Science moves toward safer mixing of related fields over time
The conservative turn in science: The changing character of knowledge recombination
Social and Information NetworksDigital Libraries
Summary
Combining knowledge from different scientific fields helps create new discoveries, but this study finds that over the last six decades, scientists are increasingly combining fields that share some common ground rather than very different ones. The researchers analyzed millions of papers and citations and showed that cross-disciplinary work now tends to link fields that overlap partially instead of being completely separate. This change also means that science draws more on older research and spreads collaborative roles more widely. The authors suggest these patterns affect decisions about funding and supporting interdisciplinary research.
cross-disciplinary citationsknowledge recombinationsemantic distanceSPECTER-v2 embeddingsscience policyinterdisciplinary researchcitation analysisbrokerage positions
Authors
Cheng Zhang, Xinkun Liang, Yi Bu, Hongkan Chen
Abstract
This study examines how the dominant mode of cross-disciplinary knowledge combination has changed over time. It addresses a limitation of existing studies that document declining disruptiveness at the level of individual works but do not reveal whether the mechanisms of cross-disciplinary knowledge flow have themselves shifted. Drawing on 56 million publications and 816 million citations from OpenAlex (1960-2025), the study classifies cross-disciplinary citations into five types based on the set relationship between the subfield portfolios of citing and cited publications and introduces a semantic-distance measure derived from SPECTER-v2 embeddings of publication abstracts. It subsequently demonstrates that cross-disciplinary citations have shifted markedly away from configurations with no shared disciplinary ground toward types built on partially overlapping knowledge bases, a reorientation further reflected in a steady decline in average semantic distance between citing and cited fields. This shift co-occurs with a diffusion of brokerage positions across the network and a greater reliance on older literature, consistent with a system that has become broader and more decentralized in its interdisciplinary reach. Finally, this study discusses the implications of these findings for science policy and for the design of cross-disciplinary funding mechanisms.