Forensic identification from skeletal remains incorporates various parameters that conclude to identification in terms of gender, age, stature etc.
Estimating the age from bone samples recovered from crime scene is a tedious task to perform. The age of a person from his skeletal remains cannot be determined absolutely, though the forensic anthropologists can estimate with certainity to which age group the bone samples belong e.g. By analysis of skull sutures, it can be said that the skull is that of an adult between 20-25 years of age, however, saying that the skull is that of a person with age of 25 years is rarely possible and if said, it has to be corroborated by various other evidences supporting the fact.
Determining the age from skeletal remains becomes important from forensic perspective as it provides the investigating agencies, the data that is important to establish the identity of the person by delimiting the area of investigation. There are numerous methods for age estimation from human bones that forensic anthropologists have been using from the past including closure of fontanels and sutures found in skull, analysis of dentition, epiphyseal fusion in long bones etc. Let us study these features in detail:
Fontanels1
Fontanels are cartilagenous soft-tissues found in between the cranial bones of infant skull. They hold cranial bones in position in an infant as the cranial bones are not completely ossified in the skull of a newborn. Fontanels are of huge importance as they provide the infant skull with a great degree of flexibility that helps the infant descend through the pelvic outlet of mother. Another significance of fontanels is that it helps the skull accommodate space for growing brain. As the infant grows, fontanels are replaced by fixed joints called sutures that ossify cranial bones in position. Generally, all fontanels are closed by 5 years of postnatal life but may remain open in case of some congenital abnormalities. Human infant skull generally has 6 fontanels:
- Anterior fontanel (largest, present in bregmatic region)
- Posterior fontanel (present in the occipital region, also known as lambdoidal fontanel)
- Mastoid fontanel (two, present on either side of skull above the region of mastoid process)
- Sphenoidal fontanel (two, present on either side of skull above sphenoid bone)
The closure time and sequence of these fontanels are listed in the table below:
Fontanel | Closure time (post birth) |
Posterior fontanel | 2-3 months |
Sphenoidal fontanel | Around 6 months |
Mastoid fontanel | 6-18 months |
Anterior fontanel | 1-3 years |
Table 1 showing closure time of various fontanels*
Picture 1 showing fontanels of skull, lateral view (left) and top view (right).
Picture Reference- Source
Sutures2
When it comes to age estimation from skeletal remains, skull is the most common structure available and used due to its structural robustness as it remains unaffected by environmental changes, mass disasters, animal interference, fire burns etc. Age estimation from skull is usually done by examination of sutures. Sutures are the joints which hold the cranial bones in position. As the infant ages through his life, sutures replace fontanels. In a skull, sutures can be seen as zig-zag lines between various cranial bones, which are initially unfused but fuse later, gradually as the age advances.
Sutures are the most common parameters used for age estimation but also the most uncertain one. Many researches have suggested that though sutures are most frequently used for age estimation they offer a wide degree of variability in closure time. This variability may be natural depending upon the environment, sex, race, nutrition etc. of a person or may be due to the presence of congenital abnormalities. It has been found that ectocranial sutures closure is variable naturally but endocranial suture closure is stable, hence, while estimating age from cranial sutures the endocranial sutures should be preferably examined. Overall, it can be said that age estimation from sutures is the easiest and simplest to carry out but involves a huge amount of risk. Let us look at various sutures found in human skull:
- Metopic sutures: articulation of two frontal bones in the forehead region
- Coronal suture: articulating frontal and parietal bones
- Sagittal suture: articulating both parietal bones together
- Lambdoid suture: articulating parietal bones with occipital bone
- Basilar suture: between occipital and sphenoid bone
- Squamosal suture: between parietal and temporal bone
Other sutures used to estimate age:
- Occipito-mastoid suture: between occipital bone and mastoid portion of temporal bone
- Parieto-mastoid suture: between parietal bone and mastoid portion of temporal bone
- Spheno-temporal suture: between temporal and sphenoid bone
- Spheno-parietal suture: between parietal and sphenoid bone
Pictures 2 showing sutures of skull in lateral view.
Picture Reference : Source
Picture 3 showing sutures of skull in posterior view.
