Gender Difference

[Excerpt below is from Chapter 3 of War and Gender]

For information about this book, and a discussion forum, click below:
War and Gender: How Gender Shapes the War System
      and Vice Versa

Joshua S. Goldstein
(Cambridge University Press, September 2001)

Graph, NY Marathon times
Speed in NY Marathon by gender, 1997

Strength Strength is clearly more influenced by culture than is height. Most US 18-year-old boys have spent far more time than girls in rough-and-tumble play, vigorous sports, and other activities which use and stimulate the development of strength. Their female counterparts have had much less strength-promoting activity, and this was more true of the sample of US 18-year-olds measured in 1982 (see below) than it is today, thanks to girls’ sports.

Furthermore, different kinds of physical strength show different gender patterns. Women are constitutionally stronger than men – they live longer and are more resilient against fatigue, illness, famine, childbirth (!), and so forth. “Anyone who has observed women of Africa on lengthy treks carrying heavy loads of firewood and water cannot help seeing how arbitrary our indicators of strength are.”64

Data on strength are available from the US military – not an ideal sample, but similar to the general population in height. A 1982 report rates five areas of strength and gives male soldiers’ strength relative to females as follows: upper-body, 72 percent higher; leg extensor, 54 percent; trunk flexor, 47 percent; lean body mass, 33 percent; and aerobic capacity, 28 percent. Upper-body strength, the area of greatest gender difference, is emphasized in military training. Field exercises in which troops march sustained distances carrying heavy packs seem to be a key point at which men rate women as inferior. One West Point colonel said, “The women just drop.” On the other hand, sometimes women can use their bodies in different ways than men to achieve the same result.65

Lifting capacity shows the greatest gender disparity – probably in part because far more young men than women in US culture in 1982 engaged in weight training. The 1982 data indicate an average lifting capacity for women soldiers of 66 pounds, versus 119 for men (80 percent higher). The difference in lifting capacity is especially critical at around 100–120 pounds. An Air Force test for lifting 110 pounds was passed by 68 percent of men and 1 percent of women. I do not know how important lifting capacity is in the range of capabilities that enhance combat effectiveness, but it does resonate with the clincher line of the retired colonel’s argument quoted above (p. 159), that a weakling woman would be unable to save her wounded comrade’s life in battle by dragging him away. Thus, the 80 percent difference here seems far more likely than the 8 percent difference in height to explain why so few women participate in combat.66

Actually, however, the key question is not the difference in gender averages, but rather how much the bell-curves overlap. Figure 3.10 shows the data on lifting capability from the US military data. The curves indeed overlap less than for height, but not much less – still more than 10 percent of the military women have greater lifting capacity than the lowest 10 percent of men. Recall that these data are not biological givens but reflect the influence of a culture where men try to grow up big and strong, girls thin and pretty (back in 1982). Remember, too, that lifting capacity (part of upper-body strength) is the area of greatest gender difference among all the kinds of strength that go into combat (running, enduring fatigue, etc.). Thus, even the most pronounced gender differences regarding height and strength alike appear to show a nontrivial overlap of bell-curves, albeit nowhere near gender equality.

Figure 3.10 Lifting capacity by gender, US soldiers, 1982.

Speed and endurance In addition to being large and strong, combat soldiers travel long distances on foot, sometimes at high speed. This requires running speed and endurance. It is an especially significant capability because of claims that it was important in our evolutionary past. (Some scholars see the human body as especially adapted to running over open terrain, in the context of long-distance hunting on the African plains. This capability would thus be quite primordial in the evolution of war. Evidence on this question is disputed, however.)67

In speed, as in size or strength, men score above women on average but men’s and women’s bell-curves overlap. I calculated the curves for the 1997 New York Marathon, which had posted on the Internet the rank and time of each of 30,427 people to finish the race (nearly three-quarters of them male). Figure 3.11 shows average speed over the 26.2 mile race. As the figure shows, although the median woman ran 11 percent slower than the median man, the great majority of men finish well behind the fastest women, and the great majority of women finish well ahead of the slowest men. The sample represented here is not typical of the general population. The bulk of the curve represents the most motivated and skilled long-distance runners from the New York area – less than 1 percent of the population. The right-hand end of the curve is even less representative since many of the fastest runners in the world compete in the New York Marathon. For example, none of the first 13 finishers were Americans. They came from Kenya, Italy, Mexico, and other countries. Presumably this elite sample would exaggerate gender difference, representing as it does the tails of the two bell-curves.68

Figure 3.11 Speed in New York Marathon by gender, 1997.

