The database (recorded with Excel) that has been used includes a relatively large number of variables that respond to particular scientific questions (Fig. 3.27), especially concerning the taphonomic history of the remains. The basis for their recording is the premise that formation processes leave characteristic traces on
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the archaeological record and that they can be approached when they are systematically evaluated on a seed-by-seed basis. These variables were defined following other authors (Boardman & Jones 1990, Hubbard &
al Azm 1990, Valamoti 2002, Braadbaart et al. 2004, Bouby, Fages & Treffort 2005, Braadbaart 2008) and also a small number of experiments carried out by myself (see Annex II; Antolín 2012). A detailed presentation of the database is available from previous publications (Antolín 2010b, Antolín & Buxó 2011c, Antolín 2012,). Nonetheless, a complete list of variables is presented in Fig.3.27., together with some hints concerning the questions that are aimed to answer and the type of recording (whether it is a nominal or an ordinal variable).
CATEGORY AIM TYPE OF RECORDING
NUMBER
General information concerning the storage of each item (reference number + bag number) and the context from where it came (site, chronology, archaeological feature)
REPRESENTED PART part of the plant identified Text (Fig. 3.28)
NUMBER OF REMAINS number
PRESERVATION TYPE 1: charred to 5: subfossil ordinal ranking number
NUMBER OF PARTS number
FRAGMENTED PART for cereals, part of the grain that is preserved text (Fig. 3.29) DEGREE OF FRAGMENTATION
Several variables that are aimed to describe the postdepositional history of the remains (chapter 3.2.10.3) depositional history of the remains (charring conditions) (chapter 3.2.10.2)
yes/no (Fig. 3.38)
PROT (seed with protrusions) yes/no (Fig. 3.38)
AG (aggregated seeds) yes/no (Fig. 3.38)
PELL (glumes preserved) yes/no
CC (concave flanks) yes/no
CT (cracked testa - for legumes) yes/no (Fig. 3.38)
Ocot (open cotyledons - for legumes) yes/no (Fig. 3.38)
DEFP (deformation by pressure) yes/no crop processing methods or storage conditions (chapter 3.2.10.1)
Fig. 3.27. List of variables that are recorded in the database.
Maximum accuracy is always aimed in the description of the plant parts represented. The complete list is offered below (Fig. 3.28). However, the use of such a relatively precise vocabulary implied a lot of processing of the data before producing the final tables (which mainly reflect the conventional categories).
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agg. grains + FPreC laterally perforated bead
amorphous object leaf fragment
cut/peeled grain rachis fragment + 1 grain
ear fragment rachis internode fragment
fruit flesh and pericarp fragment straw fragment
fruit flesh fragment straw node
Fig. 3.28. List of categories used to describe the represented part of each taxon (FPostC: fragment produced prior to charring; FPreC: fragment produced prior to charring).
The nomenclature of the fragmented part of cereal grains was presented elsewhere (Antolín 2008b, Antolín
& Alonso 2009, Antolín 2010b, Antolín & Buxó 2011c) (Fig. 3.29).
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Fig. 3.29. Nomenclature for the fragmented part of cereal grains used for the calculation of the MNI (Antolín 2008b).
Finally, some further details concerning the scoring for the degree of fragmentation should be added. This has been specifically designed for some taxa (see Fig. 3.30).
Taxa Scoring
Cereals (charred grain) 1= < 1 mm 2= 1-1,9 mm 3= 2-2,9 mm 4= > 3 mm Acorn pericarp
(waterlogged)
1= ≤25 mm2 2= 26-50 mm2 3= >50 mm2
Acorn kernel (charred) 1=less than half a cotyledon and without distal or basal end 2= less than half a cotyledon but with distal or basal end 3= more than half a cotyledon
Hazelnut pericarp
(waterlogged or charred) 1= ≤ 15 mm2 2= 16-50 mm2 3= > 50 mm2
Rest of the taxa 1 = less than half of the grain/fruit
2 = half or more than half of the grain/fruit
Fig. 3.30. Scoring criteria for recording the degree of fragmentation for the different taxa.
