The increasing involvement of women in politics over past decades has highlighted distinct gender differences in positions on political issues (Eagly & Diekman, 2006; Vowles, 1993). More men than women tend to support issues such as longer prison sentences, while more women than men tend to support government spending on social welfare, health and education (Pratto, Stallworth & Sidanius, 1997). The gender gap in political issues often divides along the lines of conservative versus liberal, and right versus left, with men tending to be more conservative and right-wing, and women more liberal and left-leaning (Feather, 1977; McCue & Gopoian, 2000; Pratto et al., 1997; Rippl & Seipel, 1999; Sidanius & Liu, 1992). Women tend to be less supportive of military spending and involvement in war than men (Conover & Sapiro, 1993; Pratto et al., 1997; Sidanius & Liu, 1992), score lower on measures of prejudice and support for discriminatory policy (e.g., Altemeyer, 1998; Eagly, Diekman, Johannesen-Schmidt, & Koenig, 2004; Ekehammer, 1985), are less militaristic (e.g., Doty, Winter, Peterson, & Kemmelmeier, 1997; Heskin & Power, 1994; Pratto et al., 1997; Sapiro, 2001; Shapiro & Mahajan, 1986), hold less negative attitudes towards homosexuals (e.g., Eagly et al., 2004; Whitley & AEgisdottir, 2000), and generally hold less punitive attitudes (e.g., Ekehammer, 1985; Sears, Lau, Tyler, & Allen, 1980; Stack, 2000), to name but a few.
These sex differences appear to translate into voting behaviour, with women seven points less likely to support George W. Bush than John Kerry in the 2004 US election, and 10 points less likely in 2000 (Center for American Women and Politics, 2004). This pattern is also evidenced in New Zealand with the support for Labour as the traditional party of the left comprising more than 55% women since 1993. In contrast, National party support comprises between 45% and 50% women, while women represent as little as 30% of those voting for the Act party, the most far-right of the elected parties (e.g., Banducci & Karp, 2000; Levine & Roberts, 2000; Vowles, 1993; 2004). These trends continued in 2005 (Young, 2005). In addition, support for New Zealand's anti-nuclear policy was stronger among women than men (Bain, 2005).
Particularly promising as a potential explanatory factor in the range of socio-political sex differences is Social Dominance Orientation (SDO: Pratto, Sidanius, Stallworth, & Malle, 1994; Sidanius & Pratto, 1999), a relative newcomer to the pantheon of hot individual difference constructs in social psychology. According to Social Dominance Theory (SDT: Pratto et al., 1994; Sidanius, 1993; Sidanius & Pratto, 1999) post-industrial societies tend to develop group-oriented social hierarchies which assist in the maintenance of long-term human survival. In these hierarchies, intergroup conflict and oppression function to maintain the social system. Together with Right-Wing Authoritarianism (RWA, a syndrome of punitive and traditional social attitudes: Altemeyer, 1981; 1998) SDO is an important predictor of socio-political attitudes (Altemeyer, 1998; Sibley, Wilson & Duckitt, 2007).
Unlike RWA, however, there is consistent evidence of a sex difference in SDO (Pratto et al., 1994; Sidanius & Pratto, 1999). One of the characteristics of contemporary hierarchical systems is that they are overwhelmingly 'andrarchical'--males tend to hold the lions' share of political power (Sidanius & Pratto, 1999) allowing males to act to maintain their privileged social position. It follows, then, that males should favour social systems that perpetuate hierarchies as they tend to occupy privileged positions in them. In other words there should be a sex difference with males endorsing anti-egalitarian beliefs more than females. Indeed, this 'invariance hypothesis' is a foundational hypothesis of SDT though, at the same time, the authors of SDT would argue that is all it is--an hypothesis open to refutation. …