The Viral Storm by Nathan Wolfe

that the most compelling explanation for P. falciparum was that it had been an ape parasite and only jumped over to humans through a bite by some confused mosquito, sometime after our split with the chimpanzee lineage. Human malaria had, in fact, originated in wild apes. In the years that followed our work, a number of researchers documented more and more of the parasites in wild apes.
    Subsequent work by my collaborators Beatrice Hahn and Martine Peeters (the same scientists who have done work on SIV evolution) has shown that the malaria parasites infecting wild apes are even more diverse than our study indicated. They have shown that the ape parasites most closely related to human P. falciparum exist in wild gorillas, rather than chimpanzees. How these parasites have been maintained among wild apes and whether or not they’ve moved back and forth between chimpanzees and gorillas remain questions for future studies. Either way, there is no longer any doubt that human P. falciparum moved from wild apes into humans and not in the opposite direction.
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    That malaria crossed from a wild ape into humans makes great sense when viewed from the perspective of the evolution of our lineage. The microbial cleansing that resulted from habitat change, cooking, and population bottlenecks among our own ancestors had cleared our microbial slate, decreasing the diversity of microbes that were present before. Perhaps the many years with leaner microbial repertories had also decreased selective pressure on the many innate mechanisms that we have to fight against infectious diseases, effectively robbing us of some of our protective disease-fighting tactics.
    In more recent times, as our population sizes began to increase, wild ape diseases, some of which we’d lost millions of years earlier, had the potential to infect us again. When these diseases reentered humans, they acted on us like uniquely suited novel agents. Malaria was not the sole microbe to make the leap from apes to modern humans, and the stories of others, like HIV, tell a strikingly similar tale. The loss of microbial diversity in our early ancestors and the resulting decrease in their genetic defenses would make us susceptible to the microbial repositories that our ape cousins maintained during our own microbial cleansing. While we continued to change as a species, yet another part of the stage would be set for the brewing viral storm.

4
    CHURN, CHURN, CHURN
    The oysters were excellent, but the company was even more striking. As I sat in the small Parisian bistro with a tray of fresh shellfish, I savored the taste of the ocean. But the more powerful memory of that day was of another patron of the restaurant. At the table next to me sat an impeccably put together Frenchwoman. Her bag, skirt, and socks all matched—not exactly, but just enough to notice. Her dining companion sat to her right—a miniature poodle, sitting on the chair and drinking water from a bowl on the table. Pieces of his meal—chicken I think—fell over the side of his plate, mingling with the crumbs from his owner’s bread.
    Dogs play an important role in the lives of many people around the world. I had stopped only briefly in Paris on the way home from a month-long trip conducting research in Asia and Africa. It might have been the jet lag, but my recollection of the event could only be described as surreal. During my trip I’d spent time in a part of Borneo where people eat dog, including on at least one occasion my unsuspecting self. I’d also visited Muslim areas of the Malay Peninsula, where devout people won’t even touch dogs because of religious beliefs. And I’d spent time in central Africa, where I’d seen local hunters work with their small, silent basenji hunting dogs—dogs that lived on their own but in exchange for scraps followed hunters into the forests, helping them catch their prey. In the United States, many people treat dogs as members of their families, paying