History Is Shaped by Germs Not By Humans

 
   

In his new book  Pathogenesis Dr Jonathan Kennedy argues that Infectious diseases have been the driving forces of human history.  Diseases have shaped humanity, from the development of agriculture to the global rise of religion, he says. Dr Kennedy is a visiting fellow at Queen Mary University, London where he teaches in global health policy.
 
The dominance of homo sapiens and extinction of Neanderthals was likely the result of disease, he told Kim Hill.
 
“I always went along with the dominant view that homo sapiens survived, whereas Neanderthals became extinct, because we were more intelligent.
 
“This is such a dominant argument that it's even inherent in the name that we give to ourselves, homo sapiens or wise humans, whereas the Neanderthals, in the 19th century were sometimes even referred to as homo stupidness. Stupid man or stupid humans.”
 
Over the last 20 years there's been an increasing amount of evidence that shows Neanderthals weren't that different to us, he says.
 
“They painted on cave walls, they used medicinal herbs to treat various illnesses, they buried their dead, they talked to one another.”
 
So why did they disappear 50,000 years ago? Most likely homo sapiens gave them diseases for which they had no resistance, he says.
 
“We had been separated from Neanderthals for over half a million years, we'd been living in tropical Africa, and they'd been in western Eurasia.
 
“We'd been living in totally different disease environments. And when we started to push out of Africa 60,000 years ago, we were carrying diseases that the Neanderthals hadn't developed any resistance to.”
 
When we met with the Neanderthals in the eastern Mediterranean, they died out, and we survived as homo sapiens came from a more tropical; microbe rich environment, he says.
 
Thousands of years later in the 14th century infectious disease wiped out two thirds of the world’s population, but the cataclysm of the Black Death also unleashed a period of extraordinary innovation and social change, he says.
 
“It basically kickstarted a series of events that over decades, and even hundreds of years created the world in which we now live, a world in which it's no longer a feudal society where you have these warring Lords a bit like Game of Thrones, and then at the bottom of the social pyramid, you have serfs who are working on their, on their little strips of land and just trying to try to scratch a living.”
 
Feudal society couldn’t function without plenty of serfs to exploit, he says.
 
“The serfs realised that suddenly labour was in great demand. And cultivatable land was really, really plentiful, so they struggled for the better terms.
 
“And certainly, in England, this led to a situation where 100 years after the Black Death, the vast majority of serfs have won their freedom.”
 
Human history from the adoption of agriculture about 12,000 years ago is punctuated by these devastating pandemics, he says.
 
“Infectious diseases have been one of the real driving forces of human history. And I think this is an interesting way to think about the world because often when we think of history, we focus on the role of great men and great women in really kind of rushing historical change.
 
“But actually, when we look at history through this perspective, we see that in many ways, infectious diseases, are the real tidal force that's pushing the past forward.”
 
Just as disease has shaped human society, so too has human collaboration, he says. Overcoming the squalor that accompanied the industrial revolution in England is an example.
 
“The industrial revolution reaches its height in the middle of the 19th century and you have unprecedented economic growth, you have this massive creation of wealth.
 
“But at the same time, health among the majority of the population, in Liverpool and Manchester, which are the centres of the Industrial Revolution, life expectancy for factory workers falls to 15 in Liverpool and 17 in Manchester. This is really, really catastrophic.”
 
The only way to overcome this massive public health crisis was through democratisation, he says.
 
“These new local politicians that were really driven by an ethos of public service. And they directly tax the middle classes and indirectly taxed the lower classes, the factory workers, and they spent enormous amounts of money on sanitation systems and drinking water, and then later improving health systems.
 
“And this is what enabled the UK to kind of have this massive transformation in life expectancy at the end of the 19th. And the first half of the 20th century, this this massive investment in public health and wellbeing.”
 
Covid reminds us, he says, that collaboration on that scale will be needed in the future with scientists predicting another Covid-like pandemic could emerge in the next 50 years.
 
“I'm certainly not the first person to say it but we need to rethink the focus that we have on economic growth and think about how that economic growth can be used to improve the health and wellbeing of the majority of the population because money in and of itself is of no use. If you're dying at a young age or living a very unhealthy life.”

 Listen to the full conversation  on the podcast.

 
Jonathan Kennedy: how germs made history. By Kim Hill. Radio New Zealand, May 6, 2023.
 

Instant Genius is a bite-sized masterclass in podcast form. And in this episode, we're exploring how human diseases have shaped global history.

Over time, we have become infected with various viruses, bacteria and other microorganisms, which have had a huge impact on our evolution. Dr Jonathan Kennedy, a reader in politics and global health, tells us about the close links between disease and colonialism, how infection shaped the migration of humans out of Africa, and what we can all learn from the COVID pandemic.

 Instant Genius Podcast: How human disease changed history, with Dr Jonathan Kennedy. By Alice Lipscombe-Southwell.  BBC Science Focus,   April 3, 2023

Forget ‘great men’ – infection and disease are the really important forces in the development of humankind, believes public health specialist Jonathan Kennedy
 
Barts pathology museum is usually open to the public only by special appointment. But today, I’m in luck. I find myself with an unexpected open sesame in the form of Dr Jonathan Kennedy, the director of the MSc and iBSc global public health programmes at Barts and the London Medical School, and while he has his photograph taken up on one of its mezzanine floors, I’m free to wander around alone. (At least, I think I’m alone; the museum is nothing if not ghostly.)
 
