An international team of scientists led by the Max Planck Institute for the Science of Human History has discovered the first direct genetic evidence of the Plague of Justinian in the British Isles from the Anglo-Saxon site of Edix Hill, in southern Cambridgeshire. The Plague of Justinian is believed by many researchers to have been one of the primary causes of the fall of the Roman Empire but until this point it was unknown in the British Isles. As such, these remains may give us new insight into the disease that helped to bring down one of the greatest empires history has ever seen and solve one of history’s greatest mysteries.

In the middle of the second century A.D. the Romans were the preeminent power in the world. The empire spread from northern Britain, in the west, to the Sahara, in the south. Five centuries later much of that empire had been eroded or collapsed. It had become, in the words of Kyle Harper, “a small Byzantine rump-state.” To be sure, Rome had suffered military losses including several devastating ‘sackings’ of Rome, but these alone cannot account for Rome’s demise. How did this transformation—which has sometimes been called the biggest setback in the history of human civilization—happen?

A spate of recently published academic and crossover trade books, most recently Harper’s The Fate of Rome: Climate, Disease and the End of an Empire, have argued that climate change and environmental agents were the ultimate reason for the Fall of the Roman Empire. Two environmental factors are now cited as the main causes for the fall of Rome. The first is the already mentioned Justinian plague, a pandemic of bubonic plague that reached the Roman Empire around 541 and would sporadically reappear throughout the region for the next two centuries. The plague features prominently in several modern histories of the fall of empire is known to us from sixth century writers such as the Byzantine historian Procopius and the Syriac Church historian John of Ephesus. They describe an illness that caused fevers, swollen buboes, and hallucinations. DNA analysis of sixth century skeletal remains has revealed that the disease was bubonic plague. Harper has estimated that mortality rates during the first pandemic were as high as 50-60 percent of the total population of the Empire. The medievalist Lester Little, editor of Plague and the End of Antiquity, wrote that the plague helped “usher in the Middle Ages.”

The second is a cluster of environmental changes that includes the so-called Dust Veil event (or perhaps disaster, but it’s mainly known as “the Dust Veil Event”), which took place in 535-36 and was caused by volcanic eruptions, and was followed by the so-called “Late Antique Little Ice Age,” a period of cooling in the sixth and seventh centuries. According to Procopius, “during [535-46 A.D.] a most dread portent took…the sun gave forth its light without brightness ... and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.” Evidence from elsewhere around the globe suggests that something “big” happened in this period. A dense fog was seen in China and Europe. There was a drought in Peru; and snow fell during summer months in China. The Irish Annals also refer to crop failures.

Scientific analysis of tree rings by Mike Baillie, a scientist at the Queen’s University in Belfast, revealed that there was very little growth in Irish oaks in 536 (with a second drop in 542). Independent ice core analysis from Greenland and Antarctica uncovered substantial deposits of sulfates in 534 (give or take two years), which is suggestive of acidic dust in the atmosphere. These eruptions were followed, according to scientist Ulf Büntgen, by LALIA, a period of cooler temperatures across Europe that lasted from 536 to 660.

What’s fascinating about this work is the way that it opens up the possibility of truly interdisciplinary work among scientists and historians. The recent article in PNAS was co-authored by renowned historian Michael McCormick. The work of Harper, McCormick, Little and others should be commended for taking environmental factors seriously. Many of the peer-reviewed publications that have come out of this area of inquiry have featured clusters of authors drawn from both history and the hard sciences. At the same time, this new and exciting approach needs some serious tweaking.

A recently published article in the Journal of Late Antiquity by historian Kristina Sessa, a professor at the Ohio State University, has drawn attention to some of the problems that underpin this kind of research. The first is the use of proxy evidence to measure environmental changes, that is evidence that was culled from an adjacent (or sometimes not-that-adjacent) time period or geographical region because evidence for that particular time and place does not exist or cannot be accessed today. Given how regional and particular weather patterns are, for example, is tree ring analysis from central Europe and southeastern Russia universally applicable to the ancient Mediterranean?

