Rowan Hooper: Bill, when you announced your visit to the office, people reacted as if Ryan Gosling or David Beckham were arriving.

Bill Bryson: That’s just my appeal.

RH: Your book from 2003, A Short History of Almost Everything, has become one of the best-selling nonfiction titles of the 21st century, and you’ve now released a revised edition.

It’s over 20 years old, and science has evolved tremendously since then. Consider the Denisovans: back when I wrote the first edition, little was known about these ancient humans, just like Homo floresiensis – the Hobbit. Revisiting and updating this was gratifying because I reconnected with many experts I first interviewed two decades ago.

RH: One of the most rewarding aspects of being a science reporter is the privilege of speaking with leading experts and engaging them about their groundbreaking research.

For many scientists, their work often goes unnoticed, especially in fields that lack public interest. I’m here to say that their contributions are remarkable and worth discussing.

I always ask, what inspired you to enter your specific field? What was that defining moment that made you passionate about studying, say, lichens?

RH: Shifting gears, what was your own “Eureka” moment in science?

I struggled with science during my school years. Coming of age in America during the 1950s and 1960s, education focused heavily on producing future scientists, which didn’t resonate with everyone.

Yet, I believe everyone should connect with science at some level. Science is foundational—it explains our existence and guides us towards understanding our future. My aim was to engage people in this discovery, sparking curiosity without delving into complexities like equations and technical jargon.

When I first pitched this idea to publishers, they dismissed it as impractical, suggesting I leave popular science to titans like Stephen Hawking. But they eventually allowed me to proceed.

To my surprise, many people are eager to learn about science just as I am. The book’s essence revolves around the question: “How do we know what we know?” It explores the processes scientists use to uncover knowledge.

Remarkably, I found it fascinating how much we still don’t know. The unknown is as compelling as the known.

Understanding that we cannot yet quantify all the insect species on Earth highlights this point.

RH: Many species are disappearing before we’ve even identified them, directly linking to climate change, which isn’t covered in the book. What was the rationale behind that decision?

The book aims to clarify our historical understanding and the current state of knowledge. Thus, its focus leans towards the history of science.

Penny Sarche: One significant change from the initial edition to the new one is the human lifespan—previously 74.2 years, it has now extended to over 80 years. This reflects a major increase in longevity.

Originally, I emphasized that a human lifespan comprises roughly 650,000 hours. Reflecting on all the moments spent idly, like watching Coronation Street, makes me value the time we have.

PS: Did you encounter any unexpected insights while revising this book?

I was amazed to discover that we’ve identified twice as many moons in the solar system. I pondered, “How difficult can it be to keep track of moons?”

In the past 20 years, the number of moons orbiting Jupiter has tripled, with most being relatively small. The definition of a moon is simply a rock that orbits a planet.

RH: Another notable change is the complexity of human family trees, now resembling a hedge rather than a straightforward line. Was that surprising? It seems almost manageable, right?

It was indeed surprising. Experts initially believed they had a solid grasp on human ancestry, but discoveries concerning the Denisovans and other ancient human groups have complicated matters.

What fascinates me is how ancient humans interacted and coexisted. Contrary to popular belief, interbreeding was common among different groups, suggesting a rich and intertwined history.

Alec Luhn: Twenty years ago, the scientific community operated in a calmer atmosphere. Currently, discussions in the U.S. suggest a war on science. Did this create pressure while writing the 2.0 edition?

The main goal of this book is to sustain the dialogue around science for another 20 years, hoping for reflection on the current climate as a temporary phase.

It would be tragic if such policies and institutionalized dissent became a long-lasting aspect of the U.S.

This text is revised from an interview shared on the New Scientist podcast titled “The World, the Universe, and Us.”