Quick tidbit from this study: by covertly manipulating the posture of male and female subjects and then testing their mood and performance before and after postural modification, researchers were able to determine that:

• men feel and perform better when adopting an upright "power" posture
• women feel and perform better when adopting a slumped "submissive" posture

The reverse was also true: men made to slump felt and performed worse, women made to stand upright felt and performed worse.

The jury's still out on a causal explanation, but one of the theories put forth by the authors is that males are evolutionarily conditioned to seek social dominance and display it through a dominant posture (hence feeling positive, rewarded and effective when adopting one), while females are evolutionarily conditioned to be submissive and display through a submissive posture (hence feeling positive, rewarded and effective when adopting it).

Tip G_Petronius for their post.