Disease Helped Collapse Rome By Brian Simpson

     Here is an interesting article about the role of disease in collapsing Rome. Unfortunately, there’s a bit on climate change, but we need not get too scared, since we can admit that in the past climate change did occur, having both good and bad effects, with the Vikings in Greenland probably getting wiped out because of a colder, not warmer climate.
  https://www.sciencemag.org/news/2016/11/why-did-greenland-s-vikings-disappear 
  https://mercatornet.com/how-disease-and-climate-change-helped-the-fall-of-the-roman-empire/62972/

“At some time or another, every historian of Rome has been asked to say where we are, today, on Rome’s cycle of decline. Historians might squirm at such attempts to use the past but, even if history does not repeat itself, nor come packaged into moral lessons, it can deepen our sense of what it means to be human and how fragile our societies are. In the middle of the second century, the Romans controlled a huge, geographically diverse part of the globe, from northern Britain to the edges of the Sahara, from the Atlantic to Mesopotamia. The generally prosperous population peaked at 75 million. Eventually, all free inhabitants of the empire came to enjoy the rights of Roman citizenship. Little wonder that the 18th-century English historian Edward Gibbon judged this age the ‘most happy’ in the history of our species – yet today we are more likely to see the advance of Roman civilisation as unwittingly planting the seeds of its own demise. Five centuries later, the Roman empire was a small Byzantine rump-state controlled from Constantinople, its near-eastern provinces lost to Islamic invasions, its western lands covered by a patchwork of Germanic kingdoms. Trade receded, cities shrank, and technological advance halted. Despite the cultural vitality and spiritual legacy of these centuries, this period was marked by a declining population, political fragmentation, and lower levels of material complexity. When the historian Ian Morris at Stanford University created a universal social-development index, the fall of Rome emerged as the greatest setback in the history of human civilisation. … The highly urbanised, highly interconnected Roman empire was a boon to its microbial inhabitants. Humble gastro-enteric diseases such as Shigellosis and paratyphoid fevers spread via contamination of food and water, and flourished in densely packed cities. Where swamps were drained and highways laid, the potential of malaria was unlocked in its worst form – Plasmodium falciparum – a deadly mosquito-borne protozoon. The Romans also connected societies by land and by sea as never before, with the unintended consequence that germs moved as never before, too. Slow killers such as tuberculosis and leprosy enjoyed a heyday in the web of interconnected cities fostered by Roman development.

However, the decisive factor in Rome’s biological history was the arrival of new germs capable of causing pandemic events. The empire was rocked by three such intercontinental disease events. The Antonine plague coincided with the end of the optimal climate regime, and was probably the global debut of the smallpox virus. The empire recovered, but never regained its previous commanding dominance. Then, in the mid-third century, a mysterious affliction of unknown origin called the Plague of Cyprian sent the empire into a tailspin. Though it rebounded, the empire was profoundly altered – with a new kind of emperor, a new kind of money, a new kind of society, and soon a new religion known as Christianity. Most dramatically, in the sixth century a resurgent empire led by Justinian faced a pandemic of bubonic plague, a prelude to the medieval Black Death. The toll was unfathomable – maybe half the population was felled. The plague of Justinian is a case study in the extraordinarily complex relationship between human and natural systems. The culprit, the Yersinia pestis bacterium, is not a particularly ancient nemesis; evolving just 4,000 years ago, almost certainly in central Asia, it was an evolutionary newborn when it caused the first plague pandemic. The disease is permanently present in colonies of social, burrowing rodents such as marmots or gerbils. However, the historic plague pandemics were colossal accidents, spillover events involving at least five different species: the bacterium, the reservoir rodent, the amplification host (the black rat, which lives close to humans), the fleas that spread the germ, and the people caught in the crossfire. Genetic evidence suggests that the strain of Yersinia pestis that generated the plague of Justinian originated somewhere near western China. It first appeared on the southern shores of the Mediterranean and, in all likelihood, was smuggled in along the southern, seaborne trading networks that carried silk and spices to Roman consumers. It was an accident of early globalisation. Once the germ reached the seething colonies of commensal rodents, fattened on the empire’s giant stores of grain, the mortality was unstoppable.

     In the present political debate about Covid-19, which probably was cooked up in the Wuhan lab, we should not forget that there is still natural evolution of viruses and nothing prevents even next week, a real killer to emerge and enjoy the insane fruiter of a globalised world. We have already had a dummy run of what things could be like:
  https://www.cidrap.umn.edu/news-perspective/2007/02/severe-pandemic-not-overdue-its-not-when-if
  https://edition.cnn.com/2017/04/03/health/pandemic-risk-virus-bacteria/index.html
  https://www.washingtonpost.com/opinions/more-pandemics-are-inevitable-and-we-have-to-prepare-for-them/2016/01/21/0a77d3f8-bb0f-11e5-829c-26ffb874a18d_story.html