David Quammen is the author of the new book The Chimp and the River: How AIDS Emerged from an African Forest. His other books include Spillover, Ebola, and The Song of the Dodo. He is a contributing writer for National Geographic, and he lives in Bozeman, Montana.
Q: You write, “AIDS has been written about many times, from many angles, but the story as told here is drastically different from any version you are likely to have read…” What are the main differences?
A: The big differences in the story as I tell it—based on the recent work of Beatrice Hahn, Michael Worobey, and others—is that the ecological origins of the pandemic HIV strain have now been traced, in both time and geography, and those origins are VERY different from what most people think they know about the pandemic.
Specifically, we now have it on very persuasive evidence, from Hahn and Worobey and their groups, that the AIDS pandemic began with a spillover of the precursor virus (SIVchimp) from a single chimpanzee into a single human, in the southeastern corner of Cameroon, back as early as 1908, give or take a margin of error.
How it simmered for decades among the rural populations and then in the cities of Central Africa (notably Leopoldville, later named Kinshasa), barely maintaining its presence in humans, and then finally exploded into a horrible pandemic during the later 20th century—that’s all part of this little-known and more complicated story, following from the original spillover.
Q: How did you research this book, and what surprised you most in the course of your research?
A: I researched the AIDS story as part of my much longer and broader book, Spillover, in which The Chimp and the River originally appeared as a long chapter, in 2012.
That research involved a combination of information-gathering modes: reading the journal literature, interviewing scientists (usually but not always in person), traveling myself to some of the relevant sites, such as the little Ngoko River draining eastern Cameroon, where I chartered a boat to go downriver toward the cities, retracing what must have been the route of the virus.
The most surprising thing that occurred during my research was when I began reading one of Beatrice Hahn’s crucial papers—it was Keele et al (2006), “Chimpanzee Reservoirs of Pandemic and Non-pandemic HIV”—and looked at the map on its first page. That map showed the small area within Central Africa where, according to the Keele-Hahn results, the pandemic strain of HIV had passed from chimps into humans.
I recognized places on that map. I saw a river I had traveled on, a little village where I had slept, in the course of an expedition for National Geographic. Immediately I thought: If THAT’S where AIDS began, I’ve got to go back.
Q: As you mentioned, this book is an expanded version of a chapter of your previous book, Spillover. Why did you decide to expand that chapter into a book?
A: My publisher for Spillover, W.W. Norton, and my editor there, Maria Guarnaschelli, suggested that they’d like to bring the AIDS chapter out in the form of a small, free-standing book. I had always thought of it as a set piece, almost a book to itself, so I quickly agreed.
I had to reshape the material a little bit, to make it stand alone, but not much. And I wrote a new introduction. I was glad for this chance to get the book into the hands of people who don’t have the time, or the stamina, or the interest, to read a 520-page book (meaning Spillover) on the whole phenomenon of zoonotic disease.
Q: What are some of the other zoonotic diseases you describe in Spillover, and are these diseases becoming more prevalent?
A: There has been what I call a whole drumbeat of newly emerging zoonotic diseases in recent decades. Most of them are caused by viruses: Machupo in Bolivia (1961), Marburg from Ugandan monkeys killing laboratory workers in Germany (1967), Ebola’s first known outbreaks (1976), HIV being recognized (1981, though of course, as I explain in Chimp, it had been among humans much longer), hantavirus in the U.S. (1993), Hendra in Australia (1994), Nipah virus in Malaysia and then Bangladesh (1998-2000), West Nile hitting New York (1999), SARS coronavirus out of southern China (2003), MERS coronavirus from the Arabian peninsula (2013), and many others.
Plus some non-viral zoonoses becoming newly prominent, such as Lyme disease in the U.S. and Q fever in the Netherlands. I talk about all these in Spillover.
Why are such disease events becoming more frequent, more prominent, more consequential? I’d point to three factors.
First, we’re now recognizing some exotic disease events that in decades or centuries past would have gone unnoticed. That’s simply the issue of better detection.
But they are also probably more frequent in absolute terms—because of more humans causing more disruption in more species-rich ecosystems where so many viruses live within their hosts. We shake things up, we eliminate host animals, and we offer the viruses an alternative—us. So they jump aboard.
And once aboard, if they adapt to us and find ways of efficient human-human transmission, they can travel around the world at the speed of an airplane.
Q: What are you working on now?
A: I’m finishing two projects for National Geographic: another article on Ebola, and a special issue on the Greater Yellowstone Ecosystem, for the centennial (2016) of the U.S. National Parks system.
The Ebola article, which is scheduled for July, looks at the big ecological question: Why, after 39 years, have scientists been unable to identify the reservoir host of Ebola virus? The Yellowstone project is a big (but intriguing) task because they’ve asked me to write the entire issue.
I’m also at work, in the research stage, on a new book project, involving the idea of the Tree of Life and the radical challenges to that image arising from recent discoveries in molecular phylogenetics.
It was for the book that I’ve recently been on the road—interviewing molecular biologists in Halifax and Ottawa and Urbana, Illinois, and spending time with the Carl Woese papers archived in Urbana.
Carl Woese is an important character in this story because he, as you may know, is the scientist who discovered the third major domain of life, the Archaea, entirely unknown to the world before his publication in 1977.
That was one form of drastic revision in the traditional Tree of Life. Another form comes from discoveries of the phenomenon of horizontal gene transfer. And there’s more. But that book isn’t written yet so…please stay tuned.
Q: Anything else we should know?
A: Not much. Between research trips to Central Africa or snowy Halifax or the Yellowstone backcountry, I live a quiet life in Bozeman, Montana, with my wife Betsy, two borzois, a maremma, and a very self-possessed cat.
I seem to have used up my knees with 25 years of telemark skiing, but I can still bicycle pretty hard. No more kayaking, no more ice hockey. We all know that it’s hell to get old, but I tell myself that 67 is a wonderful age: way better than 103 or dead.
Otherwise, for fresh air and comic relief and doses of humility, I play golf with my father-in-law, a patient man. I like to hit the ball, and I don’t do the arithmetic.
--Interview with Deborah Kalb