From a new NBER working paper: We examine the empirical relationship between the occurrence of interstate conflicts and the degree of relatedness between countries, showing that populations that are genetically closer are more prone to go to war with each other, even after controlling for a wide set of measures of geographic distance and other factors that affect conflict, including measures of trade and democracy.
Genetic distance is a better indicator of contact between nations than geographic distance. As Jay noted, terrain matters. Greece is very close to Libya. Saudi Arabia is very close to Sudan. Italy is very close to Germany. But soldiers and lovers both need roads.
They control for geographic proximity, but is that enough? The intervening terrain matters enormously. Marching across a flat plain is much easier than establishing a beachhead in a naval invasion.
Perhaps it's because people who share genetic links tend to share cultural, linguistic and historical connections that make it more likely for inter-state conflicts to even be possible. People (population and state-members) tend to have far more social and pecuniary interest in societies they know of and have some physical or commercial mobility in. States fight wars more for reputation and sovereignty than for control of land, especially in a highly capital mobile world. Englishmen are much more likely to have economic interests in South Africa or America than China.
I'd say that most of the things they 'control' for are really impossible. Countries that have a great deal to do with each other will have genetic similarities, because of cross-contamination. Why would countries have recent cross contamination other than trade or physical proximity? Control for those reasons as well and... well, you'll run out of opportunities for war...
Coding aside: Notice that when this comment is listed in the Recent Comments list, the link to the comment doesn't work as intended, presumably because of interference with the link in the comment (to the "ungated version").
I agree, parent should have RTFA, but the writers hypothesize that:
more closely related populations, on average, tend to interact more and develop more disputes over sets of common issues
The causal links thus seem to be:
People who interact more tend to come into conflict more.
People who are more closely related tend to interact more.
I'm not sure these aren't trivial. I suppose that what's really non-trivial is that these factors outweigh possible countervailing factors, for example:
People who interact less have less to lose from a loss of interaction, and war reduces (peaceful) interaction.
That this factor is swamped by other factors seems to argue against the commonly held view that establishing economic ties between countries is a good way to encourage peace. The study suggests that economic ties may actually encourage war.
You just assumed that the most obvious potential flaw in such a study was completely overlooked by the authors, despite the reference to those very controls consuming nearly half of the quoted passage. Please don't make a slashdot of this place.
How much longer before the US reverses the trend?
This is trivial.
Peoples who are neighbors (as in neighboring countries, fiefdoms, lands) fight each other. Unless you have an air force or navy, it's difficult to fight with a non-neighbor. HIstorically only a small fraction of wars involve non-neighbors.
But peoples who are neighbors also intermarry and so are more genetically similar.
Again, this is a triviality.
Here is an ungated version if anyone is interested.
That's similar to the meme that most animal conflict is intra-species; your closest competitors are those most like you.
Score one for Freud. Sounds a lot like the "narcissism of minor differences."
Won't Frank Salter be shocked.