Human height

Human height, or stature, is the height of a human being. Adult height generally varies little between people compared to other anthropometric measures. Exceptional height (variation from the average of around 20%) is usually due to gigantism or dwarfism. Adult height for one sex in a particular ethnic group follows more or less a Gaussian distribution (bell curve) but with some individuals lying several standard deviations away from the mean. (The tallest well-documented giant was 8 foot 11 inches (2.72 m) tall.) Height is determined by the interaction of genes and environment. Final adult height may be attained anywhere from the early teens to early 20s, though it is most commonly reached during the mid teens for females and late teens for males. A person's height also varies over the course of the day, by an average of 19 mm (¾ in), gradually shrinking as the spine compresses over the course of a day, and stretching back out overnight (Tyrrell, et al. 1985).

Changes in human height

Human height is regulated by many factors. Since the development of modern medicine and plentiful nutrient-rich food in the developed world average height has increased dramatically. Nutrition is the most important factor in determining height; and height records from military records and other documents can be used to quite accurately compare nutrition and height in various eras. Evidence has shown that height decreased in Britain in the early nineteenth century, before beginning its long increase around mid-century. Increase in height has not been constant; however. The European Middle Ages was an era of tallness with men of above six feet (1.83 m) considered unremarkable. In Europe human height reached its nadir at the start of the nineteenth century. Until the general rise in human health, as urbanization increased, the accompanying trend was a height decline.

Europeans in North America were far taller than those in Europe in the eighteenth and nineteenth centuries, in fact the tallest in the world. The original indigenous population was also among the tallest populations of the world at the time. However, several nations, indeed many nations in Europe, have now surpassed the US in terms of average stature, particularly the Netherlands and Scandinavian nations. Most markedly is the Netherlands where average height has increased at the greatest rates. For instance: the Netherlands was in the late nineteenth century a land renowned for its short population, but today it has the tallest average in the world with young men averaging 1.83 m tall. The Dutch are now well known in Europe for extreme tallness. The increase has been so dramatic that various things have been redesigned to fit the much taller frames. In contrast, average male height in impoverished Vietnam and North KoreaThe Seattle Times: "Short stature evident in North Korean generation" (free registration required) remains comparatively small at 5 ft 4 in (1.63 m) and 5 ft 5 in (1.65 m) respectively. Currently, young North Korean males are actually significantly shorter. This contrasts greatly with the extreme growth occurring in surrounding Asian populations with correlated increasing standards of living. Young South Koreans are about 3 inches (8 cm) taller than their North Korean counterparts, on average. The difference between South Koreans, and even older North Koreans, compared to young North Koreans who grew up during the famine of the 1990s-2000s is extraordinary.

Determinants of growth and height

The study of human growth is known as auxology. Growth and height have long been recognized as a measure of the health and wellness 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 populations. Average height is increasingly used as a measure 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 is 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 1950s. Severe malnutrition is known to cause stunted growth in North Korean, portions of African, certain historical European, and other populations. Diet (in addition to needed nutrients; such things as junk food and attendant health problems such as obesity), exercise, fitness, pollution exposure, sleep patterns, climate (see Allen's rule and Bergmann's Rule for example), and even happiness (psychological well-being) are other factors that can affect growth and final height.

Height is determined by the complex interactive combination of genetics and environment. Genetic potential plus nutrition minus stressors is a basic formula. Humans grow fastest (other than in the womb) as infants and toddlers (birth to roughly age 2) and then during the pubertal growth spurt. A slower steady growth velocity occurs throughout childhood between these periods; and some slow, steady, declining growth after the pubertal growth spurt levels off is common. These are also critical periods where stressors such as malnutrition (or even severe child neglect) have the greatest effect. Conversely, if conditions are optimal then growth potential is maximized; and also there is catch-up growth -- which can be significant -- for those experiencing poor conditions when those conditions improve.

Moreover, the health of a mother throughout her life, especially during her critical periods, and of course during 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 an accumulative generation effect such that nutrition and health over generations influences the height of descendants to varying degrees.

The precise relationship between genetics and environment and exact role of genetics itself is complex and uncertain. Human height is both of moderately high phenotypic plasticity and is highly heritable. Height is a multigenic trait. There are substantial relationships in the heights among biological families; the heights of parents and family are a good predictor for the height of their children. Environmental influences are most pronounced if they are highly favorable or unfavorable to growth, especially when occurring during critical periods and when continuing multigenerationally. Genetic profile (genotype) provides potentialities or proclivities which interact with environmental factors throughout the period of growth resulting (phenotype) in final adult height. Essentially, the developing body devotes energy to growth after other bodily functions are satisfied.