On the same site as the hospital in the City of London, this purpose-built, glass-roofed Victorian building is home to about 4,000 medical specimens, the majority of them displayed on open shelves. Every part of the body is represented and every kind of illness and injury – though tracking down a particular condition can be tricky for the non-medical. When I finally find the gnarled, yellow spine of a patient who suffered from tuberculosis – I was after something that speaks to Kennedy’s new book, which is about infectious disease and its effect on human civilisation – it’s largely down to luck. The vertebrae in question just happen to be next to the museum’s most famous exhibit: the skull of John Bellingham, who assassinated the British prime minister, Spencer Perceval, in 1812.
 
In Pathogenesis: How Germs Made History, there is no mention of Perceval. But Bellingham’s skull, preserved after the dissection of his body that followed his hanging, inevitably brings to mind Kennedy’s chapter on the Industrial Revolution – a period when previously uncommon pathogens such as TB and cholera began to thrive in our cities (cholera did not appear in Europe until the 1830s, having hitched a lift in both the guts and the linen of travellers from south-east Asia). Not only did infectious diseases then account for 55% of deaths in London; cholera epidemics in particular also led to a rise in the public’s distrust of doctors, who were sometimes attacked as they transported suspected sufferers to hospital for isolation.

 
Murderers’ bodies were sent for dissection by law, as Bellingham’s had been; the medical profession was hungry for cadavers and this ensured a supply line. However, as Kennedy notes, the 1828 murders committed by William Burke and William Hare, who sold their victims’ bodies to Edinburgh University’s medical school, caused people to believe that cholera patients, removed from their communities by doctors, were about to be similarly dispatched. The “anatomists”, of course, were absolutely right to compel isolation, but most of their patients would indeed die, even if they didn’t kill them personally. So far as treatments went, doctors were clueless. One of their more bizarre cures involved injecting turpentine and mutton stew into the patient’s intestines via the anus.
 
Kennedy’s book, which aims to show how infectious disease has shaped us from the time of the Neanderthals to the era of Covid-19, is full of amazing facts like these. For days after I read it, I kept thinking of Pope Clement VI who, when the Black Death reached 14th-century Avignon (where he was exiled), retired on the advice of his physician to his chamber, seeing nobody, and spending all day and all night between two great fires – the flames of which kept the rats that were carrying the disease at bay. Clement did very well to survive. It’s estimated that somewhere in the region of 60% of the population of Europe (about 50 million out of 80 million people) died from the plague between 1346 and 1353. Meanwhile, the economy more or less ground to a halt.
 
Kennedy is a sociologist who somehow ended up – he describes “a meandering intellectual journey” – in public health. “Before coronavirus, I published a paper looking at the links between populism and vaccine confidence,” he says. “So when the outbreak started, the rational thing to do as an academic might have been to get my hands dirty working on Covid-19. But actually, I struggled with the way my work was suddenly the news and so I went in a slightly different direction.
 
“With Pathogenesis, I wanted to broaden [the discussion] out. In the pandemic, most experts stopped saying ‘this is an aberration’ pretty early on, for the simple reason that if you look back, you can see that it really isn’t exceptional. Over the course of human history, it has been normal to have these pandemics that not only kill a lot of people and bring civilisations crashing down, but which also, sometimes, create space for new kinds of societies to emerge. The book is an intellectual response to the slightly myopic way some people viewed the pandemic. It’s a long view, one that we couldn’t perhaps take at the time because everyone was in such a panic.”
 
It’s hard to overstate the role that infectious diseases played in the foundation of the Spanish empire
Pathogenesis doesn’t only cover thousands of years of history – it seeks radically to alter the way the reader views many of the (often very well-known) events it describes. Having read recent research by scientists, archaeologists and anthropologists, for instance, Kennedy suggests that Homo sapiens became the dominant species of human not as a result of any inherent intellectual superiority over Neanderthals, but because our immune system was better suited to adapting to pathogens as we migrated north from Africa. He also looks at the role disease played in colonisers’ ability (or not) to govern their empires.
 
It’s generally accepted that Rome fell partly because of plague (probably smallpox), its armies weakened by illness. But by his telling, had it not been for an Ebola-like pandemic in the second century, Christianity would never have become so widespread – a slightly more surprising analysis. What part, he asks, did pathogens play in the near-miraculous victories of conquistadors such as Hernán Cortés and Francisco Pizarro in Central and South America in the early 16th century? Kennedy, as you will have gathered, doesn’t believe in the so-called great man theory of history. He believes in the sick man theory of history, for no soldier can march if he is dying and no king can rule who is weakened by infection.
 
With this book, he set himself a mammoth task. Where on earth did he start? “Well, I guess my starting point was microbes,” he tells me (we’re in a seminar room now, far away from all the pickled lungs and hearts). “Within us, there are 40 trillion bacteria. They’ve evolved over millions of years and we now know they’re playing all sorts of roles in our lives. This blows my mind and the question I wanted to ask as a sociologist was: if these tiny things have such an influence on our bodies, what kind of effect might they have on the body politic, the body social, the body economic? Humans make history, but not in circumstances of their own choosing. Microbes are a huge force in creating those circumstances.”

 
Together, we roam haphazardly over some of the history in his book. I want to know what he found most mind-boggling. “One thing that really came out of the whole project was the absolute baselessness of white ideology,” he says. “Obviously, that comes to the fore when we’re discussing colonialism. It seems bizarre to me now that people would put down Pizarro’s conquering of the Inca empire with only 168 troops to the fact that he had superior weapons. It’s hard to overstate the role that infectious diseases played in the foundation of the Spanish empire.” The Spanish brought smallpox with them, among other diseases, which devastated the Indigenous population. This was followed by measles, an infection now thought to have been similar to salmonella, and flu. Local populations fell by 90%. The Spanish invaders interpreted all this as a sign that God supported them.
 
