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Human occupation in South America by 20,000 BC: the Toca da Tira Peia site,
Piauí, Brazil
Christelle Lahaye
a
,
*
, Marion Hernandez
a
, Eric Boëda
b
, Gisele D. Felice
c
,
d
, Niède Guidon
c
, Sirlei Hoeltz
e
,
Antoine Lourdeau
b
,
f
, Marina Pagli
b
, Anne-Marie Pessis
c
,
f
, Michel Rasse
g
, Sibeli Viana
h
a
Université Michel de Montaigne Bordeaux 3, UMR 5060 CNRS eIRAMAT-CRP2A, Institut de Recherche sur les Archéomatériaux, Maison de l’Archéologie, 33607 Pessac, France
b
Université Paris X eNanterre UMR 7041 CNRS ArScAn Anthropologie des Techniques, des Espaces et des Territoires au Pliocène et Pléistocène (AnTET),
Maison de l’Archéologie et de l’Ethnologie, 21 allée de l’Université, 92023 Nanterre Cedex, France
c
Fundação Museu do Homem Americano (FUMDHAM), Brazil
d
Universidade Federal do Vale do São Francisco, Brazil
e
Archaeo ePesquisas Arqueológicas, Brazil
f
Universidade Federal de Pernambuco eDepartamento de Arqueologia, Recife, PE, Brazil
g
Université de Rouen France, France
h
Pontificia Universidade Católica de Goiás/Instituto Goiano de Pré-História e Antropologia, Goiânia, Brazil
article info
Article history:
Received 17 July 2012
Received in revised form
1 February 2013
Accepted 17 February 2013
Keywords:
Optically stimulated luminescence dating
Toca da Tira Peia
Brazil
First peopling in America
Luminescence
abstract
When and how did the first human beings settle in the American continent? Numerous data, from
archaeological researches as well as from palaeogenetics, anthropological and environmental studies,
have led to partially contradictory interpretations in recent years, often because of the lack of a reliable
chronological framework. The present study contributes to the establishment of such a framework using
luminescence techniques to date a Brazilian archaeological site, the Toca da Tira Peia. It constitutes an
exemplary case study: all our observations and measurements tend to prove the good integrity of the site
and the anthropological nature of the artifacts and we are confident in the accuracy of the luminescence
dating results. All these points underline the importance of the Toca da Tira Peia. The results bring new
pieces of evidence of a human presence in the north-east of Brazil as early as 20,000 BC. The Toca da Tira
Peia thus contributes to the rewriting of the history of the peopling of the American continent.
Ó2013 Elsevier Ltd. All rights reserved.
1. Introduction
Understanding the dynamics, knowing the age and the way the
first peopling of America took place is, more than ever, a challenge
for research, and is closely linked with societal issues. Different
theories have been in contradiction for a long time, and the para-
digm of a post-11,500 years BP occupation has remained predom-
inant for a long time. Nevertheless numerous new pieces of data
question the initial acceptance of a theory of a migration from
Siberia to Beringia, and then from the north to the south of the
American continent. Maybe, most of all, these new data question
the values of the terminus post-quem imposed by a chronological
limit fixed to the Last Glacial Maximum (LGM). As far as the
southern part of the continent is concerned, until recently it was
admitted that it had been quickly colonized after the diffusion of
the Clovis culture in the north.
As already stated there is a lot of data available. However, some
are contradictory and what is needed is reliable chronological
framework. So we propose to bring new chronological data to the
issue by using luminescence dating in the study of a South Amer-
ican archaeological site, the Toca da Tira Peia site, the integrity of
which is not under question. The site is located in Brazil, close to the
Serra da Capivara National Park and its controversial Boqueirão da
Pedra Furada archaeological site. It will contribute to the estab-
lishment of a chronological reference framework, that will allow us
to reconsider the “Clovis first”paradigm and, potentially, to
contribute to the rewriting of the history of the peopling of the
South American continent.
