Review: Quammen’s Spillover Saw Covid-19 Coming

David Quammen released his book Spillover in 2012, but in the first few months of 2020 his book’s theme resurfaced and he found himself back in the newspapers, interviews, and in numerous television debates.  

Covid-19 has brought the concept of spillover to peoples’ minds: the passage of a pathogen from one species to another, and with it the concept of zoonosis. And also because Quammen seems to have predicted with certain accuracy everything that is happening these days. 

Photo by Gustavo Fring from Pexels

To tell the truth, not everyone is convinced that Covid-19 is an animal virus. The thesis that the virus was produced in a Chinese laboratory or by the Americans, perhaps in an attempt to find a vaccine against HIV, is widely circulating and is continuing to do so. 


Personally, of this thesis, I am only fascinated by the glimpse of a part of human responsibility in the emergency of the disease. This, however, we should not imagine dressed in a lab coat in any laboratory in the world as if we were in a Stephen King novel – by the way, read The Shadow of the Scorpion, which still has many very valid observation points -, but rather as an ecosystem conqueror. The spread of viruses with increasing frequency, in short, would be nothing but one of the many signs of the devastation that the human species is carrying out, without realizing the consequences that it can have. 

Quammen explains it well in the very first pages of the book, in which Hendra is the protagonist: a virus housed in bats and which, from there, made its way first to horses (called amplification guests) and subsequently to humans. 

Let it be clear right away: there is a correlation between these diseases that come up one after the other, and they are not mere accidents but unwanted consequences of our actions. They are the mirror of two converging planetary crises: an ecological and a health one. (…) How do these pathogens make the leap from animals to humans and why does this seem to be happening more frequently in recent times? To put it as smoothly as possible: because on the one hand it seems that the environmental devastation caused by the pressure of our species is creating new opportunities for contact with pathogens, and on the other, our technology and our social models contribute to spreading them faster and wider There are three elements to consider.

One. Human activities are the cause of the disintegration of various ecosystems at a rate that has the characteristics of the cataclysm. (…) Tropical forests are not the only environment in danger, but they are certainly the richest in life and the most complex. Millions of species live in these ecosystems (…). 

Two. Among these millions of unknown species are viruses, bacteria, fungi, protists, and other organisms, many of which are parasites. 

Three. Today the destruction of ecosystems seems to have among its consequences the ever more frequent appearance of pathogens in larger areas than the original ones. (…) A parasite disturbed in his daily life and evicted from his regular guest has two possibilities: finding a new home, a new type of home, or becoming extinct. (…) “If we observe the planet from the point of view of a hungry virus” writes historian William H. McNeill “or of a bacterium, we see a wonderful feast with billions of human bodies available”. 

In this sense, human responsibility is not to be excluded, on the contrary, it is beautiful clear before our eyes, just as the solutions are clear, which should not be applied to deal with Covid19 or some other Next Big One, but to implement behaviors that reduce their room for action. 


In a nice interview with Quammen, the interviewer asked him a provocative question: if the virus comes from the bats, should we kill them all? Quammen’s answer was simply: “No, the solution is to leave bats alone because our ecosystems need bats.” We need bats as well as many other living things, and they need to stay balanced. The human species seems to have forgotten about this fundamental ecological lesson, behaving like the master of the world. 

Photo by Gustavo Fring from Pexels

And in this forgetfulness reside the proliferation of viruses and diseases, but also many other crises of our time, whose effects we already feel, but without being devastated to the point that we still manage to pretend nothing: the climate crisis, the depletion of resources, even viruses … All that afflicts us seems to be attributable to the same perspective: the inexorable work of devastation that we have been carrying out for decades, and the fatal forgetfulness that a constantly forced and severely tested balance, sooner or later breaks. 

Spillover is a phenomenal journey, a beautiful reportage built around the world thanks to constant comparison with scientists and researchers. It reminds us of our responsibilities, but also of our intelligence, and the fact that it is not yet too late to change course. However, we should be able to listen to science, understand where we have gone wrong, take our responsibilities, and act accordingly, trying to prevent the next crisis, rather than simply parrying the blows once it has manifested itself. Understand, ultimately, that we are not the lords of the world, but only a part of it. 

“This is what zoonoses are useful for: they remind us, as modern versions of San Francesco, that as human beings we are part of nature, and that the very idea of ​​a natural world distinct from us is wrong and artificial. There is only one world, which humanity is part of, as well as HIV, Ebola and flu viruses, Nipah, Hendra and Sars, chimpanzees, bats, civet cats, and Indian geese.” 

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