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Human height is a measurement of the length of a human's body, from the bottom of the feet to the top of the head, when standing erect. It is still not demonstrated on what time on a day humans should get measured because the spine shrinks during the day and that makes people almost one inch shorter in the evening than in the morning. Most readily sources tell that the best time to measure is in the forenoon because most people get measured on that time during physical examinations at school or by the doctor. The morning height is mostly being ignored because a human is stretched out of bed, in the morning for a short time. About 5 hours after being awake, the human is already at his lowest height. The eventual height of an adult human is dependent on both hereditary and environmental factors. The particular human genome that an individual inherits is a large part of the first variable ("nature") and a combination of health and other environmental factors present before adulthood (when growth stops) are a major part of the second determinant ("nurture"). Hereditary factors include both genes and chromosomes, and are inborn. Environmental factors are events that occur before adult height is reached, such as diet, exercise, disease and living conditions.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 usually due to gigantism or dwarfism; which are medical conditions due to specific genes or to endocrine abnormalities. In regions of extreme poverty or prolonged warfare, environmental factors like malnutrition during childhood or adolescence may account for marked reductions in adult stature even without the presence of any of these medical conditions. This is one reason that immigrant populations from regions of extreme poverty to regions of plenty may show an increase in stature, despite sharing the same gene pool.[citation needed]The average height for each sex within a population is significantly different, with adult males being (on average) taller than adult females. Women ordinarily reach their greatest height at a younger age than men, as puberty generally occurs several years earlier in young women than in young men. Vertical growth stops when the long bones stop lengthening, which occurs with the closure of epiphyseal plates. These plates are bone growth centers that disappear ("close") under the hormonal surges brought about by the completion of puberty. Adult height for one sex in a particular ethnic group follows more or less a normal distribution. |
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