Assignment Code: MANE 002/AST/TMA/2021-22

Course Code: MANE-002

Assignment Name: Human Growth and Development

Year: 2021-2022

Verification Status: Verified by Professor

Note: There are two sections ‘A’ and ‘B’. Attempt any five questions, at least two from each section. All questions carry equal marks. The word limit for 20 marks question is 500 words and that of 10 marks is 250 words.

Section A

Q1) Define growth and development. Discuss its aim and scope. (20)

Ans) In the context of children's physical development, growth refers to a child's increase in size, while development refers to the process by which the child's psychomotor skills develop. Medical concerns, such as the monitoring of physical and developmental changes, have also influenced growth studies. Progress of children's nutritional needs for normal growth, as well as the effects of the environment on growth and medical aspects of growth and its abnormalities. Understanding the interaction of growth and evolutionary biology in the human species is aided by the evolutionary study of growth.

Appreciating how humans grow, mature, and develop in their own niches is one of the best ways to explore the interaction of biology and culture in the human life course, because it is only during this phase that human beings experience and reflect both biology and sociocultural environments. Only by considering how a human develops from an embryo to an adult and investigating the forces at work during that process can we gain a better understanding of how biology and culture interact in our daily lives. The degree to which cultural factors interact with biological characteristics determined by genetics varies. The characteristics expressed in an individual are reflected in the e variable interactions. Without a doubt, some genetically based characteristics will manifest themselves regardless of the cultural context in which they are developed.

The interaction of environment and genes is reflected in characteristics such as intelligence, body shape, and growth. From the moment we are born, we have a genetic makeup that influences the maximum height we can reach in adulthood. However, in order to reach our full potential, we must be properly nourished during our formative years and avoid many childhood diseases and other stressors that stifle growth. One of the primary determinants of nutrition and health is socioeconomic status, which is a cultural factor. Understanding the human growth course, tracing its trajectories, and understanding its development either by comparison or on its own is the only way to comprehend the intricate effects of all these factors in isolation or in concert.

Similarly, knowing the human life course is necessary to understand human growth and development from an evolutionary perspective, with an interest in how natural selection has acted on the human life cycle from conception to death, a perspective known as life history theory. The majority of these life cycle stages represent biological transitions: the prenatal phase begins with conception and ends with birth; infancy is marked by nursing; childhood, or the juvenile phase, represents the period from weaning to sexual maturity (puberty in humans); adolescence is the period from puberty to the end of growth; adulthood is marked by the birth of the first child and/or the initiation of sexual activity; adulthood is marked by the birth of the first child and/or the initiation These biological markers are not only growth milestones for humans, but they also have cultural significance.

Puberty, for example, has different connotations in different cultures. In many cultures, a girl's first menstruation (menarche) is marked by ritual and celebration; this biological transition is often accompanied by a change in social status. It is also suggested that the adolescent stage of development provides benefits in terms of learning social skills prior to reproduction, indicating that the girl has matured. As a result, human adolescence is unique in that it has both biological and social dimensions. To comprehend the complex social implications of purely biological processes, it is necessary to understand why, when, and how these processes begin. Menopause is often associated with a rise in status for women in non-western societies, whereas it is commonly viewed as a negative transition for women in many Western societies. Growth, development, and health are influenced by collective and individual attitudes toward these life cycle transitions. To comprehend the human life cycle, these processes must be known and understood in terms of time, intensity, and space. Nutritional status, which may reflect an individual's health status, is also studied in human growth and development studies.

Q2) Discuss longitudinal method of studying growth. (20)

Ans) A well-designed growth study is required to monitor a population's health status. Prior to collecting data, careful thought should be given to the method of study, the time and cost involved in precise sampling procedures, and careful training in anthropometric measurements and statistical methods to be used for data analysis. It is critical to select the appropriate methods in order to gain a better understanding of the dynamics of human growth and average growth patterns. A longitudinal design over several years would be required to investigate variations during the adolescent growth spurt, allowing the time of initiation and peak of the spurt to be identified, as well as the magnitude of the spurt to be quantified. Researchers most commonly use cross-sectional or longitudinal methods to obtain age and gender specific growth data.

