The wealth of knowledge in human growth and development has not come with ease rather it underwent laborious, prolonged and hazardous history of intellectual development. The scientific study of human growth probably began in the late eighteenth century with the oldest published record of the growth of a child by Count Philibert de Mountbeillard during the years 1759-1777 that was published in a supplement to the Histoire.Naturelle by Buffon. However, vauge idea of growth could be traced to the prehistory and early historic period where the rock paintings or the stone sculptures depicted humans in different ages and sex. Earliest written records on human growth and development come from Mesopotamia about 3500 years before present. Inscriptions communicate the act of fertilization, full term and premature birth and nine month pregnancy. Apprehension regarding low birth weight or prematurity, birth defects and twin births are also evidenced. Sumerians categorized the postnatal life into stages similar to modem concept of infancy, childhood, youth, adulthood and senescence. Though some art portray differences between size of a child and adult but there appears no direct substantiation of body measurement. Incidentally disproportional taller males as higher status than females as lower status are also portrayed in art. Positive relationship between health, social status and stature is there in several texts. All these reflect that both in Sumerian art and in life, there exists relationship between growth and biological conditions. Ancient Egyptian, Chinese, Hindu, Greek and Mesoamerican civilizations pursue many of these Sumerian traditions. Written records and art work indicating the earliest concern in the biology of children was prime interest with preservation of ‘life. Greek, Roman and Arab physicians recommend regimes of physical activity, education and diet promising health of children. All this meant that all human societies must converge on basic strategies for the care and feeding of their young. Egyptians and early Hindu, the early civilizations showed cautious concern for measurement of children and youth’s body. Egyptians used grid system for body proportions while Chinese and early Jewish traditions laid stress on spiritual aspects of human development in their concern for young. Ancient societies showed concern for stages of life which even today is very popular.
Considering the Latin West and the Renaissance scenario, three dimensional sculptures depicting the body dimensions of infants and children are portrayed with fair precision in Egyptian, Greek and Roman artwork. On observation of this art it strikes that infancy, childhood, youth and other ‘seven stages of life’ were pertinent to its biology and behaviour. The philosophy that there are seven stages of life continued following the collapse of Roman empire but with a difference; there appears to be shift in the status accorded to children and youths. Medieval physicians, clerks and artist believed that children were miniature adult; the growth and development of infant to adulthood required only an increase in size and maturity during growing years.
During medieval period there was no scientific approach to human growth and development. Renaissance period witnessed the resurgence of classical Greek concept of dynamics of growth though itnever could find place with Greek or Romans. It was Leonardo da Vinci ‘s idea that new studies in human body growth and development from conception onwards needs to be initiated. He commenced his study of a seven month fetus, the placenta and still born full term infants. Landmark event of human growth and development was Zerbis in 1502 publishing the anatomical difference between child and adult, followed later by several medical and scientific studies. Leonardo’s scientific work was depicted in his drawings of child and adult having right proportion. He infact developed the rule for drawing human proportion using Vitruvius, a first century architect. Diirur, a German, developed a technique using geometric transformations for deducing proportion of human head and face.
This enabled him to draw human variation in any size and proportion; infact he drew infants, children, women and men. Post-Renaissance, after 1600, painters infact depicted children with normal proportion and also with growth pathologies. Biological control of normal and pathological growth was not known at that time. It is not understood how scientists and physicians of that time considered different types of dwarfism.
As far as embryonic and fetal development is concerned much has been written about human growth’ and development prior to birth by Ancient, Classical and Medieval scholars. Though some information is based on actual observation of human and non-human fetus but mostly is result of imagination and myth. From fertilized ovum to the birth, the entire process is so contrary to the expectations based on our understanding of child growth after birth that earlier scholars were convinced that it actually occurred. William Harvey in 1951 proved that embryo is not preformed adult; rather there are series of embryological stages that are distinct in appearance from what we see just before or after birth. Leonardo da Vinci is credited with the first ever accurate drawing of the fetus and followed by descriptions of fetal anatomy and physiology by Vesalius in 1555 and Volcher Coiter in 1572.
