Saturday, September 19, 2009

Jared Diamond's Psychohistory of the Human Race

In his Foundation Trilogy, Isaac Asimov describes a new kind of science: "psychohistory". The idea of this discipline is to predict the course of human history through mathematical analysis. The fundamental assumption is that the impact of individuals is "washed out" due to the law of large numbers: if you have enough elements it is only their average behavior that counts. The same idea underlies thermodynamics and statistical mechanics: if we have a *very* large number of individual atoms behaving chaotically, we will have no chance in predicting properties of individual atoms. However, new emergent properties such as temperature and pressure are predictable.

Humans are no atoms of course, and although in Asimov's universe there are many more humans to average over than the 6 billion that live today, the appearance of "The Mule" does cause a breakdown of the predictions. Interestingly, one can relate this idea to recent insights in physics and mathematics that societies are in a state of "self criticality". At its core this means that small disturbances can have large consequences that propagate through the entire system. To give an example from human history: the invention of the atomic bomb by a few scientists changed history radically.

Despite these potential objections, Jared Diamond's book "Guns, Germs and Steel" is the best psychohistory of the human race I have read so far. In fact, personally I find this book the best popular scientific read on my list, right next to the "Selfish Gene" by Richard Dawkins.

What are Diamonds claims? He claims that despite the sometimes large impact of individuals there are also very important and predictive regularities of human history that depend on geography. Why did the European colonist basically wipe out the native Indian population in America and not the reverse? The core reason, so he argues, lies in the fact that massive food production was first invented in the Fertile Crescent (the Iraque, Iran region). The climate was ideal for many species of plant and animal to become domesticated. Moreover, the East-West orientation of Eurasia made it easy for inventions to spread to Europe (and as far as China, although China seemed to have invented food production around the same time). Food production made it possible to switch from a hunter-gatherer life style to a farming lifestyle which in turn made it possible for many people to specialize in other things than farming. This way, larger cities and states started to emerge with a specialized fighting caste. These "successful" states then spread either by conquest or by simply producing more offspring.

But surprisingly, even more important than having powerful new weapons was the fact that cattle generates diseases and thus living among cattle causes a population to become resistant to lethal diseases such as small pox, measles and so on. (of course the price paid for this resistance was a high death toll because for a population to become resistant an aweful lot of cruel "selection of the fittest" will have to take place first.) In the America's, food production was much tougher due to climate issues and due to the North-South axis which prevented effective spreading of inventions. Also, very few large animals were available for domestication (perhaps they were all killed when the first people started settling a long time ago). So when the Spanish arrived they did not only have superior weapons and administration skills, they carried many more lethal diseases with them as well.

Diamond goes on to tell the amazing story of many continents: how the Polynesians were former Chinese evicted from the main land, how the aboriginals from Australia were decimated by Europeans, how the Buntu people spread over much of Africa by using superior farming practices. If you need to remember one thing it is this: it is massive food production that has caused all the major migrations and colonizations of populations. And perhaps equally important, the fact that one civilization ended up dominating another has nothing to do with race, it has to do with geography.

So it seems some form of psychohistory is still possible, even though we are averaging over tiny numbers compared to the numbers Asimov had in mind. I warmly recommend this book to anyone who is even vaguely interested in how the world has become what it is today.

1 comment:

  1. In his follow-on book, "Collapse: How Societies Choose to Fail or Succeed" Jared Diamond adds a few very interesting addtional variables to his societal evolution/devolution model. Anyone that has read "Guns, Germs and Steel" MUST read Collapse.