Book Reviews

Michael Tomasello, A Natural History of Human Morality, Harvard University Press, 2016

The dust jacket to A Natural History of Human Morality advertises “the most detailed account to date of the evolution of human moral psychology.” Reading this description, you might expect a hefty, multi-volume work filled with mitochondrial maps, genotype to fitness landscapes, and appendix after appendix of experimental results. Thankfully, you will find none of these things within this slim, breezy, 163-page monograph. What you will find could be better described as an “introduction” or an “outline” to an ongoing research program, which may very well become the “the most detailed account…of the evolution of human moral psychology” that we can hope for. But the greatest virtue of A Natural History of Human Morality, to my mind, is its merciful lack of detail. Tucked between its narrow covers is a simple yet engaging story about the emergence of a new kind of cooperation among upright apes, which we call “morality.”

With its welcomed brevity and immanent readability, this book can be enjoyed by just about anyone. However, it will probably appeal most to readers who have neither the time nor the background to keep up with the many articles that Michael Tomasello publishes every year, but who want to find out what all the hubbub is about. If you’ve never read a book on the evolution of morality before, there’s no better place to begin. For those of you who have kept up with Tomasello’s work over the years, you’ll find little that you don’t already know, but you will walk away with a clearer understanding of what he’s up to and where his project is headed.

What is the book about? In Tomasello’s own words, the “goal of the current account is to provide an explanation, an evolutionary explanation, for how the human species transformed great ape strategic cooperation into genuine human morality” (147). More specifically, Tomasello identifies a number of moral psychological capacities that are unique to humans, and then defends an empirical hypothesis about how and why these capacities evolved in our genus (and only in our genus).

The story begins with the great apes, or, more precisely, with the most recent common ancestors of humans and great apes. These apes, like their non-human descendants, were built for competition. They exhibited a kind of “Machiavellian intelligence,” implementing flexible strategies and even predicting the mental states of conspecifics, if for no other reason than to outsmart them (22). However, these early apes were also able to form long-term partnerships, since the scales of competition could be tipped in one’s favor by enlisting the help of some close friends, whether for a fight or a monkey hunt. Thus, we find in these ancestral apes a number of proto-moral psychological capacities, organized around feelings of sympathy toward kin and collaboration partners. They could be moved by the plight of others, and could even inhibit self-interested impulses for the sake of maintaining social cohesion. According to Tomasello, these apes and all their descendants, including humans, are capable of a primitive “Morality of Sympathy,” defined by the aforementioned moral psychological capacities.

Fast forward five million years or so to early humans. These hominids still followed the Morality of Sympathy, but they had acquired new moral psychological capacities, which enabled them to follow the more complex “Morality of Fairness.” Collaboration had become more common, and to collaborate more easily and effectively, early humans developed the capacities to engage in joint attention and to form joint commitments (76). They placed an intrinsic value on working together with others, and so were less likely to renege on partnerships, even if reneging would bring greater rewards. Furthermore, they developed an abstract conception of what a collaboration partner ought to be and do, leading them to select partners carefully, to reward good partners, and to punish bad partners through expressions of second personal agency. Whereas great apes allow collaboration partners to enjoy small portions of a food prize, but keep the lion’s share for themselves, early humans were intent on distributing food prizes equally, or as they saw it, fairly (76).

Fast forward again a few hundred thousand years to modern humans. Today, we are moved not only by sympathy and fairness, but also by a sense of justice. The basic moral psychological capacities that enabled early humans to form joint commitments with collaboration partners have generalized, enabling us now to form collective commitments with members of our cultural milieu (92). We maintain social identities, constituted by a unique way of doing things and a unique pool of background knowledge that allows us to quickly and effortlessly collaborate with other, even unknown members of our cultures. This “Morality of Justice,” as Tomasello calls it, involves the observance and enforcement of social norms that transcend particular partnerships, applying to everyone in a community.

To summarize, Tomasello argues that the individual intentionality of the great apes (governed by the Morality of Sympathy) developed into the joint intentionality of early humans (governed by the Morality of Fairness), which, in turn, developed into the collective intentionality of modern humans (governed by the Morality of Justice). Through these stages, “the human species transformed great ape strategic cooperation into genuine human morality” (147). The most interesting part of the story, however, deals with why these new moral psychological capacities developed in the way that they did. Two key transitions allowed for individual intentionality to develop into joint intentionality, and then for joint intentionality to develop into collective intentionality.

The first significant event was an ecological change in Africa that forced early humans into obligate collaborative food collection practices. Early humans could not compete with apes and monkeys in collecting fruit from trees or nuts from shrubs, and so to survive, they needed to work together to hunt large game or to guard foraging locations from other hungry species. Because food collection required everyone’s participation—such that one person slacking off would prevent everyone from eating—collaboration became an absolute necessity rather than a strategic gambit. Early humans thus became interdependent in a way that no other ape had been before. Because each person needed help from her friends to survive, and because her friends needed help from her too, everyone benefited from joint undertakings. Obligate collaboration thus paved the way to joint intentionality.

The second significant event was the growth of culture. Once tribes grew large enough that members could not possibly know everyone else in their tribe, and once tribes came into conflict with one another over resources, the need to identify and work together with unknown members of one’s own tribe became more pressing. Unique dialects, dress, and cultural practices emerged as means of distinguishing “us” from “them.” Furthermore, the assumption of common cultural knowledge between members of a tribe allowed people to collaborate with strangers without explicit communication or planning. With the creation of a cultural identity, humans formed ideas of how people should be and act in general, and not just how temporary collaboration partners should be and act. On Tomasello’s picture, then, justice is fairness writ large—joint intentionality that has generalized into collective intentionality with the emergence of culture.