Asian populations were once thought to be inherently shorter, but with the increases in height in East Asian nations such as Japan and South Korea as diet changes, it now seems that humans as a species probably possess a roughly similar genetic height potential (excluding permutations like the Pygmies), and that thus a predictive genotypic basis for height differentiation has not yet evolved.

Process of growth

Growth in stature, determined by its various factors, results from the lengthening of bones via cellular divisions chiefly regulated by somatotropin (human growth hormone (hGH)) secreted by the anterior pituitary gland. Somatotropin also stimulates the release of another growth inducing hormone insulin-like growth factor 1 (IGF-1) mainly by the liver. Both hormones operate on most tissues of the body, have many other functions, and continue to be secreted throughout life; with peak levels coinciding with peak growth velocity, and gradually subsiding with age after adolescence. The bulk of secretion occurs in bursts (especially for adolescents) with the largest during sleep. Exercise promotes secretion; however, too much work or anaerobic and muscular development can impede growth or even induce premature cessation, or can induce premature closing of the growth plates (indeed, adolescents who take steroids can experience stunted growth). A positive net nutrition is also important, with proteins and various other nutrients especially important.

The majority of linear growth occurs as growth of cartilage at the epiphysis (ends) of the long bones which gradually ossify to form hard bone. The legs compose approximately half of adult human height, and is a somewhat sexually dimorphic trait. Height is also attained from growth of the spine, and contrary to popular belief, men are the "leggier" gender with a longer leg to torso ratio, conversely to women's longer torso to leg ratio. (The illusion of the proportion being the other way around is caused by fatty deposits placed high on women's hips). Some of this growth occurs after the growth spurt of the long bones has ceased or slowed. The majority of growth during growth spurts is of the long bones. Additionally, the variation in height between populations and across time is largely due to changes in leg length. The remainder of height consists of the cranium. Height is obviously sexually dimorphic and statistically it is more or less normally distributed, but with heavy tails.

Height abnormalities

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. Most notably, extreme height may be pathological, such as gigantism (very rare) 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 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.

Role of an individual's height

For men, shortness is often a disadvantage with other men being less likely to respect short men and women generally finding them less attractive. Women in most cultures tend to prefer tall men as partners. It is especially important to them (and also to most men) that the man be taller than the woman. Taller politicians have a tendency to win elections. Studies have found taller men marry earlier and earn higher wages. Others have found that most CEOs and upper management individuals are taller than average. (However, some studies suggest that it is not adult height but rather the usually correlated height during adolescence that is the determinative factor, suggesting that it is the impact of height on self-image that is operative. Yet other studies have found no significant difference in self-image and social status for shorter adolescent boys.) It is almost the opposite for women where tallness may be seen as unattractive to some men. Still, it is not uncommon to see 6 ft (1.83 m) tall female supermodels, where the field has other imperatives than real-life sexual attraction. Discrimination based on height is known as heightism.

Tallness is correlated to better cardio-vascular health and overall better than average health and longevity. However height may not be causative of better health and longevity.McCarron et al. Respond to "Height-Cardiovascular Disease Relation": Are All Risk Factors Equal?, Peter McCarron, Mona Okasha, James McEwen and George Davey Smith, American Journal of Epidemiology, Vol. 155, No. 8 : pp. 690-691, 2002. On the other hand being too tall can cause awkward situations in society and not being able to fit into society. http://news.bbc.co.uk/1/hi/england/4227752.stm

The physics of human height

torque = rotational inertia X angular acceleration. Rotational inertia = sum of the mass of the products of the mass of each particle by the square of its distance from the axis of rotation. These equations mean that the shorter human can accelerate more quickly than the taller human. The taller human requires considerably more torque to gets its body moving. This also means that the taller human can generate considerably more torque. For similar reasons the shorter human can decelerate more quickly and change directions more quickly than the taller human. This gives the shorter human more agility and quickness than the taller human.

These equations of rotational dynamics also show that the shorter human is prone to be more coordinated than the taller human. When the taller human sets himself in motion his body gains more angular momentum than the shorter human and it requires considerably more torque for the taller human to control his body. The shorter human will tend to be more coordinated than the taller human.

When the taller human starts to lose his balance, again his body will gain more angular momentum which will require more torque to control. The shorter human will tend to have better balance than the taller human.

These effects can easily be understood if one tries to control a 12 inch (30 cm) ruler as opposed to a yardstick (1 m ruler). The shorter ruler will be much easier to accelerate, decelerate, change directions, control and balance, although the yardstick can generate more power.

In many sports such as baseball, the greater torques that the taller players can generate give them almost an overwhelming advantage over the shorter player. In other sports such as basketball, the greater reach of the taller players is an overwhelming advantage. In American football the taller bodies can carry much more mass than the shorter bodies and this gives the taller body an advantage. However, in the case of running backs in American football the shorter players are able to use the advantages of greater acceleration, agility, coordination and balance to compete successfully against the more massive taller players. Many running backs enshrined in the Pro Football Hall of Fame measure 5 feet 10 inches (178cm) or less, significantly shorter than elite players at other positions.

