minate others. This is indeed the case. It has been shown that males with broad chins are perceived in 8 cultures as those who are likely to dominate others. Allan Mazurand colleagues have put comparable results forward. These authors describe careers of West Point cadettes - those with broad chins at entrance to West Point rose higher in the military hierarchy than others do. On the other hand a broad chin could signal an immunohandicap. This is the case because testosterone production might be costly, due to suppression of the immune function and thereby increasing disease susceptibility during puberty. Immunocompetence is highly relevant because the steroid reproductive hormones may negatively impact immune function. When competition for mates is intense, some extreme traits might help to rivet a roving eye. A male peacock is saying ' look at me, I have this big tail. I couldn't grow a tail this big if I had parasites'. Even if the trait is detrimental to survival, the benefit in additional offspring brought by attracting females can more than compensate for the decrease in longevity. The concept seems applicable to humans, because it helps resolve a nagging flaw in average-face studies. Extreme male features advertise honestly that their bearer was sufficiently parasite resistant to produce them. But male facial features cannot become extreme, as expected. Perret and colleagues showed that adding a feminine touch to a male face makes it more attractive. The reason seems to be clear, broad jaws signal high testosterone levels and thus also possible aggressiveness. If females rely on stable relationships male aggressiveness may also turn against them. Thus there is an upper limit for male jaw width - this is when the feature might also become disadvantageous to females. In addition female chins and lower faces are small when they are attractive - this might signal the absence of male sex hormon...