2. State of the art: first peopling in South America
The oldest traces of human activity in the extreme south of the
continent have been studied and the corpus concerning Patagonia
is particularly well documented. The Clovis-first model predicts the
arrival of the Pleistocene hunteregatherers around 10,000 years BP
(around 9500 years BC) in the southern part of the continent. It
*Corresponding author. Tel.: þ33 666862744.
E-mail address: christelle.lahaye@u-bordeaux3.fr (C. Lahaye).
Contents lists available at SciVerse ScienceDirect
Journal of Archaeological Science
journal homepage: http://www.elsevier.com/locate/jas
0305-4403/$ esee front matter Ó2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jas.2013.02.019
Journal of Archaeological Science 40 (2013) 2840e2847
must be pointed out that, throughout this paper, we prefer to
reason in terms of calendar ages, that is to say for radiocarbon ages
with calibrated ages (by the INTCAL09 curve, Reimer et al., 2009), in
order to be able to compare numerical values that are comparable.
In fact the apparent radiocarbon ages (or conventional radiocarbon
ages) are not directly comparable one with another because of the
past variations in the C14 production in the high atmosphere.
Dickinson (2011) reports for example that an interval of 250 years,
between 12,600 and 12,350 years C14 BP, corresponds to 700 cal-
endar years after calibration, while the same interval, between
10,950 and 10,700 years C14 BP, corresponds to an interval of only
100 calendar years after calibration. In order to avoid any confusion,
the different ages cited in the rest of the text will always refer to
calendar years. Moreover, we have chosen for this study to use the
Gregorian calendar to express the calendar ages. In fact it appeared
to us to be useless to complicate the chronological situation by
referring to radiocarbon ages as “before 1950”, or those obtained by
luminescence dating methods as “Before 2000”or “B2k”(Duller,
2011) since, in both cases, it is only a shift with respect to the
year 1 (1950 and 2000 being in fact dates that refer to the Gregorian
calendar). For more clarity and simplicity we have thus chosen to
express all the chronological data as dates AD or BC.
Within the last ten years in particular, new discoveries made in
Patagonia and in the rest of South America have constituted
anomalies with respect to the model. Sites like Monte Verde
(Dillehay, 1989), Tres Arroyos (Steele and Politis, 2009), Cueva Lago
Sofia I, Cerro Tres Tetas Cueva I and Piedra Museo question the
model (Miotti, 2003) since they differ significantly from the North
American Clovis sites by their function, but also by the faunistic
species associated with them, the differences in the availability of
raw material and of course by the taphonomic history of each site,
in addition to the fact that they have radiocarbon ages which are
contemporary, and sometimes older. The location of the sites is
presented on the map in Fig. 1.
One of the elements that led to break the consensus around the
Clovis-first paradigm is the discovery and the dating of the Monte
Verde site, south of Chile. In fact the Monte Verde I site is largely
accepted as being a proof of pre-Clovis occupation, dated to 12,400
years BC. The Monte Verde II, being 20,000 years older, remains the
subject of controversy (see Dillehay, 1989 for the results, and Fiedel,
1999 for the questioning of the results). Some other sites have been
the subject of controversy, which is more or less justified, and
which finally throws the same veil of suspicion over any discovery
older than the LGM. The Boqueirão da Pedra Furada, Piauí state,
Brazil, has shown a sequence of meters of thickness (Guidon, 1989)
and dates, thanks to radiocarbon on charcoal (Guidon and Delibrias,
1986) and thermoluminescence on heated pebbles (Valladas et al.,
2003) from 15,000 to 100,000 years BC. These results have been
criticized because of the proximity between the archaeological site
and the rock, constituted at its upper part by a sedimentary rock
that presents big pebbles similar to the ones found in the archae-
ological levels. The opponents to the possibility of an old human
occupation in the southern part of the continent argued that the
lithic assemblage is constituted by geofacts made by the pebbles
falling on one another, and they refuse any anthropic characteristic
to the lithic artefacts found on the site. The TaimaeTaima site in
Venezuela, dated as 16,000e15,000 BC (Bryan, 1973) is also con-
tested but for stratigraphical reasons (Miotti, 2003). Other sites
spread all over the sub-continent, the occupation of which could be
very old, have been excavated and soon after were criticized, for
example El Abra Rockshelter in Colombia, dated around 12,860e
12,190 years BC (Bryan, 1973), Cerro Tres Tetas Cueva in Argentina
(Paunero, 1993e94,1996) dated around 10,970e10,870 BC and
11,150e10,960 BC (Steele and Politis, 2009), and finally the Casa del
Minero, Fell’s Cave, Quebrada Jaguay, Quebrada Santa Julia, Pedra
Pintada, Piedra Museo, Guitarrero Cave, Los Toldos Cueva 3,
Pikimachay-Flea Cave, Santa Elina, Lapa do Boquete sites.The
chronology of these sites, even if sometimes questioned by some
authors, is presented in Fig. 2. It clearly appears that a great number
of evidences are in contradiction with an acceptation without
conditions of the Clovis-first model.
