Side Determination
Definition
The osteological process of assigning a paired skeletal element (clavicle, humerus, femur, rib, os coxae, etc.) to the left or right side of the body using asymmetric morphological features that differ between the two sides. Critical for skeletal inventory and minimum-number-of-individuals calculations.
- Applies to
- Paired skeletal elements: clavicle, humerus, femur, rib, os coxae, etc.
- Basis
- Asymmetric morphological features differing between left and right
- Purpose
- Skeletal inventory and minimum-number-of-individuals calculation
- Error risk
- Fragmentary or juvenile elements are harder to side correctly
Common questions
Why does getting side determination wrong matter for a minimum-number-of-individuals count?+
If a left and right femur from the same skeleton are mistakenly both recorded as, say, left-side elements, they will be counted as coming from two different people rather than one, inflating the estimated number of individuals present, which matters directly in mass grave or commingled remains cases.
Does side determination require an intact bone, or can it be done on fragments?+
It is most reliable on intact or near-complete elements where the diagnostic landmarks are present. Heavily fragmented pieces lacking those landmarks may be un-sideable, and forcing a side call on insufficient morphology risks the counting error side determination is meant to prevent.
Related terms
- Cortical Index
- The ratio of total cortical bone area to total bone cross-sectional area at a defined midshaft location. Used in fragment identification to...
- Fragment Identification
- The assignment of a bone fragment to a specific skeletal element (rib, long-bone shaft, vertebral arch, cranial vault, etc.) and anatomical region,...
- Haversian Canal
- The central vascular channel of an osteon, carrying blood vessels and nerves through the cortical bone. Diameter 20-70 µm in human bone....
- Minimum Number of Individuals (MNI)
- The smallest number of distinct individuals required to account for all skeletal elements present in an assemblage. Determined by identifying the element...
- Neural Arch
- The posterior bony arch of a vertebra, formed by two pedicles and two laminae meeting at the spinous process. In foetal and...
- Osteon
- The basic structural unit of cortical bone: a set of concentric lamellae surrounding a central Haversian canal. Human secondary osteons are roughly...
- Owsley-Mann Protocol
- The fragment identification and triage methodology developed by Douglas Owsley (Smithsonian Institution) and Robert Mann (DPAA) for systematically assigning commingled bone fragments...
- Plexiform Bone
- A microstructural pattern found in the cortical bone of large rapid-growth mammals (bovids, horses, deer) characterised by alternating layers of woven bone...
- Species Confirmation (DNA)
- PCR-based or sequencing-based confirmation that a bone fragment is of human (Homo sapiens) origin, using human-specific primer sequences or mitochondrial cytochrome b...