Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:, 2008; Cahill, 2006; Camarata and Woodcock, 2006) and animals (Clark et al., 2000a,b; Fitch et al., 1993b; Herman et al., 1997).
Category: