Upload
wits
View
1
Download
0
Embed Size (px)
Citation preview
ASSESSING THE ACCIDENTAL VERSUS DELIBERATECOLOUR MODIFICATION OF SHELL BEADS: A CASE STUDYON PERFORATED NASSARIUS KRAUSSIANUS FROM BLOMBOS
CAVE MIDDLE STONE AGE LEVELS*
F. D’ERRICO,1,2† M. VANHAEREN,1 K. VAN NIEKERK,2 C. S. HENSHILWOOD2,3 andR. M. ERASMUS4
1Université de Bordeaux, UMR 5199 PACEA, Equipe Préhistoire, Paléoenvironnement, Patrimoine,33405 Talence cedex, France
2Institute for Archaeology, History, Cultural and Religious Studies, University of Bergen, Øysteinsgate 3, 5007,Bergen, Norway
3Institute for Human Evolution, University of the Witwatersrand, Johannesburg, South Africa4School of Physics, University of the Witwatersrand, Johannesburg, South Africa
Colour plays an eminent role in beadwork. Colour modifications are reported on early shellbeads from Middle Stone Age sites. However, identifying the colouring agent and demonstrat-ing the intentional nature of the colouring process is not straightforward. Here, we provideanalytical data on colour and structural modifications observed on Nassarius kraussianus(Nk) collected in modern thanatocoenoses and on shells of the same species experimentallyheated in oxidizing and reductive atmospheres. Comparison with Nk shell beads from the72 ka old Middle Stone Age levels of Blombos Cave, South Africa, and contextual analysis ofother malacological remains from the same levels that were not used as ornaments identify themechanisms responsible for the change of colour in modern Nk thanatocoenoses and heatedshells, and show that although some Nk shell beads were heated, intentional heat treatment ofshell beads is not demonstrated.
KEYWORDS: ORNAMENTS, BEADWORK, SYMBOLISM, STILL BAY, HEAT TREATMENT,SEM–EDS, RAMAN, MICROSCOPY
INTRODUCTION
The earliest known evidence for the use of personal ornaments consists of perforated marine andestuarine shells found at sites from northern and southern Africa, as well as western Asia, datedto between 100 and 70 ka (Henshilwood et al. 2004; d’Errico et al. 2005, 2008, 2009; Vanhaerenet al. 2006, 2013; Bouzouggar et al. 2007; Bar-Yosef Mayer et al. 2009; Eiwanger et al. 2009).A characteristic trait of these ornaments is that they belong, at each site, to a single species(d’Errico and Vanhaeren 2009). This personal ornament tradition apparently disappears at the endof the last interglacial (c.70 ka). Around 44 ka, beads reappear almost simultaneously in Africaand Eurasia. In Africa, they take the form of ostrich eggshell beads (OESB) (Ambrose 1998;d’Errico et al. 2012; Gliganic et al. 2012); and in Eurasia, of dozens of discrete types identifyingregional patterns (Vanhaeren and d’Errico 2006).
Personal ornaments represent a behaviour specific to humans in which items are displayed onthe physical body to project meaning that can be interpreted by members of the same and possibly
*Received 13 August 2013; accepted 10 October 2013†Corresponding author: email [email protected]
bs_bs_banner
Archaeometry ••, •• (2013) ••–•• doi: 10.1111/arcm.12072
© 2013 University of Oxford
other groups. For this reason, early instances of bead use are commonly interpreted as evidencefor the existence of symbolic communication systems created by human societies comparableto ours (Ambrose 1998; McBrearty and Brooks 2000; Vanhaeren and d’Errico 2006; Kuhn andStiner 2007; Henshilwood and Dubreuil 2011). This argument is not universally accepted andit has been argued that due to their apparent simplicity, the earliest beads do not necessarilyreflect symbolic systems and a degree of cognitive sophistication qualitatively comparable tothose recorded in present-day and historically known human societies (Wynn and Coolidge2007; Botha 2008; Klein 2008; Dissanayake 2009; Coolidge and Overmann 2012; Klein andSteele 2013). The first beadworks may, however, be more complex than one could at first sightbelieve. Bead type is but one factor that plays a role in beadwork codes. Bead size, number,arrangement, colour and location on the body may convey meaning as much as bead type, andthese elements have only recently started to be investigated in the earliest beads. Experimentalreproduction of use wear recorded on Nassarius kraussianus shell beads from Blombos Cavehas recently shown that a clear change in the way of stringing beads and the visual appearanceof the resulting beadwork occurred between the lower and upper Still Bay layers (Vanhaerenet al. 2013). Also, the presence of pigment residues (Henshilwood et al. 2004; d’Errico et al.2005, 2008, 2009; Vanhaeren et al. 2006, 2013; Bouzouggar et al. 2007; Bar-Yosef Mayer et al.2009; Eiwanger et al. 2009) on many well-preserved shell beads from Middle Stone Age(MSA) and Middle Palaeolithic (MP) sites suggests that colour may have played a role in theway early beadworks conveyed meaning. Dark grey to black colouring, interpreted as due toheating, has been observed on marine shell beads from the MSA at Blombos Cave (d’Erricoet al. 2005) and Sibudu (d’Errico et al. 2008) in South Africa, the MP at Grotte des Pigeons,Rhafas and Ifri n’Ammar in Morocco (Bouzouggar et al. 2007; d’Errico et al. 2009; Nami andMoser 2010), on the ostrich egg shell beads (OESB) from the Early Later Stone Age levels atBorder Cave (d’Errico et al. 2012), the Later Stone Age of Geelbek in South Africa (Kandel andConard 2005) and the shell beads from the Upper Palaeolithic/Mesolithic site of Franchthi Cavein Greece (Lange et al. 2008; Perlès and Vanhaeren 2010). It has been suggested (Kandel andConard 2005; Lange et al. 2008, d’Errico et al. 2009; Perlès and Vanhaeren 2010) that darkbeads were submitted to heat treatment for intentional modification of their colour, possibly toenhance their visual impact or convey meaning through colour codes, similarly to what isknown from present-day beadwork (Schoeman 1983; Wickler and Seibt 1995). The identifica-tion of such technology in the MSA and the MP would come as no surprise. Intentional colourmodification of pigment through heating has been proposed for the MP sites of Qafzeh(Godfrey-Smith and Ilani 2004) and Skhul (d’Errico et al. 2010; Salomon et al. 2012). Heattreatment of silcrete for tool production is attested at Pinnacle Point site PP5/6 as early as164 ka and has been recently identified in the Still Bay levels of Blombos Cave dated to 72 ka(Brown et al. 2009; Mourre et al. 2010; Schmidt et al. 2013). Controlled use of fire was alsoinvolved in the production of adhesive to haft tools in Europe and Africa (Mazza et al. 2006;Wadley et al. 2009; Pawlik and Thissen 2011).
However, the question of whether controlled use of fire was applied to change the colour ofbeads remains open. Burnt or burnt-looking marine shells may result from darkening due todiagenetic processes, accidental burning (loss of shells in an active hearth, hearth affectingpre-deposited sediments containing shells), heating for subsistence activities (cooking of ediblespecies), heat treatment to purposely change the colour of the shells or to facilitate its manufac-ture, waste burning or a combination of these factors (Hartzell 1991; Claassen 1998; Stiner 1999;Kandel and Conard 2005; Lange et al. 2008; d’Errico et al. 2009; Perlès and Vanhaeren 2010).In this study, we analyse light and dark Nassarius kraussianus (Nk) shell beads from the Still Bay
2 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
layers of Blombos Cave, modern dead Nk darkened by taphonomic processes, and modernexperimentally heated shells of the same species in order to reach a better understanding of themechanisms responsible for colour change in shells (Lange et al. 2008; Perlès and Vanhaeren2010), and to establish whether Blombos MSA shell beads were heated, and whether this processwas done deliberately to change their colour.
