10 Age change and their relation to sex and ethnicity

Introduction:

Age is that period of being, length of time that a person or thing has existed. Age is continuous, irreversible, and always goes in high number as time lapsed. As time laps age increases. The term age and change both depended on each other, contextually one get stressed and another remains in supportive mode.

Examples:

1.      Moustache and beards appearing on a boy’s faces so, he is entering adulthood.

2.      Apparently, lady completes her 8th month of pregnancy so, in 9th month she is going to deliver a baby.

In example no.1 changes are stressed and age remains in support of it. Here, by observing the changes in a boy, his age is going to be estimated. 2nd example has age of pregnancy and predicting about change would be in 9th month.

Change will always follow the age and vice-versa, due to this reason we can use word age change for both. Age change is a natural and instinctive phenomenon. It is not possible to escape from age and age change. Age change, growth and development are go hand in hand. Growth and Development are determined and verified by age change itself.

Example:

1.      It is medically known that by the eighth week of embryo becomes child like appearance by the process of morphogenesis. It means by the eighth week though the rate of growth is slow, yet during this time the differentiation process in the mass to form various regions which later on give rise to different parts like head, leg, arm and so on starts.

2.      It is generally known that, it a baby is having low birth weight then it is directly associated with incomplete growth of a baby, that means baby born prior to 37 weeks of gestation which is also known as premature baby.

In first examples changes occur into the organism by its age raises (lapsed). There must be definite changes in definite age. Changes always follow the age. So here age determine the changes or growth and development. In second example if expected changes are not observed in an organism in a particular age, it could lead some problems. So here it verifies the growth and development of the organism.

A person himself and observer will experience age change in mainly three ways; those are as given below;

1.   Increase in Length

e.g: Stature, Head length, nose length, sitting height etc…

2.  Increase in surface Area

e.g: Circumferences of head, chest, waist, wrist, Mid upper arm circumference (MUAC) etc…

3.  Increase in Mass

e.g: Weight

Ø   These are measured by three different types

1. Linear :

It means having a form of a line or straight, which is usually evaluated in terms of increase in length (See above first example).

2. Areal :

It means of or pertaining an area. The areas or spaces inclosed. Which refers to growth of surface area (See above second example).

3. Ponderal:

Pertaining to weight or which means growth in weight or mass (See above third example).

Ø   Stages of Age Change

Life begins at conception when a new organism is created with the mother’s ovum fertilized by the father’s sperm. From that point till death an individual keeps on growing and changing. Such changes are not random but orderly and they generally follow a pattern. Development is the process by which organisms grow and change systematically over the entire life period i.e., from conception till death. Developmental changes are not only growth or additions to human organisms, they also involve decay. A child loses the milk teeth in the process of development and an old person may show decay in several areas of functioning. Development involves systematic changes in a direction in all aspects from size and proportion of the body to the ways of thinking, living and feeling. Thus, development is the total process of change in which all aspects of a person are interrelated and integrated. For example, a 13 year-old girl undergoes physical and biological changes in her body and such changes are related to her mental, social and emotional development also.

Age change, Growth and Development

We must also distinguish between growth, maturation and development. Development necessarily involves growth. But, growth is simply quantitative addition or change. As we become older, the body size, height, weight, proportion of parts of our body and the appearance of different limbs and parts change in measurable ways. Development involves growth and other qualitative changes. Developmental changes also include changes due to maturation. Maturation is the change which is biological in nature and which is due to our genetic endowment. The genes that we inherit contain blue prints for changes in an orderly and predetermined sequence following a sort of biological clock. Changes like falling of milk teeth, graying of hair, a child’s onset of walking, bodily changes during adolescence and even change as in the way we think and understand are affected by our maturational readiness. Our biological system follows a predetermined time table preparing us for developmental changes. Maturational changes in our body or behaviour are primarily due to the aging process rather than learning or other factors such as illness or injury. Maturation and our experience in the environment jointly bring about changes in our development.

Human development from conception to death is generally viewed as occurring through eight stages. The major developments during each of these stages are described below:

1.  Pre-natal Stage

The developments from conception till birth of a baby constitute the prenatal stage. The approximate period of prenatal development is taken to be 9 calendar months or 10 lunar months (i.e., 280 days), although babies are not born exactly after 280 days of conception. Biologically it takes about 266 days from conception for a fetus to become ready for the birth process. Actual birth of normal full term baby may take place any time after that.

