Guns, Germs, and Steel (and Genetics)

In his Pulitzer prize-winning book, Gun, Germs, and Steel, Jared Diamond made the case that ancient societies succeeded based on the luck of the geographical draw.

At the end of the last Ice Age some 11,000 years ago, societies who found themselves in regions with good climate and soil as well as plenty of domesticable animals -- like most Eurasian civilizations -- were ideally placed to prosper. Societies like those in the Americas and Australia got the short end of the stick.

"History followed different courses for different peoples because of differences among peoples' environments, not because of biological differences among peoples themselves," Diamond wrote.

But is that really why we see such different economic outcomes around the world today?

Here's a thought experiment: Imagine two societies, one with very little genetic diversity and the other bursting at the double helix.

The diverse group is going to spawn different cultures with various solutions to the same problem.

Over the long run, you'd expect the best solution to win out. But in the short- to medium-term, the differences between people will be surely harder to overcome. History has plenty of examples of this, but see here and here for contemporary ones.

Now on the other hand, if everybody is genetically similar they're likely get along great, but the pool of ideas to choose from for solving problems will be a shallow one.

Following this line of logic, Quamrul Ashraf and Oded Galor of Brown University thought there might be a middle bowl of porridge that has just the right combination of difference and sameness that would allow a society to excel.

So how to go about proving this? Gene pools in today's societies are too jumbled up thanks to the mass migration of the past 500 years to be very helpful, so Ashraf and Galor stepped back in time to the year 1500.

One problem they immediately ran up against was that income levels around the world at that time were close to subsistence levels, so looking at how much people earned in different parts of the world wouldn't tell them much about the differences between societies.

As a way around this, the researchers instead looked at each region's respective population density, or the number of people in an area. What makes density a good proxy for economic development is that whatever productivity improvements a society made back then were channeled into agricultural improvements in order to support higher population levels. So if one region has a higher population density than another region of the same size, it implies that the first region is more economically developed than the second.

Looking at the genetic makeup of societies around the world in 1500, the researchers found that genetic variations explained about 25 percent of the different economic outcomes. (They performed the same tests for the years 1 and 1000 and came to similar conclusions.)

"We don't argue that there is one set of genes as opposed to another set of genes that's important. It's a perfectly politically correct argument because we're saying that it's just the diversity of genetic makeup that's important," Galor told me.

While blowing up Diamond's claim that genes don't have anything to do with economic development, Ashraf and Galor do find support for Diamond's assertion that geography plays an important role in explaining why certain societies succeeded. It turns out that geographic differences also explain about 25 percent of economic outcomes.

What will Diamond's reaction be to the paper? I'm waiting to hear back from him, but Galor is hopeful he'll take it well.

"If he's not very dogmatic, he should be very pleased," Galor said. "On the one hand we confirmed the importance of [geography]. On the other hand we sort of belittled his argument that genetics is not important. But he should be happy with the first argument because it's the important one. The other one was very speculative and perhaps wishful thinking in retrospect."