Jonathan Kennedy (Torva/Penguin)
FROM the impact of epidemics on the rise and fall of empires to the part played by the Black Death in hastening the transition from a feudal, religious society to a capitalist, secular one, humankind has always taken advantage of (or fallen victim to) “circumstances created by microbes”, argues a new and timely book.
Pathogenesis: How germs made history is the first book by Jonathan Kennedy, who teaches global public health at Queen Mary University of London. He draws heavily on that background, spanning 50,000 years of world history and multiple disciplines to write compellingly and persuasively about the role of infectious diseases in shaping the planet as we know it.
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His book is full of surprises. For instance, the evolutionary success of our species over Neanderthals may have had less to do with our relative sophistication and superiority, and more to do with the triumph of the immune system of Homo sapiens over that of our extinct cousins.
Similarly, Kennedy describes how the Neolithic agricultural revolution enabled the spread of pathogens to the benefit of some and the great disadvantage of others, making the impact of that transformation on human civilisation far more nuanced.
In fact, by moving us away from a nomadic way of life and centralising our food sources, the rise of settled agriculture may have ushered in “a golden age for viruses, microbes and other animals… an epidemiological revolution” that might have had just as much of an impact on the world we live in as the other changes that farming wrought.
The immunity that widely developed as a result may even show in our DNA, with many genetic adaptations roughly coinciding with the switch to an agricultural system.
Too small to easily register in fossil records, the influence of infectious diseases is nonetheless evident as a force running with (or against) so much historic human progress across the globe, driving political and economic change.
For Kennedy, infectious diseases have been a guiding hand at every stage of humanity. For example, the Antonine and Cyprianic plagues in the 2nd and 3rd centuries may have been a factor in transforming Christianity from a small sect into a global faith, with the promise of everlasting life after death never more attractive than in the face of widespread mortality.
Much later, towards the end of the 17th century, a Scottish attempt to set up a trading post in Central America was devastated by an outbreak of yellow fever, leading to the threat of financial ruin for Scotland, a bailout from England and, ultimately, the Act of Union in 1707, which saw the countries combine to become the United Kingdom of Great Britain.
When it comes to its relevance to current events, Pathogenesis isn’t just timely because we are living through a pandemic. As Kennedy observes, for all the clichéd talk of unprecedented, extraordinary times, “when we place coronavirus in its historical and scientific context, it becomes very clear that there is little about it that is new or remarkable”.
The advent of covid-19 has transformed our world, just as the Black Death and past waves of disease did. Kennedy shows that the widespread sense of there being a pre and a post-covid-19 era – like a “before and after” marker in time – is justified and likely to be borne out by history.
Pandemics, however, will keep coming, exacerbated by the worsening climate crisis. As he warns in his brief, but sobering, final chapter on “future plagues”, H. sapiens now finds itself in “a very precarious position… surrounded by innumerable viruses and bacteria that are mutating all the time” and face-to-face with the existential threat of infectious disease.
At this moment of reckoning over humankind’s planetary footprint, Pathogenesis offers a humbling reminder that history is made not by the great or the good, but by those who survive – and that we are just another species of animal.
Elle Hunt is a writer based in Norfolk, UK