The descriptions of fetal anatomy continued during the seventeenth and eighteenth century with most of the information based on last trimester of pregnancy. At this stage the fetus distinctly gives human appearance. Although now these studies are quite informative but they provided no answer to the physical changes that took place earlier in prenatal life. It was in 1799 that S. T. Sommerring published drawings of human embryo and fetus from fourth week post fertilization to fifth month which vividly showed that embryo is not a miniature adult. Karl Ernst Baer in 1829 described the germ layers-endoderm giving rise to internal organs, mesoderm forming the skeleton and muscles and ectoderm develops skin and teeth. Though Baer’s removed many misconceptions, yet it was not until twentieth century that an understanding was attained of the highly complex process occurring during prenatal growth.
Eighteenth Century Contributions
Longitudinal studies
The effect of early life events affecting later development was another interest post Renaissance. 1700s saw physicians interest in following the birth weight of the child viz-a-viz child’s health. Pre- and neonatal influences, on later development are interest of today’s researchers. This directed towards longitudinal studies which facilitated to study the relationship between early influences and its effect on growth. In this approach, same individual is examined at least twice with some time gap. Preceding the longitudinal study, it was cross-sectional study which was common practice and in which the individual is measured only once. The merit of crosssectional study is that it is faster and can be completed in short period of time, but has a demerit that the dynamics of the growth cannot be studied.
The Count Phillibert Gueneau du Montbeillard of France holds historical importance. He measured the height of his son since birth every six months till he was 18 years. George-Louie Lec1rec de Buffon included the measurements and his commentary on them which was the most famous study and also considered as first longitudinal study. The growth in height of the boy both in terms of attained stature by age and rate of growth were well documented graphically. The data was converted to modem units from obsolete French units by Scammon in 1922. The result, distance curve and velocity curve, became an integral part of growth studies. Another landmark eighteenth century longitudinal study was of Carlshule’s students, conducted between 1772 and 1794.
Political perception
Political and legal decision concerning the treatment of children came into picture for the first time in nineteenth century growth research. There was lot of influx of rural to urban migrants with the growth of European cities during eighteenth century resulting in dislocation from traditional rural family social organization in an urban setup. Subsequently, there was an increase in number of infants and children in the community- care and hospitals; and the growth and health of these abandoned children was extremely poor resulting in their death. Cadogan’s Essay echoed a general apprehension for infant’s health in England resulting a law being passed ensuing the working of foundling homes in 1767. Rousseau in his book Emile in 1762 advocated ‘return to nature’ including breast feeding of infants by their own mother since artificial feeding lead to many complexities due to hygiene issues. Industrial Revolution from 1765-1782, with James Watt developing steam engine, resulted in reduced necessity for human muscle power and the consequent employment of children for many tasks, which was not a good experience. Public health professionals, using height and weight as tools, then recognized a decline in child health that was related with urbanization and industrialization. There were many instances which suggested decline in health parameters for children. Acts came into action that regulated working hours and prohibited underage children being employed.
Nineteenth Century Contributions
Statistical methods .
Lambert Adolphe Quetelet published the first data of growth of height and weight of children which was statistically complete way back in 1835. He was the first researcher who made use of the concept of ‘normal curve’ which is now commonly referred as normal distribution curve. He used this to define the distribution of his growth measurements and emphasized the significance of measuring children rather than individuals to assess normal variation in growth. Subsequently, Luigi Pagliani in Europe followed Quetelets statistical approach beginning his studies on size and fitness of Italian military personnel. Later he applied his method to children and in 1876 proved that orphaned and abandoned boys in the ages 10-19 years when given care at a state-run agricultural colony improved in growth status and vital capacity. He also established that children of higher social classes faired better in height, weight and vital capacity when compared to poverty struck children.
Racial factor in growth
In United States a political debate necessitated the use of growth data. Henry Pickering Bowditch from 1875 collected data on height and weight of school-children taken by teachers. He described the differences in growth related to sex, nationality and socioeconomic level between his sample of children, applying modem statistical techniques and published series of reports later. It goes to the credit of Bowditch to construct percentile growth charts published in 1885. According to him, the children of labor class were smaller than those of non-Iabor class for which he preferred an environmental explanation rather than genetic. But this was not in agreement with Galton who had demonstrated the heritability of stature and other physical traits in his book Natural Inheritance in 1889. Galton’s work made some believe that heredity was all totally controlling the human form and functional proficiencies. Basically his work held importance to the supporters of eugenic movement which claimed to be capable of .improving human species by controlled breeding. Boas shattered the position of eugenicists with his study of migrants to United States and their children. Thereby, Bowditch and Boas demonstrated using statistical tools that eugenicists assertion that ethnicity could be determined by physical measurement was not true. Yet many eugenicists and politicians called for quotas on the so called inferior people into United States. Despite Boas presenting his report to US Congress, American Congress passed the ‘Immigration Restriction Acts’ in 1921 and 1924 which explicitly directed southern and eastern European and Asian for migration quota. Boas and environmentalist may have been unsuccessful in the political battle but their work inspired three generations of anthropologist, public health workers and epidemiologists and even others in related fields.