Sometimes general trends, she shows, while true, don’t accurately describe local phenomena. Thus while it is possible to say that the sixth and seventh centuries A.D. were colder and wetter than the centuries that preceded them, when archaeologist Paula Kouki went to look at how ancient settlement patterns in Jordan are tied to weather patterns she found that favorable weather does not always correlate to flourishing communities. Kouki was looking at the sixth and seventh centuries, the very period during which “decline” is supposed to set in, but the results of her research did not match widely held assumptions about climate change and resettlement. As Sessa puts it “when we move from the macro- to the micro-regional level, it is clear that climactic and human activity often bear little causal relationship to each other.”

As for the evidence of the plague, Sessa cautions about drawing grand conclusions about the deaths of tens of millions from limited archaeological evidence. She highlights that at the time of her article going to press we possessed the physical remains “of precisely ten people whom we know died of plague in the sixth century” and those bodies are from remote parts of the Roman empire. Of course, as Harper has observed, this could serve as evidence of the rampant and extensive spread of the plague. On the other hand, and even granting the recent discovery of the first genetic evidence of the Justinianic plague in the British Isles, our evidence is somewhat limited (the new study brings the total number of remains to 30).

For geneticists, who care about the evidence for the genome, the number of bodies doesn’t really matter. But for historians, who want to know how many people died, it’s of pressing concern. Statements about how many people died rely on models for the spread of plague that come from periods when the population density was different. Given how central population density is to the spread of disease (i.e. the more closely people live to one another, the more contagion, and, thus, the faster the spread of the disease) this should give us some cause for concern.

Things aren’t easier when we turn from the scientific to the literary evidence. Some have claimed that the apocalyptic worldview and concern for the end of the world that we find in the writings of late antique Christian writers is evidence of the effects of the plague on ancient peoples. With death literally at the door, the argument goes, Christians began to think of the world as the arena for a battle between good and evil.

The problem with this argument is that it ignores the widespread Christian interest in the end of the world that predated the plague of Justinian. At risk of making early and late antique Christians sound like a bunch of drama queens, most early Christian literature was apocalyptic and contained at least a nugget of interest in the end of the world, its aftermath—and the competing cosmic forces inhabiting the world in the present. Despite what scholars have sometimes thought, Christians don’t need political or environmental reasons to be interested in the apocalypse and apocalyptic thought. It’s an important way of thinking and writing that does important theological work outside of periods of crisis.

Perhaps the biggest issue is tracing the fall of the entire empire to a single chain of non-human environmental events. While recent studies like Harper’s are careful not to do this, some have traced everything from the rise of Christianity to the fall of the Roman empire back to a single set of volcanic events. It surely is more complicated than this.

Did the plague contribute to shifts in socio-political arena in the sixth century? Absolutely, but not in a vacuum. One of the strangest things about crediting climate change with the fall of the Roman empire is the way in which it strips events of human agents. Sessa told The Daily Beast “one of the other curious things about all of this ‘environmental fall of Rome’ scholarship is that, with all its emphasis on material agency, it has pivoted so far from an anthropogenic interpretation of climate change that human agency is left as something of an afterthought… Volcanoes, microbes, God—indeed everything seems to be behind environmental crisis in the Late Roman Empire but the Romans themselves.”

Perhaps the more pressing question is why are people so obsessed with what Edward Gibbon called The Decline and Fall of the Roman Empire. When it comes to the disappearance and collapse of past civilizations, no empire captivates audiences as much as that of the Romans. Perhaps it is because so much Western European and North American bureaucratic architecture is modeled on ancient Roman building projects; that the United States borrowed the eagle from Roman propaganda; or that the Founding Fathers and Western educational ideologies so often hark back to the supposed glory days of Rome when talking about their own ideals and identity.

In many ways the reason that environmental theories for the fall of Rome have captured the attention of popular news outlets in the 21 st century is because of the ways in which Rome and climate change resonate in our own day. Climate change figures highly on the political agenda (full disclosure: I think it should) and our cultural obsession with identifying ourselves with the Romans means that it is possible to leverage the past to make political claims about the present. The problem is that this trick is used by everyone: as historian Andrew Gillet has shown, the conservative right likes to use the “barbarian invasions” that sacked Rome as prefigurations about the dangers of immigration. As Sessa put it, “The fact that neo-conservatives such as Niall Ferguson have invoked Rome’s fall to warn western society to fear immigrants and a multicultural society lest they wind up like the Romans should give us pause in using the narrative.” Sadly, for each of us, the appropriation of history and its “lessons” is not limited only to those with whom we agree; it’s part of a trend that’s as self-absorbed as it is powerful.