Reading your book was like reading Bill Bryson in that you’re able to unlock science in a way that is accessible. How did you approach the writing of it?

The book had 33 chapters and I imagined them like a long camel train. Each camel could only carry so much weight or else the pace would slow or that chapter would collapse under its own weight. I might draft 10 pages on some topic, but often all that ended up being reduced to a few sentences. You have to pack judiciously to keep the caravan moving. For many research projects, the challenge is finding enough material, but this book had the opposite problem—a surplus of great stuff. It involved complicated science such as geology, anatomy, and genetics, plus many backstory threads about characters, Ethiopian politics, or relations with the Afar clans in the fossil fields. When it came time to organize all that, I just decided to let the story flow chronologically and wove in threads of backstory at appropriate points in the narrative. It might seem unoriginal, but chronological organization remains a pretty good way to tell a story and it allowed me to walk the reader through the action of the Ardi saga—search, discovery, reconstruction, secret study, and heated debate. In that sense, the skeleton of Ardi also served as the “skeleton” of the plot. Everything else was just adding flesh to that framework.

You spent more than a decade on the book, including several visits to Ethiopia. When was the moment when you decided you would pursue this project to the ends of the earth? 

I had no idea what I was getting into! Beginning in 2012, I kept telling people that I hoped to finish within a year—and I continued saying that for years. The problem was I kept finding new interesting material or problems that I couldn’t solve right away but also couldn’t ignore. It began like one of those home improvement projects when you start one little job, it grows into a series of other tasks, and you gradually realize you need to demolish everything and rebuild from scratch. I missed my original book deadline not by days, weeks or months but by years. (By the way, this kind of delay is not uncommon in publishing and my agent once told me “it’s the rare book that actually comes in on time.”) I never expected this book would take so long, but I just refused to call it done until I felt confident that I had a sufficient grasp of all the strands of this big, hairy story.

I loved learning about all these obsessed scientists. In that regard your book read like a novel to me. 

I set out to write a book about science, but I couldn’t make the average reader swallow a dry textbook about radiometric dating, extinct pigs, or sesamoid bones. So I had to make this a story about people on a quest to solve a mystery, or actually a series of mysteries. Once I put you in their boots, I could spoon you small doses of science as we march through the quest for an ancient skeleton. Luckily, the central characters were passionate people who made us care about arcane topics such as the subtle features of a fossil foot bone that revealed a grasping toe.  I wanted to keep people turning pages to find out what happened next. Unlike a novel, however, this is non-fiction—it all really happened! Being an obsessive reporter, I took great pains for accuracy. For example, some of the dialog actually came from videotapes that were kept rolling for many hours during the excavation of the Ardi skeleton. If you look in the back of the book, there are more than 80 pages of endnotes and bibliography that tell you the source of just about every fact, quotation, or scene. So far, the critic reviews have been positive and I was most pleased by the one that called the book “meticulously reported.” That’s the line I want engraved on my tombstone. I’m glad the book read novelistically, but I probably was more concerned about accuracy.

I had never heard of Ardi or the fact that this skeleton pre-dates Lucy by more than a million years. Are you finding that this is new information to many readers?

You are not alone. As I wrote in the book, Ardi is the most important discovery for early human origins that most people have never heard about. Lucy undoubtedly was a milestone discovery, but part of her fame was due to non-scientific factors. Her discoverer was a charismatic figure who wrote popular books, starred in television documentaries, and relished the limelight. The Ardi team—which included several veterans of the Lucy team—felt like the Lucy PR hype got out of control and they reacted by taking a more hardcore science approach. They devoted a lot less effort to publicity or building consensus among academic peers. Indeed, the Ardi team included a few combative personalities with a knack for irritating scientific colleagues. By the time Ardi was published in 2009, many peers were eager to see them proven wrong or happy ignore their big discovery. But scientific factors certainly also played a role; the Ardi skeleton disturbed the status quo and it’s always easier to ignore inconvenient information rather than change your worldview. And some scientists didn’t agree with the Ardi team’s style of analysis or conclusions, and that sometimes made people ignore the real fossil evidence behind it. Even though Ardi is the oldest skeleton in the human family, the profession was reluctant to embrace her for years so her name recognition remains relatively low. Maybe that is changing, slowly.

You write about the fierce battle within the scientific community about conclusions to be made by the discovery. Do you feel like accurate revisionist history is starting to be written about the nature of our roots?

Revisionist history always remains a work in progress. After all, science is an ongoing process of self-correction and disruptive discoveries like Ardi invariably arouse controversy. That said, I saw a definite change in the debate during the time I was reporting this story. Gradually, the debate is shifting from whether to include Ardi in the human family to how to do so. There is a growing consensus that Ardi and her species, Ardipithecus ramidus, is indeed a hominin (or what used to be called hominid, defined as a member of the human branch of the family tree after we split from our common ancestors with chimps). A number of independent scholars have agreed that Ardi is indeed a primitive member of our family who reveals a weird evolutionary stage never seen before—a tree climber with a grasping toe who also walked upright on the ground. Ardi is being added to textbooks and I think younger generations eventually will just accept her as an important milestone in our fossil record—just as we do with a lot of other major discoveries that used to be disputed. Hopefully more such surprises are waiting to be discovered.

What was it like being on Joe Rogan’s podcast? 

The Joe Rogan invitation came as a total surprise. Being an old fossil myself, I didn’t recognize his name and had never seen his show. When my publicist contacted me about it, I immediately texted my kids and asked, “Have you ever heard of a guy named Joe Rogan?” They told me he was huge and they were absolutely dumbfounded that their geek dad had been invited onto a show whose other guests included Kanye West, Kevin Hart, and Bernie Sanders. The old man definitely gained a few cool points, although I also lost a few when I went on air and didn’t get Joe’s reference to Game of Thrones. We taped the show right before my book launch so the Joe Rogan Experience was one of my first press events. I was energetic, but probably not very polished in my presentation. Nothing like an audience of 12 million people to alert you to all your shortcomings! That show was my first real encounter with trolls. My god, it was almost funny how much they hated me. Constant Miss Piggy jokes, dumb taunts about my name (“his parents must have really hated him to name him Kermit”), complaints about my style of speaking, and demands that Joe bring on a real guest like Alex Jones or Donald Trump and quit covering all this evolution nonsense. There was so much vitriol that you’d almost think the haters mistook me for Hillary Clinton. But it’s all a big reality show so I try to keep a sense of humor (some of the trolls actually were halfway funny). I wrote a Twitter thread about the experience. Thankfully, Joe himself was delightful and truly interested in the topic. Surprisingly, former martial arts fighter and comedian Joe Rogan wanted to delve into the science more deeply than most of actual science shows.

What’s next for you? Are you going to do more deep dives into science?

Yes, it will be another history of science. I am still fleshing out the story so I shouldn’t say much about it, but I am very excited to finally be working on something new. I learned a great deal suffering through my first book and hope to be more efficient the next time around. I’ve learned one thing: I won’t promise to be done by next year.