Vol.:(0123456789) Scientometrics https://doi.org/10.1007/s11192-019-03248-z 1 3 Generating process of emerging topics in the life sciences Ryosuke L. Ohniwa 1,2  · Aiko Hibino 3 Received: 14 March 2019 © Akadémiai Kiadó, Budapest, Hungary 2019 Abstract Clarifying the mechanism of how emerging topics in science and technology research felds are generated is useful for both researchers and agencies to identify potential emerging top- ics of the future. In the present study, we use bibliometric analyses targeting data of about 30 million published articles from 1970 to 2017 on PubMed, the largest article database in the life science feld, to test our hypothesis that existing emerging topics contribute to the generation of new emerging topics in that feld. We frst collected emerging keywords from medical subject headings attached to each article using our previously reported methodol- ogy (Ohniwa et al. in Scientometrics 85(1):111–127, 2010, https://doi.org/10.1007/s1119 2-010-0252-2), and performed co-word analyses of each emerging keyword 1-year prior to it becoming an emerging keyword. About 75% of total emerging keywords, at 1-year prior to becoming identifed as emerging, co-appeared with other emerging keywords in the same article. Furthermore, most of the keywords co-appeared again at the point when the target keyword was identifed as emerging, which is consistent with our hypothesis regard- ing the mechanism that emerging topics generate emerging topics. Keywords Trends in life science · Emerging topics · MeSH terms · PubMed · Metrical index Introduction The detection of emerging topics in research activities, including emerging technologies, methodologies, and scientifc concepts, is considered to be helpful for implementing poli- cies and distributing research funding more efciently (Glanzel and Thijs 2012; Small et al. 2014). Currently, various scientometric approaches have been proposed to identify such emerging topics. Rotolo and colleagues (Rotolo et al. 2015) grouped these scientometric Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1119 2-019-03248-z) contains supplementary material, which is available to authorized users. * Ryosuke L. Ohniwa ohniwa@md.tsukuba.ac.jp 1 Faculty of Medicine, University of Tsukuba, Tennoh-dai, Tsukuba 305-8575, Japan 2 Center for Biotechnology, National Taiwan University, Taipei 106, Taiwan 3 Faculty of Humanities and Social Sciences, Hirosaki University, Hirosaki 036-8560, Japan