Thoughts on “The Book of War: The Evolutionary Biology of Racism, Religious Hatred, Nationalism, Terrorism, and Genocide” by Daniel Kriegman

by Gabor Por · November 6, 2025

Do you believe humans are inherently benevolent or malevolent? And why do you believe one way or another? Does it even matter what you believe? It probably matters to you as you view the world and humans through your own specific lens, including your belief system. What if instead of believing, you had proof for a more science-based approach to that question, or at least to a subset of the issues springing from the answer? The ethical question of what constitutes good or evil is too generic. Let’s narrow the topic to how it is possible for people to commit acts that most of us, but not all, would consider immoral. The subtitle of Kriegman’s book–“Racism, Religious Hatred, Nationalism, Terrorism, and Genocide”– lists some of these and even gives a hint of the answer: “Evolutionary Biology.” It is not so much about the how, though, but the why. Spoiler: The central thesis of his book, the human capacity for mass violence is “deeply human” rather than inhuman and is the direct result of humans evolving from great apes who naturally organize into competitive groups using coordinated violence, with larger brains enabling the formation of extended identity groups based on religious and ideological beliefs.

There are plenty of deeply human stories in the book, which is the layer I enjoyed the most. The authors’ personal memories, observations about humanity in general, and the myriad examples of violence. These I could relate to, evoked emotion and intellectual responses in me, and I highly recommend them on a personal level. The intellectual honesty he approaches the difficult question of holocausts (yes, in plural), is truly admirable. Another level is the scientific explanations and exploration of evolutionary biology and how it explains our capacity for violence. While some of the details were fascinating, I admit that I sometimes had a harder time following them.

At this point, I need to mention the style of the book, because it was in the top ten most difficult I have ever read. I was a graduate student 15 years ago in another discipline, so I am only somewhat used to this level of academic writing. The style was sometimes rather obtuse for my feeble mind, and the long compound sentences required some heavy mental disentanglement. I recognize that the whole text is a rich tapestry of rhetorical, philosophical, and scientific exposition, blending historical reflection, speculative fiction, evolutionary psychology, and even political commentary. Part of the fun and challenge is to follow where the author takes you in any given paragraph. He employs a multidisciplinary voice that shifts between the eloquent skepticism, imaginative detachment of science fiction, and the analytical rigor of contemporary social science. The tone is often critical and reflective, using irony and juxtaposition to underscore the paradoxes of belief and conflict. The prose is dense and layered, with frequent use of historical references, academic citations, and illustrative anecdotes.

For me, a topic of interest in the book was religion as its perennial student. Kriegman had a lot to say about it, its relation to war, and it all boiled down to this: religion is not the root cause of war, but rather a culturally evolved tool that amplifies innate human tendencies toward group-based aggression. It is a provocative, intellectually charged argument that challenges conventional narratives by synthesizing evolutionary theory, political history, and cognitive science. Was I convinced of the claim’s validity? Mostly. More importantly, he gave me a lot to think about. I need to keep going back to check the details. By now, his conclusion feels reasonable, but I also want to fully understand it.

As someone who studies sociology too, another main claim from the book was much easier for me to accept: religious ideologies function like hammers—they are instruments developed for specific purposes (tribal warfare success) rather than root causes of conflict. In my version of sociology, everything is a process and/or a social construct. So the analogy of a hammer related by groups makes total sense to me. As a matter of fact, this approach explains a lot of why war happens and how religion plays a role in it.

I want to thank the author for challenging me to read 670 pages of dense text and illustrations, excluding the 90 pages of the appendix. It was the kind of mental exercise I have not done since graduate school. But it was worth it. I felt my cerebral muscles working overtime. Just as with physical exercise, I not only got mentally stronger but also gained a lot from it. The plethora of ideas, connections, and topics I could explore now based on the references from this book, is amazing. I also believe I now have a deeper understanding of war, even if I internalized only a minuscule portion of the author’s thinking.

The author’s website and Wikipedia page.

Disclaimer: I have received a digital copy of this book and a small amount from the author, which did not affect my review in any way.

Year first published: 2023