3. The Toca da Tira Peia rockshelter
3.1. Presentation
The Toca da Tira Peia site is located in Coronel Jose Dias, in the
state of Piauí (north east of Brazil), next to the “Serra da Capivara
National Park”. It is situated in the calcareous massif of Antero. The
site was named in 2008 after the small snake discovered in the
morning lying in the first excavation hole. The site was excavated in
2008 and immediately became the object of great interest. Three
archaeological test pits were excavated, over a 20 m wide zone
Fig. 1. Map of South America, showing the main archaeological sites cited in the
present paper. Most of them have been studied and dated, and question the Clovis first
model.
Fig. 2. Chronology of the cited dated archaeological sites from South America. PF
stands for Pedra Furada phases. The “ice free corridor open”period is indicated, on the
lower part of the graph. Note that the time axis has been interrupted, the oldest dates
reported in PF I being much older than all the other (>70 kyears BC).
C. Lahaye et al. / Journal of Archaeological Science 40 (2013) 2840e2847 2841
immediately below the calcareous rockshelter (Fig. 3). About
twenty lithic artifacts were first identified and studied, including
flakes and denticulate pebble-tools. A second phase of work, of
extensive archaeological diggings and OSL sampling, was carried
out in 2009. Two other archaeological campaigns were carried out
in 2010 and 2011. Dozens of lithic artifacts were unearthed. We
consider that the anthropic origin of the artifacts is indisputable.
Moreover, the lithic industry is considered to be in its original po-
sition, since the surface condition is fresh and some refittings exist
between the artifacts.
From a stratigraphic point of view, the filling is essentially
constituted of 2.50 m clayey-sandy deposits (at the present state of
digging). These deposits arise mainly by soil erosion of karstic clays
which developed during more humid periods and to which have
been added sands arising from the erosion of nearby sandstones
massifs. These deposits are attached to the calcareous slope of the
Antero massif. Eight levels were distinguished, based on colori-
metric arguments, on the fraction of quartz micro-granules, on the
variations of the percentage of aeolian sands and on variations in
sediment plasticity. C1 is the superficial deposit, linked to the
working of quarry and C2 corresponds to the humic layer of recent
soil, from before the extraction of lime from the quarry. The C3 and
C4 layers, respectively 30 and 50 cm thick, are clayey-sandy. The C5
and C6, around 20 cm thick, differ from the upper layers in color,
which is more brownish, therefore suggesting the possibility of an
eluviation print for C5 at the expense of C6.
The C7 and C8 layers, more than 1.50 m thick, have the same
texture as the previous ones. The C8, which is more clayey, has a
more plastic texture and a darker color. The base of this layer has
not yet been reached.
Throughout the sequence some calcareous blocks which have
come from the rock wall can be observed, varying widely in size.
Some quartz pebbles are present, of which a great number are
burnt, depending on the layer. Neither the sedimentary composi-
tion nor the deposit mode can explain the presence of such pebbles.
From an archaeological point of view (Fig. 4), at least five
archaeological ensembles have been individuated (at the actual
point of the digging operations). Three of them can clearly be
recognized stratigraphically (C4a in the west zone, C6a and C8b in
the east zone) and can be identified culturally. C4a is in the upper
part of C4 layer. One sample has been taken for OSL dating in the C4
layer, but cannot be directly connected with C4a assemblage
because it has been taken from the east part of the site. The artifacts
vertical distribution is low, and in any case is less than 10 cm. The
refittings of several horizontal artifacts confirm this observation.
