Having your research written about in Science or Nature, or getting your article published in one of these journals (and PNAS) is one of the highlights of a scientist’s career. Competition is pretty fierce, and the editors of these prestigious journals tend to behave in a pretty high-handed manner. Although we complain about it among ourselves, we play the game, because potential rewards are worth it. Much of it is pure status competition, but publishing a paper in Science or Nature practically guarantees that it will have high impact, and not just on the scientific community.
I don’t have hard numbers, but my impression is that if you want to publish a paper on the evolution of complex societies in Science, your best bet is to first get trained as a climatologist. Somehow the combination of civilizational rise or collapse (a deservedly newsworthy topic) and ‘hard science,’ represented by climatology, proves irresistible to Science editors.
One recent example is a News Focus article “Roots of Empire: A climate history project in Mongolia is charting the unexpected conditions that may have propelled the rise of Genghis Khan” which was published in the September 28 issue of Science. Among other things the article claims that “the relationship between climate and the decline or collapse of civilizations is well established.” But its main focus is the claim that the rise of the Mongolian Empire under Chinggis (a more accurate spelling of his name) was due to a period of unusually good climate between 1211 and 1230.
The Mongol army (source)
Although I am very much in favor of reconstructing past climate and analyzing its effect on historical dynamics (more on this in the next post), I am very skeptical of current claims that purportedly establish a direct relationship between climate and the rise or collapse of civilizations. It is quite likely that climate change is one of the secondary factors affecting history, but a prime mover?
Despite its trappings of ‘hard science’ current research on the influences of climate on history lavishes all scientific rigor on the first part of the job, reconstructing past climates, and then turns ‘soft’ when it gets to the climate impact on historical societies.
As an example, there was another recent paper in Science (4 February 2011, this one a research article), “2500 Years of European Climate Variability and Human Susceptibility.” Here’s what the authors did when they got to the effect of climate on history:
Apparently the only approach used by the authors was to eyeball the graph and connect it to various historical events (I did not check the Supplementary Materials, perhaps they present a statistical analysis there?). You give me any series of random numbers, and I can guarantee you that I will come up with a neat story about how it explains history.
This reminds me of an anecdote, apparently told about some famous physicist. As he was talking to a colleague, a student rushed up to him with a graph depicting the latest experimental results. The famous physicist looked at the graph and said:
“Of course, it makes perfect sense. This is precisely what the theory predicts.”And then proceeded to explain how.
“Professor, you are holding the graph upside down…”
“Oh…[turning it right side up], but of course, it makes perfect sense – this is precisely what the theory predicts!”
And this is how much of current research on climate and history looks to me.
Returning to the case of the Mongol conquest, sudden eruptions of steppe nomads have often been explained by poor rainfall in the steppe. Faced with the prospect of starvation on the steppe, the nomads instead choose to attack the nearby farming societies. As the Science article mentions, Arnold Toynbee was one of the proponents of this theory.
It is very likely that this mechanism was at the root of the intractable conflict in Darfur. As the climate got drier during the last two decades the pastoralists, who had raised livestock in the plains of Darfur, started migrating towards the hilly region, which always got more rain and was where agricultural communities lived. This resulted in conflict between farmers and nomads. Nomads then created an alliance against the farmers (this is the origin of the infamous Janjaweed) and raided villages, while farmers created their own defensive alliance and allied with the SPLA. The tragic results (but not the causes of the conflict) have been amply covered by the media.
Once again returning to Mongolia, we learn, however, that lack of rain was not a problem during the Mongol eruption under Chinggis Khan in early thirteenth century. In fact, the opposite was true. Apparently, abundant rainfall was good because it increased the productive base of the nomad society and made their military conquests more possible.
So far so good, but when the period of abundant rainfall ended around 1258, the Mongolian empire did not collapse; in fact it continued to expand. As one of the researchers quoted in the article says, the Mongols did not collapse, “they restructured.”
OK, I believe I made my point. But to end on a positive note: I think that what the climatologists cited in the article do is great. I can’t wait until they publish the data they are currently collecting. And then we will need to do a much better job determining how climate affects human history. I’ll discuss this question in the next blog.