THE ARCHAEOLOGICAL CONTEXT
Blombos Cave is situated 300 km east of Cape Town (34°25′S, 21°13′E), and 100 m inland fromthe Indian Ocean (Fig. 1 (a)). Excavations conducted since 1991 (Fig. 1 (b)) by one of us (CSH)have identified a stratigraphic sequence (Fig. 1 (c)) with, from the top to the bottom, 80 cm ofLater Stone Age (LSA) deposit, an archaeologically sterile layer of aeolian dune sand, referredto as the BBC Hiatus, and four MSA phases (BBC M1, BBC M2 upper, BBC M2 lower and BBCM3) (Henshilwood et al. 2001a,b, 2011; Jacobs et al. 2003a,b, 2006, 2013; Jacobs 2004;Henshilwood 2008a,b; Henshilwood and Dubreuil 2009, 2011; Villa et al. 2009; Mourre et al.2010; Thompson and Henshilwood 2011). LSA layers have been radiocarbon-dated to c.2 ka bp.Multiple- and single-grain OSL and TL methods have provided dates for the sterile sand layerlying on top of the MSA layers and for each of the MSA phases (Fig. 1 (c)): c.70 ka for the sandlayer, c.78–72 ka for the M1 and upper M2 phase, c.84 ka for the lower M2 phase, andc.100 000 ka for the M3 phase (Jones 2001; Henshilwood et al. 2002, 2011; Jacobs et al. 2003a,b,2006, 2013; Tribolo 2003; Jacobs 2004; Tribolo et al. 2006; Thompson and Henshilwood 2011).Bifacial foliate points typical of the Still Bay technocomplex interpreted as spear points (Villaet al. 2009; Mourre et al. 2010), bone tools including awls and fully shaped spear points(Henshilwood et al. 2001a; d’Errico and Henshilwood 2007) are cultural markers of the M1 andupper M2 phases. The M2 lower phase is a low-intensity occupation in which no Still Baycultural markers are found. Ochre pieces, often with traces of utilization, are present in all MSAlayers and abundant in the M3 phase (Henshilwood et al. 2009). Ochre pieces engraved withgeometric patterns come from the M1, M2 and M3 phases (Henshilwood et al. 2009). Possibleengravings on bone (d’Errico et al. 2001; d’Errico and Henshilwood 2007) consisting of parallelstriations and sets of joining lines also come from the M1 and upper M2 phases.
Sixty-eight Nk shell beads (Fig. 2 and Table 1) were found in the Still Bay layers (Henshilwoodet al. 2004; d’Errico et al. 2005; Vanhaeren et al. 2013). All derive from the M1 phase (layersCA, CB, CC and CD), with the exception of two specimens from the upper M2 phase (layer CF)in an area where slumping of overlaying layers occurred. Fifty-six of the 68 Nk beads publishedso far (Vanhaeren et al. 2013) were found in seven groups (1–7) of 2–24 beads, each group beingrecovered in a single square (1 × 1 m) or in two adjacent sub-squares (50 × 50 cm each) duringa single excavation day (Table 1). This led us to propose that each group was originally part ofa single beadwork item, lost or disposed of during a single event (d’Errico et al. 2005). The 12remaining shell beads are isolated recoveries unearthed in different sub-squares or at differentdates (Table 1).
MATERIALS AND METHODS
To identify possible causes of colour variation in Blombos Nk, two heating experiments wereperformed on Nk collected alive, emptied of their meat and cleaned. In the first experiment, 60shells were equally distributed in 20 porcelain crucibles. In 10 crucibles, shells were sandwichedbetween leaves and humic soil. Shells were placed in the other 10 crucibles without additions.
Accidental versus deliberate colour modification of shell beads 3
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Figure 1 (a) The location of Blombos Cave. (b) A map of the site, with excavated areas indicated in white. (c) The southsection of Blombos Cave, showing layers, phases and available OSL, TL and U/Th age ranges for the MSA (modified afterHenshilwood et al. 2011).
4 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Step heating in a Vecstar furnace used 10 temperature intervals of 100°C, ranging from 100°C to1000°C. One crucible from each group was removed from the furnace at each step after the settemperature was reached for 10 min. In the second experiment, three groups of 10 shells wereheated in the soil underneath an open fireplace for approximately 1 h. Ten shells were stuck intothree capsules of Carpobrotus edulis fruits (South African sour figs), 10 shells wrapped in leaves
Figure 2 Perforated Nassarius kraussianus from the Middle Stone Age Phases M1 and M2 at Blombos Cave. Thenumbers refer to Table 1.
Accidental versus deliberate colour modification of shell beads 5
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Tabl
e1
Con
text
ual
and
desc
ript
ive
data
onN
assa
rius
krau
ssia
nus
shel
lbe
ads
from
the
Mid
dle
Ston
eA
gele
vels
ofB
lom
bos
Cav
e
Num
ber
inF
igur
e2
Dat
eof
exca
vati
onM
SAph
ase
Lev
elSq
uare
and
sub-
squa
reG
roup
Dor
sal
side
colo
urVe
ntra
lsi
deco
lour
Surf
ace
feat
ure*
Bur
nt
102
/02/
1999
M1
CA
AF5
c†
Ora
nge
Lig
htbe
ige
PDD
no2
09/0
2/19
98M
1C
AE
5b1
Bei
geB
eige
Nno
309
/02/
1998
M1
CA
E5b
1L
ight
oran
geB
eige
Nno
409
/02/
1998
M1
CA
E5b
1B
eige
Bei
geN
no5
09/0
2/19
98M
1C
AE
5b1
Bei
geB
eige
Nno
609
/02/
1998
M1
CA
F5a
1O
rang
eB
eige
Nno
709
/02/
1998
M1
CB
AE
51
Dar
kor
ange
Bei
gePD
Dno
809
/02/
1998
M1
CB
AE
51
Ora
nge
Bei
geN
no9
09/0
2/19
98M
1C
BF5
a2
Lig
htor
ange
Bei
geN
no10
09/0
2/19
98M
1C
BF5
a2
Lig
htor
ange
Bei
geN
no11
28/0
1/19
99M
1C
BF6
b†
Dar
kbe
ige
Bei
geN
no12
05/0
2/19
99M
1C
BF6
a†
Dar
kbr
own
Lig
htgr
eyN
yes
1306
/02/
1998
M1
CB
E5b
†L
ight
oran
geB
eige
Nno
1405
/02/
1997
M1
CA
-CC
F3†
Dar
kgr
eyD
ark
grey
HC
,HD
yes
1506
/02/
1997
M1
CA
-CC
E2
†L
ight
oran
geB
eige
PDD
no16
11/1
1/19
97M
1C
A-C
CE
43
Lig
htor
ange
Bei
geN
no17
11/1
1/19
97M
1C
A-C
CE
43
Dar
kgr
eyD
ark
brow
nH
Dye
s18
07/0
2/19
97M
1C
A-C
CE
44
Lig
htbr
own
Lig
htor
ange
Nno
1907
/02/
1997
M1
CA
-CC
