Planning

An overview of planning that includes long-term curation serves as a useful guide (e.g., Childs and Benden Reference Childs and Benden2017), but burial-specific concerns include specialized laws, analyses, documentation, materials and space, communication, costs, and health. First, what regulations and laws govern the discovery of burials, and how will personnel be trained on how to avoid or how to excavate burials when discovered unexpectedly? Second, each bioarchaeologist needs to design his or her data collection methods. While a burial form serves as a guide for the information to be collected, it must be supplemented by photos, drawings, notes, and other documentation. More important, the specialist can guide the bioarchaeological research strategy because DNA analyses, direct radiocarbon dating of burials, and isotopic reconstructions of migration and diet are increasingly common. The bioarchaeologist, conservationist, or other researcher also will have specialized resource needs, such as protected space for analysis of fragile skeletal remains, appropriate lighting, trained field staff, and materials that are unavailable near the field location. For example, the potential discovery of a tomb might require chemicals that are not locally available to collect environmental pollen samples or recover fragile offerings (Cameron McNeil, personal communication 2018). Another decision relates to use of digital or paper references where electricity or internet services may be unreliable. Long-term planning is key, as human remains frequently are studied years after the excavations occur and by multiple researchers with distinct questions (e.g., Weiss-Krejci Reference Weiss-Krejci, Agarwal and Glencross2011).

Communication includes identifying interested parties such as descendant communities and local stakeholders and their role in the project, even when not required by law. Their participation may be limited to sharing project results or extend to contributing to research design or even funding. Nearly 30 years after the Native American Graves Protection and Repatriation Act's implementation, it is still common to hear stories about excavations that occurred in advance of notification of Native American tribal representatives even where mandated by state and/or federal laws. It also can take years of investment and planning to organize community archaeology fairs, produce materials for tour guides, and construct long-term storage facilities or museum exhibits and/or the museums themselves. A communication plan is recommended among project staff as well. If the bioarchaeologist is not on site, s/he should be consulted as new discoveries are made for better data recovery. This includes a plan for reports, publication, and data sharing so specialists’ data is available to project members but are not simply relegated to appendices or acknowledgments.

The costs of excavating burials can add up quickly, since excavations may include more burials than expected or complex burial contexts with fragile goods that require specialized care, export and repatriation expenses, and lab payments for chemical analyses. At a minimum, the bioarchaeologist can estimate the number of hours each burial requires so that budgets—which vary by country—include a real estimate of the money and hours needed. Excavating human remains is an investment: finding personnel with a long-term interest in the project is a better strategy than using a shifting pool of students or consultants that changes each year. This also allows for the development of a better interpretive framework for burial populations that result from unintentional discoveries rather than a specific research design (see Martin et al. Reference Martin, Harrod and Pérez2013 for a good guide).

A final but important cost consideration is planning for health. Excavations in historic cemeteries should consider the possibility of arsenic and heavy metal contamination and the potential for bodies (vs. skeletonized remains) in sealed coffins (Jonker and Olivier Reference Jonker and Olivier2012; Konefes and McGee Reference Konefes, McGee, Poirier and Feder2001; Meyers et al. Reference Meyers, Borstel, Breetzke and Holt1998). In the Maya region, burials may present hazards beyond dangers presented by normal wildlife such as dogs, bees, snakes, or cows. Excavations of burials in caves or other closed spaces may expose excavators to histoplasmosis or similar diseases. Tombs with hematite or cinnabar (or mercury) may require special protocols. Burials more than 100 years old generally present fewer risks of toxins or pathogens than more recent ones (Antoine and Taylor Reference Antoine, Taylor, Fletcher, Antoine and Hill2014), but a thorough consideration of both modern and ancient health risks is needed.

