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Section: Technical Report [a] Laboratory for Human Evolutionary Studies, Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
b Curator of Biological Anthropology Collection, Phoebe Hearst Museum of Anthropology, University of California, Berkeley, CA 94720, USA Museum collections are often the only feasible source of human skeletal material for ancient DNA work. The benefits of DNA analysis have to be weighed against the scientific costs of alteration and loss of these irreplaceable resources. The article presents guidelines for the use of skeletal collections, the objective being to limit destruction and thereby preserve remains for future study. Keywords: Ancient DNA, Bones, Museum specimens, Reburial, Sampling guidelines Skeletal collections are precious, irreplaceable resources. For many research problems, such as ancient DNA work, it is practically impossible for human skeletal remains to be collected in the field. This makes museum collections the only feasible source of material (Graves and Braun, 1992). For this reason it is imperative to weigh carefully the value of potential DNA sequence data against the scientific costs of specimen alteration and loss. A number of measures can be taken to limit the destruction of skeletal tissue during DNA extraction, thereby preserving remains for ongoing study by osteologists and archaeologists. The following guidelines are based on the authors' experience in assessing skeletal material from the Phoebe Hearst Museum of Anthropology at the University of California, Berkeley. The Museum, like many others, faces a new research- and technology-driven demand for human remains in its care. In order to evaluate such requests, we have turned for inspiration to the excellent editorial by Paabo et al. (1992). Here we will cover considerations specific to the use of skeletal collections. Of course, each museum's osteological collection is unique and has special use constraints. What follows is a set of observations that should apply across a wide range of museum skeletal collections, both human and non-human. USE OF UNPROVENIENCED MATERIAL Virtually every museum, or the academic department associated with it, has skeletal material of unknown origin, often in the form of a teaching collection. This material typically lacks proper provenience (e.g. records as to where it came from), and thus is of limited use to archaeologists. These unprovenienced specimens, while very important for training future osteologists, are not as valuable as cataloged archaeological materials. In many cases, we suggest that would-be ancient DNA investigators perfect their techniques by using unprovenienced skeletal remains. Then, if the pilot study succeeds, an application for use of archaeological materials is supported. This extra step is of value to all parties as it provides the opportunity to conduct a trial run of protocols, contamination controls, and so forth before using irreplaceable archaeological specimens. It is particularly beneficial to the museum because it provides a measure of the sincerity, care, and potential of the applicants. The use of unprovenienced material allows investigators without a track record in ancient DNA to demonstrate their competence without risking museum specimens. SELECTION OF SPECIMENS Just as an osteologist interested in working with DNA would be well advised to consult with a molecular biologist, the molecular biologist contemplating a project involving the extraction of DNA from skeletal material would do well to seek help from a mammalogist, physical anthropologist, or zooarchaeologist specializing in osteology. Osteologists are the primary users of most skeletal collections, and therefore have the knowledge, experience and training needed to help ancient DNA workers identify, prepare and isolate the appropriate portions of the appropriate skeletons. A professional osteologist, preferably one familiar with the particular collection, should be consulted about all phases of the project involving the actual bones before an application to the relevant repository is made. The selection of the exact museum material to use will depend on the nature of the research question, methodology and the museum's restrictions. Often the current needs of the ancient DNA investigator and the probable future needs of osteologists are not mutually exclusive. Unless an osteologist is consulted, however, indications of pathology or cut marks (for example) may well go unnoticed. Thus an osteologically or archaeologically very important bone may unknowingly be destroyed even though another, less valuable, bone might have served the ancient DNA investigator equally well. The relative potential osteological value of particular bones and specimens should be assessed by an osteologist and archaeologist, and seriously considered in the selection of the material to be used. Unfortunately, museums often lack staff osteologists or archaeologists due to limited budgets: In such cases, the DNA project must assume responsibility for securing specialist input, and the museum should carefully weigh the opinions and recommendations of these specialists. This will often require the museum to engage independent, outside expertise to evaluate the assessments of the DNA project's osteologist and archaeologist. METHODS FOR PRESERVING MORPHOLOGY When analyzing any skeletal material, a primary concern should be to minimize the amount of morphological information destroyed. In all cases, a permanent record of the morphology to be destroyed or altered should be made. Molding and casting of the bone prior to destructive analysis is the best method, as it provides a permanent, three-dimensional record of the specimen to which future researchers can refer (Smith and Latimer, 1989). Despite the low cost and ease of casting, our survey of ancient DNA literature found no mention of it. Even in a report which addresses the preservation of modern skeletal material used in forensic DNA analysis (Smith et al., 1993), casting is not discussed. If molding and casting of skeletal material prior to destruction is not standard practice, it should be. Numerous museums and anthropology departments have molding and casting facilities available, as well as workers familiar with such methods. Another obvious method for archiving morphological information is photography. By itself, however, photography cannot provide a complete record of morphology. The combination of photographs with casts provides excellent documentation, as photographs often reveal minute details and colorations which are lost in a cast. To be of use to future investigators, photographs must be of high quality (White, 1991 and the references therein). Most museums have personnel skilled in scientific photography who could be consulted. Advances in technology have made other methods of archiving morphology practical (Kappelman, 1993
