| Methodology
Although there are many successful studies employing aDNA analysis, numerous difficulties and methodological problems still arise. The PCR technology is extremely sensitive and can be easily affected by contamination from nonrelevant DNA material. The source of contamination may be other personnel working in the field and laboratory or microorganisms such as bacteria. Another problem is the presence of inhibitors of unknown origin in aDNA extracts that interfere with the PCR reaction.14 In our laboratories, all work is routinely carried out using rooms, equipment, and reagents kept only for aDNA analysis. All personnel wear masks and sterile gloves to minimize contamination, and extensive controls are routinely used in all stages of DNA extraction and amplification. Specimens are thoroughly cleaned before sampling, and only sterile instruments that have been exposed to ultraviolet light to destroy DNA are used. Approaches have been developed to overcome the inhibitor effect, either through dilution of the inhibitor prior to PCR15 or alternate purification techniques. Contamination by contemporary human DNA will not pose a serious problem to this study because it is easy to differentiate the contaminating human DNA from the animal DNA obtained from the parchments. The aDNA obtained from the parchment fragments may help answer some interesting questions like the following:
What species of animals were used for parchment production? Currently it is thought that most of the scrolls were written on goat- or sheepskins, but variations in texture, color, thickness, and follicle number and distribution in the surviving parchments may indicate that other skins were also used. On the basis of microscopic examination of the distribution of hair follicles remaining in the parchment fragments, Ryder 16 was able to determine four different groups that could have been the possible species of origin for twenty samples of parchment from the Dead Sea area. He determined that one sample group derived from calf, one from a fine-wooled sheep, one from a medium-wooled sheep, and one from a hairy animal that could have been either a sheep or a goat. However, the exact species identification is impossible using only microscopic examination.It is likely that scrolls destined to contain religious writings were produced from ritually clean animals. According to Maimonides, "A scroll of the Law or phylacteries written on skins not expressly tanned for those purposed, is unfit for use." 17 Evidence from biblical sources and from at least one of the Judean desert scrolls (Temple Scroll) shows that very strict requirements were placed on the purity of animal skins. In particular, the skins brought into the temple or the temple city had extra requirements placed on their origin and preparation. According to Yadin, these skins had to be not only pure but "entirely holy and pure."18 In the Temple Scroll this requirement is stressed:Skin, even if it was made from the hide of a clean animal, unless the animal had been sacrificed in the Temple [should not be brought to the Temple city]. Such ordinary skins are, indeed, clean for the need of all labour in other cities, but "into the city of my temple they shall not bring [them]." 19Some of the parchments used at Qumran may have had less strict requirements for cleanliness and purity applied to them. It was therefore possible to use skins from species of animals that were clean, but not necessarily ritually pure and used for sacrifice in the temple. These clean, but not temple-city-worthy animals could have included a number of animal species such as gazelle, ibex, dishon, or deer. By identifying the species of animal used for the production of a specific parchment, it may be possible to postulate a hierarchy of importance for the different manuscripts. Some would have been intended for use in the temple or synagogue and other important sites within the temple city or community, and others may have had lesser religious significance.
How many different manuscripts are represented in the collection of fragments at the Rockefeller and Israel museums? Unfortunately, most of the recovered parchment material is quite fragmented, making it difficult to establish physically contiguous pieces of manuscripts. It is estimated that the approximately ten thousand fragments can be grouped into perhaps eight hundred different manuscripts, and it would be of tremendous value to be able to determine exactly which fragments belong together. Obtaining DNA signatures unique to each manuscript will make it possible to sort out the physical relationships of scroll fragments. Such information should prove particularly useful in sorting out the huge number of small fragments that cannot be confidently grouped on the basis of fragment shape, style of handwriting, or text, and it could provide unique insights into the subsequent interpretation of the scrolls.
Which fragments can be grouped together as originating from the same manuscript because they are from identical or closely related parchments? Because individual animals can be identified by their unique genetic signature, it is theoretically possible to identify the unique origin of each of the parchment fragments based on their genetic information. Using the techniques of aDNA analysis, fragments belonging to the same or closely related skins can be grouped together. This could assist both in the reconstruction of manuscripts and in the verification of assemblies already made. Introduction | Section 1 | Section 2 | Results and Notes |
