The stylistically Paleolithic petroglyphs
of the Côa valley (Portugal) are of Paleolithic age
A refutation of their <<direct dating>> to recent
times
João Zilhão
8. Bednarik's arguments on context
Most of the contextual arguments referred to by Bednarik in his dating report
to EDP (Bednarik 1995b) are essentially the same which he developed in Australia
before ever having set foot in Portugal, as stated in a paper published
in the April 1995 issue of the AURA Newsletter (Bednarik 1995a). He had
been informed in a reply sent to him by the present author, which he received
before his trip to the Côa, that these arguments were ill-founded.
Notwithstanding, he used them in his report to EDP and has developed them
even further in a paper to appear in a coming issue of Rock Art Research
(Bednarik n. d.).
Detailed information on Portuguese Upper Paleolithic faunas can be found
in Cardoso (1993). The chronological, environmental and cultural evidence
for the same period has been systematically reviewed in Zilhão (1995a).
Marks et al. (1994), Póvoas et al. (1992) and Zilhão (1988,
1989, 1990, 1991, 1993, 1994) contain partial discussions of the relevant
data in English or French.
8.1. Frost-weathering
In the littoral region of Estremadura, due to its proximity to the at times
very cold waters of the Atlantic, last glacial cryoclastism of limestones
is known almost down to present sea level (Daveau 1980). But, as demonstrated
by recent work on slope (Rodrigues 1991) and cave (Zilhão 1995) deposits,
below 400 m this process does not seem to occur after the last glacial maximum,
coming to an end with the Upper Solutrean, at the time (ca. 17,000 BP) when
a very warm oscillation is recorded in sea surface temperatures off the
Portuguese coast, which by then reached almost modern levels (Bard et al.
1992; Duplessy et al. 1992). Despite subsequent cold oscillations at sea,
from then on the limestone hills and plateaus of this littoral region seem,
on present evidence, to become covered by oak forests, and ibex and chamois
disappear from the faunal assemblages. If, for the sake of argument, one
used this littoral region as a model for the interior, and conceded that
frost-weathering might have been a problem for the preservation of engravings
of Solutrean age, the argument would still be simply untenable for the Magdalenian
period. In the interior regions of North and Central Portugal, however,
as a result of extreme dryness and different lithology (schists and granites
instead of limestones), periglacial features such as cryoclastic slope deposits
are unknown below an elevation of 700 m above modern sea level, so there
is absolutely no basis to believe frost-weathering would have affected the
low lying (ca. 100 m) and sheltered valley of the Côa, especially
after deglaciation in the Cantabrian mountains and in the Serra da Estrela
was completed, some time between 16,000 and 14,000 years ago (Turner and
Hannon 1988). In any case, test excavations carried out at the newly found
archaeological site of Cardina, located in the Côa valley itself (see
below), have now settled the issue: here, the deposits containing a Late
Gravettian (ca. 22,000 BP) archaeological context are coluvial sands entirely
devoid of cryoclasts.
8.2. River erosion
Bednarik (1995a) argues that the fact petroglyphs occur right down to the
floor of the Côa valley, only a few meters above water, makes it difficult
to understand how Upper Paleolithic art could have survived the many fluctuations
in river level that, based on evidence from other European rivers, must
have happened in the Côa since the end of the Pleistocene. This is
simply not a problem. Preservation of last glacial maximum archaeological
remains in the flood plain of modern Portuguese rivers is demonstrated,
for instance, at Terra do Manuel, where a radiocarbon dated 22,000 year
old living floor located ca. 1 m below the surface was excavated in 1988-89
(Zilhão 1995a). In this part of the country, this is explained by
the pattern of downcutting caused by eustatic response to lowered sea levels.
Fluviatile terraces accumulated at the beginning of isotope stage 2 were
thus exposed as beaches that were made available to human occupation, and
were indeed occupied. Coluvial and eolian accumulation of sediments eroded
from the extant slopes largely denuded of vegetation subsequently buried
and protected these sites from Tardiglacial and Holocene erosion. The lowest
panels at Penascosa and Ribeira de Piscos are, as far as elevation above
the river is concerned, in a topographical position even more favorable,
from the point of view of preservation, than that of the Late Gravettian
and Proto- Solutrean habitation site of Terra do Manuel. There is therefore
no reason to suggest, until detailed geological studies of the valley (as
yet unavailable) eventually show otherwise, that such a position is incompatible
with a Paleolithic age for the engravings. In other words, elevation above
the river is, per se, a totally irrelevant issue for the argument concerning
the chronology of the Côa petroglyphs.
