Biological age - Anatomy and age physiology

Biological age

Each person has his own pace of development - the speed of "unfolding" genetic program in specific environmental conditions. The difference between the degree of maturity of an organism and its calendar age in some cases can be significant. Therefore, an important indicator of development in anthropology is the correspondence of the passport (calendar) and biological age.

The period of time passed in absolute terms (ie in years, months, days, etc.) from the moment of the birth of a person to this particular moment is called chronological, or passport, age; the age of a person, estimated by the degree of development (or maturity) of individual characteristics and systems of characteristics, - biological age.

Children having the same calendar age can be at different stages of maturation, i.e. have a different biological age. It is reflected in the terms of eruption of the milk teeth and their change to permanent teeth, the formation of ossification nuclei in the cartilaginous tissue of the skeleton, the timing of puberty, in some functional and biochemical indicators, and the peculiarities of psychophysical development. By the ratio of anthropometric data (weight and height indices), the level of biological maturity and mental development, a harmonious and disharmonious type of development is distinguished. The essential difference between the biological age and calendar leads, as a rule, to the violation of the child's adaptation to the age requirements presented to him by the social environment.

The main criteria of biological age are grouped according to the characteristic systems:

indicators of morphological maturity - general somatic development; tooth maturity; skeletal age; development of the reproductive system (puberty);

physiological and biochemical indicators - primarily indicators of basic, carbohydrate and lipid metabolism; secretion of enzymes and hormones; features of the cardiovascular system, neurodynamic and neurophysiological characteristics;

indicators of neuro-psychological development.

Determining the biological age for odontological (dental) traits is based on counting the number of erupting teeth and the sequence of their eruption. These data are compared with the developed standards, resulting in an interval estimate of the age of the individual - dental age.

The tooth age is determined to within a year, sometimes even more accurately. This is a great advantage of the method in comparison with all other criteria. However, the tooth age is the most informative only during periods of dairy eruption (on average from 6 months to 2 years) and permanent teeth (from 5-6 to 13-14 years, without taking into account third molars - wisdom teeth), it is not indicative after eruption of all permanent teeth. Consequently, this method is unsuitable for determining the biological age in adolescence and adulthood. Indicators of tooth age are presented in Table. 2.7.

Table 2.7

Normal periods for the eruption of dairy and permanent teeth

Teeth (name and designation)

Age limits

Milk Shift

Permanent Change


Internal (i 1 and I1)

6-8 months

6-8 years

Outdoor (i2 and I2)

7-12 months

7-9 years


Canines (s or C)

16-20 months

10-14 years

Premolars (or premolars)

The first (P1)

12-16 months

9-12 years

The second (P2)

20-30 months

11 - 13 years

Molars (or aboriginal)

The first (ml and M1)


6-7 years

The second (m2 and M2)


12-13 years

Third (m3 and M3)


(7.5) 17-22 (28) years

Evaluation of skeletal age in different periods of ontogenesis is quite diverse: in prenatal period, the beginning and degree of formation of the diaphysis of long bones are evaluated; in the period of active growth - the size and morphology of individual bones; in the elderly - the severity of osteoporosis, osteophytes, marginal sprains on the vertebrae, on the phalanges of the fingers, etc .; during the entire ontogenesis, the features of the cellular microstructure of the bone (primarily the spongy substance of the long bones) and the articular surfaces of the vertebral bodies, as well as the peculiarities of the ossification of the growth zones of the long tubular bones and the degree of overgrowth of the cranial sutures. The widest application for determining the skeletal age in childhood and adolescence has found a way to assess the ossification of the bones of the wrist and wrist with the use of X-ray. A large number of developing bones with different maturation periods in these parts of the bone system and the relative ease of carrying out the research make this method accessible and informative. Approximate terms of ossification of the bones of the hand are given in Table. 2.8.

Table 2.8

Approximate terms of ossification of the bones of the hand


Term of ossification


2-3 years


3-4 years

Shaped and polygonal

5-6 years


10-12 years


12 bed (girls), 15 years old (boys)

Phalanges of fingers of a brush

11 years (girls), 13 years (boys)

The criteria for puberty are the time of appearance, the sequence and degree of development of secondary sexual characteristics, the harmony (consistency) of their appearance and development. The latter are determined using anthropometric indicators describing the parameters of the genitals, development of the mammary glands, changes in the pelvis, etc., sometimes using discrete characteristics estimated in points. The timing of appearance and the degree of development of individual characteristics during the pubertal period are quite individual, but the sequence of the onset of these changes with harmonious development is usually unchanged.

The criteria for puberty are informative during adolescence, puberty and adolescence. The standard terms for the appearance of secondary sexual characteristics are given in Table. 2.9, and the criteria of sexual maturity adopted in anthropology are given in the explanation to the table.

Table 2.9

The timing of the appearance of secondary sexual characteristics

Age, years




Rounding of the hips, wide pelvis




Folding of the scrotum


P1, A1

Increase in the size of the testicles (3 x 1.5 cm)


The appearance of the first menstruation

Pigmentation of the scrotum, A1, P1


Increasing the size of the clitoris, Ma2

Increase in the size of the testicles (3 x 1.5 cm) and penis (7 × 2.5 cm)


Establishing regular menstruation

Hair over the upper lip. Increased muscle strength. Body structure of the male type


Ma3, A2-3, P2-4

A2, P2


Hemorrhage of the cheeks, chin, thighs, voice mutation


Stopping Growth

Increase in the size of the testicles (3 x 2.5 cm) and penis (10 x 3 cm)


Hair on the shins, arms, chest. Stopping Growth

Symbols for the development of secondary sexual characteristics in girls:

1. Development of mammary glands (Ma - mammae): Ma0 - baby nipple; Ma1 - the nipple circle is exposed above the skin level; Ma2 is a large-sized sucking nipple, together with the nipple it forms a cone, the iron is slightly protruded above the skin; Ma3 - the iron is raised, the nipple and the nipple circle retain the shape of the cone; Ма4 - the nipple rises above the sucking mug, the gland takes the same shape and size as that of an adult woman.

2. The appearance of pubic hair (P - pubis): P0 - lack of hair; P1 - single short hair; P2 - the hair on the central part of the pubis is thicker, longer; P3 - long, thick hair, curly pubic in the entire triangle; P4 - the hair located on all area of ​​the pubis, pass to the hips, dense, curly, with a characteristic horizontal border.

3. Development of hair in the axilla (A - axillaris): A0 - lack of hair; A1 - single hair; A2 - the hair is more dense in the central part of the hollow; A3 - the hair is thick, long throughout the axillary region.

Symbols for the development of secondary sexual characteristics in boys:

1. Development of pubic hair: Р0 - absence of hair; P1 - individual straight hairs; P2 - thicker curly hair, upper border horizontal; P3 - dense pubic hair on the pubis and starting towards the navel; P4 - dense hair covering towards the navel and on the inner thighs.

2. Development of hair in the armpit: A0 - no hair; A1 - individual straight hairs; A2 - curly hair, but rare; A3 - dense hair, hair curly, pigmentation of anterior axillary fold.

Sometimes, to determine the biological age of children and adolescents, they use an assessment of their motor abilities, which are compared with existing standards characteristic of a particular age. However, this method has limited application, since it allows us to speak only of the infant's age of movement, which is important mainly in sports practice.

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