ils wrote:Salmoneus wrote:So a megademic would have be be both contagious and dangerous.
Smallpox and other Old World diseases are believed to have consistently wiped out 90-95% of the New World native populations they came in contact with, which I suspect is the model Tom had in mind. Diseases jumping into a population with no prior exposure may be nonlethal in their original setting but spectacularly lethal in the new one.
Of course, to achieve that lethality, a whole suite of pests and diseases would have to jump between species, which is a far taller proposition than their making the jump between previously isolated populations of the same species.
Ohh.... burpledom. I forgot about that. Still, I'll mention in my defence:
a) it wasn't just one disease it was lots. We thankfully didn't have smallpox AND measles appear at the same time in the old world, nor typhus with them. As you say, three megadiseases jumping the barrier at the same time is rather less likely..
b) the 95% figure is debateable anyway. the records can be massaged one way or the other
c) it's not necessarily the case that all of those disease deaths at about that time are due to Europeans. For instance, the obliteration of the Inca is traditionally ascribed to smallpox, but I'm told that some experts now believe the culprit was really Oroya Fever, native to the continent (it may have been the first epidemic of it).
d) destruction of existing political structures generally causes huge death tolls anyway, from starvation and assorted diseases, even without the 'new disease' element.
Tom, two questions:
a) Are you sure it started with African gerbils? I thought it was endemic to black rats, and didn't reach Africa?
b) I'm ignorant. Is there any evidence the Black Death was actually bubonic plague? Wherever I look, there's a small section "some people now think..."; that section then contains arguments that blow the plague theory out of the water, but the only pro-plague argument given is "this is not accepted by the majority of experts". Surely there must be SOME reason?
Off-hand, I've seen the following arguments against the European black death being the plague:
1.) the worst ever recorded death toll from the plague was 3% of a community. the Black Death reached over 75%
2.) the plague is carried by rats, and hence, even with motorised transport, travels slowly - almost alway around 10-15km per year. The BD travelled hundreds of miles a year, as though it were a virus.
3.) BD victims didn't usually have the key symptom of BP - the buboes, grossly swollen lymph glands. Instead, they had a different symptom - black sores all over the body, as though it were a haemorrhagic virus. (Black Pox can have similar, iirc, for example).
4.) Rat extermination programmes did not halt the BD.
5.) Segregation of infected personages and communities did halt the BD. Classically, the village of Eyam voluntarily closed itself to the outside world. The surrounding villages remained BD-free - but if it were rat-borne, then stopping human travel would not have had any effect, as the rats would ignore the blockades.
6.) there's no evidence, other than the BD, that the black rat was ever native to Europe (at least in large numbers)
7.) the BD spread to Iceland and northern Norway, where even today there are no rat populations other than in cities, and where at the time there were no cities. Specifically, in Iceland, which was very badly hit (as one would expect it to be, being a small closed community, IF it were a human-to-human virus), it is known that until recently there were absolutely no rats at all - so the plague would have had to have killed 100% of the rat population.
8.) The plague did not kill off even a significant proportion of the black rat population anywhere else in the world that had the plague - eg China and India still have both plague and black rats. If black rats were in Europe, then their supplantion by brown rats at the end of the plague would have to be coincidence.
9.) The BD spread to Iceland - a sea voyage of at least fourty days. A long time for a terribly sick rat to survive the plague, in very sub-optimal conditions (we're not talking great grain-galleons on the route from orkney to iceland). A longer time for no-one on the ship to develop symptoms that would stop the Icelanders from allowing them to land.
10.) BD survivors were far more likely to have specific gene mutation. This we know. We know that that mutation gives resistence to certain viruses - most famously HIV (10% of Europeans are HIV-resistent thanks to the BD). If it were the BP, it would be odd that Indians and Chinese did not get selected for the gene the same way Europeans did - if Europe had a different disease, though, it would be natural. If the BD were caused by Yersinia bacteria (the plague), there would be no reason why people with a mutation that helps resist viruses but not bacteria would do better at surviving than the general population. Additionally, we have observed selection for exactly the same gene mutation in several modern cases - specifically, where populations are ravaged by either HIV or a haemorrhagic virus (chiefly Ebola and Marburg). As it's unlikely it was Ebola in Eyam....
Anyway, the theory is that there were two diseases. One, in China and India, and still lingering, and which reached, quite slowly but aided by the Mongols, across Asia to the mediterranean coast - and this was plague. The other that occured chiefly in Europe, and that recurred several times before disappearing, probably being some kind of haemorrhagic virus, possibly related to Ebola - and this spread very rapidly from person to person.
Now, I know this isn't the majority view. But I can't find any defence of the majority view... anyone help?
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