Saturday, July 11, 2015

Multi system failure

EricCline has a book about the Bronze age collapse, which he attributes to multiple problems (climate change, migration, earthquakes, war, famine). The only major empire that didn't collapse then was Egypt, but Ramses III managed to fight off the sea peoples (but was killed by a harem conspiracy, probably because he was so busy fighting he didn't notice people starving).

Another period of collapse was the destruction of Ghengis Khan, the climate cooling causing famines, and then the Black Plague came in. Again, lots of death and collapse (mainly of Islamic civilizations).

But before this, there was another "year without a summer", with starvation followed by bubonic plague.

but only recently have historians try to put two and two together via ice cores.


The team drew connections between the ice core evidence and historical texts describing diminished sunlight over long periods of time. The analysis revealed that there had been a massive eruption in North America in 535 or 536, followed by another in the tropics in 539 or 540 -- corresponding to temperature dips in the tree ring records starting in 536.
Of that year, the study noted, the historian Procopius had written, "For the sun gave forth its light without brightness, like the moon, during this whole year, and it seemed exceedingly like the sun in eclipse."
The authors wrote that the cooling, which extended for more than a decade, "provides a notable environmental context to widespread famine and the great Justinian Plague of 541-543 CE that was responsible for decimating populations in the Mediterranean and potentially China."
The Chinese histories need to be checked for such information, the problem being that a lot of times the bad news was not written down (and of course, losing hundreds of thousands of peasants wasn't such a big deal for some emperors, at least until the peasants had enough and decide to mount an uprising. You think Western European history is bloody, you need to do a body count of China).


related item: remember all those headlines about how many people were descended from Genghis Khan? Well they were wrong. Statistically it was a coincidence.

Forwhat...we are blog notes:

the authors, to make their argument even more certain, simulated genetic data under the standard coalescent, a neutral model that does not include cultural transmission of reproductive success. As you can expect, the simulations confirmed that what surprised Balaresque and others is just absolutely normal by mere chance: no Genghis Khan effect ever took place.

blame Zipf's law 

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