The lithic material of the second archaeological ensemble, C6a
(Fig. 5), is located in the upper part of C6. Three refittings show a
perfect horizontality. An OSL tube has been sampled in the
archaeological layer. The third ensemble, C7a (Fig. 3), is lying under
C6a by a few centimeters. It contains some artifacts and homoge-
nous quartz pebble, some of them presenting traces of bipolar
impacts, and some others being burnt. An OSL sample has been
taken directly in the archaeological layer. The fourth ensemble, C8a,
is in the upper part of C8 and contains less than a dozen of artifacts.
It is completely horizontal, as confirmed by a refitting. No sediment
has been sampled in the layer for the moment, because at the time
of OSL sampling this layer had not been reached. Finally the fifth
archaeological ensemble, C8b, is situated about 20 cm under the
previous one. Few artifacts have been unearthed, but those that
have present the same horizontality. It should be noted that both
these archaeological ensembles are located at the north-west limit
of the digging area.
Numerically, we must specify the quantities of artifacts found at
each level. 113 knapped artifacts have been identified, found in
concentrations (very localized spots): 14 artifacts were unearthed
Fig. 3. The Toca da Tira Peia Rockshelter during the 2008 excavations. The calcareous
rockshelter has approximately an east-west orientation.
Fig. 4. Projection of the artifacts and pebbles of the Tira Peia of the east zone. The C4a
ensemble is not represented because it is situated in the west part of the site.
C. Lahaye et al. / Journal of Archaeological Science 40 (2013) 2840e28472842
in C4, 57 in C6, 6 pieces in C7, 13 in C8 and 2 in C9. 35 of them were
interpreted as tools, 12 are cores and 67 are flakes. The other arti-
facts (small pieces) cannot be localized precisely because they were
found in the sieve.
3.2. Why did we choose to study the Toca da Tira Peia
archaeological site?
The reasons why we chose to study the Toca da Tira Peia are
clear. Seeing that the scientific community has rejected some site
for varying reasons we decided to select the sites for study very
rigorously in order to bring new chronological data to the argu-
ment. Besides the imperative quality and reliability of the dating,
conditions that can be satisfied by optically stimulated lumines-
cence (OSL) dating techniques (Aitken, 1998;Wintle, 2008), it also
appeared to be very important to study archaeological sites where
the human occupation is not in doubt. It is also necessary to
ensure the reliability of the data that can be deduced, particularly
by verifying the absence of strong taphonomic problems and
verifying that no mixing between the levels can be suspected. The
Toca da Tira Peia archaeological site fits these requirements. First
of all it is a very interesting site from an archaeological point of
view. Dozens of artifacts were unearthed on this site, which
doesn’t run the risk of facing the same criticism as that addressed
to the Boqueirão da Pedra Furada site, since there are no pebbles
in the summit of the cliff, and very few other pebbles in the
sediment, so we deduced that the pebbles were brought and
knapped by human beings. Moreover from geologic and geo-
morphologic studies, the deposit modes of the sediments seem to
be suitable for OSL dating. Finally the artifacts are in their original
position; they had not been subject to movements since their
burial. Dating the sediments by OSL techniques allows the dating
of the deposit of the artifacts.
4. Sampling strategy and preparation
Four levels were sampled during the 2009 excavations. PVC
tubes were sunk in the exposed stratigraphic profiles; their di-
mensions were 3 cm in diameter and 12 cm in depth. Their location
can be seen in Fig. 6. Sample BR 15 corresponds tothe layer C7, BR16
to C6, BR17 to C5 and finally BR18 to C4.
Back at Bordeaux University, laser grain sizes were analyzed in
order to determine the granulometric profile of each sediment
sample. Sieving under a water flow allowed us to select the 20e
41
m
m fraction, which was the dominant fraction in each case.
