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Scientific Working Group for Forensic Anthropology (SWGANTH)

Ancestry Assessment

Issue Date: 06/12/2013

Revision: 0

Ancestry Assessment

1.0 Principle, Spirit, and Intent 

Skeletal remains should be analyzed in a systematic manner for the purpose of assessing ancestry 

that may be relevant to human identification. The most appropriate technique(s) for assessing 

ancestry should be reliably and objectively applied. Methods should be documented to enable 

replication and verification. 

2.0 Purpose and Scope 

The following guidelines outline procedures for the assessment of ancestry from human skeletal 

remains. Many different methods are used in field and laboratory settings and may be population 

dependent. The intent is not to endorse one particular method, rather to establish valid 

assessment of ancestry. 

Practitioners of forensic anthropology should implement these guidelines to the fullest extent as 

applicable, practical, and appropriate. In the absence of specific guidelines or procedures or in 

the case of conflicting procedures, the principle, spirit and intent should be met. 

3.0 General Principles

Ancestry refers to the geographic region and/or the ancestral origin of a particular population 

group. Ancestry assessment of skeletal remains is important because it provides meta-data that 

can be used to narrow the list of potential matches from missing person’s reports for DNA 

comparison, radiography comparison, or some other form of positive identification. Additionally, 

ancestry assessment will often affect estimates of other aspects of the biological profile.

Skeletal morphology is polygenic, reflecting genetic and environmental factors, and is highly 

heritable. Fundamentals of transmission genetics, evolutionary theory, quantitative variation, and 

human biological variation all provide support that skeletal morphology can be used to assess 

population relationships, even when considering environmental variation. Statistical methods of 

classification provide further mechanisms for assessing the relationship of an unknown 

individual (i.e. forensic anthropology case) to multiple reference groups for the purposes of 

ancestry assessment.
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3.1 Human Variation 

Modern human populations show more similarities than differences. Using genetic data or 

skeletal morphology, typically 85% of world-wide variation is found within populations and 

15% between populations. Ancestry assessment involves classification and statistical methods 

and can maximize between-group variation to improve classification rates. 

3.2 Classification 

Because of the relatively high concordance between social race categories (e.g. U.S. Census 

Bureau race and ethnic categories) and skeletal morphology in the United States, social race 

categories can be used as a descriptor of group membership when writing a forensic report. In 

most forensic cases in the US, race will be a useful category to narrow down possible 

identifications, but further refinements may be necessary. For example, an ancestry of "East 

Asian" may not be specific or precise enough in some cases and distinctions between 

Vietnamese, Japanese, or Korean may be desirable. Depending on the country and region, local 

or national social race and/or ethnic categories may have low or high correlation to certain 

biological measures. When reporting a classification, do not state results in unequivocal terms. 

Even when probabilities indicate group membership is highly likely, it can still be incorrect in 

social terms because of the imperfect correlation between social race and biology. Biological 

answers do not always, no matter how strong, reflect the discrete race classification. 

When craniometric data or trait frequencies for groups are assessed, there is no distinctive single 

trait that uniquely identifies any human group. Individuals may display skeletal traits that are 

“diagnostic” of different groups – and rather than concluding mixed ancestry, knowing and 

understanding the fundamentals of quantitative variation, the population frequencies of those 

traits, and the population structure and history of the groups in the analysis will aid in 

interpretation. 

Complex groups (e.g. Hispanic) and individuals are expected to be difficult to correctly classify. 

However, using morphometric and morphological criteria with statistical methods should

provide far better classification than random allocation. 

4.0 Approaches

Reference samples/groups should be critically evaluated in terms of sample size, temporal 

period, geographic location, ethnicity, language, and other cultural parameters and activities such 

as dental modification. Sample sizes should be large enough to represent the natural variability 

present in all populations. Due to secular changes, reference samples should be comprised of 

forensically relevant individuals.

The statistical methods used provide measures of uncertainty in an overall classification 

(assessing the possibility that an ancestry can be correctly assessed) and to specific 

classifications (the probability that a correct classification into one group is far more probable 
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than classification into a different group). There are no clear-cut or unambiguous indicators of 

ancestry. Rather, groups show differences in frequencies of traits or in means of measurements. 