E4
4B
eige
Bei
gePD
Dno
2007
/02/
1997
M1
CA
-CC
E4
4B
eige
Bei
gePD
Dno
2107
/02/
1997
M1
CA
-CC
E4
4L
ight
beig
eB
eige
PDD
no22
07/0
2/19
97M
1C
A-C
CE
44
Bei
geB
eige
PDD
no23
07/0
2/19
97M
1C
A-C
CE
44
Lig
htor
ange
Bei
gePD
Dno
2407
/02/
1997
M1
CA
-CC
E4
4L
ight
brow
nB
eige
Nno
2507
/02/
1997
M1
CA
-CC
E4
4L
ight
brow
nB
eige
PDD
no26
07/0
2/19
97M
1C
A-C
CE
44
Lig
htbr
own
Bei
gePD
Dno
2707
/02/
1997
M1
CA
-CC
E4
4B
row
nL
ight
brow
nH
Cye
s28
07/0
2/19
97M
1C
A-C
CE
44
Ora
nge
Bei
geN
no29
07/0
2/19
97M
1C
A-C
CE
44
Bei
geB
eige
PDD
no30
10/0
2/19
97M
1C
A-C
CE
45
Bei
geL
ight
beig
ePD
Dno
3110
/02/
1997
M1
CA
-CC
E4
5B
eige
Bei
gePD
Dno
3210
/02/
1997
M1
CA
-CC
E4
5L
ight
brow
nB
eige
Nno
3310
/02/
1997
M1
CA
-CC
E4
5L
ight
brow
nB
eige
Nno
3410
/02/
1997
M1
CA
-CC
E4
5L
ight
brow
nB
eige
Nno
6 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
3516
/02/
2000
M1
CC
H5a
6D
ark
brow
nB
row
nH
C,H
Dye
s36
16/0
2/20
00M
1C
CH
5a6
Dar
kgr
eyD
ark
grey
HC
,HD
yes
3716
/02/
2000
M1
CC
H5a
6D
ark
grey
Gre
yH
C,H
Dye
s38
16/0
2/20
00M
1C
CH
5a6
Dar
kgr
eyG
rey
HC
yes
3916
/02/
2000
M1
CC
H5c
6D
ark
oran
geO
rang
eH
C,H
Dye
s40
06/0
2/19
98M
2C
FAE
4a†
Bei
geL
ight
beig
eN
no41
09/0
2/19
98M
2C
FE
5b†
Lig
htbr
own
Bei
geN
no42
16/0
2/20
00M
1C
CH
5c6
Dar
kor
ange
Bei
geH
C,H
Dye
s43
16/0
2/20
00M
1C
CH
5c6
Dar
kbr
own
Dar
kbr
own
HC
yes
4416
/02/
2000
M1
CC
H5c
6D
ark
beig
eB
eige
Nno
4516
/02/
2000
M1
CC
H5c
6D
ark
beig
eL
ight
oran
geH
Cye
s46
16/0
2/20
00M
1C
CH
5c6
Ora
nge
Lig
htor
ange
HC
yes
4716
/02/
2000
M1
CC
H5c
6D
ark
brow
nB
row
nH
Cye
s48
16/0
2/20
00M
1C
CH
5c6
Ora
nge
Ora
nge
Nno
4916
/02/
2000
M1
CC
H5c
6D
ark
beig
eB
eige
PDD
no50
16/0
2/20
00M
1C
CH
5c6
Lig
htor
ange
Bei
gePD
Dno
5116
/02/
2000
M1
CC
H5c
6D
ark
beig
eL
ight
oran
gePD
Dno
5216
/02/
2000
M1
CC
H5c
6D
ark
grey
Dar
kgr
eyN
yes
5316
/02/
2000
M1
CC
H5c
6D
ark
grey
Gre
yN
yes
5416
/02/
2000
M1
CC
H5c
6D
ark
grey
Dar
kbr
own
Nye
s55
16/0
2/20
00M
1C
CH
5c6
Ora
nge
Lig
htor
ange
PDD
no56
16/0
2/20
00M
1C
CH
5c6
Dar
kbr
own
Lig
htbr
own
HC
yes
5716
/02/
2000
M1
CC
H5c
6D
ark
brow
nD
ark
brow
nH
Cye
s58
16/0
2/20
00M
1C
CH
5c6
Dar
kbe
ige
Dar
kor
ange
Nye
s59
16/0
2/20
00M
1C
CH
5c6
Ora
nge
Lig
htor
ange
HC
,HD
yes
6016
/02/
2000
M1
CC
H5c
6O
rang
eL
ight
oran
gePD
Dno
6124
/04/
2002
M1
CC
H6b
7B
eige
Ora
nge
PDD
no62
24/0
4/20
02M
1C
CH
6b7
Gre
yB
row
nH
C,H
Dye
s63
24/0
4/20
02M
1C
CH
6b7
Gre
yB
row
nH
C,H
Dye
s64
24/0
4/20
02M
1C
CH
6b7
Dar
kbe
ige
Ora
nge
Nno
6522
/04/
2002
M1
CC
H6b
†L
ight
oran
geO
rang
ePD
Dno
6615
/04/
2004
M1
CC
I5c
†L
ight
oran
geO
rang
eN
no67
17/0
4/20
02M
1C
AH
6b†
Dar
kbr
own
Bro
wn
HC
yes
6820
/04/
2004
M1
CD
h2I5
c†
Bei
geB
eige
HC
,HD
yes
*PD
D,p
ost-
depo
sitio
nal
dam
age;
HC
,hea
tcr
acks
;H
D,d
esqu
amat
ion;
N,n
one.
†Iso
late
dre
cove
ry.
Accidental versus deliberate colour modification of shell beads 7
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
and 10 buried in the soil. The compact sticky flesh of the sour fig presents the advantage ofhomogeneously embedding the Nk shells with organic material, avoiding oxidation during theheating process.
Modern unmodified and experimentally heated specimens were prepared for analysis of theirchemical and microstructural composition as follows: the lateral aspect of the shell opposite tothe lip was abraded with an ESCIL 300 GTL lapping and polishing machine, using an 800 gritpaper, until a 3 × 2 mm perforation was created. The perforation edge was then polished using acloth covered with a fine diamond polishing solution. The resulting surfaces were examined withan optical microscope in reflected light and polishing was repeated until all visible scratches wereremoved. Shells were then etched in a 0.1 M solution of HCl in distilled water for 3 s, rinsed indistilled water and air dried.
Unetched and etched shells were analysed and photographed using a motorized Leica Z6APOA microscope equipped with a DFC420 digital camera and a Leica Application Suiteequipped with the Multifocus Module. To determine their elemental composition, five etchedmodern specimens were analysed using a JEOL 840A scanning electron microscope (SEM)equipped with an energy-dispersive X-ray system (EDAX). The modern shells included oneunheated specimen from the Goukou Estuary biocoenosis, one unheated specimen from athanatocoenosis of the same estuary showing a dark grey colouring, and six more specimens fromthe Goukou biocoenosis: one heated with leaves underneath an open fireplace and five heated ina furnace at temperatures of 400°C, 600°C and 800°C respectively, with leaves and soil, and300°C and 600°C as such.
To determine the structural composition in a non-destructive way, four unetched modern shellsas well as two archaeological Nk—a beige (Table 1, no. 42; Fig. 2, no. 42) and a dark grey(Table 1, no. 53; Fig. 2, no. 53) specimen from the Blombos Still Bay level CC—with fracturesshowing the internal shell structure, were analysed using a Jobin Yvon T64000 Raman spectrom-eter operated in triple subtractive mode. The 514.5 nm line of an argon ion laser was used as theexcitation source. Backscattered spectra were collected via an Olympus BX40 microscopeRaman attachment, and the light dispersed via 1800 lines per millimetre gratings on to a liquidnitrogen–cooled CCD detector. Power for the sample was kept fairly low (1.2 mW) to minimizelocalized heating effects. A narrow bandpass filter was used to remove laser plasma lines from thespectra. The modern shells included one specimen heated within a sour fig beneath an open fire,and three specimens heated in a furnace, two between leaves and humic soil at 400° and 800°Crespectively, the third as such at 300°C.
