The world is growing up. While today's humans may not be any wiser than their forebears, they are much taller: in the past 150 years the average height of Europeans, for example, has climbed more than 20 cm. And according to the emerging science of auxology, the study of human growth, becoming taller means a whole lot more than seeing better at football matches or being able to paint the bathroom ceiling without a ladder.
The evidence of auxologists--who cross the disciplines of economic history, pediatrics, biology and sociology--is that average height reflects how well, or badly a population is doing--its diet, wealth, quality of housing, levels of pollution, disease and stress--and is a far better measure of a nation's standard of living than such conventional indicators as gross national product or per capita income. Their findings have important implications for government policymakers, manufacturers, urban planners and designers, and indicate that the world around us, from airplanes to bathtubs, is going to have to change its scale. Among the questions auxology raises: Is there an ideal height? Is there a limit to how tall humans can grow? Can shorter populations catch up?
There is no suggestion that big is beautiful or better or that smart Davids won't continue to outdo lumbering Goliaths. And the scientists would distance their research on height from any notions of national pride or ethnic prejudice. Auxologists accept that height is a response to both nature and nurture. Their argument is that genetic differences aside, changes in living conditions cause dramatic changes in average height. The better those conditions, the taller the average citizen. Says Richard Steckel, a professor and an economic historian at Ohio State University who has been studying height since 1975: "Although genes are important determinants of individual height, studies of genetically similar and dissimilar populations under various conditions suggest that differences in average height across most populations are largely attributable to environmental factors."
If height is used as the only criterion, the best place in the world to grow up today is probably the Netherlands. Young Dutchmen average 183 cm, or just above 6 ft., and the average height of all Dutchmen is 179 cm, about a centimeter taller than Norwegians, Danes and Swedes. American males and Englishmen average 175 cm. More than a century ago, Steckel says, the Dutch were among the shortest people in Europe, and back in 1750 the average American stood 7 cm above the average Englishman. Adds Steckel: "Perhaps Americans' loss of international leadership in stature should be a warning to those who think this country provides its citizens with widespread access to the basic necessities of life."
Height is a remarkable reflection of this access, or lack of it. Instead of revealing outputs, such as goods produced or wages earned, it explains inputs: positive ones such as food and warmth, and also negative ones like overcrowding and illness. Says Steckel: "while weight is an indicator of a person's current state of health, height reflects an individual's history of net nutrition, meaning what is left for growth after the first demands made by maintenance, work, activity, disease, et cetera."
Roderick Floud, an economic historian who is also provost of London Guildhall University, describes height as "an extremely sensitive measurement" and asks of the conventional economist's gauge of well-being, "What does a national wage average really mean, given there is such great inequality of income?"
Researchers stress that they are talking averages, not individuals, but they have established clear links between height and health. In Norway a survey by professor Hans Waaler showed that tall men and women live significantly longer: of women ages 40 to 44, for example, those standing between 145 cm and 149 cm had a mortality rate double that of' women 165 cm to 169 cm tall. Norwegian men ages 55 to 59 who stood 150 cm to 155 cm had a mortality rate twice that of men whose height was 185 cm to 189 cm.
There is a strong negative association between adult height and the risk of dying from heart disease. Auxologists who cross-checked height and health records among more than 4,000 soldiers called up to fight for the Union Army in the American Civil War found that short men were far more likely than tall men to be rejected because of bad teeth, hernias or circulator, disease.
Such studies do not conclude that being tall is in itself a positive benefit. In old-fashioned warfare being big probably meant being a better target. Neither is longevity a simple consequence of increased stature. What the studies show is tallness as a product of good living conditions in a society, meaning good general health, and therefore bodies that on average are likely to resist time's ravages for a longer span of time.
On the individual level tallness has obvious pluses and minuses in day-to-day living. Low door frames and cramped airplane seating are clear disadvantages for the lofty. Says Phil Heinricy, who runs the Tall Persons Club of Great Britain and Ireland, and whose height is 203 cm, or 6 ft. 8 in.: "You could make a longer list of disadvantages than advantages. I remember one short plane flight where I couldn't get the space next to the emergency exit, and when I got off I could barely walk." But Heinricy says he would not change his height were he able to. "Or I'd go up, not down. In a room full of people I never have to worry about starting a conversation."