The selected grain fraction was then submitted to the usual
chemical treatments: HCl to remove carbonates, H
2
O
2
to remove
organic elements, 1 week in H
2
SiF
6
to remove eventual feldspars,
HCl again to remove fluorine that had possibly formed (from H
2
SiF
6
and carbonates) and finally H
2
O rinsing and a last sieving. The
quartz fraction thus obtained was mounted on stainless steel discs
(9.8 mm in diameter) covered with a thin film of silicon oil.
In a first series of measurements we chose to use “large ali-
quots”, each quartz grain deposit being 6 mm in diameter and
containing thousands of grains. A second batch of discs was made
for BR 16 and BR 17 samples, a 1 mm mask being used when
spreading the oil: this second batch of discs constituted a “small
aliquots”group for each sample.
In each case the first measurements that were performed con-
sisted in IRSL measurements to check the absence of feldspars
(Duller, 2003). Equivalent doses were obtained thanks to OSL single
aliquot measurements. It was performed with a Daybreak2200 OSL
reader (Bortolot, 2000), equipped with a calibrated
90
Sr/
90
Y beta
source delivering, at the time of measurements, 7.1 Gy/min to
quartz. Green LEDs (Nichia NSPG310) emitting at 515 nm and
providing a maximum power of 30 mW/cm
2
onto the measured
disc were used for stimulation of the quartz grains. An Electron
Fig. 5. Lithic artifacts from Toca da Tira Peia. a) Artifacts on quartzite pebbles from level C4. b) Up: layer C6a convergent retouched edges tool on quartzite pebble. Down: layer C6a
denticulate tool on siliceous limestone flake (retouched on lower face). c) Artifacts on quartzite pebble from the C7a layer. Up: Bifacially shaped tool.
C. Lahaye et al. / Journal of Archaeological Science 40 (2013) 2840e2847 2843
Tubes 9235 photomultiplier tube measured the signal, after selec-
tion with a set of optical filters (7.5 mm of U-340).
5. Measurements
The basics and principles of luminescence dating in general and
OSL dating in particular have been widely developed elsewhere
(Aitken, 1985,1998;Wintle, 2008). We will just recall that OSL
dating requires the determination of two data: the equivalent dose
and the annual dose. The measurements were performed in the
IRAMAT-CRP2A laboratory, where researches on luminescence
dating have been conducted for more than 40 years. Sample
preparation and measurements were conducted by C. Lahaye and
M. Hernandez.
5.1. Luminescence
In order to adopt the best experimental conditions for each
sample, we first applied recovery tests to bleached aliquots, using a
SAR protocol. The aliquots were first bleached in a solar simulator
for a couple of hours, and then a beta dose (chosen to be of the
order of magnitude of the ED value, approximately measured with
three aliquots for each sample, that is to say 30 Gy for BR18, 50 Gy
for BR17, 60 Gy for BR16 and 70 Gy for BR15) was given to each
aliquot to simulate natural irradiation. The conditions (temperature
and duration of the pre-heat for natural dose and regenerated dose
on one hand, temperature and duration of the pre-heat adminis-
trated to the test dose on the other hand) were accepted as being
good measurement conditions when the three analyzed discs
showed a recovery ratio between 0.95 and 1.05; that is to say when
all the three tested discs gave a ratio of calculated dose to given
dose equal to unity to within about 5%. The results of the tests are
shown in Table S1. The chosen conditions, leading to good recovery
ratios, are also given in Table S2.
The protocol mainly adopted for multi-grain single-aliquot
regenerative doses (SAR) measurements was chosen (Murray and
Wintle, 2000,2003;Wintle and Murray, 2006). Linearly-modu-
lated OSL signals showed that for all the samples, the signal was
dominated by the fast component (Bailey et al., 1997;Jain et al.,
2003). The SAR protocol was applied with the conditions deter-
mined as mentioned above. It led to recycling ratios close to unity
and a recuperation signal ratio of less than 0.5%. Fig. 7 shows the
radial plots obtained for the ED values for the four samples BR15,
BR16, BR17 and BR18, for the first batch of discs, that is to say “large
aliquots”of 6 mm in diameter. This kind of graphical representa-
tion, inherited from fission track analysis, is now largely used in
luminescence dating. It allows us to simultaneously show three
important data: the equivalent dose for each disc, the associated
relative uncertainty, and the degree of concordance between ages
of differing precision. The four radial plots show the same tendency
for the four levels of sediments. In fact we can see in each case that
the points are centered at a medium dose: only one population
appears in all four cases, we cannot assume any mixing of different
populations with different bleaching level (Galbraith et al., 1999).