Three shades of beige, brown, orange and grey were used to account for colour variation on thedorsal and ventral sides of unmodified and experimentally heated modern Nk shells and Nk shellbeads from the MSA levels at Blombos Cave (Vanhaeren et al. 2013). For comparative purposes,colour variation was also recorded on a representative sample of malacofauna, not used asornaments, from the same MSA level (CC) that yielded most of the dark grey Nk shell beads. Thecomparative sample comes from four 50 × 50 cm sub-squares (H5a H5c, H6b and I5c). Thepresence of cracks and desquamations was systematically recorded using a Wild M3C micro-scope equipped with a Coolpix 995 digital camera.
RESULTS
The colour and shade of the Blombos MSA Nk shells varies between beige, orange, brown andgrey, depending on the observed shell aspect (Table 2) and the stratigraphic level in which theshell was found (Table 3). An opposition appears to exist within this variation between shades of
8 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Tabl
e2
The
cont
inge
ncy
tabl
eof
colo
urva
riat
ion
onth
edo
rsal
and
vent
ral
aspe
ctof
Blo
mbo
sM
iddl
eSt
one
Age
Nas
sari
uskr
auss
ianu
ssh
ells
Dor
sal
colo
urVe
ntra
lco
lour
*
L.b
eige
Bei
geD
.bei
geL
.ora
nge
Ora
nge
D.o
rang
eL
.bro
wn
Bro
wn
D.b
row
nL
.gre
yG
rey
D.g
rey
Tota
l
L.b
eige
11
Bei
ge2
101
13D
.bei
ge3
21
17
L.o
rang
e8
19
Ora
nge
13
41
9D
.ora
nge
21
3L
.bro
wn
71
8B
row
n1
1D
.bro
wn
13
21
7L
.gre
y0
Gre
y2
2D
.gre
y2
33
8To
tal
334
07
51
25
41
33
68
*L,l
ight
;D
,dar
k.
Accidental versus deliberate colour modification of shell beads 9
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Tabl
e3
The
freq
uenc
yof
colo
urva
riat
ion
onth
edo
rsal
and
vent
ral
aspe
cts
ofB
lom
bos
Mid
dle
Ston
eA
geN
assa
rius
krau
ssia
nus
shel
lsac
cord
ing
tole
vel
and
spat
ial
grou
ping
Dor
sal
colo
ur*
L.b
eige
Bei
geD
.bei
geL
.ora
nge
Ora
nge
D.o
rang
eL
brow
nB
row
nD
.bro
wn
L.g
rey
Gre
yD
.gre
yTo
tal
Lay
erC
A–
4–
11
––
––
––
–6
CA
A–
––
–1
––
––
––
–1
CB
––
13
––
––
1–
––
5C
BA
––
––
11
––
––
––
2C
C–
16
25
2–
–6
–2
630
CD
h21
––
––
––
––
––
–1
CF
––
––
––
1–
––
––
1C
FA1
––
––
––
––
––
–1
CA
-CC
16
–3
1–
71
––
–2
21To
tal
113
79
93
81
80
28
68
Gro
up1
–3
–1
21
––
––
––
72
––
–2
––
––
––
––
23
––
–1
––
––
––
–1
24
14
–1
1–
41
––
––
125
–2
––
––
3–
––
––
56
––
51
52
–5
––
–6
247
1–
––
––
––
––
2–
3Is
olat
ed–
32
31
–1
–2
––
113
Tota
l1
137
99
38
17
02
868
10 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Vent
ral
colo
ur*
L.b
eige
beig
eD
.bei
geL
.ora
nge
Ora
nge
D.o
rang
eL
brow
nB
row
nD
.bro
wn
L.g
rey
Gre
yD
.gre
yTo
tal
Lay
erC
A–
6–
––
––
––
––
–6
CA
A1
––
––
––
––
––
–1
CB
–4
––
––
––
–1
––
5C
BA
–2
––
––
––
––
––
2C
C–
4–
65
11
53
–3
230
CD
h2–
1–
––
––
––
––
–1
CF
–1
––
––
––
––
––
1C
FA1
––
––
––
––
––
–1
CA
-CC
116
–1
––
1–
1–
–1
21To
tal
334
07
51
25
41
33
68
Gro
up1
–7
––
––
––
––
––
72
–2
––
––
––
––
––
23
–1
––
––
––
1–
––
24
–10
–1
––
1–
––
––
125
14
––
––
––
––
––
56
–4
–6
21
12
3–
32
247
––
––
1–
–2
––
––
3Is
olat
ed2
6–
–2
––
1–
1–
13
Tota
l3
340
75
12
54
13
368
*L,l
ight
;D
,dar
k.
Accidental versus deliberate colour modification of shell beads 11
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
beige, orange and light brown on the one hand and shades of darker brown and grey on the otherhand, as single shells may display various shades within these two broader groups but nevercombine shades from both (Table 2). The largest colour variation is observed on the ventralaspect of Nk shells from layer CC (Table 2). This layer also yielded all the brown- and grey-coloured shells, with the exception of one shell from the intermediate level CB that had a lightgrey ventral and a dark brown dorsal side (Table 2).
Colour variations of this type are not observed on modern Nk collected alive, as these displaya combination of green, khaki and yellow shades (Fig. 3). Shades of beige, orange, brown andgrey are, however, observed in modern Nk thanatocoenoses (Fig. 3). SEM observation andelemental characterization, through energy-dispersive X-ray spectroscopy (EDAX) of a modernshell collected alive and a modern dark grey shell collected dead, indicates that 5–10 μm longparticles of pyrite (iron sulphide), migrating through the more porous dorsal surface, probably as
Figure 3 Colour variation on the dorsal and ventral aspects of Nassarius kraussianus shells collected alive at theDuiwenhoks estuary, Cape Province, South Africa (a), dead at Goukou estuary, Cape Province, South Africa (b), andcollected alive and heated after cleaning them at different temperatures in an oxidizing (c) and reducing atmospherecreated by sealing the shells with organic material (d).
12 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
a result of bacterial activity (Silverman 1967), are responsible for the black colouring of Nk shellsfound in modern thanatocoenoses (Figs 4 and 5).
SEM observation and EDAX analysis did not identify particles of pyrite on MSA Nk shellbeads. In addition, Raman spectroscopy of a dark grey MSA shell did not show any evidence forthe presence of iron sulphide (peaks at 342 and 379 cm−1; McGuire et al. 2001) indicating thatthis diagenetic process is not responsible for the colouring of the MSA shells (Fig. 6).
Experimental heating of modern Nk produced shells that had colours and shades that differedrelative to temperature and atmosphere (Fig. 3). Heating shells in an organic compound within a
Figure 4 A polished and etched section of a dark grey Nassarius kraussianus from a thanatocoenois collected at theGoukou estuary, observed in optical (a) and SEM microscopy (b, c). Note in (a) the presence of black particlespenetrating the shell matrix from the dorsal outer surface, on the left of the photograph, and in (b, c) the sameparticles highlighted by the etching of the shell surface. The arrows indicate the particles analysed by EDAX inFigure 5 (d).