Twentieth Century Contributions
Boas’ scientific findings hold lots of importance; be it the methodology of growth studies or the significance of calculating growth velocities from the measurement of individual rather than sample means and even the concept of ‘tempo of growth’ to facilitate in understanding the difference between early and late maturing individuals. The first half of twentieth century witnessed contributions of several longitudinal studies from United States and Europe. Additionally, for better quantification of amounts and rates of growth of healthy children, technologies like radiology, physiology and psychology to characterize the biological maturation were used. Another aspect that emerged out of these longitudinal studies was the causes of individual differences between people; this probably was an outcome of Boas work on environment determinants of growth and physical development.
The American studies
Initially the American studies were financed by private donors particularly the Rockfeller Foundation and Laura Spellman Rockfeller Memorial Fund. ‘Lawrence K Frank maintained funds and assisted start and retained practically all major longitudinal studies. Ultimately longitudinal studies got its due recognition with United States National Research Council building Committee on Child Development in 1923 leading to several White House Conferences on Child Health. Publications of specialized journals, such as ‘Child Development’ in 1929 and ‘Growth’ in 1937, were the invaluable contributions to the cause of growth research. The study of normal growth, being of national importance both with its scientific and political value, gained momentum. Several important large scale long-term studies were initiated including the Fels Study, Harvard Growth Study, University of Iowa Child Welfare Station Study, University of Colorado Child Research Council Study, to name a few. The studies in general were interdisciplinary with physicians, psychologists, anthropologists and others; taking a global approach- they studied ‘the whole child’. They were particular in methodology of data collection, colleted data as an end in itself, never put forward any research question about human growth and they just planned to continue data collection for 15 years or more. Fels Longitudinal Study which began in 1929 was the only one which has survived till date, others disappeared for various reasons. The sample of Fels Study constituted healthy, well nourished boys and girls living in small urban communities and rural areas of southwestern Ohio. Participants were measured for weight, height and variety of other physical and psychological characteristics once a year from birth to maturity. According to Alex F Roche in 1992 Fels study remained feasible since the members of the staff were keen to use data, answering vital queries on human growth, development and health. Another landmark was the work of Frank K Shuttleworth who used Harvard Growth Study to design new statistical methods to analyze longitudinal data. In his first report in 1937 he used methods that are still used today. Works of Howard Meredith, Thomas Wingate Todd, Katherine Simmons, A R Behnke, Keys J Brozek, N. Bayley, R. E. Scammon and Boyd are landmark contributions in the field of Human Growth and Development. They are credited with immensely important work in this field and hold practical significance in current scenario too.
The European studies
European longitudinal growth research had a delayed start as compared to United States, probably due to the two World Wars. The 1920s witnessed two important longitudinal studies. Alexander Low conducted Aberdeen Scotland study in which he measured new born annually till they turned 5 years. Data was not analyzed appropriately till Tanner in 1956 gave correlation between measurements at different ages. Rachel Mary Fleming conducted the se ond longitudinal study and recorded annually stature and head dimensions of 3 to 18 years old individuals in England and Wales. In t933 her analysis included a longitudinal curve of growth in stature, head length and head breadth for all the participants and she noticed normal individual differences in mode and tempo of growth. She also observed the growth stunting eau ed by cornbir ation of inadequate food intake plus energy expended in commuting to school. E. M. Widdowson too found that negative emotional environment during chool mealtime could subdue physical growth. Fleming was responsible for changing social policy, particularly the introduction of free school lunch programs for undernourished children and necessity to identify such children. Longitudinal tudie by J. Ryle, R. Ache on, J. M. Tanner, R. Whitehouse along with British Harpendcn study and International Children Center sponsored studies are important milestones of research in Human Growth and Development in Europe.
