What may explain the change in comparative growth rate? Bilger turns to J.W. Drukker, a professor of economic history at the University of Groningen, who analyzed databases of Dutch soldiers and their incomes. Drukker found that
Holland’s growth spurt began only in the mid-eighteen-hundreds…, when its first liberal democracy was established. Before 1850, the country grew rich off its colonies, but the wealth stayed in the hands of the wealthy, and the average citizen shrank. After 1850, heights and income suddenly fell into lockstep: when incomes went up, heights went up (after a predictable lag time), and always to the same degree.
The average height of native-born American males has not significantly changed since the middle of the twentieth century. This plateau contrasts with the trends in Europe, where growth increases have continued, dramatically in countries like the Netherlands, which now has on average the tallest European men. Factors that have been considered by way of explanation of static American growth are social inequality, an inferior health care system, and fewer welfare safety nets compared to western and northern Europe, despite our high per capita income. Although our health care system and its long-standing lack of universal coverage is often blamed as a primary factor, we should not jump to this conclusion.
For example, infant mortality rates in 2005, which some consider to be indicators of the success or failure of a nation’s health care system, were 2.4 deaths per 1,000 births in Sweden and 6.8 deaths per 1,000 births in the US.11 This would seem to support the difference between universal coverage in Sweden and millions of uninsured in the US. But in Canada, which has long had a national single-payer system, the infant mortality rate was 5.3 deaths per 1,000 births, more than twice that in Sweden. Social and cultural factors beyond universal health care coverage clearly are relevant to rates of infant mortality.
According to some economic historians, the widening gap between rich and poor in the United States may have caused the growth curve to have flattened and even reversed. One contributing factor may be the American fast-food diet that is causing many to grow horizontally rather than vertically. Fogel and his coauthors write:
Today, overnutrition and obesity are concerns. Inequalities in death, chronic disorders, activity limitation, body size, and access to better nutritional and medical services are still observed among various socioeconomic groups. Thus, eliminating this new type of malnutrition and reducing these inequalities are the American challenges for the twenty-first century.
In fact, the distribution of fast foods that are cheap, filling, and associated with obesity is not uniform. The Centers for Disease Control and Prevention in 2009 noted that “blacks had a 51 percent higher prevalence of obesity and Hispanics had a 21 percent higher obesity prevalence compared with whites.”
In January 2010, the Centers for Disease Control and Prevention published an analysis of the most recent changes in weight, as well as in height, in the United States from the National Health and Nutrition Examination Survey (NHANES).12 The prevalence of obesity in adults, defined as a body-mass index of 30 or greater, was relatively stable over the period of 1960 to 1980. The BMI then jumped, and currently the prevalence of obesity is 32.2 percent among adult men and 35.5 percent among adult women. But obesity does not appear to be increasing at a uniform rate: the prevalence of a high BMI appeared to reach a plateau between 1999 and 2006, except among the most obese.
Floud, Fogel, Harris, and Hong question how meaningful these recent changes in height and weight may be for standard of living, longevity, and productivity. They rightly caution against overinterpreting the fact that Americans, and more recently certain groups in Europe and in Asia,13 have an increasing average BMI. A few decades of data may not be enough to mark a lasting change in “technophysio evolution.”
Early in The Changing Body, the authors state that “there are dangers, but also benefits, in simplification and the use of analogy.” At one point, they write that the nutritional status and the amount of work of one generation “determines” the welfare of the next. But quickly they pull back:
It might perhaps be prudent to replace the word “determines”…by the word “influences” or “partially determines.” …The schema is certainly not put forward as a deterministic model; there are, in its workings, many historical contingencies and also many uncertainties.
That their model has such limits will likely become more apparent as we have access to a century of data from comprehensive surveys like those conducted by the CDC that don’t depend on stitching together historical documents. The authors also consider whether new variables, like climate change, might affect their model. Despite these concerns, the authors place themselves on the side of the “Whig interpretation of history, one of continual progress toward a better society.” That view certainly applied to the experience of my family and others with immigrant roots: America proved to be a place of robust growth in every sense of the phrase. But in view of our often reckless treatment of the environment and ourselves, the question raised at the conclusion of The Changing Body, whether these improvements will continue, is aptly answered by the authors: “We do not know.”
11 The Organisation for Economic Co-operation and Development (OECD), Health at a Glance, 2007; see also T.R. Reid, The Healing of America (Penguin, 2009), pp. 33–34. ↩
12 Katherine M. Flegal et al., "Prevalence and Trends in Obesity Among US Adults, 1999–2008," Journal of American Medical Association ( JAMA ), January 13, 2010. See also J. Michael Gaziano, "Fifth Phase of the Epidemiologic Transition: The Age of Obesity and Inactivity," JAMA, January 13, 2010; and Cynthia L. Ogden et al., "Prevalence of High Body Mass Index in US Children and Adolescents, 2007–2008," JAMA, January 13, 2010. ↩
13 Wei Zheng et al., "Association Between Body-Mass Index and Risk of Death in More Than 1 Million Asians," New England Journal of Medicine ( NEJM ), February 24, 2011. See also Alpana P. Shukla et al., "Body-Mass Index and Risk of Death in Asians," NEJM, June 2, 2011. ↩
The Organisation for Economic Co-operation and Development (OECD), Health at a Glance, 2007; see also T.R. Reid, The Healing of America (Penguin, 2009), pp. 33–34. ↩
Katherine M. Flegal et al., “Prevalence and Trends in Obesity Among US Adults, 1999–2008,” Journal of American Medical Association ( JAMA ), January 13, 2010. See also J. Michael Gaziano, “Fifth Phase of the Epidemiologic Transition: The Age of Obesity and Inactivity,” JAMA, January 13, 2010; and Cynthia L. Ogden et al., “Prevalence of High Body Mass Index in US Children and Adolescents, 2007–2008,” JAMA, January 13, 2010. ↩
Wei Zheng et al., “Association Between Body-Mass Index and Risk of Death in More Than 1 Million Asians,” New England Journal of Medicine ( NEJM ), February 24, 2011. See also Alpana P. Shukla et al., “Body-Mass Index and Risk of Death in Asians,” NEJM, June 2, 2011. ↩