Excavation: Exposure and Screening

The initial goal of the excavation is to expose the skeletal remains, minimizing contact with the bones and exposure to environmental changes such as direct sunlight, heat, or humidity. The remains are not cleaned until they are ready to map and photograph. Inexpensive wood or plastic tools such as bamboo skewers may be as useful as specialty supplies to remove dirt around bones, including nonhuman fauna and fragile artifacts, without dislodging or damaging them.

I map the burial not as a single deposit but as a feature where each bone or bone cluster is documented. Each bone is numbered sequentially (1, 2, 3, etc.), which is useful for nonspecialists who may incorrectly identify bones that are not in anatomical position. Burials in the Maya region frequently contain the remains of more than one individual, where graves are reentered or disturbed and skeletal remains are commingled. Each bone may be marked with a numbered marker, available from biological supply and forensic companies, to serve as a reminder of its location as the excavation proceeds.

Screen size affects the recovery of bone, especially in burials of juveniles or fragmentary remains. Wet or dry screening depends on availability of water and the preservation of the bone. Wet screening may damage fragile bone, which can be mitigated to some extent by maintaining a constant environment for the bone (i.e., not letting bone dry out then re-wetting it). Wet screening using a tulle fabric over ⅛-inch mesh is time-consuming but provides good recovery of the bone fragments of infants or perinates. I screen matrix separately for each bone/bone cluster since even small fragments may contain useful information on the extent or location of pathologies. This is useful in understanding burial context as well. We recovered most fragments from an incised deer antler bloodletting implement underneath the highly fragmented rib cage of a prone burial by screening the upper chest area separately from the rest of the base of the grave.

Drawings and Photographs

Drawings contain different information than photographs, in which all bones are not visible and may be hard to distinguish from the surrounding matrix. The three-dimensional location (X, Y, Z coordinates) of each bone or cluster of bones is recorded using either manual or digital methods. Multiple elevations are useful if there is a change of more than 5 cm in elevation of the same bone. In situ measurements are part of the drawing process, and many references offer detailed procedures for recovery and analysis (e.g., Bass Reference Bass2005; Steele and Bramblett Reference Steele and Bramblett1988; White and Folkens Reference White and Folkens2005; see also Baker et al. Reference Baker, Dupras, Tocheri and Wheeler2006; Dupras et al. Reference Dupras, Schultz, Wheeler and Williams2011; Scheuer et al. Reference Scheuer, Black and Schaefer2010; Ubelaker Reference Ubelaker1978).

An artist's drawing board works better than a standard clipboard, and metric graph paper should be large enough for a 1:5 scale for an adult burial or a 1:2 scale for an infant or close-up drawing of a hand or foot. While 1:10 is considered acceptable for burial documentation, more space may be desired for disturbed burials, commingled remains, or other complex burials. Writing on transparencies placed over graph paper works well to record elevations (top and bottom) and/or bone numbers, as well as grave goods identified with unique special find numbers.

As photogrammetry and automated mapping techniques become more popular, it is important to consider how they may complement rather than replace traditional mapping techniques (Novotny Reference Novotny2019). Techniques such as reflectance transformation imaging may capture more detail than a close-up photo, and three-dimensional models can provide spectacular tomb reconstructions (Berggren et al. Reference Berggren, Dell'Unto, Forte, Haddow, Hodder, Issavi, Lercari, Mazzucato, Mickel and Taylor2014; De Reu et al. Reference De Reu, De Smedt, Herremans, Van Meirvenne, Laloo and De Clercq2014; DiBiasie-Sammons Reference DiBiasie-Sammons2018). Digital mapping also can produce georeferenced ortho-images that can be imported directly into a geographic information system (GIS), potentially creating more accurate images and reducing drawing time.

A separate drawing and set of photographs are made for each level of bones before they are removed. Most burials in the Maya region will have at minimum two to three layers of skeletal remains, although Burial 11 had six. Numbering the bones even when their identification seems obvious is important. A body may appear to be articulated in anatomical position, but only an experienced osteologist might note that a bone is in the wrong place, as bones were often moved in antiquity as graves were reentered (Nilsson Stutz Reference Nilsson Stutz2003, Reference Nilsson Stutz, McCarten, Schulting, Warren and Woodman2008).

