some causes of death—a poisoned arrow, a septic wound, or a ruptured organ or artery—leave no trace on the victim’s bones.
Once researchers have tallied a raw count of violent deaths, they can convert it to a rate in either of two ways. The first is to calculate the percentage of all deaths that are caused by violence. This rate is an answer to the question, “What are the chances that a person died at the hands of another person rather than passing away of natural causes?” The graph in figure 2–2 presents this statistic for three samples of nonstate people—skeletons from prehistoric sites, hunter-gatherers, and hunter-horticulturalists—and for a variety of state societies. Let’s walk through it.
The topmost cluster shows the rate of violent death for skeletons dug out of archaeological sites.48 They are the remains of hunter-gatherers and hunter-horticulturalists from Asia, Africa, Europe, and the Americas and date from 14,000 BCE to 1770 CE, in every case well before the emergence of state societies or the first sustained contact with them. The death rates range from 0 to 60 percent, with an average of 15 percent.
FIGURE 2–2. Percentage of deaths in warfare in nonstate and state societies Sources: Prehistoric archaeological sites: Bowles, 2009; Keeley, 1996. Hunter-gatherers: Bowles, 2009. Hunter-horticulturalists and other tribal groups: Gat, 2006; Keeley, 1996. Ancient Mexico: Keeley, 1996. World, 20th-century wars & genocides (includes man-made famines): White, 2011. Europe, 1900–60: Keeley, 1996, from Wright, 1942, 1942/1964, 1942/ 1965; see note 52. Europe, 17th-century: Keeley, 1996. Europe and United States, 20th century: Keeley, 1996, from Harris, 1975. World, 20th-century battle deaths: Lacina & Gleditsch, 2005; Sarkees, 2000; see note 54. United States, 2005 war deaths: see text and note 57. World, 2005 battle deaths: see text and note 58.
Next are figures from eight contemporary or recent societies that make their living primarily from hunting and gathering.49 They come from the Americas, the Philippines, and Australia. The average of the rates of death by warfare is within a whisker of the average estimated from the bones: 14 percent, with a range from 4 percent to 30 percent.
In the next cluster I’ve lumped pre-state societies that engage in some mixture of hunting, gathering, and horticulture. All are from New Guinea or the Amazon rain forest, except Europe’s last tribal society, the Montenegrins, whose rate of violent death is close to the average for the group as a whole, 24.5 percent.50
Finally we get to some figures for states.51 The earliest are from the cities and empires of pre-Columbian Mexico, in which 5 percent of the dead were killed by other people. That was undoubtedly a dangerous place, but it was a third to a fifth as violent as an average pre-state society. When it comes to modern states, we are faced with hundreds of political units, dozens of centuries, and many subcategories of violence to choose from (wars, homicides, genocides, and so on), so there is no single “correct” estimate. But we can make the comparison as fair as possible by choosing the most violent countries and centuries, together with some estimates of violence in the world today. As we shall see in chapter 5, the two most violent centuries in the past half millennium of European history were the 17th, with its bloody Wars of Religion, and the 20th, with its two world wars. The historian Quincy Wright has estimated the rate of death in the wars of the 17th century at 2 percent, and the rate of death in war for the first half of the 20th at 3 percent.52 If one were to include the last four decades of the 20th century, the percentage would be even lower. One estimate, which includes American war deaths as well, comes in at less than 1 percent.53
Recently the study of war has been made more precise by the release of two quantitative datasets, which I will explain in chapter 5. They conservatively list about 40 million battle deaths during the 20th century.54(“Battle deaths” refer to soldiers and civilians who were directly killed in combat.) If we consider that a bit more than 6 billion people died during the 20th century, and put aside some demographic subtleties, we may estimate that around 0.7 percent of the world’s population died in battles during that century.55Even if we tripled or quadrupled the estimate to include indirect deaths from war-caused famine and disease, it would barely narrow the gap between state and nonstate societies. What if we added the deaths from genocides, purges, and other