Facial sexual dimorphism increases at puberty. In pubertal males, a high testosterone-to-oestrogen ratio stimulates the growth of the jaw, cheekbones, brow ridges, centre of the face (from brow to bottom of the nose), and facial hair. For pubertal females, a high oestrogento-testosterone ratio prevents this growth but contributes to increase in lip size (Thornhill & Møller, 1997). Testosterone may stress the immune system so that only healthy males may better afford predominant male features. Therefore, testosterone-dependent secondary sexual characteristics in males (i.e., masculine faces) may signal immunological strength and are sexually selected for in several species (Folstad & Karter, 1992;Peters, 2000). For humans, oestrogen-dependent characteristics of female faces have been associated with health and reproductive fitness and are often perceived as more attractive (Scott et al., 2008). Studies investigating facial dimorphism have found that facial expressions of