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population density, Giles Pacheco et al. (2003) concluded that human popula-
tions during this long period were constant and low. There was no real change
during the ¬rst phases of the Upper Palaeolithic. In fact the data suggested a pop-
ulation decline in the Aurignacian and only a slight recovery in the Gravettian
166 Neanderthals and Modern Humans

10000


1000


100


10


1


0.1
-375 -125 -33.5 -23.75 -18.5 -13.5 -8.5 -6.1 -5.4



Figure 7.5. Decrease in duration (log duration) of cultural periods through time (bars).
Note the signi¬cant in¬‚exions at the start of the Upper Palaeolithic and the Neolithic.
Curve shows best model ¬t. The relationship is highly statistically signi¬cant (R2 =
1.000; P < 0.0001) and is best described by a cubic regression model (y = 4.4353 +
0.469x + 0.0248x2 + 5.8 — 10’5 x3 ). White bars, Middle Paleolithic (Acheulian,
Mousterian); grey bars, Upper Paleolithic (Aurignacian, Gravettian, Magdalenian,
Epipalaeolithic, early Neolithic, advanced Neolithic). After Giles Pacheco et al.
(2003).



(Figure 7.4). These results are in keeping with the view (see next section) that
there was a hiatus in southern Iberia between the extinction of the Neanderthals
and the arrival of the ¬rst modern humans. The dramatic increase during the
Solutrean was considered too great to be a mere artefact of sampling. Its coin-
cidence with the LGM was in keeping with the thesis that it was a phenomenon
that re¬‚ected a ˜refugium effect™ (Straus, 2000) at a time when humans were
virtually con¬ned to the southern European peninsulas (Gamble, 1999). The
results were indicative of populations that were tracking steppe environments,
a phenomenon that commenced with the Aurignacian in the central Eurasian
Plain (Otte, 1994; Semino et al., 2000; Finlayson, 2003). This conclusion was
supported by the apparent population decline during the Magdalenian (Figure
7.4) that suggested that these populations continued to be adapted to steppe
environments that were receding at the expense of forest with the post-LGM
warming (see also Chapter 8). It coincided with a density increase in north-
ern Spain and in sites at higher elevations (Straus & Winegardner, 2000) at
this time which was in keeping with an ˜inverse™ resource tracking and was
Modern Human colonisation and Neanderthal extinction 167


(a) Warm -30



-35


Mean
δ18O
-40




Cold -45
-125 -33.5 -23.75 -18.5 -13.5 -8.5 -6.1 -5.4

Time Mode (kyr)




-3
(b)

-3.5


-4


-4.5


-5


-5.5


-6
-125 -33.5 -23.75 -18.5 -13.5 -8.5 -6.1 -5.4




Figure 7.6. (a) Pattern of temperature by time periods related to major cultural periods
(bars). Curve shows best model ¬t. The relationship is highly statistically signi¬cant
(R2 = 0.836; P = 0.011) and is best described by a quadratic regression model (y =
’33.583 + 0.3271x + 0.0022x2 ). After Giles Pacheco et al. (2003). (b) Pattern of
climatic stability (log n coef¬cient of variation) by time periods related to major
cultural periods (bars). Curve shows best model ¬t. The relationship is highly
statistically signi¬cant (R2 = 0.806; P < 0.002) and is best described by an S
regression model (ln(y) = ’3.2242 + (’10.5197/x)). After Giles Pachecho et al.
(2003). For explanation of bars see Figure 7.5.
168 Neanderthals and Modern Humans


(a)

100
Log Sites/Millenium




10




1



0.1




0.01
’42 ’41 ’38
’40 ’39 ’37 ’35 ’34
’36
Temperature (Mean δ18O)



600
(b)



400
Sites/Millennium




200



0



’200
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Coefficient of Variation


Figure 7.7. (a) Relationship between density of sites (log sites/millennium) and
temperature. Curve shows best model ¬t. R2 = 0.604; P = 0.023. The relationship is
best described by an exponential regression model (y = 2.0 — 1013 (e2 (0.769x)). After
Giles Pacheco et al. (2003). (b) Relationship between density of sites and climate
stability. Curve shows best model ¬t. The relationship between site density and climate
stability is even stronger than in (a) (R 2 = 0.95; P < 0.005) and is best described by a
cubic regression model (y = 503.737 ’ 78268x + 3737111x2 ’ 6.0 — 10’7 x3 ).
Modern Human colonisation and Neanderthal extinction 169

