Had twentieth-century wars killed the proportion typical of tribal warfare, there would have been about two billion deaths rather than 100 million.

Judged as of 2007. Test the arithmetic against estimates published by 2007: the typical share of a tribal population killed in war (often cited as roughly 15% or more, for example Keeley, or tribal annual war-death rates applied to 20th-century populations) and roughly 100 million 20th-century war deaths. True: those estimates imply about two billion counterfactual deaths, within roughly 1.5 to 3 billion, alongside about 100 million actual deaths (roughly 70 to 180 million). Mostly true: the implied figure is the same order of magnitude but somewhat outside that band (about 1 to 4 billion), or the actual figure is somewhat off. Mixed: the method or numbers are contested enough that the result could plausibly fall well below or above that. Mostly false: the underlying estimates are real but the conversion overstates the contrast several-fold, or the tribal figures came from unrepresentative samples, which critics such as Fry and Ferguson argue. False: correct use of the cited estimates gives a figure nowhere near two billion (for example, well under 500 million).

Set before the research began.

1. E1 Selected Death Tolls for Wars, Massacres and Atrocities Before the 20th Century necrometrics.com (Matthew White's death-toll compilation) · 20 December 1998

   “Combining these into a sample group of 22 gives us a median of about 15.1%.”

2. E2 In Defence of the Reviled 20th century Peace Research Institute Oslo (PRIO) · 30 December 2015

   “Together these events are estimated to have cost 100–115 million human lives.”

3. E3 In Defence of the Reviled 20th century Peace Research Institute Oslo (PRIO) · 30 December 2015

   “The best indicators are statistics for the world population, which increased from 1.7 billion in 1900 to 6 billion in 2000.”

4. E4 The prehistory of violence and war: Moving beyond the Hobbes–Rousseau quagmire Journal of Peace Research (Oxford Academic) · 1 July 2023

   “Pinker’s (2011: 49) famous figures – drawn from Bowles’ (2009) nomadic HG sample and analysis – which purported to reveal that prehistoric warfare was highly lethal, were recently rebutted by Fry & Söderberg’s (2013a) larger and ostensibly more accurate sample.”

5. E5 Selected Death Tolls for Wars, Massacres and Atrocities Before the 20th Century necrometrics.com · 20 December 1998

   “In practical terms, this means that for every 1,000,000 people who lived outside of a literate state, some 120,000 to 160,000 would eventually be killed in war.”

6. E6 Selected Death Tolls for Wars, Massacres and Atrocities Before the 20th Century necrometrics.com · 20 December 1998

   “Combining these into a sample group of 22 gives us a median of about 15.1%.”

7. E7 The prehistory of violence and war: Moving beyond the Hobbes–Rousseau quagmire Journal of Peace Research (Oxford Academic) · 1 July 2023

   “which somewhat reduces the percentage death from 14% to 9% (Fry, 2013; for other points of contention see Fry & Söderberg, 2014).”

8. E8 Selected Death Tolls for Wars, Massacres and Atrocities Before the 20th Century necrometrics.com · 20 December 1998

   “my calculation is that for every million people who lived in the 20th Century, some 37,000 died by violence.”

9. E9 Armed Combat and Warfare Human Relations Area Files (Yale University), Ember, Berke and Zhang · 14 October 2026

   “Keeley (1996, 90), summarizing mortality from 8 ethnographic populations and 7 archaeological populations, describes the percentage of deaths for adults from war to range between 7.5-43%; for male deaths the range is between 8% and 58%.”

10. E10 Armed Combat and Warfare Human Relations Area Files (Yale University), Ember, Berke and Zhang · 14 October 2026

    “Bowles (2009), summarizing war mortality in 15 archaeological populations and 8 ethnographic populations, calculates an average of 14% war mortality for adults with a high of 46%.”

11. E11 Armed Combat and Warfare Human Relations Area Files (Yale University), Ember, Berke and Zhang · 14 October 2026

    “The work of Fry (2007) excludes feuding and it leads him to conclude that nomadic hunter-gatherers are generally peaceful and to lack warfare.”

12. E12 Armed Combat and Warfare Human Relations Area Files (Yale University), Ember, Berke and Zhang · 14 October 2026

    “Regardless of these findings, this argument has been criticized on the basis of methodology, sample, and study design (summarized in Basava 2022; Gat 2012; Turchin 2015).”

The evidence supports a tribal war-death share of about 15% (E1, E5) and about 100–115 million deaths from unnamed events (E2). However, no item works out the counterfactual 20th-century toll. The only rate comparison uses 37,000 violent deaths per million (E8), a broader measure that cannot be compared directly with tribal war deaths. Most of the contestation evidence (E4, E7, E12) also postdates 2007. So the evidence does not settle whether the conversion's result is contested enough to be "mixed" under the criteria.