Is science as global as we think

A cornerstone of scientific practice is the perceived freedom with which knowledge is disseminated. But does the scientific community make good use of all that is available? Researchers have, on occasion, been accused of preferentially citing the work of colleagues close to home while ignoring those from other parts of the world [1, 2]. Such practices, if true, raises serious concerns about the free flow of scientific information [1]. Recently, Leimu and Koricheva [3] showed that ecological papers written by US authors attracted significantly more citations than did papers by European authors. They suggested that such differences could, potentially, be due to parochial citation practices; papers by US based authors could receive more citations if they are attracting, not only their fair share of European citations, but also a disproportionate share of citations from the US ([3], see also [1, 4]). In one journal (Oecologia), such a pattern was indeed found [5]. Here, we test if such a geographic citation bias extends to other journals and different types of papers, and if biases diminish over time as important results get more widely known. For analysis, we compared publications from two major geographic regions: Europ