Katherine Harmon Courage is a science writer and author of “Octopus! The Most Mysterious Creature in the Sea” and “Cultured,” a forthcoming book about cuisine and the microbiome.

What is it that compels us not only to gaze at the stars but also to build the technology to reach out to them, study them, understand them? It is, of course, that mysterious, powerful force of curiosity that is with us from infancy, blossoms in childhood and persists throughout our lives. Plenty of animals show a keen interest in objects and situations. But in “Why,” astrophysicist Mario Livio argues that humans are the only species to ask not just what, where or who, but also why.

“Why,” by Mario Livio (Simon and Schuster)

This wide-ranging investigation is no humanist’s dalliance into wonder and whimsy. Commanded by Livio, who worked on the Hubble Space Telescope, the topic is treated with a physicist’s sensibility. Examples (Leonardo da Vinci, Richard Feynman) are put under the microscope, the science (fMRIs, neurotransmitters) is assessed, and hypotheses (do scientists consider themselves curious?) are tested. Livio has the credentials for taking on this unwieldy subject, having authored numerous popular-science books (“The Golden Ratio,” “Is God a Mathematician?” and “Brilliant Blunders,” among others), and is apparently plenty familiar with the topic (the first line of the book is: “I have always been a very curious person”).

His research roves broadly, from historical documents and technical studies to personal interviews. But the result is rather stilted, yoked to the cult of individual scientific genius, embellished with umoored quotations from Western thinkers and delivered in a tone that often reads as didactic. The reader feels less like a fellow discoverer than an undergraduate in lecture.

Like any notable instructor, Livio includes some fascinating tidbits along the way. Perhaps the most interesting and useful segment delves into the role of curiosity in learning and memory. Participants in one study were asked to rate how interested they were in learning the answers to various questions on a list. They were then shown the questions, one by one, followed by the corresponding answer. But the answer was not delivered instantaneously. The subjects sat through a waiting period, during which they saw a brief image of a random face. Later an unexpected memory test showed that people best recalled the faces shown when they were waiting for an answer they had been particularly eager to know. The lesson: Stay curious, remember more.

The curiosity memory boost involves a partnership between the brain’s learning and reward systems. The hippocampus, which is associated with learning, and the neurotransmitter dopamine, which is linked to pleasure, were activated together in a range of studies on the physiological underpinnings of curiosity. “In other words,” Livio writes, “the desire to learn produces its own internal rewards.”

This reward, at times, proves too enticing to Livio himself. He often starts into a promising line of narrative but then quickly veers off to insert a tangential fact, quote or reference before moving on to something else entirely. As a result, the reader must move through a scree field of asides, which have apparently tumbled down from some great unseen monolith of the author’s mind.

This tendency gains a brief reprieve when Livio leaves the scientific literature behind to probe curiosity in living people: paleontologist Jack Horner, rock band Queen’s lead guitarist and astrophysicist Brian May, CERN Director General Fabiola Gianotti and several others. We learn that Horner is largely self-taught, May collects Victorian-era stereophotography and Gianotti received her first degree in music. Although composed of fascinating individuals, his sample leaves something to be desired: Each person is famous, all but two are scientists, and most of them are fellow physicists. It leaves the reader to wonder: Is an impressive accomplishment, unexpected interest or second career the exclusive domain of the rarefied, “very curious person”?

Livio’s elevation of the high-profile scientist as a different breed backs up his premise that “people are not equally curious.” Furthermore, he surmises that “curiosity requires certain cognitive abilities . . . governed to a significant degree by genetic inheritance.” He does ultimately add the much-needed acknowledgement that superstar curiosity is often not attainable for those in dire situations, such as refugees and residents of repressive regimes (Livio’s own parents fled Romania during World War II). Left out of his picture, however, is the majority of humankind, who live neither in a state of constant threat nor in the academic world: those of us who find curiosity in the people and things around us and in the details of our work and hobbies that will never be written up in Science or Rolling Stone. By exalting the few, he undercuts the true beauty of curiosity, which is that it is one thing that truly unites and ignites us as humans.

But he rescues his book with an unexpected moral call that is worth listening to: “Curiosity,” he writes, “is the best remedy for fear.”

We now have an unprecedented ability to quench our curiosity about the specific. Nevertheless, fear of the broad unknown — often in the guise of protectionism or hatred — remains. Curiosity is an overlooked catalyst that can turn such detrimental potential energy into true human progress — which can take us to the stars and beyond.

What Makes Us Curious

By Mario Livio

Simon & Schuster. 252 pp. $26