For a complete understanding of the growth processes, both types of methods are required. Longitudinal research involves making repeated observations on the same people at regular intervals over time. A mixed-longitudinal study is a third type of study in which a group of children is followed longitudinally, with some children leaving the study and others joining as new entrants at various age points. The longitudinal method refers to a study that uses the same child at different ages. Every child enrolled in the study is periodically measured for one or more body measurements at fixed intervals of time throughout the study period in this method of studying human growth. In other words, a longitudinal study entails making repeated observations on the same people at regular intervals over time. All children who were examined at the age of 5.0 years will have the same results as those who were examined at the age of 4.0 years.

The most important prerequisites of this method are the consistency of sample size and strict adherence to the specified periodicity at which children are to be followed lip. A longitudinal growth study can span any number of years. Individuals must only be measured twice a year to obtain the simplest type of velocity standards. Short-term longitudinal studies, such as those spanning the ages of 3 to 6, and full birth to maturity longitudinal studies, in which children are examined once, twice, quarterly, or even more times every year from birth until they are 20 years old or more, depending on the study's goal. Longitudinal studies are generally more useful during infancy and early childhood, as well as during adolescence. These are the two life stages that are marked by rapid growth and change.

A comprehensive longitudinal study's main disadvantage is that it takes a long time to complete and only a small number of subjects can be followed. To address these issues, 'linked longitudinal studies,' or studies spanning the ages of 0 to 6, 5 to 11, 10 to 15, 14 to 20, are conducted. The entire age range of human life's growing phase is spanned by this design in just six years. However, to obtain smooth joins of data collected at short intervals, efficient population sampling is required. Long-term longitudinal studies, even from birth to maturity, are required for an in-depth investigation of the relationship between continuously unfolding events in individuals and, very often, for clinical investigations of growth disorders. When calculating the results of each type of study, we must use the appropriate statistical methods.

Q3) Define and differentiate between any two of the following:

a) Negative secular trend and absent secular trend. (10)

Ans) A negative secular trend is children who are shorter, lighter, and mature later than previous generations. Guatemalans experienced a discriminant incidence of the negative trend from 1974 to 1983, a period of intense civil war and political repression. The mean stature of 10- and 11-year-old boys and girls from families of high, moderate, and very low socioeconomic status was found to be declining in cross-sectional samples. The main cause of the negative secular trend appears to be a general deterioration of Guatemala's quality of life, particularly the population's nutrition and health. Puberty is an important milestone in reproductive life, and changes in the timing of puberty over time may reflect a population's overall reproductive health. In the last four decades, a large cohort of Danish schoolchildren has shown secular trends in the age at pubertal growth spurt (OGS) and the age at peak height velocity (PHV) during puberty. Girls and boys' ages at OGS decreased by 0.2 and 0.4 years, respectively, whereas girls and boys' ages at PHV decreased by 0.5 and 0.3 years, respectively. A longitudinal study of Indian children and adolescents enrolled in the Sri Aurobindo International Centre of Education (SAICE) found that girls' OGS and PHV ages decreased over four decades, while boys' ages remained constant.

Positive Secular Trend

Children today are on average taller, heavier, and mature earlier than those of previous generations, indicating a positive secular trend. Haupsie and colleagues (1996) examined the evidence for secular trends in 17 countries, including Japan, Cuba, Brazil, North America, and Taiwan. They discovered that the Japanese experienced the strongest secular trend ever recorded for an entire nation following World War II. In 1950, the average height of Japanese young adult men was 160 cm; by 1995, it had risen to nearly 172 cm. Height increased at an average rate of 2.67 cm per decade over a 45-year period. In the first decade, the rate of change was much faster (about 4 cm) than in the last decade (about 1 cm). Between 1952 and 1985, the rate of secular height increase in Sweden and Norway was only 0.3 cm per decade. As evidenced by the adult trend in comparison to pre-pubertal children, positive secular changes in the height of children and adolescents are largely, but not entirely, related to earlier maturation. Increased obesity prevalence has been widely reported in almost all developed and developing countries in the last two to three decades, coinciding with a positive secular trend in height and a dramatic increase in childhood weight. The Pacific appears to have the highest prevalence of childhood obesity (approximately 20-30%), while parts of Southeast Asia and much of Sub-Saharan Africa appear to have the lowest rates.

