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:…2003), they can be regarded as a natural experiment in carnivore social evolution whose outcome can potentially reveal evolutionary transitions between different levels of carnivore sociality as well as insights into the mechanisms driving social evolution in general (Schneider and Kappeler 2014).
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