question: Why has the average height of humans drastically increased over the past 100 years? How tall will humans be in 100 years? What about the year 3000? Is there a height that our bodies will definitely cap out at?
comment: The real answer here is better nutrition. There hasn’t been enough time for it to be an evolutionary thing. People just used to have much more sporadic access to food, and often of lower quality which stunted their growth. Food is now plentiful and easily accessible in much of the world, so people are more likely to reach or get close to their maximum potential height than was the case in the past. In any timescale of hundreds or even thousands of years, you aren’t likely to see people get a lot taller than the tallest populations that you find today.
passages: 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 for herself but also for 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 influences the height of descendants to varying degrees.
   Section::::External links.
  
  BULLET::::- CDC National Center for Health Statistics: Growth Charts of American Percentiles
  
  BULLET::::- fao.org, Body Weights and Heights by Countries (given in percentiles)
  
  BULLET::::- The Height Gap, Article discussing differences in height around the world
  
  BULLET::::- Tallest in the World: Native Americans of the Great Plains in the Nineteenth Century
  
  BULLET::::- European Heights in the Early eighteenth Century
  
  BULLET::::- Spatial Convergence in Height in East-Central Europe, 1890–1910
  
  BULLET::::- The Biological Standard of Living in Europe During the Last Two Millennia
  
  BULLET::::- HEALTH AND NUTRITION IN THE PREINDUSTRIAL ERA: INSIGHTS FROM A MILLENNIUM OF AVERAGE HEIGHTS IN NORTHERN EUROPE
   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 18–19. These are also critical periods where stressors such as malnutrition (or even severe child neglect) have the greatest effect.
   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. Average (male) 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 attain more protein from cereals tend to be shorter. 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. 
   BULLET::::- The height of persons can vary over the course of a day, due to factors such as a height decrease from exercise done directly before measurement (i.e. inversely correlated), or a height increase since lying down for a significant period of time (i.e. positively correlated). For example, one study revealed a mean decrease of in the heights of 100 children from getting out of bed in the morning to between 4 and 5 p.m. that same day. Such factors may not have been controlled in some of the studies.
  
  Note: Letters in grey indicate non-measured height.
  
  Section::::External links.
   BULLET::::- The height of persons can vary over the course of a day, due to factors such as a height increase from exercise done directly before measurement (normally inversely correlated), or a height increase since lying down for a significant period of time (normally inversely correlated). For example, one study revealed a mean decrease of in the heights of 100 children from getting out of bed in the morning to between 4 and 5 p.m. that same day. Such factors may not have been controlled in some of the studies.
   Section::::History of human height.
  
  In the 150 years since the mid-nineteenth century, the average human height in industrialised countries has increased by up to . However, these increases appear to have largely levelled off. Before the mid-nineteenth century, there were cycles in height, with periods of increase and decrease; however, examinations of skeletons show no significant differences in height from the Stone Age through the early-1800s.
   A large body of human and animal evidence indicates that shorter, smaller bodies age slower, and have fewer chronic diseases and greater longevity. For example, a study found eight areas of support for the "smaller lives longer" thesis. These areas of evidence include studies involving longevity, life expectancy, centenarians, male vs. female longevity differences, mortality advantages of shorter people, survival findings, smaller body size due to calorie restriction, and within species body size differences. They all support the conclusion that smaller individuals live longer in healthy environments and with good nutrition. However, the difference in longevity is modest. Several human studies have found a loss of 0.5 year/centimetre of increased height (1.2 yr/inch). But these findings do not mean that all tall people die young. Many live to advanced ages and some become centenarians.
   An auxological approach that emphasizes multiple influences from all aspects of life, with special attention paid to prenatal and very early child development, seem to offer the most robust and accurate portrayal of overall growth and development. From these perspectives, we can better understand if the correlation persists, especially within developing countries prone to environmental uncertainties.
   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. 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.
   Adult height between populations often differs significantly. For example, the average height of women from the Czech Republic is greater than that of men from Malawi. This may be caused by genetic differences, childhood lifestyle differences (nutrition, sleep patterns, physical labor), or both.
  
