  We present the reconstructed evolution of rest-frame ultra-violet (UV)
luminosities of the most massive Milky Way dwarf spheroidal satellite galaxy,
Fornax, and its five globular clusters (GCs) across redshift, based on analysis
of the stellar fossil record and stellar population synthesis modeling. We find
that (1) Fornax's (proto-)GCs can generate $10-100$ times more UV flux than the
field population, despite comprising $<\sim 5\%$ of the stellar mass at the
relevant redshifts; (2) due to their respective surface brightnesses, it is
more likely that faint, compact sources in the Hubble Frontier Fields (HFFs)
are GCs hosted by faint galaxies, than faint galaxies themselves. This may
significantly complicate the construction of a galaxy UV luminosity function at
$z>3$. (3) GC formation can introduce order-of-magnitude errors in abundance
matching. We also find that some compact HFF objects are consistent with the
reconstructed properties of Fornax's GCs at the same redshifts (e.g., surface
brightness, star formation rate), suggesting we may already have detected
proto-GCs in the early Universe. Finally, we discuss the prospects for
improving the connections between local GCs and proto-GCs detected in the early
Universe.