Yet we cling to assumptions about superiority. “Ever since we discovered the Neanderthals were a separate species, we have dehumanised them, seeing them as these brutish cave men,” Kennedy goes on. “But it seems like they were just as smart as us. They could talk, they created cave art. They buried their dead and observed rituals. To realise that Homo sapiens were migrating out of a tropical region, and that they were carrying more microbes, and that the Neanderthals further north struggled to deal with those… it’s a neat reflection of the arguments about colonialism.”
 
In the context of our own times, Neanderthal man is particularly interesting to him. We now know that Homo sapiens and Neanderthals interbred, with the result that we carry their genes. The Neanderthal genome has, moreover, been sequenced (by Prof Svante Pääbo, the winner of the 2022 Nobel prize for physiology), and papers published since have shown that Neanderthal gene variants in the contemporary population have had an impact on responses to Covid (those carrying one such variant were 22% less likely to end up in intensive care compared with infected people of the same age). “It’s crazy to think that something that happened 60,000 years ago impacts on whether or not we have a really terrible reaction to Covid,” says Kennedy.
 
But if he is fascinated by the past, he’s also concerned about the future. “We’re living in a golden age for microbes. Population densities are increasing, people are moving more quickly around the world, the climate is changing. We’ve seen the emergence not just of Covid, but of HIV/Aids, Zika, Dengue fever, Sars and Ebola. It seems now that we won’t be able to conquer infectious diseases. Rather, we’re going to have to learn to deal with the new diseases that periodically arrive to threaten us.” If history teaches us anything, he believes, it’s that things will only change in terms of health if we stick together: “These are global societal issues. If one rich country tries to save itself, it’ll still be doomed.”
 
Has writing Pathogenesis made him feel pessimistic? On balance, it hasn’t. While antibiotics may soon cease to be effective in treating some illnesses, a prospect he finds frightening and “hard to fathom”, in the future microbes may themselves provide the solution: “Viruses might be the new antibiotics. They kill about half the bacteria in the world every day. It’s about finding the right one to target the right bacteria.”

 
He thinks of Antonie van Leeuwenhoek, the 17th-century Delft haberdasher who pioneered the microscope. “No more pleasant sight has ever come before my eyes,” wrote Van Leeuwenhoek, enraptured by the teeming new world he saw beneath his lens. There is, Kennedy says, still so much to discover. “We’re incredibly vulnerable as a species, but we’re also incredibly ingenious. A hundred and fifty years ago, we didn’t even know that microbes cause infectious diseases. Now we’re analysing Neanderthal DNA.”
 
 
‘We’re in a golden age for microbes’: the man rewriting history from the perspective of germs. By Rachel Cooke. The Guardian, April 2, 2023.

Penguin

The evangelical right is always waiting for the Apocalypse, counting the days, charting signs and wonders, making calculations as to the time and hour of the end times. One would think that in 2020, when the world was faced with a global catastrophe and a complete breakdown in the normal order of things, they would seize on Covid-19 as a sure sign that those days had come. But for the most part, they chose to deny rather than embrace the coronavirus: Their president and their pastors downplayed its severity and its impact, claimed numbers of deaths were exaggerated, and ridiculed those taking it seriously. Rather than embrace the end of days, they demanded a return to the way things were.
 
Perhaps this has to do with the realization that many of us faced in those early months of 2020: that we were suddenly and radically living on the virus’s terms, not our own. Instead of a grand battle of good and evil with humans at the center of the action, we were obligated to learn and adapt our behavior to a nonhuman organism whose motives and purpose were incomprehensible to us. How was it possible, in such an ordeal, to maintain the supposed truth of Genesis 1:26, that God intended humanity to have dominion over livestock and all of nature? Perhaps the coronavirus had dominion over us, and we were the livestock?
 
Jonathan Kennedy’s Pathogenesis: A History of the World in Eight Plagues takes this idea as its inspiration, asking us to rethink our relationship to the bacteria and viruses that drive pandemics. Perhaps, Kennedy suggests, we are not the grand protagonists to our story; perhaps we are just bit players in a larger drama. He retells the story of human civilization from its earliest prehistoric roots to the current decade, not from the perspective of its Great Men so much as its Great Diseases—the bacteria and viruses that have dogged us since Homo sapiens emerged as a species. For Kennedy, it is smallpox, yellow fever, and malaria that matter far more than Charlemagne, Cortes, or Napoleon; he argues not only that “humans have a far less significant place in the world than we used to think” but also that “microbes play a much more important role than we would have believed just a few years ago.”
 
Quoting Stephen Jay Gould, who wrote that “on any possible, reasonable, or fair criterion, bacteria are—and always have been—the dominant form of life on earth,” Kennedy argues that we are as much a product of disease as we are of any conscious decisions. “Outbreaks of infectious diseases have destroyed millions of lives and decimated whole civilizations,” he writes in his introduction, “but the devastation has created opportunities for new societies and ideas to emerge and thrive. In this way, pathogens have been the protagonists in many of the most important social, political, and economic transformations in history.” A radical thought: What if we, for all our hopes, dreams, and best laid plans, are nothing more than the raw material used by bacteria and viruses to shape the world in their image?
 
Kennedy lays this argument out through reframing well-known historical events in terms of the diseases and epidemics that led to them. The rise and fall of empires, the brutal conquests of colonial powers, the map as we now know it—all this has depended far more on disease than we may have thought. Some of this may sound familiar: for example, the fact that European settlers in North America, both intentionally and unintentionally, used smallpox to wipe out Indigenous populations, to make the work of colonizing easier. Entirely new to North America, smallpox “raced ahead of the Spanish,” in Kennedy’s words, devastating whole communities. The disease proved decisive: “Without the help of Old World pathogens,” he argues, “early efforts to colonize the American mainland foundered.” Take, for example, the Spanish conquistadors’ attempts to take Tenochtitlan. The first try failed, but a second expeditionary force arriving a year later brought with it smallpox, which devastated the city and brought the Spanish victory.
 