Humans experience the bulk of their vertical growth in two spurts: during early childhood and adolescence. The latter surge is typically about two years earlier in girls than in boys, which is why the lads are temporarily shorter. Men eventually, stand above women because their second growth period lasts about two years longer.
What auxologists call "environmental insults" can slow or stop this growth. Obvious "insults" are poor nutrition, illness, lack of hygiene, polluted surroundings and overcrowded housing. But height also reflects far more subtle influences. For example, Floud says there is evidence that boys at Britain's private boarding schools grow more in the holidays than in term time, "presumably because they are happier."
Floud says love, or rather lack of it, can manifest itself in stature. He cites an infamous child-abuse case in Britain. Says Floud: "When little Maria Colwell was with her parents, she stopped growing and her weight went down. When she was taken by authorities and put in hospital, she started to catch up. Returned to her home, she again stopped growing." It was Maria's death in 1973--when she was seven years old and weighed only 16 kilos--that led to reforms of child-protection laws in England. "Today," says Floud "when pediatricians suspect abuse, the first thing they do is take height measurements over a period." There is a converse proof of the importance of stature, says Floud, whose wife is a social worker. "If you take a child from a children's home and put it with foster or adoptive parents, the first thing you have to do is provide money for new clothes because the child suddenly grows. You can't doubt the relationship."
Another expression of height as a social litmus test is a study of nearly 10,000 5-to-11-year-old English and Scottish children that found a clear connection between a child's height and whether the father had a job. The study ranked the socioeconomic status of the families and found "in each social-class group, children with unemployed fathers were shorter." In one group the average difference was 4 cm. Floud says the message is clear: "Lower incomes produce lower heights."
Auxologists have shown that children of European, African, Middle Eastern and Indian descent grow much the same way, given the same conditions. While there does appear to be a genetic factor causing Far Eastern races, such as the Japanese, to remain shorter under the same good circumstances, they too are shooting up compared with their forebears. Between 1957 and 1977, the average heights of 12- and 13-year-old Japanese rose nearly 10 cm.
Strange as it may sound, the Japanese, like the rest of the world, are growing not up but down. It was, appropriately, a Dutchman who made this discovery. In 1778 Johannes Martinet, a vicar who studied the growth of 12 Amsterdam boys over a six-year period, observed, "Thou seest this astonishing fact, that the body has not grown mainly upwards, but mostly downwards." What he meant was that the legs produce most of our increased growth. Says a modern Dutch authority, professor Hans van Wieringen, a social pediatrician from Utrecht: "There is strong evidence that the ... shift in adult height is chiefly a shift in leg length." One of the pioneers of height studies, English pediatrician James Tanner, author of the book Foetus into Man, found that the 10-cm surge in Japanese children between 1957 and '77 was "purely of leg length."
What environmental factors have given the Dutch and Scandinavians ever longer legs and steadily reduced the relative height advantage of Americans? There are three answers to the first question. Says Floud: "First, they're rich. They have very high income levels. Second, they are very healthy; they spend a lot of money on antenatal care; they have extremely low infant-mortality rates. Children are basically very well cared for. Third, they have, certainly by comparison with the U.S. and increasingly with Britain, very equal distributions of wealth. America has substantial inequality of income, so the upper classes are tall and strong, but there is a very long tail behind them, and that pulls the average down."
In which case, where do all those gigantic black American athletes spring from, given that they don't typically have cushy backgrounds? Richard Steckel suggests that black tallness is partly an illusion caused by "visibility," the fact that basketball players have a big audience. Says he: "There is evidence that blacks have longer arms and legs than whites, but if you look at the whole black population, you find more really tall people but also more really, short people compared with the white population."
