Professor Pangloss, meet Dr. Doom

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The most important thing about prediction is the time scale over which you are measuring. The probability of the extremely rare event rises to certainty with the passage of time. For example, the history of the earth for the last two million years shows that the next ice age cannot be further away than two to five thousand years. If we extend the time scale to several tens of millions of years, it is likely that the earth will pass through epochs considerably warmer than we are in now.

So it is with historical timespans, which are far shorter . The human race has been undergoing a massive population expansion since 1800 because of science, increasing energy resources, and a feedback loop between increasing wealth and increasing resources to deal with disease.

Yet the very forces that have created the population explosion are everywhere reducing human birthrates. Why? Because as women become certain of the survival of their babies, they have fewer of them. Just as the burden of humans on the planet reaches a peak, the human species declines in numbers. These are demographic certainties: the dearth of children since the 1970s has been felt in every part of the world, including especially the Islamic parts. Within three generations human fertility has crashed from 6-8 live births to about 2 live births per woman. Read David Goldman’s It’s not the End of the World, it’s just the End of You: the Great Extinction of Nations.

It was with interest and pleasure that I have been absorbing Kyle Harper’s The Fate of Rome. Harper is the first historian of whom I am aware to have taken seriously the impacts of disease and climate change on the fate of the Roman Empire. He addresses the reader’s attention to the startling scale of death in the three waves of pestilence that not just decimated, but halved, Roman populations in the period 200AD to 550 AD. There were three near-global epidemics that swept through the Empire, each assisted by the ubiquity of trade links and safety of travel that imperial security allowed. One was probably the first exposure of humans to what we later called smallpox. The second was an Ebola-like hemorrhagic fever.¬†

The third, which swept through the Empire when the Emperor Justinian was trying to restore civil order and prosperity in the mid-500s, was bubonic plague, which broke out in AD 542. The population of the eastern (Byzantine) Roman Empire fell by half in one year, from 30 to 15 million, and kept on falling for several decades after as plague returned. Imagine the stink of corpses when everyone is dying and not enough people are available to bury them.

Coupled with volcanic outbursts that clouded the sun, and variations in the rainfall in central Asia, which sent the Huns westward in search pasturage, causing them to crash into the Goths who crashed into the Roman Empire, these waves of disease, worsening climate, and barbarian invasions had utterly wrecked the western Roman Empire by AD 400. Brian Fagan records in his book, The Long Summer, that the cultivation of the grape and the olive used to take place as far north in Gaul as the current French-Belgian border, but that, after the Roman Climate Optimum suddenly collapsed around 400 AD, the olive tree grows no further north than its current line in France’s Massif Central. Can you imagine what it would do to US agriculture if the climate of Saskatchewan moved south 400 miles? In the space of ten years?

Compared to scientifically literate histories like The Fate of Rome, Edward Gibbon’s attempt to blame the fall of Rome on the rise of Christianity, the personalities of Emperors, and barbarian invasions, seems more like an exercise in oratory and Latinate English than anything accurate.

Which brings me to the genial, clever Professor Steven Pinker and his Enlightenment Now. Pinker presents the best case possible that progress in the past several centuries has been real, and that catastrophists are wrong. I have every reason to believe this story; I am a rational optimist myself. Pinker and his teammate, Matt Ridley, both make the irrebuttable case that the world has been getting massively better for all. I wish there were more people who were aware of how much and how rapidly human life has improved since 1800, since 1900, since 2000. In that sense it is important to point out how much I agree with Pinker.

And yet, the pace of evolution is accelerating as population becomes denser. The pathogens that struck down the Roman Empire in repeated waves are entirely recent mutations.

As Harper explains:

The last few thousand years have been the platform for a new age of roiling evolutionary¬† ferment among pathogenic microbes. The Roman Empire was caught in the the turbulence of this great acceleration….

The primacy of the natural environment in the fate of this civilization draws us closer to the Romans, huddled together to cheer the ancient spectacles and unsuspecting of the next chapter, in ways we might not have imagined.

We are as grass, and while the arguments for impending catastrophe are much weaker than supposed, it is unwise to think that all will be well. The influenza epidemic of 1918 killed 3 to 5% of the world’s population, 50 to 100 million people, more than the World War that preceded it.

Civilizations and empires can end because of diseases and climate change. They have already done so several times. There is no reason to suppose we are immune, notwithstanding the cheerful and truthful news from the likes of Steve Pinker and Matt Ridley.

Professor Pangloss, meet Doctor Doom.

 

The y-axis indicates deaths per thousand

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