Picture Reference: Source
The ectocranial and endocranial closure time of these sutures are given in the tables below:
Suture | Endocranial fusion begins by | Endocranial fusion completed by |
Sagittal suture | 26 years | Complete fusion by 61-65 years of age |
Coronal suture | 26 years | Complete fusion by 56-60 years of age |
Lambdoid suture | 25-30 years | Complete fusion by 60-70 years |
Squamosal suture | 55-60 years | Complete fusion by 70 years of age |
Table 2 endocranial closure time of major sutures of skull*
Suture | Fusion begins by | Fusion completed by |
Metopic suture | — | 2 years |
Basilar suture | 13 years | 22 years |
Sagittal suture | 30-35 years | 50 years, may be extended up to 60 years |
Coronal suture | 35-40 years | 50 years, may be extended up to 69 years |
Lambdoid suture | 45-50 years | 55-60 years, may be extended up to 67 years |
Occipito-mastoid suture | 60-65 years | 80 years |
Parieto-mastoid suture | 60-65 years | 80-82 years |
Spheno-temporal suture | 50-55 years | 70 years |
Spheno-parietal suture | 60-65 years | 70 years, may be up to 80-85 years, last suture to close |
Table 3 showing closure of various skull sutures*
*the closure time of sagittal, coronal and lambdoid sutures in table 3 are ectocranial, while that of other sutures mentioned in the same table are not specified.
*the closure time of various sutures and fontanels mentioned in the tables above are based on researches conducted, these values are subject to vary.
General interpretation: A general interpretation made by analyzing the major sutures like sagittal, coronal and lambdoid suture is that if all the three sutures are not fused, the age of skull is said to be under 30 years. While, if these sutures are completely fused the age of the skull is said to be above 40 years.
Epiphyseal fusion, ossification of bones and fusion of joints3
The process of bone formation has been explained previously. In a newborn child bones are not in fully developed, they develop as the infant ages through his life. If the radiograph of a newborn child is examined carefully, it can be seen that bones do not occur in their mature shape. Major portions of the bones like condyles, facets, processes, apophyses etc. are not fully developed and if developed, are not in fused state with the rest of the bone. Various joints of the body like shoulder joint, elbow joint, wrist joint, hip joint, knee joint etc. are not fused at the beginning. Gradually as the infant matures, bones are completely ossified at their epiphyseal and diaphyseal or other ends and joints are also articulated. These processes take place during a particular interval of the individual’s life and hence can be used to ‘estimate’ the age of a person from skeletal remains in the field of forensics. Examination of bones or skeleton as a whole can give an estimate idea of the age, however, the information provided is delimited by the facts that the development and fusion of bones and joints are a subject to vary with environment, population, race, heredity, nutrition, presence of congenital abnormalities or bone diseases. Let us study the ossification time of various bones and joints in the tables below:
- Scapula
Name of epiphysis | Fusion |
Coracoid epiphysis | Females-15-18 years Males-17-18 years |
Glenoid epiphysis | Females-17-20 yearsMales-19-20 years |
Inferior angle | Females-21-22 yearsMales-19-21 years |
Acromial epiphysis | Females-18-21 yearsMales-19-21 years |
Table 4 showing estimate epiphyseal fusion ages of scapula.
- Clavicle
Name of epiphysis | Fusion |
Secondary epiphysis at the medial end of clavicle | Fusion with medial end-18-25 yearsFusion of medial clavicle with rest of the bone-25-31 years It is the last epiphysis to fuse |
Table 5 showing time of ossification of clavicle in humans.
- Humerus
Name of epiphysis/portion of bone | Appearance | Fusion |
Head of humerus | 1st year | — |
Greater tubercle | 2nd year | — |
Lesser tubercle | 5th year | — |
Fusion of above three to form conjoint epiphysis | — | By 6 years |
Union of conjoint epiphysis with shaft | — | Females-13-17 years Males-16-20 years |
Medial epicondyle | — | Females-17-20 years Males-19-20 years |
Distal humerus | — | Females-15-18 years Males-17-18 years |
Table 6 showing estimate epiphyseal fusion time of humerus.
- Radius
Name of epiphysis | Fusion |
Proximal radius | Females-17-20 yearsMales-17-20 years |
Distal radius | Females-20-23 yearsMales-21-23 years |
Table 7 showing estimate epiphyseal fusion time of radius.
- Ulna
Name of epiphysis | Fusion |
Proximal ulna | Females-15-17 yearsMales-16-17 years |
Distal ulna | Females-20-22 yearsMales-20-21 years |
Table 8 showing estimate epiphyseal fusion time of ulna.
- Femur
Name of epiphysis | Fusion |
Proximal end | 15.5-19.5 years |
Distal end | 14.5-19.5 years |
Table 9 showing estimate time of epiphyseal fusion in femur.
- Tibia
Name of epiphysis | Fusion |
Proximal end | 14-17 years |
Distal end | 14.5-19.5 years |
Table 10 showing estimate time of epiphyseal fusion in tibia.
- Fusion of joints
Name of joint | Fusion |
Shoulder joint | Females-17-20 yearsMales-18-20 years |
Elbow joint | Females-17-18 yearsMales-18-19 years |
Wrist joint | Males-19-20 years |
Knee joint | Males-17-20 years |
Pelvis (fusion of iliac crest and ischial tuberosity with pelvis) | Males-20-22 years |
Table 11 showing estimate time of fusion of major joints in humans.
