Selasa, 17 Januari 2012

Economic and technological development and their relationships to body size and productivity

Robert W. Fogel and Lorens A. Helmchen, The growth in material wealth has been matched by changes in body size over the past 300 years, especially during the twentieth century. Perhaps the most remarkable secular trend has been the reduction in mortality. Between 1900 and 1998, life expectancy at birth in the United States increased by 65% for women, from 48.3 years to 79.5 years, and by 60% for men, from 46.3 years to 73.8 years (National Center for Health Statistics, 2001). Table 2.1 provides an overview of the long-term trend in life expectancy at birth for seven nations. The data show that in England life expectancy has more than doubled since the early eighteenth century. France has recorded even larger gains in longevity. French children born today can expect to live nearly three times longer than their ancestors 250 years ago.
Table 2.1
Life expectancy at birth (years) in seven nations, 1725–1990 (both sexes combined)
Country 1725 1750 1800 1850 1900 1950 1990
England or UK 32 37 36 40 48 69 76
France 26 33 42 46 67 77
US 50 51 56 43 47 68 76
Egypt 42 60
India 27 39 59
China 41 70
Japan 61 79
Source: Fogel (in press).
Table 2.2
Estimated average final heights (cm) of men who reached maturity between 1750 and
1875 in six European populations, by quarter centuries
Date of maturity by Great Britain Nor way Sweden France Denmark Hungary
century and quarter
18-III 165.9 163.9 168.1 168.7
18-IV 167.9 166.7 163.0 165.7 165.8
19-I 168.0 166.7 164.3 165.4 163.9
19-II 171.6 168.0 165.2 166.8 164.2
19-III 169.3 168.6 169.5 165.6 165.3
20-III 175.0 178.3 177.6 172.0 176.0 170.9
Source: Author’s calculations.
Although not as significant numerically, final heights of European men who reached maturity have also been increasing over the past two centuries, as shown in Table 2.2. In some countries, average heights increased by as much as 10 cm per century. Body weight has also increased. Figure 2.1 shows that for some age groups, the body mass index (BMI), a measure of weight adjusted for height (equal to kg/m increased by about 10–15% within the past 100 years. This chapter aims to elucidate the long-run relationship between labor productivity and body size. In particular, it will be shown that improvements in the nutritional status of a number of societies in Western Europe since the early eighteenth century may have initiated a virtuous circle of technophysio evolution. The theory of technophysio evolution posits the existence of a synergism between technological and physiological improvements that has produced a form of human evolution that is biological but not genetic, rapid, culturally transmitted, and not necessarily stable over time. In the con-text of the present study, we suggest that an increase in agricultural efficiency and labor productivity improved human physiology, in turn leading to further gains in labor productivity. The next two sections identify how the early modern advances in agriculture and the increased availability of calories per capita raised labor productivity over the course of successive generations. This is followed by an analysis of the determinants and consequences of accelerating productivity gains in American agriculture after World War II to illustrate the changing relationship among nutrition, body size, and labor productivity.
Energy cost accounting
Nutritional status is most commonly measured by the amount of calories available per person balanced against caloric requirements, also referred to as net nutrition
The principal component of the total energy requirement is represented by the basal metabolic rate (BMR). The BMR, which varies with age, sex, and body size is the amount of energy required to maintain body temperature and to sustain the functioning of the heart, liver, brain, and other organs. For adult males aged 20–39 years living in moderate climates, BMR normally ranges between 1350 and 2000 kcal/day depending on height and weight. For comparison across time and different populations, it is convenient to standardize for the age and sex distribution of a population by converting the per capita consumption of calories into consumption per equivalent adult male aged 20–39, also referred to as a consuming unit. Since the BMR does not allow for the energy required to eat and digest food, or for essential hygiene, an individual cannot survive on the calories needed for basal metabolism. The energy required for these additional essential activities over a period of 24 hours is estimated at 0.27 of BMR or 0.4 of BMR during waking hours. In other words, a survival diet is 1.27 BMR, or between 1720 and 2540 kcal/day for a consuming unit. A maintenance diet contains no allowance for the energy required to earn a living, prepare food, or any other activities beyond those connected with eating and essential hygiene.
Whatever calories are available beyond those claimed for basal metabolism and maintenance can be used at the discretion of the individual, either for work or for leisure activities.
Chronic malnutrition in late-eighteenth century Europe
According to recent estimates, the average caloric consumption in France on the eve of the French Revolution was about 2290 kcal per consuming unit, that for England was about 2700 kcal per consuming unit. These averages, however, do not reveal the variation in caloric consumption within the French and English populations. Table 2.3 shows the probable French and English distributions of the daily consumption of kcal per consuming unit toward the end of the eighteenth century. The principal finding that emerges from this table is the exceedingly low level of food production, especially in France, at the start of the Industrial Revolution. The French distribution of calories implies that 2.48% of the population had caloric consumption below basal metabolism, whereas the proportion of the English population below basal metabolism was 0.66%. For the remainder of the population, the level of work capacity permitted by the food supply was very low, even after allowing for the reduced requirements for maintenance because of small stature and reduced body mass. In France the bottom 10% of the labor force lacked the energy for regular work and the next 10% had enough energy for less than 3 hours of light work daily (0.52 hours of heavy work).
Although the English situation was somewhat better, the bottom 3% of its labor force lacked the energy for any work, while the balance of the bottom 20% had enough energy for only about 6 hours of light work (1.09 hours of heavy work) each day. Thus, at the end of the eighteenth century, the lack of access to sufficient calories effectively restricted the amount of activity (whether for income or leisure) that most laborers could perform, and it effectively precluded others from working at all.

Table 2.3
A comparison of the probable French and English distributions of the daily caloric
consumption (kcal) per consuming unit toward the end of the eighteenth century
Decile France c. 1785  England c. 1790
X 2290 (s/X) 0.3 X 2700 (s/X) 0.3
Daily kcal Cumulative % Daily kcal Cumulative %
consumption consumption
1. Highest 3672 100 4329 100
2. Ninth 2981 84 3514 84
3. Eighth 2676 71 3155 71
4. Seventh 2457 59 2897 59
5. Sixth 2276 48 2684 48
6. Fifth 2114 38 2492 38
7. Fourth 1958 29 2309 29
8. Third 1798 21 2120 21
9. Second 1614 13 1903 13
10. First 1310 6 1545 6
Sources and procedures: Author’s calculations.
Table 2.4
Secular trends in the daily caloric supply in France and Great Britain 1700–1989
(kcal per capita)
Year France Great Britain
1700                                                                                                 2095
1705 1657
1750                                                                                                 2168
1785 1848
1800                                                                                                 2237
1803–12 1846
1845–54 2480
1850                                                                                                 2362
1909–13                                                                                           2857
1935–39 2975
1954–55 2783 3231
1961                                                                                                 3170
1965 3355 3304
1989 3465 3149
Source: Fogel et al. (in press).


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