Prenatal stage is further divided into three phases. The first phase – the germinal period – is the period from conception until implantation. Conception occurs when a sperm penetrates the wall of a ripened ovum forming a zygote. In about 8-14 days, the zygote gets firmly attached to the wall of the mother’s uterus. This is called implantation which brings the germinal period to end.

The second phase of prenatal development is the period of the embryo which lasts from the beginning of the third week to the end of the eighth week. During this time all major organs are formed and the heart begins to beat.

The third phase is the period of the fetus. It lasts from the third prenatal month until the ba by is born. The major organ systems begin to function and the growth of the organism is quite rapid.

2.  Post natal Stage

Growth starts from the time of birth up-to adulthood or the time of maturity.

Infancy

The period from birth to two years constitutes the infancy stage of life. Maternal influence of birth weight and birth length is more important than the genotypes of the child. Immediately after birth the rate of growth increases. In case of weight the peak velocity is reached at two months after birth. By building up the cytoplasm in the cells of the muscles and also incorporating salt in them and by the formation of proteins the growth at infancy continues, in this process decrease of water concentration and disappearance of the intercellular contents are observed. The cells become larger in size. General chubbiness and head and trunk of relatively large dimensions are characteristic features of a child during infancy. The cervical and lumbar curvatures of the spinal column appear as the baby begins to straighten the head and tries to sit up and stand.

Childhood

On the basis of distance and velocity curves the pattern of growth during childhood can be obtained. That pattern may be regarded as the standard for a particular population and the growth pattern of the children of that population can be predicted accordingly. Both heredity and environment play their respective role in physical growth. Therefore the heredity growth potential of a child may be influence by the various environmental factors which include nutrition, state of health, socio-economic condition of parents, psychological well being and the like. There are population variations in the pattern of growth.

The early childhood is the period of eruption of deciduous or milk teeth. All milk teeth are erupted during this period and permanent dentition also shows its beginning. During this period the growth is relatively more in width than in height. In middle childhood permanent teeth, though not all, erupt. In this period size of head increases slightly. Linear growth of the body takes place rapidly and the waist line becomes definable. In late childhood phase of growth stage starts from the pre-pubertal period and continues up to the time of puberty. It is actually occurs around 14 years. Sexual morphological differentiation normally begins during this phase. The rate of growth decreases during childhood. It becomes negligible towards the end of the late childhood phase. But a notable increase in growth velocity, known as the adolescent growth spurt, is observed which however is associated with the onset of sexual maturation.

Adolescence

The adolescence period extends from the time of puberty up to around 20 years. The acceleration of growth at adolescent causes many anatomical changes almost in all parts of the body. Sexual maturation takes place during this period.

According to some this period may be divided into pre-puberal and puberal phases. The pre puberal phase lasts for about two years. During this time the increase of weight is retarded. Height increases by the lengthening of the legs. The thorax becomes narrow, trunk becomes short, legs and arms become long.

During puberal period sexual organs are matured. The body proportions are changed. Secondary sexual characters appear. In girls the first menstruation marks the beginning of ovarian activity. But in boys it is difficult to ascertain precisely the time of maturation of the testes. The most obvious secondary sexual characters in girls are the development of breasts, appearance of axiliary and pubic hairs. In boys also pubic hair and beard and moustaches show appearance

Adulthood or Maturity

The cessation of growth of height is regarded as sign of maturity. Height ceases to grow when the long bones, example: tibia, fibula etc. lose their capacity to increase in length. Usually males attain the adult height at about 21 years of age and females at 18 years of age.

Another important sign of adulthood is reproductive maturity. During this period reproductive maturity begins but not completed. On average adult males are heavier an taller than adult females.

3.  Senescence

After the prime period of adulthood senescence starts. The aging pattern shows great individual variation. The aging time also differs from person to person and society to society, because environment plays an important role. During this period many molecular and cellular changes occur. Organismic changes are also there. These changes are measureable and can be described, but these do not exhibit any specific pattern or well defined sequence. Because of aging the tissues do not renew and as a result cells show senile involution. The memory declines. Aged persons need more time to learn and to react. The speed of conduction in motor nerves shows a decline. Systolic blood pressure increases. Peripheral resistance and circulation time in the cardiovascular system show an increase. The range of accommodation of the eyes lens declines. There is reduction of density of long bones and vertebrae and therefore height and sitting height show decreases. Arm span circumference of forearm and that of calf diminishes. Vital capacity and muscle tone declines.

