., 1990. Morphometrics. Annual Review of Ecology and Systematics

21, 299e316.

Rohlf, F.J., 1993. Relative warps analysis and an example of its application to

Mosquito wings. In: Marcus, L.F., Bello, E., Garcı́a-Valdecasas, A. (Eds.),

Contributions to Morphometrics. Monografı́as del Museo Nacional de

Ciencias Naturales, Madrid, pp. 132e159.

Rohlf, F.J., 1996. Mophometric spaces, shape components and the effects of

linear transformations. In: Marcus, L.F., Corti, M., Loy, A., Slice, D.,

Naylor, G. (Eds.), Advances in Morphometrics. Plenum Press, New

York, pp. 117e129.

Rohlf, F.J., 1999. Shape statistics: Procrustes superimpositions and tangent

spaces. Journal of Classification 16, 197e223.

Rohlf, F.J., 2000. Statistical power comparisons among alternative morphomet-

ric methods. American Journal of Physical Anthropology 111, 463e478.

Rohlf, F.J., 2004. TPS Series Software. Available at: http//life.bio.sunysb.edu/

morph/.

Rohlf, F.J., Bookstein, F.L., 2003. Computing the uniform component of shape

variation. Systematic Biology 52, 66e69.

Rohlf, F.J., Marcus, L.F., 1993. A Revolution in morphometrics. Tree 8-4,

129e132.

Rohlf, F.J., Slice, D.E., 1990. Extensions of the Procrustes Method for the

optimal superimposition of landmarks. Systematic Zoology 39, 40e59.

Sampson, P.D., Bookstein, F.L., Sheehan, F.H., Bolson, E.L., 1996. Eigen-

shape analysis of left ventricular outlines from contrast ventriculograms.
In: Marcus, L.F., Corti, M., Loy, A., Naylor, G.J.P., Slice, D.E. (Eds.),

Advances in Morphometrics. Nato ASI Series, Series A Life Science,

vol. 284. Plenum, New York, pp. 131e152.

Sheets, H.D., 2003. IMP Software Series. Available at: http://www.canisiu-

s.edu/wsheets/morphsoft.html/.

Sheets, H.D., Keonho, K., Mitchell, C.E., 2004. A combined landmark and

outline-based approach to ontogenetic shape change in the Ordovician

Trilobite Triarthrus becki. In: Eelewa, A. (Ed.), Applications of Mor-

phometrics in Paleontology and Biology. Springer, New York, pp.

67e81.

Shrout, P.E., Fleiss, J.L., 1979. Intraclass correlations: uses in assessing rater

reliability. Psychological Bulletin 2, 420e428.

Sober, E., 1992. Evolution, population thinking, and essentialism. In:

Ereshefsky, M. (Ed.), The Units of Evolution. Essays on the Nature of

Species. MIT Press, Cambridge, MA, pp. 247e278.

Steward, T.D., 1973. The People of America. Charles Scribner’s Sons, New

York.

Topinard, P., 1879. Des déformations ethniques du crane. R. d’A 2, 496e506.

Torres-Rouff, C., 2002. Cranial vault modification and ethnicity in middle

horizon San Pedro de Atacama, Chile. Current Anthropology 43,

163e171.

Torres-Rouff, C., 2003. Shaping Identity: Cranial Vault Modification in the

Pre-Columbian Andes, Doctoral Thesis work, University of California.

Ubelaker, D., 1984. Human Skeletal Remains. Taraxacum, Washington.

Wand, M.P., 1994. Fast computation of multivariate kernel estimators. Journal

of Computational and Graphical Statistics 3, 433e445.

Wand, M.P., Jones, M.C., 1995. Kernel Smoothing. Chapman and Hall,

London.

Weiss, P., 1962. Tipologı́a de las deformaciones cefálicas de los antiguos

peruanos, según la osteologı́a cultural. Revista del Museo Nacional 31,

15e42.

Zar, J.H., 1999. Biostatistical Análisis. Prentice Hall.

Zelditch, M.L., Swiderski, D.L., Sheets, H.D., Fink, W.L., 2004. Geometric

Morphometric for Biologists: A Primer. Academic Press, London.

http://www.canisius.edu/wsheets/morphsoft.html/
http://www.canisius.edu/wsheets/morphsoft.html/

	Artificial cranial deformation in South America: a geometric morphometrics approximation
	Introduction
	Materials and methods
	Results
	Discussion
	Conclusion
	Acknowledgements
	References