8.3. Absence of cold adapted species
It is true that, as Bednarik (1995a) notes, cave bear, bison, mammoth, woolly
rhino and reindeer are not present in the Côa art. But this is exactly
what should be expected: they are not present either at any of the many
Upper Paleolithic paleontological and archaeological sites that are known
in Portugal and in Mediterranean Spain (Fig. 5),
although Cardoso (1993) does cite one occurrence of mammoth in his list
of Quaternary faunal remains from Portugal. The bone in question is a large
shaft fragment classified as part of the femur of an elephantid, which he
reasons should be a mammoth because other bones from the same site (Algar
de João Ramos) were radiocarbon dated to ca. 14,000 BP, making an
attribution to Elephas antiquus impossible. This reasoning, however, assumes
that the faunal assemblage from this purely paleontological site is homogeneous
and dates to a single period, which does not seem reasonable in a stratified
cave environment poorly excavated in the late nineteenth century. In this
context, it seems more reasonable to admit that the bone fragment in question
does belong to Elephas antiquus, a species which, as Cardoso (1993) shows,
survived in Portugal up to ca. 30,000 BP and could well have been represented
in the otherwise quite banal Upper Pleistocene faunal assemblage from Algar
de João Ramos.
All available evidence therefore suggests that the Atlantic and Mediterranean
façades of Iberia, south of the Ebro, may have constituted a separate
faunal province, where cold adapted species, even at the level of micromammals
(Póvoas et al. 1994), did not penetrate (Aura and Villaverde 1995).
Those species are also completely absent from the thousands of engraved
slabs found in the Gravettian, Solutrean and Magdalenian levels of the deeply
stratified cave site of Parpalló (Valencia), which were found in
very rich, and radiocarbon dated, archaeological deposits, spanning the
Gravettian, Solutrean and Magdalenian periods (Villaverde 1994). Horse,
aurochs, red deer and ibex, plus the occasional chamois, bird or carnivore,
that is, exactly the same species as those whose bones have been recovered
in the archaeological deposits (Davidson 1983), are the animals represented
in these works of mobiliary art (Table 1). Stylistically, such representations
are also strikingly close to those found in the Côa and, given their
archaeological context, are known to be of Paleolithic age beyond any reasonable
doubt.
TABLE 1
Parpalló Upper Paleolithic decorated stone slabs
Animal species represented (a)
| G | LS | EMS | LMS |
US | SGI | SGII | SGIII | EMA | EMB
| UM | GAL | Other | Total |
| Aurochs | 2 | 6 | 6 | 1 | 3 | 2
| 1 | 1 | 2 | 10 | 7 | 15 | 3
| 59 |
| Horse | 1 | 7 | 14 | 8 | 12 | 20
| 6 | 9 | 9 | 12 | 15 | 10 | 5
| 128 |
| Deer | - | 14 | 19 | 7 | 6 | 6
| 3 | - | 8 | 16 | 8 | 14 | 4
| 105 |
| Ibex | 2 | 8 | 19 | 5 | 10 | 8
| 16 | 6 | 8 | 16 | 9 | 22 | 11
| 136 |
| Other (b) | - | 1 | 4 | - | -
| - | - | - | 1 | 2 | 6 | 2
| 2 | 18 |
| Undetermined | 2 | 27 | 42 | 29 | 19
| 19 | 9 | 14 | 19 | 29 | 25 | 51
| 32 | 320 |
| Total | 7 | 63 | 104 | 50 | 55
| 55 | 35 | 30 | 47 | 85 | 70
| 114 | 57 | 766 |
(a) after Villaverde (1994:Table 26, modified); G - Gravettian; LS - Lower
Solutrean; EMS - Early Middle Solutrean; LMS - Late Middle Solutrean; US
- Upper Solutrean; SGI - Solutreo- gravettian I; SGII - Solutreo- gravettian
II; SGIII - Solutreo- gravettian III; EMA - Early Magdalenian A; EMB - Early
Magdalenian B; UM - Upper Magdalenian; GAL - galleries (surface)
(b) chamois, fox, lynx, wild boar, wolf, mustelids and birds
Bednarik (n.d.) objects to these observations at two levels, one is factual,
the other theoretical. At the factual level he restates, based on outdated
(more than twenty year old) references, that cave bear is indeed present
in two Portuguese faunal assemblages from the Pleistocene (those recovered
at Furninha and Salemas), and that the geographical distribution of cave
bear remains, which <<resembles the distribution of limestone karsts
in Europe>>, indicates <<a massive taphonomic bias>>:
<<the apparent absence of cave bear remains in regions lacking limestone
