The Bruckner University The line of fifths and the co-evolution of tonal pitch-classes In this study, we determine the fundamental role of the line of fifths for the organization of tonal material by applying dimensionality reduction to a large historical corpus of pitch-class counts (ca. 1360–1940). We observe a historically growing trend in the exploitation of the fifths range, i.e. the size of segments that pitch-class distributions cover on the line of fifths. Moreover, we introduce the novel concept of pitch-class (co-)evolution, which traces the changing co-occurrence of pitch classes over time and likewise reaffirms the centrality of this linear tonal space from a historical angle, allowing us also to distinguish between historical periods in terms of the usage of pitch classes. en TEXT journal article Wissenschaftlicher Artikel Articolo di rivista Text journal article Text Wissenschaftlicher Artikel Testo Articolo di rivista line of fifths tonal-pitch classes dimensionality reduction pitch-class co-evolution 2022 2022 Fabian C. Moss Markus Neuwirth Martin Rohrmeier