Example: Burial 11 Taphonomic Profile

Figure 2 shows a digitized plan view of Burial 11, with bones critical to understanding the body's original position and subsequent decomposition labeled. The inset shows an interpretation of the body position. The exact position would not be interpretable until more than 60 bones were mapped and documented in three dimensions. The small grave (60 × 60 cm wide and 25 cm deep) held a semi-flexed individual who was bent over rather than seated upright. The pit was not sealed, so cobble fill from the floor constructed above it collapsed into the pit as the body decomposed, contributing to the postmortem movement of the cranium (Freiwald, Mixter, and Billstrand Reference Freiwald, Mixter and Billstrand2014:102). None of the limb bones were sufficiently complete to estimate stature, even using partial bones (i.e., Steele and Bramblett Reference Steele and Bramblett1988), but an in situ measurement of the right ulna suggests a height of 5′6″ to 5′9″.

FIGURE 2.

Key bones mapped in six burial layers, resulting in an interpretation of the body position (inset). Image modified after drawings by David Mixter digitized by Nicholas Billstrand.

The legs were semi-flexed, and the arms were placed at a 90-degree angle across the body. Long-bone preservation was good (average score “1” for completeness, “0” for surface preservation [Buikstra and Ubelaker Reference Buikstra and Ubelaker1994]). However, the loose fill may have allowed more decomposition at the top of the grave, resulting in long bones consisting only of shafts and only partial mandibular, frontal, and temporal portions of the skull.

Recovery and Transport

Burials usually require multiple days to expose, document, and remove, depending on the complexity of the burial, the number of individuals, and the burial context. However, many circumstances require excavations to occur more quickly. For example, in remote locations, the threat of looting can pose a real physical danger to project members when whole vessels, jade, or other valuables are present (or perceived to be). These circumstances may require rapid excavation, as do tropical storms or hurricanes if excavations occur during the rainy season.

After the drawings and photographs are complete for each burial layer, the bones and associated matrix can be gently dislodged and placed in foil in their original position so that I can complete the excavation in the lab. Because burials in the Maya region are oriented to specific directions, both the orientation and physical position of the bone are recorded. If a nonspecialist is assisting, marking the foil with the bone position and a north arrow (orientation) is sufficient to capture the information for the bioarchaeologist. This also is useful to hold highly fragmented bones in place until they can be analyzed, as the foil and soil matrix offer support for bones and maintain constant environmental conditions (i.e., does not let the bone dry too quickly).

Removing fragmented bones and the associated matrix in foil and completing the excavation in the lab retains the same information as the use of preservatives or consolidants, avoiding the lengthy cleaning process required to remove them (but see Beaubien Reference Beaubien2019 for alternative procedures). More important, this avoids potential contamination that could affect aDNA, isotope, and protein analyses. For example, France and colleagues (Reference France, Giaccai and Doney2015) found that Paraloid B-72 and Butvar® B-79, common consolidants, affected oxygen isotope values in some tissues but left others unaltered. Diagenesis is a critical concern for isotope geochemistry, but there often is a disconnect between these analyses and excavation and lab procedures in museum settings.

Analysis should occur within a short period of time to avoid damage from fungi, molds, or dampness. However, if a specialist is not present, more information may be lost by processing the skeletal remains than by storing them until in-depth analysis is possible during subsequent field seasons. Burials discovered at the end of a field season might be looted if left in situ, leaving excavators little choice but to recover and store the materials even if a specialist is not present. In this case, bones may be dried before storage. Potential diagenetic contamination from materials used to store the bones is not well understood, so sterile bags such as those used for DNA samples are another possible storage technique.

