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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,〔(【引用サイトリンク】url=https://www.stadiometer.com/ )〕 usually in centimetres when using the metric system, or feet and inches when using the imperial system. When populations share genetic background 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.〔Ganong, William F. (2001) ''Review of Medical Physiology'', Lange Medical, pp. 392–397, ISBN 0071605673.〕 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. ==Determinants of growth and height== The study of height is known as auxology.〔Hermanussen, Michael (ed) (2013) ''Auxology – Studying Human Growth and Development'', Schweizerbart, ISBN 9783510652785.〕 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 in regard to differences among populations. Average height is relevant to the measurement of the health and wellness (standard of living and quality of life) of populations. 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 are relatively equally distributed. Changes in diet (nutrition) and a general rise in quality of health care and standard of living are the cited factors in the Asian populations. Average height in the United States has remained essentially stagnant since the 1980s even as the genetic and ethnic background of residents has shifted. Malnutrition including chronic undernutrition and acute malnutrition is known to have caused stunted growth in various populations. This has been seen in North Korea, parts of Africa, certain historical Europe, and other populations. Developing countries such as Guatemala have rates of stunting in children under 5 living as high as 82.2% in Totonicapán, and 49.8% nationwide. Height measurements are by nature subject to statistical sampling errors even for a single individual. In a clinical situation, height measurements are seldom taken more often than once per office visit, which may mean sampling taking place a week to several months apart. The smooth 50th percentile male and female growth curves illustrated above are aggregate values from thousands of individuals sampled at ages from birth to age 20. In reality, a single individual's growth curve shows large upward and downward spikes. Partly due to actual differences in growth velocity, and partly due to small measurement errors. For example, a typical measurement error of plus or minus 0.5 cm may completely nullify 0.5 cm of actual growth resulting in either a "negative" 0.5 cm growth (due to overestimation in the previous visit combined with underestimation in the latter), up to a 1.5 cm growth (the first visit underestimating and the second visit overestimating) in the same elapsed time period between measurements. Note there is a discontinuity in the growth curves at age 2, which reflects the difference in recumbent length (with the child on his or her back), used in measuring infants and toddlers and standing height typically measured from age 2 onwards. Height, like other phenotypic traits, is determined by a combination of genetics and environmental factors. A child's height based on parental heights is subject to regression toward the mean, therefore extremely tall or short parents will likely have correspondingly taller or shorter offspring, but their offspring will also likely be closer to average height than the parents themselves. Genetic potential and a number of hormones, minus illness, is a basic determinant for height. Other factors include the genetic response to external factors such as diet, exercise, environment, and life circumstances. Humans grow fastest (other than in the womb) as infants and toddlers, rapidly declining from a maximum at birth to roughly age 2, tapering to a slowly declining rate, and then during the pubertal growth spurt, a rapid rise to a second maximum (at around 11–12 years for female, and 13–14 years for male), followed by a steady decline to zero. On average, female growth speed trails off to zero at about 15 or 16 years, whereas the male curve continues for approximately 3 more years, going to zero at about 18–20. These are also critical periods where stressors such as malnutrition (or even severe child neglect) have the greatest effect. 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.〔 The pregnant mother's health is important 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 influences 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.〔(Table 1. Association of 'biological' and demographic variables and height. Figures are coefficients (95% confidence intervals) adjusted for each of the variables shown ) in 〕 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.〔〔 The precise relationship between genetics and environment is complex and uncertain. Differences in human height is 60%–80% heritable, according to several twin studies and has been considered polygenic since the Mendelian-biometrician debate a hundred years ago. A genome-wide association (GWA) study of more than 180,000 individuals has identified hundreds of genetic variants in at least 180 loci associated with adult human height. The number of individuals have since been expanded to 253,288 individuals and the number of genetic variants identified is 697 in 423 genetic loci. In a separate study of body proportion using sitting-height ratio, it reports that these 697 variants can be partitioned into 3 distinct classes, (1) variants that primarily determine leg length, (2) variants that primarily determine head and/or torso length, or (3) variants that affect overall body size, i.e. have no effect on body proportion, which gives insights into the biological mechanisms underlying how these 697 genetic variants affect overall height. 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 only in height and the women averaged . Bogin took another series of measurements after the Guatemalan Civil War had erupted, during which up to a million Guatemalans had 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. By 2000, the American Maya were taller than the Guatemalan Maya of the same age, largely due to better nutrition and health care.〔 Bogin also noted that American Maya children had a significantly lower sitting height ratio, (i.e., relatively longer legs, averaging longer) than the Guatemalan Maya. The Nilotic peoples of Sudan such as the Shilluk and Dinka have been described as some of the tallest in the world. Dinka Ruweng males investigated by Roberts in 1953–54 were on average tall, and Shilluk males averaged . The Nilotic people are characterized as having long legs, narrow bodies and short trunks, an adaptation to hot weather. However, male Dinka and Shilluk refugees measured in 1995 in Southwestern Ethiopia were on average only 1.764 m and 1.726 m tall, respectively. In Tibet, the khampas are known for their great height. Khampa males are on average 180 cm tall (5 ft 11 in). Anthropologist Michael Peissel described the Khampa in 1964: "The Khampas stood a good six feet in height." The people of the Dinaric Alps (South Slavs) are on record as being the tallest in the world, with a male average height of 185.6 cm (6 ft 1.1 in) and female average height of 170.9 cm (5 ft 7.3 in). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「human height」の詳細全文を読む スポンサード リンク
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