b) Early-childhood and Mid-childhood (10)

Ans) Childhood is a period of post-weaning dependency and relative growth stability. may be classified into three sub-stages based on its own pattern of growth, feeding behaviour, motor development, and cognitive maturation:

Early Childhood

With the start of childhood, the rapid decline in growth rate that occurs during childhood comes to an end, resulting in slow and steady growth during this time. Because of their immature dentition, small digestive system, and rapid brain growth, children require specially prepared foods. Because of their susceptibility to disease and a lack of food, they are more likely to rely on their elders. As a result of neurological development, the child's psychomotor skills improve, and by the end of this phase, he or she is able to comprehend language as well as social, physical, and cultural norms. When physical and cognitive growth is slow, learning is more efficient. In terms of physical growth, females outgrow males and are taller than their male counterparts.

Mid-Childhood Postnatal Growth

This is the most stable period, with different rates of growth in different body parts and changes in body proportion, by the age of nine years. For example, as people get older, the ratio of sitting height to stature decreases, indicating that the lower extremities grow faster than the trunk. In other words, as people grow older, sitting height becomes less important in determining their stature. The replacement of milk teeth by permanent teeth begins with the eruption of the first (permanent) molar, which occurs on average around 6 years in most human populations. Most children have all four first molars by the end of this phase, with the exception of the 2nd molar, which erupts at the age of 12. The permanent incisors and canines also erupt at this time. In terms of dental development, the child learns to process a diet similar to that of an adult. By the age of ten, a child has grown by 96 percent, and only four percent growth is required until the age of twenty. It's also worth noting that until around the age of 11, females continue to outgrow males in most body dimensions, after which males outgrow them and remain ahead throughout their lives.

After studying hundreds of hours of films of motor activity in longitudinal studies of children aged birth to nine years, Arnold Gesell concluded that motor development and thus physical growth proceeded in two directions during the prenatal period, infancy, and childhood:

1. The head is controlled first, then the arms and trunk, and finally the legs. This is known as the head-to-tail sequence or cephalocaudal trend.

2. Control of the head, trunk, and arms takes precedence over coordination of the hands and fingers in the Caudocephalic (proximo-distal) trend.

3. According to Gesell, maturation, which is linked to the development of the central nervous system and muscular development, is the sole determinant of motor development.

Section B

Q4) Briefly discuss lifestyle factors affecting human growth. (20)

Ans) It will be possible to understand the lifestyle-related factors that influence the nature and extent of fatal growth if the lifestyle of pregnant women is taken into account while studying the effect of lifestyle on pre-natal growth. The environment in which the foetus grows in the woman's womb must be favourable for survival and normal development. According to a recent study conducted in the Netherlands, maternal lifestyle habits have an impact on early fatal growth as measured by crown-to-rump length. During the first trimester of pregnancy, it was discovered that mothers who smoked and did not take adequate folic acid supplements had foetuses with shorter crown-to-rump lengths than those who did not smoke and took adequate folic acid supplements. It also stated that fatal growth retardation in the first trimester is linked to an increased risk of adverse birth outcomes, as measured by low birth weight (less than 2500 g) and early childhood growth acceleration.