It is too early to be sure why average American heights began to level off after World War II, but one factor may be those "insults" caused by what economic historians call "urban disamenities," which include substandard, overcrowded city housing, inadequate health care and stress. Another cause may be poorer diet than in past eras because of increasing consumption of processed foods, plus "overnutrition," or abusive eating. The reasons why Americans held a height advantage in the first place would seem to support urban disamenities as one factor. Says Steckel: "Possible causes for Americans reaching near modern heights as early as the mid 1700s, while Europeans lagged more than a century behind, were a good diet, infrequent epidemics associated with low population density and widespread access to land and other resources." Steckel suspects that apart from crowded city life, "there are pockets of poverty in America where biological needs are not being met."
The reduction in the height gap between Americans and Europeans can be explained in part by the blurring of class differences in Europe, where, unlike in America, they have been deeply rooted. John Komlos, an economic historian at Munich University, studied height records kept by a school for boys in Stuttgart in the second half of the eighteenth century, and found that 14-year-old lower-class boys were 14.2 cm, or nearly a head, shorter than boys of the same age from the upper levels of the aristocracy. "Those class differences have largely gone in much of Western Europe," says Komlos. "In 1981 German boys aged 14 averaged 161.2 cm, or exactly 20 cm more than those lower-class Stuttgart boys." Female growth, says Komlos, has been equally startling: "Bavarian women born in the 1850s averaged 155 cm as adults; in 1981 girls reached that height at 12 1/2!
An even greater class-height gap was discovered by Floud when he began his research in the late 1970s. Says Floud: "I came across the records of an association called the Marine Society a charity which from 1756 took boys--and some girls, although they measured only the boys--from the slums of London and found them berths as servants on merchant and navy ships. You could compare this information with the records of the Royal Military Academy at Sandhurst, which at that stage was taking teenagers from the upper and upper-middle classes and fitting them to become officers. There are some points in that period where the upper-class children are 18 cm to 20 cm taller than the slum children of the same age. The adage that the upper classes could look down on the working classes was literally true."
While America has typically been more egalitarian, there have been periods in which distribution of increasing overall wealth became distinctly uneven. Says Steckel: "Scholars have suggested growing inequality in America between 1830 and 1890 might have offset the rise in per capita income and account for a small drop in average stature. The heights of upper-classmen- -students at Amherst and Yale universities--rose from 171 cm to 173 cm in that period, while those of the Ohio National Guard declined by several centimeters."
Other studies have confirmed that heights do not rise continuously, that there are national slumps in growth. In Australia, for example, sometimes called the Lucky Country for its abundance of land and natural resources, average height slipped 3 cm between 1867 and 1893. Melbourne economic historians Stephen Nicholas and Greg Whitwell point out that the drop cannot be easily attributed to the bad working conditions that came with industrialization in Europe. More probable was the rapid shift from rural to urban life, bringing increased vulnerability to diseases such as typhoid, plus economic hardships caused by a depression in the 1890s.
Because nature abhors such "insults" to growth, it offers second chances. Once an inhibitor is removed--for example, an undernourished child begins to be well fed--some of the lost growth can be recovered. And deprivation in the adolescent spurt leads to extension of the normal growth period by as much as several years, into the early 20s. Says Floud: "That 18th century height gap between the Marine Society's intake and the Sandhurst intake probably reduced to between 7 cm and 10 cm when these youngsters reached adulthood."
If the insult is severe enough and lasts long enough, stunted growth is inevitable, but the catch-up effect can be seen even in the records of American slaves. Income was hardly a useful measure of a slave's quality of life, but traders recorded height and other physical information. Says Steckel: "Slave children were dreadfully small, shorter than 999 out of 1,000 modern American children. But typically there was a remarkable catch-up spurt in their teenage years, perhaps because slaves needed to be fed well as they approached the age where they could be put to work."
Height has played such an important role in human history that even the dead have tall tales to tell. Steckel is part of a large team of anthropologists and other specialists examining thousands of skeletal remains from earlier societies in North and South America. Because growth changes are largely "downward," measuring the long leg bone, the femur, gives a very accurate guide to how tall a person was. Says Steckel: "Worldwide, the percentage of human height that comes from the femur is very similar across nations: between 25.5% and 27.8%." Steckel says height calculations from femurs indicate that "there were some very healthy populations in America 4,000 or 5,000 years ago."