Accidental versus deliberate colour modification of shell beads 13
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
reductive atmosphere resulted in the shell colour changing into dark grey/black at temperaturesabove 300°C and produced a glossy black shell surface at temperatures above 500°C. The coatingof and penetration into the shell of amorphous carbon released by the leaves and humic soil isprobably responsible for the dark-grey/black colouring of the shells at temperatures above 300°C.The glossy metallic appearance of this black coating on shells heated above 500°C can possiblybe explained by structural modification of the layer due to release of O and H, previously reportedto occur between 450°C and 500°C (Ray et al. 2003). Heating in an oxidizing atmosphereproduced larger colour variation. The ventral sides of the shells became light beige, beige, light
Figure 5 SEM–EDAX spectra of the surface of a light-coloured unmodified Nassarius kraussianus (Nk) collected alivein the Duiwenhoks estuary (a), a dark-coloured Nk from the Goukou estuary thanatocoenosis (b), Nk heated at 300°C(c) and 600°C (d) in an oxidizing atmosphere, Nk heated at 400°C (e), 600°C (f) and 800°C (g) in a reducing atmospherecreated by sealing the shells with organic material, and of a Nk heated within the capsule of a South African sour fig inthe soil underneath an open fireplace (h). The peaks of gold, chlorine and sodium are due to etching and metal coatingfor SEM analysis. The aluminium, sulphur and iron peaks in (b) are most probably due to permineralization, replacementand weathering phenomena affecting shells in thanatocoenoses.
14 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Figu
re6
Ram
ansp
ectr
aof
(a)
four
diff
eren
tshe
llla
yers
inm
oder
nun
mod
ified
Nas
sari
uskr
auss
ianu
s(1
,out
ersh
elll
ayer
;2,
3,m
iddl
esh
elll
ayer
s;4a
,4b,
inne
rsh
elll
ayer
);(b
)m
oder
nN
assa
rius
krau
ssia
nus
heat
edat
diff
eren
tte
mpe
ratu
res
inox
idiz
ing
(1,
300°
C,
inne
rsh
ell
laye
r;2,
300°
C,
mid
dle
shel
lla
yer;
3,30
0°C
,ou
ter
shel
lla
yer)
and
redu
cing
atm
osph
eres
(4,4
00°C
,inn
ersh
ell
laye
r;5,
400°
C,o
uter
shel
lla
yer;
6,80
0°C
),(c
)m
oder
nN
assa
rius
krau
ssia
nus
heat
edin
the
soil
unde
rnea
than
open
firep
lace
,an
d(d
:1a
,1b)
ali
ght(
Tabl
e1,
no.4
2)an
d(d
:2a
–c)
dark
(Tab
le1,
no.5
3)co
lour
edN
kfr
omM
iddl
eSt
one
Age
leve
lCC
ofB
lom
bos
Cav
e.T
hepe
aks
corr
espo
ndto
arag
onit
e(a
t20
5cm
−1),
calc
ite
(at
280
cm−1
)an
dca
rote
noid
pigm
ents
(at
1133
and
1526
cm−1
)pr
esen
tin
the
shel
l(U
rmos
etal
.199
1;W
ithn
all
etal
.200
3).
Accidental versus deliberate colour modification of shell beads 15
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Figu
re6
Con
tinu
ed.
16 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
brown, grey and white at 200°C, 300°C, 400°C, 500°C and 800°C respectively. The black colourobserved on the dorsal aspect of shells heated at 300°C to 400°C in an oxidizing atmosphere, andon both shell aspects of shells heated at 400°C to 500°C in a reductive atmosphere, is due to asuperficial layer of soot obscuring the underlying shell colour.
Optical and scanning electron microscopy analysis coupled with EDAX and Raman spec-troscopy shows that heating Nk causes structural modifications. These analyses reveal that Nkshells are composed of four layers of aragonite crystals with a crossed lamellar layered micro-structure (Fig. 6) that degrade into calcite with an irregular prismatic microstructure at tem-peratures above 300°C (Figs 7 and 8). At 800°C in an oxidizing atmosphere, the calciumcarbonate is transformed in calcium oxide (lime), leading to the decomposition of the shell(Fig. 6). At the same temperature in a reducing atmosphere, the calcite undergoes adensification with elimination of porosity and net shrinkage (Fig. 8 (b)). Elemental analysis(Fig. 5) shows that Nk heated in a reducing atmosphere and in the presence of organic materialbecome enriched in carbon, probably in the form of amorphous carbon, which is responsiblefor the blackening of the shells.
Raman analysis shows that dark MSA Nk are composed of calcite and the light-colouredNk, found in the same stratigraphic levels, of aragonite (Fig. 6). The presence of heat crackson the surface of dark MSA Nk (Fig. 9) confirms that they have been heated. On the basis ofthe experimental results presented above, dark MSA Nk shells were heated in a reductiveenvironment at a temperature between 300°C and 500°C, a process responsible for theircolouring.
Burnt marine shells other than Nk do occur in the same sub-squares in which burnt and unburntNk were recovered (Table 4). The proportion of burnt shells increases with their degree offragmentation. The only difference between Nk and edible species is that unlike Nk, the lattersystematically include remains of calcined shells resulting from prolonged heating at hightemperature in an oxidizing environment. Like Nk, inedible species and water-worn shell frag-ments show evidence of burning but not of charring.
Finally, no clear correlation appears when examining the spatial distribution by layer ofburnt/unburnt Nk shell beads and the location of hearths in the same layers (Fig. 10). A consistentnumber of unburnt shells are present in areas in which large hearths were found, particularly inlayer CC, and burnt shells occur in sub-squares in which no hearths were recorded. Groups ofshells found together in a sub-square associated with a hearth include burnt and unburnt shells.Also, the shell distribution does not fit the hypothesis that shell burning is due to heatingproduced by overlying hearths.
DISCUSSION AND CONCLUSIONS
Microscopic, Raman and EDAX analyses of experimentally heated Nk shells, dark Nk shells frommodern thanatocoenoses and MSA Nk shell beads identified firm criteria to distinguish heatedfrom unheated Nk beads, and showed that the dark colouring of the latter is due to heating. Inorder to formally demonstrate that the heating of the Nk was the consequence of a deliberateprocess seeking to produce dark ornaments, one should either find no traces of burning on othershell remains found in the same squares/levels or record on the latter traces of burning inproportions significantly different from those observed on the shell beads. The Blombos data donot conform to the first expectation, and match the second with such a degree of ambiguity thatit is difficult, at present, to reach a firm conclusion. The absence of calcined Nk and the substantialpresence of calcined shells from other species are consistent with the intention of darkening the
Accidental versus deliberate colour modification of shell beads 17
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
300 µm300 µm
180 µm
40 µm 30 µm30 µm
(a)
(b)
(c)
(d)
(e)
(f)
70 µm70 µm
300 µm
180 µm
40 µm
Figure 7 Optical (a) and SEM (b–f) photographs of the cross-section of an unheated modern Nassarius kraussianus(Nk) shell (a–c), and of a Nk shell heated in a reducing atmosphere at 300°C (d), 400°C (c) and 600°C (f).
18 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Nk in a controlled reductive environment, but cannot be considered, at this stage, as a convincingproof that Nk shells were intentionally heated. The spatial distribution of burnt and unburnt shellbeads supports, to some extent, intentional heating of the beads. If MSA Blombos Cave inhab-itants wore only unburnt shell beads and hearths were responsible for the blackening of lost shellbeads, one would expect to find all burnt shells in the hearths, which is not the case. On thecontrary, if MSA Blombos Cave inhabitants wore intentionally heated and unburnt shell beads,one would expect to find black and light shells in and outside hearths. This is due to the fact thathearths may have not been functional at the moment in which light beads were lost. This is thepattern that we observe at Blombos Cave. In order to verify this hypothesis, future research will
(a) (c)
(d)(b)
240 µm
30 µm30 µm
40 µm
40 µm40 µm
Figure 8 SEM photos of the cross-section of a Nassarius kraussianus (Nk) shell heated at 800°C in a reducingatmosphere (a, b) and of a Nk heated in the soil underneath an open fireplace (c, d).
Accidental versus deliberate colour modification of shell beads 19
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
need to focus on high-resolution analysis of the site formation processes to evaluate the degreeto which the spatial distribution of small items such as Nk shells may have been affected by syn-and post-depositional displacement.