It can be deduced from the preceding that maternal lifestyle has a significant impact on the nature and extent of the prenatal growth profile. It is also recognised that the outcome of prenatal growth, or fatal growth, is assessed by fatal length and weight at birth—a crucial indicator of fatal growth; however, weight is given greater weight because fatal prognosis is dependent on increase in fatal weight. Birth is undeniably the event in which the foetus exits the uterus and emerges into a changing external environment, emphasising birth weight as the most important indicator of the new-physical born condition. Most of the factors that influence intrauterine outcome as measured by birth weight are known to be linked to maternal lifestyle, as evidenced by maternal nutrition, maternal substance use, and so on.

Intrauterine growth retardation is thought to be caused by a number of factors. Tobacco use and maternal malnutrition, as manifested by low energy intake, insufficient micronutrient consumption, and consequently low weight gain, are the most significant issues in developing countries, including India. There is a difference in maternal undernutrition between rural and urban areas, resulting in a different prevalence of small-for-date infants. This is because the vast majority of rural women in developing countries have low energy intake or low weight gain, in addition to low prepregnant weight and a history of childhood and adolescent under-nutrition, owing to low socioeconomic backgrounds combined with socio-cultural practises. These conditions make it easier for women with these characteristics to have "small-for-date infants."

Lifestyle and Post-Natal Growth

The foetus is exposed to the external environment as a result of birth, and the baby begins to adjust and adapt to the newly introduced external environment by constantly interacting with it shortly after birth. To become an adult, a person goes through a series of stages. A human being grows into adulthood over the course of 19 to 20 years, during which time he or she is subjected to a complex biological process known as physical growth and maturation. It is well known that human development is the result of complex interactions between the biological endowment of human species, the physical environment in which human individuals live, and the socioeconomic and political environment that each human group creates as a cultural being. People have been migrating from one place to another since the beginning of time. People are forced to migrate from one place to another for perceived or real-life reasons due to demographic, economic, and political factors. This, in turn, causes changes in the physical, biological, and social environments, resulting in changes in many aspects of life and, as a result, changes in growth patterns. Urbanization is an important aspect of development in today's developing world, and the process is gaining traction with each passing year. As a result, a large number of people are continuously migrating from rural to urban areas, resulting in a change in their lifestyle, which has an impact on their health and growth profiles.

Q5) What do you understand by Concept of nutrition and cultural practices? (20)

Ans) In most countries, social factors and cultural practises have an impact on what people prefer to eat. In many countries, practises are specifically designed to protect and support good health, such as providing rich, energy-dense foods to women in the first months after childbirth. However, it is true that some traditional food practises and taboos in some societies may contribute to nutritional deficiencies in certain populations. Traditional food practises may not always be scientifically sound, resulting in a well-balanced diet; and cultural taboos surrounding certain essential food items in some societies can result in malnutrition due to nutritional deficiencies.

Nutrition: Parental Choice

Food preferences are shared by children and adolescents all over the world with their parents rather than their friends in general. Parents have made the majority of food choices for their children since birth, which may be influenced by the foods available in their environment. Although there is diversity within a culture, most parents share some food preferences. Why do children and adolescents around the world share their food preferences with their parents instead of their peers? Food intake in humans is culturally conditioned rather than entirely biological or natural. A human baby grows up in a family, learning to speak and becoming familiar with the dos and don'ts of society. Similarly, the baby becomes accustomed to 'what to eat and what not to eat' as dictated by the parents and family norms. After initial cultural patterning, a baby leaves the family and meets up with friends who have been culturally conditioned by their own families. Perhaps this is why children share their food preferences with their parents rather than their peers.

Unusual feeding practices of the new-born

In most countries, there are differences in the feeding practises of newsboys at birth depending on whether they are delivered in a medical centre or at home. Ethiopian newsboys, according to Aboud, should be given a spoonful of soft rancid butter or warm water with sugar to oil the pipes and sweeten the vocal cords before giving breast milk. Unfortunately, many new urban mothers believe they don't have enough milk and that their baby requires more nutrients to grow. As a result, they frequently supplement breastfeeding in the first few months with other foods and liquids such as cereal, fruit, cow's milk, and tea, which reduces the mother's milk flow. It's important to remember that breast milk alone provides everything an infant requires. In the first three months, 9 percent of mothers in Turkey, 50% in India, and 84 percent in Ethiopia exclusively breastfeed their babies.

