Zinc abundances as a function of stellar ages/look-back time (lower x-axis), and redshift (upper). Red triangles are DLAs (compilation from Quiret et al. 2016), blue circles are Sculptor stars (Skúladóttir et al. 2017; ages from de Boer et al. 2012), and yellow pentagons are Carina stars (Shetrone et al. 2003; Venn et al. 2012; ages from Lemasle et al. 2012). Colored regions show the area occupied by available measurements: Draco in pink (Shetrone et al. 2001; Cohen & Huang 2009); and Sagittarius in dark green (Sbordone et al. 2007). The Milky Way is shown in gray: diamonds are the bulge (Bensby et al. 2013), squares are the disk (Reddy et al. 2006) and the halo is shown with a shaded area (Cayrel et al. 2004; Reddy et al. 2006; Nissen et al. 2007).