ACKNOWLEDGEMENTS
We thank Gérard Blanc, Pierre Guibert, Kathrin Lange, Marlize Lombard, Renata GarciaMoreno, Catherine Perlès, Alain Queffelec, Ina Reiche and Jörg Schäfer for helpful discussions,Elisabeth Sellier for assistance with the SEM analysis, and Cécile Bossy and Alain Queffelec forgiving us access to the muffle furnace and the polishing machine. This research was funded bythe European Research Council (ERC) under the European Union’s Seventh Framework Pro-gramme (FP7/2007–2013)/ERC grant agreement no. 249587, the PROTEA French – SouthAfrican research programme, the Groupe de Recherche Internationale STAR of the CNRS, theWenner-Gren Foundation and the Projet Région Aquitaine Origines III. CSH was funded by aNational Research Foundation/Department of Science and Technology supported Chair at theUniversity of Witwatersrand, South Africa, and by a joint Norwegian Research Council/SouthAfrican National Research Foundation grant.
(a) (b)
(c) (d)
0.5 mm 0.5 mm
0.5 mm 0.1 mm
Figure 9 Heat cracks on experimentally heated Nassarius kraussianus (Nk) shells (a, b) and on Nk from the MiddleStone Age levels of Blombos Cave (c, d).
20 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Tabl
e4
The
freq
uenc
yof
unbu
rnt
(‘U
nbur
.’),
burn
t(‘
Bur
.’)
and
calc
inat
ed(‘
Cal
c.’)
shel
lsan
dsh
ell
frag
men
tsof
mar
ine
shel
lsp
ecie
sfr
omla
yer
CC
.Lar
gefr
agm
ents
are
>2cm
,med
ium
frag
men
tsbe
twee
n1
and
2cm
,and
smal
lfr
agm
ents
are
<1cm
.Res
idue
sco
rres
pond
mai
nly
tom
icro
flake
sof
nacr
e,pr
obab
lyof
Pern
ape
rna
orT
urbo
sarm
atic
us.I
ncid
enta
lsh
ells
corr
espo
ndto
smal
lga
stro
pods
,and
wat
er-w
orn
shel
lsto
roun
ded
frag
men
tsof
unde
term
ined
shel
lsp
ecie
s
Sub-
squa
re
H5a
H5c
H6b
I5c
n(%
)n
(%)
n(%
)n
(%)
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Per
nape
rna
MN
I3
–3
84
264
––
15
9C
ompl
ete
oral
mos
t–
––
2–
––
––
––
–L
arge
frag
men
ts*
1–
–5
––
40–
–3
11
Med
ium
frag
men
ts†
1–
236
3–
104
4–
–8
17Sm
all
frag
men
ts‡
1815
284
432
268
114
–30
89(6
5)(3
3)(2
)(2
5)(7
5)
Turb
osa
rmat
icus
MN
I4
13
71
–13
2–
203
3C
ompl
ete
oral
mos
t–
––
––
––
––
––
–L
arge
frag
men
ts*
4–
313
1–
262
–24
511
Med
ium
frag
men
ts†
–3
–12
5–
122
–2
73
Smal
lfr
agm
ents
‡7
4–
121
46–
154
171
3134
65(7
2)(2
8)(9
0)(1
0)(<
1)(2
4)(2
6)(5
0)
Scut
alas
taar
genv
ille
iM
NI
1–
–1
––
1–
–2
––
Com
plet
eor
alm
ost
––
––
––
––
–2
––
Lar
gefr
agm
ents
*–
––
––
–1
––
––
–M
ediu
mfr
agm
ents
†–
––
––
––
––
––
–Sm
all
frag
men
ts‡
1–
–2
––
––
––
––
Cym
bula
ocul
usM
NI
1–
–0.
50.
5–
2–
–6
1–
Com
plet
eor
alm
ost
––
––
––
1–
–4
1–
Lar
gefr
agm
ents
*–
––
––
–3
––
41
1M
ediu
mfr
agm
ents
†7
––
2–
––
4–
68
–Sm
all
frag
men
ts‡
9–
–5
5–
82
–8
94
Accidental versus deliberate colour modification of shell beads 21
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Tabl
e4
Con
tinu
ed
Sub-
squa
re
H5a
H5c
H6b
I5c
n(%
)n
(%)
n(%
)n
(%)
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Unb
ur.
Bur
.C
alc.
Din
opla
xgi
gas
MN
I0.
50.
5–
–1
–1
––
0.5
–0.
5C
ompl
ete
oral
mos
t–
––
––
––
––
Lar
gefr
agm
ents
*–
––
––
–3
––
1–
–M
ediu
mfr
agm
ents
†–
1–
–2
–7
––
––
1Sm
all
frag
men
ts‡
1–
––
9–
41
––
–1
Hal
ioti
ssp
.M
NI
1–
–1
––
––
–1
––
Com
plet
eor
alm
ost
––
––
––
––
––
––
Lar
gefr
agm
ents
*–
––
––
––
––
2–
–M
ediu
mfr
agm
ents
†1
––
––
––
––
––
–Sm
all
frag
men
ts‡
––
–2
––
––
––
––
Don
axsa
rra
MN
I–
––
––
–1
1–
––
–C
ompl
ete
oral
mos
t–
––
––
––
––
––
–L
arge
frag
men
ts*
––
––
––
––
––
––
Med
ium
frag
men
ts†
––
––
––
31
––
––
Smal
lfr
agm
ents
‡–
––
––
–2
––
––
–
Dil
oma
sp.
––
–1
––
1–
–1
––
Res
idue
s§13
050
–25
420
7–
n/a
n/a
n/a
n/a
n/a
n/a
(72)
(27)
(55)
(45)
Bar
nacl
es2
2–
91
–9
––
3–
–In
cide
ntal
s¶4
1–
32
–35
––
2–
–W
ater
-wor
n∥10
1–
414
–42
––
1–
–N
assa
rius
krau
ssia
nus
–4
–12
7–
12
–1
1–
*>2
cm;
†be
twee
n1
and
2cm
;‡
<1cm
;§
mic
rofla
kes
ofna
cre,
prob
ably
Per
nape
rna
and/
orTu
rbo
sarm
atic
us;
¶sm
all
gast
ropo
ds;
∥rou
nded
frag
men
tsof
unde
term
ined
shel
lsp
ecie
s.
22 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Figure 10 The spatial distribution of Nassarius kraussianus shell beads recovered at Blombos Cave according tocontextual and descriptive data. The dark grey and grey sub-squares indicate the location of hearths and ash areas (dataon hearths from Haaland 2012).
Accidental versus deliberate colour modification of shell beads 23
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
REFERENCES
Ambrose, S., 1998, Chronology of the later Stone Age and food production in East Africa, Journal of ArchaeologicalScience, 25, 377–92.
Bar-Yosef Mayer, D. E, Vandermeersch, B., and Bar-Yosef, O., 2009, Shells and ochre in Middle Paleolithic Qafzeh Cave,Israel: indications for modern behavior, Journal of Human Evolution, 56, 307–14.
Botha, R., 2008, Prehistoric shell beads as a window on language evolution, Language & Communication, 28(3),197–212.
Bouzouggar, A., Barton, N., Vanhaeren, M., d’Errico, F., Collcutt, S., Higham, T., Hodge, E., Parfitt, S., Rhodes, E.,Schwenninger, J.-L., Stringer, C., Turner, E., Ward, S., Moutmir, A., and Stambouli, A., 2007, 82,000-year-old shellbeads from North Africa and implications for the origins of modern human behavior, Proceedings of the NationalAcademy of Sciences, USA, 104, 9964–9.