Laboratory Analysis

The bioarchaeologist may complete the final stage of excavation in the lab by excavating the bones removed in foil. Ideally, a specialist can be present to record the information in the field. If not, each bone's orientation and position should be captured as the bones are removed and placed in foil. The bioarchaeologist can use the burial drawings and excavation notes as a guide to reconstruct the taphonomic profile of the burial before beginning the osteological analysis. For articulated burials, identifying the bone position and orientation is straightforward. However, precise bone positions are informative: the articulation of labile hand bones can be used to identify bundled or wrapped bodies or open or filled-in graves (Duday et al. Reference Duday, Cipriani and Pearce2009). In climates where fragile hand bones are poorly preserved, the positions of the lower arm bones might reveal the original placement of the hands.

Most projects likely have washing procedures that include using fine mesh to collect tiny bone fragments, sieving the water after processing each bone or context (e.g., Bass Reference Bass2005). A light brush may work for cleaning in dry climates, but in the tropics, the bones may be rinsed if they are not overly friable. If the bones are held together with matrix in the medullary cavity, recording measurements of the whole or partial bone should precede washing.

Recording Osteological Information

Most osteologists working in North America use variations of the forms published by Buikstra and Ubelaker (Reference Buikstra and Ubelaker1994), modified paper forms (ASM 2011), or the Smithsonian's Osteoware (https://osteoware.si.edu/) and other digital recording systems (see Osterholtz Reference Osterholtz2019). Researchers commonly supplement these forms with data collection methods of their own design, especially in the case of complex burial practices or taphonomy. I draw from zooarchaeological and forensic sciences, which requires quantification of bone assemblages (counts and weights for each element) and documents the type(s) of animal, natural, and human activities that affected each bone fragment (Lyman Reference Lyman2001; Nawrocki Reference Nawrocki, Blau and Ubelaker2011; Redding et al. Reference Redding, Zeder, McArdle, Meadow and Zeder1978). Counting and weighing each bone documents fragmentation, which in turn provides information on postmortem processes and the effectiveness of recovery, transport, and ongoing curation. Counting and weighing the fragments from each bone element also serves as a backup provenience in place of writing on the bone or gluing labels to it, which over time can damage the bone and is disallowed by many indigenous or descendant communities.

Long-Term Storage

Curation standards differ in tropical climates. Use of any kind of paper product, even acid-free, can result in collection management disasters. If (when) materials become wet, mold and fungus can destroy the containers, tags with context information, and eventually the bones. In general, dry bone fragments may be stored in polyethylene curatorial 2- or 4-ply sealed plastic bags. Write-on-white bags and permanent marker work well to record provenience on the exterior of bags, and Tyvek tags work well for a duplicate interior tag, including the number assigned to the bone in the drawing. While it is initially more work to write tags than to use preprinted paper, high-quality materials are a good investment. Storing dried osseous materials in sealed bags creates a microenvironment that reduces the effect of changes in humidity even without climate-controlled facilities. Placing the sealed plastic bags in airtight plastic containers with nondegradable padding protects the bones and maintains a relatively constant environment that minimizes further deterioration.

A related challenge is the increasing use of electronic data collection systems to record data, such as tablets or GIS for mapping and laptops for digital data entry. Replacing paper forms and traditional photographs with electronic records solves problems of accessibility and accuracy in data entry and provides faster, better burial documentation (Novotny Reference Novotny2019; Osterholtz Reference Osterholtz2019; Wrobel Reference Wrobel, Biggs and Hair2019). New technology, however, also creates novel challenges with hardware and software failures and potential data loss. Duplicate paper records in sealed containers attach provenience to the collections and retain all original records in a single location (vs. with each analyst). Reuse of existing collections is increasingly important as new bioarchaeological techniques are developed, existing ones are improved, and collections are studied decades after excavation (Roberts and Mays Reference Roberts and Mays2011; Weiss-Krejci Reference Weiss-Krejci, Agarwal and Glencross2011; Wrobel Reference Wrobel, Biggs and Hair2019).