vannfra vishwesh myrrine
Novella Poinsett
Human height or stature is the distance from the bottom of the feet to the top of the head in a human body, standing erect. It is measured using a stadiometer,[1] in centimetres when using the metric system or SI system,[2][3] or feet and inches when using United States customary units or the imperial system.[4][5]
Height is also important because it is closely correlated with other health components, such as life expectancy.[6] Studies show that there is a correlation between small stature and a longer life expectancy. Individuals of small stature are also more likely to have lower blood pressure and are less likely to acquire cancer. The University of Hawaii has found that the "longevity gene" FOXO3 that reduces the effects of aging is more commonly found in individuals of small body size.[7] Short stature decreases the risk of venous insufficiency.[8]
When populations share genetic backgrounds and environmental factors, average height is frequently characteristic within the group. Exceptional height variation (around 20% deviation from average) within such a population is sometimes due to gigantism or dwarfism, which are medical conditions caused by specific genes or endocrine abnormalities.[9]
The development of human height can serve as an indicator of two key welfare components, namely nutritional quality and health.[10] In regions of poverty or warfare, environmental factors like chronic malnutrition during childhood or adolescence may result in delayed growth and/or marked reductions in adult stature even without the presence of any of these medical conditions.
Growth has long been recognized as a measure of the health of individuals, hence part of the reasoning for the use of growth charts. For individuals, as indicators of health problems, growth trends are tracked for significant deviations, and growth is also monitored for significant deficiency from genetic expectations. Genetics is a major factor in determining the height of individuals, though it is far less influential regarding differences among populations. Average height is relevant to the measurement of the health and wellness standard of living and quality of life of populations.[12]
Moreover, the health of a mother throughout her life, especially during her critical period and pregnancy, has a role. A healthier child and adult develops a body that is better able to provide optimal prenatal conditions.[17] The pregnant mother's health is essential for herself but also the fetus as gestation is itself a critical period for an embryo/fetus, though some problems affecting height during this period are resolved by catch-up growth assuming childhood conditions are good. Thus, there is a cumulative generation effect such that nutrition and health over generations influence the height of descendants to varying degrees.
The age of the mother also has some influence on her child's height. Studies in modern times have observed a gradual increase in height with maternal age, though these early studies suggest that trend is due to various socio-economic situations that select certain demographics as being more likely to have a first birth early in the mother's life.[18][19][20] These same studies show that children born to a young mother are more likely to have below-average educational and behavioural development, again suggesting an ultimate cause of resources and family status rather than a purely biological explanation.[19][20]
In 1988 it was observed that first-born males were shorter than later-born males.[21] However, in 2013 the reverse observation was made.[22] The study authors suggest that the cause may be socio-economic in nature.
The effect of environment on height is illustrated by studies performed by anthropologist Barry Bogin and coworkers of Guatemala Mayan children living in the United States. In the early 1970s, when Bogin first visited Guatemala, he observed that Mayan Indian men averaged 157 cm (5 ft 2 in) in height and the women averaged 142 cm (4 ft 8 in). Bogin took another series of measurements after the Guatemalan Civil War, during which up to a million Guatemalans fled to the United States. He discovered that Maya refugees, who ranged from six to twelve years old, were significantly taller than their Guatemalan counterparts.[28] By 2000, the American Maya were 10.24 centimetres (4.0 in) taller than the Guatemalan Maya of the same age, largely due to better nutrition and health care.[29] Bogin also noted that American Maya children had relatively longer legs, averaging 7.02 centimetres (2.8 in) longer than the Guatemalan Maya (a significantly lower sitting height ratio).[29][30]
Attributed as a significant reason for the trend of increasing height in parts of Europe are the egalitarian populations where proper medical care and adequate nutrition had been relatively equally distributed as of 2004.[34] The uneven distribution of nutritional resources makes it more plausible for individuals with better access to resources to grow taller, while individuals with worse access to resources have a lessened chance of growing taller.[35]
