  Nearly all of the well studied ancient globular clusters (GCs), in the Milky
Way and in nearby galaxies, show star-to-star variations in specific elements
(e.g., He, C, N, O, Na, Al), known as "multiple populations" (MPs). However,
MPs are not restricted to ancient clusters, with massive clusters down to
$\sim2$ Gyr showing signs of chemical variations. This suggests that young and
old clusters share the same formation mechanism but most of the work to date on
younger clusters has focused on N-variations. Initial studies even suggested
that younger clusters may not host spreads in other elements beyond N (e.g.,
Na), calling into question whether these abundance variations share the same
origin as in the older GCs. In this work, we combine HST photometry with
VLT/MUSE spectroscopy of a large sample of RGB stars (338) in the Large
Magellanic Cloud cluster NGC 1978, the youngest globular to date with reported
MPs in the form of N-spreads. By combining the spectra of individual RGB stars
into N-normal and N-enhanced samples, based on the "chromosome map" derived
from HST, we search for mean abundance variations. Based on the NaD line, we
find a Na-difference of $\Delta$[Na/Fe]$=0.07\pm0.01$ between the populations.
While this difference is smaller than typically found in ancient GCs (which may
suggest a correlation with age), this result further confirms that the MP
phenomenon is the same, regardless of cluster age and host galaxy. As such,
these young clusters offer some of the strictest tests for theories on the
origin of MPs.
