Because the history of humanity is also a history of viruses and bacteria

A few days ago, Gilberto Corbellini, in reviewing the Italian translation of “Contagi”, written by Kyle Harper, rightly underlined how that formidable book is “a non-human-centric history of infectious diseases”, in which “the protagonists are parasites and biological traits that allow these masters of the planet to invade and use the human world as an environment for adaptation”. It so happens that I have finished reading a book that is truly consonant with the one reviewed by Corbellini, namely “Pathogenesis – how germs made history”, written by Jonathan Kennedy, who teaches global public health at Queen Mary University of London. Also in this case, the reader has in his hands a history of infectious diseases in which the perspective is the furthest from the anthropocentric vision to which we are accustomed, in the face of a numerous and well-selected mass of scientific data: parasites, to put it in short, they are not accidents interfering with the flow of human affairs, like a meteorite falling causing great devastation, but not interfering further. Instead, they are a living part of the construction of all historical events, in a way that I would like to explore here with the reader, and which concerns not only our scientific vision of the world, but above all, and even more, the way in which we tell ourselves our same story, and the biases and erroneous perspectives with which we do it.

In general, anyone who stops for a moment to reflect on the facts that modern science presents us can only agree on how insignificant our species is in the great general picture of things: I think no one can reasonably object to the idea that we are little more than a recent and absolutely peripheral and marginal epiphenomenon in the universe, and, even on our planet, we represent nothing more than a temporary evolutionary branch in a completely extinct group of primates, with a impact on our planet which, however profound it is and begins to endanger our very existence, is certainly no greater than that of the first photosynthetic species or of certain insects or fungi or of the sun; all net of our great and understandable admiration for our cognitive faculties and for our knowledge, both of which, however, are irrelevant and not necessarily of particular interest to any species other than our own.

And yet, although this type of consciousness is quite widespread and even gives rise to frankly impassable ideologies, we still understand nature and our planet (and perhaps the cosmos) as a sort of theatrical backdrop on which history par excellence unfolds, i.e. that of humanity. Traditionally, textbooks told how individuals, generally males, would have determined this history, both positively and negatively: we all know Alexander the Great, Napoleon, Stalin or Hitler, and any history book devotes ample space to their events and presenting them as creators of changes and destinies of vast human multitudes (moreover often focusing on the history of the West and forgetting women). The alternative to this historiographic vision as a biography of great men consists in the modern vision, taught in schools since fairly recent times, which we could say is the vision of, for example, a Legoff or a Febvre: the gaze focuses on daily life and the efforts of large masses of people who often struggle against circumstances and oppressions of various kinds, thus introducing a framework of a different nature, that of a history of humanity which is made up of collective tendencies, very hardly the product of single individuals, and in which innovations , specific acts and cultural changes are never attributable to the action of individual heroes or champions. History, in this modern view, arises from below and from circumstances, and not from the action of special individuals.

Kennedy’s book, perhaps to an even greater extent than Harper’s, further widens the view: history, the author teaches us, is by no means the exclusive product of the action of humanity, however inclusive and general one wants to be. considering all human beings who have ever lived. Viruses, bacteria and microbes of all sorts, capable of attacking both the human body and that of the plants and animals on which we depend, as well as our individual physical bodies, have also continuously influenced the formation of the social, political and cultural body; and this happened and happens continuously, because, in the Darwinian pursuit between the genotype of populations of trillions of rapidly mutating pathogens, on the one hand, and the equally rapid cultural adaptation and the extended phenotype of hundreds of thousands, before, and today of billions of human beings, the race is open, and its direction is indeterminate. Wanting to deepen an aspect that the author leaves to the reader’s intuition, the truth is that we live in a gigantic Darwinian feedback mechanism: our every adaptation to pathogens, our temporary victory, is nothing more than a selective factor that leads to differentiation of new pathogens, i.e. of new matter organized by the genetic code of multiple Darwinian replicators, capable of quickly regaining the lost ground and taking advantage again of the sources of low-entropy compounds that our bodies and those of domestic organisms are capable of provide.

Furthermore, I would like to add here, not only pathogenic microorganisms enter the same race, but also our commensals and symbionts: these, by competition, can keep our pathogens at bay to their own advantage (think of the role of viruses in controlling strains virulent bacteria in our intestines or to that of symbiotic bacteria in contributing to the correct development of our immune system), or they can influence our behavior, or they can also allow the adaptation of human populations to the consumption of food resources typical of specific environments and conditions . This continuous interaction with the internal and external microbiome, an interaction of which disease and epidemics are only one of the possible manifestations, has strongly influenced the entire historical path of our species, as both Kennedy and Harper demonstrate extensively and scientifically : that is, our history is the path we have taken together with an enormous quantity of microorganisms, and the most important facts in determining what is written in ink in school books were first written at least partially in the genetic code of some particular microorganism. It is not our story that unfolds, but that of a great river of genes and of the organisms in which they are carried, of which human beings are the active engine and passive vehicle at the same time, in the great feedback loop that does not allow us to isolate one actor on the other.