Acceleration, agility, coordination and balance are at a great premium in indoor soccer and we find a large number of players in this sport of short stature. There is also a great abundance of players of short stature in outdoor soccer(International football).

The role of height in sports

Height often plays a crucial role in sports. For most sports, height is useful as it affects the leverage between muscle volume and bones towards greater speed of movement. It is most valuable in sports like basketball and volleyball, where the "short" players are well above average in height compared to the general population. In some sports, such as horse racing, auto racing, and gymnastics, a smaller frame is more valuable.

In other sports, the role of height is specific to particular positions. For example, in soccer, a tall goalkeeper is at an advantage because he has a greater armspan and can more easily jump higher, so one will rarely, if ever, see a short goalkeeper in professional soccer. In rugby union, lineout jumpers are usually the tallest players on the pitch, as this increases their chance of winning clean ball, whereas scrum-halves are usually relatively short. In American football, a tall quarterback is at an advantage because it is easier for him to see over the heads of large offensive and defensive linemen while he is in the pocket on a pass play. Tall wide receivers are at an advantage because they can out jump shorter defensive backs to catch high balls. By contrast, shorter running backs are often thought to be at an advantage because they can get "lost" behind large offensive linemen, making it harder for defenders to react at the beginning of a play. Thus, in the NFL and in NCAA Division I football, running backs under 6 ft 0 in (1.83 m) are more common than running backs over 6 ft 3 in (1.91 m). Former Heisman Trophy winner and NFL All-Pro Barry Sanders, thought by some to be the greatest running back in history, is a classic example of a running back with an extraordinarily low center of gravity. However, Jim Brown, usually considered the greatest running back of all time, was more than 6 ft 2 in (1.88 m) tall, helping display the benefits conferred by the greater leverage which height provides.

Average adult height around the world

	Metric system		Imperial system
Country	Males	Females	Males	Females	Age range sampled	Source
Australia	178.4 cm	163.9 cm	5 ft 10.2 in	5 ft 4.5 in	18-24 (measured)	g
Australia	179.9 cm	164.9 cm	5 ft 10.8 in	5 ft 4.9 in	18-24 (self reported)	g
Canada	180.0 cm	164.9 cm	5 ft 10.9 in	5 ft 5.0 in	18-24 (self reported)	j
China	169.7 cm	158.6 cm	5 ft 6.8 in	5 ft 2.4 in	Adult population	v
Denmark	180.3 cm	165.2 cm	5 ft 10.9 in	5 ft 5.0 in	18-24 (measured)	u
Dinaric Alps	185.6 cm	171 cm	6 ft 1 in	5 ft 7.3 in	17	q
France	173.1 cm	161.8 cm	5 ft 8.2 in	5 ft 3.7 in		a
France	175.6 cm	162.5 cm	5 ft 9.2 in	5 ft 4.0 in		n
Finland	176.6 cm	163.5 cm	5 ft 9.5 in	5 ft 4.3 in		a
Finland	178.2 cm	164.7 cm	5 ft 10.1 in	5 ft 4.7 in	15-64 (self reported)	p
Germany	174.5 cm	163.5 cm	5 ft 8.7 in	5 ft 4.4 in		c
Germany	180.2 cm	169.0 cm	5 ft 10.9 in	5 ft 6.5 in		e
Hongkong	164.0 cm	155.0 cm	5 ft 4.5 in	5 ft 1 in		t
Italy	174.58 cm	166.2 cm	5 ft 8.7 in	5 ft 5.4 in	Athletes	s
Japan	165.6 cm	153.0 cm	5 ft 5.2 in	5 ft 0.2 in		c
Japan	171.1 cm	157.5 cm	5 ft 7.3 in	5 ft 2.2 in	18	m
Korea, South	173.3 cm	160.9 cm	5 ft 8.2 in	5 ft 3.3 in	18	m
Lithuania	181.2 cm	167.5	5 ft 11.3 in	5 ft 6.0 in	Adult population	r
Netherlands	178.7 cm	167.1 cm	5 ft 10.3 in	5 ft 5.7 in		a
Netherlands	181.8 cm	170.1 cm	5 ft 11.6 in	5 ft 7 in	secondary school students	d
Netherlands	184.0 cm	170.6 cm	6 ft 0.4 in	5 ft 7.2in	21	h
New Zealand	177.0 cm	165.0 cm	5 ft 9.7 in	5 ft 5 in	19-45	k
Norway	179.8 cm	167.6 cm	5 ft 10.8 in	5 ft 5.9 in	18-19?	f/x?
Spain	170.0 cm	160.3 cm	5 ft 6.9 in	5 ft 3.1 in		a
Spain	169.0 cm	158.3 cm	5 ft 7 in	5 ft 2.9 in	45-69 (self reported)	o
Spain	173.0 cm	161 cm	5 ft 8.2 in	5 ft 3.in	entire population (self reported)	o
Spain	177.0 cm	164.3 cm	5 ft 10 in	5 ft 4.6 in	18-29 (self reported)	o
Sweden	177.9 cm	164.6 cm	5 ft 10 in	5 ft 4.6 in		a
Sweden	180.1 cm	167 cm	5 ft 10.9 in	5 ft 5.7 in	16-24	l
Switzerland	175.4 cm	164.0 cm	5 ft 9 in	5 ft 3.8 in		a
Taiwan	171.62 cm	159.46 cm	5 ft 7.5 in	5 ft 2.75 in	18	2003
UK	175.0 cm	161.4 cm	5 ft 9 in	5 ft 3.5 in	Entire population	x
UK	177.2 cm	163.0 cm	5 ft 9.5 in	5 ft 4 in	16-24	x
USA	175.5 cm	162.6 cm	5 ft 9 in	5 ft 3.3 in		c
USA	176.2 cm	162.5 cm	5 ft 9.4 in	5 ft 4 in	20-74	i
USA	178.2 cm	164.1 cm	5 ft 10.2 in	5 ft 4.6 in	20-39 non-Hispanic whites	i
USA	177.8 cm	164.0 cm	5 ft 10 in	5 ft 4.6 in	20-39 non-Hispanic blacks	i
USA	169.7 cm	158.1 cm	5 ft 6.8 in	5 ft 2.3 in	20-39 Mexican Americans	i

