Frans de Waal’s new book on human morality presents its very own ethical quandary. Namely, can you fault a work such as The Bonobo and the Atheist: In Search of Humanism Among the Primates for failing to satisfactorily address moral philosophy’s most pressing questions? It is, after all, a rare book that passes this test (some might argue one has yet to be written.)

No, The Bonobo and the Atheist is better thought of as a collection of musings from a prominent scientist than as a rigorous treatment of the nature of morality. As such, it gets a pass on many of the more intractable issues of its subject matter.

De Waal, an Emory University primatologist, has spent his career uncovering the surprising social behaviors of various primate species like chimpanzees, rhesus monkeys, and—perhaps most famously—those peacemaking, enthusiastic fornicators known as bonobos. In his more-than-a-dozen books, he has thoughtfully mined the goings-on of the ape world for insights about the human one.

In The Bonobo and the Atheist, de Waal intends to refute—or at least breezily cast doubt upon—the idea of morality as a “thin veneer over a cauldron of nasty tendencies.” The raw materials for ethics, he argues, have been present in the natural world since before humanity. In his effort to argue against the notion that “human beings don’t know how to behave and that someone must tell us,” he takes issue with sources of “top-down” moral authority, whether religion, reason, or some “white-coated priesthood” of scientists. Morality, in other words, “is not as much of a human invention as we like to think.” It’s a view de Waal has advanced before, most notably in his previous book Primates and Philosophers: How Morality Evolved.

Not surprisingly, de Waal’s chief articles of evidence for his view are the moral emotions and empathic, sometimes altruistic behaviors exhibited by our closest relatives in the animal kingdom. He describes one experiment where two unrelated chimpanzees, Peony and Rita, were placed in adjoining rooms separated by a see-through divider. Peony was given a bucket of colored tokens. If she handed the experimenters a red token, only she was rewarded with a snack. A green token got both chimps fed. More often than not, Peony went with green, choosing to take care of both herself and Rita. With this experiment, de Waal became among the first to demonstrate that chimpanzees can have concern for each other’s well-being.

Another example involves Azalea, a now-deceased rhesus monkey who suffered from a disorder similar to the human chromosomal condition Down syndrome. As de Waal explains, “[r]hesus monkeys are quick to punish anyone who breaks the rules, but Azalea got away with almost anything, as if the other monkeys realized that nothing they did would change her ineptness.”

The book is full of similar stories of colorfully named animals diverging from self-interested behavior in the name of helping fellow species members. De Waal makes a short move from these observations to the conclusion that mammals—humans included—are naturally endowed with a capacity to care about each other.

Accounts such as these comprise what are by far the book’s most interesting sections. It’s when de Waal runs his mind over other subjects—say the work of Dutch painter Hieronymus Bosch, or William Golding’s Lord of the Flies or John Steinbeck—that The Bonobo and the Atheist begins to feel like a commonplace book of personal anecdotes, generalizations, and favorite passages. A better title might have been “Pet Theories.”

He returns repeatedly, for instance, to the debate between religious believers and staunch atheists. A nonbeliever himself, de Waal rejects both stances as unacceptably dogmatic, but takes great pleasure in freestyling on the topic. His observations range from the sensible: “Understanding the need for religion is a far superior goal to bashing it”; to the speculative: “The stricter one’s religious background, the greater the need to go against it”; to the ho-hum: “There are many reasons for kindness, and religion is just one of them.”

Of course, there’s nothing wrong with a little abstract meandering, especially from a scientist as accomplished as de Waal. And yet, one can’t shake the impulse to demand that The Bonobo and the Atheist do more to tease out the implications of its “bottom-up” moral theory. Discussing the natural origins of ethics is certainly an edifying project and one to which de Waal has made fresh and worthy contributions. But he leaves us nowhere when it comes to the many other thorny areas of ethical inquiry that his theory butts up against. Say our moral capacities are, to some extent, part of our nature. Can this insight help us to choose between competing moral systems? Or resolve ethical disagreements? Why even bother being moral?

Then there’s this one: what’s the best way to live? De Waal admits that he doesn’t believe “watching chimpanzees or bonobos can tell us what is right or wrong,” and yet he expresses skepticism about various normative theories that enable us to organize our moral instincts, identify our own values, and reach decisions about how to act.

Can you fault de Waal for coming up short on some of the most challenging questions moral theorists have seen fit to investigate? No. But he might have thought to ask a few of them.