Brown, K. S., Marean, C. W., Herries, A. I. R., Jacobs, Z., Tribolo, C., Braun, D., Roberts, D. L., Meyer, M. C., andBernatchez, J., 2009, Fire as an engineering tool of early modern humans, Science, 325, 859–62.
Claassen, C., 1998, Shells, Cambridge University Press, Cambridge.Coolidge, F. L., and Overmann, K. A., 2012, Numerosity, abstraction, and the emergence of symbolic thinking, Current
Anthropology, 53(2), 204–25.d’Errico, F., and Henshilwood, C. S., 2007, Additional evidence for bone technology in the southern African Middle
Stone Age, Journal of Human Evolution, 52, 142–63.d’Errico, F., and Vanhaeren, M., 2009, Earliest personal ornaments and their significance for the origin of language
debate, in The cradle of human language (eds. R. Botha and C. Knight), 16–40, Oxford University Press, Oxford.d’Errico, F., Henshilwood, Ch., and Nilssen, P., 2001, An engraved bone fragment from ca. 75 kyr Middle Stone Age
levels at Blombos Cave, South Africa: implications for the origin of symbolism and language, Antiquity, 75, 309–18.d’Errico, F., Vanhaeren, M., and Wadley, L., 2008, Possible shell beads from the Middle Stone Age layers of Sibudu Cave,
South Africa, Journal of Archaeological Science, 35, 2675–85.d’Errico, F., Henshilwood, C. S., Vanhaeren, M., and van Niekerk, K., 2005, Nassarius kraussianus shell beads from
Blombos Cave: evidence for symbolic behaviour in the Middle Stone Age, Journal of Human Evolution, 48, 3–24.d’Errico, F., Salomon, H., Vignaud, C., and Stringer, C., 2010, Pigments from the Middle Palaeolithic levels of es-Skhul
(Mount Carmel, Israel), Journal of Archaeological Science, 37(12), 3099–110.d’Errico, F., Backwell, L., Villa, P., Degano, I., Lucejko, J., Bamford, M., Higham, T., Colombini, M.-P., and Beaumont,
P., 2012, Early evidence of San material culture represented by organic artifacts from Border Cave, South Africa,Proceedings of the National Academy of Science, USA, 9(33), 13 214–19.
d’Errico, F., Vanhaeren, M., Barton, N., Bouzouggar, A., Mienis, H., Richter, D., Hublin, J-J., Mcpherron, S. P., andLozouet, P., 2009, Additional evidence on the use of personal ornaments in the Middle Paleolithic of North Africa,Proceedings of the National Academy of Science, USA, 106, 16 051–6.
Dissanayake, E., 2009, The Artification Hypothesis and its relevance to cognitive science, evolutionary aesthetics, andneuroaesthetics, Cognitive Semiotics, 5, 148–73.
Eiwanger, J., Mikdad, A., and Moser, J., 2009, Découverte de coquilles perforées de type Nassarius au site Ifri n’Ammar(Rif Oriental, Maroc), Bulletin d’Archéologie Marocaine, 22, 9–15.
Gliganic, L. A., Jacobs, Z., Roberts, R. G., Domínguez-Rodrigo M., and Mabulla, A. Z., 2012, New ages for Middle andLater Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz andfeldspar grains, Journal of Human Evolution, 62, 533–47.
Godfrey-Smith, D. I., and Ilani, S., 2004, Past thermal history of goethite and haematite fragments from Qafzeh cavededuced from thermal activation characteristics of 110°C TL peak of enclosed quartz grains, Revue d’Archéométrie,28, 185–90.
Haaland, M., 2012, Intra-site spatial analysis of the Still Bay Units in Blombos Cave, South Africa, Master’s dissertation,Department of Archaeology, History, Culture and Religion, University of Bergen, Bergen.
Hartzell, L. L., 1991, Archaeological evidence for stages of manufacture of Olivella shell beads in California, Journal ofCalifornia and Great Basin Anthropology, 13(1), 29–39.
Henshilwood, C. S., 2008a, Winds of change: palaeoenvironments, material culture and human behaviour in the LatePleistocene (c. 77–48 ka) in the Western Cape Province, South Africa, in Current themes in Middle Stone Ageresearch (eds. M. Lombard, C. Sievers and W. Ward), 35–51, Goodwin Series 10, South African ArchaeologicalSociety, Vlaeberg.
Henshilwood, C. S., 2008b, Holocene prehistory of the Southern Cape, South Africa: excavations at Blombos Caveand the Blombosfontein Nature Reserve, British Archaeological Reports International Series 1860, Archaeopress,Oxford.
24 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Henshilwood, C. S., and Dubreuil, B., 2009, Reading the artifacts: gleaning language skills from the Middle Stone Agein southern Africa, in The cradle of human language (eds. R. Botha and C. Knight), 41–60, Oxford University Press,Oxford.
Henshilwood, C. S., and Dubreuil, B., 2011, The Still Bay and Howiesons Poort, 77–59 ka: perspective-taking and theevolution of the modern human mind during the African Middle Stone Age, Current Anthropology, 52(3), 361–400.
Henshilwood, C. S., d’Errico, F., and Watts, I., 2009, Engraved ochres from the Middle Stone Age levels at BlombosCave, South Africa, Journal of Human Evolution, 57, 27–47.
Henshilwood, C. S., d’Errico, F., Marean, C. W., Milo, R. G., and Yates, R., 2001a, An early bone tool industry from theMiddle Stone Age at Blombos Cave, South Africa: implications for the origins of modern human behaviour,symbolism and language, Journal of Human Evolution, 41, 631–78.
Henshilwood, C. S., d’Errico, F., Vanhaeren, M., van Niekerk, K., and Jacobs, Z., 2004, Middle Stone Age shell beadsfrom South Africa, Science, 304, 403.
Henshilwood, C. S., d’Errico, F., Van Niekerk, K. L., Coquinot, Y., Jacobs, Z., Lauritzen, S.-E., Menu, M., andGarcía-Moreno, R., 2011, A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa, Science,334, 219–22.
Henshilwood, C. S., Sealy, J. C., Yates, R. J., Cruz-Uribe, K., Goldberg, P., Grine, F. E., Klein, R. G., Poggenpoel, C.,van Niekerk, K. L., and Watts, I., 2001b, Blombos Cave, Southern Cape, South Africa: preliminary report on the1992–1999 excavations of the Middle Stone Age levels, Journal of Archaeological Science, 28(5), 421–48.
Henshilwood, C. S., d’Errico, F., Yates, R., Jacobs, Z., Tribolo, C., Duller, G. A. T., Mercier, N., Sealy, J. C., Valladas,H., Watts, I., and Wintle, A. G., 2002, Emergence of modern human behavior: Middle Stone Age engravings fromSouth Africa, Science, 295, 1278–80.
Jacobs, Z., 2004, Development of luminescence techniques for dating Middle Stone Age sites in South Africa, Ph.D.dissertation, University of Wales, Aberystwyth.
Jacobs, Z., Duller, G. A. T., and Wintle, A. G., 2003a, Optical dating of dune sand from Blombos Cave, South Africa:II—single grain data, Journal of Human Evolution, 44(5), 613–25.
Jacobs, Z., Wintle, A. G., and Duller, G. A. T, 2003b, Optical dating of dune sand from Blombos Cave, South Africa:I—multiple grain data, Journal of Human Evolution, 44(5), 599–612.
Jacobs, Z., Duller, G. A. T., Wintle, A. G., and Henshilwood, C. S., 2006, Extending the chronology of deposits atBlombos Cave, South Africa, back to 140 ka using optical dating of single and multiple grains of quartz, Journal ofHuman Evolution, 51, 255–73.
