  Galaxies in the Universe are distributed in a web-like structure
characterised by different large-scale environments: dense clusters, elongated
filaments, sheetlike walls, and under-dense regions, called voids. The low
density in voids is expected to affect the properties of their galaxies.
Indeed, previous studies have shown that galaxies in voids are on average bluer
and less massive, and have later morphologies and higher current star formation
rates than galaxies in denser large-scale environments. However, it has never
been observationally proved that the star formation histories (SFHs) in void
galaxies are substantially different from those in filaments, walls, and
clusters. Here we show that void galaxies have had, on average, slower SFHs
than galaxies in denser large-scale environments. We also find two main SFH
types present in all the environments: 'short-timescale' galaxies are not
affected by their large-scale environment at early times but only later in
their lives; 'long-timescale' galaxies have been continuously affected by their
environment and stellar mass. Both types have evolved slower in voids than in
filaments, walls, and clusters.