Apart from better knowledge of our ancestors, what does auxology tell us about our future? Says Dutch social pediatrician Hans van Wieringen: "Clothing, furniture and tools have to be redesigned, and the architecture of houses, schools, offices and workshops has to be adapted."
In Holland, the new land of the tall, this is happening. Says Van Wieringen: "Industrial designers are now taking average height into account, and the carmakers were very interested in our height surveys. In schools already desks are being made in accordance with the change in stature."
Other countries are also realizing the need for adjustments. The London Daily Telegraph reported this month that the navigator of a Royal Air Force Tornado aircraft got his head jammed against the cockpit canopy when he turned to observe another airplane during a mock dogfight. He freed himself with difficulty. The report said neither his helmet nor his seat adjustment caused the problem: he was just too tall for his surroundings. The newspaper added that most R.A.F. pilots today "would not be able to fit behind the joystick" in older fighters like the Spitfire or the Hurricane.
If average height and well-being go hand in hand, there is some consolation for the Portuguese, who had the lowest average height among conscripts from 11 European countries surveyed by researchers from Denmark. Although the tallest recruits, the Dutch, were 10.5 cm taller than the Portuguese, the Danish scientists found indications that the Portuguese will catch up. They noted a direct connection between postnatal mortality (deaths between 28 days and one year) and average height. Once improved conditions bring this mortality rate down near 3 deaths per thousand, the height of 18-year-olds tends to level off at 179 cm to 181 cm. While Sweden reached this 3-to-1,000 mortality, rate in 1964, that level was achieved in Spain, for example, only in 1986. The Danish auxologists speculate that "adult height in middle and southern European countries will continue to increase for about two decades after postnatal mortality has reached a low and stable level at 3 to 5 per 1,000 deliveries." Meaning by the year 2006, the average Spaniard may be rubbing shoulders with the average Swede.
Where will it all end? If Dutch girls of 13 and boys of 14 are now typically 25 cm taller than their counterparts 150 years ago, will some singer of the future be crooning, "Ten foot two, eyes of blue ... ?" Says Holland's' Van Wieringen: "I doubt it, but that's just my belief. If you say human spines couldn't cope with such height, well, giraffes and other animals manage to combine enormous height and weight. Maybe our skeletal power would increase at the same time. I don't think our upper height limit has been reached."
There are indications that there may be limits to the height-health connection. The Norwegian study found that lower mortality rates for tall people level off at around 188 cm, or 6 ft. 2 in. The rate stays much the same to 193 cm (6 ft. 4 in.), then starts to climb for the really tall. Similarly, in the survey of Union Army recruits in America, the incidence of chronic ailments declines with height up to 188 cm, then starts to rise again. A University of Bristol auxologist, Dr. David Gunnell, says that despite these surveys, most studies show no clear upper limit in the height-mortality relationship. But tallness does have its medical drawbacks. Says Gunnell: "Generally, taller people have an increased risk of cancer."
Researchers don't like sticking their necks out on eventual or optimum heights, although Floud did mention with a smile that the latter might be about 6 ft. 2 in., which he happens to be. More seriously, Floud agrees with another British authority and social historian, Bernard Harris of Southampton University, that auxology's findings are good news. Harris told a congress on gerontology in Manchester in July: "The association between height and mortality suggests more people are entering old age with lives that are less damaged by the insults and depredations suffered by earlier generations. So more people can look forward not only to living longer but also to living healthier lives."
While their science is relatively new, auxologists are convinced about the need for far more height measurement of children and adolescents, both as standard health practice in developed countries and as a cheap and effective way to tell how aid programs are working in developing nations. The auxologists' message might be: Spare the ruler and spoil the child.
Relative mortality risk among men ages 40 to 59
Height Mortality Risk 142 cm 2.5* 147 2.4 157 1.7 163 1.5 168 1.3 172 1.0 178 .95 182 .8 188 .75 193 .7 197 1.0
*1.0 represents average risk; 2 represents twice the average risk; .5 is half that risk and so on. Source H.T. Waaler