Moreover, we can observe that the results have a good degree of
precision: in fact the huge majority of the points are on the right
side of the radial plot, showing relative errors of <5%. But the radial
plots of the log palaeodose estimates indicate they are not
Fig. 5. (continued).
C. Lahaye et al. / Journal of Archaeological Science 40 (2013) 2840e28472844
consistent with a common value (that is to say they are not all in the
central band of 2 units on the y-axis, centered at the mean
measured dose). These considerations thus allowed us to choose
the Central Age Model as being the best adapted model for our four
samples (Galbraith et al., 1999): in fact this model takes into ac-
count an adjunct variation of the values around the true value. This
variation can also be measured and is called “over-dispersion”. This
value (OD) expresses the dispersion between the values of ED that
cannot be explained by the statistical variability. The higher the OD,
the more important the processes that have to be taken into ac-
count (mixing of grains from different levels, bad bleaching or
heterogeneity of the bleaching between the grains.). For all the
samples the over-dispersion (OD) values are very small (Table 1)
ranging between 4.7% and 6.4%.
In order to ensure that this low dispersion was not due to the
averaging effect of the several grains measured per aliquot, we
undertook measurements of small aliquots to ensure the absence of
badly bleached grains. To perform this test we prepared and
measured small aliquots of two of the four samples (BR 16 and BR
17). The results are presented in Inline Supplementary Fig. S1. It
clearly shows that there is only one component in the signal. It
confirms that all the measured grains were well bleached in the
past, and confirms that we can use the Central Age Model (CAM)
(Galbraith et al., 1999) to determine ED values (Table 1).
Inline Supplementary Fig. S1 can be found online at http://dx.
doi.org/10.1016/j.jas.2013.02.019.
5.2. Dosimetry
The annual dose rate has been measured by a combination of
measurements in situ and in the laboratory. The in situ measure-
ments were performed with a NaI:Tl 2
0
2
0
gamma-spectrometer
(Canberra NaI Inspector). The external dose rate (sum of gamma
and cosmic contributions) are reported in Table S1. The outer parts
of the collected tubes, whose grains were exposed to sunlight
during sampling operations, were used for laboratory radioelement
contents measurements. These outer parts of each sample were
first extracted from the tubes using a saw. The humidity at sampling
time was measured and it reached values of between 3 and 8%. The
Fig. 7. Radial plots of the four samples, measured as “large aliquots”(A: BR18, B:BR17, C: BR16 and D: BR15).
Fig. 6. Sampling strategy: location of the OSL samples and in-situ gamma spectrom-
etry measurements.
C. Lahaye et al. / Journal of Archaeological Science 40 (2013) 2840e2847 2845
dried sediment was then encapsulated in 12 cc plastic boxes and
the radioelements contents were measured with a High Purity
Gamma spectrometer (Guibert and Schvoerer, 1991) (Broad Energy
Germanium Canberra). The measurements were always conducted
after at least 3 weeks, and the plastic boxes were sealed with
paraffin wax, to ensure that the equilibrium was reached between
pre- and post-radon elements. The results are reported in Table S1.
