Identification of an individual is an important task in forensic analysis. One of the methods applied in establishing the identity of an unknown individual is analyzing their biological characteristics. Biological characteristics are the natural features of a human individual present in her/his body which help identify, classify, differentiate, and individualize her/him.
Biological characteristics give a unique identity to an individual that helps forensic analysts to identify and individualize the victim and suspect/culprit. The main task in forensic medicine is establishing the identity of the deceased found at the crime scene.
The preliminary task of the forensic pathologist is to categorize the deceased on the basis of primary characteristics- race, age, and sex. Here in this article, we have discussed the various biological characteristics that can determine the age, sex, and race of an individual.
1. Biological Characterization Based on Age
Age is characteristic of an individual that classifies her/him in a particular group that limits the area of the investigation. The age of the deceased can be estimated by applying the principles of anthropology that use different body measurements (especially bones) that change with growing age.
1. Eruption of Teeth
During the early years of growth and development, the skeleton undergoes an orderly sequence of changes beginning with the formation and eruption of deciduous teeth and their replacement with permanent dentition by about the age of 12 years (excluding third molars).
Although the timing of this process varies somewhat by sex, race, and health factors, age at death can be estimated to be within 1 year in a normal sub-adult if the appropriate standards are used. Once the second molars have fully erupted, attention is focused on the skeleton.
2. Bones
The bony skeletal system is not complete at birth but instead begins with the formation and growth of centers of ossification. With a few exceptions, bones are endochondral in nature that is, first formed in cartilage which is gradually replaced by bone.
Until the beginning of adolescence, long bones, for example, consist of a diaphysis (shaft) and epiphyses at both ends. These are connected by cartilaginous metaphyses or growing regions that are replaced with bone when growth is complete.
Because growth at each bony joint is completed at different ages and in a set order, tracing the progression of epiphyseal union will allow age estimates to be within 1 year from about 13 through 18 years.
Thus, if a humerus has the distal (lower) epiphysis fused and the proximal (upper) epiphysis open, this indicates an adolescent between 13 and 18. Age is then pinpointed by determining which joints in the rest of the body have fused, where the union is beginning, and where all epiphyses remain completely open.
Note:- As with dentition, there can be variation by sex, population, and health status. Once growth is complete, age estimation becomes much more difficult because post-maturity age changes are subtle, irregular, and often highly variable from one individual to the next because remodeling rates and patterns are sensitive to many internal and external factors.
2. Biological Characterization Based on Sex
In the average living and still fleshed dead, sex is a discrete variable — one is clearly either male or female. Differences between the sexes are much less distinct in the skeleton where both morphologic and metric manifestations overlap to form a continuum.
There is, for example, no total size above which all are male and below which all are female. Again, if the adult skeleton is complete or at least has an intact pelvis, sex can usually be determined with 90-95% accuracy.
Primary sexual characteristics (e.g., external genitalia) are present in the soft tissue even before birth, but no such definitive marker has yet been observed in the skeleton. Although sex differences have been quantified in immature skeletons, they remain subtle until secondary sex characteristics begin developing during adolescence.
Attempts at sexing prepubescent bones have been made by using measurements of growth-based differences between males and females, but the results are far from definitive. In adults, the simplest and most accurate determination of sex can be made by morphological assessment of the pelvis.
As shown in the figure below, the pubic bones and sciatic notch are wider in females, resulting in an obtuse sub-pubic angle and more open pelvic inlet to facilitate childbirth. The male pelvis is narrower and constructed only for support and locomotion.
A thorough knowledge of cranial morphology can allow experts to approach 90 to 95% accuracy. However, the observer must be familiar with population-specific variants because sex-linked characteristics vary from one group to another.
In general, however, males tend to have rougher bones with larger crests and ridges, because these are often sites of muscle attachment. New research has led to the discovery that the mandible alone is nearly as sexually dimorphic as a complete pelvis.
In adult males, it has been observed that the posterior ramus has a distinct angulation or flexure at the level of the occlusal surface of the molars, while females retain the straight, juvenile configuration.
3. Biological Characterization Based on Race
Race may be defined as a rough classificatory mechanism for biological characteristics. There are three major race groups to which most people may be assigned: Caucasoid, Mongoloid, and Negroid.
However, there will always be equivocal cases because of admixture. Moreover, each group has a great deal of variation, and skin color is only one aspect of racial classification. Swedes, Italians, Egyptians, and Asian Indians look very different, but are all skeletally ―white even though some Indians may have dark brown skin.
Finally, even if a skeleton is clearly Caucasoid, there is no skeletal indicator of soft-tissue features such as eye color or hair form. In the skeleton, craniofacial morphology is the best indicator of racial phenotype.
A long, low, narrow skull exhibiting alveolar prognathism (forward protrusion of the jaws) and a wide, flat nose with smooth sills is characteristically black. Whites are typified by a high, round, or square skull, an orthognathic or straight face, and a long, narrow, protruding nose with sharp sills.
Conclusion
Establishing the identity of the deceased is an important task in the forensic analysis as it is the first step that leads to the investigation of a crime. Biological characteristics are the key features of a human individual which help to identify her/him.
Age, sex, and race are the primary features that determine the identity of a human individual. There are various methods to analyze these characteristics and determine the identity of an individual. However, not every method is 100 percent accurate.
Also Have a Look at:
- Types of Flies Used in Forensic Entomology For Investigation
- Polymerase Chain Reaction: The Boon in Genetics
- Applications of Proteins in Daily Life
- Forensic Odontology: Bite Marks as Evidence in Criminal Case
Frequently Asked Questions
1. Which is The Most Important Age Indicator of Humans?
Skeletons are considered one of the best age indicators. Teeth & Bones grow and mature with fair rates. From kids to Teenagers, teeth are the best indicators, and Pelvis and Skull sutures are the best age indicators for humans from teenage to old age.
2. Can DNA Determine Age?
Yes, DNA can be used to determine age. There are several methods that are used to estimate human age. One of the methods is based on the telomere length, mRNA, DNA rearrangement and aspartic amino acid that decreases with increasing age.
3. Can Hair Determine The Age of a Human?
The specific age of an individual cannot be determined by the microscopic examination of hair. However, the physical appearance of hair such as in infants and elders can give a general indication of age of an individual.
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