- Vertebrae
Name of vertebrae | Fusion |
Sacral (5 vertebrae) | Begins by 16-20 years, completely fused by 30 years |
Coccygeal (4 vertebrae) | Delayed fusion than that of sacral vertebrae, occurs between 20-30 years |
Table 12 showing estimate time of fusion of sacral and coccygeal vertebrae.
- Sternum
Name of portion | Fusion |
Sternebrae S1 and S2 | 21-30 years of age |
Sternebrae S2 and S3 | 16-25 years of age |
Sternebrae S3 and S4 | Completed by 16-20 years |
Manubrium and body of sternum | Begins after 40s and completed during 50-60 years of age |
Xiphoid process and body of sternum | Begins after 30s and completed during 40-60 years of age |
Table 13 showing estimate time of fusion of various portions of sternum.
Estimation of Age from Dental examination4
- Eruption of deciduous and permanent teeth
Deciduous or temporary dentition comprise the teeth present in an infant or toddler. These are also known as primary teeth. Deciduous teeth erupt during early postnatal life and shed after a particular time during the life. These teeth are then replaced by permanent teeth which comprise the dentition of a mature individual and do not shed or if shed, are not replaced. The time of eruption and shedding of these two sets of teeth can be used to estimate the age of an individual by examining his dentition as this transition occurs during particular time intervals of the life. However, the age estimated by this method may not be accurate as the time of eruption and shedding of teeth in humans varies a lot with race, gender, heredity or dental abnormalities. Let us look at the eruption and shedding times of the two sets of dentition in the tables below.
1.1 Deciduous teeth
Upper jaw | Eruption | Shedding |
Central incisor | 8-11 months | 6-7 years |
Lateral incisor | 9-13 months | 7-8 years |
Canine | 17-22 months | 10-12 years |
First molar | 14-16 months | 9-11 years |
Second molar | 21-32 months | 10-12 years |
Lower jaw | Eruption | Shedding |
Central incisor | 6-10 months | 6-7 years |
Lateral incisor | 8-13 months | 7-8 years |
Canine | 17-22 months | 9-12 years |
First molar | 13-16 months | 9-11 years |
Second molar | 20-32 months | 10-12 years |
Table 14 showing estimate time of eruption and shedding of deciduous teeth in humans.
Picture 4 showing primary dentition in humans.
Picture Reference : Source
1.2 Permanent teeth
Teeth | Eruption (Upper jaw) | Eruption (Lower jaw) |
Central incisor | 6-9 years | 6-9 years |
Lateral incisor | 8-10 years | 7-9 years |
Canine | 10-12 years | 10-12 years |
First premolar | 9.5-11 years | 9-11 years |
Second premolar | 10-12 years | 10-12 years |
First molar | 5-7 years | 6-8 years |
Second molar | 12-14 years | 12-14 years |
Third molar | 17-24 years | 17-24 years |
Table 15 showing estimate time of eruption of permanent teeth in humans.
Picture 5 showing permanent dentition in humans.
Picture Reference: Source
1.3 Gustafson’s method
Till now we have studied age estimation from teeth in terms of dentition, but it is not necessary that the entire skull is found at the crime scene. With time, criminal minds have advanced and have known the fact that how science has developed various methods of identification of corpses even from minute details. In the present time, criminals tend to destroy every single detail that could lead to the identification of corpses and ultimately their conviction. So, methods like burning the corpses or dismemberment of various body parts are the methods most likely adopted by criminals that challenge the scientific brains. In such cases, forensic scientists need to work at their best. Even a single tooth found at the scene of crime can be used to estimate the age, yes, a single tooth, how? Let us study this in detail:
Gustafson devised a method of age estimation on the basis of regressive changes that occur due to wear and tear of teeth. He developed a regression equation on the basis of his research which can be used to estimate the age from teeth. In this method, the morphological factors of a tooth that are taken into account can be divided into 6 categories as under and each factor has been allotted a score ranging from 0-3 based on observed condition of the tooth as mentioned below:
- Amount of attrition on incisal or occlusal surface (A): It is scored as under:
Score | Condition |
A0 | No attrition |
A1 | Attrition limited to enamel level |
A2 | Attrition limited to dentin level |
A3 | Attrition up to pulp cavity |
- Secondary dentine deposition (S): It is scored as under:
Score | Condition |
S0 | No secondary dentin formation |
S1 | Secondary dentin up to upper part of pulp cavity |
S2 | Secondary dentin up to 2/3rd part of pulp cavity |
S3 | Diffuse calcification of entire pulp cavity |
- Periodontal diseases (P): It is scored as under:
Score | Condition |
P0 | No obvious periodontal disease |
P1 | Beginning of periodontal disease but no bone loss |
P2 | Periodontal disease more than 1/3rd of the root |
P3 | Periodontal disease more than 2/3rd of the root |
- Cementum apposition (C): It is scored as under:
Score | Condition |
C0 | Normal cementum |
C1 | Thickness of cementum more normal |
C2 | Abnormal thickness of cementum near the apex of the root |
C3 | Generalized abnormal thickness of the cementum throughout the apex of the root |
- Root resorption at apex (R): It is scored as under:
Score | Condition |
R0 | No resorption |
R1 | Spotted resorption |
R2 | Resorption limited to cementum |
R3 | Extensive resorption of the cementum and dentin both |
- Translucency of root (T): It is scored as under:
Score | Condition |
T0 | No translucency |
T1 | Beginning of translucency |
T2 | Translucency more than 1/3rd of apical root |
T3 | Translucency more than 2/3rd of the apical root |
Once all the six observable factors of a tooth are allotted a particular score, all the scores are summed together to get a new value. For example- X = (A1+S2+P0+C3+R2+T3).