Implications These data on overlapping curves imply that if armies included just the largest, strongest, fastest soldiers, then we should find many cases of women’s participation in combat, albeit in smaller numbers than for men. The actual gender composition of such an army would be determined by the extent to which a population was mobilized into the army. If being a warrior were an elite occupation practiced by a select few, say 5 or 10 percent of the population, then the best army might contain virtually all men. If, however, a society needed to induct half of the entire population into the army, it would score highest on size and strength by including something like 85 percent men and 15 percent women.69

Perhaps the virtually all-male armies found historically result from warfare’s being just an occupation of a small elite. This makes sense in that most people most of the time in the world are not at war, and in many wars only a minority of the population needs be mobilized as combat soldiers. In reality, however, the extent of mobilization of populations into warfare varies greatly from culture to culture and through time. These variations should be reflected, if Hypothesis 3C is correct (and given the data on overlapping bell-curves), in patterns of women’s participation in combat. We may frame this as a corollary to Hypothesis 3C – that is, a testable statement that should be true if the hypothesis is true: the participation of women in combat increases where mobilization for war is more extensive.

This corollary, however, receives very weak empirical support at best. True, in those few cases where nontrivial numbers of women participated in combat historically, extreme warfare forced extreme mobilization of a population (see pp. 60–70). However, these particular cases are a small minority of the cases in which societies centered around war or faced dire war crises. In the great majority of such cases, even when most of the male population lived by war most of the time, virtually no women participated in combat (see pp. 10–21). These cases include preindustrial warrior societies such as the Sambia of New Guinea and the Yanomamö of Brazil, as well as industrialized societies engaged in “total war” such as the World Wars. So the corollary would lead us to expect far more women in combat and far more fluctuation over time in numbers of women in combat than we actually find.70

The problems are compounded by a second corollary: the introduction of firearms to warfare, both locally and in a global-historic sense, should increase the participation of women in combat (by making size-strength differences less decisive). The problem is that this hardly ever happened. Furthermore, this point can be extended to all kinds of forms of industrialized warfare in which machines rather than human bodies alone provide size and strength – tank warfare, air combat, and so forth. The point is not that strength does not matter at all in these occupations, but rather that the introduction of such forms of warfare shifts the importance of body strength in combat forces relative to other combat skills of various kinds. Yet the historical mechanization of war produced little change in the gender ratio of combat forces over the past century – a problem for Hypothesis 3C.71

To consider an even more basic corollary: most wars should be won by the side with the larger, stronger soldiers. If size and strength are so critical to military effectiveness, they must frequently determine battle outcomes. But in fact this is not true. Military historians emphasize the importance of such factors as strategy, discipline, fighting spirit, accurate intelligence, and (especially) the quality of weaponry, in determining the outcome of battles – more than the importance of one side’s physical strength. Indeed, the one war that America has lost, Vietnam, was to an army whose members were substantially shorter and less strong than Americans.72

The evolutionary implications of this corollary also run into trouble, since size and strength apparently have not been “selected for” in humans. Compared with species closely related to humans, notably the other great apes, humans have a relatively small gender difference in size. Gorilla and orangutan adult males, for example, are typically almost twice as large as females. Larger size exacts an evolutionary cost, mainly in higher food requirements, which would be worth it only if size and strength mattered greatly in fighting. Apparently for humans they did not. Men were probably about 35 percent heavier than women several million years ago, but only about 15 percent larger starting before Neanderthals several hundred thousand years ago, remaining around 15 percent heavier in modern humans. Furthermore, modern humans totally displaced the substantially stronger and larger Neanderthals about 30,000 years ago.73

Finally, if gender differences in size underlay gender differences in participation in war, then we should find among primates that species with large gender differences in body weight should also have low female participation in intergroup fighting. In fact, however, across 21 primate species, these two variables are uncorrelated.74

Overall, then, the data on size and strength give limited support at best to Hypothesis 3C. The major problem is that in the context of overlapping bell-curves, the considerable variations across time and space – in mobilization of a population for war, in size and strength, and in the importance of size and strength to war – do not produce the variations predicted by Hypothesis 3C in terms of gender composition of war-fighting forces.

64 Peterson and Runyan 1993, 35.

65 US Army 1982, 2.15; Wrangham and Peterson 1996, 181; Francke 1997, drop 248; Lorber 1994, result 53.

66 US Army 1982, 2.15; Presidential Commission 1993, passed C-74.

67 M. Harris 1989, 195.

68 cf. Snyder 1998.

69 M. Harris 1989, 278–84, 195; Harris 1974, 77; Harris 1977, 63–64; Casey 1991, 17; Astrachan 1986, 61.

70 Ambrose 1997, 321; Moon 1998, 91.

71 M. Harris 1989, 285; Ehrenreich 1997a, 229.

72 Harris 1974, 84; Dyer 1985, 124; Mead 1949, 133.

73 Hall 1985, 134–39; Wilford 1997b; Suplee 1997; Wrangham and Peterson 1996 175, 178; Wilson 1978, 126–28.

74 Manson and Wrangham 1991, 373.

To book website:
War and Gender: How Gender Shapes the War System
      and Vice Versa

Joshua S. Goldstein
(Cambridge University Press, September 2001)