As part of the Dwarf galaxies Abundances and Radial-velocities Team ( DART ) Programme , we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies ( dSph ) : Sculptor , Sextans , Fornax and Carina .
The low mean metal abundances and the presence of very old stellar populations in these galaxies have supported the view that they are fossils from the early Universe .
However , contrary to naive expectations , we find a significant lack of stars with metallicities below { [ Fe / H ] } \sim - 3 dex in all four systems .
This suggests that the gas that made up the stars in these systems had been uniformly enriched prior to their formation .
Furthermore , the metal-poor tail of the dSph metallicity distribution is significantly different from that of the Galactic halo .
These findings show that the progenitors of nearby dSph appear to have been fundamentally different from the building blocks of the Milky Way , even at the earliest epochs .