This new value i.e. ‘X’ is put in the regression formula developed by Gustafson and the age of person can be determined. The regression formula for the same is:
AGE = 11.43 + 4.56 (X)
The average error in the age estimated by this method is ±3.63.
*All the data of estimate time of epiphyseal fusion, fusion of joints, eruption and shedding of teeth etc. are obtained by comparative analysis of researches conducted across various parts of the world. The data provided is not universal and is a subject to vary.
References
1-http://carta.anthropogeny.org/moca/topics/age-fontanelles-cranial sutures-closure.
2-i) S.V Khandare et. al, Age estimation from cranial sutures-a Postmortem study, International J. of Healthcare and Biomedical Research, Vol. 03, Issue 03, 2015, ISSN: 2319-7072, www.ijhbr.com.
ii) Manivasagam M., Age Estimation From Fusion Of Ectocranial (Coronal, Sagittal, Lambdoid, Temporal) Sutures In Humans-A Study In Bodies During Autopsy To Prove/Disprove Ages Of Sutural Closure Used In Routine Practice.www.repository-tnmgrmu.ac.in
iii) Cardoso, Hugo, (2009), Does the timing of basilar suture closure provide reliable information for age estimation of unidentified human skeletal remains in a forensic context?
iv) Sabita Singh et. al, Morphological Variation and Occurrence of Persistent Metopic Suture in Indian Population, National Journal of Basic Medical Sciences, Vol. 8, Iss. 2. 2017, DOI: 10.7324/NJBMS.2018.8202
3.1,4,5. H.F.V Cardoso, Epiphyseal union at the shoulder girdle and upper limb, American Journal of Physical Anthropology, 137:97-105 (2008), Wiley-Liss, Inc. DOI: 10.1002/ajpa.20850.
3.2. Jasuja et. al, Estimation of age from ossification of clavicle, J. Indian Acad. Forensic Medicine, 31 (3).
3.3 D.S. Saravanan, Determination of age from radiological examination of shoulder joint, repository-tnmgrmu.ac.in.
3.6,7. http://jenjdanna.com/blog/2011/12/13/forensics-101-epiphyseal-fusion.html
3.8. William B.C Sangma et. al, A Roentgenographic study for Age Determination in Boys and Girls of North-Eastern Region of India, J. Indian Acad. of Forensic Medicine, 2006: 28 (2), ISSN: 0971-0973.
3.9. Gerard Tortora and Bryan Derrickson, Principles of Anatomy and Physiology, Volume 1, International Student Version
3.10. Tayal Ishwer, Rai G., Gargi J. and Chanana A. (2013). Medico-legal importance of sternum in age estimation-an autopsy study. Journal of Punjab Academy of Forensic Medicine and Toxicology, 13 (2), 80-85.
4.1.1 Singh Kuldeep, Gorea Rakesh, Bharti Vipin (2004), Age estimation from eruption of temporary teeth, J. Indian Acad. Forensic Med., 26 (3), ISSN: 0971-0973.
4.1.2 Singh Kuldeep, Gorea R.K., Bharti Vipin (2005), Age estimation from eruption of permanent teeth, J. Indian Acad. Forensic Med., 27 (4), ISSN: 0971-0973.
4.1.3 Bajpai M., Pardhe N., Kumar M., Agrawal S. (2015), A Comparative Evaluation of Gustafson’s formula and New formula for age estimation in India-A Forensic Study, Prague Medical Report / Vol. 116 (2015) No. 3, p. 203-209. DOI: 10.14712/23362936.2015.59
4.1.3 Singh A., Gorea R.K., Singla U., Age Estimation from Physiological Changes of Teeth, J. Indian Acad. Forensic Med., 2004; 26 (3). ISSN: 0971-0973.
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