With the award of the Nobel for economics to Thomas Sargent and Christopher Sims this week, the US once again took the lion’s share of the annual prizes. Its citizens gained seven awards (including the not-strictly-Nobel economics prize) and its grip on the Nobels shows little sign of weakening.

In the long run, it is bound to. Germany had an equally dominant share of Nobels before the Second World War but postwar emigration of many of its best scientists and the rise of federally-funded US research universities in the late 20th century put an end to it. The billions that Asian countries led by China are pouring into pure research will eventually even the score.

But the US is not trying hard enough to slow that trend, and so preserve one of its best claims to American exceptionalism. It needs to do more not only to draw masters and PhD students to its universities but to keep them after they graduate. Otherwise, US taxpayers will be investing heavily in the erosion of one of their country’s prime economic advantages.