What did I like about the book? The single best thing about this book, to my mind, is that it demonstrates how fruitful collaborations between philosophy and empirical science can be. When Tomasello writes about particular moral psychological capacities, he waxes philosophically like the best of us. (I was especially delighted to find that, on page 83, Tomasello’s three citations are to Stephen Darwall, Peter Strawson, and Alexander Kojeve. Some pages later, Tomasello cites Hegel’s Phenomenology of Spirit to support a claim about mutual recognition. And the final citation in the book is to Nietzsche). Yet when writing about the phylogenetic and ontogenetic development of these capacities, he relies entirely on empirical findings, many of which were produced in his lab. The ease with which Tomasello moves from armchair to Bunsen burner is an impressive feat to witness, and a model for others to emulate.

Related to this point, Tomasello has a knack for writing excellent summaries. He seems to be well aware of this strength, as much of the book—which is itself a summary of his recent work—is dedicated to summarizing various elements of his view. Don’t want to read the whole book? You’ll find summaries of the overarching thesis on pages 1-8, 136-137, and 143-146. You’ll even find graphical representations of it on pages 148 and 153. Want to skip over chapter 2, which discusses the great ape Morality of Sympathy? Tomasello summarizes the key moves on pages 35 and 143-144. Summaries of chapters 3 and 4, which discuss the early human Morality of Fairness and the modern human Morality of Justice, respectively, can be found on pages 41, 75, 76-77, and 144-145 (for chapter 3), and pages 86-87, 109, 120-121, and 145-146 (chapter 4). By the time you reach the conclusion, you’ll be able to recite Tomasello’s three categories of moral psychological capacities (cognitive, social-interactive, and self-regulatory), three systems of morality (sympathy, fairness, and justice), and two transformative changes (the rise of obligate collaboration and the rise of culture) by heart. I can imagine that unusually sharp or especially knowledgeable readers will tire of the repetitive summaries, but I, for one, found them immensely helpful in keeping track of the overarching story.

What did I not like about the book? In case it’s not already clear, I like this book a great deal. Indeed, I would strongly recommend it to anyone with at least a passing interest in moral psychology. That being said, the book does suffer from a couple of weaknesses. First, Tomasello rarely addresses criticisms of his view. He often cites authors who are critical of his view—or who at least defend incompatible views of the evolution of human morality—without even mentioning that these authors are not on board with his hypothesis. This silence may leave many readers with the impression that Tomasello’s account enjoys unanimous support or is simply the only account in town. Readers who are unfamiliar with the literature might want to add Hrdy (2009), Boehm (2012), Greene (2013), and de Waal (2014) to their reading lists, just to see some of the other theories on offer. I’d love to see a second edition published with peer commentaries followed by Tomasello’s replies.

Relatedly, Tomasello concludes the book by attempting to situate his account within three related literatures, which he calls “evolutionary ethics” (he cites Alexander [1987], Sober and Wilson [1998], and de Waal [2006]), “moral psychology” (he cites Kohlberg [1981], Mikhail [2007], and Greene [2013]), and “gene-culture evolution” (he cites Shweder et al. [1987] and Prinz [2012]). Yet in place of a nuanced discussion of how his view is or is not consistent with these other approaches, we get only the vague pronouncement that “the current account has attempted to be more comprehensive” (142). I filled many margins with questions about how Tomasello’s account may or may not dovetail with those of Greene (2013) and de Waal (2014), for instance, and I was disappointed that Tomasello rarely offered clear answers to my questions. That being said, it seems to me that philosophers will be in a good position to work out the implications of Tomasello’s view, especially given the clarity with which the philosophical and empirical issues have been presented, and I am confident that this book will generate fruitful discussions for years to come.

Trip Glazer
Department of Philosophy
Georgetown University
Washington, DC, USA


Alexander, Richard D. 1987. The Biology of Moral Systems. New York: Aldine De Gruyter.

Boehm, Christopher. 2012. Moral Origins: The Evolution of Virtue, Altruism, and Shame. New York: Basic Books.

de Waal, Frans. 2006. Primates and philosophers: How morality evolved. Edited by Stephen Macedo, and Josiah Ober. Princeton: Princeton University Press.

de Waal, Frans. 2014. The Bonobo and the Atheist: In Search of Humanism Among the Primates. New York: W. W. Norton & Company.

Greene, Joshua. 2013. Moral tribes: Emotion, reason, and the gap between us and them. New York: Penguin.

Hrdy, Sarah Blaffer. 2009. Mothers and Others: The Evolutionary Origins of Mutual Understanding. Cambridge: Belknap Press.

Kohlberg, Lawrence. 1981. Essays on Moral Development, Vol. 1: The Philosophy of Moral Development. San Francisco: Harper and Row.

Mihail, John. 2007. “Universal Moral Grammar: Theory, Evidence and the Future.” Trends in Cognitive Sciences 11 (4): 143-152.

Prinz, Jesse. 2012. Beyond Human Nature. London: Allen Lane.

Shweder, Richard A., Manamohan Mahapatra, and Joan G. Miller. 1987. “Culture and moral development.” In The emergence of morality in young children, edited by Jerome Kagan, and Sharon Lamb. 1-83. Chicago: University of Chicago Press.

Sober, Elliott, and David Sloan Wilson. 1998. Unto Others: The Evolution and Psychology of Unselfish Behavior. Harvard: Harvard University Press.