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Protesters carry Esteladas, Catalan separatist flags, and Basque flags, during a rally in favor of a referendum on independence from Spain for the autonomous community of Catalonia, in the Basque city of Bilbao.
The recent wave began in September with the independence referendum in Kurdistan, a semi-autonomous region in northern Iraq, in which Kurds voted overwhelmingly for statehood.
Iraq's government rejected the landmark vote, and tensions continue to rise between the Kurds and officials in Baghdad.
Then came the fiery independence vote in Catalonia on October 1, the validity of which Spain's central government has also rejected. More than 90% of Catalans voted "yes" for independence.
Catalonian president Carlos Puigdemont said the region won the right to be independent, but on Tuesday proposed suspending the secession process in order to have a dialogue with the Spanish government, since such a move would have significant economic and political consequences.
The Catalan vote reportedly inspired leaders of a secessionist movement in Brazil called, "The South Is My Country," to hold an informal vote on independence of their own.
On the same day as the Catalan vote, Cameroonian security forces killed 17 protestors during a demonstration held by advocates for a separation of Cameroon's southern English-speaking population from its northern French-speaking neighbors.
Similar independence movements are also bubbling up in Nigeria, Scotland, and Ontario, to name a few.
The seemingly contagious tide of independence movements around the world over the last month has many researchers and political analysts questioning whether calls for independence in one place can cause similar movements in other areas.
Is secessionism contagious?
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People carry Kurdistan flags during a May Day demonstration in Istanbul.
Scholars have repeatedly investigated the "contagion theory," secessionist expert Jason Sorens of Dartmouth University told Business Insider.
"There is some evidence that secessionism in one part of a country tends to spread to other parts of the same country," Sorens said. "And there is also evidence that when a central government fails to put down one armed self-determination conflict, another one is more likely to emerge in the same country.
"But there really doesn't seem to be any hard evidence behind the concern that allowing independence to occur in one place will encourage similar movements elsewhere around the world."
Steve Saideman, political scientist at Carleton University in Canada, has also found little evidence that secessionist movements are contagious across borders.
In a 2007 study, Saideman examined the argument that "internal processes are more important in the development of separatism and its spread within individual states" than "exposure to some external event," such as an independence referendum in another country.
REUTERS/Vincent West
Pro-Basque independence party Bildu supporters stick posters in favour of the Scottish independence referendum.
Today's wave of independence movements isn't the first time scholars have investigated the idea that secessionism might be contagious. In the 1990s, a similar trend of independence movements in Yugoslavia, the Soviet Union, and Czechoslovakia seemed to support the contagion theory.
But Sorens and Saideman refute the idea, saying there is simply no evidence that secessionism spreads from country to country.
Earlier this year, two researchers at the University of Maryland also investigated the contagion theory. While they argued that "self-determination is, to some extent, contagious," it is mainly only true internally among people within the same state or nation.
"We argue that seeing self-determination claims emerge nearby leads to a spread of identification with self-determination related identity and claims," the researchers concluded.
Unless experts settle on a theory, it may just be coincidence.