The history of the dark matter problem can be traced back to at least the
1930s, but it was not until the early 1970s that the issue of 'missing matter'
was widely recognized as problematic. In the latter period, previously separate
issues involving missing mass were brought together in a single anomaly. We
argue that reference to a straightforward 'accumulation of evidence' alone is
inadequate to comprehend this episode. Rather, the rise of cosmological
research, the accompanying renewed interest in the theory of relativity and
changes in the manpower division of astronomy in the 1960s are key to
understanding how dark matter came to matter. At the same time, this story may
also enlighten us on the methodological dimensions of past practices of physics
and cosmology.Comment: Accepted for publication in Nature Astronomy. Corrected typ