  Depending on sex, genetic and environmental factors, shrinkage of stature may begin in middle age in some individuals but tends to be universal in the extremely aged. This decrease in height is due to such factors as decreased height of inter-vertebral discs because of desiccation, atrophy of soft tissues and postural changes secondary to degenerative disease.
   Most intra-population variance of height is genetic. Short stature and tall stature are usually not a health concern. If the degree of deviation from normal is significant, hereditary short stature is known as familial short stature and tall stature is known as familial tall stature. Confirmation that exceptional height is normal for a respective person can be ascertained from comparing stature of family members and analyzing growth trends for abrupt changes, among others. There are, however, various diseases and disorders that cause growth abnormalities.
   Increases in human stature are a main indicator of improvements in the average health of populations. The newest data set for the average height of adult male birth cohorts, from the mid-nineteenth century to 1980, in 15 European countries was studied (in the populations listed).
  
  During a century average height increased by 11 cm representing a dramatic improvement of this phenomenon. The apparent acceleration of body height occurred during the Ĝ.
  
  In the mid-nineteenth century young European women's menarche occurred at the average age of 16.5 years. One hundred years later, this age was reduced to under 12 years.
   It has been observed that first-born males are shorter than later-born males.
  
  However, more recently the reverse observation was made. The study authors suggest that the cause may be socio-economic in nature.
  
  Section::::Determinants of growth and height.:Nature versus nurture.
   The study of height is known as auxology. 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.
   The development of human height can serve as an indicator of two key welfare components, namely nutritional quality and health. 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. Some research indicates that a greater height correlates with greater success in dating and earning in men, although other research indicates that this does not apply to non-white men.
   Most notably, extreme height may be pathological, such as gigantism resulting from childhood hyperpituitarism, and dwarfism which has various causes. Rarely, no cause can be found for extreme height; very short persons may be termed as having idiopathic short stature. The United States Food and Drug Administration (FDA) in 2003 approved hGH treatment for those 2.25 standard deviations below the population mean (approximately the lowest 1.2% of the population). An even rarer occurrence, or at least less used term and recognized "problem", is idiopathic tall stature.
   The tallest living man is Sultan Kösen of Turkey, at . The tallest man in modern history was Robert Pershing Wadlow (1918–1940), from Illinois, United States, who was at the time of his death. The tallest woman in medical history was Zeng Jinlian of Hunan, China, who stood when she died at the age of seventeen. The shortest adult human on record was Chandra Bahadur Dangi of Nepal at .
   Human height
  
  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, usually in centimetres when using the metric system, or feet and inches when using the imperial system.
  
  A particular genetic profile in men called Y haplotype I-M170 is correlated with height. Ecological data shows that as the frequency of this genetic profile increases in the population, the average male height in a country also increases.
   Working on data of Indonesia, the study by Baten, Stegl and van der Eng suggests a positive relationship of economic development and average height. In Indonesia, human height has decreased coincidentally with natural or political shocks. 
  
  Section::::Average height around the world.
  
  As with any statistical data, the accuracy of such data may be questionable for various reasons:
  
  BULLET::::- Some studies may allow subjects to self-report values. Generally speaking, self-reported height tends to be taller than its measured height, although the overestimation of height depends on the reporting subject's height, age, gender and region.
   Studies show that there is a correlation between small stature & a longer life expectancy. Individuals of small stature are also more likely to have lower blood pressure & 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. Short stature decreases the risk of venous insufficiency. 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. Cancer risk has also been found to grow with height.
   Section::::Role of an individual's height.:Height and occupational success.
   It is estimated that the worldwide average height for an adult human male is about , while the worldwide average height for adult human females is about . Shrinkage of stature may begin in middle age in some individuals, but tends to be typical in the extremely aged. Through history human populations have universally become taller, probably as a consequence of better nutrition, healthcare, and living conditions. The average mass of an adult human is for females and for males. Like many other conditions, body weight and body type is influenced by both genetic susceptibility and environment and varies greatly among individuals. (see obesity)
   BULLET::::- Test subjects may have been invited instead of chosen at random, resulting in sampling bias.
  
  BULLET::::- Some countries may have significant height gaps between different regions. For instance, one survey shows there is gap between the tallest state and the shortest state in Germany. Under such circumstances, the mean height may not represent the total population unless sample subjects are appropriately taken from all regions with using weighted average of the different regional groups.
   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, 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. 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 relatively longer legs, averaging longer than the Guatemalan Maya (a significantly lower sitting height ratio).
  