Read Online Spillover: Animal Infections and the Next Human Pandemic by David Quammen - Free Book Online Page A

gorillas, all dead, lying nearby in the forest.
    Thirteen gorillas? I hadn’t asked about dead wildlife. This was volunteered information. Of course, anecdotal testimony tends to be shimmery, inexact, sometimes utterly false, even when it comes from eyewitnesses. To say thirteen dead gorillas might actually mean a dozen, or fifteen, or simply lots—too many for an anguished brain to count. People were dying. Memories blur. To say I saw them might mean exactly that or possibly less. My friend saw them, he’s a close friend, I trust him like I trust my eyes. Or maybe: I heard about it on pretty good authority . Thony’s testimony, it seemed to me, belonged in the first epistemological category: reliable if not necessarily precise. I believed he saw these dead gorillas, roughly thirteen, in a group if not a pile; he may even have counted them. The image of thirteen gorilla carcasses strewn on the leaf litter was lurid but plausible. Subsequent evidence indicates that gorillas are highly susceptible to Ebola.
    Scientific data are another matter, very different from anecdotal testimony. Scientific data don’t shimmer with poetic hyperbole and ambivalence. They are particulate, quantifiable, firm. Fastidiously gathered, rigorously sorted, they can reveal emergent meanings. That’s why Mike Fay was walking across Central Africa with his yellow notebooks: to search for big patterns that might emerge from masses of small data.
    The next day we continued on through the forest. We were still more than a week from the nearest road. It was excellent gorilla habitat, well structured, rich with their favorite plant foods, and nearly untouched by humans: no trails, no camps, no evidence of hunters. It should have been full of gorillas. And once, in the recent past, it had been: A census of Gabon’s ape populations done two decades earlier, by a pair of scientists from CIRMF, had yielded an estimate of 4,171 gorillas within the Minkébé forest bloc. Nevertheless, during our weeks of bushwhacking, we saw none. There was an odd absence of gorillas and gorilla sign—so odd that, for Fay, it seemed dramatic. This was exactly the sort of pattern, positive or negative, that his methodology was meant to illuminate. During the course of his entire Megatransect he recorded in his notebook every gorilla nest he saw, every mound of gorilla dung, every stem fed upon by gorilla teeth—as well as elephant dung, leopard tracks, and similar traces of other animals. At the end of our Minkébé leg, he subtotaled his data. This took him hours, holed away in his tent, collating the latest harvest of observations on his laptop. Then he emerged.
    Over the past fourteen days, Fay informed me, we had stepped across 997 piles of elephant dung and not one dollop from a gorilla. We had passed amid millions of stems of big herbaceous plants, including some kinds (belonging to the family Marantaceae ) with nutritious pith that gorillas devour like celery; but not one of those stems, so far as he’d noticed, had shown gorilla tooth marks. We had heard zero gorilla chest-beat displays, seen zero gorilla nests. It was like the curious incident of the dog in the nighttime—a silent pooch, speaking eloquently to Sherlock Holmes with negative evidence that something wasn’t right. Minkébé’s gorillas, once abundant, had disappeared. The inescapable inference was that something had killed them off.
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    T he spillover at Mayibout 2 was no isolated event. It was part of a pattern of disease outbreaks across Central Africa—a pattern of which the meaning is still a matter of puzzlement and debate. The disease in question, once known as Ebola hemorrhagic fever, is now simply called Ebola virus disease. The pattern stretches from 1976 (the first recorded emergence of Ebola virus) to the present, and from one side of the continent (Côte d’Ivoire) to the other (Sudan and Uganda). The four major lineages of virus that showed themselves during those emergence events