 More work is needed in how to relate different kinds of hierarchies to questions of reductionism. Biological hierarchies are diverse (Grene 1987, Korn 2002, 2005), and some areas of biological research, such as paleontology and systematics (Valentine and May 1996, see also Grantham 1999, 2004a, 2004b, 2007), have been ignored when reductionism comes into view. Paying attention to temporality encourages the exploration of functional or control hierarchies in more detail (Salthe 1985, 1993, Wimsatt 2002). The limitations of representing biological systems in terms of hierarchies should be explored in more depth as well (Brooks 2014, O’Malley et al. 2014, Potochnik and McGill 2012).