Weaning food practices

Some societies prefer to wean their babies by introducing solid food early, while others prefer the opposite. Many mothers in Africa and Asia believe that one should wait until their children have teeth at the age of one year before giving them solid food. Others believe that a specific type of traditional food that is high in mass but low in calories will satisfy the hunger of children. Malnutrition is a result of both diets. Fruits and vegetables, as well as, in some cases, milk, are the most commonly missing foods from children's diets in most countries. Even in tropical climates where fruits and vegetables abound, there is a widespread belief that fruits and vegetables cause diarrhoea in children. Of course, one day of loose stools is not the same as three days of watery stools. Furthermore, children in rural developing areas rarely drink cow's milk once breastfeeding has ended.

Q6) Describe in brief various methods of assessment of body composition. (20)

Ans) The various methods of assessment of body composition are as follows:

Densitometry

The density of a body (Db) is equal to the ratio of its mass (MA) to its volume (V): Db=MA/V.

It is inversely proportional to body fat percentage: the higher the fat percentage, the lower the body density. As a result, body density can be used to calculate the percentage of body weight that is fat. The procedure of estimating body composition from body density is known as densitometry. It entails the following procedures:

Hydro Densitometry or Under Water Weighing (UWW)

The subject's weight is first measured in air, then while completely submerged in water after maximum expiration. The volume of the body is calculated using Archimedes' principle, which states that when a body is immersed in a fluid, the weight "lost" is equal to the weight of the fluid displaced by a buoyancy force. When a subject is submerged in water, body volume (BV) equals weight loss in water, corrected for water density corresponding to the temperature at the time of submersion.

BV = (Wa - Ww)/Dw

The subject's weight in air and water is represented by Wa and Ww, respectively. It is preferred that the subjects be fasted and that measurements be taken under conditions of maximum expiration in a practical situation.

Air Displacement Plethysmography

The technique of air displacement plethysmography is an alternative to underwater weighing for estimating body volume and thus body fat (ADP). The volume of an object is indirectly measured in ADP by measuring how much air it displaces inside an enclosed chamber (plethysmograph). When a subject sits inside the chamber and displaces a volume of air equal to his or her body volume, the human body volume is measured. The volume of air remaining inside the chamber when the subject is inside is subtracted from the volume of air in the chamber when it is empty to calculate body volume indirectly. This technique is used by the BOD POD, a relatively new device.

Hydrometry

The highest percentage of body mass is made up of water. Total body water (TBW) makes up 73 percent of the FFM and 60 percent of body weight in healthy adults. These fractional contents, on the other hand, vary with age and disease. The TBW of a healthy infant is typically 80-83 percent of FFM, declining rapidly over the next 3-5 years until the hydration fraction reaches that of adults. Dehydration causes a 15% reduction in body water, which results in a significant change in body weight and can be life-threatening. This emphasises the importance of determining TBW as a component of body composition.

Dilution Method

The volume of a compartment is equal to the ratio of the dose of tracer, administered orally or intravenously, to its concentration in that compartment within a specified time after the administration of the dose, according to the dilution principle.There are four basic assumptions that come with the dilution technique:

1. The tracer is only found in the body's water.

2. It is distributed evenly throughout all anatomical water compartments.

3. The tracer's equilibration occurs quickly.

4. During tracer equilibration, neither the tracer nor the body water are metabolised.

The basic dilution techniques used to measure ECW volume are the same as those used to measure TBW volume, with the exception of the tracer. Due to differences in bromide concentrations in different fluids, the most commonly used tracer is non-radioactive bromine (Br), and sampling is limited to blood plasma. Although a few researchers have used X-ray fluorescence, spectrophotometer, or mass spectrometry techniques, the most common analytical Br assay is high-pressure liquid chromatography.