Changes in diet (nutrition) and a general rise in quality of health care and standard of living are the cited factors in Asian populations. Malnutrition including chronic undernutrition and acute malnutrition is known to have caused stunted growth in various populations.[36] This has been seen in North Korea, parts of Africa, certain historical Europe, and other populations.[17] Developing countries such as Guatemala have rates of stunting in children under 5 living as high as 82.2% in Totonicapn, and 49.8% nationwide.[37]
Average height in a nation is correlated with protein quality. Nations that consume more protein in the form of meat, dairy, eggs, and fish tend to be taller, while those that obtain more protein from cereals tend to be shorter.[citation needed] Therefore, populations with high cattle per capita and high consumption of dairy live longer and are taller. Historically, this can be seen in the cases of the United States, Argentina, New Zealand and Australia in the beginning of the 19th century.[38] Moreover, when the production and consumption of milk and beef is taken to consideration, it can be seen why the Germanic people who lived outside of the Roman Empire were taller than those who lived at its heart.[39]
Studies show that there is a correlation between small stature and a longer life expectancy. Individuals of small stature are also more likely to have lower blood pressure and are less likely to acquire cancer. The University of Hawaii has found that the "longevity gene" FOXO3 that reduces the effects of aging is more commonly found in individuals of a small body size.[7] Short stature decreases the risk of venous insufficiency.[8] Certain studies have shown that height is a factor in overall health while some suggest tallness is associated with better cardiovascular health and shortness with longevity.[40] Cancer risk has also been found to grow with height.[41] Moreover, scientists have also observed a protective effect of height on risk for Alzheimer's disease, although this fact could be a result of the genetic overlap between height and intracraneal volume and there are also genetic variants influencing height that could affect biological mechanisms involved in Alzheimer's disease etiology, such as insulin-like growth factor 1 (IGF-1).[42]
Nonetheless, modern westernized interpretations of the relationship between height and health fail to account for the observed height variations worldwide.[43] Cavalli-Sforza and Cavalli-Sforza note that variations in height worldwide can be partly attributed to evolutionary pressures resulting from differing environments. These evolutionary pressures result in height-related health implications. While tallness is an adaptive benefit in colder climates such as those found in Europe, shortness helps dissipate body heat in warmer climatic regions.[43] Consequently, the relationships between health and height cannot be easily generalized since tallness and shortness can both provide health benefits in different environmental settings.
In the end, being excessively tall can cause various medical problems, including cardiovascular problems, because of the increased load on the heart to supply the body with blood, and problems resulting from the increased time it takes the brain to communicate with the extremities. For example, Robert Wadlow, the tallest human known to verifiable history, developed difficulty in walking as his height increased throughout his life. In many of the pictures of the latter portion of his life, Wadlow can be seen gripping something for support. Late in his life, although he died at age 22, he had to wear braces on his legs and walk with a cane; and he died after developing an infection in his legs because he was unable to feel the irritation and cutting caused by his leg braces.
Sources are in disagreement about the overall relationship between height and longevity. Samaras and Elrick, in the Western Journal of Medicine, demonstrate an inverse correlation between height and longevity in several mammals including humans.[40]
In medicine, height is measured to monitor child development, this is a better indicator of growth than weight in the long term.[47] For older people, excessive height loss is a symptom of osteoporosis.[48] Height is also used to compute indicators like body surface area or body mass index.
There is a large body of research in psychology, economics, and human biology that has assessed the relationship between several physical features (e.g. body height) and occupational success.[49] The correlation between height and success was explored decades ago.[50][51] Shorter people are considered to have an advantage in certain sports (e.g. gymnastics, race car driving, etc.), whereas in many other sports taller people have a major advantage. In most occupational fields, body height is not relevant to how well people are able to perform; nonetheless several studies found that success was positively correlated with body height, although there may be other factors such as sex or socioeconomic status that are correlated with height which may account for the difference in success.[49][50][52][53]
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