3.2.6. Techniques of numerical description of seed and fruit remains: NR, CU, MNI and density Archaeobotanical data can be described in a variety of ways, from semi-quantitative systems (presence/absence or scales of abundance) to fully quantitative descriptions. Each of them has advantages and disadvantages (see, for instance, Jones 1991). Semi-quantitative systems are especially useful when sites or particular chronological phases are very well known (through quantitative analyses) and the only interest is to record major trends and the taxonomic diversity. They are also valuable for preliminary evaluations previous to more thorough analyses, or for the rapid screening of large samples (Vandorpe 2010).
Quantitative systems allow comparisons between sites/features in terms of concentration of items per litre of sediment, as well as with experimental or ethnographic reference materials. They are, for this reason, necessary in order to reach significant taphonomic and palaeoeconomic evaluations.
Both systems were used in this work, but in most occasions fully quantitative approaches were carried out.
Some samples, mainly from La Draga site, were rapidly scanned, sorted and semi-quantified. These samples
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had been roughly water-screened at the site and they were mainly taken in order to recover large items that had few chances of being represented in the small systematic samples. This semi-quantification mainly consisted on a rough and fast counting of complete seeds just for getting a general idea of the composition of the samples.
Numerical descriptions are a way of presenting results in an objective way. But, how exact should they be?
Is it enough to count the number of remains (NR), should counting units (CU) be defined even if these do not represent a minimum number of individuals (MNI)? Why should one want to quantify 35 individuals instead of 18 CU, or 3000 remains instead of an MNI of 250? At some point, numbers become rather meaningless (Hubbard 1980) and small differences are not statistically significant. In our case, we expect to obtain results, which can be compared to those from other studies and to reference ethnographic or experimental work in order to reach a better understanding of taphonomic processes and the representativity of each assemblage. Besides, as will be commented more in detail in the following chapters, a lot of thresholds are used in archaeobotany: in order to choose suitable samples for palaeoeconomic analyses (>35,
>50 or >100 crop items), in order to determine whether they are “pure” or mixed (90% of one single taxon), in order to consider a sample accurate concerning the relative frecuency (proportion) of the best represented taxa (>384 items). As long as we depend on those thresholds, which are actually useful (but somewhat arbitrary in some occasions), there is a need for exact quantification. The need of exact quantification is more evident in small assemblages, where the largest MNI possible is aimed. The results obtained for large assemblages might not change significantly using one method or another: an average “loss” of 20% was observed in previous works with heavily fragmented assemblages when only embryo ends were counted (Antolín & Buxó 2011c), a lower proportion would be expected in better preserved ones.
In cases where comparisons are necessary, one should aim to quantify the materials in the same way as they were quantified in previous archaeobotanical analyses, experimental or ethnographic work. But only as long as that is possible and as long as other factors are not affecting the quantification of the archaeobotanical remains. For instance, embryo ends of cereal grains were counted in order to present ethnographic reference data concerning the ratios between cereal grain, chaff and weeds in each of the processing stages of a harvested crop (Jones 1990). A resulting database was obtained which has been used by many archaeobotanists as a reference for interpreting their archaeological assemblages. Usually the same quantification methods are used, aiming for some methodological coherence. But a charred assemblage of grain has a rather different state of preservation than that of a freshly threshed crop. Therefore, counting embryo ends might not lead to the most accurate MNI possible as in the ethnographic material. For this reason, another method, which takes into consideration all recognizable grain fragments, was proposed (Antolín 2008b). A similar method to that proposed by myself was actually practiced by other archaeobotanists (e.g. Van der Veen 1992, Valamoti 2004). But reaching an MNI is not possible in all cases.
The quantification of seed and fruit remains is complex, as already stated by other authors (Jones 1991), due to the frequent impossibility of counting a minimum number of plants (one can only aim to get a minimum number of seeds/fruits in many cases). And sometimes even reaching this goal is somewhat unfeasible. A good example for this would be subfossil pericarps of acorn. In these cases, a counting unit (CU) needs to be determined: for instance, a fragment above 25 mm2 (Hosch & Jacomet 2004). Establishing a CU is a useful counting strategy in order to not over-represent a taxon but it is not an MNI, for which the problem of over-representation may still not be solved. In many other cases, including all rare taxa, presenting the number of remains does not affect any statistical approach to the record and calculating an MNI becomes unnecessary. Finally, there are some types of remains for which counting CU or MNI is not possible because the material has been intentionally fragmented due to some processing. That would be the case of the
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fragments of grain produced prior to charring. These are produced during threshing, dehusking or bulgur preparation. Their quantification should be carried out by counting NR, since any other approach would be too complex given the difficulty of recognizing anatomical features. Besides, these are relatively rare finds and their quantification as NR does not imply a large effort.