More subtle was the arrival of the Puritans and the settlement of Plymouth Colony. Earlier attempts to build colonies in New England had faced fierce resistance from the Indigenous peoples already living there. The Popham Colony in southern Maine failed after 14 months; the French trading post near Cape Cod also fell to Native attacks. But these earlier attempts laid the groundwork for the Puritans by spreading disease; when the Pilgrims got there, they found abandoned villages with grain and beans that they used to get through their first winter, the remnants of Native communities destroyed by smallpox. While these Europeans claimed this food as “God’s good providence,” Kennedy suggests instead that “their gratitude at Thanksgiving should be directed to the Old World pathogens that made the settlement of Plymouth Colony possible.” The rest, unfortunately, is history—crucially, in Kennedy’s version of events, the real colonizer of the Americas was the variola virus, with the Spanish and English as merely its unwitting hosts.

 
Other examples that Kennedy invokes may be more surprising. Despite the Roman Empire’s vaunted aqueduct and sewer systems, he explains, Romans’ lack of any understanding of germ theory meant that their water infrastructure festered with disease, hastening the empire’s downfall. Citing Kyle Harper’s The Fate of Rome, Kennedy argues that “pandemics caused immense damage and played a crucial role in weakening the Roman Empire,” far more so, he claims, than the “Barbarians” at the gates.
 
Pathogenesis also convincingly argues that the birth of the nation of Haiti, and perhaps even the rise of the United States in its current shape, can be traced to yellow fever and the humble mosquito, Aedes aegypti, its primary host. In 1802, about a decade after the outbreak of the Haitian Revolution, Napoleon sent an expeditionary force of some 30,000 troops to its former colony Saint-Domingue, hoping to retake the land and reimpose slavery. The freed Haitians, however, defeated them not with military might but with disease. As the rebels’ commander, Jean-Jacques Dessalines, told his troops in March 1802, “The whites from France cannot hold out against us here in Saint-Domingue. They will fight well at first, but soon they will fall sick and die like flies.” Dessalines’s army used the island’s yellow fever against the invading French: It avoided a straightforward conflict when Napoleon’s troops first arrived in spring, drawing them into a quagmire that lasted until summer, when the rains came. With the rains came standing water, the perfect breeding ground for Aedes aegypti, the mosquito that carried yellow fever and proved a crucial ally against the French. According to one historian’s estimate, of the 65,000 French soldiers sent to recapture the colony, more than 50,000 died, overwhelmingly from yellow fever.
 
Unable to maintain their Caribbean outpost, the French ultimately sold the sprawling Louisiana territory to the United States; a fact that leads to Kennedy’s conclusion that the U.S. as it exists today owes a great debt of gratitude to Haiti’s mosquito population.
 
Again and again, Pathogenesis suggests that the course of history has less to do with our own volition and more to do with the ways in which different diseases fared in different climates. In places where Europeans were less susceptible to disease, such as North America, colonizers brought families and established settlements that eventually became wealthy democracies. In places were Europeans were more susceptible to pathogens, such as sub-Saharan Africa, they built rapacious, extractive industries meant to maximize profit with minimal exposure to the environment, men plundering all they could before returning to their families in Europe healthy and wealthy. What they left behind were landscapes ripped of natural resources and countries that, decades later, still struggle to achieve any kind of remote economic parity with former colonial powers.
 
At times, the thesis seems stretched a little thin—Kennedy argues that the rise of Christianity over Roman pagan religions can be traced to its version of the afterlife, an afterlife that became attractive in the face of repeated plagues and pandemics. But it would seem that if the issue here is simply mortality, the Roman Empire’s ceaseless warfare might drive soldiers into embracing Christianity’s afterlife as well. At other times, Kennedy’s desire to offer pandemics as the key behind all of human history means Pathogenesis can veer into the same territory as the kinds of books he critiques—Yuval Noah Harari’s Sapiens and Stephen Pinker’s Enlightenment Now: The Case for Reason, Science, Humanism, and Progress, among them—books that offer “this one weird trick” to explain all of human history.
 
But this quibble doesn’t detract from the main idea that drives Pathogenesis. What the book reveals is the plain fact that humans are often not the only actors on the great stage of history that we assume we are, and that we may not even be the most important. We have used and been used by diseases so repeatedly that, by the end of Kennedy’s book, one begins to wonder if we may exist primarily to spread and promulgate microscopic organisms and viruses. And if that isn’t our main purpose, it certainly remains something we are exceedingly good at—a true calling, you could say.
 
Our diseases, ourselves. For pathogens need us as much as we need them; the story here is of the interdependence of us and the microbes inside us. Rather than showing how insignificant humans are in the grand scheme of the universe, the true effect of Kennedy’s Pathogenesis may be to invite us to further rethink our long held binary that attempts to separate the human from the rest of the living organisms on this planet.
 
It also helps to put the last few years in greater context. If one sees human history as more or less constantly engaged in a complicated dynamic with microbes, creating and responding to pandemics, then the Covid-19 outbreak is less of an apocalyptic interruption in the world, heralding the end times, and instead the latest way in which humans have played hosts to yet another player on the world stage.
 
Are Germs the Main Characters in History? Outbreaks of disease may have had a greater effect on the course of events than the actions and plans of humans. By Colin Dickey. The New Republic  ,May 3, 2023. 

