Researchers in Zurich have scientifically proven what most Swiss have known for decades but did not like to acknowledge: that there is a vast divide between French- and German-speaking Switzerland. They found, too, that the so-called "Röstigraben" is growing wider.
The most significant finding is that, over the past 10 years, the two language communities have become increasingly polarised, with francophone areas moving to the left and German ones to the right.
The shift has been so dramatic that it has now reached the point where the political complexion of the most conservative French-speaking cantons is almost the same as that of the most liberal German-speaking ones.
"Everyone talks about the Röstigraben, but you can't see it," said Michael Hermann, one of the two Zurich University researchers responsible for the study.
"We've tried to represent it graphically," said Hermann, who works in the university's social geography department.
By examining the results of every federal election over the past 20 years, Hermann and his colleague, Heiri Leuthold, were able to plot the political evolution of each region.
They found that the political differences which separate German- and French-speaking Switzerland are becoming increasingly stark.
The study, funded by the Swiss National Foundation for Scientific Research, found that people in French-speaking cantons tended to be more liberal on social issues, more pro-European and generally more supportive of government.
German-speakers, by contrast, were more suspicious of foreigners, more environmentally aware and more preoccupied with the concept of private property.
Hermann said the most significant changes in the 1980s were that German-speaking areas became more ecologically minded, while French-speaking governments became more technocratic.
By the 1990s, the two regions were growing apart politically, and this trend has continued to the present day.
Hermann and Leuthold show, for example, that even in the traditionally conservative parts of French-speaking Switzerland - canton Valais and rural parts of canton Vaud and Fribourg, for example - there was a definite shift to the left.
This has been accompanied by a dramatic swing to the right in German-speaking areas, even in cities like Basel and Zurich, which have a strong socialist tradition.
The cantons of Vaud, Fribourg and Valais may still be situated to the right of centre in the political spectrum, but now, Hermann told swissinfo, "they vote like the most left-wing German-speaking cities".
Stronger economic growth
He believes the leftward drift in French-speaking cantons is largely a result of stronger economic growth in German-speaking areas and the increasing importance of Zurich, not only as the country's economic capital, but also as the power base of the vociferously anti-immigrant and anti-European wing of the Swiss People's Party.
In the early 1990s, French-speaking Switzerland was much harder hit by recession and unemployment than the German areas.
"When there only cultural differences, there is no problem. But as soon as there is a component of dominance, then there are problems," Hermann said.
Equally there resentment in French speaking areas that, in federal votes, their voice is too often drowned out by their German-speaking compatriots. There have been several recent referenda in which French speakers have backed a proposal, only to see it blocked by German speakers.
"This leads to frustration and a feeling of being dominated," Hermann said. "That's a classic reason for left-wing sentiment to develop."
Whether this process will continue is difficult to predict, but there are signs that the causes of the divisions are lessening.
The economy is doing better throughout Switzerland, social divisions have narrowed, and last year Swiss voters approved closer ties with the EU - defusing, at least temporarily, the controversy over European integration.
However, Hermann believes the dominance of Zurich will continue, while the moderating influence of central cantons like Bern is likely to diminish.
"That bridge between the regions is disappearing. The centre of gravity of the German-speaking part is moving eastwards," Hermann said. "But I don't think this is the beginning of the end of the confederation."
by Roy Probert