Selection and application of ancestry assessment methods depend on the skeletal elements 

available for examination, their condition, and the age and sex of the individual being examined. 

Analysis of skeletal remains for ancestry may involve different or multiple approaches, including 

morphological and metric traits. Generally these traits are analyzed separately, but they may also 

be analyzed together using certain statistical methods. 

A single trait can rarely separate any two groups and the accuracy will be improved when using 

more traits. Also, there may be traits that suggest conflicting ancestries, but in a statistical 

classification method they will be properly weighted. Therefore, all traits of interest should be 

recorded. The most-often used statistical method is discriminant function analysis, but additional 

methods (e.g., nearest neighbor analysis and kernel probability density analysis) can be used and 

may be more appropriate than discriminant function analysis. Also, statistical methods provide 

ways to express uncertainty, for example, using posterior probabilities. For further details see the

SWGANTH guidelines for Statistical Methods. 

4.1 Morphological Traits 

Morphological (non-metric) traits include discrete and morphoscopic traits/features of the 

skeleton, particularly the cranium, mandible, and teeth. Many non-metric traits are binary in 

nature, and recorded as present/absent. Morphoscopic traits, in comparison, represent ordinal 

grades of expression. When scoring non-metric traits, each trait should be scored independently

of what the trait has traditionally implied for ancestry. For instance, a postbregmatic depression 

has traditionally implied African ancestry, although it is present in other groups. 

Morphological traits can be used in ancestry assessment with 1) appropriate reference groups, 2) 

clear trait descriptions, and 3) appropriate statistical methods of classification. 

4.2 Measurements

Measurements used in ancestry assessment generally involve cranial size and shape. Postcrania 

will also provide robust estimates. Appropriate measuring instruments, standards and/or software 

should be employed. As with morphological traits, multiple measurements and multivariate 

statistical techniques provide greater validity in ancestry assessments. 

Measurements can be used in ancestry assessment with 1) appropriate reference groups, 2) clear 

measurement definitions, and 3) appropriate statistical methods of classification. 

5.0 Best Practices

The following practices are recommended for ancestry assessment: 
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Ancestry assessment should be made independently of suspected or presumptive 

identifications. 

Use methods based on large appropriate sex- and period-specific standards/samples with 

sufficient sample sizes and with objective ways of measuring and recording traits. 

Measurements and non-metric observations should always be recorded, even if samples 

for DNA analyses will be taken. 

Use adequate traits with appropriate statistical methods of classification. Express 

probability of certainty when reporting ancestry assessments, especially because ancestry 

assessments should never be given with 100% certainty as expressed in posterior 

probabilities. 

Use all appropriate and available groups for your case, but remember that the most 

appropriate reference samples may be unavailable for analysis. 

Know metric or non-metric trait definitions and be sure to understand how to score and 

record them. 

Understand the appropriate statistical methods employed in ancestry assessment and

understand the interpretation of the results. 

Use terminology that is appropriate and widely accepted within the local vernacular, e.g. 

these remains likely represent a person who self- identified as Black during life. 

When comparing against reference groups, if the skeleton is complete and sex is 

unambiguous, perform a sex specific analysis, (i.e. if skeleton is clearly male, compare 

against male reference groups only). 

Anonymized raw data should be submitted to open-access anthropological data 

repositories to support future research and methodological improvement. 

6.0 Additional Considerations 

Pathological or taphonomic alterations may preclude the utilization of specific ancestry 

assessment techniques. 

A major assumption in classifying an individual is that the unidentified individual comes from

one of the populations represented by the reference groups. If one uses techniques for classifying 

an individual into two groups, for example, White and Black Americans, the technique can only 

classify into one of those groups even if the individual does not belong to either group.

7.0 Unacceptable Practices 

The following practices are considered unacceptable and should be avoided when assessing 

ancestry.

Basing conclusions on faulty samples (small, inappropriate temporal period, irrelevant 

geographic origins, arbitrary or uncertain classifications in reference groups). 

Basing conclusions on one or two morphological traits. 

Basing conclusions on methods that have not been validated.