A fast look at the quantification techniques used by different researchers leads to the discouraging conclusion that quantification methods are not homogeneous. This lack of homogeneity can be observed in many studies. For instance, slightly different counting systems were used by M. Van der Veen (1992) and S.M. Valamoti (2004) concerning cereal chaff remains; while the quantification of wild fruits like hazelnuts has been attempted by using weight (e.g. McComb & Simpson 1999, Mithen et al. 2001), volume (e.g.
Marinval 2008) and absolute counts of CU (Hosch & Jacomet 2004, Martin 2010) or the total NR (many studies, e.g. Zapata 2001, Antolín & Alonso 2009, Salavert 2011, Antolín et al. 2010, Antolín & Buxó 2011b) (for a more in depth discussion on hazelnut quantification see Berihuete & Antolín in press). For this reason, it has been considered necessary to develop suitable quantitative methods for a proper prosecution of our goals, especially concerning economically important taxa like cereals, acorns, hazelnuts and strawberry tree fruits. At the same time, these numeric descriptions have been done in enough detail so that these data can be quantified through other systems, so as to facilitate the comparison with other sites or regions. In order to make this possible, the final number of MNI was not introduced into the database, but only calculated and presented in the final tables of results.
The proposed methods usually imply some processing of the data, which should not be a problem when having adequate databases that can perform the desired calculations automatically. Unfortunately this is not yet available and extra time has been dedicated to the obtention of the MNI per taxon and per sample.
3.2.6.1. The calculation of the CU and the MNI
Several simple formulae were designed for the calculation of the CU and MNI of those taxa which were more frequent and which posed more problems for an exact quantification. A summary table is presented in Fig. 3.31. In nearly all cases, the total number of items (NR) has been recorded, since this is the most basic description. Then, an MNI is calculated.
3.2.6.1.1. Cereal grain and chaff
The quantification of charred cereal grain follows the method that we already presented elsewhere (Antolín
& Buxó 2011c), while the quantification of chaff and straw follows that proposed by G. Jones (1987; 1990) and others (Hillman et al. 1996).
3.2.6.1.2. Hazelnut shells
Archaeobotanists and archaeologists have quantified hazelnut shells in very different ways (volume, weight, number of remains, number of remains in the 2 mm fraction, number of fragments with basal part, etc.). A recent experimental evaluation of several methods showed that some of these do not produce a reliable MNI, while those dealing with weight are only applicable within a single site and only in the case when whole or half hazelnut shells are preserved (charred or dried) (which is rare) (Berihuete & Antolín in press). The formula that seems to give a more accurate MNI requires counting each identifiable item and record separately items below 4 mm2 (type 1). The total number of type 1 fragments is divided by 2 and then the result is added to the total number of fragments above 4 mm2 (type 2+3). The resulting number is divided by 8. This method seems to produce a relatively good MNI, especially among fragmented
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assemblages, which is our case. Among extremely well-preserved large assemblages of hazelnuts, establishing an average weight per fruit by weighting full or half nuts and then weighting the rest of the fragments and produce an MNI is a time-saving and reliable method (McComb & Simpson 1999).
TAXON OR
The largest number among TA/TE/TM + the largest number among LV/LD + LVD/2 + complete grains counted when no type 2 are found, and only counted as 1, no matter the number of fragments)
Rest of the taxa (CU)
Fr. type 2 + complete seed or fruit (fr. type 1 are counted when no type 2 are found, and only counted as 1, no matter the number of fragments)
Fig. 3.31. Summary table for the methods of calculation of the MNI per taxon or type of remain. For a description of type 1,type 2 and type 3 see Fig. 3.30.
3.2.6.1.3. Acorns: kernels, pericarp fragments and bases
Different parts of the acorn have been recovered in our samples, mainly cotyledon fragments, fragments of pericarp and acorn bases. Usually, cotyledon fragments are found in charred state, while fragments of pericarp or acorn bases are most commonly recovered in waterlogged state. Quite the opposite, several parts of the acorn appeared in the same sample when waterlogged conditions were present. In such cases, the higher CU obtained per type of fruit part was the one that was finally taken to quantify acorn remains from