COLUMBUS, Ohio — It’s good to have allies. Nations are less likely to go to war with “friends of friends,” a new study from Ohio State University finds.
The results, published Wednesday in the journal Science Advances, show that countries with indirect relationships are better equipped to prevent major armed conflicts with each other, suggesting that international military could matter more than we previously thought.
Researchers also noted something they found surprising: countries with three degrees of separation are more likely to be friendly. Nations have less of a chance of going to war with either their allies, allies of allies, and the allies of their allies’ allies, according to a university news release.
“The peacemaking impact of an alliance between two countries goes beyond the two that signed the agreement,” says Skyler Cranmer, lead author of the study and associate professor of political science at The Ohio State University, in the release. “It permeates the network of alliances, like ripples in a pond, to prevent conflicts beyond the two countries that have the alliance.”
The study looked at all major military conflicts throughout the world from 1965 to 2000 and found that the probability of a new war arising between two neighboring countries in a given year was between three to four percent for nations with three degrees of separation, but double that for nations with four degrees of separation.
“At four degrees, the countries no longer share membership in common communities that represent shared interests,” explains Cranmer.
According to the researchers, this adds to the body of evidence that human interactions seem to be influenced by three degrees of separation.
“There’s emerging evidence that this three-degree horizon of influence seems to be relatively common in human networks and can be found in political attitudes, health behaviors and the likelihood of smoking,” says Cranmer. “But this is the first evidence of anything like this in a political network.”