Chemical evolution for Fe, Si, Zn, Ni, P, Mg, Al, S, C, N, and O since the first stars started to die (z = 20) until z = 0. Model A starts with zero-metallicity stars, and as the Universe gets enriched, subsequent Pop II stars with increasing metallicity start to appear, until reaching Z = 2 × 10⁻² Z_⊙, according to the model described in Sect. 2.4. It is possible to observe the chemical avalanche in the early Universe given by the high production of metals from Pop III stars. As discussed in the text, model B considers only Pop II stars. The gray crosses represent data from Pettini et al. (1997, 2000, 2008), Centurion et al. (1998), Vladilo (1998), Dessauges-Zavadsky et al. (2002, 2003), Nissen et al. (2004), Akerman et al. (2005), Kulkarni et al. (2007), Prochaska et al. (2007), Penprase et al. (2010), Cooke et al. (2011), Kulkarni et al. (2012), Rafelski et al. (2012), Jorgenson et al. (2013), Neeleman et al. (2013), Zafar et al. (2014), and De Cia et al. (2016). All abundances were rescaled to solar values from Asplund et al. (2009).