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Scientific Working Group for Forensic Anthropology (SWGANTH) 

Age Estimation 

Issue Date: 01/22/2013

Revision: 1

Age Estimation 

1.0 Principle, Spirit and Intent 

This section presents methods utilized in age estimation. Such methods are usually applied in 

forensic anthropology to estimate age at death in deceased individuals, especially skeletal 

remains, but aspects can also be applied to assessing age in living individuals. Estimates of age 

are important because they can be compared with antemortem records or other information to 

contribute to the identification process or help resolve other medico-legal issues, such as 

evaluation of age of living individuals in immigration cases. The methods should be employed 

with a spirit of scientific integrity: subjective interpretation should be limited, scientifically 

tested methods should be used, where possible, and method weaknesses and limitations should 

be communicated. 

2.0 Purpose and Scope 

Selection of methods to be employed in age estimation depends upon the materials available for 

examination, their condition and the age category of the individual. Analysis of fetal, infant, 

child, adolescent and adult remains may involve varied methodology, including gross 

examination, the use of radiographic techniques and histological approaches. These guidelines 

recommend approaches for estimating age depending on the age category. Practitioners of 

forensic anthropology should implement these guidelines to the fullest extent as applicable, 

practical, and appropriate. In the absence of specific guidelines or in the case of conflicting 

procedures, the principle, spirit and intent should be met. 

3.0 General Principles 

Age estimation involves first assessing physiological age and then attempting to correlate it with 

chronological age. The developmental or degenerative traits used as age standards undergo 

sequential chronological change. The traits represent the stages of physiological age for an 

individual. These traits are observed and documented in modern individuals of known 

chronological age, sex and ancestry. Correlations can be made between the traits that define 

physiological age and the chronological age of the known individuals, although these 

correlations are not perfect. If correlations are strong, this information can be extended to 

estimate the age of unknown individuals of similar sex and/or ancestry. Such applications 

assume that the process occurs in the same order and at the same rate in the unknown and 

reference groups. The influence of the original reference sample’s age composition on the 

estimated age of the skeleton(s) of interest (i.e., age mimicry) may represent a complicating 
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factor. This occurs when the age representation of the reference sample is deficient in part of the 

lifespan, so the distributions of particular age-informative traits are not the same in the skeletal 

sample and the living population. 

Acceptable age indicators fulfill four criteria: 1) morphological changes proceed unidirectionally 

with age; 2)features have a high correlation with chronological age; 3) changes occur roughly at 

the same age in all individuals (at least within a distinguishable subgroup); and 4) the 

characteristics are measured or classified with known intra- and interobserver error rates.

4.0 Best Practices

Whenever possible, standards for age assessment should be used that are most appropriate for the 

ancestry/population origin of the remains examined. Both sex-based and ancestry-based variation 

exists in dental and osteological development. When population-specific standards are not 

available, standards that are more inclusive (and with greater variance) should be used, and those 

standards should be documented in the report. 

Practitioners should have extensive knowledge of skeletal anatomy and experience with the 

various methods of age estimation. This includes both experience in the technique used during 

age estimation, as well as experience with osteological material. The analyst should be 

knowledgeable about the ranges of normal human variation in the teeth and skeleton. They 

should be attentive to pathological conditions that might have an effect on traits used for aging 

purposes, especially degenerative changes. 

The final age estimate is a matter of expert judgment by synthesizing all available information. 

Factors to be considered are: appropriateness of the reference data, skill in using one method 

over another, condition of the remains, applicability of statistical models, etc. 

4.1 Analyzing Immature Remains 

When and if teeth are present they should be assessed for their stage of development. Dental 

development has been demonstrated to reflect chronological age more closely than osteological 

development. Dental development appears to be under stronger genetic control, while 

osteological development is more influenced by environmental factors such as biomechanics, 

physiological stress and nutrition. 

Age estimates generated from the assessment of dental development are more reliable than those 

derived from the assessment of dental eruption. Significant variation exists among eruption times 

and the order of eruption in infants and children. 

Dental development is a more reliable means of estimating age than epiphyseal appearance and 

union. 
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Skeletal and dental maturation in females begins earlier than in males. The extent and nature of 

this difference varies among different populations. 

Epiphyseal union is more important than appearance for practical reasons. Small, incompletely 

mineralized lumps of bone are often poorly preserved, difficult to recognize in the field during 

recovery operations and hard to identify as specific bones. Often, with fresh cases, maceration of 

the body is not feasible and, therefore, radiographic assessment of the appearance of secondary 

ossification centers is important. 

The timing and sequence of epiphyseal union vary considerably among individuals. Several 

years can elapse between initial and final epiphyseal closure. For this reason, evaluation should 

consider the degree of closure. Epiphyses, depending on their location, provide different levels of 

accuracy and precision in estimating age at death. 

Gross inspection of bones can yield different information than radiographic assessment for the 

appearance of ossification centers and for epiphyseal union. 

While bone dimensions provide some indication of age, they are strongly affected by ancestry 

and life history, specifically growth retardation from poor health, including malnutrition. 

The following approaches are recommended for specific age categories: 

4.1.1 Fetal 

Since dental development is minimal in fetal remains, most estimates of age rely on bone 

formation, especially long bone lengths but also other bones such as the assessment of the 

development of the ilium and the petrous portion of the temporal. If accurate measurements can 

be taken, formulae exist to allow the calculation of body length and subsequently age. If 

developing teeth are present and can be correctly identified as to type, they can provide useful 

information as well. 

4.1.2 Neonatal, Infant, and Child 

If accurate assessment of dental development is possible, this method should be given more 

emphasis in age estimates. In the absence of dental information, assessments of skeletal 

maturation (including long bone lengths and maturation of other skeletal elements) can be used.

4.1.3 Adolescent 

In addition to skeletal measurements and dental evaluation, the extent of formation and union of 

epiphyses is important. Epiphyseal evaluation involves gross examination in skeletal remains and 

radiological assessment in fleshed material. 
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4.2 Analyzing Mature Remains 

Age estimation evaluation of adults can include examination of epiphyseal closure and dental 

development in younger adults, but methods generally involve assessment of degenerative 

skeletal changes and other features, including microscopic bone structure and dental features. 

Some methods for estimating age at death are more reliable for particular periods of adult life. 

Factors of the environment and life history of the individual can introduce non-age related 

variation in the expression of degenerative traits and thus represent a potential source of error. 

Most research suggests that for adults, consulting multiple age indicators provides more accurate 

results than using single indicators. 

5.0 Additional Considerations

In estimating age at death, it is important to be cognizant of the limitations of the various 

methods utilized. 

Some specific methods are more prone to produce biased age estimates than others for statistical 

reasons and the nature of the original reference samples. Proper documentation of the 

variation/error involved should be provided.

Younger individuals can in general be aged more accurately than older individuals. With 

increasing age, the variation produced by environmental factors and life history increases. \

The estimation of chronological age can involve important legal ramifications, especially for the 

living (e.g., unaccompanied and separated asylum seeking children, age of criminal 

responsibility).

6.0 Unacceptable Practices 

The following practices are considered unacceptable and should be avoided when estimating age:

Reporting overly precise age estimates without providing a proper documentation of the 

variation/error involved. 

Reporting age estimations without giving appropriate attention to sex and population 

factors.