Most accounts of humanity’s origins, and our evolution since, have understandably put Homo sapiens center stage. It was our ingenuity, our tools, our cultural savvy that enabled our species to survive long past others—that allowed wars to be won, religions to blossom, and empires to rise and expand while others crumbled and fell. But despite what the schoolbooks tell us, humans might not be the main protagonists in our own history. As Jonathan Kennedy argues in his new book, Pathogenesis: A History of the World in Eight Plagues, the microscopic agents behind our deadliest infectious diseases should be taking center stage instead. Germs and pestilence—and not merely the people who bore them—have shaped inflection point after inflection point in our species’ timeline, from our first major successful foray out of Africa to the rise of Christianity, to even the United States’ bloody bid for independence.
 
Three years after the outbreak of a devastating infectious disease with a staggering death toll, spending time with a book that vividly details the microbial richness of human history might not rank high on most people’s must-do lists. But those with enough of an epidemiological appetite to pick up Kennedy’s new book will be gratifyingly—if not necessarily cheerfully—rewarded with the knowledge that their read was at least well timed. Epidemics, Kennedy reminds us, are not aberrations in our overstuffed, interconnected, climate-change-fractured world. And when the next one arrives, as it surely will, our response to it will be better if we remember, and avoid, the many mistakes of the past.
 
Kennedy’s book isn’t meant as revisionism; the broad strokes of history remain intact. But it gently sidelines humans—and, in doing so, humbles them. In the grand scheme of things, he writes, we have far less influence over the fate of our own species than we might like to think: “Very often we don’t make history in circumstances of our own choosing, but in circumstances created by microbes.” Humans aren’t alone, even in their own tale. We’re constantly being puppeteered by our viral, bacterial, and parasitic passengers—simply riding a narrative arc that’s been constantly bent by our bugs.
 
Consider, for instance, the vanishing of the Neanderthals, one of the early human species that lived alongside and interbred with ours. Neanderthals were once perceived as brutish and dumb—intellectual inferiors who whimpered out after our ultra-brainy species spread over the globe. Decades of scientific findings now exist to refute that notion, showing that Neanderthals were extraordinarily sophisticated—painting caves, lighting fires, even making use of medicinal plants. What snuffed them out wasn’t their lack of smarts but a lack of immunity to the (likely viral) diseases that Homo sapiens introduced to them as the two species mingled.
 
That same tragic motif plays out repeatedly over some 60,000 years, as Kennedy points to the cast of microbes that played startlingly prominent roles in several otherwise-familiar chapters of our history. Neolithic farmers may have edged out their hunter-gatherer predecessors with the help of hepatitis B, tuberculosis, measles, and a bevy of mosquito-borne viruses; diseases such as typhus and smallpox may have helped turn the tide against Athens in the Peloponnesian War. Spanish conquistadors appear to have been aided in their obliteration of the native populations by smallpox—an inadvertent weapon at least as powerful as any tool forged by hand. And although it’s clear that various sociopolitical factors were key to the ultimate founding of the United States, it’s also a bit fun to cheekily consider malaria-carrying mosquitoes as among the “founding mothers of the United States,” as the historian John McNeill once put it. The parasitic disease—which established itself in the American South prior to the Revolution—killed eight times more British troops than did American guns, potentially enough to substantially tilt the odds.
 
Other societal forces such as religion and politics have infectious roots too. Horrific bouts of plague, Kennedy writes, were major catalysts for the global spread of both Islam and Christianity—religions that were able to find massive audiences only after large sectors of the global population had died off, and survivors had begun to lose faith in the efficacy of local religious practices. Perhaps Christianity offered a more soothing balm for mortality than paganism at a time when painful deaths were terrifyingly common. And maybe “the lethal effects of Yersinia pestis,” the bacterial pathogen behind the plague, truly were what helped Islam develop into “a major religion practiced by almost a quarter of the world’s population.”
 
There was little awareness of the deus ex microbe as these events unfolded—which is understandable, given that it took until the end of the 19th century for germ theory to gain traction among leading scientists. But Kennedy makes a compelling case that historical ignorance has left behind some pretty sinister vestiges. Neanderthals, ravaged by disease, are still regularly cast in modern terms as dumb brutes; the native peoples of South America, technologically advanced but beaten down by foreign epidemics, imagined themselves disfavored in the eyes of the gods, who instead took the side of the colonizers who ravaged them with diseases.
 
Pathogenesis even implicates infectious disease in the reinforcement of—maybe even the genesis of—certain racial stereotypes. West Africans trafficked to the Americas initially labored alongside white slaves and indentured servants. But when diseases ferried over from Africa began to obliterate those lighter-skinned people, the darker-skinned people who’d already built up immunity were spared—leaving a population of almost entirely Black slaves. Abruptly, the region’s conceptions of slavery became linked to melanin, a stereotype that has insidiously stuck. It was a horrible irony: The movement of pathogens put a premium on protection against them—but ended up saddling survivors with horrific consequences. Our notion of superiority over certain groups, Kennedy suggests, is at least as misguided as our smugness about our supremacy as a species in this world.
 
Kennedy’s point isn’t that we’re powerless against infectious disease. (Nor are microbes unilateral villains: The opening to Pathogenesis painstakingly details the many ways in which the benign ones have benefited us—including aiding the evolution of the placenta, a vital mammalian organ that is thought to have co-opted genetic material from an ancient virus that infected our ancestors.) But, he suggests, humans will remain vulnerable to pathogens’ formidable powers if we continue to ignore them and not learn from the past responses of people in similar circumstances. The ongoing coronavirus pandemic, after all, is not the first time that people have concertedly pushed back against calls for face masks; nor is it the first time the public has bought into lethal misinformation. As Kennedy writes, the cholera outbreaks in 19th-century Europe sparked rumors that the public-health officials and doctors trying to enforce quarantines, travel restrictions, and isolation for the sick were a front—a plot to “poison the urban poor.” Locals rebelled, and governments capitulated, abandoning the very interventions that might have saved countless more lives.
 