consistent with genetic evidence of south-west to north-east post-glacial dis-
persions (Torroni et al., 1998, 2001). The population recovery that commenced
at the beginning of the Holocene preceded the Neolithic (Figure 7.4) and sug-
gests an adjustment of local hunter“gatherer groups to the stabilising climatic
conditions. The massive and unprecedented subsequent Neolithic population
increase re¬‚ected a combination of rapid colonisation by eastern populations
(Semino et al., 2000; Zilhao, 2001) and an increase in environmental carrying
capacity through the introduction of production economies aided by warm and
stable climatic conditions.
The duration of cultures decreased signi¬cantly and the rate of decrease ac-
celerated with the onset of the Upper Palaeolithic (Figure 7.5). This indicated a
signi¬cant quantitative change with the arrival of modern humans at a scale that
was only subsequently matched with the onset of Holocene conditions and the
introduction of the Neolithic (Figure 7.5). This signi¬cant shortening of cultural
periods re¬‚ected an increase in cultural turnover. The Upper Palaeolithic shift
may re¬‚ect, in some measure, increased mobility and enhanced social networks
(Gamble, 1986, 1999; Finlayson et al., 2000a), and therefore an increase in cul-
tural interchange, in people with morphologies very suited to such a landscape
exploitation strategy. The Neolithic change may re¬‚ect the increased turnover
related to population migrations (Zilhao, 2001).
The climatic trends during the period studied were of increasing tempera-
ture and climatic stability through time (Figures 7.6a,b). The trends accelerated
signi¬cantly after the LGM. Site density increased with temperature and cli-
matic stability (Figures 7.7a,b). A very signi¬cant result of this study was the
much stronger relationship with climatic stability than with temperature. This
result supports the view (Finlayson et al., 2000a; Finlayson, 2003; this book)
that climatic instability was a major factor in the distribution and abundance of
human populations during the Pleistocene. Finlayson & Giles Pacheco (2000)
have shown that the distribution pattern of sites of human occupation in the
late Pleistocene in southern Iberia shifted from use of open air sites to an in-
creasing use of cave sites, especially in the Upper Palaeolithic. The relationship
reported by Giles Pacheco et al. (2003) between site density and temperature
and climate stability indicates that there have been signi¬cant human responses
to climate change that have included demographic and dispersion responses.
As Finlayson & Giles Pacheco (2000) and Finlayson et al. (2000a) have indi-
cated this has meant that there may have been times of climatic instability that
effectively generated a depopulation of southern Iberia, an effect that has also
been reported for Italy and the Balkans (Raposo, 2000), Central Asia (Davis &
Ranov, 1999) and the Middle East (Bar-Yosef, 1996) at the same time. The
most conspicuous case is the population response to the climatic instability of
170 Neanderthals and Modern Humans

OIS 3 that led to the Neanderthal extinction (see next section). There are two
events in the period studied that depart notably from the modelled trend. The
¬rst is the Solutrean expansion that coincided with the LGM and the second
was the Neolithic population expansion. The latter is well-documented to re-
late to the arrival of populations from outside the region (Zilhao, 2001). The
Solutrean demographic expansion is also likely to be at least in part a re¬‚ection
of the arrival of humans, probably steppe-adapted from the north, as steppe
environments closed in western Europe and opened up in Iberia (Figure 6.2).
There is signi¬cant evidence of population decline and a bottleneck in west-
ern Europe (Demars, 1996; Bocquet-Appel & Demars, 2000a; Richards et al.,
2000) coinciding with the Solutrean expansion in Iberia. Straus & Winegardner
(2000) have estimated site densities for the Atlantic“Cantabrian and Mediter-
ranean regions of Iberia during the Upper Palaeolithic. Giles Pacheco et al.™s
(2003) data for the corresponding period closely correlated with Straus & Wine-
gardner™s (2000) Mediterranean data. Neither was signi¬cantly correlated with
the Atlantic“Cantabrian data indicating that this latter region has behaved dif-
ferently in respect to human occupation (Figure 7.8). Such a conclusion is in
keeping with Finlayson™s (1999) and Finlayson et al.™s (2000a) distinction of
this region as bioclimatically Euro-Siberian or temperate oceanic, with greater
af¬nities to western Europe that to the rest of Iberia (see next section). Thus,
the Aurignacian and Gravettian are much more signi¬cant in the Atlantic“
Cantabrian region than anywhere to the south. There is also a north“south trend
for the Gravettian, which represents a dual effect: (1) the earlier arrival of steppe
environments in bioclimatic zones that were closer to those of western Europe;
and (2) a distance effect as people took longer to reach southern Iberia. We can
contrast the Iberian pattern with that of the more continental Italian and Balkan
peninsulas that also happened to be further east and therefore closer to the source
of the Aurignacian. In Greece, an Upper Palaeolithic industry with blades with
curved back and microliths dated to 40 kyr precedes the Aurignacian (dated at
32 kyr) (Koumouzelis et al., 2001) and suggests local adaptation to changing
circumstances in the heterogeneous mid-latitude belt, that we would expect
to reach that part of the world sooner than the west, followed by the arrival
of the Aurignacians and their slow in¬ltration of these environments. In Italy,
the Aurignacian reaches south to Sicily (Chilardi et al., 1996). These patterns,
including the early arrival of the Aurignacian to northern Iberia, contrast with
the late or non-arrival of the Aurignacian to southern Iberia.
Another noteworthy difference between northern and southern Iberia is the
response to the deglaciation after the LGM. There was a population decline in the
Magdalenian followed by a subsequent expansion in the Epipalaeolithic (Fig-
ure 7.8). Giles Pacheco et al. (2003) interpreted this to mean that the Magdale-
nian people of southern Iberia were the same as the Solutreans with a primary
(a) 30




20



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