Who is audacious enough to publish a book purporting to explain the answer to the question, What is life? Well, Christophe Galfard is. In his book, This Is Life: How the Science of the Cosmos Explains What We Are, he explains it to the best of our current knowledge in 476 fascinating, highly readable pages.
In the tradition of the very best books of popular science, Galfard uses engaging prose, mastery of knowledge in many realms, and remarkable skills of synthesis to explain what is known about life on Earth from the planet’s origin in a dust cloud, its turbulent early history, through the evolution of species, and inside the cell to the mysteries of DNA. He also covers intellectual history: how we’ve come to know what we know, by highlighting the work of legions of visionary scientists often not well known, including many previously unsung women.
That done and dusted, he asks what everyone who stares at the stars asks: Is there someone else out there?
Paris-born, Christophe Galfard studied at the École Centrale Paris and earned a Ph. D. in theoretical physics from Cambridge under the supervision of Stephen Hawking. Since then, he has become a leading interpreter of science for a public facing an unprecedented wash of false and intentionally misleading claims. His bestselling The Universe in Your Hand (2016) demystifies quantum physics and the enigmas of E=mc². Significantly, on his webpage, Galfard identifies himself as a scientific author and science advocate.
As an advocate, he has a duty to engage, and Galfard does so by writing much of the book in second person, as if addressing a class of eager students. “You are relaxing, peacefully watching the clouds,” he begins one explanation. He also introduces you as an ethereal version of yourself, in other words, pure thought, without the baggage of a physical form. This allows you to witness the asteroid collision that doomed the dinosaurs and travel inside a human cell to watch it fight a virus.
With these devices, the story he tells is structured like a complex modern novel, including rhetorical features like a series of short, sentence-long paragraphs to emphasize a point. Still, This Is Life is a book about science, all branches of science; not just physics but also biology, chemistry, genetics, and bacteriology, and how they are connected. The book sets about “…figuring what we are, where we come from and whether we are alone in this universe of ours.” It is a massive undertaking, but it is accomplished with the skill of an excellent storyteller.
Beginning with Origins
This Is Life begins with evolution as described by Charles Darwin and also Alfred Russel Wallace, who actually had the idea of natural selection first, prompting Darwin to rush out his book. “Part One: Evolution” is not so much about how natural selection works but about emphasizing the world-shattering nature of the very idea of an explanation of life on earth that doesn’t start with “In the beginning…”. Galfard concludes this chapter by pointing out, “In other words, there is no universal definition of life”, though he works hard to provide one.
“Part Two: An Extinction” tells the harrowing history of the universe, especially Earth, with reference throughout to scientific discoveries that have proved the details. Apparently, the Earth and the Moon were once two planet-like masses that collided, with the Earth coming out the better of the impact with a molten core (and chemical-making furnace) and an atmosphere, leaving the Moon, well, the Moon. Incredibly, in 1971 Apollo astronauts brought back a 9-kilogram boulder. In 2019 this “moon” rock “was found to be actually from the Earth, thrown up there by a collision that happened more than 4 billion years ago, only now returned home by human hands.”
Like a rich and clever novel, This is Life is teaming with such fascinating anecdotes that enrich the story while building the narrative. Minor characters also appear with outsized influence on the plot. Darwin and Wallace are here, and Mendel and Pasteur, but so is Mary Anning (1799-1847), an amateur who collected and sold fossils she found around her home. When she was 12 years old, she discovered the first complete ichthyosaurus ever found in Dorset – all nine meters of it.
Similarly unsung is ocean geographer Maria Tharp, who, because of her gender, was excluded from ocean-going research ships in the 1950s. Working from her office and using just the maps and data collected, she discovered the undersea rifts that separate the Earth’s plates. As Galfard puts it, “Tharp had become the brain while all her hierarchical superiors had become data collectors.”
Under the Microscope
The longest, perhaps the most important, and the most challenging, “Part 4: A Journey Within” deals with life at the cellular level. Cognizant of the technical challenges of this section, you, ethereal again, are assigned a teaching assistant by the author, modelled after Marvin the Paranoid Android from Douglas Adams’ 1979 sci-fi comedy, The Hitchhiker’s Guide to the Galaxy. Called the Yellow Robot, it provides helpful but droll commentary when the scientific going gets tough. In this section, Galfard explains the “birth of memory” found in the DNA that connects you and me with extinct algae that existed billions of years ago.
In “Part 5: Domains of Life”, Galfard, as master popularisers do, connects the esoteric with real life by telling the story of the Coronavirus vaccine, along the way explaining the history of the maybe alive, maybe not “lifeform” the virus and its interaction with its arch-enemy, the very much alive bacteria. We meet yet another unrecognized female genius, Hungarian biochemist Katalin Karikó, who came to the US in 1985 with her family to make her scientific fortune.
Her work on using mRNA to fight viruses and create vaccines much faster (which Galfard explains in accessible detail) was constantly maligned and sidetracked. Unfunded by her university, her work eventually led to a COVID-19 vaccine produced at a previously unheard-of speed. Ultimately she left her university for the private sector. The company she joined, BioNTech, had, by spring 2025, Galfard points out, reached a market value “estimated at more than $23 billion”. The icing on the cake came when Karikó and her colleague Drew Weissman shared the 2023 Nobel Prize in Medicine.
Is There Anybody Out There?
In “Part 6: Looking for an Origin”, Galfard presents the current arguments for and against whether life exists elsewhere in the universe and, more importantly, whether intelligent extraterrestrial life exists or once existed. As with what has come before, the science Galfard presents is up to the minute, and what is known is surprising. However, I won’t spoil it for you.
This Is Life is a big book: deep, wide, and important. It could become a key work of popular science in our time, joining, among others, Richard Dawkins’s The Selfish Gene, Carl Sagan’s Cosmos, and Galfard’s own teacher, Stephen Hawking’s, A Brief History of Time.
Made accessible by a teacher’s patience and a storyteller’s rhetorical skill, Galfard takes up big questions in an engaging manner. He covers a wide range of disciplines and synthesizes an enormous range of ideas. Throughout This Is Life, he stresses the power of human thought and ingenuity to look past prevailing thought. He also celebrates the uncelebrated in the sciences, especially women.