Ø   Ethnic differences

Racial groups show differences among them in respect of certain descriptive morphological traits. Krogman (1955) listed some characteristics of the skulls of three major races, namely, Caucasoid, Negroid and Mangoloid. He has given description of skull of these divisions. Comparing the descriptive morphological and metric characteristic of a given skull with those of the groups, the skull may be assigned to one group.

Though determination of age on the basis of skeletal remains is not an easy task, because of great deal of individual variability at different times have made attempt to ascertain the age of an individual at death taking into account certain characteristics. In case of children it is comparatively easy to suggest the judging the extent of ossification of bones and eruption of teeth, sometimes it is possible to suggest the approximate age in case of adults as well, as with age many changes occur in the skeleton including the skull.

Example: with the advancement of age obiliteration of the sutures of vault of the skull takes place. On the inner surface of the skull it may starts between 40 and 50. The lower part of the coronol suture is the first to exhibit obliteration, next comes the posterior part of the sagittal sutures, to be followed by the lamboid sutures. In general the skull becomes lighter and thinner in old age. The loss of teeth is another notable event of old age, as a result of which the size of the mandible and that of the maxilla shrink.

As regard eruption of tooth, very generally it could be said that the first molar tooth of the permanent set erupts by 7 years of age and by 14 the second one appears.

For determination of sex mostly two parts of the skeleton are thoroughly examined, because in these two sex differences are more pronounced. The parts are, the skull and the pelvis. The female pelvis needs certain special features to make necessary provisions for parturition and that make female pelvis distinguishable for male pelvis. The sex differences, however are not very distinct in young age. In the adults the differences are more marked. The same is true in case of sex differences in skull. It should be kept in mind that in some skulls and also in pelvis the distinguishing features are very well marked making it easy to determine the sex.

Sex differences are observed in other parts of the skeleton. The differences are listed below-

• Thorax is slightly differs from the female thorax.
• Cervical and lumbar vertebrae also exhibit differences.
• Some other bones like humerus, radius, ulna clavicle, scapula, sternum, femur and tibia helps in ascertaining sex.

Teeth show a wide range  of morphological  variations,  which help  in  identification of an individual. There may be an extra tooth (supernumerary tooth), an extra cusp on a tooth, an extra root in tooth, absence of a tooth, missing root etc. shape is another aspect. It may be shovel shaped or peg shaped. Thus there are several aspects of dental characters which may help in identification.

In the context of person identification we can recollect the qualities of dermatoglyphic traits and their use in personal identification. Illiterate persons put their left thumb impression instead of signature and this is accepted by all, because the ridges of finger are unchangeable, no two persons are exactly alike in dermatoglyphic traits, etc.

The Negroes are being shorter and having coarse feature in face and body. Among them nose is very broad, its root is low and the bridge flat, cheek bones are prominent, face is marked prognathous, chin is retreating and lips are markedly everted. Ears small with little or no lobe. The head predominantly long with protruding occiput and rounded head and brow ridges are small.

Mangoloid are having some ethnic differences, scanty body and facial hair, broad flat face with prominent cheek bones, oblique eye with narrow slit like opening and internal epicanthic fold or total mongoloid fold.

Caucasoids include numerous ethnic groups with diverse racial elements. The head form, it ranges from dolicocephalic to brachycephalic, high nasal bridge, prognathism is usually absent, cheek bones are generally not prominent, forehead is comparatively high.

Ø   Age Estimation Methods

Age estimation, as terms themselves suggests that it is a calculation of a particular thing or subject’s age. It can be done through many ways or methods some of them are given below;

Physical examination

Physical examination in cases of age determination should include measurements such as body height and weight, body type and body mass index, as well as any visible signs of sexual maturity and the results of a general physical examination, and should describe any signs suggestive of a pathological condition which may interfere with the maturation rate of the child. There seems to be general agreement among authors that the interpretation of results obtained from anthropometric variables is an imprecise factor for the prediction of chronological age. Some studies have shown that individuals of greater height and weight and those with an athletic body type and an above-average BMI are among those who, in a specific population, may exhibit a more advanced bone age in relation to actual chronological age. Signs of sexual maturation are examined by evaluating the stage of development of the penis and scrotum, pubic hair growth, axillary hair growth, facial hair growth, and laryngeal prominence in male subjects; and breast development, axillary hair growth, and shape of the hip in female subjects. The most widely used method for the study of secondary sexual characteristics is the staging described by Tanner. The method was devised to estimate the stage of development or physiological age for medical, educational or sports purposes, and to identify delayed or advanced sexual maturation when the chronological age of the subject is known. The method uses a five-stage scale to evaluate the status of pubic hair growth and breast development in girls, and pubic hair growth and development of the penis, scrotum and testes in boys.