Jacobs, Z., Hayes, E. H., Roberts, R. G., Galbraith, R. F., and Henshilwood, C. S., 2013, An improved OSL chronologyfor the Still Bay layers at Blombos Cave, South Africa: further tests of single-grain dating procedures and are-evaluation of the timing of the Still Bay industry across southern Africa, Journal of Archaeological Science, 40(1),579–94.
Jones, H. L., 2001, Electron spin resonance dating of tooth enamel at three Palaeolithic sites, Ph.D. dissertation,McMaster University, Canada.
Kandel, A. W., and Conard, N. J., 2005, Production sequences of ostrich eggshell beads and settlement dynamics in theGeelbek Dunes of the Western Cape, South Africa, Journal of Archaeological Science, 32, 1711–21.
Klein, R. G., 2008, Out of Africa and the evolution of human behaviour, Evolutionary Anthropology, 17, 267–81.Klein, R. G., and Steele, T. E., 2013, Archaeological shellfish size and later human evolution in Africa, Proceedings of
the National Academy of Sciences, USA, 110(27), 10 910–15.Kuhn, S., and Stiner, M., 2007, Body ornamentation as information technology: towards an understanding of the
significance of early beads, in Rethinking the human revolution (eds. P. Mellars, K. Boyle, O. Bar-Yosef and C.Stringer), 45–54, McDonald Institute Monographs, Cambridge.
Lange, K., Perlès, C., Vanhaeren, M., and Reiche, I., 2008, Heat induced modification of marine shells as personalornaments at the prehistoric site of Franchthi Cave, Greece: first results of a multianalytical approach, in 9thInternational Conference on NDT of Art, Jerusalem, Israel, 25–30 May 2008, http://www.ndt.net/search/docs.php3?MainSource=65.
McBrearty, S., and Brooks, A. S., 2000, The revolution that wasn’t: a new interpretation of the origin of modern humanbehaviour, Journal of Human Evolution, 39, 453–563.
McGuire, M. M., Jallad, K. N., Ben-Amotz, D., and Hamers, R. J., 2001, Chemical mapping of elemental sulfur onpyrite and arsenopyrite surfaces using near-infrared Raman imaging microscopy, Applied Surface Science, 178,105–15.
Mazza, P. P. A., Martini, F., Sala, B., Magi, M., Colombini, M. P., Giachi, G., Landucci, F., Lemorini, C., Modugno, F.,and Ribechini, E., 2006, A new Palaeolithic discovery: tar-hafted stone tools in a European mid-Pleistocene bone-bearing bed, Journal of Archaeological Science, 33, 1310–18.
Accidental versus deliberate colour modification of shell beads 25
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••
Mourre, V., Villa, P., and Henshilwood, C., 2010, Early use of pressure flaking on lithic artifacts at Blombos Cave, SouthAfrica, Science, 330, 659–62.
Nami, M., and Moser, J. (eds.), 2010, La Grotte d’Ifri n’Ammar. Tome 2. Le Paléolithique moyen, Forschungen zurArchäologie Außereuropäischer Kulturen 9, Dr Ludwig Reichert Verlag, Wiesbaden.
Pawlik, A. F., and Thissen, J. P., 2011, Hafted armatures and multi-component tool design at the Micoquian site ofInden-Altdorf, Germany, Journal of Archaeological Science, 38, 1699–708.
Perlès, C., and Vanhaeren, M., 2010, Black Cyclope neritea marine shell ornaments in the Upper Palaeolithic andMesolithic of Franchthi Cave, Greece: arguments for intentional heat treatment, Journal of Field Archaeology, 35(3),298–309.
Ray, S. C., Fanchini, G., Tagliaferro, A., Bose, B., and Dasgupta, D., 2003, Amorphous carbon films prepared by the ‘dip’technique: deposition and film characterization, Journal of Applied Physics, 94(2), 870–8.
Salomon, H., Vignaud, C., Coquinot, Y., Beck, L., Stringer, C., Strivay, D., and d’Errico, F., 2012, Selection and heatingof colouring materials in the Mousterian leves of Es-Skhul (c.100 000 years BP, Mount Carmel, Israel),Archaeometry, 54, 698–722.
Schmidt, P., Porraz, G., Slodczyk, A., Bellot-Gurlet, L., Archer, W., and Miller, C. E., 2013, Heat treatment in the SouthAfrican Middle Stone Age: temperature induced transformations of silcrete and their technological implications,Journal of Archaeological Science, 40(9), 3519–31.
Schoeman, S., 1983, Eloquent beads, the semantics of a Zulu art form, Africa Insight, 13(2), 5–25.Silverman, M. P., 1967, Mechanism of bacterial pyrite oxidation, Journal of Bacteriology, 94(4), 1046–51.Stiner, M., 1999, Palaeolithic mollusk exploitation at Riparo Mochi (Balzi Rossi, Italy): food and ornaments from the
Aurignacian through Epigravettian, Antiquity, 73(282), 735–54.Thompson, J., and Henshilwood, C. S., 2011, Taphonomic analysis of the Middle Stone Age large mammal faunal
assemblage from Blombos Cave, Southern Cape, South Africa, Journal of Human Evolution, 60, 746–67.Tribolo, C., 2003, Apports des méthodes de la luminescence à la chronologie de techno-faciès du Middle Stone Age
associés aux premiers hommes modernes d’Afrique du Sud, Ph.D. dissertation, Université Bordeaux 1, Talence.Tribolo, C., Mercier, N., Selo, M., Valladas, H., Joron, J.-L., Reyss, J.-L., Henshilwood, C., Sealy, J., and Yates, R., 2006,
TL dating of burnt lithics from Blombos Cave (South Africa) and the antiquity of modern behavior, Archaeometry,48, 341–57.
Urmos, J., Sharma, S. K., and Mackenzie, F. T., 1991, Characterization of some biogenic carbonates with Ramanspectroscopy, American Mineralogist, 76, 641–6.
Vanhaeren, M., and d’Errico, F., 2006, Clinal distribution of personal ornaments reveals the ethno-linguistic geographyof Early Upper Palaeolithic Europe, Journal of Archaeological Science, 33(8), 1105–28.
Vanhaeren, M., d’Errico, F., van Niekerk, K. L., Henshilwood, C. S., and Erasmus, R. M., 2013, Thinking strings:additional evidence for personal ornament use in the Middle Stone Age at Blombos Cave, South Africa, Journal ofHuman Evolution, 64(6), 500–17.
Vanhaeren, M., d’Errico, F., Stringer, C., James, S. L., Todd, J., and Mienis, H. K., 2006, Middle Palaeolithic shell beadsin Israel and Algeria, Science, 312, 1785–8.
Villa, P., Soressi, M., Henshilwood, C. S., and Mourre, V., 2009, The Still Bay points of Blombos Cave (South Africa),Journal of Archaeological Science, 36, 441–60.
Wadley, L., Hodgskiss, T., and Grant, M., 2009, Implications for complex cognition from the hafting of tools withcompound adhesives in the Middle Stone Age, South Africa, Proceedings of the National Academy of Sciences, USA,106, 9590–4.
Wickler, W., and Seibt, I., 1995, Syntax and semantics in a Zulu bead colour communication system, Anthropos, 90,391–405.
Withnall, R., Chowdhry, B. Z., Silver, J., Edwards, H. G. M., and de Oliveira, L. F. C., 2003, Raman spectra of carotenoidsin natural products, Spectrochim Acta A, 59(10), 2207–12.
Wynn, T., and Coolidge, F., 2007, Did a small but significant enhancement in working memory capacity power theevolution of modern thinking? In Rethinking the human revolution (eds. P. Mellars, K. Boyle, O. Bar-Yosef and C.Stringer), 79–90, McDonald Institute Monographs, Cambridge.
26 F. d’Errico et al.
© 2013 University of Oxford, Archaeometry ••, •• (2013) ••–••