Our team is used to detecting and taking into account any notable
disequilibrium in the uranium series (Guibert et al., 2009;Lahaye
et al., 2012); in this case the values of U(
238
U) and U(
226
Ra) were
determined, thanks to the contents of the elements of respectively
the beginning of the
238
U and
235
U series and the post-
230
Th ra-
dioelements contents. The values are reported in Table S3. A small
discrepancy between the U(
238
U) and U(
226
Ra) values can be
observed; in any case this value of U(
238
U) never differs from the
U(
226
Ra) value of more than 18% of the latest. Since 97% of the U
gamma annual dose is due to U(
226
Ra) radioelements, the small
observed disequilibrium will only influence the value of the annual
dose very slowly. It can thus be ignored. We therefore consider the
U(
226
Ra) as being the true U content. Generally speaking, we can
observe that the contents of K and Th are quite similar from one
sample to another, K varying between w1.4 and w1.7%, and Th
varying between w12.3 and w14.4 ppm. U is more changing,
varying between w4.5 and w7.5 ppm. In all four cases the radio-
elements contents are quite high.
6. OSL ages and discussion
The four OSL samples have been dated. The OSL ages (Fig. 8)are
given in Table 1. Unsurprisingly, they follow the stratigraphic order.
This confirms all our previous observations that led us to consider
that there had not been notable post-depositional events. The OSL
ages obtained refer to the last exposure of the quartz grains of the
sediments to the light, that is to say the deposit of the layers. The
obtained ages range from 20,000 1500 years BC for the C7 level,
to 2000 300 years BC for the C4 level. The lithic artifacts were
found to be numerous in the C6 and C7 layers, that is to say, in
layers both attributed to the Pleistocene (20,000 1500 years BC
and 15,100 1200 years BC). The C5 level is also dated to
10,900 900 years BC. These results are much older than predicted
by the Clovis-first theory. Moreover, the oldest age, obtained for the
deposit of the sediment of C7 layer, gives a terminus post-quem for
the artifacts unearthed in the C8 layer, during the 2011 excavations
(that is to say after the OSL sampling had been done): it means that
this level is older than 20,000 years BC, that is to say men lived and
used quartz and quartzite knapping in this part of the world at least
10,000 years before predicted.
These results have to be compared with other archaeological
layers dated in several South American sites (Fig. 2): the C7a layer
from Toca da Tira Peia appears to be contemporaneous with some
radiocarbon dates obtained in Pikimachay eFlea Cave 4 and with
the older dates of the Pedra Furada III phase.
These results, composed of reliable and precise luminescence
ages, obtained on sediments containing man-made lithic assem-
blages, reinforce the recent results obtained both in South and
North America (Waters et al., 2011), showing that the first settle-
ments of the continent may be older than predicted.
Acknowledgments
We thank the French Ministry of Foreign Affairs (MAE), the
Fundação Museu do Homem Americano eFUMDHAM, the CNPq
(Conselho Nacional de Desenvolvimento Científico e Tecnológico),
the CNRS (Conseil National de la Recherche Scientifique), Bordeaux
3 University, the Aquitaine Region and the IUF (Institut Uni-
versitaire de France) for funding and technical support. The authors
also sincerely thank Norbert Mercier (IRAMAT-CRP2A, UMR 5060)
for advices, help and re-reading of the present work.
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jas.2013.02.019.
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Table 1
Radiometric data and OSL ages of the sediment samples from the Toca da Tira Peia site.
Sample (layer) External dose
rate (mGy/a)
K% (HPGe) U ppm (HPGe) Th ppm (HPGe) Total annual dose
rate (mGy/a)
ED (Gy) O.D. (%) Age (years before
2011)
Date (years BC)
BR18 (C4) 1.34 0.03 1.44 0.02 6.50 0.06 12.34 0.13 3.65 0.08 14.7 0.1 2.5 0.1 4000 300 2000 300
BR17 (C5) 1.60 0.03 1.73 0.02 7.49 0.06 14.38 0.12 4.33 0.09 55.8 0.6 4.6 1.1 12,900 900 10,900 900
BR16 (C6) 1.62 0.03 1.52 0.02 6.14 0.05 13.09 0.11 3.94 0.08 67.3 0.5 1.8 1.6 17,100 1200 15,100 1200
BR15 (C7) 1.59 0.03 1.35 0.02 4.56 0.04 12.42 0.12 3.54 0.07 77.7 0.8 1.0 5.0 22,000 1500 20,000 1500
Fig. 8. The Toca da Tira Peia archaeological sequence and the OSL dating results. The
arrows indicate the refittings.
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