Those missteps are important to keep in mind as we look ahead. Our modern habits are technologically advanced but epidemiologically dangerous. As the globe’s population has grown, infections have gotten easier to spread; as we’ve domesticated animals, we’ve carved new conduits for microbes to travel across species lines. Climate change is also pushing wild creatures into new habitats, where they’re more likely to encounter us. Disease spillovers into humans will keep happening; in just the past two decades, three have occurred with coronaviruses alone. That’s a grim fact to consider. And yet, Kennedy’s book manages to end on a somewhat hopeful note. Yes, our trajectory is defined by microbes. But it’s also influenced by our reactions to them—and our acknowledgment of their power. This current pandemic may be tilting toward a slow end. As much as we may want the crisis to disappear in the rearview, the coda of one outbreak is an ideal time to prepare for the next, inevitably on its way.

A History of Humanity in Which Humans Are Secondary.  A new book tells the story of our past from the perspective of the bugs that have shaped it. By Katherine J. Wu. The Atlantic, April 18, 2023. 

In the first chapter of Jonathan Kennedy’s Pathogenesis, he singles out Yuval Noah Harari’s Sapiens as a history that strays too far from scientific facts in service of a grand narrative. This is before Kennedy, a sociologist and lecturer in public health, has even begun constructing his own scientific-historical case: that germs — bacteria, viruses, and other communicable pathogens — have been a powerful and yet-unrecognised driver of human history. Later, he takes Jared Diamond’s Guns, Germs, and Steel to task for giving insufficient credit to the germ part of the triad — suggesting that “germs, germs, germs” is closer to the truth.
 
In an era in which authors tend to offer nothing but unreserved praise of each other via book cover blurbs, it’s refreshing to see a first-time writer take aim at what he sees as the failings of two of the best-read popular history titles of the past 30 years. It also draws the battle lines for Kennedy’s project. Germs, he contends, are a very big deal.
 
His basic thesis is that our intentions (or rather, those of any “great men” of history) mattered less than they or we ever thought. A true “history from deep below” should recognise, as he puts it, that “the modern world has been shaped by microbes as much as by women and men”. This isn’t an entirely new idea — many histories consider the powerful effects of disease — but the perspective is novel. To Kennedy, pathogens aren’t understood simply as catastrophes visiting destruction upon us but as complex living beings with their own history irrevocably intertwined with our own.
 
Kennedy argues this in chapters clustered roughly by era, where he revisits familiar events armed with a microscopic lens. He suggests that 8,000-9,000 years ago, as farming spread into Europe from what is now Turkey, hunter-gatherers weren’t supplanted via conquest or culture, but by farmers incubating novel diseases such as tuberculosis in their densely packed, settled communities. After centuries, farmers finally emerged with stable immunity — which their hunting and gathering cousins didn’t have once they began encountering those same diseases.
 
The book shines when it brings cutting-edge science to bear on these questions, something that Kennedy treats with great care. There are studies emerging that swab ancient tooth pulp and sequence the genes of bacterial fragments within them, showing which Neanderthal or homo sapiens ancestor died by which bug, where, and at what time. Like a map of temperatures or ancient waterways, we may come to see cycles of disease and immunity as equally strong shapers of early human settlement.
 
When the book fails, it is usually because the germ explanation becomes stale. Kennedy labours to prove that the bubonic plague, which probably arrived in Europe in the mid-1300s via Eurasian trade routes, is responsible for everything from capitalism, to Protestantism, to the modern university system. The death of more than 50mn people clearly threw the continent into turmoil, but extrapolating out from it in too many directions causes the book to lose its focus.
 
In the strongest sections, like those covering colonialism and slavery, germs feel powerfully alive and at work in history. Yellow fever and malaria kept colonisers out of much of Africa for centuries. But when mosquitoes carried yellow fever across the colonised Caribbean, and malaria to the American South in the 17th century, they disproportionately struck down the indentured European labourers. Plantations’ horrific embrace of African slave labour, Kennedy suggests, was partly a question of finding labourers immune to specific diseases. By mining the grim statistics of colonial bureaucracies, the book convincingly traces the ways cycles of disease and immunity shaped the outcomes of expeditions, trade, wars and ultimately entire civilisations.
 
Microbes existed well before humans. And their domain extends from parts of Earth we have never reached to the inside of our own bodies. Despite this, they often appear in circumscribed form in our histories — plagues arising and receding from some outside place, almost at random. Pathogenesis shows a microbial world that is as complex, dynamic, and alive as the human one, and just as consequential.
 
Pathogenesis — a history of microbes and men.  Jonathan Kennedy argues that germs have shaped our world more than humankind has — and it’s time we took notice. By Stephen Buranyi. Financial Times, April 12, 2023. 

On Tuesday afternoons, pathology teaching at medical school required me to peer down a microscope for two hours, screwing my inactive eye ever more tightly shut as if that would make the looking eye suddenly see clearly. Each eosin-stained slide with its pink and purple lines and splodges of diseased cells was as legible to me as a barcode. The tiny world beneath my lens created an illusion of human supremacy, a world where the truth was small, immobilised and bored of itself.
 
Pathogenesis – the cause of disease, its development and the impact it has on cells and organisms – is thankfully not what Pathogenesis is about. Jonathan Kennedy is a sociologist, not a microbiologist, and his unit of interest is the epidemic event, not the single bacterium. Where tales of great white men, great inventions and great power once populated the history books, Kennedy argues that great plagues are what really matter. Immunity has been the unifying asset of survivors and victors. The historical sweep of his pen could not be wider, from pre-history to post-Covid. Three hundred-odd pages roam through 50,000 years, and by the last it’s almost impossible to disagree that infectious diseases are our permanent companion and ultimate adversary.
 
