Methods of Studying Human Growth
Process of human growth starts from conception and continues till the child grows into a fully mature adult. Growth is characterized by net increase in size/mass of tissues and development signifies maturation of organs and of functions.
Human Growth and development are influenced by genetic, functional, environmental, nutritional, metabolic, social, emotional and cultural factors to a great extent. The process can be assessed by taking into account the increase in height and weight as an entity, when studied longitudinally. Pace of these changes taking place varies from person to person.
In some individuals the developmental changes might appear earlier while among others same might take place at a slow rate. One aspect of growing children that gets noticeable by all of us at school is the fact that in the same class of children some look very young while some look mature then the others, with one group in-between.
This observation makes one wonder if there is some other way to assess biological maturation. Even in adulthood, people of the same chronological age, look younger or older than their peers here, it is important to introduce the fact that human body have two types of age – chronological age and biological age.
Chronological V/s Biological Age
Chronological age is the one we all are familiar with. It is calculated by the number of years denoted by Earth‘s revolutions around the sun. It is the current age in years, calculated from the birth date. Chronological age is the actual number of years a person has lived in years, months, days, or a combination of all of these; for example 15 years, 3 months, and 12 days.
Biological age, on the other hand, represents the biological status of maturity referring to how old a person seems to be. It is an individual’s development based on certain biomarkers – a recordable molecular or cellular event.
Biological age, also called physiological age, determines the extent of body functioning relative to actual calendar age. For example, one may have a calendar or chronological age of 65, but because of healthy and active lifestyle, avoiding longevity threats like consumption of tobacco or subjection to obesity, that person is physiologically more similar to someone with a chronological age of 55.
In that case, his/her biological age would, therefore, be 55. So, the biological age is a measure of how time and lifestyle have affected the organs and cells compared to other people of the same chronological age.
Factors Determining Biological Age
There exist several factors that can determine/influence the biological age of an individual, but none of these are definitive or accurate, rather that would give years on an average life expectancy.
1. Lifestyle
Healthy living habits have significant impact on longevity and extended biological age. These majorly include exercise/physical activeness, eating/dietary habits, stress levels, alcohol/tobacco consumption, level of education, amount of sleep, sexual/romantic relationships.
Enough of physical activity, dietary pattern constituting more of nutrient-rich content and less of fatty entities, less or no stress and keeping it away from drinking and smoking tend to influence longevity in positive terms. Decreased biological age has been found associated with lower educational background and lesser hours of sleep.
2. Heredity
Genetic predisposition/vulnerabilities are another major factor responsible for influencing biological age. Heredity/gene pool contributes to increased biological age that has nothing to do with lifestyle habits. Just as the way specific diseases run in families, longevity also does.
If a person has family members who have lived longer than 96 years, chances are that the person would also lead a longer life- even if his/her lifestyle patterns are less than healthy.
3. Habitat/Geographical Nativity
Another important factor influencing biological age is the place where you live. There lies no secret in the fact that the environment and culture one lives in is directly linked to the person‘s healthy living.
Determination of Biological Age
1. Anthropological Assessment
Weight and height are physical manifestations of growth and development. They are utilized the most in diagnostic procedures and in assessment of growth and development. Body mass is probably the best criterion of nutrition and growth because it sums up all increments in size.
By comparing the height and weight of a child of a given age with the standard height weight values of the same age group, one can assess the relative growth rate as well as the factors responsible.
2. Skeletal Assessment
The skeletal maturity of the individual is known as bone age. Bone age is an appropriate indicator of physiological development and is distinct from the chronological age. Appearance and fusion of different skeletal centres of ossification follows a fairly definite pattern and time schedule from birth to maturity.
3. Dental Assessment
The development and eruption of teeth are part of child′s total development. Tooth eruption and development is a useful measure of maturity as it represents a series of recognizable events which take place in the same sequence from birth to maturity.
