Age Assesment
Age of a person is not only how old a person is? But it is the sum a lot of factors together and their interaction and efficacy to assess the age of a person like your look, posture, voice quality, body built , body composition, anatomical structure and physiology of all the systems of the body. All these  factors together create a perception of the age of a person.
Methods of Age Determination
1.Chronological age:
Definition
a. Chronological age" refers to the actual amount of time a person has been alive. In other words, the number of days, months or years a person has been alive does not change, regardless of how healthy a lifestyle — even one filled with great exercise and nutrition habits — they are living.
b. Age of a person measured in years, months, and days from the date the person was born.
This can be easily estimated from the date of birth.

2. Biological age

Definition

Biological age means determination of age on the basis of  physiological efficiency of the body  i.e. How effectively all the systems of the body are  operating or functioning.

Biological age, also referred to as physiological age. 

Determination

Research suggests that telomeres and DNA methylation play big parts in the aging process. 

a. Telomere length: Telomeres are the nucleotides on the ends of chromosomes. They keep the ends of chromosomes from deteriorating and fusing with a nearby chromosome. Essentially, telomeres dictate how quickly cells age and die.

Scientists have discovered that the higher a person's chronological age, the shorter their telomeres.

One study found that people with shorter telomeres were more likely to have an early death or develop a disease or neurodegenerative disorder.²

Another study suggests that maintaining a healthy lifestyle can actually reverse aging by lengthening telomeres.

b. DNA methylation : Scientists are also using DNA methylation to determine biological age. Cells use DNA methylation to control gene expression. In other words, DNA methylation turns genes off. Although the exact purpose of methylation is unknown, it's vital to embryonic development, genomic imprinting, chromosome stability and more.

3. Secondary sexual development

A preliminary assessment of age can be subjectively performed based on the presence and prevalence of secondary sexual characteristics that become prominent throughout puberty (eg, breast development, the presence of pubic hair, and the laryngeal prominence in males). These characteristics develop as a result of sexual maturity. While these features highlight sexual dimorphism, their use as a tool for evaluating age within a living population is dubious.⁴⁶ Many factors can either inhibit or accelerate the development of secondary sexual characteristics, most notable of which is varied ethnicity, geographic location, and individual body shape/size.^47,48

4. Psychological development

UNHCR recommends multidisciplinary age assessments that consider both the physical appearance and age of the children, as well as their psychological maturity.⁵⁴

The Royal College of Physicians (RCP) emphasizes the importance of understanding the specific social history it is based on the following factors:

a. lifestyle,

b. familial role in country of origin,

c. and the type of education received.

These factors all contribute to psychological development, and by association the psychological age, of a child, and thus, as the RCP suggest, should be duly considered as a requirement in the derivation of a holistic estimation of living age.

5. Dental development

Tooth eruption was first used as an indicator of age in England, when the Factory Act of 1837 prohibited a child without a second permanent molar from working in factories.

Determination: Various Methods are utIlized for determinatIon of age fromdentition Age assessment methods may be classified as follows:

According to the state of development of the dentition:

A. Methods applied to the forming dentition

B. Methods for the adult fully formed dentition.

 According to the technique of investigation:

i. Clinical or visual

ii. Radiographic

iii. Histological

iv. Physical and chemical analysis.

Age Estimation Methods

Age estimation using the dentition may be grouped into three phases:

i. Aging in prenatal, neonatal and early postnatal period

ii. Age estimation in children and adolescents

iii. Age estimation in adults.

Determination of dental age is done by reference to the ever-growing human deciduous and permanent dentitions. The importance of age estimation includes an assessment of minor/major status in individuals without legal documents, Demirjian method, the widely used method with appropriate modifications shall be a reliable method.

6. Body Weight

The body weight of a normal healthy person may change with advancing age as BMR (Basal Metabolic Rate) decreases with increase of age.Reduction in BMR leads to weight gain with the same activity and diet although the activity decreases with advancing age this ultimately results in significant weight gain. One can avoid such changes by doing suitable changes in their diet and activity pattern.

7. Posture

Poor posture is an indicator of low fitness level and nutritional status.Poor posture is responsible for aged look in many cases like bend back. However, one can correct it with proper exercise , diet and self conscious attitude

8. Voice quality

Trembling voice is an indication of aging it occurs due to the reasons given  below:

1. Decrease in breath support: Itresults in weakened voice,this produces a strained quality of voice due to muscular tension dysphonia.

2. Laryngeal changes: Ossification of laryngeal cartilages and joints may cause bowing of vocal folds which is the most common cause of aging voice.Loss of vocal fold mass leads to decreased patients ability to bring the vocal folds together to make a weak breathy voice.

9. Body composition

The water content (indicator of muscle mass in most of the cases) of the body decreases and fat content goes up with advancing age if a person does not keep due allowances for aging and BMR changes taking place with in the body.

10. Skeletal maturation

Method used: Morphoscopic radiographic evaluation of skeletal development relative to full maturity

Parameters :

Hand and wrist bones: The hand and wrist bones develop at a known and predictable rate, and therefore, their development can be used to estimate age.

Medial clavicle: It has a particularly long developmental timeframe that spans adolescence through to adulthood, and is thus also frequently assessed.

11. Physical Fitness 

It is the most important criteria of body age assessment. It is the sum of biological age, physiological age and nutritional status.

Determination is done with the help of various tests corresponding to various components of fitness.

References

1. Defining Chronological and Biological Age, Sharon Basaraba   Medically reviewed by Isaac O. Opole, MD, PhD ,Healthy aging , very well health

https://www.verywellhealth.com/what-is-chronological-age-2223384 on January 10, 2020

2.RRFMS-75140-forensic-age-estimation-in-living-individuals--methodologica_101415.pdf

Research and Reports in Forensic Medical Science Dovepress

http://dx.doi.org/10.2147/RRFMS.S75140

Forensic age estimation in living individuals: methodological considerations in the context  of medico-legal practice, Daniel Franklin AmbikaFlavel Jacqueline Noble Lauren Swift ShalmiraKarkhanis School of Anatomy, Physiology and Human Biology, Centre for Forensic Anatomy and Biological Sciences, The University of western Australia, Crawley, wA, Australia