Note the following blog was written before I knew about the research highlighted in another blog: see "Did rats spread the black death?" Anyway, with that caveat, you can still read my wiki thoughts on the plague, starting now…
I recently saw a serial called Spiral on Netflicks (an engaging crime drama set in France) wherein one of the episodes a judge intoned something to the effect that the lesser of two evils was itself still quite an evil. Loosely translated the statement was “it’s cholera or it’s the plague”. It got me doing a sort of imagining what it must have been like to live during one of the outbreaks of bubonic plague in Europe, while at the same time tasking by queuing up the next episode of Spiral (this episode featuring a cop with a drug addiction). To help with the former, I turned to the digital milieu of Wikipedia.
We often wonder how strongly selection from disease is ‘shaping’ us humans. By shaping: I do not mean in an individual sense like the cop’s struggle with drugs, but in the sense of a population, or a collection of populations. Conditions like sickle cell anemia, human blood groups, and cystic fibrosis might have been selected in the past by infectious diseases like malaria, cholera, or the plagues. In fact, the link between heterozygotes with one copy of the sickle cell allele and resistance to malaria is well established. Other proposed linkages are rich hypotheses deserving of much attention: strong treatments of such ideas will likely lie in contributions from history, modern epidemiology, and molecular biology (or its outgrowths of functional genomics and proteomics).
I still wonder though what it would have it been like to live during a pandemic of a virulent pathogen? I suspect it would have been a time of abject fear. I think Albrecht Dürer had it right in his rendition of the four horsemen of the apocalypse. Plague was riding in, neck and neck with war, followed by famine, and upstarted by skeletal death. There would not have been much room for hope. Yet many survived the plague and its variations with variations of their own, following from which selection had acted.
Continuing with wikipedia insights, the black plague, caused by the bacterium Yersinis pestis, was thought to claim the lives of tens of millions (upwards of 200 million) in Europe, in the 14th century alone. This bacterium is vectored by a rodent flea, whose gut is so distended by bacterial films that it regurgitates bacteria into the wound it creates when feeding on humans. There are so many questions worth asking, like how many plagues were there?, how virulent were the different plagues to humans?, how many species of rat fleas carry Yersinis? , and, how much is known about how the disease manifests itself in rats, if at all? One has to go far beyond Wikipedia distillations (which are sometimes wrong) to vet and test some of these questions.
But it is still of interest to see where Wikipedia takes you. When one hyperlinks further, one begins to see unlikely coincidences. Consider Sir Isaac Newton and his being forced to take a sabbatical during Cambridge University’s closure during the 1665-1666 Great Plague of London. During that outbreak, an estimated 15% (or 100,000) of London’s population died. During that 18-month period at his estate, Sir Isaac Newton was purported to have investigated the nature of light, write on the laws of motion and draft the universal law of gravitation, as well as put together a treatise on Calculus. Modern academics often decry that time is in such short supply but even with 18-month sabbaticals, doubtless even another rare mind would achieve what Newton did. As one of many stories go, Newton got his inspiration for the Universal law of gravitation by watching an apple fall from the tree. A serendipitous moment. But one has to ask: what was Sir Isaac doing in the orchard in the first place? That had more to do with bacteria in a flea’s gut. Or at least, that’s what the wiki tells us.
Professor & student