Sadler, 1993). Notable among these are computerized axial tomography and laser scanning. Any new methods of preserving information, as well as existing ones, should be evaluated with the potential future research needs of archaeologists and osteologists in mind. Documentation only preserves morphological information if it remains permanently accessible. To ensure availability, casts and photographs of the relevant specimens should be promptly deposited in the museum archives. Most museums have detailed record-keeping protocols to be followed. It should be immediately obvious to future researchers which specimens have been used for DNA analysis, where the archival material (photographs, casts, etc.) can be found, and where copies of the results and publications stemming from the DNA research are located. Problems of accessibility, durability, and storage space may be alleviated by computerization of the relevant records and images (Roberts and Rudgewick-Brown, 1991
Verano et al., 1993). FORMAL APPLICATION FOR DNA ANALYSIS OF SKELETAL MATERIAL The destructive analysis of museum-held skeletal remains obviously requires the prior approval of the curators. However, most museums have probably received few such requests and may not have an appropriate application procedure in place. To evaluate ancient DNA requests properly museums need to be provided with the following: A project description outlining the research problem and methodology, along with a timetable. Background information on ancient DNA and an indication of how the proposed project fits into the existing body of work. Since museum personnel might not closely follow developments in molecular biology, it may be helpful to include several of the better popular articles on ancient DNA. A list of materials requested and a description of the planned method of recording and archiving the specimens (see above). Any flexibility the project has as to the type and amount of material needed, and any potential alternative sources of material, should be indicated. A summary of research (past, ongoing and planned) involving the material requested, along with an evaluation of how the sampling will impact such work. The input of an osteologist and archaeologist familiar with the collection is needed for this. The curriculum vitaes of the research personnel, noting any prior work with ancient DNA, and a description of the laboratory to be used. Sources of funding for the work and a draft of a formal loan agreement (Paabo et al., 1992). THE 'REBURIAL' ISSUE AND ANCIENT DNA Recently, the existence of museum collections of Native Australian and American skeletal remains has been denounced by some members of the aboriginal communities. This so-called 'reburial' issue is of great concern to osteologists and archaeologists, as it threatens to destroy much information about the past. A number of important skeletal collections have already been lost and thus can never be the subject of further study (like DNA analysis). A fuller treatment of this issue is beyond the scope of this paper (for various perspectives see Ubelaker and Grant, 1989
Goldstein and Kintigh, 1990
Ubelaker, 1990
White, 1991
Meighan, 1992
Klesert and Powell, 1993). Ancient DNA researchers working with skeletal material should be aware of the United States federal legislation which imposes restrictions on the use of Native American skeletal material and threatens its continued curation (Public Law 101-601, November 16, 1990, 'Native American Graves Protection and Repatriation Act,' 101st Congress). Similar restrictions exist on research using Aboriginal skeletal material in Australia, though the laws and policies differ by state and by institution (Webb, 1987). Knowledge of the current local situation is of critical importance for those contemplating such research. The repatriation issue makes the proper treatment and handling of skeletal remains by all who work with them particularly important. As members of the scientific community engaged in studying the past by using skeletal material, there is arguably a moral and ethical obligation to become involved whenever skeletal remains in the public trust are threatened. Ancient DNA workers should realize that the entire field is dependent upon the continued availability of ancient remains. The wholesale destruction of such remains should therefore be a matter of great concern. References Goldstein, L. and Kintigh, K. (1990) Ethics and the reburial controversy, American Antiquity 55, 585-591. Graves, G. R. and Braun, M. J. (1992) Museums: storehouses of DNA?, Science 225, 1335-1336. Kappelman, J. (1993) Building an evolutionary database using digital imaging and animation software, Am. J. Phys. Anthropol. Meeting Supplement 16, 122. Klesert, A. L. and Powell, S. (1993) A perspective on ethics and the reburial controversy, American Antiquity 58, 348354. Meighan, C. W. (1992) Some scholars' views on reburial, American Antiquity 57, 704-710. Paabo, S., Wayne, R. and Thomas, R. (1992) On the use of museum collections for molecular genetic studies, Ancient DNA Newsletter 1, 4-5. Roberts, C. and Rudgewick-Brown, N. (1991) CD ROM imaging in osteoarchaeology, Int. J. Osteoarchaeol. 1, 141145. Sadler, L. L. (1993) Beyond CT: alternative high-resolution imaging techniques for capturing anatomical data, Am. J. Phys. Anthropol. Meeting Supplement 16, 171. Smith, B.C., Fisher, D. L., Weedn, V. W., Warnock, G. R. and Holland, M. M. (1993) A systematic approach to the sampling of dental DNA, J. Forens. Sci. 38, 1194-1209. Smith, J. and Latimer, B. (1989) A method for making threedimensional reproductions of bones and fossils, Kirtlandia: Cleveland Museum of Natural History 44, 3-16. Ubelaker, D. H. (1990) Importance to forensic science of permanent curation of museum collections of human skeletal remains, J. Forens. Sci. 35, 513. Ubelaker, D. H. and Grant, L. G. (1989) Human skeletal remains: preservation or reburial, Yearbook of Physical Anthropology 32, 260-287. Verano, J. W., Urcid, J., Byrd, B. S. and Frohlich, B. (1993) Documentation of human skeletal remains subject to repatriation: a view from the mall, Am. J. Phys. Anthropol. Meeting Supplement 16, 201. Webb, S. (1987) Reburying Australian skeletons, Antiquity 61, 292-296. White, T. D. (1991) Human Osteology, Academic Press: San Diego.
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