The evolution of sociality represen

The evolution of sociality represents one of the most enduring
and important questions in behavioural biology (Székely et al.
2010). Why do some species show complex social behaviour,
while other closely related species living in similar ecologies spend
the majority of their lives in solitude? To answer this question, it is
crucial that we develop an integrative perspective on social
behaviour that includes a thorough understanding of the proximate
mechanisms that generate social behaviour (Insel & Fernald 2004;
Young 2009; Soares et al. 2010). The nonapeptide oxytocin (and its
nonmammalian homologues; e.g. isotocin in teleost fish, mesotocin
in birds and reptiles) represents a promising candidate system for
the modulation of social behaviour (for recent reviews see:
Donaldson & Young 2008; Goodson 2008; Lee et al. 2009; Ross &
Young 2009; Goodson & Thompson 2010; Insel 2010).
Oxytocin acts both as a central neuromodulator and a pe