Auxiliary hair growth, facial hair growth and laryngeal prominence development may also be assessed using the four-stage classification proposed by Nezy et al. Of the forensic methods recommended for age determination, assessing age on the basis of physical traits is the least precise. Evaluating sexual maturity has the greatest margin of error and should be used for age determination only in conjunction with an evaluation of skeletal maturity and tooth development. Multiple pathological conditions and non-pathological, idiosyncratic conditions cause a large range of variation in the onset of external changes associated with sexual maturation in different subjects. Therefore, age determination cannot be made on the basis of these examination data alone. Moreover, irrespective of the difficulty in interpreting the results due to inter-observer and intra-observer differences, there are few series analyzing the progression of these parameters with chronological age in different populations, and the few available are mainly focused on developed countries. However, the physical examination is extremely useful for evaluating the potential impact of pathological factors on the maturation status estimated using other methods. The great discrepancy between height, weight and external signs of maturation and the bone and dental age estimated using radiographic methods should guide the examiner on the potential interference of pathological conditions and to a weighted estimation of age. Most diseases delay development and are thus conducive to underestimation of age. Such underestimation of age would not disadvantage the person concerned in the judicial framework. By contrast, overestimating age due to a disease that accelerates development should be avoided at all costs. Certain diseases which occur very rarely, in particular endocrine disorders, may affect not only the attainment of height and sexual development, but also skeletal development. Endocrine diseases that may accelerate skeletal development  include  precocious  puberty,  adrenogenital  syndrome,  and  hyperthyroidism. Similarly, a general physical examination may show symptoms such as exophthalmoses, virilisation of girls, acromegaly and gigantism, which are indicative of pathological disorders and must also, redirect the estimation of age. Another indication of a possible endocrine disorder is a discrepancy between skeletal age and dental age, as dental development normally remains unaffected by endocrine disorders.

Various methods are utilized for determination of age from dentition. These may be described in four categories namely, clinical, radiographic, histological, physical and chemical analysis.

i)    Clinical or visual method: Visual observation of the stage of eruption of the teeth and evidence of changes due to function such as attrition can give an approximate estimate of age.

ii)   Radiographic method: Radiography can provide the gross stage of dental development of the dentition.

iii)     Histological method: Histological methods require the preparation of the tissues for detailed microscopic examination, which can determine more accurately the stage of development of the dentition. This technique is more appropriate for post-mortem situations. It is also significant in estimation of age of early development of dentition.

iv)   Physical and chemical analysis: The physical and chemical analysis of dental hard tissues to determine alterations in ion levels with age have been proposed. While these techniques, as yet, are not of great value to the forensic odontologists, future developments might provide an adjunctive means of collecting evidence of value in the dental context.

Ø   Summary

Change is the law of nature and age change is instinctive phenomenon. Each and every object or organism in the nature has its own life span and duty. Every object or organism get specialized characteristics as its age increased and its stops at a point after that the level of performance the gradually come down. Infancy, childhood, adolescence, adulthood and senescence or old age is the best example for age change. Age change will occur mainly in three ways and these are measured in three methods- increase in length measured by linear method, increase in surface area measured by areal method and increase in mass which is measured by Ponderal method.

Age change itself creates major differences between sex, though in early stage difference are less. But in later stage all gradual changes are observed much, like boy gets moustache and beards, voice gets hard auxiliary and pubic hairs appeared etc. whereas a girl experiences menstrual cycle, smoother voice , auxiliary and pubic hairs appeared and breast development etc. The age change stages are remains same all ethnicity but in the level they acted upon them is differs from one ethnic group to another, for example Cacusoid, Mangoloid and Negroid.

Many methods are used to identify the sex and also estimate the age some of them are as follows- Clinical or Visual Method, Radiographic Method, Histological Method, Physical and Chemical Analysis and Osteological Method.