Developing world- Longitudinal studies
International Children’s Center gave financial assistance for longitudinal studies in Africa, the Dakar and Kampala. By 1960s the data wa analyzed and some results were available with perplexing conclusions. There was no uniformity in the re ults of these studies as in some re pects African infants and children were advanced over Europeans and vice versa. Although. some assigned genetics as contributor to the difference but others looked more towards ecology. of human growth of Africa and its history – which actually meant poverty. Robert McVean in 1948 worked on longitudinal study of child, juvenile and adolescent development as the basic research project in a school. All the children who were attending the school were measured for weight, height, hand grip strength, eruption of permanent teeth, hand wrist X-ray take and several tests for cognitive development and school perfonnanc.e administered all under the Longitudinal tudy of Growth and Development of Guatemalan School Child. This became the first large-scale mixed longitudinal investigation of human growth. The highlight of the study was that the subjects of different starting ages were measured for several years, i.e. the overlap in ages meant that data covering much or all of the growing years may be composed injust a few years than in two decades. Lots of data was collected without much analysis, until American Anthropologist Barry Bogin entered the picture. His contribution includes adding tricep and sub capular skinfold and arm circumference to body composition for assessment of better nutritional status and adding Maya population in the study. American School Study and its enlarged successor was first major research program of its type in any developing nation. It is still continuing today making it the longest lived project of its kind. Programs of In titute of Nutrition of Central America and Panama (TNCAP) gave invaluable contribution in strengthening of Human Growth and Development studies.
Hormonal control
According to Tanner in 1960s there didn’t exist any entirely convincing and coherent theory of endocrinology of adolescence. Infact perception on endocrinology of growth at other stages of life: prenatal and postnatal was also not good. Way back in 1974, Melvin Grumbach and colleagues suggested several convincing and coherent theories on endocrinology of growth. This paved way for models and theories of hormonal control for all the other stages of growth. The technological advances in the evaluation of hormonal factors and progress in appreciating how hormones exert their influence on human growth and development are responsible for rapid research. The history of human growth hormones (HGh demonstrated in 1944) and insulinlike growth factors (TGFsfirst in 1957) are examples. Anthropological interest was generated by the breakthrough of human population differences due to the presence of these hormones-African pygmy appear to be d ficient of one of the lGF’s or its receptor. Endocrine glands like thyroid, adrenal, ovary and testis secrete hormones along with six hypothalamic and eight pituitary hormones and other growth factors regulate human growth. Initial information on hormone regulation was provided by children with endocrine pathologies. Non-invasive methods like using saliva instead of blood facilitates in including wider spectrum of normal children would enable in more detailed insight of endocrinology and growth.
Technological advancement and basic research concerning growth
Twentieth century saw the research into genetics of growth. The rediscovery of Mendelian laws in 1900 and the DNA characterizations in 1952 were probably two historical events that had bearing on growth research. Stress on ‘racial genetics’ paved way for modem population genetics by early 1950s. As a consequence of many genetic studies, the unraveling of impact of environment on growth was witnessed. There are a number of examples which you would be reading in following units to understand the impact of environment and genes on growth.
The technical foundation of growth research lies in the accuracy of instruments used for body measurements along with the standardized and reliable methodology. Invention of anthropometer by J S Elsholtz in 1654 was a landmark in growth research. Development of skinfold caliper, radiography, photogrammetry along with advances in data collection methodology and statistical treatment have taken growth research to different heights.
Inputs from the public health in 19th century and contribution of large scale longitudinal studies of 20th century provide invaluable data. Progress in molecular biology, nutrition, social sciences and endocrinology gave impetus to direct the study of human growth and development into research and medical specialty. The data and technical advances were primarily descriptive in nature describing how children grew and the effect of heredity and environment on growth, but were .unable to explain why. A theoretical approach was required to follow the ‘why’ of growth and development. Charles Darwin’s biological research became modem theoretical science and the scientific method of experimentation and hypotheses testing were progressively more applied to biological issues including the control of growth and development. With the passage of time theory of recapitulation gave way to growth theory which had contribution in late 19th and early 20th century from many scientists. Thompson stands out amongst all visualizing growth as movement through time. He interpreted vividly that growth velocities in stature or weight were only unique cases of a more universal biological process. Thomson is credited with developing the concept and methodology of using transformational grids to quantify the course of growth during the Jjfetime of an individual or evolutionary history of species, leading to providing an intellectual strength to growth and development research; and inspired subsequent generations of growth researchers to deliberate about growth in new ways.