Humans are not always in competition with pathogens, though. In fact our existence is indebted to them. A viral infection hundreds of millions of years ago might have enabled our brains to form memories, because of the insertion of a heritable piece of DNA that codes for ‘tiny protein bubbles’ to assist information transmission between neurons. Moreover, the fact that we’re not nibbling at the shells of our mothers’ eggs is because ‘a shrew-like creature developed the capacity to gestate her young inside her own body’. Thanks to a retrovirus, mammals were gifted the placenta and the relative safety of pregnancy.
 
As possibly the only person not to have read the 2014 mega-hit Sapiens, I was intrigued by the more speculative sections of deep history on different human species. For 250,000 years, Homo sapiens lived alongside other humans, including Homo erectus, Neanderthals and Denisovans. It was only 40,000 years ago that Homo sapiens spread across the world while fellow species became extinct. Emerging evidence suggests Homo sapiens in fact reproduced with other human species, and today approximately 2 per cent of our genes comes from Neanderthals. We know about these meet-cutes because of archaea found in calcified plaque on Neanderthal teeth, which could speculatively have been transmitted through kissing, and this same archaeon is a cause of modern gum disease. The evolutionary advantage of genetic mixing of the two species’ microorganisms gave Homo sapiens resistance to unfamiliar diseases and a lifeline for survival and dominance.
 
The fluency of Kennedy’s narration is remarkable, weaving Tolkien, Game of Thrones and Monty Python into memorable and accessible explanations of genetics, evolutionary biology and demography. Whether looking at hunter gatherers overwhelmed by new zoonotic diseases, Thucydides’ account of the Peloponnesian War and the role of plague in Sparta’s victory, or the 60 per cent decline in Europe’s population from 1348 due to the Black Death, each era in history seems to hinge on infectious disease as a ‘devastating weapon of mass destruction’. The result of recurrent infections and exterminations is that ‘contemporary Europeans are neither genetically “pure” nor are they the region’s indigenous people. Even white Europeans are mongrel immigrants.’
 
Events across the Atlantic further strengthen Kennedy’s point. When the Spanish arrived in the New World, their exposure to domesticated animals and denser populations back home gave them the upper hand in encounters with natives who didn’t enjoy such immunity. Kennedy perhaps oversimplifies this ‘virgin soil hypothesis’, as historians of medicine have emphasised the role of social factors and living standards too. But Old World pathogens did result in a 90 per cent fall in the population across the Americas, far outranking damage from imperial force. Smallpox, malaria, yellow fever and measles were the true, though unconscious, armamentarium of the colonisers. African immunity to malaria went on to fuel the racist ideology used to justify human trafficking across the Atlantic during the slave trade and became the foundation for economic arguments to exploit their labour.
 
Kennedy wears his politics on his sleeve, as well as his despondency. The idealism that inspired the WHO, established in 1948, was corroded when the US and UK in the 1980s, under Reagan and Thatcher, reduced their contributions to addressing the global burden of disease. Today, ‘vaccine colonialism’ means that antiretroviral drugs are stockpiled in wealthy nations, but are relatively scarce in poorer ones. Inequality also thrives at home, where a man’s life expectancy in Blackpool is 27 years less than a man living in Kensington and Chelsea – the same difference between the UK and the most deprived countries in Africa. However, the West’s big killers are cardiovascular disease, cancer and Type 2 diabetes. Although not transmitted like a virus, these noncommunicable conditions are socially contagious.
 
As impressive and enjoyable as Pathogenesis is, Kennedy openly concedes that his argument is not new. Historiographically, the idea of pathogenic supremacy has had several outings, most notably in William McNeill’s Plagues and Peoples (1976), which offered a radically novel interpretation of world history through the impact of disease. A new edition in the 1980s was prompted by Aids, just as Kennedy rightly justifies the need for his book with the impact of Covid, discoveries about the microbiome and the new technologies available for recovering the pathogenic signatures of the past. What is recurrently appealing and somewhat horrifying to new audiences about this strain of history is the way it destabilises human agency to such an extent that the purpose of our endeavours is thrown into question. If the bugs write the script, what chance do we have? A microbe-centric approach tends towards biological determinism and nihilism, carrying the risk, once again, of dismissing and underfunding the social determinants of health.
 
Ironically, we have reached the Anthropocene, when human action is finally changing the course of our planet’s history. Emissions in the atmosphere and the misuse of antibiotics have introduced the two urgent threats of global heating and antimicrobial resistance. The pair also interact. Warmer climates invite new pathogenic dangers, as anyone who has watched the trailer for HBO’s The Last of Us will know.
 
Small changes can lead to massive storms, but this could also be a reason for optimism. Pathogenesis might perhaps be read as an invitation to refocus on the minute particulars of our actions, and the billions of encounters between the human and natural world that occur every day. There is an opacity and unpredictability to both evolution and history that can never be fully recovered in our accounts of either. The famous Darwinian tree of descent, which Kennedy describes, is in fact more like a wild root system. As Deleuze and Guattari wrote in 1987: ‘We no longer follow models of arborescent descent going from the least to the most differentiated, but instead a rhizome.’ These tangled interactions show that while Pathogenesis is a humbling story for humankind, it is also one of radical contingency.
 
Great men don’t shape history – but tiny microbes do. By Kate Womerlsy. The Spectator, April 8, 2023. 