caves (such as most parts of Portugal) tells us absolutely nothing about
the former range of the species>>. This argument insists on an error
of fact and entirely misses the point. The references to cave bear at Salemas
are based on mistaken preliminary identifications by Zbyszewski (1963),
subsequently accepted by Ferreira (1964) and Roche (1971, 1972); they have
been corrected since by Torres (1979) and Cardoso (1993), who referred those
remains to Ursus arctos. The bear remains recovered at Furninha have always
been attributed to Ursus arctos since they were first studied by Harlé
(1910-11). As a result, both Harlé (1910-11) and all subsequent authorities
have given a categorical verdict on Ursus spelaeus in Portugal: the only
bear species that can be recognized in the Quaternary faunal remains from
the country is Ursus arctos (Torres 1979; Cardoso 1993). Therefore, Bednarik's
taphonomic argument is irrelevant: the issue at stake is not why cave bear
remains have not been found in non-limestone areas of Portugal, but why
the species has never been found in Portuguese limestone cave deposits.
Since Cardoso (1993) reviews 21 cave sites spread all over the country,
the absence of such remains is not easily explained away as due to deficient
sampling. This brings up Bednarik's theoretical argument regarding cave
bear and cold-adapted species: that <<absence of evidence>>
does not equal <<evidence of absence>>, that is, that remains
of those species may eventually be recovered in other regions of the country
or in new, as yet unknown, sites. This is a quintessentially non-scientific
style of reasoning, one that is commonly found in Christian fundamentalist
literature under the form, for instance, of statements such as <<God
exists because no one can prove that he doesn't>>. It is also a common
argument in anti-evolutionist thinking, for instance under the form of statements
like this: <<the fact that trilobites are absent from post-Paleozoic
beds and dinosaurs are absent from pre-Mesozoic ones does not mean that
their remains will not eventually be found in such deposits>>. If
Bednarik were right in that criteria of absence cannot be accepted as scientific
evidence, not only archaeology but also geology and paleontology would fall
outside the scope of science.
The fact, however, is that, whether Bednarik likes it or not, these are
well established disciplines that have developed their own scientific methodology
and, in particular, have learned to deal with the issues regarding patterns
of presence and absence in terms of probability statements (Dawkins 1991).
For instance, given our present data base of Paleozoic and Mesozoic deposits,
the probability that trilobites and dinosaurs were actually contemporaneous
is so small that, for all practical purposes, such contemporaneity can be
assessed as an impossibility. The data base of Portuguese Quaternary faunas
is not as large as that of fossiliferous Paleozoic and Mesozoic beds all
over the world, so the probability that bison, cave bear, mammoth, reindeer
and woolly rhino may one day be found is not as small as in the dinosaur/trilobite
example, and it cannot be considered a total impossibility, particularly
in those parts of the country that are closer to the known past ranges of
those species. Such a data base is, however, large enough to suggest that,
if present at all, those cold-adapted species would probably have occurred
only as very small and marginal populations (or even as stranded individuals)
that one would not be correct in considering as part of the daily environment
of Upper Paleolithic hunter-gatherers living along the western and southern
shores of Iberia. The tentative (and questionable) identification of bison,
megaloceros, reindeer and woolly rhino among the fine lined engravings of
Siega Verde (Balbín et al. 1995), already in Spain but only some
60 km southeast of the Côa complex of art sites, might be taken, if
confirmed by future research, as an indication of such infrequent occurrences.
Meanwhile, <<absence of evidence>> should indeed be considered,
in this case, as <<evidence of absence>>.
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