“It might be a good idea,” the US journalist Bill Vaughan once suggested, “if the various countries of the world would occasionally swap history books, just to see what other people are doing with the same set of facts.”

History is famously written by the winners, and does tend to huddle inside national boundaries. Science is different, or so researchers like to believe. It is an international process. Facts are shared. Differences are ironed out. Scientists know what other people are doing. Correct?

Yes and no. As an impressive analysis of some 25 million research papers in a Comment on page 557 shows, international collaboration plays an increasing part in twenty-first-century research. The growth in scientific output from the United States and western Europe in the past three decades, for example, is entirely down to international collaboration. The number of journal articles that feature authors entirely from a single country in those regions has remained the same.

Only because of global links can the UK government claim, as it did in a 2011 report, that the country creates “14 per cent of the world’s highly cited output” with just “4 per cent of the world’s gross expenditure” on research and development. Most of those high-impact papers include the contribution of a foreign scientist. In fact, in 2010, the number of ‘British’ papers produced with help from abroad exceeded those made entirely in Britain for the first time.

According to the US National Science Foundation, almost one-quarter of global research articles in 2010 featured authors from more than one country, up from 10% in 1990. The average number of authors has doubled since 1980 and now stands at 4.5.

Although Nature welcomes the global reach of science, we have previously pointed out that internationalization will rub up against some natural boundaries. National pride and prestige matter, not least because science is still mostly funded and managed on a national basis.

Last October, in a special issue on the globalization of science, we said: “Mobility cannot stretch infinitely: relationships, families and quality of life put limits on how much researchers want to travel, and for how long” (Nature 490, 309–310; 2012). And we pointed out that collaboration could blur the borders of national priorities, especially for countries that are just beginning to develop their science bases.

The science bases of some of the bigger developing economies are coming along just fine, thank you. As the Comment points out, most of the scientific growth in China, Brazil and South Korea is driven by domestic work. And quality is rising. The citation impact of more than 10% of China’s domestic research is greater than twice the world average.

What does this mean? A change in international dynamics for starters, as Jonathan Adams points out in the Comment: “The older economies can no longer rely on the best foreign researchers to come and visit.”

There are opportunities galore in this new world, but Adams also highlights some of the threats. The best institutions in different countries already tend to work together the most. Others can find it hard to join this global competition. “There is a growing divide between international and domestic research,” Adams notes. “This will influence each nation’s ability to draw on the global knowledge base, and could in turn compromise national scientific wealth.” It is not just between nations that science must be shared, but within their borders too.