The Covid-19 pandemic has wreaked extraordinary destruction and misery, killing nearly 7 million people worldwide thus far and devastating the lives of many more. And yet, viewed through the long lens of human history, writes the public health sociologist Jonathan Kennedy, “there is little about it that is new or remarkable”. Previous pandemics have killed many more, both in absolute numbers and as proportions of populations, and so may future ones. Covid should be a wakeup call that helps us manage deadlier plagues in the future. But will we heed it?

 
Our very existence and success as a species, Kennedy argues in this fascinating book, has been shaped by bacteria and viruses. Where, for example, did all the other species of humans go? At one time, early Homo sapiens shared the Earth (and interbred with) the stronger, larger-brained and equally artistic Neanderthals, as well as the hobbit-like Denisovans. What happened to them? It could be, as some argue, that we simply killed them all, or that they were somehow less well able to adapt to climate change. But Kennedy explores the possibility that roving Homo sapiens from Africa, who had acquired strong immune systems on their travels, might have simply infected the already settled Neanderthals of Europe with a novel pathogen that they couldn’t fight off – just as the colonising Spanish, tens of thousands of years later, decimated the Aztec population with smallpox as much as with weapons.
 
A similar dynamic repeats itself over and over in human history, in Kennedy’s telling, even if some of the details remain speculative. Why, for example, were dark-skinned Neolithic hunter-gatherers such as the celebrated “Cheddar Man”, who first settled the British Isles after the last ice age, replaced throughout Europe by light-skinned farmers of Mediterranean origin? “The most likely answer,” the author suggests, is that the farmers carried infectious diseases to which they had, over time, become immune, but which devastated the indigenous populations. Those farmers were in turn almost completely replaced by another wave of migrants, shepherds from the Eurasian steppe – thanks, perhaps, to a Neolithic wave of bubonic plague in Europe. Kennedy does not shy away from emphasising the point most relevant to modern politics: “Contemporary Europeans are neither genetically ‘pure’ nor are they the region’s indigenous people.” Modern genetic analysis shows that even the people who built Stonehenge were completely wiped out and replaced by a new wave of migration. As Spinal Tap so clairvoyantly put it: “The druids. No one knows who they were, or what they were doing.”
 
We can be more confident, at least, about the geopolitical effects of disease once we enter the era of written history. An epidemic of either typhus or smallpox devastated Athens from BC430, which “undermined Athens’s capacity to fight against the Spartans and had a profound impact on the course and outcome of the Peloponnesian War”. A series of plagues beginning in 65AD, meanwhile, might have weakened the Roman empire to an extent that contributed to its eventual fall. Medieval waves of the Black Death, it is salutary to be reminded, killed astonishing numbers of people – as much as 60% of the entire population of Europe succumbed in a single decade of the 14th century.
 
The subsequent introduction of rules of quarantine and cordons sanitaires, Kennedy argues, can be seen as marking the beginnings of the modern state, extending as they did its power into ordinary human life in unprecedented ways. Meanwhile, the shortage of agricultural labour caused by devastating recurrences of the plague was perhaps instrumental in the collapse of feudalism in favour of a capitalist system of flexible employment. Later on, the susceptibility to malaria of northern soldiers in the American civil war “probably delayed victory by months or even years”, possibly giving Lincoln time to come round to the idea of abolishing slavery.
 
The book thus performs that satisfying trick of encouraging the reader to think differently about familiar topics, though its ideas are inevitably variable in their persuasiveness. Among the most conjectural, for example, is the suggestion that the rise of Christianity in the imperial Roman era might itself have depended on the prevalence of disease, because of its consoling message. “The Christian faith skyrocketed because it provided a more appealing and assuring guide to life and death than paganism during the devastating pandemics that struck the Roman empire in the second and third centuries CE,” Kennedy suggests. Well, maybe. But the conversion of Constantine, briefly mentioned on the same page, was surely the nearer and sufficient cause.
 
There is, too, occasionally a slightly po-faced attitude to Kennedy’s discussions, as when he cites the “What have the Romans ever done for us riff” from Life of Brian. (There is “something unsettling about a group of white, Oxford- and Cambridge-educated men extolling the virtues of colonialism, albeit for comedic effect,” he complains piously.) And the depredations of “capitalism” come to figure, in this story, as a villain as evil as any virus. The economic growth driven by the Industrial Revolution, Kennedy claims, did not, as is usually thought, increase welfare through improved living standards, though here his disagreement seems to be merely about timescales. (It didn’t overall at first because many of the new cities and working environments were filthy and unsanitary, but it sure did in the long run.)
 
The author seems to approve considerably more of capitalism with Chinese characteristics, celebrating the undoubted improvement in living standards of many millions of people in China over the last few decades. He is also curiously happy to accept the official Chinese figures on Covid death rates in order to argue that the US and “liberal democracy” in general are not obviously superior systems.
 
Kennedy is convincing, though, in his emphasis on the way that disease can intersect and interact with social inequality, both globally – most sub-Saharan Africans remain unvaccinated for Sars-Cov-2, the rich countries having kept multiple doses for their own citizens – and within countries, where health outcomes are shockingly dependent on socioeconomic status. What is sometimes called “shit life syndrome” will harm you as surely as many infectious diseases, and “pathogens thrive on inequality and injustice”.
 
So what will we do now? Perhaps, as Kennedy suggests, the recent, comparatively mild pandemic will cause us to rethink “how humans see their place in the world”, to stop creating super-pathogens with our incontinent use of antibiotics, and to realise that “if we Homo sapiens don’t strive to live in balance with the other living things on our planet, we face a very bleak future”. That, however, is a tall order, and not just politically. Bacteria alone make up an estimated 13% of the biomass of Earth, while humans represent a mere 0.01%. In the war against disease, we are massively outnumbered.
 
Pathogenesis by Jonathan Kennedy review – in sickness and in health. By Steven Poole. The Guardian, April 6, 2023.