Sources:

a = Cavelaars et al 2000*

b = kurabe.net**

c = 'Fitting the Task to the Man'

d = Netherlands Central Bureau for Statistics, 2000

e = Eurostats Statistical Yearbook 2004

f = Statistics Norway 2002

g = ABS How Australians Measure Up 1995 data

h = Leiden University Medical Centre 1997

i = Mean Body Weight, Height, and Body Mass Index 1960-2002

j = Progress in Prevention 1995***

k = Size and Shape of New Zealanders: NZ Norms for Anthropometric Data 1993****

l = Statistics Sweden 2000

m = Official Statistics by Ministry of Health, Labour and Welfare^*

n = UFIH (French Union of Clothing Industries) 2006

o = Sigma Dos Statistics 2003

p = National Public Health Institute(Finland)^*

q = Dynamique de l'evolution humaine 2005

r = Department of Anatomy, Histology and Anthropology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania

s = ISTAT, 1980 Birth Cohorts. Females: Average statures of athletes.

t = Woo J, et al. Population bone mineral density measurements for Chinese women and men in Hong Kong. Osteoporos Int 2001; 12:289-295.

u = Committee for determining the eligibility of young men for military service.

v = National statistics, 2001 (website in Chinese)

x = Health Survey for England 2004^*

Notes:

a* Based on self reported and not measured height

b** Some values from this site have been disputed, see the Human height for more information.

j*** Based on self reported and not measured height

k**** Based on British norms and their relations to New Zealand values

References

Fitting the Task to the Man, 1987 (for heights in USA and Japan)
Eurostats Statistical Yearbook 2004 (for heights in Germany)
Netherlands Central Bureau for Statistics, 1996 (for average heights)
Mean Body Weight, Height, and body mass index, United States 1960 - 2002
How Australians Measure Up
UK Department of Health - Health Survey for England
Statistics Norway, Conscripts, by height, Per cent
Statistics Sweden (in Swedish)
Burkhard Bilger. "The Height Gap." The New Yorker
A collection of data on human height, referred to here as "karube" but originally collected from other sources, was originally available here but is no longer. A copy is available here. (an English translation of this Japanese page would make it easier to evaluate the quality of the data...).
http://www.cdc.gov/nchs/pressroom/04news/americans.htm
Cavelaars,A.E.J.M.,Kunst,A.E.,Geurts,J.J.M.,Crialesi,R.,Grotvedt,L.,Helmert U. Persistent variations in average height between countries and between socio-economic groups: an overview of 10 European countries. Annals of Human Biology. 27(4),407 - 421.
Tyrrell, A.R., Reilly, T., Troup, J.D., 1983. Circadian variation in stature and the effect of spinal loading. Spine 10, 161--164.
Average height of adolescents in the Dinaric Alps

Notes

External links

CDC National Center for Health Statistics: Growth Charts of American Percentiles

For a more accurate worldwide statistical study data covering males and females from 1 - 18 years of age, check this link (scroll down to table III - IV).